WorldWideScience

Sample records for electroactive controlled release

  1. Coated electroactive materials

    Science.gov (United States)

    Amine, Khalil; Abouimrane, Ali

    2016-08-30

    A process includes suspending an electroactive material in a solvent, suspending or dissolving a carbon precursor in the solvent; and depositing the carbon precursor on the electroactive material to form a carbon-coated electroactive material. Compositions include a graphene-coated electroactive material prepared from a solution phase mixture or suspension of an electroactive material and graphene, graphene oxide, or a mixture thereof.

  2. Electroactivity in Polymeric Materials

    CERN Document Server

    2012-01-01

    Electroactivity in Polymeric Materials provides an in-depth view of the theory of electroactivity and explores exactly how and why various electroactive phenomena occur. The book explains the theory behind electroactive bending (including ion-polymer-metal-composites –IPMCs), dielectric elastomers, electroactive contraction, and electroactive contraction-expansion cycles.  The book also balances theory with applications – how electroactivity can be used – drawing inspiration from the manmade mechanical world and the natural world around us.  This book captures: A complete introduction to electroactive materials including examples and recent developments The theory and applications of numerous topics like electroactive bending of dielectric elastomers and electroactive contraction and expansion New topics, such as biomimetic applications and energy harvesting This is a must-read within the electroactive community, particularly for professionals and graduate students who are interested in the ...

  3. Electro-active sensor, method for constructing the same; apparatus and circuitry for detection of electro-active species

    Science.gov (United States)

    Buehler, Martin (Inventor)

    2009-01-01

    An electro-active sensor includes a nonconductive platform with a first electrode set attached with a first side of a nonconductive platform. The first electrode set serves as an electrochemical cell that may be utilized to detect electro-active species in solution. A plurality of electrode sets and a variety of additional electrochemical cells and sensors may be attached with the nonconductive platform. The present invention also includes a method for constructing the aforementioned electro-active sensor. Additionally, an apparatus for detection and observation is disclosed, where the apparatus includes a sealable chamber for insertion of a portion of an electro-active sensor. The apparatus allows for monitoring and detection activities. Allowing for control of attached cells and sensors, a dual-mode circuitry is also disclosed. The dual-mode circuitry includes a switch, allowing the circuitry to be switched from a potentiostat to a galvanostat mode.

  4. Wirelessly Controllable Inflated Electroactive Polymer (EAP) Reflectors

    Science.gov (United States)

    Bao, Xiaoqi; Bar-Cohen, Yoseph; Chang, Zensheu; Sherrit, Stewart; Badescu, Mircea

    2005-01-01

    Inflatable membrane reflectors are attractive for deployable, large aperture, lightweight optical and microwave systems in micro-gravity space environment. However, any fabrication flaw or temperature variation may results in significant aberration of the surface. Even for a perfectly fabricated inflatable membrane mirror with uniform thickness, theory shows it will form a Hencky curve surface but a desired parabolic or spherical surface. Precision control of the surfaceshape of extremely flexible membrane structures is a critical challenge for the success of this technology. Wirelessly controllable inflated reflectors made of electroactive polymers (EAP) are proposed in this paper. A finite element model was configured to predict the behavior of the inflatable EAP membranes under pre-strains, pressures and distributed electric charges on the surface. To explore the controllability of the inflatable EAP reflectors, an iteration algorism was developed to find the required electric actuation for correcting the aberration of the Hencky curve to the desired parabolic curve. The correction capability of the reflectors with available EAP materials was explored numerically and is presented in this paper.

  5. Electroactive oligoaniline-containing self-assembled monolayers for tissue engineering applications.

    Science.gov (United States)

    Guo, Yi; Li, Mengyan; Mylonakis, Andreas; Han, Jingjia; MacDiarmid, Alan G; Chen, Xuesi; Lelkes, Peter I; Wei, Yen

    2007-10-01

    A novel electroactive silsesquioxane precursor, N-(4-aminophenyl)-N'-(4'-(3-triethoxysilyl-propyl-ureido) phenyl-1,4-quinonenediimine) (ATQD), was successfully synthesized from the emeraldine form of amino-capped aniline trimers via a one-step coupling reaction and subsequent purification by column chromatography. The physicochemical properties of ATQD were characterized using mass spectrometry as well as by nuclear magnetic resonance and UV-vis spectroscopy. Analysis by cyclic voltammetry confirmed that the intrinsic electroactivity of ATQD was maintained upon protonic acid doping, exhibiting two distinct reversible oxidative states, similar to polyaniline. The aromatic amine terminals of self-assembled monolayers (SAMs) of ATQD on glass substrates were covalently modified with an adhesive oligopeptide, cyclic Arg-Gly-Asp (RGD) (ATQD-RGD). The mean height of the monolayer coating on the surfaces was approximately 3 nm, as measured by atomic force microscopy. The biocompatibility of the novel electroactive substrates was evaluated using PC12 pheochromocytoma cells, an established cell line of neural origin. The bioactive, derivatized electroactive scaffold material, ATQD-RGD, supported PC12 cell adhesion and proliferation, similar to control tissue-culture-treated polystyrene surfaces. Importantly, electroactive surfaces stimulated spontaneous neuritogenesis in PC12 cells, in the absence of neurotrophic growth factors, such as nerve growth factor (NGF). As expected, NGF significantly enhanced neurite extension on both control and electroactive surfaces. Taken together, our results suggest that the newly electroactive SAMs grafted with bioactive peptides, such as RGD, could be promising biomaterials for tissue engineering.

  6. Multilayer Electroactive Polymer Composite Material

    Science.gov (United States)

    Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Park, Cheol (Inventor); Draughon, Gregory K. (Inventor); Ounaies, Zoubeida (Inventor)

    2011-01-01

    An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

  7. Modelling and Control of Ionic Electroactive Polymer Actuators under Varying Humidity Conditions

    Directory of Open Access Journals (Sweden)

    S. Sunjai Nakshatharan

    2018-02-01

    Full Text Available In this work, we address the problem of position control of ionic electroactive polymer soft actuators under varying relative humidity conditions. The impact of humidity on the actuation performance of ionic actuators is studied through frequency response and impedance spectroscopy analysis. Considering the uncertain performance of the actuator under varying humidity conditions, an adaptable model using the neural network method is developed. The model uses relative humidity magnitude as one of the model parameters, making it robust to different environmental conditions. Utilizing the model, a closed-loop controller based on the model predictive controller is developed for position control of the actuator. The developed model and controller are experimentally verified and found to be capable of predicting and controlling the actuators with excellent tracking accuracy under relative humidity conditions varying in the range of 10–90%.

  8. Electroactive polymers for healthcare and biomedical applications

    Science.gov (United States)

    Bauer, Siegfried

    2017-04-01

    Electroactivity was noticed early in biological substances, including proteins, polynucleotides and enzymes, even piezoand pyroelectricity were found in wool, hair, wood, bone and tendon. Recently, ferroelectricity has been identified in a surprisingly large number of biologically relevant materials, including hydroxyapatite, aortic walls and elastin. Inspired by the variety of natural electroactive materials, a wealth of new elastomers and polymers were designed recently, including an all organic elastomer electret and self-healing dielectric elastomers. Let's further draw inspiration from nature and widen the utilization of electroactive polymers towards (mobile) healthcare and biomedical applications. Ferroelectrets, internally charged polymer foams with a strong piezoelectric thickness coefficient are employed in biomedical sensing, for example as blood pressure and pulse sensor, as vital signs monitor or for the detection of tonicclonic seizures. Piezo- and pyroelectric polymers are booming in printed electronics research. They provide electronic skin the ability to "feel" pressure and temperature changes, or to generate electrical energy from vibrations and motions, even from contractile and relaxation motions of the heart and lung. Dielectric elastomers are pioneered by StretchSense as wearable motion capture sensors, monitoring pressure, stretch, bend and shear, quantifying comfort in sports and healthcare. On the cellular level, electroactive polymer arrays are used to study mechanotransduction of individual cells. Ionic electroactive polymers show potential to be used in implantable electroactive biomedical devices. Already with the currently available science and technology, we are at the verge of witnessing the demonstration of truly complex bionic systems.

  9. A review of integrating electroactive polymers as responsive systems for specialized drug delivery applications.

    Science.gov (United States)

    Pillay, Viness; Tsai, Tong-Sheng; Choonara, Yahya E; du Toit, Lisa C; Kumar, Pradeep; Modi, Girish; Naidoo, Dinesh; Tomar, Lomas K; Tyagi, Charu; Ndesendo, Valence M K

    2014-06-01

    Electroactive polymers (EAPs) are promising candidate materials for the design of drug delivery technologies, especially in conditions where an "on-off" drug release mechanism is required. To achieve this, EAPs such as polyaniline, polypyrrole, polythiophene, ethylene vinyl acetate, and polyethylene may be blended into responsive hydrogels in conjunction with the desired drug to obtain a patient-controlled drug release system. The "on-off" drug release mechanism can be achieved through the environmental-responsive nature of the interpenetrating hydrogel-EAP complex via (i) charged ions initiated diffusion of drug molecules; (ii) conformational changes that occur during redox switching of EAPs; or (iii) electroerosion. These release mechanisms are not exhaustive and new release mechanisms are still under investigation. Therefore, this review seeks to provide a concise incursion and critical overview of EAPs and responsive hydrogels as a strategy for advanced drug delivery, for example, controlled release of neurotransmitters, sulfosalicyclic acid from cross-linked hydrogel, and vaccine delivery. The review further discusses techniques such as linear sweep voltammetry, cyclic voltammetry, impedance spectroscopy, and chronoamperometry for the determination of the redox capability of EAPs. The future implications of the hydrogel-EAP composites include, but not limited to, application toward biosensors, DNA hybridizations, microsurgical tools, and miniature bioreactors and may be utilized to their full potential in the form of injectable devices as nanorobots or nanobiosensors. Copyright © 2013 Wiley Periodicals, Inc.

  10. Ductile electroactive biodegradable hyperbranched polylactide copolymers enhancing myoblast differentiation.

    Science.gov (United States)

    Xie, Meihua; Wang, Ling; Guo, Baolin; Wang, Zhong; Chen, Y Eugene; Ma, Peter X

    2015-12-01

    Myotube formation is crucial to restoring muscular functions, and biomaterials that enhance the myoblast differentiation into myotubes are highly desirable for muscular repair. Here, we report the synthesis of electroactive, ductile, and degradable copolymers and their application in enhancing the differentiation of myoblasts to myotubes. A hyperbranched ductile polylactide (HPLA) was synthesized and then copolymerized with aniline tetramer (AT) to produce a series of electroactive, ductile and degradable copolymers (HPLAAT). The HPLA and HPLAAT showed excellent ductility with strain to failure from 158.9% to 42.7% and modulus from 265.2 to 758.2 MPa. The high electroactivity of the HPLAAT was confirmed by UV spectrometer and cyclic voltammogram measurements. These HPLAAT polymers also showed improved thermal stability and controlled biodegradation rate compared to HPLA. Importantly, when applying these polymers for myotube formation, the HPLAAT significantly improved the proliferation of C2C12 myoblasts in vitro compared to HPLA. Furthermore, these polymers greatly promoted myogenic differentiation of C2C12 cells as measured by quantitative analysis of myotube number, length, diameter, maturation index, and gene expression of MyoD and TNNT. Together, our study shows that these electroactive, ductile and degradable HPLAAT copolymers represent significantly improved biomaterials for muscle tissue engineering compared to HPLA. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. 96X Screen-Printed Gold Electrode Platform to Evaluate Electroactive Polymers as Marine Antifouling Coatings.

    Science.gov (United States)

    Brisset, Hugues; Briand, Jean-François; Barry-Martinet, Raphaëlle; Duong, The Hy; Frère, Pierre; Gohier, Frédéric; Leriche, Philippe; Bressy, Christine

    2018-04-17

    Several alternatives are currently investigated to prevent and control the natural process of colonization of any seawater submerged surfaces by marine organisms. Since few years we develop an approach based on addressable electroactive coatings containing conducting polymers or polymers with lateral redox groups. In this article we describe the use of a screen-printed plate formed by 96 three-electrode electrochemical cells to assess the potential of these electroactive coatings to prevent the adhesion of marine bacteria. This novel platform is intended to control and record the redox properties of the electroactive coating in each well during the bioassay (15 h) and to allow screening its antiadhesion activity with enough replicates to support significant conclusions. Validation of this platform was carried out with poly(ethylenedioxythiophene) (PEDOT) as electroactive coating obtained by electropolymerization of EDOT monomer in artificial seawater electrolyte on the working electrode of each electrochemical cell of the 96-well microplate.

  12. Innovative approach for the electrochemical detection of non-electroactive organophosphorus pesticides using oxime as electroactive probe

    International Nuclear Information System (INIS)

    Dong, Jing; Hou, Juying; Jiang, Jianxia; Ai, Shiyun

    2015-01-01

    Highlights: • Novel approach for electrochemical detection of non-electroactive OPs was proposed. • PAM was used as electroactive probe for the first time. • The detection system displayed high sensitivity and promptness. • The developed sensor was used in real samples with satisfactory results. - Abstract: An innovative approach for sensitive and simple electrochemical detection of non-electroactive organophosphorus pesticides (OPs) was described in this report. The novel strategy emphasized the fabrication of an oxime-based sensor via attaching pralidoxime (PAM) on graphene quantum dots (GQDs) modified glassy carbon electrode. The introduction of GQDs significantly increased the effective electrode area, and then enlarged the immobilization quantity of PAM. Thus, the oxidation current of PAM was obviously increased. Relying on the nucleophilic substitution reaction between oxime and OPs, fenthion was detected using PAM as the electroactive probe. Under optimum conditions, the difference of oxidation current of PAM was proportional to fenthion concentration over the range from 1.0 × 10 −11 M to 5.0 × 10 −7 M with a detection limit of 6.8 × 10 −12 M (S/N = 3). Moreover, the favorable detection performance in water and soil samples heralded the promising applications in on-site OPs detection

  13. Multifunctional Electroactive Nanocomposites Based on Piezoelectric Boron Nitride Nanotubes

    Science.gov (United States)

    Kang, Jin Ho; Sauti, Godfrey; Park, Cheol; Yamakov, Vesselin I.; Wise, Kristopher E.; Lowther, Sharon E.; Fay, Catharine C.; Thibeault, Sheila A.; Bryant, Robert G.

    2015-01-01

    Space exploration missions require sensors and devices capable of stable operation in harsh environments such as those that include high thermal fluctuation, atomic oxygen, and high-energy ionizing radiation. However, conventional or state-of-the-art electroactive materials like lead zirconate titanate, poly(vinylidene fluoride), and carbon nanotube (CNT)-doped polyimides have limitations on use in those extreme applications. Theoretical studies have shown that boron nitride nanotubes (BNNTs) have strength-to-weight ratios comparable to those of CNTs, excellent high-temperature stability (to 800 C in air), large electroactive characteristics, and excellent neutron radiation shielding capability. In this study, we demonstrated the experimental electroactive characteristics of BNNTs in novel multifunctional electroactive nanocomposites. Upon application of an external electric field, the 2 wt % BNNT/polyimide composite was found to exhibit electroactive strain composed of a superposition of linear piezoelectric and nonlinear electrostrictive components. When the BNNTs were aligned by stretching the 2 wt % BNNT/polyimide composite, electroactive characteristics increased by about 460% compared to the nonstretched sample. An all-nanotube actuator consisting of a BNNT buckypaper layer between two single-walled carbon nanotube buck-paper electrode layers was found to have much larger electroactive properties. The additional neutron radiation shielding properties and ultraviolet/visible/near-infrared optical properties of the BNNT composites make them excellent candidates for use in the extreme environments of space missions. utilizing the unique characteristics of BNNTs.

  14. Biocompatible Electroactive Tetra(aniline)-Conjugated Peptide Nanofibers for Neural Differentiation.

    Science.gov (United States)

    Arioz, Idil; Erol, Ozlem; Bakan, Gokhan; Dikecoglu, F Begum; Topal, Ahmet E; Urel, Mustafa; Dana, Aykutlu; Tekinay, Ayse B; Guler, Mustafa O

    2018-01-10

    Peripheral nerve injuries cause devastating problems for the quality of patients' lives, and regeneration following damage to the peripheral nervous system is limited depending on the degree of the damage. Use of nanobiomaterials can provide therapeutic approaches for the treatment of peripheral nerve injuries. Electroactive biomaterials, in particular, can provide a promising cure for the regeneration of nerve defects. Here, a supramolecular electroactive nanosystem with tetra(aniline) (TA)-containing peptide nanofibers was developed and utilized for nerve regeneration. Self-assembled TA-conjugated peptide nanofibers demonstrated electroactive behavior. The electroactive self-assembled peptide nanofibers formed a well-defined three-dimensional nanofiber network mimicking the extracellular matrix of the neuronal cells. Neurite outgrowth was improved on the electroactive TA nanofiber gels. The neural differentiation of PC-12 cells was more advanced on electroactive peptide nanofiber gels, and these biomaterials are promising for further use in therapeutic neural regeneration applications.

  15. Electro-active bio-films: formation, characterization and mechanisms

    International Nuclear Information System (INIS)

    Parot, Sandrine

    2007-01-01

    Some bacteria, which are able to exchange electrons with a conductive material without mediator form on conductive surfaces electro-active bio-films. This bacterial property has been recently discovered (2001). Objectives of this work are to develop electro-active bio-films in various natural environments from indigenous flora, then through complementary electrochemical techniques (chrono-amperometry and cyclic voltammetry), to evaluate electro-activity of isolates coming from so-formed bio-films and to characterize mechanisms of electron transfer between bacteria and materials. First, electro-active bio-films have been developed under chrono-amperometry in garden compost and in water coming from Guyana mangrove. These bio-films were respectively able to use an electrode as electron acceptor (oxidation) or as electron donor (reduction). In compost, results obtained in chrono-amperometry and cyclic voltammetry suggest a two-step electron transfer: slow substrate consumption, then rapid electron transfer between bacteria and the electrode. Thereafter, the ability to reduce oxygen was demonstrated with cyclic voltammetry for facultative aerobic isolates from compost bio-films (Enterobacter spp. and Pseudomonas spp.) and for aerobic isolates obtained from marine electro-active bio-films (Roseobacter spp. in majority). Finally, bio-films inducing current increase in chrono-amperometry were developed in bioreactor with synthetic medium from a pure culture of isolates. Hence, for the first time, electro-activity of several anaerobic strains of Geobacter bremensis isolated from compost bio-films was highlighted. (author) [fr

  16. Multilayer Electroactive Polymer Composite Material Comprising Carbon Nanotubes

    Science.gov (United States)

    Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

    2009-01-01

    An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

  17. Pull-in and wrinkling instabilities of electroactive dielectric actuators

    International Nuclear Information System (INIS)

    De Tommasi, D; Puglisi, G; Zurlo, G; Saccomandi, G

    2010-01-01

    We propose a model to analyse the insurgence of pull-in and wrinkling failures in electroactive thin films. We take into consideration both cases of voltage and charge control, the role of pre-stretch and the size of activated regions, which are all crucial factors in technological applications of electroactive polymers (EAPs). Based on simple geometrical and material assumptions we deduce an explicit analytical description of these phenomena, allowing a clear physical interpretation of different failure mechanisms such as the occurrence of pull-in and wrinkling. Despite our simple assumptions, the comparison with experiments shows a good qualitative and, interestingly, quantitative agreement. In particular our model shows, in accordance with experiments, the existence of different optimal pre-stretch values, depending on the choice of the actuating parameter of the EAP.

  18. Pull-in and wrinkling instabilities of electroactive dielectric actuators

    Energy Technology Data Exchange (ETDEWEB)

    De Tommasi, D; Puglisi, G; Zurlo, G [Dipartimento di Ingegneria Civile e Ambientale, Politecnico di Bari, 70125 Bari (Italy); Saccomandi, G [Dipartimento di Ingegneria Industriale, Universita degli Studi di Perugia, 06125 Perugia (Italy)

    2010-08-18

    We propose a model to analyse the insurgence of pull-in and wrinkling failures in electroactive thin films. We take into consideration both cases of voltage and charge control, the role of pre-stretch and the size of activated regions, which are all crucial factors in technological applications of electroactive polymers (EAPs). Based on simple geometrical and material assumptions we deduce an explicit analytical description of these phenomena, allowing a clear physical interpretation of different failure mechanisms such as the occurrence of pull-in and wrinkling. Despite our simple assumptions, the comparison with experiments shows a good qualitative and, interestingly, quantitative agreement. In particular our model shows, in accordance with experiments, the existence of different optimal pre-stretch values, depending on the choice of the actuating parameter of the EAP.

  19. Self-assembling electroactive hydrogels for flexible display technology

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Scott L; Wong, Kok Hou; Ladouceur, Francois [School of Electrical Engineering and Telecommunications, University of NSW, Sydney, NSW, 2052 (Australia); Thordarson, Pall, E-mail: f.ladouceur@unsw.edu.a [School of Chemistry, University of NSW, Sydney, NSW, 2052 (Australia)

    2010-12-15

    We have assessed the potential of self-assembling hydrogels for use in conformal displays. The self-assembling process can be used to alter the transparency of the material to all visible light due to scattering by fibres. The reversible transition is shown to be of low energy by differential scanning calorimetry. For use in technology it is imperative that this transition is controlled electrically. We have thus synthesized novel self-assembling hydrogelator molecules which contain an electroactive group. The well-known redox couple of anthraquinone/anthrahydroquinone has been used as the hydrophobic component for a series of small molecule gelators. They are further functionalized with peptide combinations of L-phenylalanine and glycine to provide the hydrophilic group to complete 'head-tail' models of self-assembling gels. The gelation and electroactive characteristics of the series were assessed. Cyclic voltammetry shows the reversible redox cycle to be only superficially altered by functionalization. Additionally, spectroelectrochemical measurements show a reversible transparency and colour change induced by the redox process.

  20. Self-assembling electroactive hydrogels for flexible display technology

    International Nuclear Information System (INIS)

    Jones, Scott L; Wong, Kok Hou; Ladouceur, Francois; Thordarson, Pall

    2010-01-01

    We have assessed the potential of self-assembling hydrogels for use in conformal displays. The self-assembling process can be used to alter the transparency of the material to all visible light due to scattering by fibres. The reversible transition is shown to be of low energy by differential scanning calorimetry. For use in technology it is imperative that this transition is controlled electrically. We have thus synthesized novel self-assembling hydrogelator molecules which contain an electroactive group. The well-known redox couple of anthraquinone/anthrahydroquinone has been used as the hydrophobic component for a series of small molecule gelators. They are further functionalized with peptide combinations of L-phenylalanine and glycine to provide the hydrophilic group to complete 'head-tail' models of self-assembling gels. The gelation and electroactive characteristics of the series were assessed. Cyclic voltammetry shows the reversible redox cycle to be only superficially altered by functionalization. Additionally, spectroelectrochemical measurements show a reversible transparency and colour change induced by the redox process.

  1. Biodegradable electroactive materials for tissue engineering applications

    Science.gov (United States)

    Guimard, Nathalie Kathryn

    This dissertation focuses on the development of biomaterials that could be used to enhance the regeneration of severed peripheral nerves. These materials were designed to be electroactive, biodegradable, and biocompatible. To render the materials electroactive the author chose to incorporate conducting polymer (CP) units into the materials. Because CPs are inherently non-degradable, the key challenge was to create a CP-based material that was also biodegradable. Two strategies were explored to generate a biodegradable CP-based material. The first strategy centered around the incorporation of both electroactive and biodegradable subunits into a copolymer system. In the context of this approach, two bis(methoxyquaterthiophene)-co-adipic acid polyester (QAPE) analogues were successfully synthesized, one through polycondensation (giving undoped QAPE) and the second through oxidative polymerization (giving doped QAPE-2). QAPE was found to be electroactive by cyclic voltammetry, bioerodible, and cytocompatible with Schwann cells. QAPE was doped with ferric perchlorate, although only a low doping percentage was realized (˜8%). Oxidative polymerization of a bis(bithiophene) adipate permitted the direct synthesis of doped QAPE-2, which was found to have a higher doping level (˜24%). The second strategy pursued with the goal of generating an electroactive biodegradable material involved covalently immobilizing low molecular weight polythiophene chains onto the surface of crosslinked hyaluronic acid (HA) films. HA films are not only biodegradable and biocompatible, but they also provide mechanical integrity to bilayer systems. Dicyclocarbodiimide coupling of carboxylic acids to HA alcohol groups was used to functionalize HA films. The HA-polythiophene composite is still in the early stages of development. However, to date, thiophene has been successfully immobilized at the surface of HA films with a high degree of substitution. The author has also shown that thiophene

  2. Electro-Active Polymer (EAP) Actuators for Planetary Applications

    Science.gov (United States)

    Bar-Cohen, Y.; Leary, S.; Shahinpoor, M.; Harrison, J. O.; Smith, J.

    1999-01-01

    NASA is seeking to reduce the mass, size, consumed power, and cost of the instrumentation used in its future missions. An important element of many instruments and devices is the actuation mechanism and electroactive polymers (EAP) are offering an effective alternative to current actuators. In this study, two families of EAP materials were investigated, including bending ionomers and longitudinal electrostatically driven elastomers. These materials were demonstrated to effectively actuate manipulation devices and their performance is being enhanced in this on-going study. The recent observations are reported in this paper, include the operation of the bending-EAP at conditions that exceed the harsh environment on Mars, and identify the obstacles that its properties and characteristics are posing to using them as actuators. Analysis of the electrical characteristics of the ionomer EAP showed that it is a current driven material rather than voltage driven and the conductivity distribution on the surface of the material greatly influences the bending performance. An accurate equivalent circuit modeling of the ionomer EAP performance is essential for the design of effective drive electronics. The ionomer main limitations are the fact that it needs to be moist continuously and the process of electrolysis that takes place during activation. An effective coating technique using a sprayed polymer was developed extending its operation in air from a few minutes to about four months. The coating technique effectively forms the equivalent of a skin to protect the moisture content of the ionomer. In parallel to the development of the bending EAP, the development of computer control of actuated longitudinal EAP has been pursued. An EAP driven miniature robotic arm was constructed and it is controlled by a MATLAB code to drop and lift the arm and close and open EAP fingers of a 4-finger gripper. Keywords: Miniature Robotics, Electroactive Polymers, Electroactive Actuators, EAP

  3. Electroactive monolithic μchip for electrochemically-responsive chromatography

    OpenAIRE

    Power, Aoife

    2013-01-01

    The EMμ project’s focus is ultimately, the development of an electroactive monolith that can be incorporated into a microfluidic system for electroanalytical applications such as sensing and electrochemically-controlled extractions and separations. To date our have made several significant advances to achieving this end goal. Firstly a facile fabrication method which allows for the production of fully disposable, gasket–free thin–layer cells suitable for EMμ was developed. A polydimethylsilox...

  4. Injectable, degradable, electroactive nanocomposite hydrogels containing conductive polymer nanoparticles for biomedical applications.

    Science.gov (United States)

    Wang, Qinmei; Wang, Qiong; Teng, Wei

    2016-01-01

    Injectable electroactive hydrogels (eGels) are promising in regenerative medicine and drug delivery, however, it is still a challenge to obtain such hydrogels simultaneously possessing other properties including uniform structure, degradability, robustness, and biocompatibility. An emerging strategy to endow hydrogels with desirable properties is to incorporate functional nanoparticles in their network. Herein, we report the synthesis and characterization of an injectable hydrogel based on oxidized alginate (OA) crosslinking gelatin reinforced by electroactive tetraaniline-graft-OA nanoparticles (nEOAs), where nEOAs are expected to impart electroactivity besides reinforcement without significantly degrading the other properties of hydrogels. Assays of transmission electron microscopy, (1)H nuclear magnetic resonance, and dynamic light scattering reveal that EOA can spontaneously and quickly self-assemble into robust nanoparticles in water, and this nanoparticle structure can be kept at pH 3~9. Measurement of the gel time by rheometer and the stir bar method confirms the formation of the eGels, and their gel time is dependent on the weight content of nEOAs. As expected, adding nEOAs to hydrogels does not cause the phase separation (scanning electron microscopy observation), but it improves mechanical strength up to ~8 kPa and conductivity up to ~10(-6) S/cm in our studied range. Incubating eGels in phosphate-buffered saline leads to their further swelling with an increase of water content <6% and gradual degradation. When growing mesenchymal stem cells on eGels with nEOA content ≤14%, the growth curves and morphology of cells were found to be similar to that on tissue culture plastic; when implanting these eGels on a chick chorioallantoic membrane for 1 week, mild inflammation response appeared without any other structural changes, indicating their good in vitro and in vivo biocompatibility. With injectability, uniformity, degradability, electroactivity, relative

  5. Injectable, degradable, electroactive nanocomposite hydrogels containing conductive polymer nanoparticles for biomedical applications

    Directory of Open Access Journals (Sweden)

    Wang QM

    2016-01-01

    . When growing mesenchymal stem cells on eGels with nEOA content ≤14%, the growth curves and morphology of cells were found to be similar to that on tissue culture plastic; when implanting these eGels on a chick chorioallantoic membrane for 1 week, mild inflammation response appeared without any other structural changes, indicating their good in vitro and in vivo biocompatibility. With injectability, uniformity, degradability, electroactivity, relative robustness, and biocompatibility, these eGels may have a huge potential as scaffolds for tissue regeneration and matrix for stimuli responsive drug release. Keywords: injectability, electroactivity, nanocomposite hydrogels, reinforcement, tetraaniline, alginate, gelatin

  6. An Electromechanical Model for a Dielectric ElectroActive Polymer Generator

    DEFF Research Database (Denmark)

    Dimopoulos, Emmanouil; Trintis, Ionut; Munk-Nielsen, Stig

    2013-01-01

    Smart electroactive materials have attracted much of the scientific interest over the past few years, as they reflect a quite promising alternative to conservative approaches used nowadays in various transducer applications. Especially Dielectric ElectroActive Polymers (DEAPs), which are constantly...

  7. Considerations for Contractile Electroactive Materials and Actuators

    International Nuclear Information System (INIS)

    Rasmussen, Lenore; Schramm, David; Meixler, Lewis D.; Gentile, Charles A.; Ascione, George; Tilson, Carl; Pagdon, Kelsey

    2010-01-01

    Ras Labs produces electroactive polymer (EAP) based materials and actuators that bend, swell, ripple, and now contract (new development) with low electric input. In addition, Ras Labs produces EAP materials that quickly contract and expand, repeatedly, by reversing the polarity of the electric input. These recent developments are important attributes in the field of electroactivity because of the ability of contraction and contraction-expansion to produce biomimetric motion. The mechanism of contraction is not well understood. Radionuclide-labeled experiments were conducted to determine the mechanisms during contraction of these EAPs.

  8. Structural health monitoring system/method using electroactive polymer fibers

    Science.gov (United States)

    Scott-Carnell, Lisa A. (Inventor); Siochi, Emilie J. (Inventor)

    2013-01-01

    A method for monitoring the structural health of a structure of interest by coupling one or more electroactive polymer fibers to the structure and monitoring the electroactive responses of the polymer fiber(s). Load changes that are experienced by the structure cause changes in the baseline responses of the polymer fiber(s). A system for monitoring the structural health of the structure is also provided.

  9. Recent Progress on Cellulose-Based Electro-Active Paper, Its Hybrid Nanocomposites and Applications.

    Science.gov (United States)

    Khan, Asif; Abas, Zafar; Kim, Heung Soo; Kim, Jaehwan

    2016-07-26

    We report on the recent progress and development of research into cellulose-based electro-active paper for bending actuators, bioelectronics devices, and electromechanical transducers. The cellulose electro-active paper is characterized in terms of its biodegradability, chirality, ample chemically modifying capacity, light weight, actuation capability, and ability to form hybrid nanocomposites. The mechanical, electrical, and chemical characterizations of the cellulose-based electro-active paper and its hybrid composites such as blends or coatings with synthetic polymers, biopolymers, carbon nanotubes, chitosan, and metal oxides, are explained. In addition, the integration of cellulose electro-active paper is highlighted to form various functional devices including but not limited to bending actuators, flexible speaker, strain sensors, energy harvesting transducers, biosensors, chemical sensors and transistors for electronic applications. The frontiers in cellulose paper devices are reviewed together with the strategies and perspectives of cellulose electro-active paper and cellulose nanocomposite research and applications.

  10. Recent Progress on Cellulose-Based Electro-Active Paper, Its Hybrid Nanocomposites and Applications

    Directory of Open Access Journals (Sweden)

    Asif Khan

    2016-07-01

    Full Text Available We report on the recent progress and development of research into cellulose-based electro-active paper for bending actuators, bioelectronics devices, and electromechanical transducers. The cellulose electro-active paper is characterized in terms of its biodegradability, chirality, ample chemically modifying capacity, light weight, actuation capability, and ability to form hybrid nanocomposites. The mechanical, electrical, and chemical characterizations of the cellulose-based electro-active paper and its hybrid composites such as blends or coatings with synthetic polymers, biopolymers, carbon nanotubes, chitosan, and metal oxides, are explained. In addition, the integration of cellulose electro-active paper is highlighted to form various functional devices including but not limited to bending actuators, flexible speaker, strain sensors, energy harvesting transducers, biosensors, chemical sensors and transistors for electronic applications. The frontiers in cellulose paper devices are reviewed together with the strategies and perspectives of cellulose electro-active paper and cellulose nanocomposite research and applications.

  11. Recent Progress on Cellulose-Based Electro-Active Paper, Its Hybrid Nanocomposites and Applications

    OpenAIRE

    Asif Khan; Zafar Abas; Heung Soo Kim; Jaehwan Kim

    2016-01-01

    We report on the recent progress and development of research into cellulose-based electro-active paper for bending actuators, bioelectronics devices, and electromechanical transducers. The cellulose electro-active paper is characterized in terms of its biodegradability, chirality, ample chemically modifying capacity, light weight, actuation capability, and ability to form hybrid nanocomposites. The mechanical, electrical, and chemical characterizations of the cellulose-based electro-active pa...

  12. Designing components using smartMOVE electroactive polymer technology

    Science.gov (United States)

    Rosenthal, Marcus; Weaber, Chris; Polyakov, Ilya; Zarrabi, Al; Gise, Peter

    2008-03-01

    Designing components using SmartMOVE TM electroactive polymer technology requires an understanding of the basic operation principles and the necessary design tools for integration into actuator, sensor and energy generation applications. Artificial Muscle, Inc. is collaborating with OEMs to develop customized solutions for their applications using smartMOVE. SmartMOVE is an advanced and elegant way to obtain almost any kind of movement using dielectric elastomer electroactive polymers. Integration of this technology offers the unique capability to create highly precise and customized motion for devices and systems that require actuation. Applications of SmartMOVE include linear actuators for medical, consumer and industrial applications, such as pumps, valves, optical or haptic devices. This paper will present design guidelines for selecting a smartMOVE actuator design to match the stroke, force, power, size, speed, environmental and reliability requirements for a range of applications. Power supply and controller design and selection will also be introduced. An overview of some of the most versatile configuration options will be presented with performance comparisons. A case example will include the selection, optimization, and performance overview of a smartMOVE actuator for the cell phone camera auto-focus and proportional valve applications.

  13. Electroactive and Optoelectronically Active Graphene Nanofilms

    DEFF Research Database (Denmark)

    Chi, Qijin

    As an atomic-scale-thick two-dimensional material, graphene has emerged as one of the most miracle materials and has generated intensive interest in physics, chemistry and even biology in the last decade [1, 2]. Nanoscale engineering and functionalization of graphene is a crucial step for many...... applications ranging from catalysis, electronic devices, sensors to advanced energy conversion and storage [3]. This talk highlights our recent studies on electroactive and optoelectronically active graphene ultrathin films for chemical sensors and energy technology. The presentation includes a general theme...... for functionalization of graphene nanosheets, followed by showing several case studies. Our systems cover redox-active nanoparticles, electroactive supramolecular ensembles and redox enzymes which are integrated with graphene nanosheets as building blocks for the construction of functional thin films or graphene papers....

  14. Observation of nanometer-sized electro-active defects in insulating layers by fluorescence microscopy and electrochemistry.

    Science.gov (United States)

    Renault, Christophe; Marchuk, Kyle; Ahn, Hyun S; Titus, Eric J; Kim, Jiyeon; Willets, Katherine A; Bard, Allen J

    2015-06-02

    We report a method to study electro-active defects in passivated electrodes. This method couples fluorescence microscopy and electrochemistry to localize and size electro-active defects. The method was validated by comparison with a scanning probe technique, scanning electrochemical microscopy. We used our method for studying electro-active defects in thin TiO2 layers electrodeposited on 25 μm diameter Pt ultramicroelectrodes (UMEs). The permeability of the TiO2 layer was estimated by measuring the oxidation of ferrocenemethanol at the UME. Blocking of current ranging from 91.4 to 99.8% was achieved. Electro-active defects with an average radius ranging between 9 and 90 nm were observed in these TiO2 blocking layers. The distribution of electro-active defects over the TiO2 layer is highly inhomogeneous and the number of electro-active defect increases for lower degree of current blocking. The interest of the proposed technique is the possibility to quickly (less than 15 min) image samples as large as several hundreds of μm(2) while being able to detect electro-active defects of only a few tens of nm in radius.

  15. An electro-conductive fluid as a responsive implant for the controlled stimuli-release of diclofenac sodium.

    Science.gov (United States)

    Bijukumar, Divya; Choonara, Yahya E; Kumar, Pradeep; du Toit, Lisa C; Pillay, Viness

    2016-11-01

    The purpose of this study was to develop an electro-responsive co-polymeric (ERP) implantable gel from polyethylene glycol (PEG), sodium polystyrene sulphonate (NaPss), polyvinyl alcohol (PVA), and diethyl acetomidomalonate (DAA) for electro-liberation of the model drug diclofenac sodium. Various physicochemical and physicomechanical characterization tests were undertaken on the synthesized drug-free gel (ERP G1) and drug-loaded gel (ERP G2). The ability of the gel to release diclofenac sodium following electrical stimulation was evaluated using a galvanostat while Molecular Mechanics (MM) simulations were performed to elucidate the experimental mechanisms. A stable electro-active gel exhibiting superior cycling stability was produced with desirable rheological properties, rigidity (BHN = 35.4 N ± 0.33 N/mm 2 ; resilience = 10.91 ± 0.11%), thermal properties (T g  ≈ 70 °C; T c  ≈ 200 °C) and homogeneous morphology. "ON-OFF" pursatile gradual drug release (37-94% from t 30 min -t 180   min ) kinetics was observed upon applying electric stimulation intermittently, indicating that drug release from the gel was electrically controlled. Overall, the galvanometric and MM evaluation ascertained the suitability of the PEG/NaPss/PVA ERP-Gel for application as a subcutaneously injectable drug delivery implant.

  16. The Jellyfish: smart electro-active polymers for an autonomous distributed sensing node

    Science.gov (United States)

    Blottman, John B.; Richards, Roger T.

    2006-05-01

    The US Navy has recently placed emphasis on deployable, distributed sensors for Force Protection, Anti-Terrorism and Homeland Defense missions. The Naval Undersea Warfare Center has embarked on the development of a self-contained deployable node that is composed of electro-active polymers (EAP) for use in a covert persistent distributed surveillance system. Electro-Active Polymers (EAP) have matured to a level that permits their application in energy harvesting, hydrophones, electro-elastic actuation and electroluminescence. The problem to resolve is combining each of these functions into an autonomous sensing platform. The concept presented here promises an operational life several orders of magnitude beyond what is expected of a Sonobuoy due to energy conservation and harvesting, and at a reasonable cost. The embodiment envisioned is that of a deployed device resembling a jellyfish, made in most part of polymers, with the body encapsulating the necessary electronic processing and communications package and the tentacles of the jellyfish housing the sonar sensors. It will be small, neutrally buoyant, and will survey the water column much in the manner of a Cartesian Diver. By using the Electro-Active Polymers as artificial muscles, the motion of the jellyfish can be finely controlled. An increased range of detection and true node autonomy is achieved through volumetric array beamforming to focus the direction of interrogation and to null-out extraneous ambient noise.

  17. Effect of solution chemistry on the characteristics of hydrothermally grown WO_3 for electroactive applications

    International Nuclear Information System (INIS)

    Christou, K.; Louloudakis, D.; Vernardou, D.; Savvakis, C.; Katsarakis, N.; Koudoumas, E.; Kiriakidis, G.

    2015-01-01

    Hydrothermally grown tungsten trioxide coatings were prepared at 95 °C using different metal sulfates. Morphology of the oxides was altered from grains to flower- and urchin-like structures using potassium sulfate, sodium sulfate and lithium sulfate, respectively. The flower-like structures presented the highest deintercalated charge, 35 mC cm"−"2 with time response of 96 s. In addition, they indicated a charge transfer resistance across the tungsten trioxide–electrolyte interface of 752 Ω. These outcomes imply that they are promising candidates for electroactive applications. - Highlights: • Hydrothermally grown WO_3 coatings with controlled properties. • The choice of metal sulfate is important in determining their properties. • Flower-like hexagonal WO_3 structures for electroactive applications.

  18. Cellulose Electro-Active Paper: From Discovery to Technology Applications

    Science.gov (United States)

    Abas, Zafar; Kim, Heung Soo; Kim, Jaehwan; Kim, Joo-Hyung

    2014-09-01

    Cellulose electro-active paper (EAPap) is an attractive material of electro-active polymers (EAPs) family due to its smart characteristics. EAPap is thin cellulose film coated with metal electrodes on both sides. Its large displacement output, low actuation voltage and low power consumption can be used for biomimetic sensors/actuators and electromechanical system. Because cellulose EAPap is ultra-lightweight, easy to manufacture, inexpensive, biocompatible, and biodegradable, it has been employed for many applications such as bending actuator, vibration sensor, artificial muscle, flexible speaker, and can be advantageous in areas such as micro-insect robots, micro-flying objects, microelectromechanical systems, biosensors, and flexible displays.

  19. An electroactive polymer energy harvester for wireless sensor networks

    International Nuclear Information System (INIS)

    McKay, T G; Rosset, S; Shea, H; Anderson, I A

    2013-01-01

    This paper reports the design, fabrication, and testing of a soft electroactive polymer power generator that has a volume of 1cm 3 . The generator provides an opportunity to harvest energy from environmental sources to power wireless sensor networks because it can harvest from low frequency motions, is compact, and lightweight. Electroactive polymers are highly stretchable variable capacitors. Electrical energy is produced when the deformation of a stretched, charged electroactive polymer is relaxed; like-charges are compressed together and opposite-charges are pushed apart, resulting in an increased voltage. Although electroactive polymers have impressively displayed energy densities as high as 550 mJ/g, they have been based on films with thicknesses of tens to hundreds of micrometers, thus a generator covering a large area would be required to provide useful power. Energy harvesters covering large areas are inconvenient to deploy in a wireless sensor network with a large number of nodes, so a generator that is compact in all three dimensions is required. In this work we fabricated a generator that can fit within a 11×11×9 mm envelope by stacking 42, 11mm diameter generator films on top of each other. When compressed cyclically at a rate of 0.5 Hz our generator produced 300 uW of power which is a sufficient amount of power for a low power wireless sensor node. The combination of our generator's small form factor and ability to harvest useful energy from low frequency motions provides an opportunity to deploy large numbers of wireless sensor nodes without the need for periodic, costly battery replacement

  20. Wirelessly driven electro-active paper actuator made with cellulose–polypyrrole–ionic liquid and dipole rectenna

    International Nuclear Information System (INIS)

    Yang, Sang Yeol; Mahadeva, Suresha K; Kim, Jaehwan

    2010-01-01

    This paper reports a wirelessly driven electro-active paper actuator that consists of a dipole rectenna array, a power control circuit and two cellulose–polypyrrole–ionic liquid (CPIL) electro-active paper actuators. The CPIL nanocomposite actuator was fabricated by incorporating nanoscaled PPy onto cellulose by an in situ polymerization technique, which was followed by activation in a room temperature ionic liquid. The CPIL actuator shows its maximum bending displacement of 10 mm at an ambient humidity condition with 30 mW electrical power consumption. The CPIL actuator is very stable in its actuator performance. The dipole rectenna array receives microwaves and converts them to dc power so as to wirelessly supply power to the actuators. Three flexible dipole rectenna arrays are designed, manufactured and characterized. The rectenna array that has nine rectenna elements generates the maximum power of 75 mW. This power was used to successfully activate the two CPIL actuators and the control circuit. Detailed fabrication and characterization of the CPIL actuator and the dipole rectenna array as well as the control circuit are explained

  1. Cellulose Electro-Active Paper: From Discovery to Technology Applications

    Directory of Open Access Journals (Sweden)

    Zafar eAbas

    2014-09-01

    Full Text Available Cellulose electro-active paper (EAPap is an attractive material of electro-active polymers (EAPs family due to its smart characteristics. EAPap is thin cellulose film coated with metal electrodes on both sides. Its large displacement output, low actuation voltage and low power consumption can be used for biomimetic sensors/actuators and electromechanical system. Because cellulose EAPap is ultra-lightweight, easy to manufacture, inexpensive, biocompatible, and biodegradable, it has been employed for many applications such as bending actuator, vibration sensor, artificial muscle, flexible speaker, and can be advantageous in areas such as micro-insect robots, micro-flying objects, microelectromechanical systems, biosensors, and flexible displays.

  2. Large scale processing of dielectric electroactive polymers

    DEFF Research Database (Denmark)

    Vudayagiri, Sindhu

    Efficient processing techniques are vital to the success of any manufacturing industry. The processing techniques determine the quality of the products and thus to a large extent the performance and reliability of the products that are manufactured. The dielectric electroactive polymer (DEAP...

  3. Electroactive Polymer (EAP) Actuation of Mechanisms and Robotic Devices

    Science.gov (United States)

    Bar-Cohen, Y.; Leary, S.; Harrison, J.; Smith, J.

    1999-01-01

    Actuators are responsible to the operative capability of manipulation systems and robots. In recent years, electroactive polymers (EAP) have emerged as potential alternative to conventional actuators.

  4. Electrochemical energy storage device based on carbon dioxide as electroactive species

    Science.gov (United States)

    Nemeth, Karoly; van Veenendaal, Michel Antonius; Srajer, George

    2013-03-05

    An electrochemical energy storage device comprising a primary positive electrode, a negative electrode, and one or more ionic conductors. The ionic conductors ionically connect the primary positive electrode with the negative electrode. The primary positive electrode comprises carbon dioxide (CO.sub.2) and a means for electrochemically reducing the CO.sub.2. This means for electrochemically reducing the CO.sub.2 comprises a conductive primary current collector, contacting the CO.sub.2, whereby the CO.sub.2 is reduced upon the primary current collector during discharge. The primary current collector comprises a material to which CO.sub.2 and the ionic conductors are essentially non-corrosive. The electrochemical energy storage device uses CO.sub.2 as an electroactive species in that the CO.sub.2 is electrochemically reduced during discharge to enable the release of electrical energy from the device.

  5. Electrochemical performance of electroactive poly(amic acid)-Cu{sup 2+} composites

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Ying [Alan G. MacDiarmid Institute, College of Chemistry, Jilin University, Changchun, 130012 (China); Li, Fangfei [State Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China); Hanlon, Ashley M.; Berda, Erik B. [Department of Chemistry and Materials Science Program, University of New Hampshire, Durham, New Hampshire 03824 (United States); Liu, Xincai; Wang, Ce [Alan G. MacDiarmid Institute, College of Chemistry, Jilin University, Changchun, 130012 (China); Chao, Danming, E-mail: chaodanming@jlu.edu.cn [Alan G. MacDiarmid Institute, College of Chemistry, Jilin University, Changchun, 130012 (China)

    2017-01-15

    Graphical abstract: Electroactive poly(amic acid)-Cu{sup 2+} (EPAA-Cu) composites on the substrates have been prepared, whose electrochemical properties, including electroactivity, electrochromism and anticorrosion, reveal drastic enhancement after incorporation of Cu{sup 2+} ions. - Highlights: • The electroactive poly(amic acid)-Cu{sup 2+} (EPAA-Cu) composites were prepared. • A significant current enhancement phenomenon of EPAA-Cu/ITO electrodes was observed. • EPAA-Cu/ITO electrochromic electrodes reveals a shorter switching times. • Excellent corrosive protection for the CS was achieved by incorporating Cu{sup 2+} ions. - Abstract: Electroactive poly(amic acid)-Cu{sup 2+} (EPAA-Cu) composites on substrates were successfully prepared via nucleophilic polycondensation followed by the use of an immersing method. Analysis of the structure properties of EPAA-Cu composites was performed using scanning electron microscopy (SEM), X-ray photoelectron spectra (XPS) and Fourier-transform infrared spectra (FTIR). A significant current enhancement phenomenon of EPAA-Cu/ITO electrodes was found as evident from cyclic voltammetry (CV) measurements. In addition, Cu{sup 2+} ions were incorporated into the composites and had a positive effect on their electrochromic behaviors decreasing their switching times. The anticorrosive performance of EPAA-Cu composites coatings on the carbon steel in 3.5 wt% NaCl solution were also investigated in detail using tafel plots analysis and electrochemical impedance spectroscopy. The anticorrosive ability of these coatings significantly enhanced through the incorporation of Cu{sup 2+} ions.

  6. Enabling novel planetary and terrestrial mechanisms using electroactive materials at the JPL's NDEAA Lab

    Science.gov (United States)

    Bar-Cohen, Yoseph; Sherrit, Stewart; Bao, Xiaoqi; Chang, Zensheu; Lih, Shyh-Shiuh

    2004-01-01

    Increasingly, electroactive materials are used to produce acutators, sensors, displays and other elements of mechanisms and devices. In recognition of the potential of these materials, research at the JPL's NDEAA Lab have led to many novel space and terrestrial applications. This effort involves mostly the use of piezoelectric and electroactive polymers (EAP).

  7. Energy Harvesting Cycles of Dielectric ElectroActive Polymer Generators

    DEFF Research Database (Denmark)

    Dimopoulos, Emmanouil; Trintis, Ionut; Munk-Nielsen, Stig

    2012-01-01

    Energy harvesting via Dielectric ElectroActive Polymer (DEAP) generators has attracted much of the scientific interest over the past few years, mainly due to the advantages that these smart materials offer against competing technologies, as electromagnetic generators and piezoelectrics. Their hig......Energy harvesting via Dielectric ElectroActive Polymer (DEAP) generators has attracted much of the scientific interest over the past few years, mainly due to the advantages that these smart materials offer against competing technologies, as electromagnetic generators and piezoelectrics....... Their higher energy density, superior low-speed performance, light-weighted nature as well as their shapely structure have rendered DEAPs candidate solutions for various actuation and energy harvesting applications. In this paper, a thoroughly analysis of all energy harvesting operational cycles of a DEAP...

  8. Electroactive subwavelength gratings (ESWGs) from conjugated polymers for color and intensity modulation

    Science.gov (United States)

    Bhuvana, Thiruvelu; Kim, Byeonggwan; Yang, Xu; Shin, Haijin; Kim, Eunkyoung

    2012-05-01

    Subwavelength gratings with electroactive polymers such as poly(3-hexylthiophene) (P3HT) and poly(3,4-propylenedioxythiophene-phenylene) (P(ProDOT-Ph)) controlled the color intensity for various visible colors of diffracted light in a single device. Under the illumination of a white light, at a fixed angle of incidence, the color intensity of the diffracted light was reversibly switched from the maximum value down to 15% (85% decrease) by applying -2 to 2 V due to electrochemical (EC) reaction. All spectral colors including red, green, and blue were generated by changing the angle of incidence, and the intensity of each color was modulated electrochemically at a single EC device. With electroactive subwavelength gratings (ESWGs) of P3HT, the maximum modulation of the color intensity was observed in the red-yellow quadrant in the CIE color plot, whereas for the ESWGs of P(ProDOT-Ph), the maximum modulation of the color intensity was observed in the yellow-green and green-blue quadrants. Both ESWGs showed a memory effect, keeping their color and intensity even after power was turned off for longer than 40 hours.Subwavelength gratings with electroactive polymers such as poly(3-hexylthiophene) (P3HT) and poly(3,4-propylenedioxythiophene-phenylene) (P(ProDOT-Ph)) controlled the color intensity for various visible colors of diffracted light in a single device. Under the illumination of a white light, at a fixed angle of incidence, the color intensity of the diffracted light was reversibly switched from the maximum value down to 15% (85% decrease) by applying -2 to 2 V due to electrochemical (EC) reaction. All spectral colors including red, green, and blue were generated by changing the angle of incidence, and the intensity of each color was modulated electrochemically at a single EC device. With electroactive subwavelength gratings (ESWGs) of P3HT, the maximum modulation of the color intensity was observed in the red-yellow quadrant in the CIE color plot, whereas for the

  9. Synthesis of biodegradable and electroactive multiblock polylactide and aniline pentamer copolymer for tissue engineering applications.

    Science.gov (United States)

    Huang, Lihong; Zhuang, Xiuli; Hu, Jun; Lang, Le; Zhang, Peibiao; Wang, Yu; Chen, Xuesi; Wei, Yen; Jing, Xiabin

    2008-03-01

    To obtain one biodegradable and electroactive polymer as the scaffold for tissue engineering, the multiblock copolymer PLAAP was designed and synthesized with the condensation polymerization of hydroxyl-capped poly( l-lactide) (PLA) and carboxyl-capped aniline pentamer (AP). The PLAAP copolymer exhibited excellent electroactivity, solubility, and biodegradability. At the same time, as one scaffold material, PLAAP copolymer possesses certain mechanical properties with the tensile strength of 3 MPa, tensile Young 's modulus of 32 MPa, and breaking elongation rate of 95%. We systematically studied the compatibility of PLAAP copolymer in vitro and proved that the electroactive PLAAP copolymer was innocuous, biocompatible, and helpful for the adhesion and proliferation of rat C6 cells. Moreover, the PLAAP copolymer stimulated by electrical signals was demonstrated as accelerating the differentiation of rat neuronal pheochromocytoma PC-12 cells. This biodegradable and electroactive PLAAP copolymer thus possessed the properties in favor of the long-time application in vivo as nerve repair scaffold materials in tissue engineering.

  10. Micro-mechanics of ionic electroactive polymer actuators

    Science.gov (United States)

    Punning, Andres; Põldsalu, Inga; Kaasik, Friedrich; Vunder, Veiko; Aabloo, Alvo

    2015-04-01

    Commonly, modeling of the bending behavior of the ionic electroactive polymer (IEAP) actuators is based on the classical mechanics of cantilever beam. It is acknowledged, that the actuation of the ionic electroactive polymer (IEAP) actuators is symmetric about the centroid - the convex side of the actuator is expanding and the concave side is contracting for exactly the same amount, while the thickness of the actuator remains invariant. Actuating the IEAP actuators and sensors under scanning electron microscope (SEM), in situ, reveals that for some types of them this approach is incorrect. Comparison of the SEM micrographs using the Digital Image Correction (DIC) method results with the precise strain distribution of the IEAP actuators in two directions: in the axial direction, and in the direction of thickness. This information, in turn, points to the physical processes taking place within the electrodes as well as membrane of the trilayer laminate of sub-millimeter thickness. Comparison of the EAP materials, engaged as an actuator as well as a sensor, reveals considerable differences between the micro-mechanics of the two modes.

  11. Influence of conductive electroactive polymer polyaniline on ...

    Indian Academy of Sciences (India)

    Conductive electroactive polymer polyaniline is utilized to substitute conductive additive acetylene black in the LiMn1.95Al0.05O4 cathode for lithium ion batteries. Results show that LiMn1.95Al0.05O4 possesses stable structure and good performance. Percolation theory is used to optimize the content of conductive additive ...

  12. Incorporating catechol into electroactive polypyrrole nanowires on titanium to promote hydroxyapatite formation

    Directory of Open Access Journals (Sweden)

    Zhengao Wang

    2018-03-01

    Full Text Available To improve the osteointegration property of biomedical titanium, nano-architectured electroactive coating was synthesized through the electrochemical polymerization of dopamine and pyrrole. The highly binding affinity of Ca2+ to the catechol moiety of doped dopamine enabled efficient interaction between polypyrrole/polydopamine nanowires and mineral ions. The results indicate that the PPy/PDA nanowires preserved its efficient electro-activity and accelerated the hydroxyapatite deposition in a simulated body fluid. The PPy/PDA nanowires coating could be applied to promote the osteointegration of titanium implant.

  13. Biocompatible, Biodegradable, and Electroactive Polyurethane-Urea Elastomers with Tunable Hydrophilicity for Skeletal Muscle Tissue Engineering.

    Science.gov (United States)

    Chen, Jing; Dong, Ruonan; Ge, Juan; Guo, Baolin; Ma, Peter X

    2015-12-30

    It remains a challenge to develop electroactive and elastic biomaterials to mimic the elasticity of soft tissue and to regulate the cell behavior during tissue regeneration. We designed and synthesized a series of novel electroactive and biodegradable polyurethane-urea (PUU) copolymers with elastomeric property by combining the properties of polyurethanes and conducting polymers. The electroactive PUU copolymers were synthesized from amine capped aniline trimer (ACAT), dimethylol propionic acid (DMPA), polylactide, and hexamethylene diisocyanate. The electroactivity of the PUU copolymers were studied by UV-vis spectroscopy and cyclic voltammetry. Elasticity and Young's modulus were tailored by the polylactide segment length and ACAT content. Hydrophilicity of the copolymer films was tuned by changing DMPA content and doping of the copolymer. Cytotoxicity of the PUU copolymers was evaluated by mouse C2C12 myoblast cells. The myogenic differentiation of C2C12 myoblasts on copolymer films was also studied by analyzing the morphology of myotubes and relative gene expression during myogenic differentiation. The chemical structure, thermal properties, surface morphology, and processability of the PUU copolymers were characterized by NMR, FT-IR, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and solubility testing, respectively. Those biodegradable electroactive elastic PUU copolymers are promising materials for repair of soft tissues such as skeletal muscle, cardiac muscle, and nerve.

  14. Electroactive Ionic Soft Actuators with Monolithically Integrated Gold Nanocomposite Electrodes.

    Science.gov (United States)

    Yan, Yunsong; Santaniello, Tommaso; Bettini, Luca Giacomo; Minnai, Chloé; Bellacicca, Andrea; Porotti, Riccardo; Denti, Ilaria; Faraone, Gabriele; Merlini, Marco; Lenardi, Cristina; Milani, Paolo

    2017-06-01

    Electroactive ionic gel/metal nanocomposites are produced by implanting supersonically accelerated neutral gold nanoparticles into a novel chemically crosslinked ion conductive soft polymer. The ionic gel consists of chemically crosslinked poly(acrylic acid) and polyacrylonitrile networks, blended with halloysite nanoclays and imidazolium-based ionic liquid. The material exhibits mechanical properties similar to that of elastomers (Young's modulus ≈ 0.35 MPa) together with high ionic conductivity. The fabrication of thin (≈100 nm thick) nanostructured compliant electrodes by means of supersonic cluster beam implantation (SCBI) does not significantly alter the mechanical properties of the soft polymer and provides controlled electrical properties and large surface area for ions storage. SCBI is cost effective and suitable for the scaleup manufacturing of electroactive soft actuators. This study reports the high-strain electromechanical actuation performance of the novel ionic gel/metal nanocomposites in a low-voltage regime (from 0.1 to 5 V), with long-term stability up to 76 000 cycles with no electrode delamination or deterioration. The observed behavior is due to both the intrinsic features of the ionic gel (elasticity and ionic transport capability) and the electrical and morphological features of the electrodes, providing low specific resistance (<100 Ω cm -2 ), high electrochemical capacitance (≈mF g -1 ), and minimal mechanical stress at the polymer/metal composite interface upon deformation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. A facile route to the synthesis of anilinic electroactive colloidal hydrogels for neural tissue engineering applications.

    Science.gov (United States)

    Zarrintaj, Payam; Urbanska, Aleksandra M; Gholizadeh, Saman Seyed; Goodarzi, Vahabodin; Saeb, Mohammad Reza; Mozafari, Masoud

    2018-04-15

    An innovative drug-loaded colloidal hydrogel was synthesized for applications in neural interfaces in tissue engineering by reacting carboxyl capped aniline dimer and gelatin molecules. Dexamethasone was loaded into the gelatin-aniline dimer solution as a model drug to form an in situ drug-loaded colloidal hydrogel. The conductivity of the hydrogel samples fluctuated around 10 -5  S/cm which appeared suitable for cellular activities. Cyclic voltammetry was used for electroactivity determination, in which 2 redox states were observed, suggesting that the short chain length and steric hindrance prevented the gel from achieving a fully oxidized state. Rheological data depicted the modulus decreasing with aniline dimer increment due to limited hydrogen bonds accessibility. Though the swelling ratio of pristine gelatin (600%) decreased by the introduction and increasing the concentration of aniline dimer because of its hydrophobic nature, it took the value of 300% at worst, which still seems promising for drug delivery uses. Degradation rate of hydrogel was similarly decreased by adding aniline dimer. Drug release was evaluated in passive and stimulated patterns demonstrating tendency of aniline dimer to form a vesicle that controls the drug release behavior. The optimal cell viability, proper cell attachment and neurite extension was achieved in the case of hydrogel containing 10 wt% aniline dimer. Based on tissue/organ behavior, it was promisingly possible to adjust the characteristics of the hydrogels for an optimal drug release. The outcome of this simple and effective approach can potentially offer additional tunable characteristics for recording and stimulating purposes in neural interfaces. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. Fibronectin adsorption and cell response on electroactive poly(vinylidene fluoride) films

    International Nuclear Information System (INIS)

    Ribeiro, C; Panadero, J A; Sencadas, V; Lanceros-Méndez, S; Tamaño, M N; Moratal, D; Salmerón-Sánchez, M; Gómez Ribelles, J L

    2012-01-01

    Due to the large potential of electroactive materials in novel tissue engineering strategies, the aim of this work is to determine if the crystalline phase and/or the surface electrical charge of electroactive poly(vinylidene fluoride), PVDF, have influence on the biological response in monolayer cell culture. Non-polar α-PVDF and electroactive β-PVDF were prepared. The β-PVDF films were poled by corona discharge to show negative or positive electrical surface charge density. It has been concluded that hydrophilicity of the PVDF substrates depends significantly on crystalline phase and polarity. Furthermore, by means of atomic force microscopy and an enzyme-linked immunosorbent assay test, it has been shown that positive or negative poling strongly influences the behavior of β-PVDF supports with respect to fibronectin (FN) adsorption, varying the exhibition of adhesion ligands of adsorbed FN. Culture of MC3T3-E1 pre-osteoeblasts proved that cell proliferation depends on surface polarity as well. These results open the viability of cell culture stimulation by mechanical deformation of a piezoelectric substrate that results in varying electrical charge densities on the substrate surface. (paper)

  17. The impact of shearing flows on electroactive biofilm formation, structure, and current generation

    Science.gov (United States)

    Jones, A.-Andrew; Buie, Cullen

    2016-11-01

    A special class of bacteria exist that directly produce electricity. First explored in 1911, these electroactive bacteria catalyze hydrocarbons and transport electrons directly to a metallic electron acceptor forming thicker biofilms than other species. Electroactive bacteria biofilms are thicker because they are not limited by transport of oxygen or other terminal electron acceptors. Electroactive bacteria can produce power in fuel cells. Power production is limited in fuel cells by the bacteria's inability to eliminate protons near the insoluble electron acceptor not utilized in the wild. To date, they have not been successfully evolved or engineered to overcome this limit. This limitation may be overcome by enhancing convective mass transport while maintaining substantial biomass within the biofilm. Increasing convective mass transport increases shear stress. A biofilm may respond to increased shear by changing biomass, matrix, or current production. In this study, a rotating disk electrode is used to separate nutrient from physical stress. This phenomenon is investigated using the model electroactive bacterium Geobacter sulfurreducens at nutrient loads comparable to flow-through microbial fuel cells. We determine biofilm structure experimentally by measuring the porosity and calculating the tortuosity from confocal microscope images. Biofilm adaptation for electron transport is quantified using electrical impedance spectroscopy. Our ultimate objective is a framework relating biofilm thickness, porosity, shear stress and current generation for the optimization of bioelectrochemical systems The Alfred P Sloan Foundation MPHD Program.

  18. Surface-confined electroactive molecules for multistate charge storage information.

    Science.gov (United States)

    Mas-Torrent, M; Rovira, C; Veciana, J

    2013-01-18

    Bi-stable molecular systems with potential for applications in binary memory devices are raising great interest for device miniaturization. Particular appealing are those systems that operate with electrical inputs since they are compatible with existing electronic technologies. The processing of higher memory densities in these devices could be accomplished by increasing the number of memory states in each cell, although this strategy has not been much explored yet. Here we highlight the recent advances devoted to the fabrication of charge-storage molecular surface-confined devices exhibiting multiple states. Mainly, this goal has been realized immobilizing a variety (or a combination) of electroactive molecules on a surface, although alternative approaches employing non-electroactive systems have also been described. Undoubtedly, the use of molecules with chemically tunable properties and nanoscale dimensions are raising great hopes for the devices of the future in which molecules can bring new perspectives such as multistability.

  19. Electroactive thermoset shape memory polymer nanocomposite filled with nanocarbon powders

    International Nuclear Information System (INIS)

    Leng, Jinsong; Lan, Xin; Liu, Yanju; Du, Shanyi

    2009-01-01

    This paper concerns an electroactive thermoset styrene-based shape memory polymer (SMP) nanocomposite filled with nanosized (30 nm) carbon powders. With an increase of the incorporated nanocarbon powders of the SMP composite, its glass transition temperature (T g ) decreases and storage modulus increases. Due to the high micro-porosity and homogeneous distributions of nanocarbon powders in the SMP matrix, the SMP composite shows good electrical conductivity with a percolation of about 3.8%. This percolation threshold is slightly lower than that of many other carbon-based conductive polymer composites. Consequently, due to the relatively high electrical conductivity, a sample filled with 10 vol% nanocarbon powders shows a good electroactive shape recovery performance heating by a voltage of 30 V above a transition temperature of 56–69 °C

  20. Controlled-release tablet formulation of isoniazid.

    Science.gov (United States)

    Jain, N K; Kulkarni, K; Talwar, N

    1992-04-01

    Guar (GG) and Karaya gums (KG) alone and in combination with hydroxy-propylmethylcellulose (HPMC) were evaluated as release retarding materials to formulate a controlled-release tablet dosage form of isoniazid (1). In vitro release of 1 from tablets followed non-Fickian release profile with rapid initial release. Urinary excretion studies in normal subjects showed steady-state levels of 1 for 13 h. In vitro and in vivo data correlated (r = 0.9794). The studies suggested the potentiality of GG and KG as release retarding materials in formulating controlled-release tablet dosage forms of 1.

  1. Nanocomposite/Hybrid Materials of Electroactive Polymers With Inorganic Oxides for Biosensor Applications

    National Research Council Canada - National Science Library

    Wei, Yen

    2001-01-01

    As proposed, we have successfully synthesized new electroactive and electronically conductive polyaniline polymethacrylate-silica nanocomposites and fabricated biosensor devices, aimed for detecting...

  2. Considerations for Contractile Electroactive Materials and Actuators

    Energy Technology Data Exchange (ETDEWEB)

    Lenore Rasmussen, David Schramm, Paul Rasmussen, Kevin Mullaly, Ras Labs, LLC, Intelligent Materials for Prosthetics & Automation, Lewis D. Meixler, Daniel Pearlman and Alice Kirk

    2011-05-23

    Ras Labs produces contractile electroactive polymer (EAP) based materials and actuators that bend, swell, ripple, and contract (new development) with low electric input. In addition, Ras Labs produces EAP materials that quickly contract and expand, repeatedly, by reversing the polarity of the electric input, which can be cycled. This phenomenon was explored using molecular modeling, followed by experimentation. Applied voltage step functions were also investigated. High voltage steps followed by low voltage steps produced a larger contraction followed by a smaller contraction. Actuator control by simply adjusting the electric input is extremely useful for biomimetic applications. Muscles are able to partially contract. If muscles could only completely contract, nobody could hold an egg, for example, without breaking it. A combination of high and low voltage step functions could produce gross motor function and fine manipulation within the same actuator unit. Plasma treated electrodes with various geometries were investigated as a means of providing for more durable actuation.

  3. Workload Control with Continuous Release

    NARCIS (Netherlands)

    Phan, B. S. Nguyen; Land, M. J.; Gaalman, G. J. C.

    2009-01-01

    Workload Control (WLC) is a production planning and control concept which is suitable for the needs of make-to-order job shops. Release decisions based on the workload norms form the core of the concept. This paper develops continuous time WLC release variants and investigates their due date

  4. Controlled Release from Recombinant Polymers

    Science.gov (United States)

    Price, Robert; Poursaid, Azadeh; Ghandehari, Hamidreza

    2014-01-01

    Recombinant polymers provide a high degree of molecular definition for correlating structure with function in controlled release. The wide array of amino acids available as building blocks for these materials lend many advantages including biorecognition, biodegradability, potential biocompatibility, and control over mechanical properties among other attributes. Genetic engineering and DNA manipulation techniques enable the optimization of structure for precise control over spatial and temporal release. Unlike the majority of chemical synthetic strategies used, recombinant DNA technology has allowed for the production of monodisperse polymers with specifically defined sequences. Several classes of recombinant polymers have been used for controlled drug delivery. These include, but are not limited to, elastin-like, silk-like, and silk-elastinlike proteins, as well as emerging cationic polymers for gene delivery. In this article, progress and prospects of recombinant polymers used in controlled release will be reviewed. PMID:24956486

  5. Synthesis of a novel biodegradable and electroactive polyphosphazene for biomedical application

    International Nuclear Information System (INIS)

    Zhang Qingsong; Yan Yuhua; Li Shipu; Feng Tao

    2009-01-01

    To prepare one electroactive and biodegradable biomaterial for biomedical application, a new synthetic strategy was developed to synthesize a novel electrically conductive biodegradable polyphosphazene polymer containing parent aniline pentamer (PAP) and glycine ethyl ester (GEE) as side chains by a nucleophilic substitution reaction. The electrical conductivity of the polymer is ∼2 x 10 -5 S cm -1 in the semiconducting region upon preliminarily protonic-doped experiment. The degradation and RSC96 Schwann cells experiments in vitro prove that the polymer is biodegradable and beneficial to the cell adhesion and proliferation. The as-synthesized polymer also shows good solubility in common organic solvent and good film-forming properties. This new type of polymer has potential applications as scaffolds for neuronal and cardiovascular tissue engineering or other biomedical devices that require electroactivity.

  6. Silica nanoparticles for the layer-by-layer assembly of fully electro-active cytochrome c multilayers

    Directory of Open Access Journals (Sweden)

    Feifel Sven C

    2011-12-01

    influence of particle size are discussed. Conclusions This study demonstrates the ability to construct fully electro-active cyt c multilayer assemblies by using carboxy-modified silica nanoparticles. Thus it can be shown that functional, artificial systems can be build up following natural examples of protein arrangements. The absence of any conductive properties in the second building block clearly demonstrates that mechanisms for electron transfer through such protein multilayer assemblies is based on interprotein electron exchange, rather than on wiring of the protein to the electrode. The construction strategy of this multilayer system provides a new controllable route to immobilize proteins in multiple layers featuring direct electrochemistry without mediating shuttle molecules and controlling the electro-active amount by the number of deposition steps.

  7. Controlled drug release for tissue engineering.

    Science.gov (United States)

    Rambhia, Kunal J; Ma, Peter X

    2015-12-10

    Tissue engineering is often referred to as a three-pronged discipline, with each prong corresponding to 1) a 3D material matrix (scaffold), 2) drugs that act on molecular signaling, and 3) regenerative living cells. Herein we focus on reviewing advances in controlled release of drugs from tissue engineering platforms. This review addresses advances in hydrogels and porous scaffolds that are synthesized from natural materials and synthetic polymers for the purposes of controlled release in tissue engineering. We pay special attention to efforts to reduce the burst release effect and to provide sustained and long-term release. Finally, novel approaches to controlled release are described, including devices that allow for pulsatile and sequential delivery. In addition to recent advances, limitations of current approaches and areas of further research are discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Dielectric electroactive polymers comprising an ionic supramolecular structure

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to an ionic interpenetrating polymer network comprising at least one elastomer and an ionic supramolecular structure comprising the reaction product of at least two chemical compounds wherein each of said compounds has at least two functional groups and wherein said ...... compounds are able to undergo Lewis acid-base reactions. The interpenetrating polymer network may be used as dielectric electroactive polymers (DEAPs) having a high dielectric permittivity....

  9. Local control of striatal dopamine release

    Directory of Open Access Journals (Sweden)

    Roger eCachope

    2014-05-01

    Full Text Available The mesolimbic and nigrostriatal dopamine (DA systems play a key role in the physiology of reward seeking, motivation and motor control. Importantly, they are also involved in the pathophysiology of Parkinson’s and Huntington’s disease, schizophrenia and addiction. Control of DA release in the striatum is tightly linked to firing of DA neurons in the ventral tegmental area (VTA and the substantia nigra (SN. However, local influences in the striatum affect release by exerting their action directly on axon terminals. For example, endogenous glutamatergic and cholinergic activity is sufficient to trigger striatal DA release independently of cell body firing. Recent developments involving genetic manipulation, pharmacological selectivity or selective stimulation have allowed for better characterization of these phenomena. Such termino-terminal forms of control of DA release transform considerably our understanding of the mesolimbic and nigrostriatal systems, and have strong implications as potential mechanisms to modify impaired control of DA release in the diseased brain. Here, we review these and related mechanisms and their implications in the physiology of ascending DA systems.

  10. Long-Term Performance of Primary and Secondary Electroactive Biofilms Using Layered Corrugated Carbon Electrodes

    International Nuclear Information System (INIS)

    Baudler, André; Riedl, Sebastian; Schröder, Uwe

    2014-01-01

    The performance of primary and secondary electroactive biofilms grown on layered corrugated carbon (LCC) electrodes was studied over a period of several months. With an average projected current density of 6.7 mA cm −2 , the studied secondary electroactive biofilms outperformed the primary biofilms (3.0 mA cm −2 ) over the entire experimental period. At the same time, both, primary and secondary biofilms, exhibited a constant Coulomb efficiency of about 89%. The study further illustrates that three-dimensional electrodes such as LCC allow a sustained long-term performance without significant decrease in electrode performance.

  11. Long-Term Performance of Primary and Secondary Electroactive Biofilms Using Layered Corrugated Carbon Electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Baudler, André; Riedl, Sebastian; Schröder, Uwe, E-mail: uwe.schroeder@tu-bs.de [Institute of Environmental and Sustainable Chemistry, Technische Universität Braunschweig, Braunschweig (Germany)

    2014-07-30

    The performance of primary and secondary electroactive biofilms grown on layered corrugated carbon (LCC) electrodes was studied over a period of several months. With an average projected current density of 6.7 mA cm{sup −2}, the studied secondary electroactive biofilms outperformed the primary biofilms (3.0 mA cm{sup −2}) over the entire experimental period. At the same time, both, primary and secondary biofilms, exhibited a constant Coulomb efficiency of about 89%. The study further illustrates that three-dimensional electrodes such as LCC allow a sustained long-term performance without significant decrease in electrode performance.

  12. Advanced Electroactive Single Crystal and Polymer Actuator Concepts for Passive Optics, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes large stroke and high precision piezoelectric single crystal and electroactive polymer actuator concepts?HYBrid Actuation System (HYBAS)...

  13. Method of Making an Electroactive Sensing/Actuating Material for Carbon Nanotube Polymer Composite

    Science.gov (United States)

    Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

    2009-01-01

    An electroactive sensing or actuating material comprises a composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation of the composite when such composite is affected by an external stimulus. In another embodiment, the composite comprises a, third component of micro -sized to nano-sized particles of an electroactive ceramic that is also incorporated in the polymer matrix. The method for making the three-phase composite comprises either incorporating the carbon nanotubes in the polymer matrix before incorporation of the particles of ceramic or mixing the carbon nanotubes and particles of ceramic together in a solution before incorporation in the polymer matrix.

  14. Electroactive polymer gels based on epoxy resin

    Science.gov (United States)

    Samui, A. B.; Jayakumar, S.; Jayalakshmi, C. G.; Pandey, K.; Sivaraman, P.

    2007-04-01

    Five types of epoxy gels have been synthesized from common epoxy resins and hardeners. Fumed silica and nanoclay, respectively, were used as fillers and butyl methacrylate/acrylamide were used as monomer(s) for making interpenetrating polymer networks (IPNs) in three compositions. Swelling study, tensile property evaluation, dynamic mechanical thermal analysis, thermo-gravimetric analysis, scanning electron microscopy and electroactive property evaluation were done. The gels have sufficient mechanical strength and the time taken for bending to 20° was found to be 22 min for forward bias whereas it was just 12 min for reverse bias.

  15. Stimuli responsive nanomaterials for controlled release applications

    KAUST Repository

    Li, Song

    2012-01-01

    The controlled release of therapeutics has been one of the major challenges for scientists and engineers during the past three decades. Coupled with excellent biocompatibility profiles, various nanomaterials have showed great promise for biomedical applications. Stimuli-responsive nanomaterials guarantee the controlled release of cargo to a given location, at a specific time, and with an accurate amount. In this review, we have combined the major stimuli that are currently used to achieve the ultimate goal of controlled and targeted release by "smart" nanomaterials. The most heavily explored strategies include (1) pH, (2) enzymes, (3) redox, (4) magnetic, and (5) light-triggered release.

  16. Molecular architecture of electroactive and biodegradable copolymers composed of polylactide and carboxyl-capped aniline trimer.

    Science.gov (United States)

    Guo, Baolin; Finne-Wistrand, Anna; Albertsson, Ann-Christine

    2010-04-12

    Two-, four-, and six-armed branched copolymers with electroactive and biodegradable properties were synthesized by coupling reactions between poly(l-lactides) (PLLAs) with different architecture and carboxyl-capped aniline trimer (CCAT). The aniline oligomer CCAT was prepared from amino-capped aniline trimer and succinic anhydride. FT-IR, NMR, and SEC analyses confirmed the structure of the branched copolymers. UV-vis spectra and cyclic voltammetry of CCAT and copolymer solution showed good electroactive properties, similar to those of polyaniline. The water contact angle of the PLLAs was the highest, followed by the undoped copolymer and the doped copolymers. The values of doped four-armed copolymers were 54-63 degrees . Thermal properties of the polymers were studied by DSC and TGA. The copolymers had better thermal stability than the pure PLLAs, and the T(g) between 48-58 degrees C and T(m) between 146-177 degrees C of the copolymers were lower than those of the pure PLLA counterparts. This kind of electroactive and biodegradable copolymer has a great potential for applications in cardiovascular or neuronal tissue engineering.

  17. Electroactive polymers for sensing

    Science.gov (United States)

    2016-01-01

    Electromechanical coupling in electroactive polymers (EAPs) has been widely applied for actuation and is also being increasingly investigated for sensing chemical and mechanical stimuli. EAPs are a unique class of materials, with low-moduli high-strain capabilities and the ability to conform to surfaces of different shapes. These features make them attractive for applications such as wearable sensors and interfacing with soft tissues. Here, we review the major types of EAPs and their sensing mechanisms. These are divided into two classes depending on the main type of charge carrier: ionic EAPs (such as conducting polymers and ionic polymer–metal composites) and electronic EAPs (such as dielectric elastomers, liquid-crystal polymers and piezoelectric polymers). This review is intended to serve as an introduction to the mechanisms of these materials and as a first step in material selection for both researchers and designers of flexible/bendable devices, biocompatible sensors or even robotic tactile sensing units. PMID:27499846

  18. Micro-pseudocapacitors with Electroactive Polymer Electrodes: Towards Ac-Line Filtering Applications

    KAUST Repository

    Kurra, Narendra

    2016-05-05

    In this study, we investigate the frequency response of microsupercapacitors based on pseudocapacitive conducting polymer electrodes such as poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole (PPY) and polyaniline (PANI). It is shown that by proper choice of polymeric material and device structure, mainiturized microsupercapacitors based on electroactive polymers can match the frequency response of commercial bulky electrolytic capacitors. Specifically, we shsow that PEDOT-based microsupercapacitors exhibit phase angle of -80.5º at 120 Hz which is comparable to commercial bulky electrolytic capacitors, but with an order of magnitude higher capacitance density (3 FV/cm3). The trade-off between the areal capacitance (CA) and frequency response in the 2D architecture (CA = 0.3 mF/cm2, phase angle of -80.5º at 120 Hz) is improved by designing 3D thin film architecture (CA = 3 mF/cm2, phase angle of -60º at 120 Hz). Our work demonstrates that fast frequency response can be achieved using electroactive polymer electrodes.

  19. Micro-pseudocapacitors with Electroactive Polymer Electrodes: Towards Ac-Line Filtering Applications

    KAUST Repository

    Kurra, Narendra; Jiang, Qiu; Syed, Ahad; Xia, Chuan; Alshareef, Husam N.

    2016-01-01

    In this study, we investigate the frequency response of microsupercapacitors based on pseudocapacitive conducting polymer electrodes such as poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole (PPY) and polyaniline (PANI). It is shown that by proper choice of polymeric material and device structure, mainiturized microsupercapacitors based on electroactive polymers can match the frequency response of commercial bulky electrolytic capacitors. Specifically, we shsow that PEDOT-based microsupercapacitors exhibit phase angle of -80.5º at 120 Hz which is comparable to commercial bulky electrolytic capacitors, but with an order of magnitude higher capacitance density (3 FV/cm3). The trade-off between the areal capacitance (CA) and frequency response in the 2D architecture (CA = 0.3 mF/cm2, phase angle of -80.5º at 120 Hz) is improved by designing 3D thin film architecture (CA = 3 mF/cm2, phase angle of -60º at 120 Hz). Our work demonstrates that fast frequency response can be achieved using electroactive polymer electrodes.

  20. Encapsulation of ionic electroactive polymers: reducing the interaction with environment

    Science.gov (United States)

    Jaakson, P.; Aabloo, A.; Tamm, T.

    2016-04-01

    Ionic electro-active polymer (iEAP) actuators are composite materials that change their mechanical properties in response to external electrical stimulus. The interest in these devices is mainly driven by their capability to generate biomimetic movements, and their potential use in soft robotics. The driving voltage of an iEAP-actuator (0.5… 3 V) is at least an order of magnitude lower than that needed for other types of electroactive polymers. To apply iEAP-actuators in potential real-world applications, the capability of operating in different environments (open air, different solvents) must be available. In their natural form, the iEAP-actuators are capable of interacting with the surrounding environment (evaporation of solvent from the electrolyte solution, ion or solvent exchange, humidity effects), therefore, for prevention of unpredictable behavior of the actuator and the contamination of the environment, encapsulation of the actuator is needed. The environmental contamination aspect of the encapsulation material is substantial when selecting an applicable encapsulant. The suitable encapsulant should form thin films, be light in weight, elastic, fit tightly, low cost, and easily reproducible. The main goal of the present study is to identify and evaluate the best potential encapsulation techniques for iEAPactuators. Various techniques like thin film on liquid coating, dip coating, hot pressing, hot rolling; and several materials like polydimethylsiloxane, polyurethane, nitrocellulose, paraffin-composite-films were investigated. The advantages and disadvantages of the combinations of the above mentioned techniques and materials are discussed. Successfully encapsulated iEAP-actuators gained durability and were stably operable for long periods of time under ambient conditions. The encapsulation process also increased the stability of the iEAP-actuator by minimizing the environment effects. This makes controlling iEAP-actuators more straight-forward and

  1. Electroactive polymer actuators as artificial muscles: are they ready for bioinspired applications?

    DEFF Research Database (Denmark)

    Carpi, Federico; Kornbluh, Roy; Sommer-Larsen, Peter

    2011-01-01

    Electroactive polymer (EAP) actuators are electrically responsive materials that have several characteristics in common with natural muscles. Thus, they are being studied as 'artificial muscles' for a variety of biomimetic motion applications. EAP materials are commonly classified into two major...

  2. Dual-controlled release system of drugs for bone regeneration.

    Science.gov (United States)

    Kim, Yang-Hee; Tabata, Yasuhiko

    2015-11-01

    Controlled release systems have been noted to allow drugs to enhance their ability for bone regeneration. To this end, various biomaterials have been used as the release carriers of drugs, such as low-molecular-weight drugs, growth factors, and others. The drugs are released from the release carriers in a controlled fashion to maintain their actions for a long time period. Most research has been focused on the controlled release of single drugs to demonstrate the therapeutic feasibility. Controlled release of two combined drugs, so-called dual release systems, are promising and important for tissue regeneration. This is because the tissue regeneration process of bone formation is generally achieved by multiple bioactive molecules, which are produced from cells by other molecules. If two types of bioactive molecules, (i.e., drugs), are supplied in an appropriate fashion, the regeneration process of living bodies will be efficiently promoted. This review focuses on the bone regeneration induced by dual-controlled release of drugs. In this paper, various dual-controlled release systems of drugs aiming at bone regeneration are overviewed explaining the type of drugs and their release materials. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Microbial fuel cell based on electroactive sulfate-reducing biofilm

    International Nuclear Information System (INIS)

    Angelov, Anatoliy; Bratkova, Svetlana; Loukanov, Alexandre

    2013-01-01

    Highlights: ► Regulation and management of electricity generation by variation of residence time. ► Design of microbial fuel cell based on electroactive biofilm on zeolite. ► Engineering solution for removing of the obtained elemental sulfur. - abstract: A two chambered laboratory scale microbial fuel cell (MFC) has been developed, based on natural sulfate-reducing bacterium consortium in electroactive biofilm on zeolite. The MFC utilizes potassium ferricyanide in the cathode chamber as an electron acceptor that derives electrons from the obtained in anode chamber H 2 S. The molecular oxygen is finally used as a terminal electron acceptor at cathode compartment. The generated power density was 0.68 W m −2 with current density of 3.2 A m −2 at 150 Ω electrode resistivity. The hydrogen sulfide itself is produced by microbial dissimilative sulfate reduction process by utilizing various organic substrates. Finally, elemental sulfur was identified as the predominant final oxidation product in the anode chamber. It was removed from MFC through medium circulation and gathering in an external tank. This report reveals dependence relationship between the progress of general electrochemical parameters and bacterial sulfate-reduction rate. The presented MFC design can be used for simultaneous sulfate purification of mining drainage wastewater and generation of renewable electricity

  4. How controlled release technology can aid gene delivery.

    Science.gov (United States)

    Jo, Jun-Ichiro; Tabata, Yasuhiko

    2015-01-01

    Many types of gene delivery systems have been developed to enhance the level of gene expression. Controlled release technology is a feasible gene delivery system which enables genes to extend the expression duration by maintaining and releasing them at the injection site in a controlled manner. This technology can reduce the adverse effects by the bolus dose administration and avoid the repeated administration. Biodegradable biomaterials are useful as materials for the controlled release-based gene delivery technology and various biodegradable biomaterials have been developed. Controlled release-based gene delivery plays a critical role in a conventional gene therapy and genetic engineering. In the gene therapy, the therapeutic gene is released from biodegradable biomaterial matrices around the tissue to be treated. On the other hand, the intracellular controlled release of gene from the sub-micro-sized matrices is required for genetic engineering. Genetic engineering is feasible for cell transplantation as well as research of stem cells biology and medicine. DNA hydrogel containing a sequence of therapeutic gene and the exosome including the individual specific nucleic acids may become candidates for controlled release carriers. Technologies to deliver genes to cell aggregates will play an important role in the promotion of regenerative research and therapy.

  5. Ionic electroactive polymer artificial muscles in space applications.

    Science.gov (United States)

    Punning, Andres; Kim, Kwang J; Palmre, Viljar; Vidal, Frédéric; Plesse, Cédric; Festin, Nicolas; Maziz, Ali; Asaka, Kinji; Sugino, Takushi; Alici, Gursel; Spinks, Geoff; Wallace, Gordon; Must, Indrek; Põldsalu, Inga; Vunder, Veiko; Temmer, Rauno; Kruusamäe, Karl; Torop, Janno; Kaasik, Friedrich; Rinne, Pille; Johanson, Urmas; Peikolainen, Anna-Liisa; Tamm, Tarmo; Aabloo, Alvo

    2014-11-05

    A large-scale effort was carried out to test the performance of seven types of ionic electroactive polymer (IEAP) actuators in space-hazardous environmental factors in laboratory conditions. The results substantiate that the IEAP materials are tolerant to long-term freezing and vacuum environments as well as ionizing Gamma-, X-ray, and UV radiation at the levels corresponding to low Earth orbit (LEO) conditions. The main aim of this material behaviour investigation is to understand and predict device service time for prolonged exposure to space environment.

  6. Effect of carbon nanofillers on the microstructure and electromechanical properties of electroactive polymers

    Science.gov (United States)

    Sigamani, Nirmal Shankar

    electroactive polymers, the relatively high electrical conductivity and low breakdown limits their use for practical applications. So next step was to exploit the advantages of a conductive carbon nanostructure while controlling its network to better impact its electrical properties which could also lead to higher breakdown strength. Based on the promising impact of hybrid nanofillers on the ferroelectric polymer PVDF, a similar polymer with a relaxor ferroelectric character is considered owing to its higher inherent electroactive response and higher breakdown strength. Given that it is not broadly studied, there was a need to understand structure-property relationship of the PVDF TrFE CTFE terpolymer. Hence, the effect of processing conditions (such as annealing times and isothermal crystallization temperatures) on the microstructure and the subsequent electromechanical properties were analyzed. This structure-property analysis helped to understand the relation between the different types of crystalline phases and the degrees of crystallinity as well as to observe crystal sizes as they relate to the electric field induced strain. As a final step, the effect of the hybrid SWNT/GO on both microstructure and electromechanical properties of the terpolymer were studied. The hybrid nanofillers were chemically modified to form a covalent bond between them to improve their interaction. The morphology of the hybrid nanofillers after the chemical modification was studied for two different chemical modification routes: one using thionyl chloride, other using NHS and EDAC as catalysts. Of the two methods, the NHS and EDAC catalyst method showed a strong uniform interaction, confirmed by SEM images and FTIR results, with a shift in the peak to 1630 cm-1. Finally, the effect of hybrid SWNT and GO on the electromechanical properties were studied and, interestingly, the hybrid terpolymer nanocomposite film showed a lower electroactive strain compared to pure terpolymer at the same applied

  7. 28 CFR 541.50 - Release from a control unit.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Release from a control unit. 541.50... INMATE DISCIPLINE AND SPECIAL HOUSING UNITS Control Unit Programs § 541.50 Release from a control unit. (a) Only the Executive Panel may release an inmate from a control unit. The following factors are...

  8. EPICS application source/release control

    International Nuclear Information System (INIS)

    Zieman, B.; Anderson, J.; Kraimer, M.

    1995-01-01

    This manual describes a set of Application Source/Release Control tools (appSR) that can be used to develop software for EPICS based control systems. The Application Source/Release Control System (appSR) has been unbundled from base EPICS and is now available as an EPICS extension. Due to this unbundling, two new directories must be added to a user's path (see section ''Environment'' on page 3 for more information) and a new command getapp must be issued after the getrel command to get a specific version of appSR (see section ''Creating The Initial Application System Area'' on page 7 for more information). It is now required that GNU make version 3.71 or later be used for makes instead of SUN make. Users should now type gmake instead of make

  9. Overview study of LNG release prevention and control systems

    Energy Technology Data Exchange (ETDEWEB)

    Pelto, P.J.; Baker, E.G.; Holter, G.M.; Powers, T.B.

    1982-03-01

    The liquefied natural gas (LNG) industry employs a variety of release prevention and control techniques to reduce the likelihood and the consequences of accidental LNG releases. A study of the effectiveness of these release prevention and control systems is being performed. Reference descriptions for the basic types of LNG facilities were developed. Then an overview study was performed to identify areas that merit subsequent and more detailed analyses. The specific objectives were to characterize the LNG facilities of interest and their release prevention and control systems, identify possible weak links and research needs, and provide an analytical framework for subsequent detailed analyses. The LNG facilities analyzed include a reference export terminal, marine vessel, import terminal, peakshaving facility, truck tanker, and satellite facility. A reference description for these facilities, a preliminary hazards analysis (PHA), and a list of representative release scenarios are included. The reference facility descriptions outline basic process flows, plant layouts, and safety features. The PHA identifies the important release prevention operations. Representative release scenarios provide a format for discussing potential initiating events, effects of the release prevention and control systems, information needs, and potential design changes. These scenarios range from relatively frequent but low consequence releases to unlikely but large releases and are the principal basis for the next stage of analysis.

  10. The electrochemical signature of functionalized single-walled carbon nanotubes bearing electroactive groups

    International Nuclear Information System (INIS)

    Le Floch, Fabien; Thuaire, Aurelie; Simonato, Jean-Pierre; Bidan, Gerard

    2009-01-01

    We report the modification and characterization of single-walled carbon nanotubes (SWCNTs) in view of molecular sensing applications. We found that ultrasonicated SWCNTs present sticking properties that make them adhere on electrode surfaces. This allows excellent characterization of SWCNTs by cyclic voltammetry (CV) before and after chemical functionalization with diazonium salts bearing electroactive groups. Bare SWCNTs presented distinct invariant shapes in CV, used as control curves, in comparison with functionalized SWCNTs for which specific signatures corresponding to the presence of grafted molecules were identified. According to the electronic substituents in the para position of the diazonium salts, divergent behaviours were observed for the grafting reactions. Diazonium salts having electrowithdrawing groups could be grafted without electrochemical induction whereas those bearing electron donating groups required a cathodic potential to generate the formation of the radical species.

  11. The electrochemical signature of functionalized single-walled carbon nanotubes bearing electroactive groups

    Energy Technology Data Exchange (ETDEWEB)

    Le Floch, Fabien; Thuaire, Aurelie; Simonato, Jean-Pierre [LITEN/DTNM/LCRE, CEA-Grenoble 17 rue des Martyrs, 38054 Grenoble cedex 9 (France); Bidan, Gerard [INAC/DIR, CEA-Grenoble 17 rue des Martyrs, 38054 Grenoble cedex 9 (France)], E-mail: jean-pierre.simonato@cea.fr

    2009-04-08

    We report the modification and characterization of single-walled carbon nanotubes (SWCNTs) in view of molecular sensing applications. We found that ultrasonicated SWCNTs present sticking properties that make them adhere on electrode surfaces. This allows excellent characterization of SWCNTs by cyclic voltammetry (CV) before and after chemical functionalization with diazonium salts bearing electroactive groups. Bare SWCNTs presented distinct invariant shapes in CV, used as control curves, in comparison with functionalized SWCNTs for which specific signatures corresponding to the presence of grafted molecules were identified. According to the electronic substituents in the para position of the diazonium salts, divergent behaviours were observed for the grafting reactions. Diazonium salts having electrowithdrawing groups could be grafted without electrochemical induction whereas those bearing electron donating groups required a cathodic potential to generate the formation of the radical species.

  12. Electroactive polyurethane/siloxane derived from castor oil as a versatile cardiac patch, part I: Synthesis, characterization, and myoblast proliferation and differentiation.

    Science.gov (United States)

    Baheiraei, Nafiseh; Gharibi, Reza; Yeganeh, Hamid; Miragoli, Michele; Salvarani, Nicolò; Di Pasquale, Elisa; Condorelli, Gianluigi

    2016-03-01

    Tissue-engineered cardiac patch aims at regenerating an infarcted heart by improving cardiac function and providing mechanical support to the diseased myocardium. In order to take advantages of electroactivity, a new synthetic method was developed for the introduction of an electroactive oligoaniline into the backbone of prepared patches. For this purpose, a series of electroactive polyurethane/siloxane films containing aniline tetramer (AT) was prepared through sol-gel reaction of trimethoxysilane functional intermediate polyurethane prepolymers made from castor oil and poly(ethylene glycol). Physicochemical, mechanical, and electrical conductivity of samples were evaluated and the recorded results were correlated to their structural characteristics. The optimized films were proved to be biodegradable and have tensile properties suitable for cardiac patch application. The embedded AT moieties in the backbone of the prepared samples preserved their electroactivity with the electrical conductivity in the range of 10 -4 S/cm. The prepared films were compatible with proliferation of C2C12 and had potential for enhancing myotube formation even without external electrical stimulation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 775-787, 2016. © 2015 Wiley Periodicals, Inc.

  13. Stimuli-Responsive Materials for Controlled Release Applications

    KAUST Repository

    Li, Song

    2015-04-01

    The controlled release of therapeutics has been one of the major challenges for scientists and engineers during the past three decades. To address this outstanding problem, the design and fabrication of stimuli-responsive materials are pursued to guarantee the controlled release of cargo at a specific time and with an accurate amount. Upon applying different stimuli such as light, magnetic field, heat, pH change, enzymes or redox, functional materials change their physicochemical properties through physical transformation or chemical reactions, allowing the release of payload agents on demand. This dissertation studied three stimuli-responsive membrane systems for controlled release from films of macro sizes to microcapsules of nano sizes. The first membrane system is a polymeric composite film which can decrease and sustain diffusion upon light irradiation. The photo-response of membranes is based on the photoreaction of cinnamic derivatives. The second one is composite membrane which can improve diffusion upon heating. The thermo-response of membranes comes from the volume phase transition ability of hydrogels. The third one is microcapsule which can release encapsulated agents upon light irradiation. The photo-response of capsules results from the photoreaction of nitrobenzyl derivatives. The study on these membrane systems reveals that stimuli-responsive release can be achieved by utilizing different functional materials on either macro or micro level. Based on the abundant family of smart materials, designing and fabricating stimuli-responsive systems shall lead to various advanced release processes on demand for biomedical applications.

  14. Highly active bidirectional electron transfer by a self-assembled electroactive reduced-graphene-oxide-hybridized biofilm.

    Science.gov (United States)

    Yong, Yang-Chun; Yu, Yang-Yang; Zhang, Xinhai; Song, Hao

    2014-04-22

    Low extracellular electron transfer performance is often a bottleneck in developing high-performance bioelectrochemical systems. Herein, we show that the self-assembly of graphene oxide and Shewanella oneidensis MR-1 formed an electroactive, reduced-graphene-oxide-hybridized, three-dimensional macroporous biofilm, which enabled highly efficient bidirectional electron transfers between Shewanella and electrodes owing to high biomass incorporation and enhanced direct contact-based extracellular electron transfer. This 3D electroactive biofilm delivered a 25-fold increase in the outward current (oxidation current, electron flux from bacteria to electrodes) and 74-fold increase in the inward current (reduction current, electron flux from electrodes to bacteria) over that of the naturally occurring biofilms. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Thermal stress in flexible interdigital transducers with anisotropic electroactive cellulose substrates

    Science.gov (United States)

    Yoon, Sean J.; Kim, Jung Woong; Kim, Hyun Chan; Kang, Jinmo; Kim, Jaehwan

    2017-12-01

    Thermal stress in flexible interdigital transducers a reliability concern in the development of flexible devices, which may lead to interface delamination, stress voiding and plastic deformation. In this paper, a mathematical model is presented to investigate the effect of material selections on the thermal stress in interdigital transducers. We modified the linear relationships in the composite materials theory with the effect of high curvature, anisotropic substrate and small substrate thickness. We evaluated the thermal stresses of interdigital transducers, fabricated with various electrodes, insulators and substrate materials for the comparison. The results show that, among various insulators, organic polymer developed the highest stress level while oxide showed the lowest stress level. Aluminium shows a higher stress level and curvature as an electrode than gold. As substrate materials, polyimide and electroactive cellulose show similar stress levels except the opposite sign convention to each other. Polyimide shows positive curvatures while electroactive cellulose shows negative curvatures, which is attributed to the stress and thermal expansion state of the metal/insulator composite. The results show that the insulator is found to be responsible for the confinement across the metal lines while the substrate is responsible for the confinement along the metal lines.

  16. Controlled release studies of calcium alginate hydrogels

    International Nuclear Information System (INIS)

    Rendevski, S.; Andonovski, A.; Mahmudi, N.

    2012-01-01

    Controlled release of substances in many cases may be achieved from calcium alginate hydrogels. In this research, the time dependence of the mass of released model substance bovine serum albumin (BSA) from calcium alginate spherical hydrogels of three different types (G/M ratio) have been investigated. The hydrogels were prepared with the drop-wise method of sodium alginate aqueous solutions with concentration of 0.02 g/cm 3 with 0.01 g/cm 3 BSA and a gelling water bath of chitosan in 0.2 M CH 3 COOH/0.4 M CH 3 COONa with added 0.2 M CaCl 2 .The hydrogel structures were characterized by dynamic light scattering and scanning electron microscopy. The controlled release studies were conducted by UV-Vis spectrophotometry of the released medium with p H=7 at 37 °C. The results showed that the model of osmotic pumping is the dominant mechanism of the release. Also, large dependences of the release profile on the homogeneity of the hydrogels were found. (Author)

  17. Birth control - slow release methods

    Science.gov (United States)

    Contraception - slow-release hormonal methods; Progestin implants; Progestin injections; Skin patch; Vaginal ring ... might want to consider a different birth control method. SKIN PATCH The skin patch is placed on ...

  18. Synthesis, characterization and antioxidant activity of a novel electroactive and biodegradable polyurethane for cardiac tissue engineering application

    International Nuclear Information System (INIS)

    Baheiraei, Nafiseh; Yeganeh, Hamid; Ai, Jafar; Gharibi, Reza; Azami, Mahmoud; Faghihi, Faezeh

    2014-01-01

    There has been a growing trend towards applying conducting polymers for electrically excitable cells to increase electrical signal propagation within the cell-loaded substrates. A novel biodegradable electroactive polyurethane containing aniline pentamer (AP-PU) was synthesized and fully characterized by spectroscopic methods. To tune the physico-chemical properties and biocompatibility, the AP-PU was blended with polycaprolactone (PCL). The presence of electroactive moieties and the electroactivity behavior of the prepared films were confirmed by UV–visible spectroscopy and cyclic voltammetry. A conventional four probe analysis demonstrated the electrical conductivity of the films in the semiconductor range (∼ 10 −5 S/cm). MTT assays using L929 mouse fibroblast and human umbilical vein endothelial cells (HUVECs) showed that the prepared blend (PB) displayed more cytocompatibility compared with AP-PU due to the introduction of a biocompatible PCL moiety. The in vitro cell culture also confirmed that PB was as supportive as tissue culture plate. The antioxidant activity of the AP-PU was proved using 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay by employing UV–vis spectroscopy. In vitro degradation tests conducted in phosphate-buffered saline, pH 7.4 and pH 5.5, proved that the films were also biodegradable. The results of this study have highlighted the potential application of this bioelectroactive polyurethane as a platform substrate to study the effect of electrical signals on cell activities and to direct desirable cell function for tissue engineering applications. - Highlights: • Straight forward methodology for synthesis of electroactive polyurethane • Biodegradability and non-toxicity through proper selection of starting materials • Supporting cell proliferation and attachment combined with antioxidant property

  19. Synthesis, characterization and antioxidant activity of a novel electroactive and biodegradable polyurethane for cardiac tissue engineering application

    Energy Technology Data Exchange (ETDEWEB)

    Baheiraei, Nafiseh [Department of Tissue Engineering, School of Advanced Medical Technologies, Tehran University of Medical Sciences, 1417755469 Tehran (Iran, Islamic Republic of); Yeganeh, Hamid, E-mail: h.yeganeh@ippi.ac.ir [Department of Polyurethane, Iran Polymer and Petrochemical Institute, P.O. Box: 14965/115, Tehran (Iran, Islamic Republic of); Ai, Jafar [Department of Tissue Engineering, School of Advanced Medical Technologies, Tehran University of Medical Sciences, 1417755469 Tehran (Iran, Islamic Republic of); Brain and Spinal Injury Research Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Gharibi, Reza [Department of Polyurethane, Iran Polymer and Petrochemical Institute, P.O. Box: 14965/115, Tehran (Iran, Islamic Republic of); Azami, Mahmoud; Faghihi, Faezeh [Department of Tissue Engineering, School of Advanced Medical Technologies, Tehran University of Medical Sciences, 1417755469 Tehran (Iran, Islamic Republic of)

    2014-11-01

    There has been a growing trend towards applying conducting polymers for electrically excitable cells to increase electrical signal propagation within the cell-loaded substrates. A novel biodegradable electroactive polyurethane containing aniline pentamer (AP-PU) was synthesized and fully characterized by spectroscopic methods. To tune the physico-chemical properties and biocompatibility, the AP-PU was blended with polycaprolactone (PCL). The presence of electroactive moieties and the electroactivity behavior of the prepared films were confirmed by UV–visible spectroscopy and cyclic voltammetry. A conventional four probe analysis demonstrated the electrical conductivity of the films in the semiconductor range (∼ 10{sup −5} S/cm). MTT assays using L929 mouse fibroblast and human umbilical vein endothelial cells (HUVECs) showed that the prepared blend (PB) displayed more cytocompatibility compared with AP-PU due to the introduction of a biocompatible PCL moiety. The in vitro cell culture also confirmed that PB was as supportive as tissue culture plate. The antioxidant activity of the AP-PU was proved using 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay by employing UV–vis spectroscopy. In vitro degradation tests conducted in phosphate-buffered saline, pH 7.4 and pH 5.5, proved that the films were also biodegradable. The results of this study have highlighted the potential application of this bioelectroactive polyurethane as a platform substrate to study the effect of electrical signals on cell activities and to direct desirable cell function for tissue engineering applications. - Highlights: • Straight forward methodology for synthesis of electroactive polyurethane • Biodegradability and non-toxicity through proper selection of starting materials • Supporting cell proliferation and attachment combined with antioxidant property.

  20. Controlled release of tocopherols from polymer blend films

    Science.gov (United States)

    Obinata, Noe

    Controlled release packaging has great potential to increase storage stability of foods by releasing active compounds into foods continuously over time. However, a major limitation in development of this technology is the inability to control the release and provide rates useful for long term storage of foods. Better understanding of the factors affecting active compound release is needed to overcome this limitation. The objective of this research was to investigate the relationship between polymer composition, polymer processing method, polymer morphology, and release properties of active compounds, and to provide proof of principle that compound release is controlled by film morphology. A natural antioxidant, tocopherol was used as a model active compound because it is natural, effective, heat stable, and soluble in most packaging polymers. Polymer blend films were produced from combination of linear low density polyethylene (LLDPE) and high density polyethylene (HDPE), polypropylene (PP), or polystyrene (PS) with 3000 ppm mixed tocopherols using conventional blending method and innovative blending method, smart blending with a novel mixer using chaotic advection. Film morphologies were visualized with scanning electron microscopy (SEM). Release of tocopherols into 95% ethanol as a food simulant was measured by UV/Visible spectrophotometry or HPLC, and diffusivity of tocopherols in the polymers was estimated from this data. Polymer composition (blend proportions) and processing methods have major effects on film morphology. Four different types of morphologies, dispersed, co-continuous, fiber, and multilayer structures were developed by either conventional extrusion or smart blending. With smart blending of fixed polymer compositions, different morphologies were progressively developed with fixed polymer composition as the number of rod rotations increased, providing a way to separate effects of polymer composition and morphology. The different morphologies

  1. Model-based computer-aided design for controlled release of pesticides

    DEFF Research Database (Denmark)

    Muro Sunè, Nuria; Gani, Rafiqul; Bell, G.

    2005-01-01

    In the field of controlled release technology for pesticides or active ingredients (AI), models that can predict its delivery during application are important for purposes of design and marketing of the pesticide product. Appropriate models for the controlled release of pesticides, if available, ...... extended models have been developed and implemented into a computer-aided system. The total model consisting of the property models embedded into the release models are then employed to study the release of different combinations of AIs and polymer-based microcapsules.......In the field of controlled release technology for pesticides or active ingredients (AI), models that can predict its delivery during application are important for purposes of design and marketing of the pesticide product. Appropriate models for the controlled release of pesticides, if available...

  2. Biomimetic electroactive polyimide with rose petal-like surface structure for anticorrosive coating application

    Directory of Open Access Journals (Sweden)

    W. F. Ji

    2017-08-01

    Full Text Available In this work, an electroactive polyimide (EPI coating with biomimetic surface structure of rose petal used in anticorrosion application was first presented. First of all, amino-capped aniline trimer (ACAT was synthesized by oxidative coupling reaction, followed by characterized through Fourier transform infrared spectroscooy (FTIR, liquid chromatography – mass spcerometry (LC-MS and proton nuclear magnetic resonance (1H-NMR spectroscopy. Subsequently, as-prepared ACAT was reacted with isopropylidenediphenoxy-bis(phthalic anhydride (BPADA to give electroactive poly(amic acid (EPAA. Moreover, poly(dimethylsiloxane (PDMS was used to be the soft negative template for pattern transfer from the surface of rose petal to the surface of polymer coating. The EPI coating with biomimetic structure was obtained by programmed heating the EPAA slurry casting onto the negative PDMS template. The anticorrosive performance of as-prepared biomimetic EPI coating was demonstrated by performing a series of electrochemical measurements (Tafel, Nyquist, and Bode plots upon cold-rolled steel (CRS electrode in a NaCl aqueous solution. It should be noted that the biomimetic EPI coating with rose petal-like structure was found to exhibit better anticorrosion than that of EPI without biomimetic structure. Moreover, the surface contact angle of water droplets for biomimetic EPI coating was found to be ~150°, which is significantly higher than that of EPI coating with smooth structure (~87°, indicating that the EPI coating with biomimetic structure reveals better hydrophobicity. The apparent mechanism for improved anticorrosive properties is twofold: (1 the biomimetic structure of EPI coating can repel water droplets. (2 electroactivity of EPI coating promotes the formation of densely passive layer of metal oxide on metallic surface.

  3. Electroactive β-crystalline phase inclusion and photoluminescence response of a heat-controlled spin-coated PVDF/TiO2 free-standing nanocomposite film for a nanogenerator and an active nanosensor

    Science.gov (United States)

    Mehebub Alam, Md; Sultana, Ayesha; Sarkar, Debabrata; Mandal, Dipankar

    2017-09-01

    The electroactive β-phase is most desirable due to its highest piezo-, pyro- and ferroelectric properties in poly(vinylidene fluoride) (PVDF). Induction of the β-phase is successfully accomplished in titanium dioxide (TiO2) nanoparticles (NPs) doped spin-coated PVDF nanocomposite (PNC) films. The optimized yields of β-phase and homogeneous ultra-smooth free-standing PNC film is utilized in a mechanical-energy harvesting application by fabricating a nanogenerator (NG) where the typical electrical poling step is not undertaken. Under a repeated human finger touch and release process, it delivers an open-circuit voltage of 5 V. Moreover, the physical sensing capabilities of the NG are examined through harvesting mechanical energy from mouse clicking of a laptop and wrist pulse detection, which indicates that it can also be used as a nanosensor. The blue photoluminescence centred at 444 nm, which was also observed in PNC films, makes us anticipate a new type of photonic application where the design feasibility of hybrid sensors, i.e. electromechanical and photonic combination, is also possible.

  4. Photoresponsive lipid-polymer hybrid nanoparticles for controlled doxorubicin release

    Science.gov (United States)

    Yao, Cuiping; Wu, Ming; Zhang, Cecheng; Lin, Xinyi; Wei, Zuwu; Zheng, Youshi; Zhang, Da; Zhang, Zhenxi; Liu, Xiaolong

    2017-06-01

    Currently, photoresponsive nanomaterials are particularly attractive due to their spatial and temporal controlled drug release abilities. In this work, we report a photoresponsive lipid-polymer hybrid nanoparticle for remote controlled delivery of anticancer drugs. This hybrid nanoparticle comprises three distinct functional components: (i) a poly(D,L-lactide-co-glycolide) (PLGA) core to encapsulate doxorubicin; (ii) a soybean lecithin monolayer at the interface of the core and shell to act as a molecular fence to prevent drug leakage; (iii) a photoresponsive polymeric shell with anti-biofouling properties to enhance nanoparticle stability, which could be detached from the nanoparticle to trigger the drug release via a decrease in the nanoparticle’s stability under light irradiation. In vitro results revealed that this core-shell nanoparticle had excellent light-controlled drug release behavior (76% release with light irradiation versus 10% release without light irradiation). The confocal microscopy and flow cytometry results also further demonstrated the light-controlled drug release behavior inside the cancer cells. Furthermore, a CCK8 assay demonstrated that light irradiation could significantly improve the efficiency of killing cancer cells. Meanwhile, whole-animal fluorescence imaging of a tumor-bearing mouse also confirmed that light irradiation could trigger drug release in vivo. Taken together, our data suggested that a hybrid nanoparticle could be a novel light controlled drug delivery system for cancer therapy.

  5. On the impact of self-clearing on electroactive polymer (EAP) actuators

    Science.gov (United States)

    Ahmed, Saad; Ounaies, Zoubeida; Lanagan, Michael T.

    2017-10-01

    Electroactive polymer (EAP)-based actuators have large potential for a wide array of applications; however, their practical implementation is still a challenge because of the requirement of high driving voltage, which most often leads to premature defect-driven electrical breakdown. Polymer-based capacitors have the ability to clear defects with partial electrical breakdown and subsequent removal of a localized electrode section near the defect. In this study, this process, which is known as self-clearing, is adopted for EAP technologies. We report a methodical approach to self-clear an EAP, more specifically P(VDF-TrFE-CTFE) terpolymer, to delay premature defect-driven electrical breakdown of the terpolymer actuators at high operating electric fields. Breakdown results show that electrical breakdown strength is improved up to 18% in comparison to a control sample after self-clearing. Furthermore, the electromechanical performance in terms of blocked force and free displacement of P(VDF-TrFE-CTFE) terpolymer-based bending actuators are examined after self-clearing and precleared samples show improved blocked force, free displacement and maximum sustainable electric field compared to control samples. The study demonstrates that controlled self-clearing of EAPs improves the breakdown limit and reliability of the EAP actuators for practical applications without impeding their electromechanical performance.

  6. Thick electrodes including nanoparticles having electroactive materials and methods of making same

    Science.gov (United States)

    Xiao, Jie; Lu, Dongping; Liu, Jun; Zhang, Jiguang; Graff, Gordon L.

    2017-02-21

    Electrodes having nanostructure and/or utilizing nanoparticles of active materials and having high mass loadings of the active materials can be made to be physically robust and free of cracks and pinholes. The electrodes include nanoparticles having electroactive material, which nanoparticles are aggregated with carbon into larger secondary particles. The secondary particles can be bound with a binder to form the electrode.

  7. Haptic interfaces using dielectric electroactive polymers

    Science.gov (United States)

    Ozsecen, Muzaffer Y.; Sivak, Mark; Mavroidis, Constantinos

    2010-04-01

    Quality, amplitude and frequency of the interaction forces between a human and an actuator are essential traits for haptic applications. A variety of Electro-Active Polymer (EAP) based actuators can provide these characteristics simultaneously with quiet operation, low weight, high power density and fast response. This paper demonstrates a rolled Dielectric Elastomer Actuator (DEA) being used as a telepresence device in a heart beat measurement application. In the this testing, heart signals were acquired from a remote location using a wireless heart rate sensor, sent through a network and DEA was used to haptically reproduce the heart beats at the medical expert's location. A series of preliminary human subject tests were conducted that demonstrated that a) DE based haptic feeling can be used in heart beat measurement tests and b) through subjective testing the stiffness and actuator properties of the EAP can be tuned for a variety of applications.

  8. MWCNTs-reinforced epoxidized linseed oil plasticized polylactic acid nanocomposite and its electroactive shape memory behaviour.

    Science.gov (United States)

    Alam, Javed; Alam, Manawwer; Raja, Mohan; Abduljaleel, Zainularifeen; Dass, Lawrence Arockiasamy

    2014-10-31

    A novel electroactive shape memory polymer nanocomposite of epoxidized linseed oil plasticized polylactic acid and multi-walled carbon nanotubes (MWCNTs) was prepared by a combination of solution blending, solvent cast technique, and hydraulic hot press moulding. In this study, polylactic acid (PLA) was first plasticized by epoxidized linseed oil (ELO) in order to overcome the major limitations of PLA, such as high brittleness, low toughness, and low tensile elongation. Then, MWCNTs were incorporated into the ELO plasticized PLA matrix at three different loadings (2, 3 and 5 wt. %), with the aim of making the resulting nanocomposites electrically conductive. The addition of ELO decreased glass transition temperature, and increased the elongation and thermal degradability of PLA, as shown in the results of differential scanning calorimetry (DSC), tensile test, and thermo gravimetric analysis (TGA). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to observe surface morphology, topography, and the dispersion of MWCNTs in the nanocomposite. Finally, the electroactive-shape memory effect (electroactive-SME) in the resulting nanocomposite was investigated by a fold-deploy "U"-shape bending test. As per the results, the addition of both ELO and MWCNTs to PLA matrix seemed to enhance its overall properties with a great deal of potential in improved shape memory. The 3 wt. % MWCNTs-reinforced nanocomposite system, which showed 95% shape recovery within 45 s at 40 DC voltage, is expected to be used as a preferential polymeric nanocomposite material in various actuators, sensors and deployable devices.

  9. Cell-surface engineering by a conjugation-and-release approach based on the formation and cleavage of oxime linkages upon mild electrochemical oxidation and reduction.

    Science.gov (United States)

    Pulsipher, Abigail; Dutta, Debjit; Luo, Wei; Yousaf, Muhammad N

    2014-09-01

    We report a strategy to rewire cell surfaces for the dynamic control of ligand composition on cell membranes and the modulation of cell-cell interactions to generate three-dimensional (3D) tissue structures applied to stem-cell differentiation, cell-surface tailoring, and tissue engineering. We tailored cell surfaces with bioorthogonal chemical groups on the basis of a liposome-fusion and -delivery method to create dynamic, electroactive, and switchable cell-tissue assemblies through chemistry involving chemoselective conjugation and release. Each step to modify the cell surface: activation, conjugation, release, and regeneration, can be monitored and modulated by noninvasive, label-free analytical techniques. We demonstrate the utility of this methodology by the conjugation and release of small molecules to and from cell surfaces and by the generation of 3D coculture spheroids and multilayered cell tissues that can be programmed to undergo assembly and disassembly on demand. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Externally controlled triggered-release of drug from PLGA micro and nanoparticles.

    Directory of Open Access Journals (Sweden)

    Xin Hua

    Full Text Available Biofilm infections are extremely hard to eradicate and controlled, triggered and controlled drug release properties may prolong drug release time. In this study, the ability to externally control drug release from micro and nanoparticles was investigated. We prepared micro/nanoparticles containing ciprofloxacin (CIP and magnetic nanoparticles encapsulated in poly (lactic-co-glycolic acid PLGA. Both micro/nanoparticles were observed to have narrow size distributions. We investigated and compared their passive and externally triggered drug release properties based on their different encapsulation structures for the nano and micro systems. In passive release studies, CIP demonstrated a fast rate of release in first 2 days which then slowed and sustained release for approximately 4 weeks. Significantly, magnetic nanoparticles containing systems all showed ability to have triggered drug release when exposed to an external oscillating magnetic field (OMF. An experiment where the OMF was turned on and off also confirmed the ability to control the drug release in a pulsatile manner. The magnetically triggered release resulted in a 2-fold drug release increase compared with normal passive release. To confirm drug integrity following release, the antibacterial activity of released drug was evaluated in Pseudomonas aeruginosa biofilms in vitro. CIP maintained its antimicrobial activity after encapsulation and triggered release.

  11. Externally controlled triggered-release of drug from PLGA micro and nanoparticles.

    Science.gov (United States)

    Hua, Xin; Tan, Shengnan; Bandara, H M H N; Fu, Yujie; Liu, Siguo; Smyth, Hugh D C

    2014-01-01

    Biofilm infections are extremely hard to eradicate and controlled, triggered and controlled drug release properties may prolong drug release time. In this study, the ability to externally control drug release from micro and nanoparticles was investigated. We prepared micro/nanoparticles containing ciprofloxacin (CIP) and magnetic nanoparticles encapsulated in poly (lactic-co-glycolic acid) PLGA. Both micro/nanoparticles were observed to have narrow size distributions. We investigated and compared their passive and externally triggered drug release properties based on their different encapsulation structures for the nano and micro systems. In passive release studies, CIP demonstrated a fast rate of release in first 2 days which then slowed and sustained release for approximately 4 weeks. Significantly, magnetic nanoparticles containing systems all showed ability to have triggered drug release when exposed to an external oscillating magnetic field (OMF). An experiment where the OMF was turned on and off also confirmed the ability to control the drug release in a pulsatile manner. The magnetically triggered release resulted in a 2-fold drug release increase compared with normal passive release. To confirm drug integrity following release, the antibacterial activity of released drug was evaluated in Pseudomonas aeruginosa biofilms in vitro. CIP maintained its antimicrobial activity after encapsulation and triggered release.

  12. Synthesis of electroactive tetraaniline grafted polyethylenimine for tissue engineering

    Science.gov (United States)

    Dong, Shilei; Han, Lu; Cai, Muhang; Li, Luhai; Wei, Yan

    2015-07-01

    Tetraaniline grafted polyethylenimine (AT-PEI) was successfully synthesized in this study. Proton Nuclear Magnetic Resonance (1H NMR) Spectroscopy was used to determine the structure of carboxyl-capped aniline tetramer (AT-COOH) and AT-PEI. UV-Vis spectroscopy and Fourier transform infrared (FT-IR) spectroscopy were employed to characterize the absorption spectrum of the obtained AT-PEI samples. The morphology of AT-PEI copolymers in aqueous solution was determined by Scanning electron microscope (SEM). Moreover, AT-PEI copolymers demonstrated excellent solubility in aqueous solution and possessed electroactivity by cyclic voltammogram (CV) curves, which showed its potential application in the field of tissue engineering.

  13. Hydroxynaphthoquinone ultrathin films obtained by diazonium electroreduction: toward design of biosensitive electroactive interfaces.

    Science.gov (United States)

    March, Gregory; Reisberg, Steeve; Piro, Benoit; Pham, Minh-Chau; Fave, Claire; Noel, Vincent

    2010-05-01

    Electroactive 2-(phenylsulfanyl)-8-hydroxy-1,4-naphthoquinone has been electrodeposited via the reduction of the corresponding diazonium salt on Au electrodes. Surface characterizations by X-ray photoelectron spectroscopy (XPS) and infrared reflection-absorption spectroscopy (IRRAS) reveal that the mechanism of film deposition follows an aryl radical formation and its immobilization on the electrode surface. Electrochemical study shows that the surface coverage can be finely tuned (thickness between one and four layers) by adjusting the potential and the deposition time. By managing the potential applied when reducing diazonium in potentiostatic mode, the formed layer could mediate or not charge transfer. This is the first time that the films obtained by diazonium process are demonstrated to act as mediators in the growth process. Hence, with potentials higher than the formal potential of quinone group, very thin and homogeneous layers are obtained, whereas thicker films are formed when more cathodic potentials than that of quinone are applied. The possibility to manage the charge-transfer kinetics, the thickness, and the homogeneity of electroactive deposits is interesting in the scope of designing electrochemical transducers.

  14. Operational control of material release and discharges from nuclear power plant

    International Nuclear Information System (INIS)

    Szabo, I. C.; Ranga, T.; Daroczi, L.; Deme, S.; Kerekes, A.

    2003-01-01

    The operational control of radioactive materials during atmospheric release and aquatic discharge from nuclear power plant is a licensing criterion for NPPs. Originally at the Paks NPP the release control was based on activity limits for four groups of elements. These groups were noble gases, long living radio-aerosols, radioiodine and radiostrontium for atmospheric release and specified activity limit for beta emitters, strontium and tritium for aquatic discharge into Danube. These groups were controlled with proper sampling and/or measuring instrumentation. The limit for atmospheric release was given as a 30-day moving average, for liquid discharges the annual limit was stipulated. The new release and discharge limitation system is based on the environmental dose limitation. The dose constraint for Paks NPP is 90 Sv/year of the critical group for all release pathways and the investigation dose limit is equal to 27 Sv/year. The regulation did not subdivide the dose limit for atmospheric and liquid components but for operational control subdivision of dose limits for atmospheric release and aquatic discharge and shorter time period (one day-one month) seems to be useful. The subdivision can be based on past release data and/or previous activity limits. To satisfy dose below the investigation dose limit there should be a proper operation control level for each separately measured component and pathway belonging to reasonable time interval significantly shorter than one year. The main task of the NPP staff is elaboration of reasonable control levels and reference time intervals for different radionuclide and element groups to be used in operational control. Operational control levels are based on measured daily or monthly release rates. In case of noble gases, aerosols and iodine the daily release rates have several sharp peaks per year. Operational control levels give opportunity to detect these peaks for internal investigation purposes. Investigation release limits

  15. Massive radiological releases profoundly differ from controlled releases

    International Nuclear Information System (INIS)

    Pascucci-Cahen, Ludivine; Patrick, Momal

    2012-11-01

    Preparing for a nuclear accident implies understanding potential consequences. While many specialized experts have been working on different particular aspects, surprisingly little effort has been dedicated to establishing the big picture and providing a global and balanced image of all major consequences. IRSN has been working on the cost of nuclear accidents, an exercise which must strive to be as comprehensive as possible since any omission obviously underestimates the cost. It therefore provides (ideally) an estimate of all cost components, thus revealing the structure of accident costs, and hence sketching a global picture. On a French PWR, it appears that controlled releases would cause an 'economical' accident with limited radiological consequences when compared to other costs; in contrast, massive releases would trigger a major crisis with strong radiological consequences. The two types of crises would confront managers with different types of challenges. (authors)

  16. Controlled Release Formulations of Auxinic Herbicides

    Science.gov (United States)

    Kowalski, Witold J.; Siłowiecki, Andrzej.; Romanowska, Iwona; Glazek, Mariola; Bajor, Justyna; Cieciwa, Katarzyna; Rychter, Piotr

    2013-04-01

    Controlled release formulations are applied extensively for the release of active ingredients such as plant protection agents and fertilizers in response to growing concern for ecological problems associated with increased use of plant protection chemicals required for intensive agricultural practices [1]. We synthesized oligomeric mixtures of (R,S)-3-hydroxy butyric acid chemically bonded with 2,4-D, Dicamba and MCPA herbicides (HBA) respectively, and determined their molecular structure and molecular weight dispersion by the size exclusion chromatography, proton magnetic resonance spectrometry and electro-spray ionization mass spectrometry. Further we carried out bioassays of herbicidal effectiveness of the HBA herbicides vs. series of dicotyledonous weeds and crop injury tests [2, 3, 4]. Field bioassays were accomplished according to the EPPO standards [5]. Groups of representative weeds (the development stages in the BCCH scale: 10 - 30) were selected as targets. Statistical variabilities were assessed by the Fisher LSD test for plants treated with the studied herbicides in form of HBA oligomers, the reference herbicides in form of dimethyl ammonium salts (DMA), and untreated plants. No statistically significant differences in the crop injuries caused by the HBA vs. the DMA reference formulation were observed. The effectiveness of the HBA herbicides was lower through the initial period (ca. 2 weeks) relative to the DMA salts, but a significant increase in the effectiveness of the HBA systems followed during the remaining fraction of each assay. After 6 weeks all observed efficiencies approached 100%. The death of weeds treated with the HBA herbicides was delayed when compared with the DMA reference herbicides. The delayed uptake observed for the HBA oligomers relative to the DMA salts was due to controlled release phenomena. In case of the DMA salts the total amount of active ingredients was available at the target site. By contrast, the amount of an active

  17. Electrosprayed nanoparticle delivery system for controlled release

    Energy Technology Data Exchange (ETDEWEB)

    Eltayeb, Megdi, E-mail: megdi.eltayeb@sustech.edu [Department of Biomedical Engineering, Sudan University of Science and Technology, PO Box 407, Khartoum (Sudan); Stride, Eleanor, E-mail: eleanor.stride@eng.ox.ac.uk [Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Old Road Campus Research Building, Headington OX3 7DQ (United Kingdom); Edirisinghe, Mohan, E-mail: m.edirisinghe@ucl.ac.uk [Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom); Harker, Anthony, E-mail: a.harker@ucl.ac.uk [London Centre for Nanotechnology, Gordon Street, London WC1H 0AH (United Kingdom); Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

    2016-09-01

    This study utilises an electrohydrodynamic technique to prepare core-shell lipid nanoparticles with a tunable size and high active ingredient loading capacity, encapsulation efficiency and controlled release. Using stearic acid and ethylvanillin as model shell and active ingredients respectively, we identify the processing conditions and ratios of lipid:ethylvanillin required to form nanoparticles. Nanoparticles with a mean size ranging from 60 to 70 nm at the rate of 1.37 × 10{sup 9} nanoparticles per minute were prepared with different lipid:ethylvanillin ratios. The polydispersity index was ≈ 21% and the encapsulation efficiency ≈ 70%. It was found that the rate of ethylvanillin release was a function of the nanoparticle size, and lipid:ethylvanillin ratio. The internal structure of the lipid nanoparticles was studied by transmission electron microscopy which confirmed that the ethylvanillin was encapsulated within a stearic acid shell. Fourier transform infrared spectroscopy analysis indicated that the ethylvanillin had not been affected. Extensive analysis of the release of ethylvanillin was performed using several existing models and a new diffusive release model incorporating a tanh function. The results were consistent with a core-shell structure. - Highlights: • Electrohydrodynamic spraying is used to produce lipid-coated nanoparticles. • A new model is proposed for the release rates of active components from nanoparticles. • The technique has potential applications in food science and medicine. • Electrohydrodynamic processing controlled release lipid nanoparticles.

  18. Meltable magnetic biocomposites for controlled release

    Energy Technology Data Exchange (ETDEWEB)

    Müller, R., E-mail: robert.mueller@ipht-jena.de [Leibniz Institute of Photonic Technology (IPHT), P.O.B. 100239, Jena, D-07702 Germany (Germany); Zhou, M. [Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University of Jena, Humboldtstrasse 10, Jena, D-07743 Germany (Germany); Dellith, A. [Leibniz Institute of Photonic Technology (IPHT), P.O.B. 100239, Jena, D-07702 Germany (Germany); Liebert, T.; Heinze, T. [Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University of Jena, Humboldtstrasse 10, Jena, D-07743 Germany (Germany)

    2017-06-01

    New biocompatible composites with adjustable melting point in the range of 30–140 °C, consisting of magnetite nanoparticles embedded into a matrix of meltable dextran fatty acid ester are presented which can be softened under an induced alternating magnetic field (AMF). The chosen thermoplastic magnetic composites have a melting range close to human body temperature and can be easily shaped into disk or coating film under melting. The composite disks were loaded with green fluorescent protein (GFP) as a model protein. Controlled release of the protein was realized with high frequent alternating magnetic field of 20 kA/m at 400 kHz. These results showed that under an AMF the release of GFP from magnetic composite was accelerated compared to the control sample without exposure to AMF. Furthermore a texturing of particles in the polymer matrix by a static magnetic field was investigated. - Highlights: • Thermoplastic biocomposite are prepared from dextran ester and magnetite particles. • The composite can be heated by an AC magnetic field above the melting temperature. • In molten state texturing of particles is possible and improves the heating ability. • The biopolymer could be used as a remote controlled matrix for protein release.

  19. MWCNTs-Reinforced Epoxidized Linseed Oil Plasticized Polylactic Acid Nanocomposite and Its Electroactive Shape Memory Behaviour

    Directory of Open Access Journals (Sweden)

    Javed Alam

    2014-10-01

    Full Text Available A novel electroactive shape memory polymer nanocomposite of epoxidized linseed oil plasticized polylactic acid and multi-walled carbon nanotubes (MWCNTs was prepared by a combination of solution blending, solvent cast technique, and hydraulic hot press moulding. In this study, polylactic acid (PLA was first plasticized by epoxidized linseed oil (ELO in order to overcome the major limitations of PLA, such as high brittleness, low toughness, and low tensile elongation. Then, MWCNTs were incorporated into the ELO plasticized PLA matrix at three different loadings (2, 3 and 5 wt. %, with the aim of making the resulting nanocomposites electrically conductive. The addition of ELO decreased glass transition temperature, and increased the elongation and thermal degradability of PLA, as shown in the results of differential scanning calorimetry (DSC, tensile test, and thermo gravimetric analysis (TGA. Scanning electron microscopy (SEM and atomic force microscopy (AFM were used to observe surface morphology, topography, and the dispersion of MWCNTs in the nanocomposite. Finally, the electroactive-shape memory effect (electroactive-SME in the resulting nanocomposite was investigated by a fold-deploy “U”-shape bending test. As per the results, the addition of both ELO and MWCNTs to PLA matrix seemed to enhance its overall properties with a great deal of potential in improved shape memory. The 3 wt. % MWCNTs-reinforced nanocomposite system, which showed 95% shape recovery within 45 s at 40 DC voltage, is expected to be used as a preferential polymeric nanocomposite material in various actuators, sensors and deployable devices.

  20. Graphene oxide directed in-situ synthesis of Prussian blue for non-enzymatic sensing of hydrogen peroxide released from macrophages

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Weiwei; Zhu, Qionghua; Gao, Fei; Gao, Feng [College of Chemistry and Environment, Fujian Province Key Laboratory of Morden Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China); Huang, Jiafu; Pan, Yutian [College of Biological Science and Technology, Minnan Normal University, Zhangzhou 363000 (China); Wang, Qingxiang, E-mail: axiang236@126.com [College of Chemistry and Environment, Fujian Province Key Laboratory of Morden Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China)

    2017-03-01

    A novel electrochemical non-enzymatic hydrogen peroxide (H{sub 2}O{sub 2}) sensor has been developed based on Prussian blue (PB) and electrochemically reduced graphene oxide (ERGO). The GO was covalently modified on glassy carbon electrode (GCE), and utilized as a directing platform for in-situ synthesis of electroactive PB. Then the GO was electrochemically treated to reduction form to improve the effective surface area and electroactivity of the sensing interface. The fabrication process was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). The results showed that the rich oxygen containing groups play a crucial role for the successful synthesis of PB, and the obtained PB layer on the covalently immobilized GO has good stability. Electrochemical sensing assay showed that the modified electrode had tremendous electrocatalytic property for the reduction of H{sub 2}O{sub 2}. The steady-state current response increased linearly with H{sub 2}O{sub 2} concentrations from 5 μM to 1 mM with a fast response time (less than 3 s). The detection limit was estimated to be 0.8 μM. When the sensor was applied for determination of H{sub 2}O{sub 2} released from living cells of macrophages, satisfactory results were achieved. - Highlights: • Covalent method was applied for immobilization of GO on glassy carbon electrode. • GO directed in-situ synthesis of electroactive PB. • PB-ERGO composite shows high electrocatalytic activity toward H{sub 2}O{sub 2}. • The modified biosensor is capable of detecting H{sub 2}O{sub 2} released from living macrophages.

  1. Approach for discrimination and quantification of electroactive species: kinetics difference revealed by higher harmonics of Fourier transformed sinusoidal voltammetry.

    Science.gov (United States)

    Fang, Yishan; Huang, Xinjian; Wang, Lishi

    2015-01-06

    Discrimination and quantification of electroactive species are traditionally realized by a potential difference which is mainly determined by thermodynamics. However, the resolution of this approach is limited to tens of millivolts. In this paper, we described an application of Fourier transformed sinusoidal voltammetry (FT-SV) that provides a new approach for discrimination and quantitative evaluation of electroactive species, especially thermodynamic similar ones. Numerical simulation indicates that electron transfer kinetics difference between electroactive species can be revealed by the phase angle of higher order harmonics of FT-SV, and the difference can be amplified order by order. Thus, even a very subtle kinetics difference can be amplified to be distinguishable at a certain order of harmonics. This method was verified with structurally similar ferrocene derivatives which were chosen as the model systems. Although these molecules have very close redox potential (harmonics. The results demonstrated the feasibility and reliability of the method. It was also implied that the combination of the traditional thermodynamic method and this kinetics method can form a two-dimension resolved detection method, and it has the potential to extend the resolution of voltammetric techniques to a new level.

  2. Controlled Release Formulation of Indomethacin Prepared With Bee ...

    African Journals Online (AJOL)

    Erah

    2010-12-27

    Dec 27, 2010 ... Results: The results show that, although the release rate of formulations F1 - F7 did not show any ... Keywords: Propolis (bee glue), Indomethacin, Controlled release, Zero order kinetics, Waxy materials ... focus of interest.

  3. Biologically Inspired Technology Using Electroactive Polymers (EAP)

    Science.gov (United States)

    Bar-Cohen, Yoseph

    2006-01-01

    Evolution allowed nature to introduce highly effective biological mechanisms that are incredible inspiration for innovation. Humans have always made efforts to imitate nature's inventions and we are increasingly making advances that it becomes significantly easier to imitate, copy, and adapt biological methods, processes and systems. This brought us to the ability to create technology that is far beyond the simple mimicking of nature. Having better tools to understand and to implement nature's principles we are now equipped like never before to be inspired by nature and to employ our tools in far superior ways. Effectively, by bio-inspiration we can have a better view and value of nature capability while studying its models to learn what can be extracted, copied or adapted. Using electroactive polymers (EAP) as artificial muscles is adding an important element to the development of biologically inspired technologies.

  4. Electroactive polymer (EAP) actuators for planetary applications

    Science.gov (United States)

    Bar-Cohen, Yoseph; Leary, Sean P.; Shahinpoor, Mohsen; Harrison, Joycelyn S.; Smith, J.

    1999-05-01

    NASA is seeking to reduce the mass, size, consumed power, and cost of the instrumentation used in its future missions. An important element of many instruments and devices is the actuation mechanism and electroactive polymers (EAP) are offering an effective alternative to current actuators. In this study, two families of EAP materials were investigated, including bending ionomers and longitudinal electrostatically driven elastomers. These materials were demonstrated to effectively actuate manipulation devices and their performance is being enhanced in this on-going study. The recent observations are reported in this paper, include the operation of the bending-EAP at conditions that exceed the harsh environment on Mars, and identify the obstacles that its properties and characteristics are posing to using them as actuators. Analysis of the electrical characteristics of the ionomer EAP showed that it is a current driven material rather than voltage driven and the conductivity distribution on the surface of the material greatly influences the bending performance. An accurate equivalent circuit modeling of the ionomer EAP performance is essential for the design of effective drive electronics. The ionomer main limitations are the fact that it needs to be moist continuously and the process of electrolysis that takes place during activation. An effective coating technique using a sprayed polymer was developed extending its operation in air from a few minutes to about four months. The coating technique effectively forms the equivalent of a skin to protect the moisture content of the ionomer. In parallel to the development of the bending EAP, the development of computer control of actuated longitudinal EAP has been pursued. An EAP driven miniature robotic arm was constructed and it is controlled by a MATLAB code to drop and lift the arm and close and open EAP fingers of a 4-finger gripper.

  5. Biomimetic actuators using electroactive polymers (EAP) as artificial muscles

    Science.gov (United States)

    Bar-Cohen, Yoseph

    2006-01-01

    Evolution has resolved many of nature's challenges leading to lasting solutions with maximal performance and effective use of resources. Nature's inventions have always inspired human achievements leading to effective materials, structures, tools, mechanisms, processes, algorithms, methods, systems and many other benefits. The field of mimicking nature is known as Biomimetics and one of its topics includes electroactive polymers that gain the moniker artificial muscles. Integrating EAP with embedded sensors, self-repair and many other capabilities that are used in composite materials can add greatly to the capability of smart biomimetic systems. Such development would enable fascinating possibilities potentially turning science fiction ideas into engineering reality.

  6. Controlled release of diuron from an alginate-bentonite formulation: water release kinetics and soil mobility study.

    Science.gov (United States)

    Fernández-Pérez, M; Villafranca-Sánchez, M; González-Pradas, E; Flores-Céspedes, F

    1999-02-01

    The herbicide diuron was incorporated in alginate-based granules to obtain controlled release (CR) properties. The standard formulation (alginate-herbicide-water) was modified by the addition of different sorbents. The effect on diuron release rate caused by incorporation of natural and acid-treated bentonites in alginate formulation was studied by immersion of the granules in water under static conditions. The release of diuron was diffusion-controlled. The time taken for 50% release of active ingredient to be released into water, T(50), was calculated for the comparison of formulations. The addition of bentonite to the alginate-based formulation produced the higher T(50) values, indicating slower release of the diuron. The mobility of technical and formulated diuron was compared by using soil columns. The use of alginate-based CR formulations containing bentonite produced a less vertical distribution of the active ingredient as compared to the technical product and commercial formulation. Sorption capacities of the various soil constituents for diuron were also determined using batch experiments.

  7. Novel electroactive PVA-TOCN actuator that is extremely sensitive to low electrical inputs

    International Nuclear Information System (INIS)

    Wang, Fan; Kim, Si-Seup; Kee, Chang-Doo; Shen, Yun-De; Oh, Il-Kwon

    2014-01-01

    A novel electroactive biopolymer actuator was developed based on a cross-linked ionic networking membrane of TEMPO-oxidized bacterial cellulose nanofibers (TOCNs) and polyvinyl alcohol (PVA). Ionic liquids were added to develop an air-working artificial muscle and to enhance the performance of the PVA-TOCN actuator. Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) conducting layers were deposited on the top and bottom surfaces of the PVA-TOCN membrane via a simple dipping and drying method. The electroactive PVA-TOCN actuator under both step and harmonic electrical inputs shows much larger tip displacements and faster bending deformation than the pure TOCN actuator. The cross-linking reaction between PVA and TOCN was observed in the Fourier transform–near-infrared (FT-IR) spectrum of the PVA-TOCN networking membrane. Scanning electron microscopy (SEM), x-ray diffusion (XRD), thermogravimetric analysis (TGA) and tensile and ion conductivity testing results for the PVA-TOCN membrane were compared with those of pristine TOCN. Most important, the PVA-TOCN actuator shows much larger bending deformation under even extremely low input voltages, and this could be attributed to the cross-linking mechanism and the greater flexibility resulting from the synergistic effects between PVA and TOCN. (papers)

  8. Creep-Fatigue Relationsihps in Electroactive Polymer Systems and Predicted Effects in an Actuator Design

    Science.gov (United States)

    Vinogradov, Aleksandra M.; Ihlefeld, Curtis M.; Henslee, Issac

    2009-01-01

    The paper concerns the time-dependent behavior of electroactive polymers (EAP) and their use in advanced intelligent structures for space exploration. Innovative actuator design for low weight and low power valves required in small plants planned for use on the moon for chemical analysis is discussed. It is shown that in-depth understanding of cyclic loading effects observed through accelerated creep rates due to creep-fatigue interaction in polymers is critical in terms of proper functioning of EAP based actuator devices. In the paper, an overview of experimental results concerning the creep properties and cyclic creep response of a thin film piezoelectric polymer polyvinylidene fluoride (PVDF) is presented. The development of a constitutive creep-fatigue interaction model to predict the durability and service life of electroactive polymers is discussed. A novel method is proposed to predict damage accumulation and fatigue life of polymers under oyclic loading conditions in the presence of creep. The study provides a basis for ongoing research initiatives at the NASA Kennedy Space Center in the pursuit of new technologies using EAP as active elements for lunar exploration systems.

  9. Building Adjustable Pre-storm Reservoir Flood-control Release Rules

    Science.gov (United States)

    Yang, Shun-Nien; Chang, Li-Chiu; Chang, Fi-John; Hsieh, Cheng-Daw

    2017-04-01

    Typhoons hit Taiwan several times every year, which could cause serious flood disasters. Because mountainous terrains and steep landforms can rapidly accelerate the speed of flood flow during typhoon events, rivers cannot be a stable source of water supply. Reservoirs become the most effective floodwater storage facilities for alleviating flood damages in Taiwan. The pre-storm flood-control release can significantly increase reservoir storage capacity available to store floodwaters for reducing downstream flood damage, while the uncertainties of total forecasted rainfalls are very high in different stages of an oncoming typhoon, which may cause the risk of water shortage in the future. This study proposes adjustable pre-storm reservoir flood-control release rules in three designed operating stages with various hydrological conditions in the Feitsui Reservoir, a pivot reservoir for water supply to Taipei metropolitan in Taiwan, not only to reduce the risk of reservoir flood control and downstream flooding but also to consider water supply. The three operating stages before an oncoming typhoon are defined upon the timings when: (1) typhoon news is issued (3-7days before typhoon hit); (2) the sea warning is issued (2-4 days before typhoon hit); and (3) the land warning is issued (1-2 days before typhoon hit). We simulate 95 historical typhoon events with 3000 initial water levels and build some pre-storm flood-control release rules to adjust the amount of pre-release based on the total forecasted rainfalls at different operating stages. A great number of simulations (68.4 millions) are conducted to extract their major consequences and then build the adjustable pre-storm reservoir flood-control release rules. Accordingly, given a total forecasted rainfall and a water level, reservoir decision makers can easily identify the corresponding rule to tell the amount of pre-release in any stage. The results show that the proposed adjustable pre-release rules can effectively

  10. Fabrication and characterization of cellulose nanocrystal based transparent electroactive polyurethane

    Science.gov (United States)

    Ko, Hyun-U.; Kim, Hyun Chan; Kim, Jung Woong; Zhai, Lindong; Jayaramudu, Tippabattini; Kim, Jaehwan

    2017-08-01

    This paper reports cellulose nanocrystal (CNC) based transparent and electroactive polyurethane (CPPU), suitable for actively tunable optical lens. CNC is used for high dielectric filler to improve electromechanical behavior of CPPU. For high transparency and homogeneous distribution of CNC in polyurethane, CNC-poly[di(ethylene glycol) adipate] is used to play a role of polyol and isocyanate salt. The fabricated CPPU exhibits high transparency (>90%) and 10% of electromechanical strain under 3 V μm-1 electric field. Mechanical, dielectric properties as well as physical and chemical characteristics are investigated to prove the electromechanical behavior of CPPU.

  11. Critical review of controlled release packaging to improve food safety and quality.

    Science.gov (United States)

    Chen, Xi; Chen, Mo; Xu, Chenyi; Yam, Kit L

    2018-03-19

    Controlled release packaging (CRP) is an innovative technology that uses the package to release active compounds in a controlled manner to improve safety and quality for a wide range of food products during storage. This paper provides a critical review of the uniqueness, design considerations, and research gaps of CRP, with a focus on the kinetics and mechanism of active compounds releasing from the package. Literature data and practical examples are presented to illustrate how CRP controls what active compounds to release, when and how to release, how much and how fast to release, in order to improve food safety and quality.

  12. Synthesis, characterization and antioxidant activity of a novel electroactive and biodegradable polyurethane for cardiac tissue engineering application.

    Science.gov (United States)

    Baheiraei, Nafiseh; Yeganeh, Hamid; Ai, Jafar; Gharibi, Reza; Azami, Mahmoud; Faghihi, Faezeh

    2014-11-01

    There has been a growing trend towards applying conducting polymers for electrically excitable cells to increase electrical signal propagation within the cell-loaded substrates. A novel biodegradable electroactive polyurethane containing aniline pentamer (AP-PU) was synthesized and fully characterized by spectroscopic methods. To tune the physico-chemical properties and biocompatibility, the AP-PU was blended with polycaprolactone (PCL). The presence of electroactive moieties and the electroactivity behavior of the prepared films were confirmed by UV-visible spectroscopy and cyclic voltammetry. A conventional four probe analysis demonstrated the electrical conductivity of the films in the semiconductor range (~10(-5)S/cm). MTT assays using L929 mouse fibroblast and human umbilical vein endothelial cells (HUVECs) showed that the prepared blend (PB) displayed more cytocompatibility compared with AP-PU due to the introduction of a biocompatible PCL moiety. The in vitro cell culture also confirmed that PB was as supportive as tissue culture plate. The antioxidant activity of the AP-PU was proved using 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay by employing UV-vis spectroscopy. In vitro degradation tests conducted in phosphate-buffered saline, pH7.4 and pH5.5, proved that the films were also biodegradable. The results of this study have highlighted the potential application of this bioelectroactive polyurethane as a platform substrate to study the effect of electrical signals on cell activities and to direct desirable cell function for tissue engineering applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Bistable electroactive polymer for refreshable Braille display with improved actuation stability

    Science.gov (United States)

    Niu, Xiaofan; Brochu, Paul; Stoyanov, Hristiyan; Yun, Sung Ryul; Pei, Qibing

    2012-04-01

    Poly(t-butyl acrylate) is a bistable electroactive polymer (BSEP) capable of rigid-to-rigid actuation. The BSEP combines the large-strain actuation of dielectric elastomers with shape memory property. We have introduced a material approach to overcome pull-in instability in poly(t-butyl acrylate) that significantly improves the actuation lifetime at strains greater than 100%. Refreshable Braille display devices with size of a smartphone screen have been fabricated to manifest a potential application of the BSEP. We will report the testing results of the devices by a Braille user.

  14. Calcium modified edible Canna (Canna edulis L) starch for controlled released matrix

    Science.gov (United States)

    Putri, A. P.; Ridwan, M.; Darmawan, T. A.; Darusman, F.; Gadri, A.

    2017-07-01

    Canna edulis L starch was modified with calcium chloride in order to form controlled released matrix. Present study aim to analyze modified starch characteristic. Four different formulation of ondansetron granules was used to provide dissolution profile of controlled released, two formula consisted of 15% and 30% modified starch, one formula utilized matrix reference standards and the last granules was negative control. Methocel-hydroxypropyl methyl cellulose was used as controlled released matrix reference standards in the third formula. Calcium starch was synthesized in the presence of sodium hydroxide to form gelatinized mass and calcium chloride as the cross linking agent. Physicochemical and dissolution properties of modified starch for controlled released application were investigated. Modified starch has higher swelling index, water solubility and compressibility index. Three of four different formulation of granules provide dissolution profile of controlled released. The profiles indicate granules which employed calcium Canna edulis L starch as matrix are able to resemble controlled drug released profile of matrix reference, however their bigger detain ability lead to lower bioavailability.

  15. Massive radiological releases profoundly differ from controlled releases

    International Nuclear Information System (INIS)

    Pascucci-Cahen, Ludivine; Patrick, Momal

    2013-01-01

    In this article, the authors report identification and assessment of different types of costs associated with nuclear accidents. They first outline that these cost assessments must be as exhaustive or comprehensive as possible. While referring to past accidents, they define the different categories of costs: on-site costs (decontamination and dismantling, electricity not produced on the site), off-site costs (health costs, psychological costs, farming losses), image-related costs (impact on food and farm product exports, decrease of other exports), costs related to energy production, costs related to contaminated areas (refugees, lands). They give an assessment of a severe nuclear accident (i.e. an accident with important but controlled radiological releases) in France and outline that it would be a national catastrophe which could be however managed. They discuss the possible variations of the estimated costs. Then, they show that a major accident (i.e. an accident with massive radiological releases) in France would be an unmanageable European catastrophe because of the radiological consequences, of high economic costs, and of huge losses

  16. SOL-Gel microspheres and nanospheres for controlled release applications

    International Nuclear Information System (INIS)

    Barbe, C.; Beyer, R.; Kong, L.; Blackford, M.; Trautman, R.; Bartlett, J.

    2002-01-01

    We present a novel approach to the synthesis of inorganic sol-gel microspheres for encapsulating organic and bioactive molecules, and controlling their subsequent release kinetics. The bioactive species are incorporated, at ambient temperature, into the inorganic particles using an emulsion gelation process. Independent control of the release rate (by adapting the nanostructure of the internal pore network to the physico-chemical properties of the bioactive molecules) and particle size (by tailoring the emulsion chemistry) is demonstrated. Sol-gel chemistry has been shown to be a flexible technique for producing inorganic silica matrices with tailored microstructures, which can be used for the encapsulation and controlled release of organic and bioactive molecules. The present paper extends this concept by combining sol-gel chemistry with an emulsion approach for producing inorganic particles with controlled dimensions, and demonstrates how the particle size and microstructure can be independently controlled. Sol-Gel Chemistry and Encapsulation of Model Compounds. A stock solution of 4-(2-hydroxy-l-naphthylazo) benzene sulfonic acid (Orange II) was produced by dissolving Orange II in water (0.1 wt%), and adjusting the pH to the required value. Sol-gel solutions were subsequently prepared by mixing the aqueous solution with tetramethylorthosilicate (TMOS) and methanol (MeOH), to achieve H 2 O:TMOS (W] and MeOH:TMOS mole ratios (D) of four. The resulting solution was stirred and left to age at ambient temperature for one day. A transparent emulsion was prepared by mixing selected surfactants and organic solvents. The surfactants used included sorbitan monooleate, sorbitan monolaurate and bis-2-ethylhexylsulfo-succinate (AOT), while the organic phase was typically chosen from the group consisting of kerosene, hexane, heptane, octane, decane, dodecane and cyclohexane. The sol-gel solution was added to the emulsion, and the resulting mixture was stirred at 500 rpm for

  17. Design and characterization of controlled release tablet of metoprolol

    Directory of Open Access Journals (Sweden)

    Gautam Singhvi

    2012-01-01

    Full Text Available Metoprolol succinate is a selective beta-adrenergic receptor blocker useful in treatment of hypertension, angina and heart failure. The purpose of the present work was to design and evaluate controlled release matrix type tablet of Metoprolo succinate using HPMC K15M and Eudragit (RLPO and RSPO as a matrix forming agents. Effect of various polymer alone and combinations were studied in pH 1.2 buffer using USP type II paddle at 50 rpm. HPMC was used to form firm gel with Eudragit polymer. Formulation with Equal proportion (1:1 of Eudragit RSPO and RLPO showed optimum drug release t50 =7 hrs and t100 =16 hrs indicate optimum permeability for drug release from matrix. The drug release mechanism was predominantly found to be Non-Fickian diffusion controlled.

  18. Evaluation of olibanum and its resin as rate controlling matrix for controlled release of diclofenac

    OpenAIRE

    Chowdary KPR; Mohapatra P; Murali Krishna M

    2006-01-01

    Olibanum and its resin and carbohydrate fractions were evaluated as rate controlling matrix materials in tablets for controlled release of diclofenac. Diclofenac matrix tablets were formulated employing olibanum and its resin and carbohydrate fractions in different concentrations and the tablets were evaluated for various tablet characters including drug release kinetics and mechanism. Olibanum and its resin component exhibited excellent retarding effect on drug release from the matrix tablet...

  19. Preparation and characterization of controlled-release fertilizers coated with marine polysaccharide derivatives

    Science.gov (United States)

    Wang, Jing; Liu, Song; Qin, Yukun; Chen, Xiaolin; Xing, Rong'e.; Yu, Huahua; Li, Kecheng; Li, Pengcheng

    2017-09-01

    Encapsulation of water-soluble nitrogen fertilizers by membranes can be used to control the release of nutrients to maximize the fertilization effect and reduce environmental pollution. In this research, we formulated a new double-coated controlled-release fertilizer (CRF) by using food-grade microcrystalline wax (MW) and marine polysaccharide derivatives (calcium alginate and chitosan-glutaraldehyde copolymer). The pellets of water-soluble nitrogen fertilizer were coated with the marine polysaccharide derivatives and MW. A convenient and eco-friendly method was used to prepare the CRF. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the morphology and composition of the products. The nitrogen-release properties were determined in water using UV-Vis spectrophotometry. The controlled-release properties of the fertilizer were improved dramatically after coating with MW and the marine polysaccharide derivatives. The results show that the double-coated CRFs can release nitrogen in a controlled manner, have excellent controlled-release features, and meet the European Standard for CRFs.

  20. Controlled release of insect sex pheromones from paraffin wax and emulsions.

    Science.gov (United States)

    Atterholt, C A; Delwiche, M J; Rice, R E; Krochta, J M

    1999-02-22

    Paraffin wax and aqueous paraffin emulsions can be used as controlled release carriers for insect sex pheromones for mating disruption of orchard pests. Paraffin can be applied at ambient temperature as an aqueous emulsion, adheres to tree bark or foliage, releases pheromone for an extended period of time, and will slowly erode from bark and biodegrade in soil. Pheromone emulsions can be applied with simple spray equipment. Pheromone release-rates from paraffin were measured in laboratory flow-cell experiments. Pheromone was trapped from an air stream with an adsorbent, eluted periodically, and quantified by gas chromatography. Pheromone release from paraffin was partition-controlled, providing a constant (zero-order) release rate. A typical paraffin emulsion consisted of 30% paraffin, 4% pheromone, 4% soy oil, 1% vitamin E, 2% emulsifier, and the balance water. Soy oil and vitamin E acted as volatility suppressants. A constant release of oriental fruit moth pheromone from paraffin emulsions was observed in the laboratory for more than 100 days at 27 degreesC, with release-rates ranging from 0.4 to 2 mg/day, depending on the concentration and surface area of the dried emulsion. The use of paraffin emulsions is a viable method for direct application of insect pheromones for mating disruption. Sprayable formulations can be designed to release insect pheromones to the environment at a rate necessary for insect control by mating disruption. At temperatures below 38 degreesC, zero-order release was observed. At 38 degreesC and higher, pheromone oxidation occurred. A partition-controlled release mechanism was supported by a zero-order pheromone release-rate, low air/wax partition coefficients, and pheromone solubility in paraffin.

  1. Sol-gel encapsulation for controlled drug release and biosensing

    Science.gov (United States)

    Fang, Jonathan

    The main focus of this dissertation is to investigate the use of sol-gel encapsulation of biomolecules for controlled drug release and biosensing. Controlled drug release has advantages over conventional therapies in that it maintains a constant, therapeutic drug level in the body for prolonged periods of time. The anti-hypertensive drug Captopril was encapsulated in sol-gel materials of various forms, such as silica xerogels and nanoparticles. The primary objective was to show that sol-gel silica materials are promising drug carriers for controlled release by releasing Captopril at a release rate that is within a therapeutic range. We were able to demonstrate desired release for over a week from Captopril-doped silica xerogels and overall release from Captopril-doped silica nanoparticles. As an aside, the antibiotic Vancomycin was also encapsulated in these porous silica nanoparticles and desired release was obtained for several days in-vitro. The second part of the dissertation focuses on immobilizing antibodies and proteins in sol-gel to detect various analytes, such as hormones and amino acids. Sol-gel competitive immunoassays on antibody-doped silica xerogels were used for hormone detection. Calibration for insulin and C-peptide in standard solutions was obtained in the nM range. In addition, NASA-Ames is also interested in developing a reagentless biosensor using bacterial periplasmic binding proteins (bPBPs) to detect specific biomarkers, such as amino acids and phosphate. These bPBPs were doubly labeled with two different fluorophores and encapsulated in silica xerogels. Ligand-binding experiments were performed on the bPBPs in solution and in sol-gel. Ligand-binding was monitored by fluorescence resonance energy transfer (FRET) between the two fluorophores on the bPBP. Titration data show that one bPBP has retained its ligand-binding properties in sol-gel.

  2. Membrane Separated Flow Cell for Parallelized Electrochemical Impedance Spectroscopy and Confocal Laser Scanning Microscopy to Characterize Electro-Active Microorganisms

    International Nuclear Information System (INIS)

    Stöckl, Markus; Schlegel, Christin; Sydow, Anne; Holtmann, Dirk; Ulber, Roland; Mangold, Klaus-Michael

    2016-01-01

    Highlights: • Development of a membrane separated electrochemical flow cell. • Simultaneous combination of EIS and CLSM. • Monitoring of bacterial cell attachment to anode of MFC. • Cell attachment of Shewanella oneidensis is shown. - Abstract: Understanding the attachment of electro-active bacteria to electrode surfaces and their subsequent biofilm formation is one of the major challenges for the establishment of bacterial bioelectrochemial systems (BES). For a constant observation of biofilm growth, providing information on different stages of biofilm formation, continuous monitoring methods are required. In this paper a combination of two powerful analytical methods, Electrochemical Impedance Spectroscopy (EIS) and Confocal Laser Scanning Microscopy (CLSM), for biofilm monitoring is presented. A custom-built flow cell with a transparent indium tin oxide working electrode (WE) was constructed allowing monitoring of cell attachment to a working electrode simultaneously by EIS and CLSM. Cyclic Voltammetry (CV) and EIS of an iron (II)/iron (III) redox couple indicate that the flow cell is suitable for electrochemical experiments. An engineered Shewanella oneidensis MR-1 (ATCC700550) producing eGFP was used as electro-active model organism to demonstrate the practical application of the flow cell as BES to monitor cell attachment simultaneously with EIS and CLSM. Applying the flow cell as MFC (transparent working electrode poised as anode) produced a typical current curve for such a system. From the equivalent circuit used to interpret EIS data the charge transfer resistance R CT is sensitive to attachment of microorganisms. Fitted R CT was increased initially after cell inoculation and then lowered constantly with progressing experimental time. In parallel taken CLSM images show that bacteria already adhered to the WE 5 min after inoculation. A mono- respectively bilayer of electro-active cells was observed after 17 h on the WE surface. With the presented

  3. Controlled release of curcumin from poly(HEMA-MAPA) membrane.

    Science.gov (United States)

    Caka, Müşerref; Türkcan, Ceren; Aktaş Uygun, Deniz; Uygun, Murat; Akgöl, Sinan; Denizli, Adil

    2017-05-01

    In this work, poly(HEMA-MAPA) membranes were prepared by UV-polymerization technique. These membranes were characterized by SEM, FTIR, and swelling studies. Synthesized membranes had high porous structure. These membranes were used for controlled release of curcumin which is already used as folk remedy and used as drug for some certain diseases and cancers. Curcumin release was investigated for various pHs and temperatures. Optimum drug release yield was found to be as 70% at pH 7.4 and 37 °C within 2 h period. Time-depended release of curcumin was also investigated and its slow release from the membrane demonstrated within 48 h.

  4. Controlled Pesticide Release from Porous Composite Hydrogels Based on Lignin and Polyacrylic Acid

    Directory of Open Access Journals (Sweden)

    Yajie Sun

    2016-01-01

    Full Text Available For the controlled release of pesticides, a novel composite porous hydrogel (LBPAA was prepared based on lignin and polyacrylic acid for use as the support frame of a pore structure for water delivery. The LBPAA was analyzed to determine its water-swelling and slow release properties. The controlled release properties of LBPAA were evaluated through experiments in relation to the cumulative release of pesticides, with particular emphasis on environmental effects and release models. The porous LBPAA hydrogel showed improved properties compared to polyacrylic acid, and could therefore be considered an efficient material for application in controlled release systems in agriculture.

  5. Release kinetics of tocopherol and quercetin from binary antioxidant controlled-release packaging films.

    Science.gov (United States)

    Chen, Xi; Lee, Dong Sun; Zhu, Xuntao; Yam, Kit L

    2012-04-04

    This paper investigated the feasibility of manipulating packaging polymers with various degrees of hydrophobicity to release two antioxidants, tocopherol and quercetin, at rates suitable for long-term inhibition of lipid oxidation in food. For example, one antioxidant can be released at a fast rate to provide short-term/intermediate protection, whereas the other antioxidant can be released at a slower rate to provide intermediate/long-term protection of lipid oxidation. Controlled-release packaging films containing tocopherol and quercetin were produced using ethylene vinyl alcohol (EVOH), ethylene vinyl acetate (EVA), low-density polyethylene (LDPE), and polypropylene (PP) polymers; the release of these antioxidants to 95% ethanol (a fatty food simulant) was measured using UV-vis spectrophotometry, and Fickian diffusion models with appropriate initial and boundary conditions were used to fit the data. For films containing only quercetin, the results show that the release of quercetin was much faster but lasted for a much shorter time for hydrophilic polymers (EVOH and EVA) than for hydrophobic polymers (LDPE and PP). For binary antioxidant films containing tocopherol and quercetin, the results show that tocopherol released more rapidly but for a shorter period of time than quercetin in LDPE and EVOH films, and the difference is more pronounced for LDPE films than EVOH films. The results also show the presence of tocopherol can accelerate the release of quercetin. Although none of the films produced is acceptable for long-term lipid oxidation inhibition, the study provides encouraging results suggesting that acceptable films may be produced in the future using polymer blend films.

  6. Poly(dimethylsiloxane) coatings for controlled drug release--polymer modifications.

    Science.gov (United States)

    Schulze Nahrup, J; Gao, Z M; Mark, J E; Sakr, A

    2004-02-11

    Modifications of endhydroxylated poly(dimethylsiloxane) (PDMS) formulations were studied for their ability to be applied onto tablet cores in a spray-coating process and to control drug release in zero-order fashion. Modifications of the crosslinker from the most commonly used tetraethylorthosilicate (TEOS) to the trifunctional 3-(2,3-epoxypropoxy)propyltrimethoxysilane (SIG) and a 1:1 mixture of the two were undertaken. Addition of methylpolysiloxane-copolymers were studied. Lactose, microcrystalline cellulose (MCC) and polyethylene glycol 8000 (PEG) were the channeling agents applied. The effects on dispersion properties were characterized by particle size distribution and viscosity. Mechanical properties of resulting free films were studied to determine applicability in a pan-coating process. Release of hydrochlorothiazide (marker drug) was studied from tablets coated in a lab-size conventional coating pan. All dispersions were found suitable for a spray-coating process. Preparation of free films showed that copolymer addition was not possible due to great decline in mechanical properties. Tablets coated with formulations containing PEG were most suitable to control drug release, at only 5% coating weight. Constant release rates could be achieved for formulations with up to 25% PEG; higher amounts resulted in a non-linear release pattern. Upon adding 50% PEG, a drug release of 63% over 24 h could be achieved.

  7. Immobilization and controlled release of drug using plasma polymerized thin film

    Energy Technology Data Exchange (ETDEWEB)

    Myung, Sung-Woon [Department of Dental Materials, School of Dentistry, MRC Center, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju (Korea, Republic of); Jung, Sang-Chul [Department of Environmental Engineering, Sunchon National University, Sunchon 540-742 (Korea, Republic of); Kim, Byung-Hoon, E-mail: kim5055@chosun.ac.kr [Department of Dental Materials, School of Dentistry, MRC Center, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju (Korea, Republic of)

    2015-06-01

    In this study, plasma polymerization of acrylic acid was employed to immobilize drug and control its release. Doxorubicin (DOX) was immobilized covalently on the glass surface deposited with plasma polymerized acrylic acid (PPAAc) thin film containing the carboxylic group. At first, the PPAAc thin film was coated on a glass surface at a pressure of 1.33 Pa and radio frequency (RF) discharge power of 20 W for 10 min. DOX was immobilized on the PPAAc deposition in a two environment of phosphate buffer saline (PBS) and dimethyl sulfoxide (DMSO) solutions. The DOX immobilized surface was characterized by scanning electron microscope, atomic force microscope and attenuated total reflection Fourier transform infrared spectroscopy. The DOX molecules were more immobilized in PBS than DMSO solution. The different immobilization and release profiles of DOX result from the solubility of hydrophobic DOX in aqueous and organic solutions. Second, in order to control the release of the drug, PPAAc thin film was covered over DOX dispersed layer. Different thicknesses and cross-linked PPAAc thin films by adjusting deposition time and RF discharge power were covered on the DOX layer dispersed. PPAAc thin film coated DOX layer reduced the release rate of DOX. The thickness control of plasma deposition allows controlling the release rate of drug. - Highlights: • Doxorubicin was immobilized on the surface of plasma polymerized acrylic acid thin film. • Release profile of doxorubicin was affected by aqueous and organic solutions. • Plasma polymerized acrylic acid thin film can be used to achieve controlled release.

  8. Immobilization and controlled release of drug using plasma polymerized thin film

    International Nuclear Information System (INIS)

    Myung, Sung-Woon; Jung, Sang-Chul; Kim, Byung-Hoon

    2015-01-01

    In this study, plasma polymerization of acrylic acid was employed to immobilize drug and control its release. Doxorubicin (DOX) was immobilized covalently on the glass surface deposited with plasma polymerized acrylic acid (PPAAc) thin film containing the carboxylic group. At first, the PPAAc thin film was coated on a glass surface at a pressure of 1.33 Pa and radio frequency (RF) discharge power of 20 W for 10 min. DOX was immobilized on the PPAAc deposition in a two environment of phosphate buffer saline (PBS) and dimethyl sulfoxide (DMSO) solutions. The DOX immobilized surface was characterized by scanning electron microscope, atomic force microscope and attenuated total reflection Fourier transform infrared spectroscopy. The DOX molecules were more immobilized in PBS than DMSO solution. The different immobilization and release profiles of DOX result from the solubility of hydrophobic DOX in aqueous and organic solutions. Second, in order to control the release of the drug, PPAAc thin film was covered over DOX dispersed layer. Different thicknesses and cross-linked PPAAc thin films by adjusting deposition time and RF discharge power were covered on the DOX layer dispersed. PPAAc thin film coated DOX layer reduced the release rate of DOX. The thickness control of plasma deposition allows controlling the release rate of drug. - Highlights: • Doxorubicin was immobilized on the surface of plasma polymerized acrylic acid thin film. • Release profile of doxorubicin was affected by aqueous and organic solutions. • Plasma polymerized acrylic acid thin film can be used to achieve controlled release

  9. Comparison of the dielectric electroactive polymer generator energy harvesting cycles

    DEFF Research Database (Denmark)

    Dimopoulos, Emmanouil; Trintis, Ionut; Munk-Nielsen, Stig

    2013-01-01

    The Dielectric ElectroActive Polymer (DEAP) generator energy harvesting cycles have been in the spotlight of the scientific interest for the past few years. Indeed, several articles have demonstrated thorough and comprehensive comparisons of the generator fundamental energy harvesting cycles......, namely Constant Charge (CC), Constant Voltage (CV) and Constant E-field (CE), based on averaged theoretical models. Yet, it has not been possible until present to validate the outcome of those comparisons via respective experimental results. In this paper, all three primary energy harvesting cycles...... are experimentally compared, based upon the coupling of a DEAP generator with a bidirectional non-isolated power electronic converter, by means of energy gain, energy harvesting efficiency and energy conversion efficiency....

  10. Controlled release of biofunctional substances by radiation-induced polymerization

    International Nuclear Information System (INIS)

    Yoshida, M.; Kumakura, M.; Kaetsu, I.

    1978-01-01

    The controlled release of potassium chloride from flat circular matrices made by radiation-induced polymerization of a glass-forming monomer at low temperatures has been studied. The water-particle phase content formed in a poly(diethylene glycol dimethacrylate) matrix was controlled by the addition of polyethylene glycol 600. The dispersed water-particle phase content in the matrix was estimated directly and by scanning electron microscopic observations. The release of potassium chloride from the matrix increased linearly with the square root of time. The water content of the matrix had an important effect on the release rate which increases roughly in proportion to water content. This effect can be attributed to the apparent increase of the rate of drug diffusion. (author)

  11. Stimuli-Responsive Materials for Controlled Release Applications

    KAUST Repository

    Li, Song

    2015-01-01

    The controlled release of therapeutics has been one of the major challenges for scientists and engineers during the past three decades. To address this outstanding problem, the design and fabrication of stimuli-responsive materials are pursued

  12. Electron gun controlled smart structure

    Science.gov (United States)

    Martin, Jeffrey W.; Main, John Alan; Redmond, James M.; Henson, Tammy D.; Watson, Robert D.

    2001-01-01

    Disclosed is a method and system for actively controlling the shape of a sheet of electroactive material; the system comprising: one or more electrodes attached to the frontside of the electroactive sheet; a charged particle generator, disposed so as to direct a beam of charged particles (e.g. electrons) onto the electrode; a conductive substrate attached to the backside of the sheet; and a power supply electrically connected to the conductive substrate; whereby the sheet changes its shape in response to an electric field created across the sheet by an accumulation of electric charge within the electrode(s), relative to a potential applied to the conductive substrate. Use of multiple electrodes distributed across on the frontside ensures a uniform distribution of the charge with a single point of e-beam incidence, thereby greatly simplifying the beam scanning algorithm and raster control electronics, and reducing the problems associated with "blooming". By placing a distribution of electrodes over the front surface of a piezoelectric film (or other electroactive material), this arrangement enables improved control over the distribution of surface electric charges (e.g. electrons) by creating uniform (and possibly different) charge distributions within each individual electrode. Removal or deposition of net electric charge can be affected by controlling the secondary electron yield through manipulation of the backside electric potential with the power supply. The system can be used for actively controlling the shape of space-based deployable optics, such as adaptive mirrors and inflatable antennae.

  13. Controlled release from drug microparticles via solventless dry-polymer coating.

    Science.gov (United States)

    Capece, Maxx; Barrows, Jason; Davé, Rajesh N

    2015-04-01

    A novel solvent-less dry-polymer coating process employing high-intensity vibrations avoiding the use of liquid plasticizers, solvents, binders, and heat treatments is utilized for the purpose of controlled release. The main hypothesis is that such process having highly controllable processing intensity and time may be effective for coating particularly fine particles, 100 μm and smaller via exploiting particle interactions between polymers and substrates in the dry state, while avoiding breakage yet achieving conformal coating. The method utilizes vibratory mixing to first layer micronized polymer onto active pharmaceutical ingredient (API) particles by virtue of van der Waals forces and to subsequently mechanically deform the polymer into a continuous film. As a practical example, ascorbic acid and ibuprofen microparticles, 50-500 μm, are coated with the polymers polyethylene wax or carnauba wax, a generally recognized as safe material, resulting in controlled release on the order of seconds to hours. As a novelty, models are utilized to describe the coating layer thickness and the controlled-release behavior of the API, which occurs because of a diffusion-based mechanism. Such modeling would allow the design and control of the coating process with application for the controlled release of microparticles, particularly those less than 100 μm, which are difficult to coat by conventional solvent coating methods. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  14. Use of fibrin sealants for the localized, controlled release of cefazolin

    Science.gov (United States)

    Tredwell, Stephen; Jackson, John K.; Hamilton, Donald; Lee, Vivian; Burt, Helen M.

    2006-01-01

    Background Fibrin sealants are used increasingly in surgery to reduce bleeding and improve wound healing. They have great potential as biocompatible, biodegradable drug delivery systems, because the sealant may adhere to the target tissue and allow controlled release of the drug over an extended period. We investigated the encapsulation, stability and controlled release of erythromycin and cefazolin from Beriplast fibrin sealants (Aventis Behring Canada). Methods Drug-loaded clots were cast in glass vials and allowed to set. We observed the clots for drug precipitation and aggregation, and we assessed the effect of drug encapsulation on clot strength. Drug stability and release from the clots in phosphate buffered saline (PBS) was quantified by ultraviolet and visible violet absorbance spectroscopy and high-performance liquid chromatography. Results Erythromycin was found to release slowly from the fibrin clots over the first 2 hours but then degrade rapidly. Cefazolin was found to be very stable in clots in PBS (97% stable at 2 d and 93% stable at 5 d). The drug released in a controlled manner over 2 days, with most being released during the first day. The dose of drug released could be varied by changing the amount placed in the thrombin solution. Clot thickness had no effect on the rate of cefazolin release. Conclusion Overall, the 2-day release profile and the excellent stability of the drug suggest that cefazolin-loaded fibrin sealants may offer an effective route of postoperative antibiotic delivery. PMID:17152573

  15. Improvement of waste release control in French NPP

    International Nuclear Information System (INIS)

    Samson, T.; Lucquin, E.; Dupin, M.; Florence, D.; Grisot, M.

    2002-01-01

    The new waste release control in French NPP is more restrictive than the old one and needs heavy investment to bring plants to compliance with it. The great evolutions are a chemical follow up on more chemicals with a higher measurement frequency and with lower maximum concentrations and a specific measurement of carbon 14. Regarding radioactive releases, a new counting has been settled and activity of carbon 14 release is now measured and no longer calculated. The evolution of the French regulation leads to develop specific procedures and analytical techniques in chemistry and in radiochemistry (UV spectrometric methods, carbon 14 measurements,..) EDF NPP operators have launched a voluntarist process to reduce their releases since the beginning and before the evolution of the regulation. EDF priorities in terms of environment care lead henceforth to implement a global optimisation of the impact for a better control of releases. The new regulation will help EDF to reach its goals because it covers all the aspects in one administrative document: it is seen as a real simplification and a clarification towards public. In addition, this new regulation fits in with international practices which will allow an easier comparison of results between EDF and foreign NPP. These big environmental concerns lead EDF to create a national dedicated laboratory (LAMEN) in charge of developing specific measurement procedures to be implemented either by NPP or by sub-contractor laboratories. (authors)

  16. Improvement of waste release control in French NPP

    Energy Technology Data Exchange (ETDEWEB)

    Samson, T.; Lucquin, E.; Dupin, M. [EDF/GDL (France); Florence, D. [EDF/GENV (France); Grisot, M. [EDF/CNPE Saint Laurent (France)

    2002-07-01

    The new waste release control in French NPP is more restrictive than the old one and needs heavy investment to bring plants to compliance with it. The great evolutions are a chemical follow up on more chemicals with a higher measurement frequency and with lower maximum concentrations and a specific measurement of carbon 14. Regarding radioactive releases, a new counting has been settled and activity of carbon 14 release is now measured and no longer calculated. The evolution of the French regulation leads to develop specific procedures and analytical techniques in chemistry and in radiochemistry (UV spectrometric methods, carbon 14 measurements,..) EDF NPP operators have launched a voluntarist process to reduce their releases since the beginning and before the evolution of the regulation. EDF priorities in terms of environment care lead henceforth to implement a global optimisation of the impact for a better control of releases. The new regulation will help EDF to reach its goals because it covers all the aspects in one administrative document: it is seen as a real simplification and a clarification towards public. In addition, this new regulation fits in with international practices which will allow an easier comparison of results between EDF and foreign NPP. These big environmental concerns lead EDF to create a national dedicated laboratory (LAMEN) in charge of developing specific measurement procedures to be implemented either by NPP or by sub-contractor laboratories. (authors)

  17. Polyvinyl alcohol composite nanofibres containing conjugated levofloxacin-chitosan for controlled drug release

    International Nuclear Information System (INIS)

    Jalvandi, Javid; White, Max; Gao, Yuan; Truong, Yen Bach; Padhye, Rajiv; Kyratzis, Ilias Louis

    2017-01-01

    A range of biodegradable drug-nanofibres composite mats have been reported as drug delivery systems. However, their main disadvantage is the rapid release of the drug immediately after application. This paper reports an improved system based on the incorporation of drug conjugated-chitosan into polyvinyl alcohol (PVA) nanofibers. The results showed that controlled release of levofloxacin (LVF) could be achieved by covalently binding LVF to low molecular weight chitosan (CS) via a cleavable amide bond and then blending the conjugated CS with polyvinyl alcohol (PVA) nanofibres prior to electrospinning. PVA/LVF and PVA-CS/LVF nanofibres were fabricated as controls. The conjugated CS-LVF was characterized by FTIR, DSC, TGA and 1 H NMR. Scanning electron microscopy (SEM) showed that the blended CS-PVA nanofibres had a reduced fibre diameter compared to the controls. Drug release profiles showed that burst release was decreased from 90% in the control PVA/LVF electrospun mats to 27% in the PVA/conjugated CS-LVF mats after 8 h in phosphate buffer at 37 °C. This slower release is due to the cleavable bond between LVF and CS that slowly hydrolysed over time at neutral pH. The results indicate that conjugation of the drug to the polymer backbone is an effective way of minimizing burst release behaviour and achieving sustained release of the drug, LVF. - Highlights: • A novel drug delivery system for controlled release of drug was designed. • Composite PVA/conjugated CS-LVF nanofibres was fabricated by electrospinning. • Conjugated chitosan and composite nanofibres were characterized by various techniques. • Release profiles of drug were significantly improved in composite nanofibres containing drug conjugated chitosan.

  18. Polyvinyl alcohol composite nanofibres containing conjugated levofloxacin-chitosan for controlled drug release

    Energy Technology Data Exchange (ETDEWEB)

    Jalvandi, Javid, E-mail: Javid.jlv@gmail.com [CSIRO, Manufacturing Flagship, Bayview Ave, Clayton, Victoria 3168 (Australia); School of Fashion and Textiles, College of Design and Social Context, RMIT University, 25 Dawson Street, Brunswick, Victoria 3056 (Australia); White, Max, E-mail: tamrak@bigpond.com [School of Fashion and Textiles, College of Design and Social Context, RMIT University, 25 Dawson Street, Brunswick, Victoria 3056 (Australia); Gao, Yuan, E-mail: Yuan.Gao@csiro.au [CSIRO, Manufacturing Flagship, Bayview Ave, Clayton, Victoria 3168 (Australia); Truong, Yen Bach, E-mail: Yen.truong@csiro.au [CSIRO, Manufacturing Flagship, Bayview Ave, Clayton, Victoria 3168 (Australia); Padhye, Rajiv, E-mail: rajiv.padhye@rmit.edu.au [School of Fashion and Textiles, College of Design and Social Context, RMIT University, 25 Dawson Street, Brunswick, Victoria 3056 (Australia); Kyratzis, Ilias Louis, E-mail: Louis.kyratzis@csiro.au [CSIRO, Manufacturing Flagship, Bayview Ave, Clayton, Victoria 3168 (Australia)

    2017-04-01

    A range of biodegradable drug-nanofibres composite mats have been reported as drug delivery systems. However, their main disadvantage is the rapid release of the drug immediately after application. This paper reports an improved system based on the incorporation of drug conjugated-chitosan into polyvinyl alcohol (PVA) nanofibers. The results showed that controlled release of levofloxacin (LVF) could be achieved by covalently binding LVF to low molecular weight chitosan (CS) via a cleavable amide bond and then blending the conjugated CS with polyvinyl alcohol (PVA) nanofibres prior to electrospinning. PVA/LVF and PVA-CS/LVF nanofibres were fabricated as controls. The conjugated CS-LVF was characterized by FTIR, DSC, TGA and {sup 1}H NMR. Scanning electron microscopy (SEM) showed that the blended CS-PVA nanofibres had a reduced fibre diameter compared to the controls. Drug release profiles showed that burst release was decreased from 90% in the control PVA/LVF electrospun mats to 27% in the PVA/conjugated CS-LVF mats after 8 h in phosphate buffer at 37 °C. This slower release is due to the cleavable bond between LVF and CS that slowly hydrolysed over time at neutral pH. The results indicate that conjugation of the drug to the polymer backbone is an effective way of minimizing burst release behaviour and achieving sustained release of the drug, LVF. - Highlights: • A novel drug delivery system for controlled release of drug was designed. • Composite PVA/conjugated CS-LVF nanofibres was fabricated by electrospinning. • Conjugated chitosan and composite nanofibres were characterized by various techniques. • Release profiles of drug were significantly improved in composite nanofibres containing drug conjugated chitosan.

  19. Controlled drug release from bifunctionalized mesoporous silica

    Science.gov (United States)

    Xu, Wujun; Gao, Qiang; Xu, Yao; Wu, Dong; Sun, Yuhan; Shen, Wanling; Deng, Feng

    2008-10-01

    Serial of trimethylsilyl-carboxyl bifunctionalized SBA-15 (TMS/COOH/SBA-15) have been studied as carriers for controlled release of drug famotidine (Famo). To load Famo with large capacity, SBA-15 with high content of carboxyl groups was successfully synthesized by one-pot synthesis under the assistance of KCl. The mesostructure of carboxyl functionalized SBA-15 (COOH/SBA-15) could still be kept even though the content of carboxyl groups was up to 57.2%. Increasing carboxyl content could effectively enhance the loading capacity of Famo. Compared with pure SBA-15, into which Famo could be hardly adsorbed, the largest drug loading capacity of COOH/SBA-15 could achieve 396.9 mg/g. The release of Famo from mesoporous silica was studied in simulated intestine fluid (SIF, pH=7.4). For COOH/SBA-15, the release rate of Famo decreased with narrowing pore size. After grafting TMS groups on the surface of COOH/SBA-15 with hexamethyldisilazane, the release of Famo was greatly delayed with the increasing content of TMS groups.

  20. Controlled antiseptic release by alginate polymer films and beads.

    Science.gov (United States)

    Liakos, Ioannis; Rizzello, Loris; Bayer, Ilker S; Pompa, Pier Paolo; Cingolani, Roberto; Athanassiou, Athanassia

    2013-01-30

    Biodegradable polymeric materials based on blending aqueous dispersions of natural polymer sodium alginate (NaAlg) and povidone iodine (PVPI) complex, which allow controlled antiseptic release, are presented. The developed materials are either free standing NaAlg films or Ca(2+)-cross-linked alginate beads, which properly combined with PVPI demonstrate antibacterial and antifungal activity, suitable for therapeutic applications, such as wound dressing. Glycerol was used as the plasticizing agent. Film morphology was studied by optical and atomic force microscopy. It was found that PVPI complex forms well dispersed circular micro-domains within the NaAlg matrix. The beads were fabricated by drop-wise immersion of NaAlg/PVPI/glycerol solutions into aqueous calcium chloride solutions to form calcium alginate beads encapsulating PVPI solution (CaAlg/PVPI). Controlled release of PVPI was possible when the composite films and beads were brought into direct contact with water or with moist media. Bactericidal and fungicidal properties of the materials were tested against Escherichia coli bacteria and Candida albicans fungi. The results indicated very efficient antibacterial and antifungal activity within 48 h. Controlled release of PVPI into open wounds is highly desired in clinical applications to avoid toxic doses of iodine absorption by the wound. A wide variety of applications are envisioned such as external and internal wound dressings with controlled antiseptic release, hygienic and protective packaging films for medical devices, and polymer beads as water disinfectants. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. HABIT, Toxic and Radioactive Release Hazards in Reactor Control Room

    International Nuclear Information System (INIS)

    Stage, S.A.

    2005-01-01

    1 - Description of program or function: HABIT is a package of computer codes designed to be used for the evaluation of control room habitability in the event of an accidental release of toxic chemicals or radioactive materials. 2 - Methods: Given information about the design of a nuclear power plant, a scenario for the release of toxic or radionuclides, and information about the air flows and protection systems of the control room, HABIT can be used to estimate the chemical exposure or radiological dose to control room personnel

  2. Stimuli responsive nanomaterials for controlled release applications

    KAUST Repository

    Li, Song; Li, Wengang; Khashab, Niveen M.

    2012-01-01

    applications. Stimuli-responsive nanomaterials guarantee the controlled release of cargo to a given location, at a specific time, and with an accurate amount. In this review, we have combined the major stimuli that are currently used to achieve the ultimate

  3. Sintering of wax for controlling release from pellets

    OpenAIRE

    Singh, Reena; Poddar, S. S.; Chivate, Amit

    2007-01-01

    The purpose of the present study was to investigate incorporation of hydrophobic (ie, waxy) material into pellets using a thermal sintering technique and to evaluate the pellets in vitro for controlled release. Pellets prepared by extrusion-spheronization technology were formulated with a water-soluble drug, microcrystalline cellulose, and carnauba wax. Powdered carnauba wax (4%–20%) prepared by grinding or by emulsification was studied with an attempt to retard the drug release. The inclusio...

  4. Electroactive polymer (EAP) actuators for future humanlike robots

    Science.gov (United States)

    Bar-Cohen, Yoseph

    2009-03-01

    Human-like robots are increasingly becoming an engineering reality thanks to recent technology advances. These robots, which are inspired greatly by science fiction, were originated from the desire to reproduce the human appearance, functions and intelligence and they may become our household appliance or even companion. The development of such robots is greatly supported by emerging biologically inspired technologies. Potentially, electroactive polymer (EAP) materials are offering actuation capabilities that allow emulating the action of our natural muscles for making such machines perform lifelike. There are many technical issues related to making such robots including the need for EAP materials that can operate as effective actuators. Beside the technology challenges these robots also raise concerns that need to be addressed prior to forming super capable robots. These include the need to prevent accidents, deliberate harm, or their use in crimes. In this paper, the potential EAP actuators and the challenges that these robots may pose will be reviewed.

  5. Electroactive Polymer (EAP) Actuators for Future Humanlike Robots

    Science.gov (United States)

    Bar-Cohen, Yoseph

    2009-01-01

    Human-like robots are increasingly becoming an engineering reality thanks to recent technology advances. These robots, which are inspired greatly by science fiction, were originated from the desire to reproduce the human appearance, functions and intelligence and they may become our household appliance or even companion. The development of such robots is greatly supported by emerging biologically inspired technologies. Potentially, electroactive polymer (EAP) materials are offering actuation capabilities that allow emulating the action of our natural muscles for making such machines perform lifelike. There are many technical issues related to making such robots including the need for EAP materials that can operate as effective actuators. Beside the technology challenges these robots also raise concerns that need to be addressed prior to forming super capable robots. These include the need to prevent accidents, deliberate harm, or their use in crimes. In this paper, the potential EAP actuators and the challenges that these robots may pose will be reviewed.

  6. Magnetic molecularly imprinted polymer for aspirin recognition and controlled release

    Energy Technology Data Exchange (ETDEWEB)

    Kan Xianwen; Geng Zhirong; Zhao Yao; Wang Zhilin; Zhu Junjie [State Key Laboratory of Coordination Chemistry, MOE Key Lab of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 22 Hankou Road, Nanjing 210093 (China)], E-mail: wangzl@nju.edu.cn, E-mail: jjzhu@nju.edu.cn

    2009-04-22

    Core-shell structural magnetic molecularly imprinted polymers (magnetic MIPs) with combined properties of molecular recognition and controlled release were prepared and characterized. Magnetic MIPs were synthesized by the co-polymerization of methacrylic acid (MAA) and trimethylolpropane trimethacrylate (TRIM) around aspirin (ASP) at the surface of double-bond-functionalized Fe{sub 3}O{sub 4} nanoparticles in chloroform. The obtained spherical magnetic MIPs with diameters of about 500 nm had obvious superparamagnetism and could be separated quickly by an external magnetic field. Binding experiments were carried out to evaluate the properties of magnetic MIPs and magnetic non-molecularly imprinted polymers (magnetic NIPs). The results demonstrated that the magnetic MIPs had high adsorption capacity and selectivity to ASP. Moreover, release profiles and release rate of ASP from the ASP-loaded magnetic MIPs indicated that the magnetic MIPs also had potential applications in drug controlled release.

  7. Magnetic molecularly imprinted polymer for aspirin recognition and controlled release

    International Nuclear Information System (INIS)

    Kan Xianwen; Geng Zhirong; Zhao Yao; Wang Zhilin; Zhu Junjie

    2009-01-01

    Core-shell structural magnetic molecularly imprinted polymers (magnetic MIPs) with combined properties of molecular recognition and controlled release were prepared and characterized. Magnetic MIPs were synthesized by the co-polymerization of methacrylic acid (MAA) and trimethylolpropane trimethacrylate (TRIM) around aspirin (ASP) at the surface of double-bond-functionalized Fe 3 O 4 nanoparticles in chloroform. The obtained spherical magnetic MIPs with diameters of about 500 nm had obvious superparamagnetism and could be separated quickly by an external magnetic field. Binding experiments were carried out to evaluate the properties of magnetic MIPs and magnetic non-molecularly imprinted polymers (magnetic NIPs). The results demonstrated that the magnetic MIPs had high adsorption capacity and selectivity to ASP. Moreover, release profiles and release rate of ASP from the ASP-loaded magnetic MIPs indicated that the magnetic MIPs also had potential applications in drug controlled release.

  8. FERLENT - a controlled release fertilizer produced from a polymer material

    International Nuclear Information System (INIS)

    Gonzalez, Mayra; Arces, Milagros; Cuesta, Ernesto; Corredera, Pilar; Sardina, Carmen; Rieumont, Jacques; Quintana, Patricia; Bartolo, Pascual; Guenther, Bluma

    2011-01-01

    The possibility to use release controlled fertilizers in the agriculture of the tropical countries is more important than in the agriculture of the countries of the template regions. In this context, this work purpose the development of a new Fertilizer of Controlled Release named FERLENT, which was obtained starting from a polymeric material, under controlled conditions which allowed to corroborate the adjustment of the synthesis parameters under the modulate of nutrients liberation. It was characterized by, Scanning Microscopy Electron (SEM), Thermogravimetric analysis (TGA), Nuclear Magnetic Resonance (NMR) and infrared spectroscopy (FTIR). (author)

  9. Application of tumbling melt granulation (TMG) method to prepare controlled-release fine granules.

    Science.gov (United States)

    Maejima, T; Kubo, M; Osawa, T; Nakajima, K; Kobayashi, M

    1998-03-01

    The tumbling melt granulation (TMG) method was applied to prepare controlled-release fine granules of diltiazem hydrochloride (DH). The entire process, from the preparation of the cores by the adherence of DH to the sucrose crystal to the subsequent coating of the controlled-release layer, was performed without using any solvent. A mixture of meltable material, talc, and ethylcellulose was used for the controlled-release layer and controlled-release fine granules approximately 400 microns in diameter were obtained with excellent producibility. The dissolution rate of DH from these fine granules was similar to that of a once-a-day dosage form obtained in the market; further, the dependency of the dissolution profile on pH of the media was less. Thus, it was concluded that this TMG method was very useful for preparing not only controlled-release beads of granule size (usually 500 to 1400 microns) but also fine granules.

  10. Possibility of cellulose-based electro-active paper energy scavenging transducer.

    Science.gov (United States)

    Abas, Zafar; Kim, Heung Soo; Zhai, Lindong; Kim, Jaehwan; Kim, Joo Hyung

    2014-10-01

    In this paper, a cellulose-based Electro-Active Paper (EAPap) energy scavenging transducer is presented. Cellulose is proven as a smart material, and exhibits piezoelectric effect. Specimens were prepared by coating gold electrodes on both sides of cellulose film. The fabricated specimens were tested by a base excited aluminum cantilever beam at resonant frequency. Different tests were performed with single and multiple parallel connected electrodes coated on the cellulose film. A maximum of 131 mV output voltage was measured, when three electrodes were connected in parallel. It was observed that voltage output increases significantly with the area of electrodes. From these results, it can be concluded that the piezoelectricity of cellulose-based EAPap can be used in energy transduction application.

  11. Bioadhesive Controlled Release Clotrimazole Vaginal Tablets | Bhat ...

    African Journals Online (AJOL)

    Conclusion: This study indicates the possible use of suitable mixtures of natural and semi-synthetic cellulosic polymers for the preparation of clotrimazole mucoadhesive tablets for application as a vaginal controlled delivery system. Keywords: Clotrimazole, Swelling, Cellulosic polymers, Guar gum, Bioadhesion, Release ...

  12. Controlling Release of Integral Lipid Nanoparticles Based on Osmotic Pump Technology.

    Science.gov (United States)

    Tian, Zhiqiang; Yu, Qin; Xie, Yunchang; Li, Fengqian; Lu, Yi; Dong, Xiaochun; Zhao, Weili; Qi, Jianping; Wu, Wei

    2016-08-01

    To achieve controlled release of integral nanoparticles by the osmotic pump strategy using nanostructured lipid carriers (NLCs) as model nanoparticles. NLCs was prepared by a hot-homogenization method, transformed into powder by lyophilization, and formulated into osmotic pump tablets (OPTs). Release of integral NLCs was visualized by live imaging after labeling with a water-quenching fluorescent probe. Effects of formulation variables on in vitro release characteristics were evaluated by measuring the model drug fenofibrate. Pharmacokinetics were studied in beagle dogs using the core tablet and a micronized fenofibrate formulation as references. NLCs are released through the release orifices of the OPTs as integral nanoparticles. Near zero-order kinetics can be achieved by optimizing the influencing variables. After oral administration, decreased C max and steady drug levels for as long as over 24 h are observed. NLC-OPTs show an oral bioavailability of the model drug fenofibrate similar to that of the core tablets, which is about 1.75 folds that of a fast-release formulation. Controlled release of integral NLCs is achieved by the osmotic pump strategy.

  13. Magneto- to electroactive transmutation of spin waves in ErMnO3.

    Science.gov (United States)

    Chaix, L; de Brion, S; Petit, S; Ballou, R; Regnault, L-P; Ollivier, J; Brubach, J-B; Roy, P; Debray, J; Lejay, P; Cano, A; Ressouche, E; Simonet, V

    2014-04-04

    The low-energy dynamical properties of the multiferroic hexagonal perovskite ErMnO3 have been studied by inelastic neutron scattering as well as terahertz and far infrared spectroscopies on a synchrotron source. From these complementary techniques, we have determined the magnon and crystal field spectra and identified a zone center magnon excitable only by the electric field of an electromagnetic wave. Using a comparison with the isostructural YMnO3 compound and crystal field calculations, we propose that this dynamical magnetoelectric process is due to the hybridization of a magnon with an electroactive crystal field transition.

  14. Control of accidental releases of hydrogen selenide in vented storage cabinets

    Science.gov (United States)

    Fthenakis, V. M.; Moskowitz, P. D.; Sproull, R. D.

    1988-07-01

    Highly toxic hydrogen selenide and hydrogen sulfide gases are used in the production of copper-indium-diselenide photovoltaic cells by reactive sputtering. In the event of an accident, these gases may be released to the atmosphere and pose hazards to public and occupational safety and health. This paper outlines an approach for designing systems for the control of these releases given the uncertainty in release conditions and lack of data on the chemical systems involved. Accidental releases of these gases in storage cabinets can be controlled by either a venturi and packed-bed scrubber and carbon adsorption bed, or containment scrubbing equipment followed by carbon adsorption. These systems can effectively reduce toxic gas emissions to levels needed to protect public health. The costs of these controls (˜0.012/Wp) are samll in comparison with current (˜6/Wp) and projected (˜I/Wp) production costs.

  15. Organosilane functionalization of halloysite nanotubes for enhanced loading and controlled release

    International Nuclear Information System (INIS)

    Yuan Peng; Southon, Peter D; Kepert, Cameron J; Liu Zongwen

    2012-01-01

    The surfaces of naturally occurring halloysite nanotubes were functionalized with γ-aminopropyltriethoxysilane (APTES), which was found to have a substantial effect on the loading and subsequent release of a model dye molecule. APTES was mostly anchored at the internal lumen surface of halloysite through covalent grafting, forming a functionalized surface covered by aminopropyl groups. The dye loading of the functionalized halloysite was 32% greater than that of the unmodified sample, and the release from the functionalized halloysite was dramatically prolonged as compared to that from the unmodified one. Dye release was prolonged at low pH and the release at pH 3.5 was approximately three times slower than that at pH 10.0. These results demonstrate that organosilane functionalization makes pH an external trigger for controlling the loading of guest on halloysite and the subsequent controlled release. (paper)

  16. Organosilane functionalization of halloysite nanotubes for enhanced loading and controlled release.

    Science.gov (United States)

    Yuan, Peng; Southon, Peter D; Liu, Zongwen; Kepert, Cameron J

    2012-09-21

    The surfaces of naturally occurring halloysite nanotubes were functionalized with γ-aminopropyltriethoxysilane (APTES), which was found to have a substantial effect on the loading and subsequent release of a model dye molecule. APTES was mostly anchored at the internal lumen surface of halloysite through covalent grafting, forming a functionalized surface covered by aminopropyl groups. The dye loading of the functionalized halloysite was 32% greater than that of the unmodified sample, and the release from the functionalized halloysite was dramatically prolonged as compared to that from the unmodified one. Dye release was prolonged at low pH and the release at pH 3.5 was approximately three times slower than that at pH 10.0. These results demonstrate that organosilane functionalization makes pH an external trigger for controlling the loading of guest on halloysite and the subsequent controlled release.

  17. Electroactive Phase Induced Bi4Ti3O12-Poly(Vinylidene Difluoride) Composites with Improved Dielectric Properties

    Science.gov (United States)

    Bhardwaj, Sumit; Paul, Joginder; Chand, Subhash; Raina, K. K.; Kumar, Ravi

    2015-10-01

    Lead-free ceramic-polymer composite films containing Bi4Ti3O12 (BIT) nanocrystals as the active phase and poly(vinylidene difluoride) as the passive matrix were synthesized by spin coating. The films' structural, morphological, and dielectric properties were systemically investigated by varying the weight fraction of BIT. Formation of electroactive β and γ phases were strongly affected by the presence of BIT nanocrystals. Analysis was performed by Fourier-transform infrared and Raman spectroscopy. Morphological studies confirmed the homogeneous dispersion of BIT particles within the polymer matrix. The composite films had dielectric constants as high as 52.8 and low dielectric loss of 0.1 at 100 Hz when the BIT content was 10 wt.%. We suggest that the enhanced electroactive phase content of the polymer matrix and interfacial polarization may contribute to the improved dielectric performance of these composite films. Dielectric modulus analysis was performed to enable understanding of the dielectric relaxation process. Non-Debye-type relaxation behavior was observed for the composite films at high temperature.

  18. A study of metalized electrode self-clearing in electroactive polymer (EAP) based actuators

    Science.gov (United States)

    Ahmed, Saad; Ounaies, Zoubeida

    2016-04-01

    Electroactive polymer (EAP) based technologies have shown promise in areas such as artificial muscles, actuator, aerospace, medical and soft robotics. Still challenges remain such as low induced forces and defects-driven electrical breakdown, which impede the practical implementation of this technology. Multilayered or stacked configuration can address the low induced force issue whereas self-clearing can be a technique to improve breakdown limit of EAP based actuators. Self-clearing refers to the partial local breakdown of dielectric medium due to the presence of impurities, which in turn results in the evaporation of some of the metalized electrode. After this evaporation, the impurity is cleared and any current path would be safely cut off, which means the actuator continues to perform. It is a widely studied concept in the capacitor community, while it has not been studied much for EAP technologies. In this paper we report a systematic approach to precondition a silver-metalized electroactive polymer (EAP), more specifically P(VDF-TrFE-CTFE) terpolymer, using self-clearing concept. First, we show improvement in the dielectric breakdown strength of EAP based unimorph actuators after pre-clearing the impurities using low electric field (lower than dielectric breakdown of the terpolymer). Inspired by this improvement, we used Weibull statistics to systematically estimate the self-clearing/ preconditioning field needed to clear the defects. Then electrical breakdown experiments are conducted with and without preconditioning the samples to investigate its effect on the breakdown strength of the sample.

  19. Effect of Nisin's Controlled Release on Microbial Growth as Modeled for Micrococcus luteus.

    Science.gov (United States)

    Balasubramanian, Aishwarya; Lee, Dong Sun; Chikindas, Michael L; Yam, Kit L

    2011-06-01

    The need for safe food products has motivated food scientists and industry to find novel technologies for antimicrobial delivery for improving food safety and quality. Controlled release packaging is a novel technology that uses the package to deliver antimicrobials in a controlled manner and sustain antimicrobial stress on the targeted microorganism over the required shelf life. This work studied the effect of controlled release of nisin to inhibit growth of Micrococcus luteus (a model microorganism) using a computerized syringe pump system to mimic the release of nisin from packaging films which was characterized by an initially fast rate and a slower rate as time progressed. The results show that controlled release of nisin was strikingly more effective than instantly added ("formulated") nisin. While instant addition experiments achieved microbial inhibition only at the beginning, controlled release experiments achieved complete microbial inhibition for a longer time, even when as little as 15% of the amount of nisin was used as compared to instant addition.

  20. Sintering of wax for controlling release from pellets.

    Science.gov (United States)

    Singh, Reena; Poddar, S S; Chivate, Amit

    2007-09-14

    The purpose of the present study was to investigate incorporation of hydrophobic (ie, waxy) material into pellets using a thermal sintering technique and to evaluate the pellets in vitro for controlled release. Pellets prepared by extrusion-spheronization technology were formulated with a water-soluble drug, microcrystalline cellulose, and carnauba wax. Powdered carnauba wax (4%-20%) prepared by grinding or by emulsification was studied with an attempt to retard the drug release. The inclusion of ground or emulsified carnauba wax did not sustain the release of theophylline for more than 3 hours. Matrix pellets of theophylline prepared with various concentrations of carnauba wax were sintered thermally at various times and temperatures. In vitro drug release profiles indicated an increase in drug release retardation with increasing carnauba wax concentration. Pellets prepared with ground wax showed a higher standard deviation than did those prepared with emulsified wax. There was incomplete release at the end of 12 hours for pellets prepared with 20% ground or emulsified wax. The sintering temperature and duration were optimized to allow for a sustained release lasting at least 12 hours. The optimized temperature and duration were found to be 100 degrees C and 140 seconds, respectively. The sintered pellets had a higher hydrophobicity than did the unsintered pellets. Scanning electron micrographs indicated that the carnauba wax moved internally, thereby increasing the surface area of wax within the pellets.

  1. Method and apparatus for controlling accidental releases of tritium

    International Nuclear Information System (INIS)

    Galloway, T.R.

    1980-01-01

    An improvement in a tritium control system based on a catalytic oxidation reactor is provided wherein accidental releases of tritium into room air are controlled by flooding the catalytic oxidation reactor with hydrogen when the tritium concentration in the room air exceeds a specified limit. The sudden flooding with hydrogen heats the catalyst to a high temperature within seconds, thereby greatly increasing the catalytic oxidation rate of tritium to tritiated water vapor. Thus, the catalyst is heated only when needed. In addition to the heating effect, the hydrogen flow also swamps the tritium and further reduces the tritium release

  2. Method and apparatus for controlling accidental releases of tritium

    Science.gov (United States)

    Galloway, Terry R. [Berkeley, CA

    1980-04-01

    An improvement in a tritium control system based on a catalytic oxidation reactor wherein accidental releases of tritium into room air are controlled by flooding the catalytic oxidation reactor with hydrogen when the tritium concentration in the room air exceeds a specified limit. The sudden flooding with hydrogen heats the catalyst to a high temperature within seconds, thereby greatly increasing the catalytic oxidation rate of tritium to tritiated water vapor. Thus, the catalyst is heated only when needed. In addition to the heating effect, the hydrogen flow also swamps the tritium and further reduces the tritium release.

  3. Role of various natural, synthetic and semi-synthetic polymers on drug release kinetics of losartan potassium oral controlled release tablets.

    Science.gov (United States)

    Jayasree, J; Sivaneswari, S; Hemalatha, G; Preethi, N; Mounika, B; Murthy, S Vasudeva

    2014-10-01

    The objective of the present work was to formulate and to characterize controlled release matrix tablets of losartan potassium in order to improve bioavailability and to minimize the frequency of administration and increase the patient compliance. Losartan potassium controlled release matrix tablets were prepared by direct compression technique by the use of different natural, synthetic and semisynthetic polymers such as gum copal, gum acacia, hydroxypropyl methyl cellulose K100 (HPMC K100), eudragit RL 100 and carboxy methyl ethyl cellulose (CMEC) individually and also in combination. Studies were carried out to study the influence of type of polymer on drug release rate. All the formulations were subjected to physiochemical characterization such as weight variation, hardness, thickness, friability, drug content, and swelling index. In vitro dissolution studies were carried out simulated gastric fluid (pH 1.2) for first 2 h and followed by simulated intestinal fluid (pH 6.8) up to 24 h, and obtained dissolution data were fitted to in vitro release kinetic equations in order to know the order of kinetics and mechanism of drug release. Results of physiochemical characterization of losartan potassium matrix tablets were within acceptable limits. Formulation containing HPMC K100 and CMEC achieved the desired drug release profile up to 24 h followed zero order kinetics, release pattern dominated by Korsmeyer - Peppas model and mechanism of drug release by nonfickian diffusion. The good correlation obtained from Hixson-Crowell model indicates that changes in surface area of the tablet also influences the drug release. Based on the results, losartan potassium controlled release matrix tablets prepared by employing HPMC K100 and CMEC can attain the desired drug release up to 24 h, which results in maintaining steady state concentration and improving bioavailability.

  4. Effect of non-electroactive additives on the early stage pyrrole electropolymerization on indium tin oxide electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Castro-Beltran, A. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ave. Pedro de Alba s/n, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Centro de Innovación Investigación y Desarrollo en Ingeniería y Tecnología (CIIDIT), Universidad Autónoma de Nuevo León, PIIT-Monterrey C.P. 66600 Apodaca, N.L. (Mexico); Dominguez, C.; Bahena-Uribe, D. [Centro Investigación en Ingeniería y Ciencias Aplicadas (CIICAp), Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, C.P. 62209 Cuernavaca, Mor. (Mexico); Sepulveda-Guzman, S., E-mail: selene.sepulvedagz@uanl.edu.mx [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ave. Pedro de Alba s/n, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Centro de Innovación Investigación y Desarrollo en Ingeniería y Tecnología (CIIDIT), Universidad Autónoma de Nuevo León, PIIT-Monterrey C.P. 66600 Apodaca, N.L. (Mexico); Cruz-Silva, R. [Research Center for Exotic NanoCarbon, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan)

    2014-09-01

    The use of non-electroactive additives during electrodeposition of conducting polymers has long been used to modify the properties of deposited films. These additives can improve the adhesion, and not only change the morphology and deposition rate but also modify the chemical composition of the electrodeposited polymer. Several compounds have been used to modify deposition of polypyrrole; however, there is no systematic study of these compounds. In this work, we comparatively studied several water soluble chemical compounds, a cationic polymer, an anionic polymer, a cationic surfactant, and an anionic surfactant during potentiostatic electrodeposition of polypyrrole. In order to study the effect of these compounds on the interface, where the electrochemical polymerization takes place, we used electrochemical impedance spectroscopy. The morphology during the initial stage of growth was studied by atomic force microscopy, whereas the resulting polypyrrole films were observed by scanning electron microscopy. - Highlights: • Early-stage polymerization polypyrrole particles on indium tin oxide (ITO). • Anionic additives promote pyrrole oxidation and polypyrrole film growth on ITO. • Cationic polyelectrolyte promotes adhesion between ITO and polypyrrole film. • Non-electroactive additives strongly influence polypyrrole nucleation on ITO.

  5. 3D Printing of Aniline Tetramer-Grafted-Polyethylenimine and Pluronic F127 Composites for Electroactive Scaffolds.

    Science.gov (United States)

    Dong, Shi-Lei; Han, Lu; Du, Cai-Xia; Wang, Xiao-Yu; Li, Lu-Hai; Wei, Yen

    2017-02-01

    Electroactive hydrogel scaffolds are fabricated by the 3D-printing technique using composites of 30% Pluronic F127 and aniline tetramer-grafted-polyethylenimine (AT-PEI) copolymers with various contents from 2.5% to 10%. The synthesized AT-PEI copolymers can self-assemble into nanoparticles with the diameter of ≈50 nm and display excellent electroactivity due to AT conjugation. The copolymers are then homogeneously distributed into 30% Pluronic F127 solution by virtue of the thermosensitivity of F127, denoted as F/AT-PEI composites. Macroscopic photographs of latticed scaffolds elucidate their excellent printability of F/AT-PEI hydrogels for the 3D-printing technique. The conductivities of the printed F/AT-PEI scaffolds are all higher than 2.0 × 10 -3 S cm -1 , which are significantly improved compared with that of F127 scaffold with only 0.94 × 10 -3 S cm -1 . Thus, the F/AT-PEI scaffolds can be considered as candidates for application in electrical stimulation of tissue regeneration such as repair of muscle and cardiac nerve tissue. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Microfluidic synthesis of microfibers for magnetic-responsive controlled drug release and cell culture.

    Directory of Open Access Journals (Sweden)

    Yung-Sheng Lin

    Full Text Available This study demonstrated the fabrication of alginate microfibers using a modular microfluidic system for magnetic-responsive controlled drug release and cell culture. A novel two-dimensional fluid-focusing technique with multi-inlets and junctions was used to spatiotemporally control the continuous laminar flow of alginate solutions. The diameter of the manufactured microfibers, which ranged from 211 µm to 364 µm, could be well controlled by changing the flow rate of the continuous phase. While the model drug, diclofenac, was encapsulated into microfibers, the drug release profile exhibited the characteristic of a proper and steady release. Furthermore, the diclofenac release kinetics from the magnetic iron oxide-loaded microfibers could be controlled externally, allowing for a rapid drug release by applying a magnetic force. In addition, the successful culture of glioblastoma multiforme cells in the microfibers demonstrated a good structural integrity and environment to grow cells that could be applied in drug screening for targeting cancer cells. The proposed microfluidic system has the advantages of ease of fabrication, simplicity, and a fast and low-cost process that is capable of generating functional microfibers with the potential for biomedical applications, such as drug controlled release and cell culture.

  7. A review of mathematical modeling and simulation of controlled-release fertilizers.

    Science.gov (United States)

    Irfan, Sayed Ameenuddin; Razali, Radzuan; KuShaari, KuZilati; Mansor, Nurlidia; Azeem, Babar; Ford Versypt, Ashlee N

    2018-02-10

    Nutrients released into soils from uncoated fertilizer granules are lost continuously due to volatilization, leaching, denitrification, and surface run-off. These issues have caused economic loss due to low nutrient absorption efficiency and environmental pollution due to hazardous emissions and water eutrophication. Controlled-release fertilizers (CRFs) can change the release kinetics of the fertilizer nutrients through an abatement strategy to offset these issues by providing the fertilizer content in synchrony with the metabolic needs of the plants. Parametric analysis of release characteristics of CRFs is of paramount importance for the design and development of new CRFs. However, the experimental approaches are not only time consuming, but they are also cumbersome and expensive. Scientists have introduced mathematical modeling techniques to predict the release of nutrients from the CRFs to elucidate fundamental understanding of the dynamics of the release processes and to design new CRFs in a shorter time and with relatively lower cost. This paper reviews and critically analyzes the latest developments in the mathematical modeling and simulation techniques that have been reported for the characteristics and mechanisms of nutrient release from CRFs. The scope of this review includes the modeling and simulations techniques used for coated, controlled-release fertilizers. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Controlled release of agrochemicals intercalated into montmorillonite interlayer space.

    Science.gov (United States)

    Wanyika, Harrison

    2014-01-01

    Periodic application of agrochemicals has led to high cost of production and serious environmental pollution. In this study, the ability of montmorillonite (MMT) clay to act as a controlled release carrier for model agrochemical molecules has been investigated. Urea was loaded into MMT by a simple immersion technique while loading of metalaxyl was achieved by a rotary evaporation method. The successful incorporation of the agrochemicals into the interlayer space of MMT was confirmed by several techniques, such as, significant expansion of the interlayer space, reduction of Barrett-Joyner-Halenda (BJH) pore volumes and Brunauer-Emmett-Teller (BET) surface areas, and appearance of urea and metalaxyl characteristic bands on the Fourier-transform infrared spectra of the urea loaded montmorillonite (UMMT) and metalaxyl loaded montmorillonite (RMMT) complexes. Controlled release of the trapped molecules from the matrix was done in water and in the soil. The results reveal slow and sustained release behaviour for UMMT for a period of 10 days in soil. For a period of 30 days, MMT delayed the release of metalaxyl in soil by more than 6 times. It is evident that MMT could be used to improve the efficiency of urea and metalaxyl delivery in the soil.

  9. Laser-activated nano-biomaterials for tissue repair and controlled drug release

    International Nuclear Information System (INIS)

    Matteini, P; Ratto, F; Rossi, F; Pini, R

    2014-01-01

    We present recent achievements of minimally invasive welding of biological tissue and controlled drug release based on laser-activated nano-biomaterials. In particular, we consider new advancements in the biomedical application of near-IR absorbing gold nano-chromophores as an original solution for the photothermal repair of surgical incisions and as nanotriggers of controlled drug release from hybrid biopolymer scaffolds. (laser biophotonics)

  10. MWCNTs-Reinforced Epoxidized Linseed Oil Plasticized Polylactic Acid Nanocomposite and Its Electroactive Shape Memory Behaviour

    OpenAIRE

    Alam, Javed; Alam, Manawwer; Raja, Mohan; Abduljaleel, Zainularifeen; Dass, Lawrence

    2014-01-01

    A novel electroactive shape memory polymer nanocomposite of epoxidized linseed oil plasticized polylactic acid and multi-walled carbon nanotubes (MWCNTs) was prepared by a combination of solution blending, solvent cast technique, and hydraulic hot press moulding. In this study, polylactic acid (PLA) was first plasticized by epoxidized linseed oil (ELO) in order to overcome the major limitations of PLA, such as high brittleness, low toughness, and low tensile elongation. Then, MWCNTs were inc...

  11. Chemical physics of electroactive materials: concluding remarks.

    Science.gov (United States)

    Rutland, Mark W

    2017-07-01

    It is an honour to be charged with providing the concluding remarks for a Faraday Discussion. As many have remarked before, it is nonetheless a prodigious task, and what follows is necessarily a personal, and probably perverse, view of a watershed event in the Chemical Physics of Electroactive materials. The spirit of the conference was captured in a single sentence during the meeting itself."It is the nexus between rheology, electrochemistry, colloid science and energy storage". The current scientific climate is increasingly dominated by a limited number of global challenges, and there is thus a tendency for research to resemble a football match played by 6 year olds, where everyone on the field chases the (funding) ball instead of playing to their "discipline". It is thus reassuring to see how the application of rigorous chemical physics is leading to ingenious new solutions for both energy storage and harvesting, via, for example, nanoactuation, electrowetting, ionic materials and nanoplasmonics. In fact, the same language of chemical physics allows seamless transition between applications as diverse as mechano-electric energy generation, active moisture transport and plasmonic shutters - even the origins of life were addressed in the context of electro-autocatalysis!

  12. Hydrophobic Drug-Loaded PEGylated Magnetic Liposomes for Drug-Controlled Release

    Science.gov (United States)

    Hardiansyah, Andri; Yang, Ming-Chien; Liu, Ting-Yu; Kuo, Chih-Yu; Huang, Li-Ying; Chan, Tzu-Yi

    2017-05-01

    Less targeted and limited solubility of hydrophobic-based drug are one of the serious obstacles in drug delivery system. Thus, new strategies to enhance the solubility of hydrophobic drug and controlled release behaviors would be developed. Herein, curcumin, a model of hydrophobic drug, has been loaded into PEGylated magnetic liposomes as a drug carrier platform for drug controlled release system. Inductive magnetic heating (hyperthermia)-stimulated drug release, in vitro cellular cytotoxicity assay of curcumin-loaded PEGylated magnetic liposomes and cellular internalization-induced by magnetic guidance would be investigated. The resultant of drug carriers could disperse homogeneously in aqueous solution, showing a superparamagnetic characteristic and could inductive magnetic heating with external high-frequency magnetic field (HFMF). In vitro curcumin release studies confirmed that the drug carriers exhibited no significant release at 37 °C, whereas exhibited rapid releasing at 45 °C. However, it would display enormous (three times higher) curcumin releasing under the HFMF exposure, compared with that without HFMF exposure at 45 °C. In vitro cytotoxicity test shows that curcumin-loaded PEGylated magnetic liposomes could efficiently kill MCF-7 cells in parallel with increasing curcumin concentration. Fluorescence microscopy observed that these drug carriers could internalize efficiently into the cellular compartment of MCF-7 cells. Thus, it would be anticipated that the novel hydrophobic drug-loaded PEGylated magnetic liposomes in combination with inductive magnetic heating are promising to apply in the combination of chemotherapy and thermotherapy for cancer therapy.

  13. Controlled release of ethylene via polymeric films for food packaging

    Science.gov (United States)

    Pisano, Roberto; Bazzano, Marco; Capozzi, Luigi Carlo; Ferri, Ada; Sangermano, Marco

    2015-12-01

    In modern fruit supply chain a common method to trigger ripening is to keep fruits inside special chambers and initiate the ripening process through administration of ethylene. Ethylene is usually administered through cylinders with inadequate control of its final concentration in the chamber. The aim of this study is the development of a new technology to accurately regulate ethylene concentration in the atmosphere where fruits are preserved: a polymeric film, containing an inclusion complex of α-cyclodextrin with ethylene, was developed. The complex was prepared by molecular encapsulation which allows the entrapment of ethylene into the cavity of α-cyclodextrin. After encapsulation, ethylene can be gradually released from the inclusion complex and its release rate can be regulated by temperature and humidity. The inclusion complex was dispersed into a thin polymeric film produced by UV-curing. This method was used because is solvent-free and involves low operating temperature; both conditions are necessary to prevent rapid release of ethylene from the film. The polymeric films were characterized with respect to thermal behaviour, crystalline structure and kinetics of ethylene release, showing that can effectively control the release of ethylene within confined volume.

  14. Electrochemically controlled release of anticancer drug methotrexate using nanostructured polypyrrole modified with cetylpyridinium: Release kinetics investigation

    International Nuclear Information System (INIS)

    Alizadeh, Naader; Shamaeli, Ehsan

    2014-01-01

    A new simple strategy for direct electrochemical incorporation of chemotherapeutic methotrexate (MTX) into conductive polypyrrole (PPy) has been suggested for an electrochemically controlled loading and release system. Electropolymerization of MTX doped polypyrrole yielded poor quality with low efficiency of doping, but a well-doped, nanostructure and increased capacity of drug loading (24.5 mg g −1 ) has been obtained in the presence of cetylpyridinium (CP) as a modifier. When CP was preloaded onto PPy, the hydrophobic surface of the PPy serves as a backbone to which the hydrophobic chain of the CP can be attached. Electrostatic interaction between cationic CP with anionic MTX and aromatic interaction between pyridinium head of CP with pyrimidine and pyrazine rings of MTX increases drug doping. Then release kinetics were investigated at various applied potentials and temperatures. Kinetics analysis based on Avrami's equation showed that the drug release was controlled and accelerated by increasing temperature and negative potential and sustained by increasing positive potential. At open circuit condition, the release parameter (n) represented a diffusive mechanism and at applying electrochemical potentials, a first-order mode. Activation energy parameters (E a , ΔG ≠ , ΔH ≠ and ΔS ≠ ) and half-life time (t 1/2 ) of drug release are also analyzed as a function of applied potential. The nanostructured polymer films (PPy/CP/MTX) were characterized by several techniques: scanning electron microscopy, Furrier transforms Infrared, UV-vis spectroscopy. Overall, our results demonstrate that the PPy/CP/MTX films, combined with electrical stimulation, permit a programmable release of MTX by altering the interaction strength between the PPy/CP and MTX

  15. Materials for Pharmaceutical Dosage Forms: Molecular Pharmaceutics and Controlled Release Drug Delivery Aspects

    Directory of Open Access Journals (Sweden)

    Patrick P. DeLuca

    2010-09-01

    Full Text Available Controlled release delivery is available for many routes of administration and offers many advantages (as microparticles and nanoparticles over immediate release delivery. These advantages include reduced dosing frequency, better therapeutic control, fewer side effects, and, consequently, these dosage forms are well accepted by patients. Advances in polymer material science, particle engineering design, manufacture, and nanotechnology have led the way to the introduction of several marketed controlled release products and several more are in pre-clinical and clinical development.

  16. Synthesis of new electroactive polymers by ion-exchange replacement of Mg(II) by 2H+ or Zn(II) cations inside Mg(II) polyporphine film, with their subsequent electrochemical transformation to condensed-structure materials

    International Nuclear Information System (INIS)

    Konev, Dmitry V.; Devillers, Charles H.; Lizgina, Ksenia V.; Zyubina, Tatiana S.; Zyubin, Alexander S.; Maiorova- Valkova, Larisa A.; Vorotyntsev, Mikhail A.

    2014-01-01

    It has been demonstrated that the treatment of the magnesium polyporphine of type I, pMgP-I, by trifluoroacetic acid in acetonitrile may be used to replace initial central Mg(II) cations inside the monomeric macrocycle units by protons, to get a new electroactive polymer, “free-base polyporphine of type I”, pH 2 P-I. In its turn, these inserted protons may be replaced by Zn(II) cations via the film treatment with zinc acetate in organic solvent, to get another new electroactive polymer, “zinc polyporphine of type I”, pZnP-I. These changes of central ions inside monomer units manifest themselves by characteristic modifications of their electroactive properties as well as of UV–visible and IR spectra. Similar to the magnesium polyporphine of type I, pMgP-I, studied in our previous paper (Electrochim. Acta, 2010, 55, 6703) both new polymers are subject to an irreversible electrooxidative transformation into the corresponding polyporphines of type II, pH 2 P-II and pZnP-II. All these polyporphines of type II demonstrate a very broad range of their redox activity, without any potential interval of non-electroactivity. It means that they represent electroactive polymers with a zero-width band gap in the neutral state of the polymer and the Fermi level is located into a broad electronic band for a wide range of the positive and negative oxidation states. Expected molecular structures of all these polymers are discussed

  17. Investigating the in vitro drug release kinetics from controlled release diclofenac potassium-ethocel matrix tablets and the influence of co-excipients on drug release patterns.

    Science.gov (United States)

    Shah, Shefaat Ullah; Shah, Kifayat Ullah; Rehman, Asimur; Khan, Gul Majid

    2011-04-01

    The objective of the study was to formulate and evaluate controlled release polymeric tablets of Diclofenac Potassium for the release rate, release patterns and the mechanism involved in the release process of the drug. Formulations with different types and grades of Ethyl Cellulose Ether derivatives in several drug-to-polymer ratios (D:P) were compressed into tablets using the direct compression method. In vitro drug release studies were performed in phosphate buffer (pH 7.4) as dissolution medium by using USP Method-1 (Rotating Basket Method). Similarity factor f2 and dissimilarity factor f1 were applied for checking the similarities and dissimilarities of the release profiles of different formulations. For the determination of the release mechanism and drug release kinetics various mathematical/kinetic models were employed. It was found that all of the Ethocel polymers could significantly slow down the drug release rate with Ethocel FP polymers being the most efficient, especially at D:P ratios of 10:03 which lead towards the achievement of zero or near zero order release kinetics.

  18. Multi-unit dosage formulations of theophylline for controlled release applications.

    Science.gov (United States)

    Uhumwangho, Michael U; Okor, Roland S

    2007-01-01

    The study was carried out to investigate the drug release profiles of multi-unit dosage formulations of theophylline consisting of both the fast and slow release components in a unit dose. The fast release component consisted of conventional granules of theophylline formed by mixing the drug powder with starch mucilage (20% w/v) while the slow release component consisted of wax granulations of theophylline formed by triturating the drug powder with a melted Carnauba wax (drug:wax ratio, 4:1). The granules were either filled into capsules or tabletted. In the study design, the drug release characteristics of the individual fast or slow release particles were first determined separately and then mixed in various proportions for the purpose of optimizing the drug release profiles. The evaluating parameters were the prompt release in the first 1 h (mp), the maximum release (m infinity) and the time to attain it (t infinity). Total drug content in each capsule or tablet was 300 mg and two of such were used in dissolution studies. The release kinetics and hence the release mechanism was confirmed by measuring the linear regression coefficient (R2 values) of the release data. The release kinetics was generally most consistent with the Higuchi square root of time relationship (R2 = 0.95). indicating a diffusion-controlled mechanism. The mp (mg) and t infinity (h) values for capsules and tablets of the conventional granules were (420 mg, 3 h) and (348 mg, 5 h), respectively, while for the capsules and tablets of the wax granulations mp and t infinity values were (228 mg, 9 h) and (156 mg, 12 h), respectively, indicating that a combination of wax granulation and tableting markedly retarded drug release. In the multi-unit dose formulations where the conventional and wax granulations were mixed in the ratios 2:1, 1:1 and 1:2 (conventional: matrix), the m infinity and t infinity values for the capsules were (378 mg, 6 h), (326 mg, 6 h) and (272 mg, 7 h), reSpectively. The

  19. Meticulous Overview on the Controlled Release Fertilizers

    Directory of Open Access Journals (Sweden)

    Siafu Ibahati Sempeho

    2014-01-01

    Full Text Available Owing to the high demand for fertilizer formulations that will exhaust the possibilities of nutrient use efficiency (NUE, regulate fertilizer consumption, and lessen agrophysicochemical properties and environmental adverse effects instigated by conventional nutrient supply to crops, this review recapitulates controlled release fertilizers (CRFs as a cutting-edge and safe way to supply crops’ nutrients over the conventional ways. Essentially, CRFs entail fertilizer particles intercalated within excipients aiming at reducing the frequency of fertilizer application thereby abating potential adverse effects linked with conventional fertilizer use. Application of nanotechnology and materials engineering in agriculture particularly in the design of CRFs, the distinctions and classification of CRFs, and the economical, agronomical, and environmental aspects of CRFs has been revised putting into account the development and synthesis of CRFs, laboratory CRFs syntheses and testing, and both linear and sigmoid release features of CRF formulations. Methodical account on the mechanism of nutrient release centring on the empirical and mechanistic approaches of predicting nutrient release is given in view of selected mathematical models. Compositions and laboratory preparations of CRFs basing on in situ and graft polymerization are provided alongside the physical methods used in CRFs encapsulation, with an emphasis on the natural polymers, modified clays, and superabsorbent nanocomposite excipients.

  20. NICKEL HYDROXIDE FILMS IN CONTACT WITH AN ELECTROACTIVE SOLUTION. A STUDY EMPLOYING ELECTROCHEMICAL IMPEDANCE MEASUREMENTS

    OpenAIRE

    RICARDO TUCCERI

    2018-01-01

    The deactivation of nickel hydroxide films after prolonged storage times without use was studied. This study was carried out in the context of the Rotating Disc Electrode Voltammetry (RDEV) and Electrochemical Impedance Spectroscopy (EIS) when the nickel hydroxide film contacts an electroactive solution and a redox reaction occurs at the Au-Ni(OH)2|electrolyte interface. Deferasirox (4-(3,5-bis(2- hydroxyphenyl)-1,2,4-triazol-1-yl) benzoic acid) was employed as redox species in solution. Limi...

  1. Electro-active paper for a durable biomimetic actuator

    International Nuclear Information System (INIS)

    Yun, Sung-Ryul; Yun, Gyu Young; Kim, Jung Hwan; Chen, Yi; Kim, Jaehwan

    2009-01-01

    Cellulose electro-active paper (EAPap), known as a smart material, has merits in terms of low voltage operation, light weight, dryness, low power consumption, biodegradability, abundance and low price. Since EAPap requires low power consumption, a remotely driven actuator has been proposed using microwave power transmission. This concept is attractive for many biomimetic systems such as crawling micro-insect robots, flying objects like dragon flies and smart wallpapers. However, the actuation performance of EAPap is sensitive to humidity and degrades with time. Thus, in this paper, a durable EAPap is studied. The fabrication of EAPap is explained and the actuation performance is shown with applied electric field, frequency, humidity level and time. The fabrication process includes dissolving cellulose fibers, eliminating solvent and Li ions with a mixture of deionized water and isopropyl alcohol, washing with water, drying and coating with gold. The morphology of the fabricated EAPap is analyzed by taking scanning electron microscope images and x-ray diffractograms. The actuation performance is tested in terms of bending displacement with frequency, time and humidity level

  2. Controlled release systems containing solid dispersions: strategies and mechanisms.

    Science.gov (United States)

    Tran, Phuong Ha-Lien; Tran, Thao Truong-Dinh; Park, Jun Bom; Lee, Beom-Jin

    2011-10-01

    In addition to a number of highly soluble drugs, most new chemical entities under development are poorly water-soluble drugs generally characterized by an insufficient dissolution rate and a small absorption window, leading to the low bioavailability. Controlled-release (CR) formulations have several potential advantages over conventional dosage forms, such as providing a uniform and prolonged therapeutic effect to improve patient compliance, reducing the frequency of dosing, minimizing the number of side effects, and reducing the strength of the required dose while increasing the effectiveness of the drug. Solid dispersions (SD) can be used to enhance the dissolution rate of poorly water-soluble drugs and to sustain the drug release by choosing an appropriate carrier. Thus, a CR-SD comprises both functions of SD and CR for poorly water-soluble drugs. Such CR dosage forms containing SD provide an immediately available dose for an immediate action followed by a gradual and continuous release of subsequent doses to maintain the plasma concentration of poorly water-soluble drugs over an extended period of time. This review aims to summarize all currently known aspects of controlled release systems containing solid dispersions, focusing on the preparation methods, mechanisms of action and characterization of physicochemical properties of the system.

  3. Fabrication of ketoprofen controlled-release tablets using biopolymeric hydrophilic matrices: in-vitro studies

    International Nuclear Information System (INIS)

    Rashid, S.; Khan, B.A.; Khan, G.M.

    2017-01-01

    Ketoprofen is propionic acid derivative and belongs to the Non-Steroidal anti-inflammatory group of drugs. Due to the short half-life, dosage frequency, patient non-compliance and side effects such as gastrointestinal disturbance, peptic ulceration and gastro intest inal bleeding, it is considered to be good candidate for formulation into controlled release dosage forms. Directly compressed controlled released ( CR) tablets using Acrylic acid derivatives were prepared and evaluated. In-Vitro Physicochemical assessment of the formulated tablets were performed using different physicochemical, dimensional and quality control tests such as weight variation, thickness and diameter, hardness test, friability test, content uniformity, disintegration and dissolution testing. Results of all these tests were formed within acceptable range. The effect of carbomer polymers on the tablet characteristics, drug release rates, release patterns and release kinetics were investigated. The F2-metric technique was applied to compare dissolution profiles of ketoprofen and carbopol tablets with ketoprofen SR - tablets taken as standard preparation. Acrylic acid derivatives when used as polymers resulted in an extended release profile of about 12 h. Using Higuchi's model and the Korsmeyer equation, the drug release mechanism from the tablets was found to be an anomalous type involving diffusion and erosion. Controlled- release Ketoprofen tablets appear to be a good choice for the symptomatic treatment of rheumatoid arthritis and osteoarthritis. Convenient once-daily administration may help improve patient's compliance. (author)

  4. Ibuprofen-loaded poly(lactic-co-glycolic acid films for controlled drug release

    Directory of Open Access Journals (Sweden)

    Pang JM

    2011-04-01

    Full Text Available Jianmei Pang1, Yuxia Luan1, Feifei Li1, Xiaoqing Cai1, Jimin Du2, Zhonghao Li31School of Pharmaceutical Science, Shandong University, Jinan, Shandong Province, PR China; 2School of Chemistry and Chemical Engineering, Anyang Normal University, Henan Province, PR China; 3School of Materials Science and Engineering, Shandong University, Jinan, Shandong Province, PR ChinaAbstract: Ibuprofen- (IBU loaded biocompatible poly(lactic-co-glycolic acid (PLGA films were prepared by spreading polymer/ibuprofen solution on the nonsolvent surface. By controlling the weight ratio of drug and polymer, different drug loading polymer films can be obtained. The synthesized ibuprofen-loaded PLGA films were characterized with scanning electron microscopy, powder X-ray diffraction, and differential scanning calorimetry. The drug release behavior of the as-prepared IBU-loaded PLGA films was studied to reveal their potential application in drug delivery systems. The results show the feasibility of the as-obtained films for controlling drug release. Furthermore, the drug release rate of the film could be controlled by the drug loading content and the release medium. The development of a biodegradable ibuprofen system, based on films, should be of great interest in drug delivery systems.Keywords: ibuprofen, controlled release, poly(lactic-co-glycolic acid, films

  5. Advances in Targeted Pesticides with Environmentally Responsive Controlled Release by Nanotechnology

    Directory of Open Access Journals (Sweden)

    Bingna Huang

    2018-02-01

    Full Text Available Pesticides are the basis for defending against major biological disasters and important for ensuring national food security. Biocompatible, biodegradable, intelligent, and responsive materials are currently an emerging area of interest in the field of efficient, safe, and green pesticide formulation. Using nanotechnology to design and prepare targeted pesticides with environmentally responsive controlled release via compound and chemical modifications has also shown great potential in creating novel formulations. In this review, special attention has been paid to intelligent pesticides with precise controlled release modes that can respond to micro-ecological environment changes such as light-sensitivity, thermo-sensitivity, humidity sensitivity, soil pH, and enzyme activity. Moreover, establishing intelligent and controlled pesticide release technologies using nanomaterials are reported. These technologies could increase pesticide-loading, improve the dispersibility and stability of active ingredients, and promote target ability.

  6. Highly Efficient Thermoresponsive Nanocomposite for Controlled Release Applications

    KAUST Repository

    Yassine, Omar; Zaher, Amir; Li, Erqiang; Alfadhel, Ahmed; Perez, Jose E.; Kavaldzhiev, Mincho; Contreras, Maria F.; Thoroddsen, Sigurdur T; Khashab, Niveen M.; Kosel, Jü rgen

    2016-01-01

    Highly efficient magnetic release from nanocomposite microparticles is shown, which are made of Poly (N-isopropylacrylamide) hydrogel with embedded iron nanowires. A simple microfluidic technique was adopted to fabricate the microparticles with a high control of the nanowire concentration and in a relatively short time compared to chemical synthesis methods. The thermoresponsive microparticles were used for the remotely triggered release of Rhodamine (B). With a magnetic field of only 1 mT and 20 kHz a drug release of 6.5% and 70% was achieved in the continuous and pulsatile modes, respectively. Those release values are similar to the ones commonly obtained using superparamagnetic beads but accomplished with a magnetic field of five orders of magnitude lower power. The high efficiency is a result of the high remanent magnetization of the nanowires, which produce a large torque when exposed to a magnetic field. This causes the nanowires to vibrate, resulting in friction losses and heating. For comparison, microparticles with superparamagnetic beads were also fabricated and tested; while those worked at 73 mT and 600 kHz, no release was observed at the low field conditions. Cytotoxicity assays showed similar and high cell viability for microparticles with nanowires and beads.

  7. Highly Efficient Thermoresponsive Nanocomposite for Controlled Release Applications

    KAUST Repository

    Yassine, Omar

    2016-06-23

    Highly efficient magnetic release from nanocomposite microparticles is shown, which are made of Poly (N-isopropylacrylamide) hydrogel with embedded iron nanowires. A simple microfluidic technique was adopted to fabricate the microparticles with a high control of the nanowire concentration and in a relatively short time compared to chemical synthesis methods. The thermoresponsive microparticles were used for the remotely triggered release of Rhodamine (B). With a magnetic field of only 1 mT and 20 kHz a drug release of 6.5% and 70% was achieved in the continuous and pulsatile modes, respectively. Those release values are similar to the ones commonly obtained using superparamagnetic beads but accomplished with a magnetic field of five orders of magnitude lower power. The high efficiency is a result of the high remanent magnetization of the nanowires, which produce a large torque when exposed to a magnetic field. This causes the nanowires to vibrate, resulting in friction losses and heating. For comparison, microparticles with superparamagnetic beads were also fabricated and tested; while those worked at 73 mT and 600 kHz, no release was observed at the low field conditions. Cytotoxicity assays showed similar and high cell viability for microparticles with nanowires and beads.

  8. Rectal absorption of morphine from controlled release suppositories

    NARCIS (Netherlands)

    Moolenaar, Frits; Meyler, Pim; Frijlink, Erik; Jauw, Tjoe Hang; Visser, Jan; Proost, Johannes

    1995-01-01

    The absorption profiles and bioavailability of morphine in human volunteers (n = 13) were described after oral administration of MS Contin tablets and rectal administration of a newly developed controlled release suppository. By manipulating the viscosity of fatty suppository base an entirely

  9. Human-like robots as platforms for electroactive polymers (EAP)

    Science.gov (United States)

    Bar-Cohen, Yoseph

    2008-03-01

    Human-like robots, which have been a science fiction for many years, are increasingly becoming an engineering reality thanks to many technology advances in recent years. Humans have always sought to imitate the human appearance, functions and intelligence and as the capability progresses they may become our household appliance or even companion. Biomimetic technologies are increasingly becoming common tools to support the development of such robots. As artificial muscles, electroactive polymers (EAP) are offering important actuation capability for making such machines lifelike. The current limitations of EAP are hampering the possibilities that can be adapted in such robots but progress is continually being made. As opposed to other human made machines and devices, this technology raises various questions and concerns that need to be addressed. These include the need to prevent accidents, deliberate harm, or their use in crimes. In this paper the state-of-the-art and the challenges will be reviewed.

  10. Metabolic control of vesicular glutamate transport and release.

    Science.gov (United States)

    Juge, Narinobu; Gray, John A; Omote, Hiroshi; Miyaji, Takaaki; Inoue, Tsuyoshi; Hara, Chiaki; Uneyama, Hisayuki; Edwards, Robert H; Nicoll, Roger A; Moriyama, Yoshinori

    2010-10-06

    Fasting has been used to control epilepsy since antiquity, but the mechanism of coupling between metabolic state and excitatory neurotransmission remains unknown. Previous work has shown that the vesicular glutamate transporters (VGLUTs) required for exocytotic release of glutamate undergo an unusual form of regulation by Cl(-). Using functional reconstitution of the purified VGLUTs into proteoliposomes, we now show that Cl(-) acts as an allosteric activator, and the ketone bodies that increase with fasting inhibit glutamate release by competing with Cl(-) at the site of allosteric regulation. Consistent with these observations, acetoacetate reduced quantal size at hippocampal synapses and suppresses glutamate release and seizures evoked with 4-aminopyridine in the brain. The results indicate an unsuspected link between metabolic state and excitatory neurotransmission through anion-dependent regulation of VGLUT activity. Copyright © 2010 Elsevier Inc. All rights reserved.

  11. Releasable Kinetic Energy-Based Inertial Control of a DFIG Wind Power Plant

    DEFF Research Database (Denmark)

    Lee, Jinsik; Muljadi, Eduard; Sørensen, Poul Ejnar

    2016-01-01

    Wind turbine generators (WTGs) in a wind power plant (WPP) contain different levels of releasable kinetic energy (KE) because of the wake effects. This paper proposes a releasable KE-based inertial control scheme for a doubly fed induction generator (DFIG) WPP that differentiates the contributions....... The proposed scheme adjusts the two loop gains in a DFIG controller depending on its rotor speed so that a DFIG operating at a higher rotor speed releases more KE. The performance of the proposed scheme was investigated under various wind conditions. The results clearly indicate that the proposed scheme...

  12. Ionic interactions in electroactive self-assembled monolayers of ferrocene species

    Science.gov (United States)

    Delong, Hugh C.; Donohue, John J.; Buttry, Daniel A.

    1991-04-01

    The electrochemical and interfacial behavior of two types of electroactive self-assembled monolayer systems is investigated at gold electrodes. The first type is a ferrocene-based surfactant (a redox surfactant) derived from (dimethylamino)methylferrocene via quaternization of the amino group with various n-alkylbromides. These have a long alkyl chain with 16 or 18 carbons in the chain pendent from the cationic ammonium group. These are referred to as C16 and C18. The second type is a ferrocene-based dimeric species with a disulfide functional group capable of providing a permanent anchor to the Au electrode, thus endowing monolayers of this species with exceptional stability towards desorption. The electrochemical quartz crystal microbalance (EQM) is used to monitor the mass changes which occur at the electrode surface during the redox processes of these two species.

  13. Controlled release of cytokines using silk-biomaterials for macrophage polarization.

    Science.gov (United States)

    Reeves, Andrew R D; Spiller, Kara L; Freytes, Donald O; Vunjak-Novakovic, Gordana; Kaplan, David L

    2015-12-01

    Polarization of macrophages into an inflammatory (M1) or anti-inflammatory (M2) phenotype is important for clearing pathogens and wound repair, however chronic activation of either type of macrophage has been implicated in several diseases. Methods to locally control the polarization of macrophages is of great interest for biomedical implants and tissue engineering. To that end, silk protein was used to form biopolymer films that release either IFN-γ or IL-4 to control the polarization of macrophages. Modulation of the solubility of the silk films through regulation of β-sheet (crystalline) content enabled a short-term release (4-8 h) of either cytokine, with smaller amounts released out to 24 h. Altering the solubility of the films was accomplished by varying the time that the films were exposed to water vapor. The released IFN-γ or IL-4 induced polarization of THP-1 derived macrophages into the M1 or M2 phenotypes, respectively. The silk biomaterials were able to release enough IFN-γ or IL-4 to repolarize the macrophage from M1 to M2 and vice versa, demonstrating the well-established plasticity of macrophages. High β-sheet content films that are not soluble and do not release the trapped cytokines were also able to polarize macrophages that adhered to the surface through degradation of the silk protein. Chemically conjugating IFN-γ to silk films through disulfide bonds allowed for longer-term release to 10 days. The release of covalently attached IFN-γ from the films was also able to polarize M1 macrophages in vitro. Thus, the strategy described here offers new approaches to utilizing biomaterials for directing the polarization of macrophages. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Sol-gel Derived Warfarin - Silica Composites for Controlled Drug Release.

    Science.gov (United States)

    Dolinina, Ekaterina S; Parfenyuk, Elena V

    2017-01-01

    Warfarin, commonly used anticoagulant in clinic, has serious shortcomings due to its unsatisfactory pharmacodynamics. One of the efficient ways for the improvement of pharmacological and consumer properties of drugs is the development of optimal drug delivery systems. The aim of this work is to synthesize novel warfarin - silica composites and to study in vitro the drug release kinetics to obtain the composites with controlled release. The composites of warfarin with unmodified (UMS) and mercaptopropyl modified silica (MPMS) were synthesized by sol-gel method. The composite formation was confirmed by FTIR spectra. The concentrations of warfarin released to media with pH 1.6, 6.8 and 7.4 were measured using UV spectroscopy. The drug release profiles from the solid composites were described by a series of kinetic models which includes zero order kinetics, first order kinetics, the modified Korsmeyer-Peppas model and Hixson-Crowell model. The synthesized sol-gel composites have different kinetic behavior in the studied media. In contrast to the warfarin composite with unmodified silica, the drug release from the composite with mercaptopropyl modified silica follows zero order kinetics for 24 h irrespective to the release medium pH due to mixed mechanism (duffusion + degradation and/or disintegration of silica matrix). The obtained results showed that warfarin - silica sol-gel composites have a potential application for the development of novel oral formulation of the drug with controlled delivery. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  15. Mechanical properties of cellulose electro-active paper under different environmental conditions

    International Nuclear Information System (INIS)

    Kim, Heung Soo; Kim, Jaehwan; Jung, Woochul; Ampofo, Joshua; Craft, William; Sankar, Jagannathan

    2008-01-01

    The mechanical properties of cellulose-based electro-active paper (EAPap) are investigated under various environmental conditions. Cellulose EAPap has been discovered as a smart material that can be used as both sensor and actuator. Its advantages include low voltage operation, light weight, low power consumption, biodegradability and low cost. EAPap is made with cellulose paper coated with thin electrodes. EAPap shows a reversible and reproducible bending movement as well as longitudinal displacement under an electric field. However, EAPap is a complex anisotropic material which has not been fully characterized. This study investigates the mechanical properties of cellulose-based EAPap, including Young's modulus, yield strength, ultimate strength and creep, along with orientation directions, humidity and temperature levels. To test the materials in different humidity and temperature levels, a special material testing system was made that can control the testing environmental conditions. The initial Young's modulus of EAPap is in the range of 4–9 GPa, which was higher than that of other polymer materials. Also, the Young's modulus is orientation dependent, which may be associated with the piezoelectricity of EAPap materials. The elastic strength and stiffness gradually decreased when the humidity and temperature were increased. Creep and relaxation were observed under constant stress and strain, respectively. Through scanning electron microscopy, EAPap is shown to exhibit both layered and oriented cellulose macromolecular structures that impact both the elastic and plastic behavior

  16. Predictive property models for use in design of controlled release of pesticides

    DEFF Research Database (Denmark)

    Suné, Nuria Muro; Gani, Rafiqul; Bell, G.

    2005-01-01

    A model capable of predicting the release of an Active Ingredient (AI) from a specific device would be very useful in the field of pesticide controlled release technology for design purposes. For the release of an AI from a microcapsule a mathematical model is briefly presented here, as an introd...

  17. The present status of rare gas release control

    International Nuclear Information System (INIS)

    Yamamoto, Hiroshi

    1974-01-01

    Of the rare gases Ar, Kr and Xe released from nuclear facilities, the problem of release control can be confined to 41 Ar, 85 Kr and 133 Xe. The cases of the latter two are described, as 41 Ar is not much significant. 133 Xe, having relatively short half-life, can be dealt sufficiently by holding-up in case of light water reactors. 85 Kr of long half-life must be removed : the methods are low temperature adsorption, liquefaction distillation, absorption and diaphragm method. As for future problem, there is disposal of concentrated rare gas. (Mori, K.)

  18. Nanoreinforced Hydrogels for Tissue Engineering: Biomaterials that are Compatible with Load-Bearing and Electroactive Tissues

    DEFF Research Database (Denmark)

    Mehrali, Mehdi; Thakur, Ashish; Pennisi, Christian Pablo

    2017-01-01

    , mechanical, and electrical properties. Here, recent advances in the fabrication and application of nanocomposite hydrogels in tissue engineering applications are described, with specific attention toward skeletal and electroactive tissues, such as cardiac, nerve, bone, cartilage, and skeletal muscle......Given their highly porous nature and excellent water retention, hydrogel-based biomaterials can mimic critical properties of the native cellular environment. However, their potential to emulate the electromechanical milieu of native tissues or conform well with the curved topology of human organs...

  19. Controlled release of tetracycline-HCl from halloysite-polymer composite films.

    Science.gov (United States)

    Ward, Christopher J; Song, Shang; Davis, Edward W

    2010-10-01

    The first direct comparison between two common methods for loading halloysite with a small molecule for controlled release is presented. While the methods differ in the degree of simplicity, they provide essentially the same level of loading and release kinetics. A tentative explanation of the "burst" effect often seen in the release of low molecular weight molecules from halloysite is provided. The ability of halloysite to mediate the release rate of a water soluble drug, tetracycline, from solution cast polyvinyl alcohol and polymethyl methacrylate films was evaluated. In some films, montmorillonite was also incorporated. The addition of montmorillonite to solutions used to cast tetracycline containing films significantly reduced the release rate from the dried films. The same overall effect was seen when the drug was loaded into halloysite prior to preparation of the films. In both cases, the release was best fit with the simple Higuchi model. However, when montmorillonite was added to solutions of polyvinyl alcohol and drug loaded halloysite the release profiles were better fit by the Ritgar-Peppas model for anomalous transport. Release from polymethyl methacrylate was reduced by a factor of three by incorporating the drug in halloysite prior to producing the films.

  20. Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Xiaorui, E-mail: gxr_1320@sina.com [College of Science, Hebei University of Engineering, Handan 056038 (China); School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA (United Kingdom); Lei, Lixu [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); O' Hare, Dermot [Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA (United Kingdom); Xie, Juan [College of Science, Hebei University of Engineering, Handan 056038 (China); Gao, Pengran [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); Chang, Tao [College of Science, Hebei University of Engineering, Handan 056038 (China)

    2013-07-15

    Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg–Al and Mg–Fe layered double hydroxides (LDHs) have been synthesized by the calcination–rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV–vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO{sub 3}{sup 2−} solutions imply that Mg{sub 3}Al–VC LDH is a better controlled release system than Mg{sub 3}Fe–VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO{sub 3}{sup 2−} solution. - Graphical abstract: Vitamin C anions have been intercalated in the interlayer space of layered double hydroxide and released in CO{sub 3}{sup 2−} solution and deionised water. - Highlights: • Vitamin C intercalated Mg–Al and Mg–Fe layered double hydroxides were prepared. • Release property of vitamin C in aqueous CO{sub 3}{sup 2−} solution is better. • Avrami-Erofe’ev and first-order models provide better fit for release results. • Diffusion-controlled and ion exchange processes occur in deionised water. • An ion exchange process occurs in CO{sub 3}{sup 2−} solution.

  1. pH-controlled drug loading and release from biodegradable microcapsules.

    Science.gov (United States)

    Zhao, Qinghe; Li, Bingyun

    2008-12-01

    Microcapsules made of biopolymers are of both scientific and technological interest and have many potential applications in medicine, including their use as controlled drug delivery devices. The present study makes use of the electrostatic interaction between polycations and polyanions to form a multilayered microcapsule shell and also to control the loading and release of charged drug molecules inside the microcapsule. Micron-sized calcium carbonate (CaCO3) particles were synthesized and integrated with chondroitin sulfate (CS) through a reaction between sodium carbonate and calcium nitrate tetrahydrate solutions suspended with CS macromolecules. Oppositely charged biopolymers were alternately deposited onto the synthesized particles using electrostatic layer-by-layer self-assembly, and glutaraldehyde was introduced to cross-link the multilayered shell structure. Microcapsules integrated with CS inside the multilayered shells were obtained after decomposition of the CaCO3 templates. The integration of a matrix (i.e., CS) permitted the subsequent selective control of drug loading and release. The CS-integrated microcapsules were loaded with a model drug, bovine serum albumin labeled with fluorescein isothiocyanate (FITC-BSA), and it was shown that pH was an effective means of controlling the loading and release of FITC-BSA. Such CS-integrated microcapsules may be used for controlled localized drug delivery as biodegradable devices, which have advantages in reducing systemic side effects and increasing drug efficacy.

  2. Considerations for Contractile Electroactive Materials and Actuators

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, Lenore; Erickson, Carl J.; Meixler, Lewis D.; Ascione, George; Gentile, Charles A.; Tilson, Carl; Bernasek, Stephen L.; Abelev, Esta

    2010-02-19

    Ras Labs produces electroactive polymer (EAP) based materials and actuators that bend, swell, ripple and now contract (new development) with low electric input. This is an important attribute because of the ability of contraction to produce life-like motion. The mechanism of contraction is not well understood. Radionuclide-labeled experiments were conducted to follow the movement of electrolytes and water in these EAPs when activated. Extreme temperature experiments were performed on the contractile EAPs with very favorable results. One of the biggest challenges in developing these actuators, however, is the electrode-EAP interface because of the pronounced movement of the EAP. Plasma treatments of metallic electrodes were investigated in order to improve the attachment of the embedded electrodes to the EAP material. Surface analysis, adhesive testing, and mechanical testing were conducted to test metal surfaces and metal-polymer interfaces. The nitrogen plasma treatment of titanium produced a strong metal-polymer interface; however, oxygen plasma treatment of both stainless steel and titanium produced even stronger metal-polymer interfaces. Plasma treatment of the electrodes allows for the embedded electrodes and the EAP material of the actuator to work and move as a unit, with no detachment, by significantly improving the metal-polymer interface.

  3. Considerations for Electroactive Polymeric Materials and Actuators

    International Nuclear Information System (INIS)

    Rasmussen, Lenore; Erickson, Carl J.; Meixler, Lewis D.; Ascione, George; Gentile, Charles A.; Tilson, Carl; Bernasek, Stephen L.; Abelev, Esta

    2010-01-01

    Ras Labs produces electroactive polymer (EAP) based materials and actuators that bend, swell, ripple and now contract (new development) with low electric input. This is an important attribute because of the ability of contraction to produce life-like motion. The mechanism of contraction is not well understood. Radionuclide-labeled experiments were conducted to follow the movement of electrolytes and water in these EAPs when activated. Extreme temperature experiments were performed on the contractile EAPs with very favorable results. One of the biggest challenges in developing these actuators, however, is the electrode-EAP interface because of the pronounced movement of the EAP. Plasma treatments of metallic electrodes were investigated in order to improve the attachment of the embedded electrodes to the EAP material. Surface analysis, adhesive testing, and mechanical testing were conducted to test metal surfaces and metal-polymer interfaces. The nitrogen plasma treatment of titanium produced a strong metal-polymer interface; however, oxygen plasma treatment of both stainless steel and titanium produced even stronger metal-polymer interfaces. Plasma treatment of the electrodes allows for the embedded electrodes and the EAP material of the actuator to work and move as a unit, with no detachment, by significantly improving the metal-polymer interface.

  4. A novel and alternative approach to controlled release drug delivery system based on solid dispersion technique

    Directory of Open Access Journals (Sweden)

    Tapan Kumar Giri

    2012-12-01

    Full Text Available The solid dispersion method was originally used to improve the dissolution properties and the bioavailability of poorly water soluble drugs by dispersing them into water soluble carriers. In addition to the above, dissolution retardation through solid dispersion technique using water insoluble and water swellable polymer for the development of controlled release dosage forms has become a field of interest in recent years. Development of controlled release solid dispersion has a great advantage for bypassing the risk of a burst release of drug; since the structure of the solid dispersion is monolithic where drug molecules homogeneously disperse. Despite the remarkable potential and extensive research being conducted on controlled release solid dispersion system, commercialization and large scale production are limited. The author expects that recent technological advances may overcome the existing limitations and facilitate the commercial utilization of the techniques for manufacture of controlled release solid dispersions. This article begins with an overview of the different carriers being used for the preparation of controlled release solid dispersion and also different techniques being used for the purpose. Kinetics of drug release from these controlled release solid dispersions and the relevant mathematical modeling have also been reviewed in this manuscript.

  5. Controlled release of simvastatin from biomimetic β-TCP drug delivery system.

    Directory of Open Access Journals (Sweden)

    Joshua Chou

    Full Text Available Simvastatin have been shown to induce bone formation and there is currently a urgent need to develop an appropriate delivery system to sustain the release of the drug to increase therapeutic efficacy whilst reducing side effects. In this study, a novel drug delivery system for simvastatin by means of hydrothermally converting marine exoskeletons to biocompatible beta-tricalcium phosphate was investigated. Furthermore, the release of simvastatin was controlled by the addition of an outer apatite coating layer. The samples were characterized by x-ray diffraction analysis, fourier transform infrared spectroscopy, scanning electron microscopy and mass spectroscopy confirming the conversion process. The in-vitro dissolution of key chemical compositional elements and the release of simvastatin were measured in simulated body fluid solution showing controlled release with reduction of approximately 25% compared with un-coated samples. This study shows the potential applications of marine structures as a drug delivery system for simvastatin.

  6. Synthesis and surface characterization of electroactive conducting polymers and polyurethane coatings

    Science.gov (United States)

    Vang, Chur Kalec

    The direct electrodeposition of electroactive conducting polymers (ECPs) on active metals such as iron, steel, and aluminum is complicated by the concomitant metal oxidation that occurs at the positive potentials required for polymer formation. In the case of aluminum and its alloys, the oxide layer that forms is an insulator that blocks electron transfer and impedes polymer formation and deposition. As a result, only patchy, nonuniform polymer films are obtained. Electron transfer mediation is a well-known technique for overcoming kinetic limitations of electron transfer at metal electrodes. In this dissertation, we report the use of electron transfer mediation for the direct electrodeposition of polypyrrole onto aluminum and onto Al 2024-T3 alloy. The first few chapters focus on the electrochemistry and use of Tiron RTM (4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt) as the mediator. Electroactive conductive polymers (ECPs) were also being investigated for corrosion protection of Al alloys, with a view toward replacement of chromate-based coating systems. The use of electrochemical methods clearly indicated that the electrodeposited Ppy coatings had altered the corrosion behavior of the Al alloy. Degradation mechanisms for self-priming (unicoat), high-gloss, and fluorinated polyurethane aircraft coatings exposed to QUV/H2O radiation were carried out using linear and step-scan photoacoustic (S2-PA) FTIR spectroscopy (Chapters 7--9). FTIR spectroscopic analysis indicated that, as the depth of sampling increased from film-air to film-substrate, an increase of free carbonyl components was observed. These free carbonyl groups are indicative of polyurethane components. Exposure of the polyurethane coating to prolonged periods of extreme weathering conditions indicated a loss of both polyurethane/polyurea components at the air interface, which has lead to an increase of disordered hydrogen-bonding formations. Contact angle measurement further indicated that as

  7. Guest Editorial Introduction to the focused Section on electroactive Polymer Mechatronics

    DEFF Research Database (Denmark)

    Carpi, Federico; Kornbluh, Roy; Sommer-Larsen, Peter

    2011-01-01

    Mechatronic devices and systems based on so-called electroactive polymers (EAPs) represent a fast-growing and promising scientific field of research and development. EAPs consist of materials capable of changing dimensions and/or shape in response to suitable electrical stimuli. These polymers show...... unique properties, such as sizable electrically driven active strains or stresses, high mechanical flexibility, lowdensity, structural simplicity, ease of processing and scalability, no acoustic noise, and, in most cases, low costs. EAPs are today studied for applications that so far have been......, this Focused Section collects together a selection of papers dealing with a number of topics related to science and technology of EAPs. Following a brief introduction to the field, this Editorial provides an overview on papers dealing with EAPs published in previous issues of this journal, introduces...

  8. Limited mobility of target pests crucially lowers controllability when sterile insect releases are spatiotemporally biased.

    Science.gov (United States)

    Ikegawa, Yusuke; Himuro, Chihiro

    2017-05-21

    The sterile insect technique (SIT) is a genetic pest control method wherein mass-reared sterile insects are periodically released into the wild, thereby impeding the successful reproduction of fertile pests. In Okinawa Prefecture, Japan, the SIT has been implemented to eradicate the West Indian sweet potato weevil Euscepes postfasciatus (Fairmaire), which is a flightless agricultural pest of sweet potatoes. It is known that E. postfasciatus is much less mobile than other insects to which the SIT has been applied. However, previous theoretical studies have rarely examined effects of low mobility of target pests and variation in the spatiotemporal evenness of sterile insect releases. To theoretically examine the effects of spatiotemporal evenness on the regional eradication of less mobile pests, we constructed a simple two-patch population model comprised of a pest and sterile insect moving between two habitats, and numerically simulated different release strategies (varying the number of released sterile insects and release intervals). We found that spatially biased releases allowed the pest to spatially escape from the sterile insect, and thus intensively lowered its controllability. However, we showed that the temporally counterbalancing spatially biased releases by swapping the number of released insects in the two habitats at every release (called temporal balancing) could greatly mitigate this negative effect and promote the controllability. We also showed that the negative effect of spatiotemporally biased releases was a result of the limited mobility of the target insect. Although directed dispersal of the insects in response to habitats of differing quality could lower the controllability in the more productive habitat, the temporal balancing could promote and eventually maximize the controllability as released insects increased. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Development and evaluation of controlled-release buccoadhesive verapamil hydrochloride tablets

    Directory of Open Access Journals (Sweden)

    Emami J.

    2008-05-01

    Full Text Available Background and purpose of the study: Verapamil hydrochloride is a calcium channel blocker which is used in the control of supraventricular arrhythmia, hypertension and myocardial infraction. There are considerable inter-individual variations in serum concencentration of verpamil due to variation in the extent of hepatic metabolism. In this study controlled-release buccoadhesive tablets of verapamil hydrochloride (VPH were prepared in order to achieve constant plasma concentrations, to improve the bioavailability by the avoidance of hepatic first-pass metabolism, and to prevent frequent administration. Materials and methods: Tablets containing fixed amount of VPH were prepared by direct compression method using polymers like carbomer (CP, hydroxypropylmethyl cellulose (HPMC and sodium carboxymethyl cellulose (NaCMC in various combination and ratios and evaluated for thickness, weight variation, hardness, drug content uniformity, swelling, mucoadhesive strength, drug release and possible interaction between ingredients. Results: All tablets were acceptable with regard to thickness, weight variation, hardness, and drug content. The maximum bioadhesive strength was observed in tablets formulated with a combination of CP-NaCMC followed by CP-HPMC and NaCMC-HPMC.  Decreasing the content of CP in CP-HPMC tablets or NaCMC in CP-NaCMC or NaCMC-HPMC systems resulted in decrease in detachment forces. Lower release rates were observed by lowering the content of CP in CP-HPMC containing formulations or NaCMC in tablets which contained CP-NaCMC or NaCMC-HPMC. The release behavior was non-Fickian controlled by a combination of diffusion and chain relaxation mechanisms and best fitted zero-order kinetics. Conclusion: The buccoadhesive VPH tablets containing 53% CP and 13.3% HPMC showed suitable release kinetics (n = 0.78, K0 zero order release = 4.11 mg/h, MDT = 5.66 h and adhesive properties and did not show any interaction between polymers and drug based on

  10. Controlled release of bioactive PDGF-AA from a hydrogel/nanoparticle composite.

    Science.gov (United States)

    Elliott Donaghue, Irja; Shoichet, Molly S

    2015-10-01

    Polymer excipients, such as low molar mass poly(ethylene glycol) (PEG), have shown contradictory effects on protein stability when co-encapsulated in polymeric nanoparticles. To gain further insight into these effects, platelet-derived growth factor (PDGF-AA) was encapsulated in polymeric nanoparticles with vs. without PEG. PDGF-AA is a particularly compelling protein, as it has been demonstrated to promote cell survival and induce the oligodendrocyte differentiation of neural stem/progenitor cells (NSPCs) both in vitro and in vivo. Here we show, for the first time, the controlled release of bioactive PDGF-AA from an injectable nanoparticle/hydrogel drug delivery system (DDS). PDGF-AA was encapsulated, with high efficiency, in poly(lactide-co-glycolide) nanoparticles, and its release from the drug delivery system was followed over 21 d. Interestingly, the co-encapsulation of low molecular weight poly(ethylene glycol) increased the PDGF-AA loading but, unexpectedly, accelerated the aggregation of PDGF-AA, resulting in reduced activity and detection by enzyme-linked immunosorbent assay (ELISA). In the absence of PEG, released PDGF-AA remained bioactive as demonstrated with NSPC oligodendrocyte differentiation, similar to positive controls, and significantly different from untreated controls. This work presents a novel delivery method for differentiation factors, such as PDGF-AA, and provides insights into the contradictory effects reported in the literature of excipients, such as PEG, on the loading and release of proteins from polymeric nanoparticles. Previously, the polymer poly(ethylene glycol) (PEG) has been used in many biomaterials applications, from surface coatings to the encapsulation of proteins. In this work, we demonstrate that, unexpectedly, low molecular weight PEG has a deleterious effect on the release of the encapsulated protein platelet-derived growth factor AA (PDGF-AA). We also demonstrate release of bioactive PDGF-AA (in the absence of PEG

  11. Acoustically Triggered Disassembly of Multilayered Polyelectrolyte Thin Films through Gigahertz Resonators for Controlled Drug Release Applications

    Directory of Open Access Journals (Sweden)

    Zhixin Zhang

    2016-11-01

    Full Text Available Controlled drug release has a high priority for the development of modern medicine and biochemistry. To develop a versatile method for controlled release, a miniaturized acoustic gigahertz (GHz resonator is designed and fabricated which can transfer electric supply to mechanical vibrations. By contacting with liquid, the GHz resonator directly excites streaming flows and induces physical shear stress to tear the multilayered polyelectrolyte (PET thin films. Due to the ultra-high working frequency, the shear stress is greatly intensified, which results in a controlled disassembling of the PET thin films. This technique is demonstrated as an effective method to trigger and control the drug release. Both theory analysis and controlled release experiments prove the thin film destruction and the drug release.

  12. Antimicrobial beeswax coated polylactide films with silver control release capacity.

    Science.gov (United States)

    Martínez-Abad, Antonio; Lagarón, Jose Maria; Ocio, María Jose

    2014-03-17

    Although the application of silver based antimicrobial systems is a widespread technology, its implementation in areas such as food packaging is still challenging. The present paper describes the fabrication of poly(lactic acid) (PLA) coated with beeswax with controlled release properties for sustained antimicrobial performance. Release of silver ions from the polymers was monitored voltammetrically under various conditions (surface contact, immersion in various liquid media and at different pH values) throughout at least 7days. A higher release was noted with decreasing pH while surface release was much slower than the release when immersed in liquid medium. While uncoated films demonstrated a high burst release which in some instances implied surpassing some current migration restrictions (food), the addition of a beeswax layer allowed a sustained release of the antimicrobial compound. Increasing the thickness of the beeswax layer resulted in an increase in the water barrier properties of the films while reducing the relatively constant values of sustained release. Antimicrobial performance was correlated with the release of silver ions, indicating threshold concentrations for biocide action of films displayed a strong bactericidal effect against Salmonella enterica. The application of this functional barrier thus offers the possibility of tuning the release profiles of the films to suit a specific application and puts forth the possible suitability of these materials for food packaging or other migration sensitive applications. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Nanoscale architectural tuning of parylene patch devices to control therapeutic release rates

    International Nuclear Information System (INIS)

    Pierstorff, Erik; Lam, Robert; Ho, Dean

    2008-01-01

    The advent of therapeutic functionalized implant coatings has significantly impacted the medical device field by enabling prolonged device functionality for enhanced patient treatment. Incorporation of drug release from a stable, biocompatible surface is instrumental in decreasing systemic application of toxic therapeutics and increasing the lifespan of implants by the incorporation of antibiotics and anti-inflammatories. In this study, we have developed a parylene C-based device for controlled release of Doxorubicin, an anti-cancer chemotherapy and definitive read-out for preserved drug functionality, and further characterized the parylene deposition condition-dependent tunability of drug release. Drug release is controlled by the deposition of a layer of 20-200 nm thick parylene over the drug layer. This places a porous layer above the Doxorubicin, limiting drug elution based on drug accessibility to solvent and the solvent used. An increase in the thickness of the porous top layer prolongs the elution of active drug from the device from, in the conditions tested, the order of 10 min to the order of 2 d in water and from the order of 10 min to no elution in PBS. Thus, the controlled release of an anti-cancer therapeutic has been achieved via scalably fabricated, parylene C-encapsulated drug delivery devices.

  14. Chitosan/alginate based multilayers to control drug release from ophthalmic lens.

    Science.gov (United States)

    Silva, Diana; Pinto, Luís F V; Bozukova, Dimitriya; Santos, Luís F; Serro, Ana Paula; Saramago, Benilde

    2016-11-01

    In this study we investigated the possibility of using layer-by-layer deposition, based in natural polymers (chitosan and alginate), to control the release of different ophthalmic drugs from three types of lens materials: a silicone-based hydrogel recently proposed by our group as drug releasing soft contact lens (SCL) material and two commercially available materials: CI26Y for intraocular lens (IOLs) and Definitive 50 for SCLs. The optimised coating, consisting in one double layer of (alginate - CaCl2)/(chitosan+glyoxal) topped with a final alginate-CaCl2 layer to avoid chitosan degradation by tear fluid proteins, proved to have excellent features to control the release of the anti-inflammatory, diclofenac, while keeping or improving the physical properties of the lenses. The coating leads to a controlled release of diclofenac from SCL and IOL materials for, at least, one week. Due to its high hydrophilicity (water contact angle≈0) and biocompatibility, it should avoid the use of further surface treatments to enhance the useŕs comfort. However, the barrier effect of this coating is specific for diclofenac, giving evidence to the need of optimizing the chemical composition of the layers in view of the desired drug. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Controlled release hydrophilic matrix tablet formulations of isoniazid: design and in vitro studies.

    Science.gov (United States)

    Hiremath, Praveen S; Saha, Ranendra N

    2008-01-01

    The aim of the present investigation was to develop oral controlled release matrix tablet formulations of isoniazid using hydroxypropyl methylcellulose (HPMC) as a hydrophilic release retardant polymer and to study the influence of various formulation factors like proportion of the polymer, polymer viscosity grade, compression force, and release media on the in vitro release characteristics of the drug. The formulations were developed using wet granulation technology. The in vitro release studies were performed using US Pharmacopoeia type 1 apparatus (basket method) in 900 ml of pH 7.4 phosphate buffer at 100 rpm. The release kinetics was analyzed using Korsmeyer-Peppas model. The release profiles were also analyzed using statistical method (one-way analysis of variance) and f (2) metric values. The release profiles found to follow Higuchi's square root kinetics model irrespective of the polymer ratio and the viscosity grade used. The results in the present investigation confirm that the release rate of the drug from the HPMC matrices is highly influenced by the drug/HPMC ratio and viscosity grade of the HPMC. Also, the effect of compression force and release media was found to be significant on the release profiles of isoniazid from HPMC matrix tablets. The release mechanism was found to be anomalous non-Fickian diffusion in all the cases. In the present investigation, a series of controlled release formulations of isoniazid were developed with different release rates and duration so that these formulations could further be assessed from the in vivo bioavailability studies. The formulations were found to be stable and reproducible.

  16. Metal-organic framework tethering PNIPAM for ON-OFF controlled release in solution.

    Science.gov (United States)

    Nagata, Shunjiro; Kokado, Kenta; Sada, Kazuki

    2015-05-21

    A smart metal-organic framework (MOF) exhibiting controlled release was achieved by modification with a thermoresponsive polymer (PNIPAM) via a surface-selective post-synthetic modification technique. Simple temperature variation readily switches "open" (lower temperature) and "closed" (higher temperature) states of the polymer-modified MOF through conformational change of PNIPAM grafted onto the MOF, resulting in controlled release of the included guest molecules such as resorufin, caffeine, and procainamide.

  17. CONTROLLED-RELEASE OF PARACETAMOL FROM AMYLODEXTRIN TABLETS - IN-VITRO AND IN-VIVO RESULTS

    NARCIS (Netherlands)

    VANDERVEEN, J; EISSENS, AC; LERK, CF

    Amylodextrin is a suitable excipient for the design of solid controlled-release systems. The release of paracetamol from tablets containing 30% drug and 70% amylodextrin was studied in vitro and in vivo. In vitro dissolution profiles showed almost-constant drug release rates during 8 hr, when

  18. Core/shell PLGA microspheres with controllable in vivo release profile via rational core phase design.

    Science.gov (United States)

    Yu, Meiling; Yao, Qing; Zhang, Yan; Chen, Huilin; He, Haibing; Zhang, Yu; Yin, Tian; Tang, Xing; Xu, Hui

    2018-02-27

    Highly soluble drugs tend to release from preparations at high speeds, which make them need to be taken at frequent intervals. Additionally, some drugs need to be controlled to release in vivo at certain periods, so as to achieve therapeutic effects. Thus, the objective of this study is to design injectable microparticulate systems with controllable in vivo release profile. Biodegradable PLGA was used as the matrix material to fabricate microspheres using the traditional double emulsification-solvent evaporation method as well as improved techniques, with gel (5% gelatine or 25% F127) or LP powders as the inner phases. Their physicochemical properties were systemically investigated. Microspheres prepared by modified methods had an increase in drug loading (15.50, 16.72, 15.66%, respectively) and encapsulation efficiencies (73.46, 79.42, 74.40%, respectively) when compared with traditional methods (12.01 and 57.06%). The morphology of the particles was characterized by optical microscope (OM) and scanning electron microscopy (SEM), and the amorphous nature of the encapsulated drug was confirmed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. To evaluate their release behaviour, the in vitro degradation, in vitro release and in vivo pharmacodynamics were subsequently studied. Traditional microspheres prepared in this study with water as the inner phase had a relatively short release period within 16 d when compared with modified microspheres with 5% gelatine as the inner phase, which resulted in a smooth release profile and appropriate plasma LP concentrations over 21 d. Thus this type of modified microspheres can be better used in drugs requiring sustained release. The other two formulations containing 25% F127 and LP micropowders presented two-stage release profiles, resulting in fluctuant plasma LP concentrations which may be suitable for drugs requiring controlled release. All the results suggested that drug release rates from

  19. Microfluidic Device for Controllable Chemical Release via Field-Actuated Membrane Incorporating Nanoparticles

    Directory of Open Access Journals (Sweden)

    Xiang Wang

    2013-01-01

    Full Text Available We report a robust magnetic-membrane-based microfluidic platform for controllable chemical release. The magnetic membrane was prepared by mixing polydimethylsiloxane (PDMS and carbonyl-iron nanoparticles together to obtain a flexible thin film. With combined, simultaneous regulation of magnetic stimulus and mechanical pumping, the desired chemical release rate can easily be realized. For example, the dose release experimental data was well fitted by a mathematical sigmoidal model, exhibiting a typical dose-response relationship, which shows promise in providing significant guidance for on-demand drug delivery. To test the platform’s feasibility, our microfluidic device was employed in an experiment involving Escherichia coli culture under controlled antibiotic ciprofloxacin exposure, and the expected outcomes were successfully obtained. Our experimental results indicate that such a microfluidic device, with high accuracy and easy manipulation properties, can legitimately be characterized as active chemical release system.

  20. Microfluidic Device for Controllable Chemical Release via Field-Actuated Membrane Incorporating Nanoparticles

    KAUST Repository

    Wang, Xiang; Li, Shunbo; Wang, Limu; Yi, Xin; Hui, Yu Sanna; Qin, Jianhua; Wen, Weijia

    2013-01-01

    We report a robust magnetic-membrane-based microfluidic platform for controllable chemical release. The magnetic membrane was prepared by mixing polydimethylsiloxane (PDMS) and carbonyl-iron nanoparticles together to obtain a flexible thin film. With combined, simultaneous regulation of magnetic stimulus and mechanical pumping, the desired chemical release rate can easily be realized. For example, the dose release experimental data was well fitted by a mathematical sigmoidal model, exhibiting a typical dose-response relationship, which shows promise in providing significant guidance for on-demand drug delivery. To test the platform’s feasibility, our microfluidic device was employed in an experiment involving Escherichia coli culture under controlled antibiotic ciprofloxacin exposure, and the expected outcomes were successfully obtained. Our experimental results indicate that such a microfluidic device, with high accuracy and easy manipulation properties, can legitimately be characterized as active chemical release system.

  1. Microfluidic Device for Controllable Chemical Release via Field-Actuated Membrane Incorporating Nanoparticles

    KAUST Repository

    Wang, Xiang

    2013-01-01

    We report a robust magnetic-membrane-based microfluidic platform for controllable chemical release. The magnetic membrane was prepared by mixing polydimethylsiloxane (PDMS) and carbonyl-iron nanoparticles together to obtain a flexible thin film. With combined, simultaneous regulation of magnetic stimulus and mechanical pumping, the desired chemical release rate can easily be realized. For example, the dose release experimental data was well fitted by a mathematical sigmoidal model, exhibiting a typical dose-response relationship, which shows promise in providing significant guidance for on-demand drug delivery. To test the platform’s feasibility, our microfluidic device was employed in an experiment involving Escherichia coli culture under controlled antibiotic ciprofloxacin exposure, and the expected outcomes were successfully obtained. Our experimental results indicate that such a microfluidic device, with high accuracy and easy manipulation properties, can legitimately be characterized as active chemical release system.

  2. Controlled release of glaucocalyxin - a self-nanoemulsifying system from osmotic pump tablets with enhanced bioavailability.

    Science.gov (United States)

    Yanfei, Miao; Guoguang, Chen; Lili, Ren; Pingkai, Ouyang

    2017-03-01

    The purpose of this study was to develop a new formulation to enhance the bioavailability simultaneously with controlled release of glaucocalyxin A (GLA). In this study, controlled release of GLA was achieved by the osmotic release strategy taking advantage of the bioavailability enhancing capacity of self-nanoemulsifying drug delivery systems (SNEDDS). The formulation of GLA-SNEDDS was selected by the solubility and pseudoternary-phase diagrams studies. The prepared GLA-SNEDDS formulations were characterized for self-emulsification time, effect of pH and robustness to dilution, droplet size analysis and zeta potential. The optimized GLA-SNEDDS were used to prepare GLA-SNEDDS osmotic pump tablet via direct powder compression method. The effect of formulation variables on the release characteristic was investigated. GLA-SNEDDS osmotic pump tablets were administered to beagle dogs and their pharmacokinetics were compared to GLA and GLA-SNEDDS as a control. In vitro drug release studies indicated that the GLA-SNEDDS osmotic pump tablet showed sustained release profiles with 90% released within 12 h. Pharmacokinetic study showed steady blood GLA with prolonged T max and mean residence time (MRT), and enhanced bioavailability for GLA-SNEDDS osmotic pump tablet. It was concluded that simultaneous controlling on GLA release and enhanced bioavailability had been achieved by a combination of osmotic pump tablet and SNEDDS.

  3. Controlled release of ibuprofen by meso–macroporous silica

    Energy Technology Data Exchange (ETDEWEB)

    Santamaría, E., E-mail: esthersantamaria@ub.edu; Maestro, A.; Porras, M.; Gutiérrez, J.M.; González, C.

    2014-02-15

    Structured meso–macroporous silica was successfully synthesized from an O/W emulsion using decane as a dispersed phase. Sodium silicate solution, which acts as a silica source and a poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (EO{sub 19}PO{sub 39}EO{sub 19}) denoted as P84 was used in order to stabilize the emulsion and as a mesopore template. The materials obtained were characterized through transmission electron microscopy (TEM), scanning electron microscopy (SEM), small-angle X-ray diffraction scattering (SAXS) and nitrogen adsorption–desorption isotherms. Ibuprofen (IBU) was selected as the model drug and loaded into ordered meso–macroporous materials. The effect of the materials’ properties on IBU drug loading and release was studied. The results showed that the loading of IBU increases as the macropore presence in the material is increased. The IBU adsorption process followed the Langmuir adsorption isotherm. A two-step release process, consisting of an initial fast release and then a slower release was observed. Macropores enhanced the adsorption capacity of the material; this was probably due to the fact that they allowed the drug to access internal pores. When only mesopores were present, ibuprofen was probably adsorbed on the mesopores close to the surface. Moreover, the more macropore present in the material, the slower the release behaviour observed, as the ibuprofen adsorbed in the internal pores had to diffuse along the macropore channels up to the surface of the material. The material obtained from a highly concentrated emulsion was functionalized with amino groups using two methods, the post-grafting mechanism and the co-condensation mechanism. Both routes improve IBU adsorption in the material and show good behaviour as a controlled drug delivery system. - Graphical abstract: Ibuprofen release profiles for the materials obtained from samples P84{sub m}eso (black diamonds), P84{sub 2}0% (white squares), P84{sub 5

  4. Controlled release of ibuprofen by meso–macroporous silica

    International Nuclear Information System (INIS)

    Santamaría, E.; Maestro, A.; Porras, M.; Gutiérrez, J.M.; González, C.

    2014-01-01

    Structured meso–macroporous silica was successfully synthesized from an O/W emulsion using decane as a dispersed phase. Sodium silicate solution, which acts as a silica source and a poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (EO 19 PO 39 EO 19 ) denoted as P84 was used in order to stabilize the emulsion and as a mesopore template. The materials obtained were characterized through transmission electron microscopy (TEM), scanning electron microscopy (SEM), small-angle X-ray diffraction scattering (SAXS) and nitrogen adsorption–desorption isotherms. Ibuprofen (IBU) was selected as the model drug and loaded into ordered meso–macroporous materials. The effect of the materials’ properties on IBU drug loading and release was studied. The results showed that the loading of IBU increases as the macropore presence in the material is increased. The IBU adsorption process followed the Langmuir adsorption isotherm. A two-step release process, consisting of an initial fast release and then a slower release was observed. Macropores enhanced the adsorption capacity of the material; this was probably due to the fact that they allowed the drug to access internal pores. When only mesopores were present, ibuprofen was probably adsorbed on the mesopores close to the surface. Moreover, the more macropore present in the material, the slower the release behaviour observed, as the ibuprofen adsorbed in the internal pores had to diffuse along the macropore channels up to the surface of the material. The material obtained from a highly concentrated emulsion was functionalized with amino groups using two methods, the post-grafting mechanism and the co-condensation mechanism. Both routes improve IBU adsorption in the material and show good behaviour as a controlled drug delivery system. - Graphical abstract: Ibuprofen release profiles for the materials obtained from samples P84 m eso (black diamonds), P84 2 0% (white squares), P84 5 0% (black triangles), P84 7

  5. Light Control of Insulin Release and Blood Glucose Using an Injectable Photoactivated Depot.

    Science.gov (United States)

    Sarode, Bhagyesh R; Kover, Karen; Tong, Pei Y; Zhang, Chaoying; Friedman, Simon H

    2016-11-07

    In this work we demonstrate that blood glucose can be controlled remotely through light stimulated release of insulin from an injected cutaneous depot. Human insulin was tethered to an insoluble but injectable polymer via a linker, which was based on the light cleavable di-methoxy nitrophenyl ethyl (DMNPE) group. This material was injected into the skin of streptozotocin-treated diabetic rats. We observed insulin being released into the bloodstream after a 2 min trans-cutaneous irradiation of this site by a compact LED light source. Control animals treated with the same material, but in which light was blocked from the site, showed no release of insulin into the bloodstream. We also demonstrate that additional pulses of light from the light source result in additional pulses of insulin being absorbed into circulation. A significant reduction in blood glucose was then observed. Together, these results demonstrate the feasibility of using light to allow for the continuously variable control of insulin release. This in turn has the potential to allow for the tight control of blood glucose without the invasiveness of insulin pumps and cannulas.

  6. Drug release control in delivery system for biodegradable polymer drugs by γ-radiation

    International Nuclear Information System (INIS)

    Yoshioka, Sumie; Azo, Yukio; Kojima, Shigeo

    1997-01-01

    Characterizations of the drug release from microsphere and hydrogel preparation made from biodegradable polymers were investigated aiming at development of a drug delivery system which allows an optimum drug delivery and the identification of the factors which control its delivery. Poly-lactic acid microspheres containing 10% of progesterone were produced from poly DL-lactic acid and exposed to γ-ray at 5-1000 kGy. And its glass transition temperature (Tg) was determined by differential scanning calorimetry. The temperature was gradually lowered with an increase in the dose of radiation. Tg of the microsphere exposed at 1000 kGy was lower by 10degC compared with the untreated one, showing that Tg control is possible without changing the size distribution of microsphere. Then, the amount of progesterone released from microsphere was determined. The release rate of the drug linearly increased with a square root of radiation time. These results indicate that the control of drug release rate is possible through controling the microsphere's Tg by γ-ray radiation. (M.N.)

  7. Electroactive crown ester-Cu2+ complex with in-situ modification at molecular beacon probe serving as a facile electrochemical DNA biosensor for the detection of CaMV 35s.

    Science.gov (United States)

    Zhan, Fengping; Liao, Xiaolei; Gao, Feng; Qiu, Weiwei; Wang, Qingxiang

    2017-06-15

    A novel electrochemical DNA biosensor has been facilely constructed by in-situ assembly of electroactive 4'-aminobenzo-18-crown-6-copper(II) complex (AbC-Cu 2+ ) on the free terminal of the hairpin-structured molecule beacon. The 3'-SH modified molecule beacon probe was first immobilized on the gold electrode (AuE) surface through self-assembly chemistry of Au-S bond. Then the crow ester of AbC was covalently coupled with 5'-COOH on the molecule beacon, and served as a platform to attach the Cu 2+ by coordination with ether bond (-O-) of the crown cycle. Thus, an electroactive molecule beacon-based biosensing interface was constructed. In comparison with conventional methods for preparation of electroactive molecule beacon, the approach presented in this work is much simpler, reagent- and labor-saving. Selectivity study shows that the in-situ fabricated electroactive molecule beacon remains excellent recognition ability of pristine molecule beacon probe to well differentiate various DNA fragments. The target DNA can be quantatively determined over the range from 0.10pM to 0.50nM. The detection limit of 0.060pM was estimated based on signal-to-noise ratio of 3. When the biosensor was applied for the detection cauliflower mosaic virus 35s (CaMV 35s) in soybean extraction samples, satisfactory results are achieved. This work opens a new strategy for facilely fabricating electrochemical sensing interface, which also shows great potential in aptasensor and immurosensor fabrication. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Modelling electro-active polymers with a dispersion-type anisotropy

    Science.gov (United States)

    Hossain, Mokarram; Steinmann, Paul

    2018-02-01

    We propose a novel constitutive framework for electro-active polymers (EAPs) that can take into account anisotropy with a chain dispersion. To enhance actuation behaviour, particle-filled EAPs become promising candidates nowadays. Recent studies suggest that particle-filled EAPs, which can be cured under an electric field during the manufacturing time, do not necessarily form perfect anisotropic composites, rather they create composites with dispersed chains. Hence in this contribution, an electro-mechanically coupled constitutive model is devised that considers the chain dispersion with a probability distribution function in an integral form. To obtain relevant quantities in discrete form, numerical integration over the unit sphere is utilized. Necessary constitutive equations are derived exploiting the basic laws of thermodynamics that result in a thermodynamically consistent formulation. To demonstrate the performance of the proposed electro-mechanically coupled framework, we analytically solve a non-homogeneous boundary value problem, the extension and inflation of an axisymmetric cylindrical tube under electro-mechanically coupled load. The results capture various electro-mechanical couplings with the formulation proposed for EAP composites.

  9. Controlled release from bilayer-decorated magnetoliposomes via electromagnetic heating.

    Science.gov (United States)

    Chen, Yanjing; Bose, Arijit; Bothun, Geoffrey D

    2010-06-22

    Nanoscale assemblies that can be activated and controlled through external stimuli represent a next stage in multifunctional therapeutics. We report the formation, characterization, and release properties of bilayer-decorated magnetoliposomes (dMLs) that were prepared by embedding small hydrophobic SPIO nanoparticles at different lipid molecule to nanoparticle ratios within dipalmitoylphosphatidylcholine (DPPC) bilayers. The dML structure was examined by cryogenic transmission electron microscopy and differential scanning calorimetry, and release was examined by carboxyfluorescein leakage. Nanoparticle heating using alternating current electromagnetic fields (EMFs) operating at radio frequencies provided selective release of the encapsulated molecule at low nanoparticle concentrations and under physiologically acceptable EMF conditions. Without radio frequency heating, spontaneous leakage from the dMLs decreased with increasing nanoparticle loading, consistent with greater bilayer stability and a decrease in the effective dML surface area due to aggregation. With radio frequency heating, the initial rate and extent of leakage increased significantly as a function of nanoparticle loading and electromagnetic field strength. The mechanism of release is attributed to a combination of bilayer permeabilization and partial dML rupture.

  10. Thermosensitive liposomes entrapping iron oxide nanoparticles for controllable drug release

    International Nuclear Information System (INIS)

    Tai, L-A; Wang, Y-C; Wang, Y-J; Yang, C-S; Tsai, P-J; Lo, L-W

    2009-01-01

    Iron oxide nanoparticles can serve as a heating source upon alternative magnetic field (AMF) exposure. Iron oxide nanoparticles can be mixed with thermosensitive nanovehicles for hyperthermia-induced drug release, yet such a design and mechanism may not be suitable for controllable drug release applications in which the tissues are susceptible to environmental temperature change such as brain tissue. In the present study, iron oxide nanoparticles were entrapped inside of thermosensitive liposomes for AMF-induced drug release while the environmental temperature was maintained at a constant level. Carboxyfluorescein was co-entrapped with the iron oxide nanoparticles in the liposomes as a model compound for monitoring drug release and environmental temperature was maintained with a water circulator jacket. These experiments have been successfully performed in solution, in phantom and in anesthetized animals. Furthermore, the thermosensitive liposomes were administered into rat forearm skeletal muscle, and the release of carboxylfluorescein triggered by the external alternative magnetic field was monitored by an implanted microdialysis perfusion probe with an on-line laser-induced fluorescence detector. In the future such a device could be applied to simultaneous magnetic resonance imaging and non-invasive drug release in temperature-sensitive applications.

  11. Controlled Release of Lysozyme from Double-Walled Poly(Lactide-Co-Glycolide (PLGA Microspheres

    Directory of Open Access Journals (Sweden)

    Rezaul H. Ansary

    2017-10-01

    Full Text Available Double-walled microspheres based on poly(lactide-co-glycolide (PLGA are potential delivery systems for reducing a very high initial burst release of encapsulated protein and peptide drugs. In this study, double-walled microspheres made of glucose core, hydroxyl-terminated poly(lactide-co-glycolide (Glu-PLGA, and carboxyl-terminated PLGA were fabricated using a modified water-in-oil-in-oil-in-water (w1/o/o/w2 emulsion solvent evaporation technique for the controlled release of a model protein, lysozyme. Microspheres size, morphology, encapsulation efficiency, lysozyme in vitro release profiles, bioactivity, and structural integrity, were evaluated. Scanning electron microscopy (SEM images revealed that double-walled microspheres comprising of Glu-PLGA and PLGA with a mass ratio of 1:1 have a spherical shape and smooth surfaces. A statistically significant increase in the encapsulation efficiency (82.52% ± 3.28% was achieved when 1% (w/v polyvinyl alcohol (PVA and 2.5% (w/v trehalose were incorporated in the internal and external aqueous phase, respectively, during emulsification. Double-walled microspheres prepared together with excipients (PVA and trehalose showed a better control release of lysozyme. The released lysozyme was fully bioactive, and its structural integrity was slightly affected during microspheres fabrication and in vitro release studies. Therefore, double-walled microspheres made of Glu-PLGA and PLGA together with excipients (PVA and trehalose provide a controlled and sustained release for lysozyme.

  12. Dielectric and polarization behaviour of cellulose electro-active paper (EAPap)

    International Nuclear Information System (INIS)

    Yun, Gyu-Young; Kim, Joo-Hyung; Kim, Jaehwan

    2009-01-01

    Dielectric and polarization behaviour of electro-active paper (EAPap) were studied to understand the detailed material behaviour of EAPap as a novel smart material. It was revealed that the dielectric constant of EAPap was temperature and frequency dependent. The largest change in the dielectric constant was observed near 0 0 C while the highest dielectric constant was obtained at around 100 0 C, which might be related to the dipolar behaviour of the hydroxyl structure of cellulose and adsorbed or existing internal water molecules in cellulose EAPap. By thermal stimulated current measurement for polarization behaviour of cellulose EAPap, it was shown that the maximum current was observed in the temperature range 105-110 0 C. Compared with the polarization behaviour in the low temperature range, abnormal polarization was observed under an applied field mainly due to the trapped space charge in EAPap, which indicates that cellulose EAPap has a similar material behaviour to that of electret polymers. (fast track communication)

  13. Control of drug releasing from biodegradable polymer drug delivery system by gamma-ray irradiation

    International Nuclear Information System (INIS)

    Yoshioka, Sumie; Aso, Yukio; Kojima, Shigeo

    1999-01-01

    In order to introduce the drug to the target organ, we developed a gel to control the drug releasing velocity by response to change of temperature by means of γ-ray irradiation to gelatin-GMA modified dextran mixture aqueous solution. A certain level of molecular weight of drug is necessary. The response to the temperature (change of drug releasing velocity) was affected by the concentration of gelatin and the modification rate of GMA. The Higuchi equation was applied to the releasing of β-galactosidase from gelatin-dextran gel and the releasing velocity was calculated. The releasing velocity decreased with increasing GMA modification rate at 37degC and 15degC. The releasing velocity of β-galactosidase decreased with increasing the concentration of gelatin at 15degC, but the velocity increased with increasing the concentration at 37degC. These results indicated that the good drug releasing conditions are obtained by controlling the GMA modification rate and the concentration of gelatin. (S.Y.)

  14. Production and Investigation of Controlled Drug Release Properties of Tamoxifen Loaded Alginate-Gum Arabic Microbeads

    Directory of Open Access Journals (Sweden)

    Rukiye Yavaşer

    2016-08-01

    Full Text Available The entrapment of tamoxifen onto alginate-gum arabic beads and the production of controlled drug release was investigated in this study. The polymeric system that would provide the controlled release of tamoxifen was formed using alginate and gum arabic. In the first phase of the study, the optimization of the alginate-gum arabic beads production was conducted; then the study continued with drug entrapment experiments. Tamoxifen entrapment yield was found to be approximately 90% of initial tamoxifen concentration. In vitro drug release experiments were performed in simulated gastric juice and intestinal fluid where the tamoxifen release was 20% and 53% of the initial drug present, respectively. As a result of this study, it is expected that a valuable contribution to the field of controlled drug release system production is realized.

  15. Design of a gastroretentive mucoadhesive dosage form of furosemide for controlled release

    Directory of Open Access Journals (Sweden)

    Sharad S. Darandale

    2012-10-01

    Full Text Available The aim of the present study was to develop and characterize a gastroretentive dosage form suitable for controlled drug release. It consists of a drug loaded polymeric film made up of a bilayer of immediate (IR and controlled release (CR layers folded into a hard gelatin capsule. Gastroretention results from unfolding and swelling of the film and its bioadhesion to the gastric mucosa. Furosemide, a drug with a narrow absorption window, was selected as the model drug. Inclusion of hydroxypropyl β-cyclodextrin in both layers and Carbopol® 971P NF in the CR layer of the bilayer film resulted in optimum drug release, bioadhesion and mechanical properties. The film with zig-zag folding in the capsule was shown to unfold and swell under acidic conditions and provide IR of drug over 1 h and CR for up to 12 h in acidic medium. X-ray diffraction, differential scanning calorimetry and scanning electron microscopy revealed uniform dispersion of furosemide in the polymeric matrices. The results indicate the dosage form is gastroretentive and can provide controlled release of drugs with narrow therapeutic windows.

  16. Solution combustion synthesis of calcium phosphate particles for controlled release of bovine serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Junfeng, E-mail: daidai02304@163.com [School of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu (China); Jiangsu Laboratory of Advanced Functional Materials, Changshu Institute of Technology, Changshu (China); Zhao, Junjie; Qian, Yu; Zhang, Xiali; Zhou, Feifei; Zhang, Hong [School of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu (China); Lu, Hongbin [National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, Nanjing University, Nanjing (China); Chen, JianHua; Wang, XuHong [School of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu (China); Jiangsu Laboratory of Advanced Functional Materials, Changshu Institute of Technology, Changshu (China); Yu, Wencong [School of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu (China)

    2015-05-01

    Four different phase compositions of calcium phosphate (CaP) particles were prepared via a solution combustion method. X-ray diffraction (XRD) and Rietveld analysis results revealed that the variations in the nominal Ca/P (molar) ratios were found to provide a favorable control in the different proportions of CaP materials. Bovine serum albumin (BSA) was used as a model protein to study the loading and release behavior. The release profile indicated that the BSA release rates depended on the phase compositions of the CaP particles, and showed an order of TCP-BSA > BCP-1-BSA > BCP-2-BSA > HA-BSA. The results suggested that the BSA protein release rate can be controlled by varying the phase compositions of CaP carriers. Moreover, the release process involved two stages: firstly surface diffusion via ion exchange and secondly intraparticle diffusion. - Highlights: • Solution combustion method was an efficient way to produced CaP powders. • Ca/P (molar) ratios provided a favorable control in the different proportions of phase composition. • BSA release rate varied depending on the phase composition of the CaP particles. • Two kinetic models were chosen to simulate the release kinetics of the drugs from CaP carriers.

  17. Electrorotation of novel electroactive polymer composites in uniform DC and AC electric fields

    International Nuclear Information System (INIS)

    Zrinyi, Miklós; Nakano, Masami; Tsujita, Teppei

    2012-01-01

    Novel electroactive polymer composites have been developed that could spin in uniform DC and AC electric fields. The angular displacement as well as rotation of polymer disks around an axis that is perpendicular to the direction of the applied electric field was studied. It was found that the dynamics of the polymer rotor is very complex. Depending on the strength of the static DC field, three regimes have been observed: no rotation occurs below a critical threshold field intensity, oscillatory motion takes place just above this value and continuous rotation can be observed above the critical threshold field intensity. It was also found that low frequency AC fields could also induce angular deformation. (paper)

  18. The Experiment of Carbofuran Controlled Release Formulation Insecticide Application on Rice Plants

    International Nuclear Information System (INIS)

    Sulistyati, M.; Ulfa TS; Sofnie M Ch; Kuswadi AN

    2004-01-01

    Field test of carbofuran insecticide (2,3-dihydro-2,2-dimethyl-7-benzofuranyl-N-methylcarbamate) controlled release formulation on rice plants of IR-64 variety was carried out in Pusakanegara, West Java. This insecticide formulation was made by using the mixture of activated charcoal, tapioca, kaolin, Na-alginate as a filler matrix. Insecticide formulation was applied one week after transplanting. The observations were conducted on the number of tillers, damage level caused by Orseolia oryzae (Wood/Mason), Chilo suppressalis (Walker), and Cnaphalocrosis medinalis (Guen) on new young plants. The observation were carried out on three weeks after application of carbofuran insecticide formulation then every two weeks until harvest. The number of tillers were occurred at the treatments of controlled release formulation of 20kg/ha, 30kg/ha, and 40kg/ha dose rate on the third weeks, it was showed significant difference compared with commercial carbofuran, and the following weeks were no significant difference between the treatments. The attack of Orseolia oryzae was occurred at the treatments of controlled release formulation with dose rate of 30 kg/ha and 40 kg/ha on the seventh weeks, ninth weeks, and eleventh weeks, those attacks were significantly difference found compared with commercial carbofuran. The attack of Chilo suppressalis was occurred at the treatments of controlled release formulation of 40kg/ha dose rate on the fifth weeks, it was showed significant difference which was compared to untreated carbofuran. The attack of Cnaphalocrosis medinalis was occurred on the ninth weeks, three dose rate of controlled released formulation were showed significant differences which compared with commercial carbofuran and were showed 50% less than commercial carbofuran, while the grains dry weight were no significant difference between the treatments. (author)

  19. Chitosan/alginate based multilayers to control drug release fromophthalmic lens

    OpenAIRE

    Silva, Diana; Pinto, Luís F. V.; Bozukova, Dimitriya; Santos, Luís F.; Serro, Ana Paula; Saramago, Benilde

    2016-01-01

    In this study we investigated the possibility of using layer-by-layer deposition, based in natural polymers (chitosan and alginate), to control the release of different ophthalmic drugs from three types of lens materials: a silicone-based hydrogel recently proposed by our group as drug releasing soft contact lens (SCL) material and two commercially available materials: CI26Y for intraocular lens (IOLs) and Definitive 50 for SCLs. The optimised coating, consisting in one double layer of (algin...

  20. A controlled release of ibuprofen by systematically tailoring the morphology of mesoporous silica materials

    International Nuclear Information System (INIS)

    Qu Fengyu; Zhu Guangshan; Lin Huiming; Zhang Weiwei; Sun Jinyu; Li Shougui; Qiu Shilun

    2006-01-01

    A series of mesoporous silica materials with similar pore sizes, different morphologies and variable pore geometries were prepared systematically. In order to control drug release, ibuprofen was employed as a model drug and the influence of morphology and pore geometry of mesoporous silica on drug release profiles was extensively studied. The mesoporous silica and drug-loaded samples were characterized by X-ray diffraction, Fourier transform IR spectroscopy, N 2 adsorption and desorption, scanning electron microscopy, and transmission electron microscopy. It was found that the drug-loading amount was directly correlated to the Brunauer-Emmett-Teller surface area, pore geometry, and pore volume; while the drug release profiles could be controlled by tailoring the morphologies of mesoporous silica carriers. - Graphical abstract: The release of ibuprofen is controlled by tailoring the morphologies of mesoporous silica. The mesoporous silica and drug-loaded samples are characterized by powder X-ray diffraction, Fourier transform IR spectroscopy, N 2 adsorption and desorption, scanning electron microscopy, and transmission electron microscopy. The drug-loading amount is directly correlated to the Brunauer-Emmett-Teller surface area, pore geometry, and pore volume; while the drug release profiles can be controlled by tailoring the morphologies of mesoporous silica carriers

  1. Experimental Physics and Industrial Control System (EPICS): Application source/release control for EPICS R3.11.6

    International Nuclear Information System (INIS)

    Zieman, B.; Kraimer, M.

    1994-01-01

    This manual describes a set of tools that can be used to develop software for EPICS based control systems. It provides the following features: Multiple applications; the entire system is composed of an arbitrary number of applications: Source/Release Control; all files created or modified by the applications developers can be put under sccs (a UNIX Source/Release control utility): Multiple Developers; it allows a number of applications developers to work separately during the development phase but combine their applications for system testing and for a production system; Makefiles: makefiles are provided to automatically rebuild various application components. For C and state notation programs, Imagefiles are provided

  2. Preparation and Characterization of Controlled-Release Avermectin/Castor Oil-Based Polyurethane Nanoemulsions.

    Science.gov (United States)

    Zhang, Hong; Qin, He; Li, Lingxiao; Zhou, Xiaoteng; Wang, Wei; Kan, Chengyou

    2017-06-12

    Avermectin (AVM) is a low-toxic and high-active biopesticide, but it can be easily degraded by UV light. In this paper, biodegradable castor oil-based polyurethanes (CO-PU) are synthesized and used as carriers to fabricate a new kind of AVM/CO-PU nanoemulsion through an emulsion solvent evaporation method, and the chemical structure, colloidal property, AVM loading capacity, controlled-release behavior, foliar adhesion, and photostability of the AVM/CO-PU drug delivery systems are investigated. Results show that AVM is physically encapsulated in the CO-PU carrier nanospheres, the diameter of the AVM/CO-PU nanoparticles is 85%. The release profiles indicate that the release rate is relatively high at the early stage and then slows, which can be adjusted by loaded AVM content, temperature, and pH of the release medium. The foliar pesticide retention of the AVM/CO-PU nanoemulsions is improved, and the photolysis rate of AVM in the AVM/CO-PU nanoparticles is significantly slower than that of the free AVM. A release mechanism of the AVM/CO-PU nanoemulsions is proposed, which is controlled by both diffusion and matrix erosion.

  3. Reinforced poly(propylene oxide)- a very soft and extensible dielectric electroactive polymer

    DEFF Research Database (Denmark)

    Goswami, Kaustav; Galantini, F.; Mazurek, Piotr Stanislaw

    2013-01-01

    Poly(propylene oxide) (PPO), a novel soft elastomeric material, and its composites were investigated as a new dielectric electroactive polymer (EAP). The PPO networks were obtained from thiol-ene chemistry by photochemical crosslinking of ,!-diallyl PPO with a tetra-functional thiol. The elastomer...... was reinforced with hexamethylenedisilazane treated fumed silica to improve the mechanical properties of PPO. The mechanical properties of PPO and composites thereof were investigated by shear rheology and stress–strain measurements. It was found that incorporation of silica particles improved the stability...... of the otherwise mechanically weak pure PPO network. Dielectric spectroscopy revealed high relative dielectric permittivity of PPO at 103 Hz of 5.6. The relative permittivity was decreased slightly upon addition of fillers, but remained higher than the commonly used acrylic EAP material VHB4910...

  4. Release from control of inactive material from decommissioning the ASTRA research reactor

    International Nuclear Information System (INIS)

    Brandl, A.; Hrnecek, E.; Steger, F.; Kurz, H.; Meyer, F.; Karacson, P.

    2003-01-01

    The Austrian Research Centers Seibersdorf have been operating a 10 MW ASTRA research reactor from 1960 until 1999. After that date, a submission of the intention to decommission the reactor has been provided to the Competent Authorities. After completion of an Environmental Impact Study by the Competent Authorities and modification of the Permissions for Site Use, the reactor finally entered the decommissioning phase in 2003. Inactive materials from the decommissioning site are expected to be released from control. The procedure for such a release from control agreed upon between the Competent Authorities and ARC Seibersdorf involves a four-step measurement, verification, and certification process detailed in this paper. By September 2003, this four-step procedure has been completed for 16500 kg of steel re-enforced concrete and for 5500 kg of other materials; the release from control of 3000 kg of paraffin and 10000 kg of graphite from the thermal column are planned for the near future. (author)

  5. Preparation and unique electrical behaviors of monodispersed hybrid nanorattles of metal nanocores with hairy electroactive polymer shells.

    Science.gov (United States)

    Cai, Tao; Zhang, Bin; Chen, Yu; Wang, Cheng; Zhu, Chun Xiang; Neoh, Koon-Gee; Kang, En-Tang

    2014-03-03

    A versatile template-assisted strategy for the preparation of monodispersed rattle-type hybrid nanospheres, encapsulating a movable Au nanocore in the hollow cavity of a hairy electroactive polymer shell (Au@air@PTEMA-g-P3HT hybrid nanorattles; PTEMA: poly(2-(thiophen-3-yl)ethyl methacrylate; P3HT: poly(3-hexylthiophene), was reported. The Au@silica core-shell nanoparticles, prepared by the modified Stöber sol-gel process on Au nanoparticle seeds, were used as templates for the synthesis of Au@silica@PTEMA core-double shell nanospheres. Subsequent oxidative graft polymerization of 3-hexylthiophene from the exterior surface of the Au@silica@PTEMA core-double shell nanospheres allowed the tailoring of surface functionality with electroactive P3HT brushes (Au@silica@PTEMA-g-P3HT nanospheres). The Au@air@ PTEMA-g-P3HT hybrid nanorattles were obtained after etching of the silica interlayer by HF. The as-prepared nanorattles were dispersed into an electrically insulating polystyrene matrix and for the first time used to fabricate nonvolatile memory devices. As a result, unique electrical behaviors, including insulator behavior, write-once-read-many-times and rewritable memory effects, and conductor behavior as well, were observed in the Al/Au@air@PTEMA-g-P3HT+PS/ITO (ITO: indium-tin oxide) sandwich thin-film devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Considerations for Contractile Electroactive Polymeric Materials and Actuators

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, Lenore; Erickson, Carl J.; Meixler, Lewis D.; Ascione, George; Gentile, Charles A.; Tilson, Charles; Bernasek, Stephen L.; Abelev, Esta

    2009-06-16

    Ras Labs produces electroactive polymer (EAP) based materials and actuators that bend, swell, ripple and now contract (new development) with low electric input. This is an important attribute because of the ability of contraction to produce life-like motion. The mechanism of contraction is not well understood. Radionuclide-labeled experiments were conducted to follow the movement of electrolytes and water in these EAPs when activated. Extreme temperature experiments were performed on the contractile EAPs with very favorable results. One of the biggest challenges in developing these actuators, however, is the electrode-EAP interface because of the pronounced movement of the EAP. Plasma treatments of metallic electrodes were investigated in order to improve the attachment of the embedded electrodes to the EAP material. Surface analysis, adhesive testing, and mechanical testing were conducted to test metal surfaces and metal-polymer interfaces. The nitrogen plasma treatment of titanium produced a strong metal-polymer interface; however, oxygen plasma treatment of both stainless steel and titanium produced even stronger metal-polymer interfaces. Plasma treatment of the electrodes allows for the embedded electrodes and the EAP material of the actuator to work and move as a unit, with no detachment, by significantly improving the metal-polymer interface.

  7. Considerations for Contractile Electroactive Polymeric Materials and Actuators

    International Nuclear Information System (INIS)

    Rasmussen, L.; Erickson, Carl J.; Meixler, Lewis D.; Ascione, G.; Gentile, Charles A.; Tilson, C.; Bernasek, Stephen L.; Abelev, E.

    2009-01-01

    Ras Labs produces electroactive polymer (EAP) based materials and actuators that bend, swell, ripple and now contract (new development) with low electric input. This is an important attribute because of the ability of contraction to produce life-like motion. The mechanism of contraction is not well understood. Radionuclide-labeled experiments were conducted to follow the movement of electrolytes and water in these EAPs when activated. Extreme temperature experiments were performed on the contractile EAPs with very favorable results. One of the biggest challenges in developing these actuators, however, is the electrode-EAP interface because of the pronounced movement of the EAP. Plasma treatments of metallic electrodes were investigated in order to improve the attachment of the embedded electrodes to the EAP material. Surface analysis, adhesive testing, and mechanical testing were conducted to test metal surfaces and metal-polymer interfaces. The nitrogen plasma treatment of titanium produced a strong metal-polymer interface; however, oxygen plasma treatment of both stainless steel and titanium produced even stronger metal-polymer interfaces. Plasma treatment of the electrodes allows for the embedded electrodes and the EAP material of the actuator to work and move as a unit, with no detachment, by significantly improving the metal-polymer interface

  8. Sensitive voltammetric detection of DNA damage at carbon electrodes using DNA repair enzymes and an electroactive osmium marker

    Czech Academy of Sciences Publication Activity Database

    Havran, Luděk; Vacek, Jan; Cahová, Kateřina; Fojta, Miroslav

    2008-01-01

    Roč. 391, č. 5 (2008), s. 1751-1758 ISSN 1618-2642 R&D Projects: GA AV ČR(CZ) IAA4004402; GA AV ČR(CZ) IAA400040611; GA ČR(CZ) GA203/07/1195; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : DNA damage * electroactive marker * carbon electrodes Subject RIV: BO - Biophysics Impact factor: 3.328, year: 2008

  9. Release of DNA from polyelectrolyte multilayers fabricated using 'charge-shifting' cationic polymers: tunable temporal control and sequential, multi-agent release.

    Science.gov (United States)

    Sun, Bin; Lynn, David M

    2010-11-20

    We report an approach to the design of multilayered polyelectrolyte thin films (or 'polyelectrolyte multilayers', PEMs) that can be used to provide tunable control over the release of plasmid DNA (or multiple different DNA constructs) from film-coated surfaces. Our approach is based upon methods for the layer-by-layer assembly of DNA-containing thin films, and exploits the properties of a new class of cationic 'charge-shifting' polymers (amine functionalized polymers that undergo gradual changes in net charge upon side chain ester hydrolysis) to provide control over the rates at which these films erode and release DNA. We synthesized two 'charge-shifting' polymers (polymers 1 and 2) containing different side chain structures by ring-opening reactions of poly(2-alkenyl azlactone)s with two different tertiary amine functionalized alcohols (3-dimethylamino-1-propanol and 2-dimethylaminoethanol, respectively). Subsequent characterization revealed large changes in the rates of side chain ester hydrolysis for these two polymers; whereas the half-life for the hydrolysis of the esters in polymer 1 was ~200 days, the half-life for polymer 2 was ~6 days. We demonstrate that these large differences in side chain hydrolysis make possible the design of PEMs that erode and promote the surface-mediated release of DNA either rapidly (e.g., over ~3 days for films fabricated using polymer 2) or slowly (e.g., over ~1 month for films fabricated using polymer 1). We demonstrate further that it is possible to design films with release profiles that are intermediate to these two extremes by fabricating films using solutions containing different mixtures of these two polymers. This approach can thus expand the usefulness of these two polymers and achieve a broader range of DNA release profiles without the need to synthesize polymers with new structures or properties. Finally, we demonstrate that polymers 1 and 2 can be used to fabricate multilayered films with hierarchical structures that

  10. Controlled Release Kinetics in Hydroxy Double Salts: Effect of Host Anion Structure

    Directory of Open Access Journals (Sweden)

    Stephen Majoni

    2014-01-01

    Full Text Available Nanodimensional layered metal hydroxides such as layered double hydroxides (LDHs and hydroxy double salts (HDSs can undergo anion exchange reactions releasing intercalated anions. Because of this, these metal hydroxides have found applications in controlled release delivery of bioactive species such as drugs and pesticides. In this work, isomers of hydroxycinnamate were used as model compounds to systematically explore the effects of anion structure on the rate and extent of anion release in HDSs. Following intercalation and subsequent release of the isomers, it has been demonstrated that the nature and position of substituent groups on intercalated anions have profound effects on the rate and extent of release. The extent of release was correlated with the magnitude of dipole moments while the rate of reaction showed strong dependence on the extent of hydrogen bonding within the layers. The orthoisomer showed a more sustained and complete release as compared to the other isomers.

  11. Using polymer-coated controlled-release fertilizers in the nursery and after outplanting

    Science.gov (United States)

    Thomas D. Landis; R. Kasten Dumroese

    2009-01-01

    Controlled-release fertilizers (CRF) are the newest and most technically advanced way of supplying mineral nutrients to nursery crops. Compared to conventional fertilizers, their gradual pattern of nutrient release better meets plant needs, minimizes leaching, and therefore improves fertilizer use efficiency. In our review of the literature, we found many terms used...

  12. Newly developed controlled release subcutaneous formulation for tramadol hydrochloride

    Directory of Open Access Journals (Sweden)

    Mostafa Mabrouk

    2018-05-01

    Full Text Available This study presents a drug delivery system of poly (Ɛ-caprolactone (PCL ribbons to optimize the pharmaceutical action of tramadol for the first time according to our knowledge. PCL ribbons were fabricated and loaded with tramadol HCl. Ribbons were prepared by slip casting technique and coated with dipping technique with β-cyclodextrin. The chemical integrity and surface morphology of the ribbons were confirmed using FTIR and SEM coupled with EDX. In addition, thermodynamic behavior of the fabricated ribbons was investigated using DSC/TGA. Tramadol loading into PCL ribbons, biodegradation of ribbons and tramadol release kinetics were studied in PBS.The results revealed that the formulated composition did not affect the chemical integrity of the drug. Furthermore, SEM/EDX confirmed the inclusion of tramadol into the PCL matrix in homogenous distribution pattern without any observation of porous structure. The particle size of loaded tramadol was found to be in the range of (2–4 nm. The formulated composition did not affect the chemical integrity of the drug and should be further investigated for bioavailability. Tramadol exhibited controlled release behavior from PCL ribbons up to 45 days governed mainly by diffusion mechanism. The fabricated ribbons have a great potentiality to be implemented in the long term subcutaneous delivery of tramadol. Keywords: Tramadol, Polycaprolcatone, Subcutaneous membrane, Ribbons, β-Cyclodextrin, Controlled release

  13. Tunable controlled release of molecular species from Halloysite nanotubes

    Science.gov (United States)

    Elumalai, Divya Narayan

    Encouraged by potential applications in rust coatings, self-healing composites, selective delivery of drugs, and catalysis, the transport of molecular species through Halloysite nanotubes (HNTs), specifically the storage and controlled release of these molecules, has attracted strong interest in recent years. HNTs are a naturally occurring biocompatible nanomaterial that are abundantly and readily available. They are alumosilicate based tubular clay nanotubes with an inner lumen of 15 nm and a length of 600-900 nm. The size of the inner lumen of HNTs may be adjusted by etching. The lumen can be loaded with functional agents like antioxidants, anticorrosion agents, flame-retardant agents, drugs, or proteins, allowing for a sustained release of these agents for hours. The release times can be further tuned for days and months by the addition of tube end-stoppers. In this work a three-dimensional, time-quantified Monte Carlo model that efficiently describes diffusion through and from nanotubes is implemented. Controlled delivery from Halloysite Nanotubes (HNT) is modeled based on interactions between the HNT's inner wall and the nanoparticles (NP) and among NPs themselves. The model was validated using experimental data published in the literature. The validated model is then used to study the effect of multiple parameters like HNT diameter and length, particle charge, ambient temperature and the creation of smart caps at the tube ends on the release of encapsulated NPs. The results show that release profiles depend on the size distribution of the HNT batch used for the experiment, as delivery is sensitive to HNT lumen and length. The effect of the addition of end-caps to the HNTs, on the rate of release of encapsulated NPs is also studied here. The results show that the release profiles are significantly affected by the addition of end caps to the HNTs and is sensitive to the end-cap pore lumen. A very good agreement with the experiment is observed when a weight

  14. Electrocoagulation of whey acids: anode and cathode materials, electroactive area and polarization curves

    Directory of Open Access Journals (Sweden)

    Francisco Prieto Garcia

    2017-06-01

    Full Text Available Anode (Al and Fe and cathode (graphite and Ti/RuO2 materials have been tested for electrocoagulation (EC and purification of the acid whey. The electroactive areas (EA of electrodes were calculated by the double layer capacitance method. Experiments were performed by cyclic voltammetry, chronoamperometry and polarization experiments. Among cathodic materials, the Ti/RuO2 electrode showed higher EA (2167 cm2 than graphite (1560 cm2. The Fe anode was found more stable than Al with greater charge transfer carried out in less time. Correlation of these results with those obtained during preliminary tests confirmed high removals (79 % in 8 h. For the Al electrode, 24 h were required to achieve efficiency of 49 %.

  15. Development of Process Analytical Technology (PAT) methods for controlled release pellet coating.

    Science.gov (United States)

    Avalle, P; Pollitt, M J; Bradley, K; Cooper, B; Pearce, G; Djemai, A; Fitzpatrick, S

    2014-07-01

    This work focused on the control of the manufacturing process for a controlled release (CR) pellet product, within a Quality by Design (QbD) framework. The manufacturing process was Wurster coating: firstly layering active pharmaceutical ingredient (API) onto sugar pellet cores and secondly a controlled release (CR) coating. For each of these two steps, development of a Process Analytical Technology (PAT) method is discussed and also a novel application of automated microscopy as the reference method. Ultimately, PAT methods should link to product performance and the two key Critical Quality Attributes (CQAs) for this CR product are assay and release rate, linked to the API and CR coating steps respectively. In this work, the link between near infra-red (NIR) spectra and those attributes was explored by chemometrics over the course of the coating process in a pilot scale industrial environment. Correlations were built between the NIR spectra and coating weight (for API amount), CR coating thickness and dissolution performance. These correlations allow the coating process to be monitored at-line and so better control of the product performance in line with QbD requirements. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Dual turn-on fluorescence signal-based controlled release system for real-time monitoring of drug release dynamics in living cells and tumor tissues.

    Science.gov (United States)

    Kong, Xiuqi; Dong, Baoli; Song, Xuezhen; Wang, Chao; Zhang, Nan; Lin, Weiying

    2018-01-01

    Controlled release systems with capabilities for direct and real-time monitoring of the release and dynamics of drugs in living systems are of great value for cancer chemotherapy. Herein, we describe a novel dual turn-on fluorescence signal-based controlled release system ( CDox ), in which the chemotherapy drug doxorubicin ( Dox ) and the fluorescent dye ( CH ) are conjugated by a hydrazone moiety, a pH-responsive cleavable linker. CDox itself shows nearly no fluorescence as the fluorescence of CH and Dox is essentially quenched by the C=N isomerization and N-N free rotation. However, when activated under acidic conditions, CDox could be hydrolyzed to afford Dox and CH , resulting in dual turn-on signals with emission peaks at 595 nm and 488 nm, respectively. Notably, CDox exhibits a desirable controlled release feature as the hydrolysis rate is limited by the steric hindrance effect from both the Dox and CH moieties. Cytotoxicity assays indicate that CDox shows much lower cytotoxicity relative to Dox , and displays higher cell inhibition rate to cancer than normal cells. With the aid of the dual turn-on fluorescence at different wavelengths, the drug release dynamics of CDox in living HepG2 and 4T-1 cells was monitored in double channels in a real-time fashion. Importantly, two-photon fluorescence imaging of CDox in living tumor tissues was also successfully performed by high-definition 3D imaging. We expect that the unique controlled release system illustrated herein could provide a powerful means to investigate modes of action of drugs, which is critical for development of much more robust and effective chemotherapy drugs.

  17. Controlled release of isoproturon, imidacloprid, and cyromazine from alginate-bentonite-activated carbon formulations.

    Science.gov (United States)

    Garrido-Herrera, F J; Gonzalez-Pradas, E; Fernandez-Pérez, M

    2006-12-27

    Different alginate-based systems of isoproturon, imidacloprid, and cyromazine have been investigated in order to obtain controlled release (CR) properties. The basic formulation [sodium alginate (1.50%), pesticide (0.30%), and water] was modified using different amounts of bentonite and activated carbon. The higher values of encapsulation efficiency corresponded to those formulations prepared with higher percentages of activated carbon, showing higher encapsulation efficiency values for isoproturon and imidacloprid than for cyromazine, which has a higher water solubility. The kinetic experiments of imidacloprid/isoproturon release in water have shown us that the release rate is higher in imidacloprid systems than in those prepared with isoproturon. Moreover, it can be deduced that the use of bentonite and/or activated carbon sorbents reduces the release rate of the isoproturon and imidacloprid in comparison with the technical product and with alginate formulation without modifying agents. The highest decrease in release rate corresponds to the formulations prepared with the highest percentage of activated carbon. The water uptake, permeability, and time taken for 50% of the active ingredient to be released into water, T50, were calculated to compare the formulations. On the basis of a parameter of an empirical equation used to fit the pesticide release data, the release of isoproturon and imidacloprid from the various formulations into water is controlled by a diffusion mechanism. The sorption capacity of the sorbents and the permeability of the formulations were the most important factors modulating pesticide release. Finally, a linear correlation of the T50 values and the content of activated carbon in formulations were obtained.

  18. Methodology for performing measurements to release material from radiological control

    International Nuclear Information System (INIS)

    Durham, J.S.; Gardner, D.L.

    1993-09-01

    This report describes the existing and proposed methodologies for performing measurements of contamination prior to releasing material for uncontrolled use at the Hanford Site. The technical basis for the proposed methodology, a modification to the existing contamination survey protocol, is also described. The modified methodology, which includes a large-area swipe followed by a statistical survey, can be used to survey material that is unlikely to be contaminated for release to controlled and uncontrolled areas. The material evaluation procedure that is used to determine the likelihood of contamination is also described

  19. On–off switch-controlled doxorubicin release from thermo- and pH-responsive coated bimagnetic nanocarriers

    Energy Technology Data Exchange (ETDEWEB)

    Hammad, Mohaned; Nica, Valentin; Hempelmann, Rolf, E-mail: r.hempelmann@mx.uni-saarland.de [Saarland University, Department of Physical Chemistry (Germany)

    2016-08-15

    A switch-controlled drug release system is designed by coating of core/shell bimagnetic nanoparticles with a pH- and thermo-responsive polymer shell, which can be used as hyperthermic agent, drug carrier, and for controlled release. Doxorubicin is loaded onto the surface of the last coating layer, and a high loading efficiency of 90.5 % is obtained. The nanocarriers are characterized by FTIR, dynamic light scattering, Zeta potential, TEM, In vitro hyperthermia, and vibrating sample magnetometry. The core/shell magnetic nanoparticles (Zn{sub 0.4}Co{sub 0.6}Fe{sub 2}O{sub 4}@Zn{sub 0.4}Mn{sub 0.6}Fe{sub 2}O{sub 4}) exhibit a superparamagnetic behavior with a saturation magnetization around 45.6 emu/g and a high specific absorption rate of up to 360 W/g. The in vitro drug release experiments confirm that only a small amount of doxorubicin is released at body temperature and physiological pH, whereas a high drug release is obtained at acidic tumor pH under hyperthermia conditions (43 °C). The functionalized core/shell bimagnetic nanocarriers facilitate controllable release of doxorubicin as an effect of induced thermo- and pH-responsiveness of the polymer when are subjected to a high-frequency alternating magnetic field at acidic pH; thereby the drug release rate is controlled using on–off cycles of the applied field.Graphical Abstract.

  20. Electro-Active Polymers (EAPs: A Promising Route to Design Bio-Organic/Bioinspired Platforms with on Demand Functionalities

    Directory of Open Access Journals (Sweden)

    Vincenzo Guarino

    2016-05-01

    Full Text Available Through recent discoveries and new knowledge among correlations between molecular biology and materials science, it is a growing interest to design new biomaterials able to interact—i.e., to influence, to guide or to detect—with cells and their surrounding microenvironments, in order to better control biological phenomena. In this context, electro-active polymers (EAPs are showing great promise as biomaterials acting as an interface between electronics and biology. This is ascribable to the highly tunability of chemical/physical properties which confer them different conductive properties for various applicative uses (i.e., molecular targeting, biosensors, biocompatible scaffolds. This review article is divided into three parts: the first one is an overview on EAPs to introduce basic conductivity mechanisms and their classification. The second one is focused on the description of most common processes used to manipulate EAPs in the form of two-dimensional (2D and three-dimensional (3D materials. The last part addresses their use in current applications in different biomedical research areas including tissue engineering, biosensors and molecular delivery.

  1. Preliminary evaluation of an aqueous wax emulsion for controlled-release coating.

    Science.gov (United States)

    Walia, P S; Stout, P J; Turton, R

    1998-02-01

    The purpose of this work was to evaluate the use of an aqueous carnauba wax emulsion (Primafresh HS, Johnson Wax) in a spray-coating process. This involved assessing the effectiveness of the wax in sustaining the release of the drug, theophylline. Second, the process by which the drug was released from the wax-coated pellets was modeled. Finally, a method to determine the optimum blend of pellets with different wax thicknesses, in order to yield a zero-order release profile of the drug, was addressed. Nonpareil pellets were loaded with theophylline using a novel powder coating technique. These drug-loaded pellets were then coated with different levels of carnauba wax in a 6-in. diameter Plexiglas fluid bed with a 3.5-in. diameter Wurster partition. Drug release was measured using a spin-filter dissolution device. The study resulted in continuous carnauba wax coatings which showed sustained drug release profile characteristics typical of a barrier-type, diffusion-controlled system. The effect of varying wax thickness on the release profiles was investigated. It was observed that very high wax loadings would be required to achieve long sustained-release times. The diffusion model, developed to predict the release of the drug, showed good agreement with the experimental data. However, the data exhibited an initial lag-time for drug release which could not be predicted a priori based on the wax coating thickness. A method of mixing pellets with different wax thicknesses was proposed as a way to approximate zero-order release.

  2. Doses of controlled-release fertilizer for production of rubber tree rootstocks

    Directory of Open Access Journals (Sweden)

    Renato Luis Grisi Macedo

    2012-06-01

    Full Text Available This experimental study aimed to evaluate the effects of doses of controlled-release fertilizer (ALL on the development of rubber tree rootstocks. The fertilizer used was Osmocote®, scheduled to be released for 8-9 months and with the following composition: N (15%, P2O5 (9%, K2O (12%, Mg (1%, S (2.3%, B (0.02%, Cu (0.05%, Fe (1%, Mn (0.06%, Mo (0.02% and Zn (0.05%. A randomized block design was used, with four treatments and eight replicates of 20 plants per plot. The controlled-release fertilizer was added to Rendimax Floreira® substrate at doses of 0, 3, 6 and 9 g per liter, and rootstocks were produced in plastic containers with a capacity of two liters of substrate. Three seeds of clone GT 1 were scattered in each container and thinning was performed on day 60, leaving the most vigorous plant only. After the fourth leaf shot from each rootstock, the containers of each treatment were topped, due to compaction, with 300 mL of the relevant fertilizer and substrate mixture. The rootstocks were evaluated at eight months of age as to height, stem diameter (DC 5 cm above root collar, total dry matter, shoot and root dry matter, leaf nutrient levels and percentage of plants suitable for grafting (DC≥1.0 cm. Results revealed that adequate development and nutrition of rootstocks was achieved by using 6 g of controlled-release fertilizer per liter of substrate.

  3. Controlled release of ibuprofen by meso-macroporous silica

    Science.gov (United States)

    Santamaría, E.; Maestro, A.; Porras, M.; Gutiérrez, J. M.; González, C.

    2014-02-01

    Structured meso-macroporous silica was successfully synthesized from an O/W emulsion using decane as a dispersed phase. Sodium silicate solution, which acts as a silica source and a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (EO19PO39EO19) denoted as P84 was used in order to stabilize the emulsion and as a mesopore template. The materials obtained were characterized through transmission electron microscopy (TEM), scanning electron microscopy (SEM), small-angle X-ray diffraction scattering (SAXS) and nitrogen adsorption-desorption isotherms. Ibuprofen (IBU) was selected as the model drug and loaded into ordered meso-macroporous materials. The effect of the materials’ properties on IBU drug loading and release was studied. The results showed that the loading of IBU increases as the macropore presence in the material is increased. The IBU adsorption process followed the Langmuir adsorption isotherm. A two-step release process, consisting of an initial fast release and then a slower release was observed. Macropores enhanced the adsorption capacity of the material; this was probably due to the fact that they allowed the drug to access internal pores. When only mesopores were present, ibuprofen was probably adsorbed on the mesopores close to the surface. Moreover, the more macropore present in the material, the slower the release behaviour observed, as the ibuprofen adsorbed in the internal pores had to diffuse along the macropore channels up to the surface of the material. The material obtained from a highly concentrated emulsion was functionalized with amino groups using two methods, the post-grafting mechanism and the co-condensation mechanism. Both routes improve IBU adsorption in the material and show good behaviour as a controlled drug delivery system.

  4. Simulation and parametric study of a film-coated controlled-release pharmaceutical.

    Science.gov (United States)

    Borgquist, Per; Zackrisson, Gunnar; Nilsson, Bernt; Axelsson, Anders

    2002-04-23

    Pharmaceutical formulations can be designed as Multiple Unit Systems, such as Roxiam CR, studied in this work. The dose is administrated as a capsule, which contains about 100 individual pellets, which in turn contain the active drug remoxipride. Experimental data for a large number of single pellets can be obtained by studying the release using microtitre plates. This makes it possible to study the release of the individual subunits making up the total dose. A mathematical model for simulating the release of remoxipride from single film-coated pellets is presented including internal and external mass transfer hindrance apart from the most important film resistance. The model can successfully simulate the release of remoxipride from single film-coated pellets if the lag phase of the experimental data is ignored. This was shown to have a minor influence on the release rate. The use of the present model is demonstrated by a parametric study showing that the release process is film-controlled, i.e. is limited by the mass transport through the polymer coating. The model was used to fit the film thickness and the drug loading to the experimental release data. The variation in the fitted values was similar to that obtained in the experiments.

  5. Reducing Runoff Loss of Applied Nutrients in Oil Palm Cultivation Using Controlled-Release Fertilizers

    Directory of Open Access Journals (Sweden)

    A. Bah

    2014-01-01

    Full Text Available Controlled-release fertilizers are expected to minimize nutrient loss from crop fields due to their potential to supply plant-available nutrients in synchrony with crop requirements. The evaluation of the efficiency of these fertilizers in tropical oil palm agroecological conditions is not yet fully explored. In this study, a one-year field trial was conducted to determine the impact of fertilization with water soluble conventional mixture and controlled-release fertilizers on runoff loss of nutrients from an immature oil palm field. Soil and nutrient loss were monitored for one year in 2012/2013 under erosion plots of 16 m2 on 10% slope gradient. Mean sediments concentration in runoff amounted to about 6.41 t ha−1. Conventional mixture fertilizer posed the greatest risk of nutrient loss in runoff following fertilization due to elevated nitrogen (6.97%, potassium (13.37%, and magnesium (14.76% as percentage of applied nutrients. In contrast, this risk decreased with the application of controlled-release fertilizers, representing 0.75–2.44% N, 3.55–5.09% K, and 4.35–5.43% Mg loss. Meanwhile, nutrient loss via eroded sediments was minimal compared with loss through runoff. This research demonstrates that the addition of controlled-release fertilizers reduced the runoff risks of nutrient loss possibly due to their slow-release properties.

  6. Modelling approach for biological control of insect pest by releasing infected pest

    International Nuclear Information System (INIS)

    Tan Yuanshun; Chen Lansun

    2009-01-01

    Models of biological control have a long history of theoretical development that have focused on the interactions between a predator and a prey. Here we have extended the classical epidemic model to include a continuous and impulsive pest control strategies by releasing the infected pests bred in laboratory. For the continuous model, the results imply that the susceptible pest goes to extinct if the threshold condition R 0 0 > 1, the positive equilibrium of continuous model is globally asymptotically stable. Similarly, the threshold condition which guarantees the global stability of the susceptible pest-eradication periodic solution is obtained for the model with impulsive control strategy. Consequently, based on the results obtained in this paper, the control strategies which maintain the pests below an acceptably low level are discussed by controlling the release rate and impulsive period. Finally, the biological implications of the results and the efficiency of two control strategies are also discussed

  7. Studies for improvement of regulatory control on the radioactive effluent released from nuclear facilities

    International Nuclear Information System (INIS)

    Cheong, Jae Hak; Park, H. M.; Song, M. C.; Lee, K. H.; Jang, J. K.; Chun, J. K.; Jeong, K. H.

    2005-05-01

    This report contains the second-year results of the research project titled 'Studies for Improvement of Regulatory Control on the Radioactive Effluent Released from Nuclear Facilities' and mainly provides technical and strategic approaches to improve performance of regulatory control on the gaseous effluent released from domestic nuclear facilities. The main result contained here includes overview and technical bases of radioactive gaseous effluent control (Chapter 1), reconsideration of the sensitivity requirements for measurement of radioactivity in gaseous effluent sample (Chapter 2), uncertainty analysis of the calculated radioactivity in gaseous effluent (Chapter 3), and improvement of quantification method of noble gas releases (Chapter 4). In addition, analysis of the impact due to combined sampling of particulate from multiple release points (Chapter 5), comparison of domestic nuclear reactors gaseous effluent data to foreign PWRs (Chapter 6), standardized sampling technique for collection of gaseous tritium (Chapter 7), and application of Xe-133 equivalent concept to gaseous effluent control (Chapter 8) are also provided. As a whole, this report provides a generic approach to improve the performance of regulatory control on the gaseous effluent. Therefore, actual enforcement of the recommendations should be preceded by establishment of a series of action plans reflecting on the site- and facility-specific design and operational features

  8. Mechanical stretching effect on the actuator performance of cellulose electroactive paper

    International Nuclear Information System (INIS)

    Kim, Jung-Hwan; Yun, Ki-Ju; Kim, Joo-Hyung; Kim, Jaehwan

    2009-01-01

    The mechanical stretching effect on the actuating performance of electroactive cellulose paper (EAPap) was studied. A lattice elongation of cellulose fibrils due to in-plane tensile stress along the stretching direction was observed by the x-ray diffraction method. The shrinkage of the fibril diameter as a function of stretching ratio was confirmed by surface and cross-sectional images. While the actuator performance in terms of bending displacement decreased as the stretching ratio increased, the resonance frequency linearly increased as the stretching ratio increased, which was compared with the theoretical frequency data found from a cantilever beam model. The actuator efficiency was evaluated from the electrical input power consumption and the mechanical output power of an EAPap actuator. It was revealed that the stretching process increased the electro-mechanical efficiency of the EAPap actuator. The mechanism of the influence of the stretching effect on the performance of an EAPap actuator is discussed

  9. Development of artificial muscles based on electroactive ionomeric polymer-metal composites.

    Science.gov (United States)

    Hirano, Laos A; Escote, Márcia T; Martins-Filho, Luiz S; Mantovani, Gerson L; Scuracchio, Carlos H

    2011-05-01

    This work contextualizes the research of materials that can be applied as artificial muscles. The main motivation of this research is the importance of the development of mechatronic systems for the replacement of traditional devices of actuation and motion based on rotational electrical motors by other devices that reproduce biological muscle movements. Electroactive polymers (EAPs) are materials that respond to electric stimuli with shape and/or dimension changes, and accomplish movements that are smooth enough to mimic biological muscles. Among EAPs, the ionomeric polymer-metal composites (IPMCs) are an interesting alternative to biomimetic devices due to large displacements when submitted to low applied voltage. This article presents a brief review of IPMCs, a sample preparation procedure, and some electromechanical experimental results. We also discuss the applicability of this technology in medical devices and as artificial muscles. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  10. Development of controlled release formulations of azadirachtin-A employing poly(ethylene glycol) based amphiphilic copolymers.

    Science.gov (United States)

    Kumar, Jitendra; Shakil, Najam A; Singh, Manish K; Singh, Mukesh K; Pandey, Alka; Pandey, Ravi P

    2010-05-01

    Controlled release (CR) formulations of azadirachtin-A, a bioactive constituent derived from the seed of Azadirachta indica A. Juss (Meliaceae), have been prepared using commercially available polyvinyl chloride, polyethylene glycol (PEG) and laboratory synthesized poly ethylene glycol-based amphiphilic copolymers. Copolymers of polyethylene glycol and various dimethyl esters, which self assemble into nano micellar aggregates in aqueous media, have been synthesized. The kinetics of azadirachtin-A, release in water from the different formulations was studied. Release from the commercial polyethylene glycol (PEG) formulation was faster than the other CR formulations. The rate of release of encapsulated azadirachtin-A from nano micellar aggregates is reduced by increasing the molecular weight of PEG. The diffusion exponent (n value) of azadirachtin-A, in water ranged from 0.47 to 1.18 in the tested formulations. The release was diffusion controlled with a half release time (t(1/2)) of 3.05 to 42.80 days in water from different matrices. The results suggest that depending upon the polymer matrix used, the application rate of azadirachtin-A can be optimized to achieve insect control at the desired level and period.

  11. Nanostructural control of the release of macromolecules from silica sol–gels

    Science.gov (United States)

    Radin, Shula; Bhattacharyya, Sanjib; Ducheyne, Paul

    2013-01-01

    The therapeutic use of biological molecules such as growth factors and monoclonal antibodies is challenging in view of their limited half-life in vivo. This has elicited the interest in delivery materials that can protect these molecules until released over extended periods of time. Although previous studies have shown controlled release of biologically functional BMP-2 and TGF-β from silica sol–gels, more versatile release conditions are desirable. This study focuses on the relationship between room temperature processed silica sol–gel synthesis conditions and the nanopore size and size distribution of the sol–gels. Furthermore, the effect on release of large molecules with a size up to 70 kDa is determined. Dextran, a hydrophilic polysaccharide, was selected as a large model molecule at molecular sizes of 10, 40 and 70 kDa, as it enabled us to determine a size effect uniquely without possible confounding chemical effects arising from the various molecules used. Previously, acid catalysis was performed at a pH value of 1.8 below the isoelectric point of silica. Herein the silica synthesis was pursued using acid catalysis at either pH 1.8 or 3.05 first, followed by catalysis at higher values by adding base. This results in a mesoporous structure with an abundance of pores around 3.5 nm. The data show that all molecular sizes can be released in a controlled manner. The data also reveal a unique in vivo approach to enable release of large biological molecules: the use more labile sol–gel structures by acid catalyzing above the pH value of the isoelectric point of silica; upon immersion in a physiological fluid the pores expand to reach an average size of 3.5 nm, thereby facilitating molecular out-diffusion. PMID:23643607

  12. Design of a controlled release liquid formulation of lamotrigine

    Directory of Open Access Journals (Sweden)

    V Kumar

    2011-05-01

    Full Text Available "n  "n  Background and the purpose of the study: Lamotrigine is a broad spectrum anticonvulsant drug widely used as mono- or adjunct- therapy in adults and children. The aim of this study was to develop controlled release liquid formulation of lamotrigine to improve bioavailability and compliance of pediatric and geriatric epileptic patients. "n  Methods: Multiple (w/o/w emulsion was prepared using one step emulsification technique. It was evaluated for entrapment efficiency (EE, morphology, zeta potential (ZP, polydispersity index (PI, rheology, thermal property, in vitro drug release behavior and stability. In vivo studies in albino mice were carried out using maximal electroshock seizure (MES test and strychnine induced seizure (SIS pattern test and results were compared with marketed formulation. "n  Results: The EE of the formulations varied from 84.37% to 98.11%. The ZP and PI values of the prepared batches were in the range of +23.46 to +28.07 and 0.256 and 0.365, respectively. Microscopic observation clearly indicated the stability of the emulsions during the storage period. All batches exhibited controlled in vitro drug release up to 12 hrs. Batch C11 exhibited significantly longer duration of protection of seizure in mice against MES and exhibited comparable efficacy in SIS as compared to the marketed formulation. "n  Major Conclusion: Multiple emulsion of lamotrigine compared to the marketed tablet showed plasma drug concentration within therapeutic range for longer time and comparable efficacy.

  13. Thermo-responsive polymer-functionalized mesoporous carbon for controlled drug release

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Shenmin, E-mail: smzhu@sjtu.edu.cn [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Chen Chenxin [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Chen Zhixin [Faculty of Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Liu Xinye; Li Yao; Shi Yang; Zhang Di [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

    2011-03-15

    Research highlights: {yields} A responsive drug delivery system based on poly(N-isopropyl acrylamide) (PNIPAM) functionalized ordered mesoporous carbon (CMK-3) is developed. {yields} A combination of surface modification of CMK-3 and in situ internal polymerization of PNIPAM was used. {yields} The system exhibited a pronounced transition at around 20-25 deg. C. - Abstract: A novel responsive drug delivery system based on poly(N-isopropyl acrylamide) (PNIPAM) functionalized ordered mesoporous carbon (CMK-3) is developed. The polymer-functionalized CMK-3 was obtained by a combination of simple surface modification of CMK-3 and in situ internal polymerization of PNIPAM. The formation of the PNIPAM inside the CMK-3 was confirmed by thermal gravimetric analysis, Fourier transform-infrared spectroscopy, scanning and transmission electron microscopy and N{sub 2} adsorption/desorption measurements. Controlled drug release tests through the porous network of the PNIPAM functionalized CMK-3 were carried out by measuring the uptake and release of ibuprofen in vitro. The release profiles exhibited a pronounced transition at around 20-25 deg. C. This thermo-sensitive release property of this delivery system was further confirmed by temperature-variable hydrogen nuclear magnetic resonance analysis. The internal PNIPAM layers acted as a storage gate as well as a release switch in response to the stimuli of environment.

  14. CONTROLLED RELEASE, BLIND TEST OF DNAPL REMEDIATION BY ETHANOL FLUSHING

    Science.gov (United States)

    A dense nonaqueous phase liquid (DNAPL) source zone was established within a sheet-pileisolated cell through a controlled release of perchloroethylene (PCE) to evaluate DNAPLremediation by in-situ cosolvent flushing. Ethanol was used as the cosolvent, and the main remedia...

  15. Effluent release limits, sources and control

    International Nuclear Information System (INIS)

    Swindell, G.E.

    1977-01-01

    Objectives of radiation protection in relation to releases. Environmental transfer models for radionuclides. Relationship between releases, environmental levels and doses to persons. Establishment of release limits: Limits based on critical population group concept critical pathway analysis and identification of critical group. Limits based on optimization of radiation protection individual dose limits, collective doses and dose commitments 1) differential cost benefit analysis 2) authorized and operational limits taking account of future exposures. Monitoring of releases to the environment: Objectives of effluent monitoring. Typical sources and composition of effluents; design and operation of monitoring programmes; recording and reporting of monitoring results; complementary environmental monitoring. (orig.) [de

  16. Antifouling composites with self-adaptive controlled release based on an active compound intercalated into layered double hydroxides

    Science.gov (United States)

    Yang, Miaosen; Gu, Lianghua; Yang, Bin; Wang, Li; Sun, Zhiyong; Zheng, Jiyong; Zhang, Jinwei; Hou, Jian; Lin, Cunguo

    2017-12-01

    This paper reports a novel method to prepare the antifouling composites with properties of self-adaptive controlled release (defined as control the release rate autonomously and adaptively according to the change of environmental conditions) by intercalation of sodium paeonolsilate (PAS) into MgAl and ZnAl layered double hydroxide (LDH) with the molar ratio (M2+/M3+) of 2:1 and 3:1, respectively. The powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) confirm the intercalation of PAS into the galleries of LDH. The controlled release behavior triggered by temperature for the PAS-LDH composites has been investigated, and the results show that the release rate of all PAS-LDH composites increases as the increase of temperature. However, the MgAl-PAS-LDH composites (Mg2Al-PAS-LDH and Mg3Al-PAS-LDH) exhibit the increased release rate of 0.21 ppm/°C from 15 to 30 °C in 3.5% NaCl solution, more than three times of the ZnAl-PAS-LDH composites (0.06 ppm/°C), owing to the confined microenvironment influenced by metal types in LDH layers. In addition, a possible diffusion-controlled process with surface diffusion, bulk diffusion and heterogeneous flat surface diffusion has been revealed via fitting four kinetic equations. Moreover, to verify the practical application of the PAS-LDH composites, a model coating denoted as Mg2Al-PAS-LDH coating was fabricated. The release result displays that the release rate increases or decreases as temperature altered at 15 and 25 °C alternately, indicating its self-adaptive controlled release behavior with temperature. Moreover, the superior resistance to the settlement of Ulva spores at 15 and 25 °C was observed for the Mg2Al-PAS-LDH coating, as a result of the controllable release of antifoulant. Therefore, this work provides a facile and effective method for the fabrication of antifouling composites with self-adaptive controlled release behavior in response to temperature, which can be used to prolong

  17. Research and development of controlled release technology for agrochemicals using isotopes

    International Nuclear Information System (INIS)

    1986-01-01

    In recent years, increasing investment has been made into development of measures to reduce pesticide contamination of food and the environment while at the same time protecting crops and livestock from pest attack. Studies to develop controlled-release technology are frequently carried out with labelled compounds. Radiotracer techniques provide a unique tool in measuring the release rate of the chemical, the stability of the chemical within the formulation and evaluating the effect of environmental factors on the release rate. These technologies and pesticide residue problems were the theme of the Seminar. The Seminar has illustrated the potential value of isotope techniques and has reviewed information on current developments in this field and their relevance to agriculture in developing countries

  18. Preparation and Characterization of Conducting Polymer Latices by Chemical Polymerization of Aniline or Anisidine in Presence of Latex: Study of Their Electroactivity and Anti-Corrosion Properties

    Directory of Open Access Journals (Sweden)

    Bakhshali Massoumi

    2013-06-01

    Full Text Available Poly (vinylacetate-co-butylmethacrylate was prepared in presence of potassium persulphate as an oxidizing agent in aqueous solution of dodecylbenzene sulfonate sodium as an emulsifying agent. Then, aniline was polymerized by chemical oxidation method at three different concentrations of aniline monomer (0.1, 0.2 and 0.3 M in toluene in presence of poly(vinylacetate-co-butylmethacrylate in order to obtain polyaniline/poly(vinylacetate-co-butylmethacrylate. To prepare conducting-latex of polyanisidine/poly(vinylacetate-co-butylmethacrylate the same method was employed as above for aniline monomer in obtaining conducting polyaniline/poly(vinylacetate-co-butylmethacrylate latex. In addition, the purification of conducting-latex polymers, polyaniline/poly(vinylacetate-co-butylmethacrylate and polyanisidine/poly(vinylacetate-co-butylmethacrylate was conducted and preparation of tin layer films of conducting-latex polymers was carried out by casting method on glassy lames. The electroactivity properties of the prepared latex-polymers, polyaniline/poly(vinylacetate-co-butylmethacrylate and polyanisidine/poly(vinylacetate-co-butylmethacrylate were investigated by cyclic voltammetery (CV. The voltamogrames showed that the latex films were electroactive. Because of conductivity and electroactivity, the obtained films may find applications in anti-corrosion coatings. The anti-corrosion properties of conducting-latex polymers were studied on aluminum surface by impedance technique. The structure of the prepared conducting-latex polymers was confirmed by Fourier transform infrared (FTIR. Finally, the electrical conductivity of synthesized conducting-latex polymers, polyaniline/poly(vinylacetate-co-butylmethacrylate and polyanisidine/poly(vinylacetate-co-butylmethacrylate was measured by four probe technique.

  19. Development of controlled drug release systems based on thiolated polymers.

    Science.gov (United States)

    Bernkop-Schnürch, A; Scholler, S; Biebel, R G

    2000-05-03

    The purpose of the present study was to generate mucoadhesive matrix-tablets based on thiolated polymers. Mediated by a carbodiimide, L-cysteine was thereby covalently linked to polycarbophil (PCP) and sodium carboxymethylcellulose (CMC). The resulting thiolated polymers displayed 100+/-8 and 1280+/-84 micromol thiol groups per gram, respectively (means+/-S.D.; n=6-8). In aqueous solutions these modified polymers were capable of forming inter- and/or intramolecular disulfide bonds. The velocity of this process augmented with increase of the polymer- and decrease of the proton-concentration. The oxidation proceeded more rapidly within thiolated PCP than within thiolated CMC. Due to the formation of disulfide bonds within thiol-containing polymers, the stability of matrix-tablets based on such polymers could be strongly improved. Whereas tablets based on the corresponding unmodified polymer disintegrated within 2 h, the swollen carrier matrix of thiolated CMC and PCP remained stable for 6.2 h (mean, n=4) and more than 48 h, respectively. Release studies of the model drug rifampicin demonstrated that a controlled release can be provided by thiolated polymer tablets. The combination of high stability, controlled drug release and mucoadhesive properties renders matrix-tablets based on thiolated polymers useful as novel drug delivery systems.

  20. Aerial release of Rhinoncomimus latipes (Coleoptera: Curculionidae) to control Persicaria perfoliata (Polygonaceae) using an unmanned aerial system.

    Science.gov (United States)

    Park, Yong-Lak; Gururajan, Srikanth; Thistle, Harold; Chandran, Rakesh; Reardon, Richard

    2018-01-01

    Rhinoncomimus latipes (Coleoptera: Curculionidae) is a major biological control agent against the invasive plant Persicaria perfoliata. Release of R. latipes is challenging with the current visit-and-hand release approach because P. perfoliata shows a high degree of patchiness in the landscape, possesses recurved barbs on its stems, and often spreads into hard-to-access areas. This 3-year study developed and evaluated unmanned aerial systems (UAS) for precise aerial release of R. latipes to control P. perfoliata. We have developed two UAS (i.e. quad-rotor and tri-rotor) and an aerial release system to disseminate R. latipes. These include pods containing R. latipes and a dispenser to accommodate eight pods. Results of field tests to evaluate the systems showed no significant (P > 0.05) effects on survivorship and feeding ability of R. latipes after aerial release. Our study demonstrates the potential of UAS for precision aerial release of biological control agents to control invasive plants. The aerial deployment systems we have developed, including both pods and a dispenser, are low cost, logistically practical, and effective with no negative effects on aerially released R. latipes. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  1. Multi-Drug-Loaded Microcapsules with Controlled Release for Management of Parkinson's Disease.

    Science.gov (United States)

    Baek, Jong-Suep; Choo, Chee Chong; Qian, Cheng; Tan, Nguan Soon; Shen, Zexiang; Loo, Say Chye Joachim

    2016-07-01

    Parkinson's disease (PD) is a progressive disease of the nervous system, and is currently managed through commercial tablets that do not sufficiently enable controlled, sustained release capabilities. It is hypothesized that a drug delivery system that provides controlled and sustained release of PD drugs would afford better management of PD. Hollow microcapsules composed of poly-l-lactide (PLLA) and poly (caprolactone) (PCL) are prepared through a modified double-emulsion technique. They are loaded with three PD drugs, i.e., levodopa (LD), carbidopa (CD), and entacapone (ENT), at a ratio of 4:1:8, similar to commercial PD tablets. LD and CD are localized in both the hollow cavity and PLLA/PCL shell, while ENT is localized in the PLLA/PCL shell. Release kinetics of hydrophobic ENT is observed to be relatively slow as compared to the other hydrophilic drugs. It is further hypothesized that encapsulating ENT into PCL as a surface coating onto these microcapsules can aid in accelerating its release. Now, these spray-coated hollow microcapsules exhibit similar release kinetics, according to Higuchi's rate, for all three drugs. The results suggest that multiple drug encapsulation of LD, CD, and ENT in gastric floating microcapsules could be further developed for in vivo evaluation for the management of PD. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. A modified SILCS contraceptive diaphragm for long-term controlled release of the HIV microbicide dapivirine.

    Science.gov (United States)

    Major, Ian; Boyd, Peter; Kilbourne-Brook, Maggie; Saxon, Gene; Cohen, Jessica; Malcolm, R Karl

    2013-07-01

    There is considerable interest in developing new multipurpose prevention technologies to address women's reproductive health needs. This study describes an innovative barrier contraceptive device--based on the SILCS diaphragm--that also provides long-term controlled release of the lead candidate anti-HIV microbicide dapivirine. Diaphragm devices comprising various dapivirine-loaded polymer spring cores overmolded with a nonmedicated silicone elastomer sheath were fabricated by injection molding processes. In vitro release testing, thermal analysis and mechanical characterization were performed on the devices. A diaphragm device containing a polyoxymethylene spring core loaded with 10% w/w dapivirine provided continuous and controlled release of dapivirine over a 6-month period, with a mean in vitro daily release rate of 174 mcg/day. The mechanical properties of the new diaphragm were closely matched to the SILCS diaphragm. The study demonstrates proof of concept for a dapivirine-releasing diaphragm with daily release quantities potentially capable of preventing HIV transmission. In discontinuous clinical use, release of dapivirine may be readily extended over 1 or more years. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Controlled release of metronidazole from composite poly-ε-caprolactone/alginate (PCL/alginate) rings for dental implants.

    Science.gov (United States)

    Lan, Shih-Feng; Kehinde, Timilehin; Zhang, Xiangming; Khajotia, Sharukh; Schmidtke, David W; Starly, Binil

    2013-06-01

    Dental implants provide support for dental crowns and bridges by serving as abutments for the replacement of missing teeth. To prevent bacterial accumulation and growth at the site of implantation, solutions such as systemic antibiotics and localized delivery of bactericidal agents are often employed. The objective of this study was to demonstrate a novel method of controlled localized delivery of antibacterial agents to an implant site using a biodegradable custom fabricated ring. The study involved incorporating a model antibacterial agent (metronidazole) into custom designed poly-ε-caprolactone/alginate (PCL/alginate) composite rings to produce the intended controlled release profile. The rings can be designed to fit around the body of any root form dental implants of various diameters, shapes and sizes. In vitro release studies indicate that pure (100%) alginate rings exhibited an expected burst release of metronidazole in the first few hours, whereas Alginate/PCL composite rings produced a medium burst release followed by a sustained release for a period greater than 4 weeks. By varying the PCL/alginate weight ratios, we have shown that we can control the amount of antibacterial agents released to provide the minimal inhibitory concentration (MIC) needed for adequate protection. The fabricated composite rings have achieved a 50% antibacterial agent release profile over the first 48 h and the remaining amount slowly released over the remainder of the study period. The PCL/alginate agent release characteristic fits the Ritger-Peppas model indicating a diffusion-based mechanism during the 30-day study period. The developed system demonstrates a controllable drug release profile and the potential for the ring to inhibit bacterial biofilm growth for the prevention of diseases such as peri-implantitis resulting from bacterial infection at the implant site. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  4. Bio-kinetic energy harvesting using electroactive polymers

    Science.gov (United States)

    Slade, Jeremiah R.; Bowman, Jeremy; Kornbluh, Roy

    2012-06-01

    In hybrid vehicles, electric motors are used on each wheel to not only propel the car but also to decelerate the car by acting as generators. In the case of the human body, muscles spend about half of their time acting as a brake, absorbing energy, or doing what is known as negative work. Using dielectric elastomers it is possible to use the "braking" phases of walking to generate power without restricting or fatiguing the Warfighter. Infoscitex and SRI have developed and demonstrated methods for using electroactive polymers (EAPs) to tap into the negative work generated at the knee during the deceleration phase of the human gait cycle and convert it into electrical power that can be used to support wearable information systems, including display and communication technologies. The specific class of EAP that has been selected for these applications is termed dielectric elastomers. Because dielectric elastomers dissipate very little mechanical energy into heat, greater amounts of energy can be converted into electricity than by any other method. The long term vision of this concept is to have EAP energy harvesting cells located in components of the Warfighter ensemble, such as the boot uppers, knee pads and eventually even the clothing itself. By properly locating EAPs at these sites it will be possible to not only harvest power from the negative work phase but to actually reduce the amount of work done by the Warfighter's muscles during this phase, thereby reducing fatigue and minimizing the forces transmitted to the joints.

  5. Multimodal nanoporous silica nanoparticles functionalized with aminopropyl groups for improving loading and controlled release of doxorubicin hydrochloride.

    Science.gov (United States)

    Wang, Xin; Li, Chang; Fan, Na; Li, Jing; He, Zhonggui; Sun, Jin

    2017-09-01

    The purpose of this study was to develop amino modified multimodal nanoporous silica nanoparticles (M-NSNs-NH 2 ) loaded with doxorubicin hydrochloride (DOX), intended to enhance the drug loading capacity and to achieve controlled release effect. M-NSNs were functionalized with aminopropyl groups through post-synthesis. The contribution of large pore sizes and surface chemical groups on DOX loading and release were systemically studied using transmission electron microscope (TEM), nitrogen adsorption/desorption measurement, Fourier transform infrared spectroscopy (FTIR), zeta potential analysis, X-ray photoelectron spectroscopy (XPS) and ultraviolet spectrophotometer (UV). The results demonstrated that the NSNs were functionalized with aminopropyl successfully and the DOX molecules were adsorbed inside the nanopores by the hydrogen bonding. The release performance indicated that DOX loaded M-NSNs significantly controlled DOX release, furthermore DOX loaded M-NSNs-NH 2 performed slower controlled release, which was mainly attributed to its stronger hydrogen bonding forces. As expected, we developed a novel carrier with high drug loading capacity and controlled release for DOX. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Flexible control of cellular encapsulation, permeability, and release in a droplet-templated bifunctional copolymer scaffold.

    Science.gov (United States)

    Chen, Qiushui; Chen, Dong; Wu, Jing; Lin, Jin-Ming

    2016-11-01

    Designing cell-compatible, bio-degradable, and stimuli-responsive hydrogels is very important for biomedical applications in cellular delivery and micro-scale tissue engineering. Here, we report achieving flexible control of cellular microencapsulation, permeability, and release by rationally designing a diblock copolymer, alginate-conjugated poly(N-isopropylacrylamide) (Alg-co-PNiPAM). We use the microfluidic technique to fabricate the bifunctional copolymers into thousands of mono-disperse droplet-templated hydrogel microparticles for controlled encapsulation and triggered release of mammalian cells. In particular, the grafting PNiPAM groups in the synthetic cell-laden microgels produce lots of nano-aggregates into hydrogel networks at elevated temperature, thereafter enhancing the permeability of microparticle scaffolds. Importantly, the hydrogel scaffolds are readily fabricated via on-chip quick gelation by triggered release of Ca 2+ from the Ca-EDTA complex; it is also quite exciting that very mild release of microencapsulated cells is achieved via controlled degradation of hydrogel scaffolds through a simple strategy of competitive affinity of Ca 2+ from the Ca-Alginate complex. This finding suggests that we are able to control cellular encapsulation and release through ion-induced gelation and degradation of the hydrogel scaffolds. Subsequently, we demonstrate a high viability of microencapsulated cells in the microgel scaffolds.

  7. Agricultural production - Phase 2. Indonesia. Controlled release pesticide formulations

    International Nuclear Information System (INIS)

    Vollner, L.

    1992-01-01

    At the request of the Government of Indonesia, an IAEA expert undertook a two weeks mission from 2 to 15 April 1991, and continued it from the 9 to 22 November 1991 at the Center for Application of Isotopes and Radiation (CAIR) of the National Atomic Energy Agency, BATAN in Jakarta. Expert discussed the project and carried out experiments together with the staff of the center, introducing shellac (description in part II) as a candidate for controlled release formulations. Formulations of carbofuran, butachlor, 2,4-D and diazinon were carried out, using sand and cocconut shells as carriers. Release rates of a.i. into water have been checked and further work has been discussed. Expert assessed further needs for supply of instruments, accessories and chemicals. (author)

  8. Absorption of controlled-release iron

    International Nuclear Information System (INIS)

    Cook, J.D.; Lipschitz, D.A.; Skikne, B.S.

    1982-01-01

    A multiple-dose double radioiron technic was used to compare absorption of iron administered as a controlled release (CR) capsule and as an elixir; both formulations contained 50 mg elemental iron as ferrous sulfate. When taken by normal subjects in the fasting state, mean absorption from the elixir and CR capsule averaged 4.92% and 4.38%, which gave a CR capsule:elixir ratio of 0.89. This difference was not significant, but when taken with meals that inhibit absorption of dietary iron by different degrees, absorption of the CR formulation was superior. CR capsule:elixir absorption ratios averaged 1.70 from a meal that is mildly inhibitory and 3.13 from a meal that causes more marked inhibition. It is concluded that CR iron formulations may offer a therapeutic advantage to patients who take oral iron with meals to avoid gastrointestinal side effects

  9. New cellulose–lignin hydrogels and their application in controlled release of polyphenols

    International Nuclear Information System (INIS)

    Ciolacu, Diana; Oprea, Ana Maria; Anghel, Narcis; Cazacu, Georgeta; Cazacu, Maria

    2012-01-01

    Novel superabsorbant cellulose–lignin hydrogels (CL) were prepared by a new two-step procedure consisting in dissolving cellulose in an alkaline solution with further mixing with lignin, followed by the chemical crosslinking with epichlorohydrin. The crosslinking occurrence was verified by Fourier Transform Infrared spectroscopy (FT-IR). The effect of the structure features of cellulose–lignin hydrogels on their dehydration heat was evaluated by Differential Scanning Calorimetry (DSC). The Scanning Electron Microscopy (SEM) images reveal some morphological aspects of the hydrogels. The degree as well as the rate of swelling in a mixture of water:ethanol = 19:1 were estimated. The possible application of these hydrogels as controlled release systems was tested. Polyphenols known as having a wide range of biological effects were selected to be incorporated in such hydrogels by an optimal procedure. The extract of grapes seeds from the Chambourcin type was used as a source of polyphenols (PF). The amount of the incorporated polyphenols was estimated by UV–VIS measurements. Characterization of the hydrogels containing polyphenols was performed by FTIR spectroscopy. Some parameters were estimated based on the registered spectra, as H-bond energy (E H ), the asymmetric index (a/b) and the enthalpy of H-bond formation (ΔH). The modifications of the thermal behavior and morphology induced by the presence of the polyphenols in hydrogels were highlighted by DSC and SEM, respectively. The release of polyphenols from CL hydrogels depended on the lignin content from matrices, as assessed by spectral studies. Both loading with polyphenols and their release can be controlled by the composition of the hydrogels. The kinetic of polyphenols release was studied. - Highlights: ► A unique method to obtain cellulose–lignin hydrogels. ► The application of these hydrogels as controlled release systems was tested. ► Polyphenols from grapes seed as active ingredient.

  10. Static and Dynamic Studies of Electro-Active Polymer Actuators and Integration in a Demonstrator

    Directory of Open Access Journals (Sweden)

    Pauline Poncet

    2017-05-01

    Full Text Available Nowadays, the haptic effect is used and developed for many applications—particularly in the automotive industry, where the mechanical feedback induced by a haptic system enables the user to receive information while their attention is kept on the road and on driving. This article presents the development of a vibrotactile button based on printed piezoelectric polymer actuation. Firstly, the characterization of the electro-active polymer used as the actuator and the development of a model able to predict the electromechanical behavior of this device are summarized. Then, the design of circular membranes and their dynamic characterization are presented. Finally, this work is concluded with the construction of a fully functional demonstrator, integrating haptic buttons leading to a clear haptic sensation for the user.

  11. Natural Non-Mulberry Silk Nanoparticles for Potential-Controlled Drug Release

    Science.gov (United States)

    Wang, Juan; Yin, Zhuping; Xue, Xiang; Kundu, Subhas C.; Mo, Xiumei; Lu, Shenzhou

    2016-01-01

    Natural silk protein nanoparticles are a promising biomaterial for drug delivery due to their pleiotropic properties, including biocompatibility, high bioavailability, and biodegradability. Chinese oak tasar Antheraea pernyi silk fibroin (ApF) nanoparticles are easily obtained using cations as reagents under mild conditions. The mild conditions are potentially advantageous for the encapsulation of sensitive drugs and therapeutic molecules. In the present study, silk fibroin protein nanoparticles are loaded with differently-charged small-molecule drugs, such as doxorubicin hydrochloride, ibuprofen, and ibuprofen-Na, by simple absorption based on electrostatic interactions. The structure, morphology and biocompatibility of the silk nanoparticles in vitro are investigated. In vitro release of the drugs from the nanoparticles depends on charge-charge interactions between the drugs and the nanoparticles. The release behavior of the compounds from the nanoparticles demonstrates that positively-charged molecules are released in a more prolonged or sustained manner. Cell viability studies with L929 demonstrated that the ApF nanoparticles significantly promoted cell growth. The results suggest that Chinese oak tasar Antheraea pernyi silk fibroin nanoparticles can be used as an alternative matrix for drug carrying and controlled release in diverse biomedical applications. PMID:27916946

  12. Controlling Object Heat Release Rate using Geometrical Features

    OpenAIRE

    Kraft, Stefan Marc

    2017-01-01

    An experimental study was conducted to determine the effect of complex geometries on the burning rate of materials made using additive manufacturing. Controlling heat release rate has applicability in limiting fire hazards as well as for designing fuels for optimal burning rate. The burning rate of a structure is a function of the material properties as well as the airflow through it, which is dictated by the geometry. This burning rate is generally proportional to the porosity for obj...

  13. Advances in research of targeting delivery and controlled release of drug-loaded nanoparticles

    International Nuclear Information System (INIS)

    Tan Zhonghua

    2003-01-01

    Biochemistry drug, at present, is still the main tool that human struggle to defeat the diseases. So, developing safe and efficacious technique of drug targeting delivery and controlled release is key to enhance curative effect, decrease drug dosage, and lessen its side effect. Drug-loaded nanoparticles, which is formed by conjugate between nanotechnology and modern pharmaceutics, is a new fashioned pharmic delivery carrier. Because of advantages in pharmic targeting transport and controlled or slow release and improving bioavailability, it has been one of developing trend of modern pharmaceutical dosage forms

  14. Order release strategies to control outsourced operations in a supply chain

    NARCIS (Netherlands)

    Boulaksil, Y.; Fransoo, J.C.

    2007-01-01

    In this paper, we propose and compare three different order release strategies to plan and control outsourced operations in a supply chian where the contract manfacturer is producing different variants of a certain product.

  15. Development of novel diclofenac potassium controlled release tablets by wet granulation technique and the effect of co-excipients on in vitro drug release rates.

    Science.gov (United States)

    Shah, Shefaatullah; Khan, Gul Majid; Jan, Syed Umer; Shah, Kifayatullah; Hussain, Abid; Khan, Haroon; Khan, Haroon; Khan, Haroon; Khan, Kamran Ahmad

    2012-01-01

    The aim of the present study was the formulation and evaluation of controlled release polymeric tablets of Diclofenac Potassium by wet granulation method for the release rate, release pattern and the mechanism involved in drug release. Formulations having three grades of polymer Ethocel (7P; 7FP, 10P, 10FP, 100P, 100FP) in several drugs to polymer ratios (10:3 and 10:1) were compressed into tablets using wet granulation method. Co-excipients were added to some selected formulations to investigate their enhancement effect on in vitro drug release patterns. In vitro drug release studies were performed using USP Method-1 (Rotating Basket method) and Phosphate buffer (pH 7.4) was used as a dissolution medium. The similarities and dissimilarities of release profiles of test formulations with reference standard were checked using f2 similarity factor and f1 dissimilarity factor. Mathematical/Kinetic models were employed to determine the release mechanism and drug release kinetics.

  16. Ethyl cellulose microcapsules for protecting and controlled release of folic acid.

    Science.gov (United States)

    Prasertmanakit, Satit; Praphairaksit, Nalena; Chiangthong, Worawadee; Muangsin, Nongnuj

    2009-01-01

    Ethyl cellulose microcapsules were developed for use as a drug-delivery device for protecting folic acid from release and degradation in the undesirable environmental conditions of the stomach, whilst allowing its release in the intestinal tract to make it available for absorption. The controlled release folic acid-loaded ethyl cellulose microcapsules were prepared by oil-in-oil emulsion solvent evaporation using a mixed solvent system, consisting of a 9:1 (v/v) ratio of acetone:methanol and light liquid paraffin as the dispersed and continuous phase. Span 80 was used as the surfactant to stabilize the emulsion. Scanning electron microscopy revealed that the microcapsules had a spherical shape. However, the particulate properties and in vitro release profile depended on the concentrations of the ethyl cellulose, Span 80 emulsifier, sucrose (pore inducer), and folic acid. The average diameter of the microcapsules increased from 300 to 448 microm, whilst the folic acid release rate decreased from 52% to 40%, as the ethyl cellulose concentration was increased from 2.5% to 7.5% (w/v). Increasing the Span 80 concentration from 1% to 4% (v/v) decreased the average diameter of microcapsules from 300 to 141 microm and increased the folic acid release rate from 52% to 79%. The addition of 2.5-7.5% (w/v) of sucrose improved the folic acid release from the microcapsules. The entrapment efficiency was improved from 64% to 88% when the initial folic acid concentration was increased from 1 to 3 mg/ml.

  17. Microgels produced using microfluidic on-chip polymer blending for controlled released of VEGF encoding lentivectors.

    Science.gov (United States)

    Madrigal, Justin L; Sharma, Shonit N; Campbell, Kevin T; Stilhano, Roberta S; Gijsbers, Rik; Silva, Eduardo A

    2018-03-15

    Alginate hydrogels are widely used as delivery vehicles due to their ability to encapsulate and release a wide range of cargos in a gentle and biocompatible manner. The release of encapsulated therapeutic cargos can be promoted or stunted by adjusting the hydrogel physiochemical properties. However, the release from such systems is often skewed towards burst-release or lengthy retention. To address this, we hypothesized that the overall magnitude of burst release could be adjusted by combining microgels with distinct properties and release behavior. Microgel suspensions were generated using a process we have termed on-chip polymer blending to yield composite suspensions of a range of microgel formulations. In this manner, we studied how alginate percentage and degradation relate to the release of lentivectors. Whereas changes in alginate percentage had a minimal impact on lentivector release, microgel degradation led to a 3-fold increase, and near complete release, over 10 days. Furthermore, by controlling the amount of degradable alginate present within microgels the relative rate of release can be adjusted. A degradable formulation of microgels was used to deliver vascular endothelial growth factor (VEGF)-encoding lentivectors in the chick chorioallantoic membrane (CAM) assay and yielded a proangiogenic response in comparison to the same lentivectors delivered in suspension. The utility of blended microgel suspensions may provide an especially appealing platform for the delivery of lentivectors or similarly sized therapeutics. Genetic therapeutics hold considerable potential for the treatment of diseases and disorders including ischemic cardiovascular diseases. To realize this potential, genetic vectors must be precisely and efficiently delivered to targeted regions of the body. However, conventional methods of delivery do not provide sufficient spatial and temporal control. Here, we demonstrate how alginate microgels provide a basis for developing systems for

  18. Controlled release of cortisone drugs from block copolymers synthetized by ATRP

    Science.gov (United States)

    Valenti, G.; La Carta, S.; Mazzotti, G.; Rapisarda, M.; Perna, S.; Di Gesù, R.; Giorgini, L.; Carbone, D.; Recca, G.; Rizzarelli, P.

    2016-05-01

    Diseases affecting posterior eye segment, like macular edema, infection and neovascularization, may cause visual impairment. Traditional treatments, such as steroidal-drugs intravitreal injections, involve chronic course of therapy usually over a period of years. Moreover, they can require frequent administrations of drug in order to have an adequately disease control. This dramatically reduce patient's compliance. Efforts have been made to develop implantable devices that offer an alternative therapeutic approach to bypass many challenges of conventional type of therapy. Implantable drug delivery systems (DDS) have been developed to optimize therapeutic properties of drugs and ensure their slow release in the specific site. Polymeric materials can play an essential role in modulating drug delivery and their use in such field has become indispensable. During last decades, acrylic polymers have obtained growing interest. Biocompatibility and chemical properties make them extremely versatile, allowing their use in many field such as biomedical. In particular, block methacrylate copolymer with a balance of hydrophilic and hydrophobic properties can be suitable for prolonged DDS in biomedical devices. In this work, we focused on the realization of a system for controlled and long term release of betamethasone 17,21-dipropionate (BDP), a cortisone drug, from methacrylic block copolymers, to be tested in the treatment of the posterior eye's diseases. Different series of methyl methacrylate/hydroxyethyl methacrylate (MMA/HEMA) block and random copolymers, with different monomer compositions (10-60% HEMA), were synthetized by Atom Transfer Radical Polymerization (ATRP) to find the best hydrophilic/hydrophobic ratio, able to ensure optimal kinetic release. Copolymer samples were characterized by NMR spectroscopy (1H-NMR, 13C-NMR, CosY), SEC, TGA and DSC. Monitoring of drug release from films loaded with BDP was carried out by HPLC analysis. Evaluation of different kinetic

  19. Controlled release of cortisone drugs from block copolymers synthetized by ATRP

    Energy Technology Data Exchange (ETDEWEB)

    Valenti, G.; La Carta, S.; Rapisarda, M.; Carbone, D.; Recca, G.; Rizzarelli, P., E-mail: paola.rizzarelli@cnr.it [Istituto per i Polimeri, Compositi e Biomateriali, Consiglio Nazionale delle Ricerche Via P. Gaifami 18, 95129 Catania (Italy); Mazzotti, G.; Giorgini, L. [Dipartimento di Chimica Industriale «Toso Montanari», Università di Bologna Via Risorgimento 4, 40136 Bologna (Italy); Perna, S. [ST Microelectronics Srl, Stradale Primosole, 50–95121 Catania (Italy); Di Gesù, R. [Merck Serono S.p.A., Via L. Einaudi, 11–00012 Guidonia Montecelio, Rome (Italy)

    2016-05-18

    Diseases affecting posterior eye segment, like macular edema, infection and neovascularization, may cause visual impairment. Traditional treatments, such as steroidal-drugs intravitreal injections, involve chronic course of therapy usually over a period of years. Moreover, they can require frequent administrations of drug in order to have an adequately disease control. This dramatically reduce patient’s compliance. Efforts have been made to develop implantable devices that offer an alternative therapeutic approach to bypass many challenges of conventional type of therapy. Implantable drug delivery systems (DDS) have been developed to optimize therapeutic properties of drugs and ensure their slow release in the specific site. Polymeric materials can play an essential role in modulating drug delivery and their use in such field has become indispensable. During last decades, acrylic polymers have obtained growing interest. Biocompatibility and chemical properties make them extremely versatile, allowing their use in many field such as biomedical. In particular, block methacrylate copolymer with a balance of hydrophilic and hydrophobic properties can be suitable for prolonged DDS in biomedical devices. In this work, we focused on the realization of a system for controlled and long term release of betamethasone 17,21-dipropionate (BDP), a cortisone drug, from methacrylic block copolymers, to be tested in the treatment of the posterior eye’s diseases. Different series of methyl methacrylate/hydroxyethyl methacrylate (MMA/HEMA) block and random copolymers, with different monomer compositions (10–60% HEMA), were synthetized by Atom Transfer Radical Polymerization (ATRP) to find the best hydrophilic/hydrophobic ratio, able to ensure optimal kinetic release. Copolymer samples were characterized by NMR spectroscopy ({sup 1}H-NMR, {sup 13}C-NMR, CosY), SEC, TGA and DSC. Monitoring of drug release from films loaded with BDP was carried out by HPLC analysis. Evaluation of

  20. Controlled release of cortisone drugs from block copolymers synthetized by ATRP

    International Nuclear Information System (INIS)

    Valenti, G.; La Carta, S.; Rapisarda, M.; Carbone, D.; Recca, G.; Rizzarelli, P.; Mazzotti, G.; Giorgini, L.; Perna, S.; Di Gesù, R.

    2016-01-01

    Diseases affecting posterior eye segment, like macular edema, infection and neovascularization, may cause visual impairment. Traditional treatments, such as steroidal-drugs intravitreal injections, involve chronic course of therapy usually over a period of years. Moreover, they can require frequent administrations of drug in order to have an adequately disease control. This dramatically reduce patient’s compliance. Efforts have been made to develop implantable devices that offer an alternative therapeutic approach to bypass many challenges of conventional type of therapy. Implantable drug delivery systems (DDS) have been developed to optimize therapeutic properties of drugs and ensure their slow release in the specific site. Polymeric materials can play an essential role in modulating drug delivery and their use in such field has become indispensable. During last decades, acrylic polymers have obtained growing interest. Biocompatibility and chemical properties make them extremely versatile, allowing their use in many field such as biomedical. In particular, block methacrylate copolymer with a balance of hydrophilic and hydrophobic properties can be suitable for prolonged DDS in biomedical devices. In this work, we focused on the realization of a system for controlled and long term release of betamethasone 17,21-dipropionate (BDP), a cortisone drug, from methacrylic block copolymers, to be tested in the treatment of the posterior eye’s diseases. Different series of methyl methacrylate/hydroxyethyl methacrylate (MMA/HEMA) block and random copolymers, with different monomer compositions (10–60% HEMA), were synthetized by Atom Transfer Radical Polymerization (ATRP) to find the best hydrophilic/hydrophobic ratio, able to ensure optimal kinetic release. Copolymer samples were characterized by NMR spectroscopy ("1H-NMR, "1"3C-NMR, CosY), SEC, TGA and DSC. Monitoring of drug release from films loaded with BDP was carried out by HPLC analysis. Evaluation of different

  1. Incorporation of fused tetrathiafulvalenes (TTFs) into polythiophene architectures: varying the electroactive dominance of the TTF species in hybrid systems.

    Science.gov (United States)

    Berridge, Rory; Skabara, Peter J; Pozo-Gonzalo, Cristina; Kanibolotsky, Alexander; Lohr, Jan; McDouall, Joseph J W; McInnes, Eric J L; Wolowska, Joanna; Winder, Christoph; Sariciftci, N Serdar; Harrington, Ross W; Clegg, William

    2006-02-23

    A novel polythienylenevinylene (PTV) and two new polythiophenes (PTs), featuring fused tetrathiafulvalene (TTF) units, have been prepared and characterized by ultraviolet-visible (UV-vis) and electron paramagnetic resonance (EPR) spectroelectrochemistry. All polymers undergo two sequential, reversible oxidation processes in solution. Structures in which the TTF species is directly linked to the polymer backbone (2 and 4) display redox behavior which is dictated by the fulvalene system. Once the TTF is spatially removed from the polymer chain by a nonconjugated link (polymer 3), the electroactivity of both TTF and polythiophene moieties can be detected. Computational studies confirm the delocalization of charge over both electroactive centers (TTF and PT) and the existence of a triplet dication intermediate. PTV 4 has a low band gap (1.44 eV), is soluble in common organic solvents, and is stable under ambient conditions. Organic solar cells of polymer 4:[6,6]-phenyl-C(61) butyric acid methyl ester (PCBM) have been fabricated. Under illumination, a photovoltaic effect is observed with a power conversion efficiency of 0.13% under AM1.5 solar simulated light. The onset of photocurrent at 850 nm is consistent with the onset of the pi-pi absorption band of the polymer. Remarkably, UV-vis spectroelectrochemistry of polymer 4 reveals that the conjugated polymer chain remains unchanged during the oxidation of the polymer.

  2. Construction of a controlled-release delivery system for pesticides using biodegradable PLA-based microcapsules.

    Science.gov (United States)

    Liu, Baoxia; Wang, Yan; Yang, Fei; Wang, Xing; Shen, Hong; Cui, Haixin; Wu, Decheng

    2016-08-01

    Conventional pesticides usually need to be used in more than recommended dosages due to their loss and degradation, which results in a large waste of resources and serious environmental pollution. Encapsulation of pesticides in biodegradable carriers is a feasible approach to develop environment-friendly and efficient controlled-release delivery system. In this work, we fabricated three kinds of polylactic acid (PLA) carriers including microspheres, microcapsules, and porous microcapsules for controlled delivery of Lambda-Cyhalothrin (LC) via premix membrane emulsification (PME). The microcapsule delivery system had better water dispersion than the other two systems. Various microcapsules with a high LC contents as much as 40% and tunable sizes from 0.68 to 4.6μm were constructed by manipulating the process parameters. Compared with LC technical and commercial microcapsule formulation, the microcapsule systems showed a significantly sustained release of LC for a longer period. The LC release triggered by LC diffusion and matrix degradation could be optimally regulated by tuning LC contents and particle sizes of the microcapsules. This multi-regulated release capability is of great significance to achieve the precisely controlled release of pesticides. A preliminary bioassay against plutella xylostella revealed that 0.68μm LC-loaded microcapsules with good UV and thermal stability exhibited an activity similar to a commercial microcapsule formulation. These results demonstrated such an aqueous microcapsule delivery system had a great potential to be further explored for developing an effective and environmentally friendly pesticide-release formulation. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. EDITORIAL: Electroactive polymer materials

    Science.gov (United States)

    Bar-Cohen, Yoseph; Kim, Kwang J.; Ryeol Choi, Hyouk; Madden, John D. W.

    2007-04-01

    Imitating nature's mechanisms offers enormous potential for the improvement of our lives and the tools we use. This field of the study and imitation of, and inspiration from, nature's methods, designs and processes is known as biomimetics. Artificial muscles, i.e. electroactive polymers (EAPs), are one of the emerging technologies enabling biomimetics. Polymers that can be stimulated to change shape or size have been known for many years. The activation mechanisms of such polymers include electrical, chemical, pneumatic, optical and magnetic. Electrical excitation is one of the most attractive stimulators able to produce elastic deformation in polymers. The convenience and practicality of electrical stimulation and the continual improvement in capabilities make EAP materials some of the most attractive among activatable polymers (Bar-Cohen Y (ed) 2004 Electroactive Polymer (EAP) Actuators as Artificial Muscles—Reality, Potential and Challenges 2nd edn, vol PM136 (Bellingham, WA: SPIE Press) pp 1-765). As polymers, EAP materials offer many appealing characteristics that include low weight, fracture tolerance and pliability. Furthermore, they can be configured into almost any conceivable shape and their properties can be tailored to suit a broad range of requirements. These capabilities and the significant change of shape or size under electrical stimulation while being able to endure many cycles of actuation are inspiring many potential possibilities for EAP materials among engineers and scientists in many different disciplines. Practitioners in biomimetics are particularly excited about these materials since they can be used to mimic the movements of animals and insects. Potentially, mechanisms actuated by EAPs will enable engineers to create devices previously imaginable only in science fiction. For many years EAP materials received relatively little attention due to their poor actuation capability and the small number of available materials. In the last fifteen

  4. IONP-doped nanoparticles for highly effective NIR-controlled drug release and combination tumor therapy

    Directory of Open Access Journals (Sweden)

    Fu X

    2017-05-01

    Full Text Available Xudong Fu,1 Xinjun Wang,1 Shaolong Zhou,1 Yanyan Zhang2 1The Fifth Affiliated Hospital of Zhengzhou University, 2School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, People’s Republic of China Abstract: Despite advances in controlled drug delivery, drug delivery systems (DDSs with controlled activated drug release and high spatial and temporal resolution are still required. Theranostic nanomedicine is capable of diagnosis, therapy, and monitoring the delivery and distribution of drug molecules and has received growing interest. In this study, a near-infrared light-controlled “off–on” DDS with magnetic resonance imaging and magnetic targeting properties was developed using a hybrid nanoplatform (carbon nanotubes [CNTs]-iron oxide nanoparticle. Doxorubicin (DOX and distearoyl-sn-glycero-3-phosphoethanolamine-PEG were adsorbed onto CNTs-iron oxide nanoparticle, and then to avoid the unexpected drug release during circulation, 1-myristyl alcohol was used to encapsulate the CNTs–drug complex. Herein, multifunctional DOX-loaded nanoparticles (NPs with “off–on” state were developed. DOX-NPs showed an obvious “off–on” effect (temperature increase, drug release controlled by near-infrared light in vitro and in vivo. In the in vivo and in vitro studies, DOX-NPs exhibited excellent magnetic resonance imaging ability, magnetic targeting property, high biosafety, and high antitumor combined therapeutic efficacy (hyperthermia combined with chemotherapy. These results highlight the great potential of DOX-NPs in the treatment of cancer. Keywords: controlled drug release, magnetic targeting, MRI, combination therapy

  5. Hydrophilic magnetic nanoclusters with thermo-responsive properties and their drug controlled release

    International Nuclear Information System (INIS)

    Meerod, Siraprapa; Rutnakornpituk, Boonjira; Wichai, Uthai; Rutnakornpituk, Metha

    2015-01-01

    Synthesis and drug controlled release properties of thermo-responsive magnetic nanoclusters grafted with poly(N-isopropylacrylamide) (poly(NIPAAm)) and poly(NIPAAm-co-poly(ethylene glycol) methyl ether methacrylate) (PEGMA) copolymers were described. These magnetic nanoclusters were synthesized via an in situ radical polymerization in the presence of acrylamide-grafted magnetic nanoparticles (MNPs). Poly(NIPAAm) provided thermo-responsive properties, while PEGMA played a role in good water dispersibility to the nanoclusters. The ratios of PEGMA to NIPAAm in the (co)polymerization in the presence of the MNPs were fine-tuned such that the nanoclusters with good water dispersibility, good magnetic sensitivity and thermo responsiveness were obtained. The size of the nanoclusters was in the range of 50–100 nm in diameter with about 100–200 particles/cluster. The nanoclusters were well dispersible in water at room temperature and can be suddenly agglomerated when temperature was increased beyond the lower critical solution temperature (LCST) (32 °C). The release behavior of an indomethacin model drug from the nanoclusters was also investigated. These novel magnetic nanoclusters with good dispersibility in water and reversible thermo-responsive properties might be good candidates for the targeting drug controlled release applications. - Highlights: • Nanoclusters with good water dispersibility and magnetic response were prepared. • They were grafted with thermo-responsive poly(NIPAAm) and/or poly(PEGMA). • Poly(NIPAAm) provided thermo-responsive properties to the nanoclusters. • Poly(PEGMA) provided good water dispersibilityto the nanoclusters. • Accelerated and controllable releases of a drug from the nanoclusters were shown

  6. Nanostructural control of methane release in kerogen and its implications to wellbore production decline

    Science.gov (United States)

    Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

    2016-06-01

    Despite massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix-a limiting step in shale gas extraction. Using molecular simulations, we here show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30-47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3-35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release.

  7. The performance of workload control concepts in job shops : Improving the release method

    NARCIS (Netherlands)

    Land, MJ; Gaalman, GJC

    1998-01-01

    A specific class of production control concepts for jobs shops is based on the principles of workload control. Practitioners emphasise the importance of workload control. However, order release methods that reduce the workload on the shop floor show poor due date performance in job shop simulations.

  8. Nanocoating of ionic liquid and polypyrrole for durable electro-active paper actuators working under ambient conditions

    International Nuclear Information System (INIS)

    Mahadeva, Suresha K; Kim, Jaehwan

    2010-01-01

    This paper reports that nanocoating of polypyrrole (PPy) and ionic liquid (IL) on cellulose film improves the electromechanical performance and durability of a cellulose electro-active paper actuator. Cellulose-PPy-IL nanocomposites were fabricated by the polymerization-induced adsorption process of PPy followed by subsequent activation in IL solutions. X-ray photoelectron spectroscopy, transmission electron microscopy and secondary ion mass spectroscopy analyses validated the successful nanocoating of the PPy and IL layers on the cellulose. The results revealed that the cellulose-PPy-IL nanocomposites are suitable for durable bending actuators working under ambient conditions. Preparation, characterization and performance test of the nanocomposites are explained.

  9. Nanocapsule@xerogel microparticles containing sodium diclofenac: a new strategy to control the release of drugs.

    Science.gov (United States)

    da Fonseca, Letícia Sias; Silveira, Rodrigo Paulo; Deboni, Alberto Marçal; Benvenutti, Edilson Valmir; Costa, Tânia M H; Guterres, Sílvia S; Pohlmann, Adriana R

    2008-06-24

    The aim of this work was to evaluate the potentiality to control the drug release of a new architecture of microparticles organized at the nanoscopic scale by assembling polymeric nanocapsules at the surface of drug-loaded xerogels. Xerogel was prepared by sol-gel method using sodium diclofenac, as hydrophilic drug model, and coated by spray-drying. After coating, the surface areas decreased from 82 to 28 m(2)/g, the encapsulation efficiency was 71% and SEM analysis showed irregular microparticles coated by the nanocapsules. Formulation showed satisfactory gastro-resistance presenting drug release lower than 3% (60 min) in acid medium. In water, the pure drug dissolved 92% after 5 min, uncoated drug-loaded xerogel released 60% and nanocapsule coated drug-loaded xerogel 36%. After 60 min, uncoated drug-loaded xerogel released 82% and nanocapsule coated drug-loaded xerogel 62%. In conclusion, the new system was able to control the release of the hydrophilic drug model.

  10. Floating tablets for controlled release of ofloxacin via compression coating of hydroxypropyl cellulose combined with effervescent agent.

    Science.gov (United States)

    Qi, Xiaole; Chen, Haiyan; Rui, Yao; Yang, Fengjiao; Ma, Ning; Wu, Zhenghong

    2015-07-15

    To prolong the residence time of dosage forms within gastrointestinal trace until all drug released at desired rate was one of the real challenges for oral controlled-release drug delivery system. Herein, we developed a fine floating tablet via compression coating of hydrophilic polymer (hydroxypropyl cellulose) combined with effervescent agent (sodium bicarbonate) to achieve simultaneous control of release rate and location of ofloxacin. Sodium alginate was also added in the coating layer to regulate the drug release rate. The effects of the weight ratio of drug and the viscosity of HPC on the release profile were investigated. The optimized formulations were found to immediately float within 30s and remain lastingly buoyant over a period of 12 h in simulated gastric fluid (SGF, pH 1.2) without pepsin, indicating a satisfactory floating and zero-order drug release profile. In addition, the oral bioavailability experiment in New Zealand rabbits showed that, the relative bioavailability of the ofloxacin after administrated of floating tablets was 172.19%, compared to marketed common release tablets TaiLiBiTuo(®). These results demonstrated that those controlled-released floating tables would be a promising gastro-retentive delivery system for drugs acting in stomach. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Nitrogen mineralization and volatilization from controlled release urea fertilizers in selected malaysian soils

    International Nuclear Information System (INIS)

    Singh, K.J.K.A.; Yusop, M.K.; Oad, F.C.

    2017-01-01

    Controlled release urea fertilizers are usually used for extended duration in supplying nitrogen. The rate of urea hydrolysis could be efficiently minimized through these fertilizers. Various controlled released fertilizers i.e Uber-10 (30%N), Meister-20 (40%N), Meister-27 (40%N), Humate Coated Urea (45%N), Duration Polymer Coated Urea Type-V (43%N), Gold-N-Sulfur Coated Urea (41%N) and common urea (46%N) were applied to inland soil series of Malaysia. The soil series investigated were: Serdang (Typic Paleudult), Munchong (Typic Hapludox), Segamat (Typic Hapludox), Selangor (Typic Tropaquept), Rengam (Typic Kandiudult) and Holyrood (Typic Kandiudult). The maximum release of ammonium (NH/sub 4/-N) was noted in Gold-N-Sulfur Coated Urea, Humate Coated Urea and common Urea over 8 weeks of incubation. However, the release of NH4-N under the influence of Duration Type-V and Uber-10 took 2nd place. The Meister-20 and Meister-27 had minimum release of NH4-N. Munchong series was efficient in releasing higher NH4-N compared to rest of soils during 8th week of incubation due to higher soil total carbon, low /sub 4/-N and total nitrogen. Ammonia (NH/sub 3/-N) loss progressively increased with unit increase in incubation week and was higher during 6th week of fertilizer application. The higher loss of NH3-N was found in common Urea. However, Meister-20, Meister-27, Duration Polymer Coated Urea Type-V and Uber-10 had lower loss of NH/sub 3/-N due to slow release property and this character could be beneficial for supplying nutrients to next season crop. (author)

  12. Hybrid nanostructured drug carrier with tunable and controlled drug release

    International Nuclear Information System (INIS)

    Depan, D.; Misra, R.D.K.

    2012-01-01

    We describe here a transformative approach to synthesize a hybrid nanostructured drug carrier that exhibits the characteristics of controlled drug release. The synthesis of the nanohybrid architecture involved two steps. The first step involved direct crystallization of biocompatible copolymer along the long axis of the carbon nanotubes (CNTs), followed by the second step of attachment of drug molecule to the polymer via hydrogen bonding. The extraordinary inorganic–organic hybrid architecture exhibited high drug loading ability and is physically stable even under extreme conditions of acidic media and ultrasonic irradiation. The temperature and pH sensitive characteristics of the hybrid drug carrier and high drug loading ability merit its consideration as a promising carrier and utilization of the fundamental aspects used for synthesis of other promising drug carriers. The higher drug release response during the application of ultrasonic frequency is ascribed to a cavitation-type process in which the acoustic bubbles nucleate and collapse releasing the drug. Furthermore, the study underscores the potential of uniquely combining CNTs and biopolymers for drug delivery. - Graphical abstract: Block-copolymer crystallized on carbon nanotubes (CNTs). Nanohybrid drug carrier synthesized by attaching doxorubicin (DOX) to polymer crystallized CNTs. Crystallized polymer on CNTs provide mechanical stability. Triggered release of DOX. Highlights: ► The novel synthesis of a hybrid nanostructured drug carrier is described. ► The drug carrier exhibits high drug loading ability and is physically stable. ► The high drug release is ascribed to a cavitation-type process.

  13. Reinforced poly(propylene oxide): a very soft and extensible dielectric electroactive polymer

    International Nuclear Information System (INIS)

    Goswami, K; Mazurek, P; Daugaard, A E; Skov, A L; Galantini, F; Gallone, G

    2013-01-01

    Poly(propylene oxide) (PPO), a novel soft elastomeric material, and its composites were investigated as a new dielectric electroactive polymer (EAP). The PPO networks were obtained from thiol-ene chemistry by photochemical crosslinking of α,ω-diallyl PPO with a tetra-functional thiol. The elastomer was reinforced with hexamethylenedisilazane treated fumed silica to improve the mechanical properties of PPO. The mechanical properties of PPO and composites thereof were investigated by shear rheology and stress–strain measurements. It was found that incorporation of silica particles improved the stability of the otherwise mechanically weak pure PPO network. Dielectric spectroscopy revealed high relative dielectric permittivity of PPO at 10 3 Hz of 5.6. The relative permittivity was decreased slightly upon addition of fillers, but remained higher than the commonly used acrylic EAP material VHB4910. The electromechanical actuation performance of both PPO and its composites showed properties as good as VHB4910 and a lower viscous loss. (paper)

  14. Accelerated dissolution testing for controlled release microspheres using the flow-through dissolution apparatus.

    Science.gov (United States)

    Collier, Jarrod W; Thakare, Mohan; Garner, Solomon T; Israel, Bridg'ette; Ahmed, Hisham; Granade, Saundra; Strong, Deborah L; Price, James C; Capomacchia, A C

    2009-01-01

    Theophylline controlled release capsules (THEO-24 CR) were used as a model system to evaluate accelerated dissolution tests for process and quality control and formulation development of controlled release formulations. Dissolution test acceleration was provided by increasing temperature, pH, flow rate, or adding surfactant. Electron microscope studies on the theophylline microspheres subsequent to each experiment showed that at pH values of 6.6 and 7.6 the microspheres remained intact, but at pH 8.6 they showed deterioration. As temperature was increased from 37-57 degrees C, no change in microsphere integrity was noted. Increased flow rate also showed no detrimental effect on integrity. The effect of increased temperature was determined to be the statistically significant variable.

  15. Controlled release of volatiles under mild reaction conditions: from nature to everyday products.

    Science.gov (United States)

    Herrmann, Andreas

    2007-01-01

    Volatile organic compounds serve in nature as semiochemicals for communication between species, and are often used as flavors and fragrances in our everyday life. The quite limited longevity of olfactive perception has led to the development of pro-perfumes or pro-fragrances--ideally nonvolatile and odorless fragrance precursors which release the active volatiles by bond cleavage. Only a limited amount of reaction conditions, such as hydrolysis, temperature changes, as well as the action of light, oxygen, enzymes, or microorganisms, can be used to liberate the many different chemical functionalities. This Review describes the controlled chemical release of fragrances and discusses additional challenges such as precursor stability during product storage as well as some aspects concerning toxicity and biodegradability. As the same systems can be applied in different areas of research, the scope of this Review covers fragrance delivery as well as the controlled release of volatiles in general.

  16. A double-blind placebo-controlled study of controlled release fluvoxamine for the treatment of generalized social anxiety disorder

    NARCIS (Netherlands)

    Westenberg, HGM; Stein, DJ; Yang, HC; Li, D; Barbato, LM

    This was a randomized double-blind placebo-controlled multicenter study to assess the efficacy, safety, and tolerability of fluvoxamine in a controlled release (CR) formulation for treatment of generalized social anxiety disorder (GSAD). A total of 300 subjects with GSAD were randomly assigned to

  17. Controlling the release of active compounds from the inorganic carrier halloysite

    Energy Technology Data Exchange (ETDEWEB)

    Tescione, F.; Buonocore, G. G.; Stanzione, M.; Oliviero, M.; Lavorgna, M. [National Research Council - Institute of Composites and Biomedical Materials, P.le E. Fermi, 1 80055 Portici (Naples) (Italy)

    2014-05-15

    Halloysite (HNTs), a natural material characterized by a nanotube structure, has been used as an inorganic carrier of active compounds in several applications from medicine to anticorrosion coatings. In this present work, vanillin (VAN) used as a antimicrobial model, has been encapsulated within HNTs for exploiting its applicability in the active food packaging sector. The molecule release rate has been controlled by crosslinking at the tube ends the loaded vanillin with copper ions, thus producing a stopper network. The vanillin-loaded HNTs were characterized using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis. The antimicrobial release kinetics from the loaded nanoparticles (VAN/HNTs) in water was investigated using UV-vis spectroscopy. The results show that the vanillin crosslinked with cupper ions is a feasible method to tailor the release rate of antimicrobial model from HTNs nanoparticles.

  18. Controlling the release of active compounds from the inorganic carrier halloysite

    International Nuclear Information System (INIS)

    Tescione, F.; Buonocore, G. G.; Stanzione, M.; Oliviero, M.; Lavorgna, M.

    2014-01-01

    Halloysite (HNTs), a natural material characterized by a nanotube structure, has been used as an inorganic carrier of active compounds in several applications from medicine to anticorrosion coatings. In this present work, vanillin (VAN) used as a antimicrobial model, has been encapsulated within HNTs for exploiting its applicability in the active food packaging sector. The molecule release rate has been controlled by crosslinking at the tube ends the loaded vanillin with copper ions, thus producing a stopper network. The vanillin-loaded HNTs were characterized using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis. The antimicrobial release kinetics from the loaded nanoparticles (VAN/HNTs) in water was investigated using UV-vis spectroscopy. The results show that the vanillin crosslinked with cupper ions is a feasible method to tailor the release rate of antimicrobial model from HTNs nanoparticles

  19. Preparation of hydroxypropyl cyclosophoraose/dextran microspheres for the controlled release of ciprofloxacin

    International Nuclear Information System (INIS)

    Lee, Benel; Jeong, Da Ham; Joo, Sang Woo; Choi, Jae Min; Jung, Seung Ho; Cho, Eun Na; Lee, Jae Yung; Park, Se Yeon

    2016-01-01

    Hydroxypropyl cyclosophoraose/dextran (HPCys/dextran) microspheres were prepared using an emulsion polymerization method for use as drug carriers to achieve the controlled release of a poorly water-soluble antibacterial drug, ciprofloxacin (CFX). Cyclosophoraoses are cyclic (1 → 2)-β-d-glucans isolated from the Rhizobium species. Characteristics of HPCys/dextran microspheres were investigated using Fourier transform infrared analysis, solid-state 13C nuclear magnetic resonance spectroscopy, and field emission scanning electron microscopy. The amount of CFX released from these microspheres at pH 7.4 (intestinal phase pH) was about two times higher than that released at pH 1.2 (gastric phase pH). Furthermore, HPCys/dextran microspheres did not show any toxicity in human embryonic kidney cells. We propose that HPCys/dextran microspheres could be used as an effective pH-dependent release system for poorly water-soluble drugs such as CFX

  20. Preparation of hydroxypropyl cyclosophoraose/dextran microspheres for the controlled release of ciprofloxacin

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Benel; Jeong, Da Ham; Joo, Sang Woo; Choi, Jae Min; Jung, Seung Ho; Cho, Eun Na [Center for Biotechnology Research in UBITA (CBRU), Konkuk University, Seoul (Korea, Republic of); Lee, Jae Yung [Dept. Biological Science, Mokpo National University, Mokpo (Korea, Republic of); Park, Se Yeon [Dept. Applied Chemistry, Dongduk Women' s University, Seoul (Korea, Republic of)

    2016-12-15

    Hydroxypropyl cyclosophoraose/dextran (HPCys/dextran) microspheres were prepared using an emulsion polymerization method for use as drug carriers to achieve the controlled release of a poorly water-soluble antibacterial drug, ciprofloxacin (CFX). Cyclosophoraoses are cyclic (1 → 2)-β-d-glucans isolated from the Rhizobium species. Characteristics of HPCys/dextran microspheres were investigated using Fourier transform infrared analysis, solid-state 13C nuclear magnetic resonance spectroscopy, and field emission scanning electron microscopy. The amount of CFX released from these microspheres at pH 7.4 (intestinal phase pH) was about two times higher than that released at pH 1.2 (gastric phase pH). Furthermore, HPCys/dextran microspheres did not show any toxicity in human embryonic kidney cells. We propose that HPCys/dextran microspheres could be used as an effective pH-dependent release system for poorly water-soluble drugs such as CFX.

  1. Silicone Doped Chitosan-Acrylamide Coencapsulated Urea Fertilizer: An Approach to Controlled Release Fertilizers

    Directory of Open Access Journals (Sweden)

    Sempeho Ibahati Siafu

    2017-01-01

    Full Text Available In the absence of special management practices, urea is known to undergo chemical transformations resulting in severe losses (≈60–70% of total fertilizer applied. In an attempt to design urea controlled release fertilizers in order to counterbalance the 60–70% loss, urea was cross-linked with chitosan and acrylamide under refluxed in situ copolymerization technique; the procedures were repeated with silicone doping prior cross-linking with MBA. The particles were characterized with FTIR/ATR, EDX, XRD, and SEM. The IR bands observed within 3426–409 cm−1 revealed the formation of new bands after coencapsulation for the νγN-H, νβN-H, νOH, νsNH2, νCH2, νC=O, δ′NH2, νC=C, δNH2, νC-N, βCH3, $C-N, γNH2, νC=O, and $CH2. Crystallinity indices for urea with and without silicone doping were found to be 50.9% and 72.1%, respectively, with a distinctive split peak at (d 12.30°. The formation of Microdunes and Microballs 3D network sized 0.64 μm was noted. Release profiles demonstrated that 80% N was released in a period of 30 days at RT and pH 7. The release patterns exhibited linear and deformed sigmoid release models. Empirically, the findings demonstrated that it is possible to design urea controlled release fertilizers with varying particle sizes and morphologies by using chitosan-acrylamide coencapsulation.

  2. Effective control of modified palygorskite to NH4+-N release from sediment.

    Science.gov (United States)

    Chen, Lei; Zheng, Tianyuan; Zhang, Junjie; Liu, Jie; Zheng, Xilai

    2014-01-01

    Sediment capping is an in situ treatment technology that can effectively restrain nutrient and pollutant release from the sediment in lakes and reservoirs. Research on sediment capping has focused on the search for effective, non-polluting and affordable capping materials. The efficiency and mechanism of sediment capping with modified palygorskite in preventing sediment ammonia nitrogen (NH4+-N) release to surface water were investigated through a series of batch and sediment capping experiments. Purified palygorskite and different types of modified palygorskite (i.e. heated, acid-modified and NaCI-modified palygorskite) were used in this investigation. Factors affecting control efficiency, including the temperature, thickness and grain size of the capping layer, were also analysed. The batch tests showed that the adsorption of NH4+-N on modified palygorskite achieved an equilibration in the initial 45 min, and the adsorption isotherm followed the Freundlich equation. Sediment capping experiments showed that compared with non-capped condition, covering the sediment with modified palygorskite and sand both inhibited NH4+-N release to the overlying water. Given its excellent chemical stability and strong adsorption, heated palygorskite, which has a NH4+-N release inhibition ratio of 41.3%, is a more effective sediment capping material compared with sand. The controlling effectiveness of the modified palygorskite increases with thicker capping layer, lower temperature and smaller grain size of the capping material.

  3. Munc13 controls the location and efficiency of dense-core vesicle release in neurons.

    Science.gov (United States)

    van de Bospoort, Rhea; Farina, Margherita; Schmitz, Sabine K; de Jong, Arthur; de Wit, Heidi; Verhage, Matthijs; Toonen, Ruud F

    2012-12-10

    Neuronal dense-core vesicles (DCVs) contain diverse cargo crucial for brain development and function, but the mechanisms that control their release are largely unknown. We quantified activity-dependent DCV release in hippocampal neurons at single vesicle resolution. DCVs fused preferentially at synaptic terminals. DCVs also fused at extrasynaptic sites but only after prolonged stimulation. In munc13-1/2-null mutant neurons, synaptic DCV release was reduced but not abolished, and synaptic preference was lost. The remaining fusion required prolonged stimulation, similar to extrasynaptic fusion in wild-type neurons. Conversely, Munc13-1 overexpression (M13OE) promoted extrasynaptic DCV release, also without prolonged stimulation. Thus, Munc13-1/2 facilitate DCV fusion but, unlike for synaptic vesicles, are not essential for DCV release, and M13OE is sufficient to produce efficient DCV release extrasynaptically.

  4. HPMA Copolymer-Drug Conjugates with Controlled Tumor-Specific Drug Release.

    Science.gov (United States)

    Chytil, Petr; Koziolová, Eva; Etrych, Tomáš; Ulbrich, Karel

    2018-01-01

    Over the past few decades, numerous polymer drug carrier systems are designed and synthesized, and their properties are evaluated. Many of these systems are based on water-soluble polymer carriers of low-molecular-weight drugs and compounds, e.g., cytostatic agents, anti-inflammatory drugs, or multidrug resistance inhibitors, all covalently bound to a carrier by a biodegradable spacer that enables controlled release of the active molecule to achieve the desired pharmacological effect. Among others, the synthetic polymer carriers based on N-(2-hydroxypropyl) methacrylamide (HPMA) copolymers are some of the most promising carriers for this purpose. This review focuses on advances in the development of HPMA copolymer carriers and their conjugates with anticancer drugs, with triggered drug activation in tumor tissue and especially in tumor cells. Specifically, this review highlights the improvements in polymer drug carrier design with respect to the structure of a spacer to influence controlled drug release and activation, and its impact on the drug pharmacokinetics, enhanced tumor uptake, cellular trafficking, and in vivo antitumor activity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Electroactive Tissue Scaffolds with Aligned Pores as Instructive Platforms for Biomimetic Tissue Engineering.

    Science.gov (United States)

    Hardy, John G; Cornelison, R Chase; Sukhavasi, Rushi C; Saballos, Richard J; Vu, Philip; Kaplan, David L; Schmidt, Christine E

    2015-01-14

    Tissues in the body are hierarchically structured composite materials with tissue-specific chemical and topographical properties. Here we report the preparation of tissue scaffolds with macroscopic pores generated via the dissolution of a sacrificial supramolecular polymer-based crystal template (urea) from a biodegradable polymer-based scaffold (polycaprolactone, PCL). Furthermore, we report a method of aligning the supramolecular polymer-based crystals within the PCL, and that the dissolution of the sacrificial urea yields scaffolds with macroscopic pores that are aligned over long, clinically-relevant distances ( i.e ., centimeter scale). The pores act as topographical cues to which rat Schwann cells respond by aligning with the long axis of the pores. Generation of an interpenetrating network of polypyrrole (PPy) and poly(styrene sulfonate) (PSS) in the scaffolds yields electroactive tissue scaffolds that allow the electrical stimulation of Schwann cells cultured on the scaffolds which increases the production of nerve growth factor (NGF).

  6. Poly lactic acid based injectable delivery systems for controlled release of a model protein, lysozyme.

    Science.gov (United States)

    Al-Tahami, Khaled; Meyer, Amanda; Singh, Jagdish

    2006-02-01

    The objective of this study was to evaluate the critical formulation parameters (i.e., polymer concentration, polymer molecular weight, and solvent nature) affecting the controlled delivery of a model protein, lysozyme, from injectable polymeric implants. The conformational stability and biological activity of the released lysozyme were also investigated. Three formulations containing 10%, 20%, and 30% (w/v) poly lactic acid (PLA) in triacetin were investigated. It was found that increasing polymer concentration in the formulations led to a lower burst effect and a slower release rate. Formulation with a high molecular weight polymer showed a greater burst effect as compared to those containing low molecular weight. Conformational stability and biological activity of released samples were studied by differential scanning calorimeter and enzyme activity assay, respectively. The released samples had significantly (P solution kept at same conditions). Increasing polymer concentration increased both the conformational stability and the biological activity of released lysozyme. In conclusion, phase sensitive polymer-based delivery systems were able to deliver a model protein, lysozyme, in a conformationally stable and biologically active form at a controlled rate over an extended period.

  7. Injectable In-Situ Gelling Controlled Release Drug Delivery System

    OpenAIRE

    Kulwant Singh; S. L. HariKumar

    2012-01-01

    The administration of poorly bioavailable drug through parenteral route is regarded the most efficient for drug delivery. Parenteral delivery provides rapid onset even for the drug with narrow therapeutic window, but to maintain the systemic drug level repeated installation are required which cause the patient discomfort. This can be overcome by designing the drug into a system, which control the drug release even through parenteral delivery, which improve patient compliance as well as pharma...

  8. Drug release control and system understanding of sucrose esters matrix tablets by artificial neural networks.

    Science.gov (United States)

    Chansanroj, Krisanin; Petrović, Jelena; Ibrić, Svetlana; Betz, Gabriele

    2011-10-09

    Artificial neural networks (ANNs) were applied for system understanding and prediction of drug release properties from direct compacted matrix tablets using sucrose esters (SEs) as matrix-forming agents for controlled release of a highly water soluble drug, metoprolol tartrate. Complexity of the system was presented through the effects of SE concentration and tablet porosity at various hydrophilic-lipophilic balance (HLB) values of SEs ranging from 0 to 16. Both effects contributed to release behaviors especially in the system containing hydrophilic SEs where swelling phenomena occurred. A self-organizing map neural network (SOM) was applied for visualizing interrelation among the variables and multilayer perceptron neural networks (MLPs) were employed to generalize the system and predict the drug release properties based on HLB value and concentration of SEs and tablet properties, i.e., tablet porosity, volume and tensile strength. Accurate prediction was obtained after systematically optimizing network performance based on learning algorithm of MLP. Drug release was mainly attributed to the effects of SEs, tablet volume and tensile strength in multi-dimensional interrelation whereas tablet porosity gave a small impact. Ability of system generalization and accurate prediction of the drug release properties proves the validity of SOM and MLPs for the formulation modeling of direct compacted matrix tablets containing controlled release agents of different material properties. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Slow-release fluoride devices for the control of dental decay.

    Science.gov (United States)

    Chong, Lee-Yee; Clarkson, Jan E; Dobbyn-Ross, Lorna; Bhakta, Smriti

    2018-03-01

    Slow-release fluoride devices have been investigated as a potentially cost-effective method of reducing dental caries in people with high risk of disease. This is the second update of the Cochrane Review first published in 2006 and previously updated in 2014. To evaluate the effectiveness and safety of different types of slow-release fluoride devices on preventing, arresting, or reversing the progression of carious lesions on all surface types of primary (deciduous) and permanent teeth. Cochrane Oral Health's Information Specialist searched the following electronic databases: Cochrane Oral Health's Trials Register (to 23 January 2018); the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 12) in the Cochrane Library (searched 23 January 2018); MEDLINE Ovid (1946 to 23 January 2018); and Embase Ovid (1980 to 23 January 2018). The US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials (23 January 2018). We placed no restrictions on the language or date of publication when searching the electronic databases. Parallel randomised controlled trials (RCTs) comparing slow-release fluoride devices with an alternative fluoride treatment, placebo, or no intervention in all age groups. The main outcome measures sought were changes in numbers of decayed, missing, and filled teeth or surfaces (DMFT/DMFS in permanent teeth or dmft/dmfs in primary teeth), and progression of carious lesions through enamel and into dentine. We conducted data collection and analysis using standard Cochrane review methods. At least two review authors independently performed all the key steps in the review such as screening of abstracts, application of inclusion criteria, data extraction, and risk of bias assessment. We resolved discrepancies through discussions or arbitration by a third or fourth review author. We found no evidence comparing slow-release

  10. Effect of crosslinking agents on chitosan microspheres in controlled release of diclofenac sodium

    OpenAIRE

    Gonçalves,Vanessa L.; Laranjeira,Mauro C. M.; Fávere,Valfredo T.; Pedrosa,Rozângela C.

    2005-01-01

    In this work chitosan microspheres were prepared by the simple coacervation method and crosslinked using epichlorhydrin or glutaraldehyde for the controlled release of diclofenac sodium. The effects of the crosslinking agents on chitosan microspheres over a 12-hour period were assessed with regard to swelling, hydrolysis, porosity, crosslinking, impregnation of diclofenac sodium (DS), and consequently to the release of DS in buffer solutions, simulating the gastrointestinal tract. The degree ...

  11. Releases of natural enemies in Hawaii since 1980 for classical biological control of weeds

    Science.gov (United States)

    P. Conant; J. N. Garcia; M. T. Johnson; W. T. Nagamine; C. K. Hirayama; G. P. Markin; R. L. Hill

    2013-01-01

    A comprehensive review of biological control of weeds in Hawaii was last published in 1992, covering 74 natural enemy species released from 1902 through 1980. The present review summarizes releases of 21 natural enemies targeting seven invasive weeds from 1981 to 2010. These projects were carried out by Hawaii Department of Agriculture (HDOA), USDA Forest Service (USFS...

  12. Clean Photothermal Heating and Controlled Release From Near Infrared Dye Doped Nanoparticles Without Oxygen Photosensitization

    Science.gov (United States)

    Guha, Samit; Shaw, Scott K.; Spence, Graeme T.; Roland, Felicia M.; Smith, Bradley D.

    2015-01-01

    The photothermal heating and release properties of biocompatible organic nanoparticles, doped with a near-infrared croconaine (Croc) dye, were compared with analogous nanoparticles doped with the common near-infrared dyes ICG and IR780. Separate formulations of lipid-polymer-hybrid nanoparticles and liposomes, each containing Croc dye, absorbed strongly at 808 nm and generated clean laser-induced heating (no production of 1O2 and no photobleaching of the dye). In contrast, laser-induced heating of nanoparticles containing ICG or IR780 produced reactive 1O2 leading to bleaching of the dye and also decomposition of co-encapsulated payload such as the drug Doxorubicin. Croc dye was especially useful as a photothermal agent for laser controlled release of chemically sensitive payload from nanoparticles. Solution state experiments demonstrated repetitive fractional release of water soluble fluorescent dye from the interior of thermosensitive liposomes. Additional experiments used a focused laser beam to control leakage from immobilized liposomes with very high spatial and temporal precision. The results indicate that fractional photothermal leakage from nanoparticles doped with Croc dye is a promising method for a range of controlled release applications. PMID:26149326

  13. Environmental Release Prevention and Control Plan

    International Nuclear Information System (INIS)

    Mamatey, A.; Arnett, M.

    1997-01-01

    During the history of SRS, continual improvements in facilities, process, and operations, and changes in the site''s mission have reduced the amount of radioactive liquid releases. In the early years of SRS (1958 to 1965), the amount of tritium discharged to the Savannah River averaged approximately 61,000 curies a year. During the mid-1980''s (1983 to 1988), liquid releases of tritium averaged 27,000 curies a year. By 1996, liquid releases of tritium are projected to be just 3000 curies for the year. This large projected decrease is the result of the planned shut-down of all reactors and the anticipated significant decline in the amount of tritium migrating from the site seepage basins and the Solid Waste Disposal Facility

  14. Controlled release of ketorolac through nanocomposite films of hydrogel and LDH nanoparticles

    International Nuclear Information System (INIS)

    Xu Zhiping; Gu Zi; Cheng Xiaoxi; Rasoul, Firas; Whittaker, Andrew K.; Lu Gaoqing Max

    2011-01-01

    A novel nanocomposite film for sustained release of anionic ophthalmic drugs through a double-control process has been examined in this study. The film, made as a drug-loaded contact lens, consists principally of a polymer hydrogel of 2-hydroxyethyl methacrylate (HEMA), in whose matrix MgAl-layered double hydroxide (MgAl-LDH) nanoparticles intercalated with the anionic drug are well dispersed. Such nanocomposite films (hydrogel-LDH-drug) contained 0.6–0.8 mg of MgAl-LDH and 0.08–0.09 mg of the ophthalmic drug (ketorolac) in 1.0 g of hydrogel. MgAl-drug-LDH nanoparticles were prepared with the hydrodynamic particle size of 40–200 nm. TEM images show that these nanoparticles are evenly dispersed in the hydrogel matrix. In vitro release tests of hydrogel-LDH-drug in pH 7.4 PBS solution at 32 °C indicate a sustained release profile of the loaded drug for 1 week. The drug release undergoes a rapid initial burst and then a monotonically decreasing rate up to 168 h. The initial burst release is determined by the film thickness and the polymerization conditions, but the following release rate is very similar, with the effective diffusion coefficient being nearly constant (3.0 × 10 −12 m 2 /s). The drug release from the films is mechanistically attributed to anionic exchange and the subsequent diffusion in the hydrogel matrix.

  15. Synthesis and characterization of a HAp-based biomarker with controlled drug release for breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    González, Maykel [Dept. of Molecular Engineering of Materials, Center of Applied Physics and Advanced Technology, National Autonomous University of Mexico (CFATA-UNAM), Boulevard Juriquilla 3001, Santiago de Querétaro, Querétaro 76230 (Mexico); Merino, Ulises [Dept. of Molecular Engineering of Materials, Center of Applied Physics and Advanced Technology, National Autonomous University of Mexico (CFATA-UNAM), Boulevard Juriquilla 3001, Santiago de Querétaro, Querétaro 76230 (Mexico); University of the Valley of Mexico (UVM), Boulevard Villas del Mesón 1000, Juriquilla, Santiago de Querétaro, Querétaro 76320 (Mexico); Vargas, Susana [Dept. of Molecular Engineering of Materials, Center of Applied Physics and Advanced Technology, National Autonomous University of Mexico (CFATA-UNAM), Boulevard Juriquilla 3001, Santiago de Querétaro, Querétaro 76230 (Mexico); Quintanilla, Francisco [University of the Valley of Mexico (UVM), Boulevard Villas del Mesón 1000, Juriquilla, Santiago de Querétaro, Querétaro 76320 (Mexico); Rodríguez, Rogelio, E-mail: rogelior@unam.mx [Dept. of Molecular Engineering of Materials, Center of Applied Physics and Advanced Technology, National Autonomous University of Mexico (CFATA-UNAM), Boulevard Juriquilla 3001, Santiago de Querétaro, Querétaro 76230 (Mexico)

    2016-04-01

    A biocompatible hybrid porous polymer–ceramic material was synthesized to be used as a biomarker in the treatment of breast cancer. This device was equipped with the capacity to release medicaments locally in a controlled manner. The biomaterial was Hydroxyapatite(HAp)-based and had a controlled pore size and pore volume fraction. It was implemented externally using a sharp end and a pair of barbed rings placed opposite each other to prevent relative movement once implanted. The biomarker was impregnated with cis-diamine dichloride platinum (II) [Cl{sub 2}-Pt-(NH{sub 3}){sub 2}]; the rate of release was obtained using inductively coupled plasma atomic emission spectroscopy (ICP-AES), and release occurred over the course of three months. Different release profiles were obtained as a function of the pore volume fraction. The biomaterial was characterized using scanning electron microscopy (SEM) and Raman spectroscopy. - Highlights: • A novel biocompatible hybrid porous polymer–ceramic material was synthesized. • The polymer–ceramic (HAp-based) material was used to prepare a biomarker. • The biomarker was impregnated with cis-diamine dichloride platinum (II). • The rate of cisplatin release was determined using inductively coupled plasma. • The kinetics of the cisplatin release was studied varying the biomarker porosity.

  16. Synthesis and characterization of a HAp-based biomarker with controlled drug release for breast cancer

    International Nuclear Information System (INIS)

    González, Maykel; Merino, Ulises; Vargas, Susana; Quintanilla, Francisco; Rodríguez, Rogelio

    2016-01-01

    A biocompatible hybrid porous polymer–ceramic material was synthesized to be used as a biomarker in the treatment of breast cancer. This device was equipped with the capacity to release medicaments locally in a controlled manner. The biomaterial was Hydroxyapatite(HAp)-based and had a controlled pore size and pore volume fraction. It was implemented externally using a sharp end and a pair of barbed rings placed opposite each other to prevent relative movement once implanted. The biomarker was impregnated with cis-diamine dichloride platinum (II) [Cl_2-Pt-(NH_3)_2]; the rate of release was obtained using inductively coupled plasma atomic emission spectroscopy (ICP-AES), and release occurred over the course of three months. Different release profiles were obtained as a function of the pore volume fraction. The biomaterial was characterized using scanning electron microscopy (SEM) and Raman spectroscopy. - Highlights: • A novel biocompatible hybrid porous polymer–ceramic material was synthesized. • The polymer–ceramic (HAp-based) material was used to prepare a biomarker. • The biomarker was impregnated with cis-diamine dichloride platinum (II). • The rate of cisplatin release was determined using inductively coupled plasma. • The kinetics of the cisplatin release was studied varying the biomarker porosity.

  17. Workload control and order release : A lean solution for make-to-order companies

    NARCIS (Netherlands)

    Thurer, M.; Stevenson, M.; Silva, C.; Land, M.J.; Fredendall, L.D.

    2012-01-01

    Protecting throughput from variance is the key to achieving lean. Workload control (WLC) accomplishes this in complex make-to-order job shops by controlling lead times, capacity, and work-in-process (WIP). However, the concept has been dismissed by many authors who believe its order release

  18. Qualitative analysis of controlled release ciprofloxacin/carbopol 934 mucoadhesive suspension

    Directory of Open Access Journals (Sweden)

    Subhashree Sahoo

    2011-01-01

    Full Text Available Mucoadhesive polymeric (carbopol 934 suspension of ciprofloxacin was prepared by ultrasonication and optimized with the aim of developing an oral controlled release gastro-retentive dosage form. The qualitative analysis of the formulation was performed by fourier transform infrared spectroscopy (FTIR, Raman spectroscopy, X-ray powder diffraction (XRD, and scanning electron microscopy (SEM analyses. FTIR (400 cm-1 to 4000 cm-1 region and Raman (140 to 2400 cm-1 region Spectroscopic studies were carried out and the spectra were used for interpretation. XRD data of pure drug, polymer and the formulation were obtained using a powder diffractometer scanned from a Bragg′s angle (2q of 10° to 70°. The dispersion of the particle was observed using SEM techniques. The particle size distribution and aspect ratio of particles in the polymeric suspension were obtained from SEM image analysis. The results from FTIR and Raman spectroscopic analyses suggested that, in formulation, the carboxylic groups of ciprofloxacin and hydroxyl groups of C934 undergo a chemical interaction leading to esterification and hydrogen bonding. The XRD data suggested that the retention of crystalline nature of ciprofloxacin in the formulation would lead to increase in stability and drug loading; decrease in solubility; and delay in release of the drug from polymeric suspension with better bioavailability and penetration capacity. The SEM image analysis indicated that, in the formulation maximum particles were having aspect ratio from 2 to 4 and standard deviation was very less which provided supporting evidences for homogeneous, uniformly dispersed, stable controlled release ciprofloxacin suspension which would be pharmaceutically acceptable.

  19. Acid-Labile Acyclic Cucurbit[n]uril Molecular Containers for Controlled Release.

    Science.gov (United States)

    Mao, Dake; Liang, Yajun; Liu, Yamin; Zhou, Xianhao; Ma, Jiaqi; Jiang, Biao; Liu, Jia; Ma, Da

    2017-10-02

    Stimuli-responsive molecular containers are of great importance for controlled drug delivery and other biomedical applications. A new type of acid labile acyclic cucurbit[n]uril (CB[n]) molecular containers is presented that can degrade and release the encapsulated cargo at accelerated rates under mildly acidic conditions (pH 5.5-6.5). These containers retain the excellent recognition properties of CB[n]-type hosts. A cell culture study demonstrated that the cellular uptake of cargos could be fine-tuned by complexation with different containers. The release and cell uptake of cargo dye was promoted by acidic pH. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Phytosterol-based oleogels self-assembled with monoglyceride for controlled volatile release.

    Science.gov (United States)

    Yang, Dan-Xia; Chen, Xiao-Wei; Yang, Xiao-Quan

    2018-01-01

    Oleogels have recently emerged as a subject of growing interest among industrial and academic researchers as an alternative to saturated/trans-fat and delivery of functional ingredients. Phytosterols, comprising plant-derived natural steroid compounds, are preferred for oleogel production because they are both natural and healthy. In the present study, phytosterol-based oleogels self-assembled with monoglyceride were studied with respect to tuning volatile release. Microscopy images of the bicomponent oleogels of β-sitosterol and monoglyceride showed the formation of a new three-dimensional network of entangled crystals and a controllable microstructure. Our analysis from differential scanning calorimetry and small angle X-ray scattering results suggests the self-assembly of β-sitosterol and monoglyceride via intermolecular hydrogen bonds into spherulitic microstructures. The results showed that the release rate (v 0 ), maximum headspace concentrations (C max ) and partition coefficients (k a/o ) for oleogels showed a significantly controlled release and were tunable via the microstructure of phytosterol-based oleogels under both dynamic and static conditions. In addition, the solid-like oleogels had interesting thixotropic and thermoresponsive behaviors, probably as a result of intermolecular hydrogen bonding. The self-assembly of phytosterol-based oleogels with monoglyceride was attributed to intermolecular hydrogen and is demonstrated to be a promising tunable and functional strategy for delivering flavor compounds. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  1. Simultaneous Intercalation of 1-Naphthylacetic Acid and Indole-3-butyric Acid into Layered Double Hydroxides and Controlled Release Properties

    Directory of Open Access Journals (Sweden)

    Shifeng Li

    2014-01-01

    Full Text Available Controlled release formulations have been shown to have potential in overcoming the drawbacks of conventional plant growth regulators formulations. A controlled-release formulation of 1-naphthylacetic acid (NAA and indole-3-butyric acid (IBA simultaneous intercalated MgAl-layered double hydroxides (LDHs was prepared. The synthetic nanohybrid material was characterized by various techniques, and release kinetics was studied. NAA and IBA anions located in the gallery of MgAl-LDHs with bilayer arrangement, and the nanohybrids particles were of typical plate-like shape with the lateral size of 50–100 nm. The results revealed that NAA and IBA have been intercalated into the interlayer spaces of MgAl-LDHs. The release of NAA and IBA fits pseudo-second-order model and is dependent on temperature, pH value, and release medium. The nanohybrids of NAA and IBA simultaneously intercalated in LDHs possessed good controlled release properties.

  2. Controlling insulin release from reverse hexagonal (HII) liquid crystalline mesophase by enzymatic lipolysis.

    Science.gov (United States)

    Mishraki-Berkowitz, Tehila; Cohen, Guy; Aserin, Abraham; Garti, Nissim

    2018-01-01

    In the present study we aimed to control insulin release from the reverse hexagonal (H II ) mesophase using Thermomyces lanuginosa lipase (TLL) in the environment (outer TLL) or within the H II cylinders (inner TLL). Two insulin-loaded systems differing by the presence (or absence) of phosphatidylcholine (PC) were examined. In general, incorporation of PC into the H II interface (without TLL) increased insulin release, as a more cooperative system was formed. Addition of TLL to the systems' environments resulted in lipolysis of the H II structure. In the absence of PC, the lipolysis was more dominant and led to a significant increase in insulin release (50% after 8h). However, the presence of PC stabilized the interface, hindering the lipolysis, and therefore no impact on the release profile was detected during the first 8h. Entrapment of TLL within the H II cylinders (with and without PC) drastically increased insulin release in both systems up to 100%. In the presence of PC insulin released faster and the structure was more stable. Consequently, the presence of lipases (inner or outer) both enhanced the destruction of the carrier, and provided sustained release of the entrapped insulin. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Toxic vapor concentrations in the control room following a postulated accidental release

    International Nuclear Information System (INIS)

    Wing, J.

    1979-05-01

    An acceptable method is presented for calculating the vapor concentrations in a control room as a function of time after a postulated accidental release. Included are the mathematical formulas for computing the rates of vaporization and evaporation of liquid spills, the vapor dispersion in air, and the control room air exchange. A list of toxic chemicals and their physical properties is also given

  4. Controlled release and intracellular protein delivery from mesoporous silica nanoparticles.

    Science.gov (United States)

    Deodhar, Gauri V; Adams, Marisa L; Trewyn, Brian G

    2017-01-01

    Protein therapeutics are promising candidates for disease treatment due to their high specificity and minimal adverse side effects; however, targeted protein delivery to specific sites has proven challenging. Mesoporous silica nanoparticles (MSN) have demonstrated to be ideal candidates for this application, given their high loading capacity, biocompatibility, and ability to protect host molecules from degradation. These materials exhibit tunable pore sizes, shapes and volumes, and surfaces which can be easily functionalized. This serves to control the movement of molecules in and out of the pores, thus entrapping guest molecules until a specific stimulus triggers release. In this review, we will cover the benefits of using MSN as protein therapeutic carriers, demonstrating that there is great diversity in the ways MSN can be used to service proteins. Methods for controlling the physical dimensions of pores via synthetic conditions, applications of therapeutic protein loaded MSN materials in cancer therapies, delivering protein loaded MSN materials to plant cells using biolistic methods, and common stimuli-responsive functionalities will be discussed. New and exciting strategies for controlled release and manipulation of proteins are also covered in this review. While research in this area has advanced substantially, we conclude this review with future challenges to be tackled by the scientific community. Copyright © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Effect of crosslinking agents on chitosan microspheres in controlled release of diclofenac sodium

    Directory of Open Access Journals (Sweden)

    Vanessa L. Gonçalves

    2005-03-01

    Full Text Available In this work chitosan microspheres were prepared by the simple coacervation method and crosslinked using epichlorhydrin or glutaraldehyde for the controlled release of diclofenac sodium. The effects of the crosslinking agents on chitosan microspheres over a 12-hour period were assessed with regard to swelling, hydrolysis, porosity, crosslinking, impregnation of diclofenac sodium (DS, and consequently to the release of DS in buffer solutions, simulating the gastrointestinal tract. The degree of swelling varied with the pH for glutaraldehyde chitosan microspheres (GCM and epichlorhydrin chitosan microspheres (ECM. Partial acid and basic hydrolysis affected the swelling behavior of the GCM matrix. Release kinetics of diclofenac sodium from these matrices were investigated at pH 1.2, 6.8 and 9.0, simulating the gastrointestinal tract conditions. The results indicated that the release mechanism deviated slightly from Fickian transport.

  6. Evaluation of Controlled Release Urea on the Dynamics of Nitrate, Ammonium, and Its Nitrogen Release in Black Soils of Northeast China

    Directory of Open Access Journals (Sweden)

    Xin Tong

    2018-01-01

    Full Text Available Controlled release urea (CRU is considered to enhance crop yields while alleviating negative environmental problems caused by the hazardous gas emissions that are associated with high concentrations of ammonium (NH4+ and nitrate (NO3− in black soils. Short-term effects of sulfur-coated urea (SCU and polyurethane-coated urea (PCU, compared with conventional urea, on NO3− and NH4+ in black soils were studied through the buried bag experiment conducted in an artificial climate chamber. We also investigated nitrogen (N release kinetics of CRU and correlations between the cumulative N release rate and concentrations of NO3− and NH4+. CRU can reduce concentrations of NO3− and NH4+, and PCU was more effective in maintaining lower soil NO3−/NH4+ ratios than SCU and U. Parabolic equation could describe the kinetics of NO3− and NH4+ treated with PCU. The Elovich equation could describe the kinetics of NO3− and NH4+ treated with SCU. The binary linear regression model was established to predict N release from PCU because of significant correlations between the cumulative N release rate and concentrations of NO3− and NH4+. These results provided a methodology and data support for characterizing and predicting the N release from PCU in black soils.

  7. Electrode effects of a cellulose-based electro-active paper energy harvester

    International Nuclear Information System (INIS)

    Abas, Zafar; Kim, Heung Soo; Zhai, Lindong; Kim, Jaehwan; Kim, Joo-Hyung

    2014-01-01

    The possibility of cellulose-based electro-active paper (EAPap) as a vibrational energy transducer was investigated in this paper. Thin cellulose EAPap film specimens were prepared by the regenerating process. Three different metal electrodes of gold, silver and aluminum were deposited on a 50 × 50 mm 2 cellulose film using a thermal evaporator. An aluminum cantilever beam was used as a vibrational bender and EAPap was attached close to the root of the cantilever beam. The voltage output of the EAPap was measured under harmonic base excitation of the cantilever beam. The EAPap with aluminum electrode provided the largest open circuit voltage output compared to those with gold or silver electrodes. The output voltages of the EAPap increased linearly with increase of the area of the electrodes. The output voltages also increased with increasing input acceleration but became saturated at a certain magnitude. From the experimental results, we conclude that EAPap with metal electrodes can be used as a flexible energy harvesting transducer by external mechanical stress, and the output voltage is related to the electrode material due to its work function. (paper)

  8. Electroactive Tissue Scaffolds with Aligned Pores as Instructive Platforms for Biomimetic Tissue Engineering

    Directory of Open Access Journals (Sweden)

    John G. Hardy

    2015-01-01

    Full Text Available Tissues in the body are hierarchically structured composite materials with tissue-specific chemical and topographical properties. Here we report the preparation of tissue scaffolds with macroscopic pores generated via the dissolution of a sacrificial supramolecular polymer-based crystal template (urea from a biodegradable polymer-based scaffold (polycaprolactone, PCL. Furthermore, we report a method of aligning the supramolecular polymer-based crystals within the PCL, and that the dissolution of the sacrificial urea yields scaffolds with macroscopic pores that are aligned over long, clinically-relevant distances (i.e., centimeter scale. The pores act as topographical cues to which rat Schwann cells respond by aligning with the long axis of the pores. Generation of an interpenetrating network of polypyrrole (PPy and poly(styrene sulfonate (PSS in the scaffolds yields electroactive tissue scaffolds that allow the electrical stimulation of Schwann cells cultured on the scaffolds which increases the production of nerve growth factor (NGF.

  9. Controlled release of biofunctional substances by radiation-induced polymerization

    International Nuclear Information System (INIS)

    Yoshida, M.; Kumakura, M.; Kaetsu, I.

    1978-01-01

    The release behaviour of a drug from flat circular capsules obtained by radiation-induced polymerization at low temperatures and with different hydrophilic properties has been studied. The effect of various factors on release property was investigated. The release process could be divided into three parts, an initial quick release stage, stationary state release stage and a retarded release stage. Release behaviour in the stationary state was examined using Noyes-Whitney and Higuchi equations. It was shown that the hydrophilic property of polymer matrix expressed by water content was the most important effect on diffusion and release rate. Rigidity of the polymer may also affect diffusivity. The first quick release step could be attributed to rapid dissolution of drug in the matrix surface due to polymer swelling. (author)

  10. Water - The radiological health of rivers: releases are very much controlled downstream power plants. What do hospital releases represent? The Seine reserves a surprise

    International Nuclear Information System (INIS)

    Anon.

    2015-01-01

    After a brief presentation of the role of the IRSN in the control of the radioactivity present in waters and in the control and follow-up of all sources of radioactivity, a first article briefly present the hydro-collector network, indicates that some point samplings of sediment and aquatic species are performed, that a national network of beacons for a continuous radioactivity measurement is installed in the main French rivers, downstream nuclear installations, and that advanced measurement techniques are used to detect very small level of tritium. Maps giving a brief indication of the radiological condition of the Loire and Rhone are provided. A second article addresses the control of releases downstream power plants, and evokes the legal context and the associated objectives and produced documents. The third article discusses the risk associated with hospital wastes and releases (liquid and solid effluents), how radioactivity is controlled between the hospital and tap water distribution. The last article reports and comments the results obtained by an analysis of historical pollutions trapped in the sediments of the Seine: 40 year-old traces of plutonium have been discovered, due to an accidental release from a CEA installation in Fontenay-aux-Roses, with no detrimental impact on population or on sewer workers

  11. Synthesis of hydrogels of alginate for system controlled release of progesterone

    International Nuclear Information System (INIS)

    Abreu, Marlon de F.; Rodriguez, Ruben J.S.; Silva, Ester C.C. da; Barreto, Gabriela N.S.

    2015-01-01

    The chemical modifications of natural polymers like alginate, has allowed the development of new formulations for controlled release systems. In this work we report the synthesis of a derivative of the amidic alginate with alkyl chain. The polymer was characterized by spectroscopic techniques: Nuclear Magnetic Resonance and Fourier Transform Infrared. (author)

  12. Electroactive ionic liquids based on 2,5-ditert-butyl-1,4-dimethoxybenzene and triflimide anion as redox shuttle for Li4Ti5O12/LiFePO4 lithium-ion batteries

    Science.gov (United States)

    Gélinas, Bruno; Bibienne, Thomas; Dollé, Mickael; Rochefort, Dominic

    2017-12-01

    In order to increase the solubility and oxidation potential of redox shuttles, electroactive ionic liquids (RILs) based on the modification of 1,4-dimethoxybenzene with triflimide anions were synthesized. We developed two synthetic routes to obtain these RILs in which the triflimide was either linked on the benzene ring or as a ether on 2,5-ditert-butyl-1,4-dimethoxybenzene (DDB). These RILs all have melting points below 100 °C, but above room temperature. The structural impact of electroactive anion was evaluated in this study by determining the redox potential and electrochemical stability. The electrochemical properties of these RILs were investigated by cyclic voltammetry and the diffusion coefficients were measured by double potential step chronoamperometry. The viscosity and ionic conductivity measurements of redox-active electrolyte were obtained at different temperatures and the RIL additives are shown to have a low impact on these electrolyte properties at concentrations up to 0.3 M. The charge-overcharge-discharge cycles of Li/LiFePO4 half-cells and Li4Ti5O12/LiFePO4 full cells with a 100% overcharge are presented using redox-active electrolyte (0.3 M concentration level) at 0.1 C rate. This study highlights the potential of electroactive ionic liquids as highly soluble and stable functional additives in Li-ion battery electrolytes.

  13. A prominent anchoring effect on the kinetic control of drug release from mesoporous silica nanoparticles (MSNs).

    Science.gov (United States)

    Tran, Vy Anh; Lee, Sang-Wha

    2018-01-15

    This work demonstrated kinetically controlled release of model drugs (ibuprofen, FITC) from well-tailored mesoporous silica nanoparticles (MSNs) depending on the surface charges and molecular sizes of the drugs. The molecular interactions between entrapped drugs and the pore walls of MSNs controlled the release of the drugs through the pore channels of MSNs. Also, polydopamine (PDA) layer-coated MSNs (MSNs@PDA) was quite effective to retard the release of large FITC, in contrast to a slight retardation effect on relatively small Ibuprofen. Of all things, FITC (Fluorescein isothiocyanate)-labeled APTMS (3-aminopropyltrimethoxysilane) (APTMS-FITC conjugates) grafted onto the MSNs generate a pinch-effect on the pore channel (so-called a prominent anchoring effect), which was highly effective in trapping (or blocking) drug molecules at the pore mouth of the MSNs. The anchored APTMS-FITC conjugates provided not only tortuous pathways to the diffusing molecules, but also sustained release of the ibuprofen over a long period of time (∼7days). The fast release kinetics was predicted by an exponential equation based on Fick's law, while the slow release kinetics was predicted by Higuchi model. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Enantioselectively controlled release of chiral drug (metoprolol) using chiral mesoporous silica materials

    Energy Technology Data Exchange (ETDEWEB)

    Guo Zhen; Liu Xianbin; Ng, Siu-Choon; Chen Yuan; Yang Yanhui [School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459 (Singapore); Du Yu, E-mail: du_yu@jlu.edu.cn, E-mail: yhyang@ntu.edu.sg [College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China)

    2010-04-23

    Chiral porous materials have attracted burgeoning attention on account of their potential applications in many areas, such as enantioseparation, chiral catalysis, chemical sensors and drug delivery. In this report, chiral mesoporous silica (CMS) materials with various pore sizes and structures were prepared using conventional achiral templates (other than chiral surfactant) and a chiral cobalt complex as co-template. The synthesized CMS materials were characterized by x-ray diffraction, nitrogen physisorption, scanning electron microscope and transmission electron microscope. These CMS materials, as carriers, were demonstrated to be able to control the enantioselective release of a representative chiral drug (metoprolol). The release kinetics, as modeled by the power law equation, suggested that the release profiles of metoprolol were remarkably dependent on the pore diameter and pore structure of CMS materials. More importantly, R- and S-enantiomers of metoprolol exhibited different release kinetics on CMS compared to the corresponding achiral mesoporous silica (ACMS), attributable to the existence of local chirality on the pore wall surface of CMS materials. The chirality of CMS materials on a molecular level was further substantiated by vibrational circular dichroism measurements.

  15. Enantioselectively controlled release of chiral drug (metoprolol) using chiral mesoporous silica materials

    International Nuclear Information System (INIS)

    Guo Zhen; Liu Xianbin; Ng, Siu-Choon; Chen Yuan; Yang Yanhui; Du Yu

    2010-01-01

    Chiral porous materials have attracted burgeoning attention on account of their potential applications in many areas, such as enantioseparation, chiral catalysis, chemical sensors and drug delivery. In this report, chiral mesoporous silica (CMS) materials with various pore sizes and structures were prepared using conventional achiral templates (other than chiral surfactant) and a chiral cobalt complex as co-template. The synthesized CMS materials were characterized by x-ray diffraction, nitrogen physisorption, scanning electron microscope and transmission electron microscope. These CMS materials, as carriers, were demonstrated to be able to control the enantioselective release of a representative chiral drug (metoprolol). The release kinetics, as modeled by the power law equation, suggested that the release profiles of metoprolol were remarkably dependent on the pore diameter and pore structure of CMS materials. More importantly, R- and S-enantiomers of metoprolol exhibited different release kinetics on CMS compared to the corresponding achiral mesoporous silica (ACMS), attributable to the existence of local chirality on the pore wall surface of CMS materials. The chirality of CMS materials on a molecular level was further substantiated by vibrational circular dichroism measurements.

  16. New Incremental Actuators based on Electro-active Polymer: Conceptual, Control, and Driver Design Considerations

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Schneider, Henrik; Zhang, Zhe

    2016-01-01

    This paper presents an overview of the widely usedconventional linear actuator technologies and existing electroactivepolymer based linear and rotary actuators. It also providesthe conceptual, control and driver design considerations for anew dielectric electro-active polymer (DEAP) based...

  17. Timing of insertion of levonorgestrel-releasing intrauterine system : a randomised controlled trial

    NARCIS (Netherlands)

    van der Heijden, Pahh; Geomini, Pmaj; Herman, M C; Veersema, S; Bongers, M Y

    OBJECTIVE: The objective was to assess whether patient-perceived pain during the insertion of the levonorgestrel-releasing intrauterine system (LNG-IUS) depends on the timing during the menstrual cycle. DESIGN: A stratified two-armed non-inferiority randomised controlled trial. SETTING: Large

  18. Preparation and controlled release of mesoporous MCM-41/propranolol hydrochloride composite drug.

    Science.gov (United States)

    Zhai, Qing-Zhou

    2013-01-01

    This article used MCM-41 as a carrier for the assembly of propranolol hydrochloride by the impregnation method. By means of chemical analysis, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and low-temperature N(2) adsorption-desorption at 77 K, the characterization was made for the prepared materials. The propranolol hydrochloride guest assembly capacity was 316.20 ± 0.31 mg/g (drug/MCM-41). Powder XRD test results indicated that during the process of incorporation, the frameworks of the MCM-41 were not destroyed and the crystalline degrees of the host-guest nanocomposite materials prepared still remained highly ordered. Characterization by SEM and TEM showed that the composite material presented spherical particle and the average particle size of composite material was 186 nm. FT-IR spectra showed that the MCM-41 framework existed well in the (MCM-41)-propranolol hydrochloride composite. Low-temperature nitrogen adsorption-desorption results at 77 K showed that the guest partially occupied the channels of the molecular sieves. Results of the release of the prepared composite drug in simulated body fluid indicated that the drug can release up to 32 h and its maximum released amount was 99.20 ± 0.11%. In the simulated gastric juice release pattern of drug, the maximum time for the drug release was discovered to be 6 h and the maximum cumulative released amount of propranolol hydrochloride was 45.13 ± 0.23%. The drug sustained-release time was 10 h in simulated intestinal fluid and the maximum cumulative released amount was 62.05 ± 0.13%. The prepared MCM-41 is a well-controlled drug delivery carrier.

  19. Characterization of hybrid microparticles/Montmorillonite composite with raspberry-like morphology for Atorvastatin controlled release.

    Science.gov (United States)

    García-Guzmán, Perla; Medina-Torres, Luis; Calderas, Fausto; Bernad-Bernad, María Josefa; Gracia-Mora, Jesús; Mena, Baltasar; Manero, Octavio

    2018-07-01

    In this work, we prepared a novel composite based on hybrid gelatin carriers and montmorillonite clay (MMT) to analyze its viability as controlled drug delivery system. The objective of this research involves the characterization of composites formed by structured lipid-gelatin micro-particles (MP) and MMT clay. This analysis included the evaluation of the composite according to its rheological properties, morphology (SEM), particle size, XRD, FT-IR, and in vitro drug release. The effect of pH in the properties of the composite is evaluated. A novel raspberry-like or armor MP/MMT clay composite is reported, in which the pH has an important effect on the final structure of the composite for ad-hoc drug delivery systems. For pH values below the isoelectric point, we obtained defined morphologies with entrapment efficiencies up to 67%. The pH level controls the MP/MMT composite release mechanism, restringing drug release in the stomach-like environment. Intended for oral administration, these results evidence that the MP/MMT composite represents an attractive alternative for intestinal-colonic controlled drug delivery systems. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Controlled release of free-falling test models

    Science.gov (United States)

    Fife, W. J.; Holway, H. P.

    1970-01-01

    Releasing device, powered by a drill motor through an adjustable speed reducer, has a spinning release head with three retractable spring-loaded fingers. The fingers are retracted by manual triggering of a cable at the motor end of the unit.

  1. Electromechanical stability of electro-active silicone filled with high permittivity particles undergoing large deformation

    International Nuclear Information System (INIS)

    Liu, Liwu; Liu, Yanju; Zhang, Zhen; Leng, Jinsong; Li, Bo

    2010-01-01

    In this paper, an expression for the permittivity of electro-active silicone undergoing large deformation with high permittivity particles filled uniformly has been proposed. Two expressions are proposed for the permittivity, one based on experimental tests and the other based on the theory of composite material. By applying the thermodynamic model incorporating linear dielectric permittivity and nonlinear hyperelastic performance, the mechanical performance and electromechanical stability of the coupling system constituted by silicone filled with PMN–PT have been studied. The results show that the critical electric field decreases, namely the stability performance of the system declines when the content of PMN–PT c(v) increases and the electrostrictive coefficients increase. The results are beneficial for us to understand deeply the influence of the filled particle on the stability performance of silicone and to guide the design and manufacture of actuators and sensors based on dielectric elastomers

  2. Electric-field triggered controlled release of bioactive volatiles from imine-based liquid crystalline phases.

    Science.gov (United States)

    Herrmann, Andreas; Giuseppone, Nicolas; Lehn, Jean-Marie

    2009-01-01

    Application of an electric field to liquid crystalline film forming imines with negative dielectric anisotropy, such as N-(4-methoxybenzylidene)-4-butylaniline (MBBA, 1), results in the expulsion of compounds that do not participate in the formation of the liquid crystalline phase. Furthermore, amines and aromatic aldehydes undergo component exchange with the imine by generating constitutional dynamic libraries. The strength of the electric field and the duration of its application to the liquid crystalline film influence the release rate of the expelled compounds and, at the same time, modulate the equilibration of the dynamic libraries. The controlled release of volatile organic molecules with different chemical functionalities from the film was quantified by dynamic headspace analysis. In all cases, higher headspace concentrations were detected in the presence of an electric field. These results point to the possibility of using imine-based liquid crystalline films to build devices for the controlled release of a broad variety of bioactive volatiles as a direct response to an external electric signal.

  3. A REVIEW ON CONTROLLED DRUG RELEASE FORMULATION: SPANSULES

    OpenAIRE

    Rinky Maurya; Dr. Pramod Kumar Sharma; Rishabha Malviya

    2014-01-01

    Spansules are a dosage form which was considered as one of the Advanced Drug Delivery System. Multidrug preparations can be delivered easily by spansules or granules in capsule technology. This type of delivery system designed to release a drug or a medicament at two or more different rates or in different span of time. A quick/slow release system provides an initial release of drug followed by a constant rate of drug release over a extended period or a defined period of time and in slow/quic...

  4. Effect of PPG-PEG-PPG on the tocopherol-controlled release from films intended for food-packaging applications.

    Science.gov (United States)

    Castro López, María del Mar; Dopico García, Sonia; Ares Pernas, Ana; López Vilariño, José Manuel; González Rodríguez, María Victoria

    2012-08-22

    The feasibility of novel controlled release systems for the delivery of active substances from films intended for food packaging was investigated. Because polyolefins are used highly for food-packaging applications, the reported high retention degree of antioxidants has limited their use for active packaging. Thus, in this study, PP films modified with different chain extenders have been developed to favor and control the release rates of the low molecular weight antioxidant tocopherol. The use of different chain extenders as polymer modifiers (PE-PEG M(w), 575; and PPG-PEG-PPG M(w), 2000) has caused significant changes in tocopherol-specific release properties. High-performance liquid chromatography coupled to PDA-FL and PDA-MS was used to test tocopherol and chain extender migration, respectively. The release of tocopherol from the prepared films with two chain extenders into two food simulants was studied. Different temperatures and storage times were also tested. Varying the structural features of the films with the incorporation of different levels of PPG-PEG-PPG, the release of tocopherol (food-packaging additive) into different ethanolic simulants could be clearly controlled. The effect of the temperature and storage time on the release of the antioxidant has been outstanding as their values increased. The migration of the chain extender, also tested, was well below the limits set by European legislation.

  5. Effects of Controlled-Release Urea on Grain Yield of Spring Maize, Nitrogen Use Efficiency and Nitrogen Balance

    Directory of Open Access Journals (Sweden)

    JI Jing-hong

    2017-03-01

    Full Text Available The effects of mixing controlled-released urea (CRU (release period of resin coated urea is 90 days and urea (U on maize yield, nitrogen use efficiency and nitrogen balance were studied by 4 plot experiments (site:Shuangcheng, Binxian, Harbin and Zhaoyuan in two years (from year 2011 to 2012 to clarify the effect of controlled release urea on spring maize and soil nitrogen balance. Results were as follow:Spring maize yield and nitrogen absorption were increased with the increasing nitrogen fertilizer. Compared with applying urea treatment, applying CRU could increase yield, nitrogen absorption, nitrogen use efficiency, agriculture efficiency of nitrogen and nitrogen contribution rate. Under the same amount of nitrogen (100%, 75%, 50%, compared with 100% U as basic fertilizer treatment, maize yield of 100% CRU treatment increased 391, 427, 291 kg·hm-2, nitrogen use efficiency increased by 5.9%,4.9% and 5.1%, agriculture efficiency of nitrogen increased 2.0, 2.6, 2.6 kg·kg-1, and nitrogen contribution rate increased 2.7%, 3.1% and 2.4%, respectively. The value of maize yield, nitrogen absorption, nitrogen use efficiency and agriculture efficiency of nitrogen between the treatment four (40% urea as basic fertilizer+60% urea as topdressing and treatment five (40% urea plus 60% controlled release urea as basic fertilizer were similar. Apparent profit and loss of nitrogen decreased with the increase of nitrogen nitrogen fertilizer. Nitrogen apparent loss by applying 100% controlled release urea was reduced of 15.0 kg·hm-2 than applying 100% U treatment;Nitrogen apparent loss amount was decreased of 23.9 kg·hm-2 under treatment five. The method of mixing 40% urea and 60% controlled release urea should be applied in maize production in Heilongjiang Province.

  6. Externally controlled on-demand release of anti-HIV drug using magneto-electric nanoparticles as carriers.

    Science.gov (United States)

    Nair, Madhavan; Guduru, Rakesh; Liang, Ping; Hong, Jeongmin; Sagar, Vidya; Khizroev, Sakhrat

    2013-01-01

    Although highly active anti-retroviral therapy has resulted in remarkable decline in the morbidity and mortality in AIDS patients, inadequately low delivery of anti-retroviral drugs across the blood-brain barrier results in virus persistence. The capability of high-efficacy-targeted drug delivery and on-demand release remains a formidable task. Here we report an in vitro study to demonstrate the on-demand release of azidothymidine 5'-triphosphate, an anti-human immunodeficiency virus drug, from 30 nm CoFe2O4@BaTiO3 magneto-electric nanoparticles by applying a low alternating current magnetic field. Magneto-electric nanoparticles as field-controlled drug carriers offer a unique capability of field-triggered release after crossing the blood-brain barrier. Owing to the intrinsic magnetoelectricity, these nanoparticles can couple external magnetic fields with the electric forces in drug-carrier bonds to enable remotely controlled delivery without exploiting heat. Functional and structural integrity of the drug after the release was confirmed in in vitro experiments with human immunodeficiency virus-infected cells and through atomic force microscopy, spectrophotometry, Fourier transform infrared and mass spectrometry studies.

  7. Regulating the path from legacy recognition, through recovery to release from regulatory control.

    Science.gov (United States)

    Sneve, Malgorzata Karpow; Smith, Graham

    2015-04-01

    Past development of processes and technologies using radioactive material led to construction of many facilities worldwide. Some of these facilities were built and operated before the regulatory infrastructure was in place to ensure adequate control of radioactive material during operation and decommissioning. In other cases, controls were in place but did not meet modern standards, leading to what is now considered to have been inadequate control. Accidents and other events have occurred resulting in loss of control of radioactive material and unplanned releases to the environment. The legacy from these circumstances is that many countries have areas or facilities at which abnormal radiation conditions exist at levels that give rise to concerns about environmental and human health of potential interest to regulatory authorities. Regulation of these legacy situations is complex. This paper examines the regulatory challenges associated with such legacy management and brings forward suggestions for finding the path from: legacy recognition; implementation, as necessary, of urgent mitigation measures; development of a longer-term management strategy, through to release from regulatory control. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. Formulation and Pharmacokinetic Evaluation of Controlled-Release ...

    African Journals Online (AJOL)

    The effect of several formulation variables on in ... The in vivo pharmacokinetics of the optimized formulation was compared ... Results: The core tablets exhibited extended release consisting of drug release from the embedded ... important factor in medical treatment with respect ... The solvents for high-performance liquid.

  9. Controlled antiseptic/eosin release from chitosan-based hydrogel modified fibrous substrates.

    Science.gov (United States)

    Romano, Ilaria; Ayadi, Farouk; Rizzello, Loris; Summa, Maria; Bertorelli, Rosalia; Pompa, Pier Paolo; Brandi, Fernando; Bayer, Ilker S; Athanassiou, Athanassia

    2015-10-20

    Fibers of cellulose networks were stably coated with N-methacrylate glycol chitosan (MGC) shells using subsequent steps of dip coating and photo-curing. The photo-crosslinked MGC-coated cellulose networks preserved their fibrous structure. A model hydrophilic antiseptic solution containing eosin, chloroxylenol and propylene glycol was incorporated into the shells to study the drug release dynamics. Detailed drug release mechanism into phosphate buffered saline (PBS) solutions from coated and pristine fibers loaded with the antiseptic was investigated. The results show that the MGC-coated cellulose fibers enable the controlled gradual release of the drug for four days, as opposed to fast, instantaneous release from eosin coated pristine fibers. This release behavior was found to affect the antibacterial efficiency of the fibrous cellulose sheets significantly against Staphylococcus aureus and Candida albicans. In the case of the MGC-eosin functionalized system the antibacterial efficiency was as high as 85% and 90%, respectively, while for the eosin coated pristine cellulose system the efficiency was negative, indicating bacterial proliferation. Furthermore, the MGC-eosin system was shown to be efficacious in a model of wound healing in mice, reducing the levels of various pro-inflammatory cytokines that modulate early inflammatory phase responses. The results demonstrate good potential of these coated fibers for wound dressing and healing applications. Due to its easy application on common passive commercial fibrous dressings such as gauzes and cotton fibers, the method can render them active dressings in a cost effective way. Copyright © 2015. Published by Elsevier Ltd.

  10. Accelerated in-vitro release testing methods for extended-release parenteral dosage forms.

    Science.gov (United States)

    Shen, Jie; Burgess, Diane J

    2012-07-01

    This review highlights current methods and strategies for accelerated in-vitro drug release testing of extended-release parenteral dosage forms such as polymeric microparticulate systems, lipid microparticulate systems, in-situ depot-forming systems and implants. Extended-release parenteral dosage forms are typically designed to maintain the effective drug concentration over periods of weeks, months or even years. Consequently, 'real-time' in-vitro release tests for these dosage forms are often run over a long time period. Accelerated in-vitro release methods can provide rapid evaluation and therefore are desirable for quality control purposes. To this end, different accelerated in-vitro release methods using United States Pharmacopeia (USP) apparatus have been developed. Different mechanisms of accelerating drug release from extended-release parenteral dosage forms, along with the accelerated in-vitro release testing methods currently employed are discussed. Accelerated in-vitro release testing methods with good discriminatory ability are critical for quality control of extended-release parenteral products. Methods that can be used in the development of in-vitro-in-vivo correlation (IVIVC) are desirable; however, for complex parenteral products this may not always be achievable. © 2012 The Authors. JPP © 2012 Royal Pharmaceutical Society.

  11. Accelerated in vitro release testing methods for extended release parenteral dosage forms

    Science.gov (United States)

    Shen, Jie; Burgess, Diane J.

    2012-01-01

    Objectives This review highlights current methods and strategies for accelerated in vitro drug release testing of extended release parenteral dosage forms such as polymeric microparticulate systems, lipid microparticulate systems, in situ depot-forming systems, and implants. Key findings Extended release parenteral dosage forms are typically designed to maintain the effective drug concentration over periods of weeks, months or even years. Consequently, “real-time” in vitro release tests for these dosage forms are often run over a long time period. Accelerated in vitro release methods can provide rapid evaluation and therefore are desirable for quality control purposes. To this end, different accelerated in vitro release methods using United States Pharmacopoeia (USP) apparatus have been developed. Different mechanisms of accelerating drug release from extended release parenteral dosage forms, along with the accelerated in vitro release testing methods currently employed are discussed. Conclusions Accelerated in vitro release testing methods with good discriminatory ability are critical for quality control of extended release parenteral products. Methods that can be used in the development of in vitro-in vivo correlation (IVIVC) are desirable, however for complex parenteral products this may not always be achievable. PMID:22686344

  12. Controlled-release oxycodone-induced seizures.

    Science.gov (United States)

    Klein, Moti; Rudich, Zvia; Gurevich, Boris; Lifshitz, Matityahu; Brill, Silviu; Lottan, Michael; Weksler, Natan

    2005-11-01

    The use of the opioid oxycodone hydrochloride in the management of chronic pain is gaining popularity principally because of its tolerability. However, opioid-related seizure in patients with epilepsy or other conditions that may decrease seizure threshold has been described in the literature; in particular, oxycodone has been associated with seizure in a patient with acute renal failure. The aim of this article was to report a patient with a history of seizures but normal renal and hepatic function who developed seizure on 2 occasions after oxycodone ingestion. A 54-year-old male patient presented with a history of tonic-clonic seizures that developed immediately after intracranial surgery. Long-term treatment with carbamazepine 400 mg QD was started, and the patient was free of convulsions for approximately 7 years. The patient presented to us with severe headache that was nonresponsive to an NSAID and the opiate agonist tramadol. Treatment with controlled-release (CR) oxycodone and tramadol drops (50 mg QID if necessary) was started, and tonic-clonic seizures developed 3 days later. Based on laboratory analysis, the patient had normal renal and hepatic function. On discontinuation of oxycodone treatment, the seizures resolved. However, due to effective pain relief with oxycodone, the patient decided to continue treatment, and seizures recurred. Carbamazepine was then administered 4 hours before oxycodone dosing, which allowed continuation of treatment without seizure. A patient with a history of seizures controlled with long-term carbamazepine therapy developed seizures when he started treatment with oxycodone CR at recommended doses. Oxycodone CR should be used with extreme caution in patients with epilepsy or other conditions that may decrease seizure threshold.

  13. Online identification algorithms for integrated dielectric electroactive polymer sensors and self-sensing concepts

    International Nuclear Information System (INIS)

    Hoffstadt, Thorben; Griese, Martin; Maas, Jürgen

    2014-01-01

    Transducers based on dielectric electroactive polymers (DEAP) use electrostatic pressure to convert electric energy into strain energy or vice versa. Besides this, they are also designed for sensor applications in monitoring the actual stretch state on the basis of the deformation dependent capacitive–resistive behavior of the DEAP. In order to enable an efficient and proper closed loop control operation of these transducers, e.g. in positioning or energy harvesting applications, on the one hand, sensors based on DEAP material can be integrated into the transducers and evaluated externally, and on the other hand, the transducer itself can be used as a sensor, also in terms of self-sensing. For this purpose the characteristic electrical behavior of the transducer has to be evaluated in order to determine the mechanical state. Also, adequate online identification algorithms with sufficient accuracy and dynamics are required, independent from the sensor concept utilized, in order to determine the electrical DEAP parameters in real time. Therefore, in this contribution, algorithms are developed in the frequency domain for identifications of the capacitance as well as the electrode and polymer resistance of a DEAP, which are validated by measurements. These algorithms are designed for self-sensing applications, especially if the power electronics utilized is operated at a constant switching frequency, and parasitic harmonic oscillations are induced besides the desired DC value. These oscillations can be used for the online identification, so an additional superimposed excitation is no longer necessary. For this purpose a dual active bridge (DAB) is introduced to drive the DEAP transducer. The capabilities of the real-time identification algorithm in combination with the DAB are presented in detail and discussed, finally. (paper)

  14. Controlled release of Pantoea agglomerans E325 for biocontrol of fire blight

    Science.gov (United States)

    Microencapsulation and controlled release of Pantoea agglomerans strain E325 (E325), which is an antagonist to bacterial pathogen (Erwinia amylovora) of fire blight, a devastating disease of apple and pear, have been investigated. Uniform core-shell alginate microcapsules (AMCs), 60-300 µm in diamet...

  15. Investigating the feasibility of temperature-controlled accelerated drug release testing for an intravaginal ring.

    Science.gov (United States)

    Externbrink, Anna; Clark, Meredith R; Friend, David R; Klein, Sandra

    2013-11-01

    The objective of the present study was to investigate if temperature can be utilized to accelerate drug release from Nuvaring®, a reservoir type intravaginal ring based on polyethylene vinyl acetate copolymer that releases a constant dose of contraceptive steroids over a duration of 3 weeks. The reciprocating holder apparatus (USP 7) was utilized to determine real-time and accelerated etonogestrel release from ring segments. It was demonstrated that drug release increased with increasing temperature which can be attributed to enhanced drug diffusion. An Arrhenius relationship of the zero-order release constants was established, indicating that temperature is a valid parameter to accelerate drug release from this dosage form and that the release mechanism is maintained under these accelerated test conditions. Accelerated release tests are particularly useful for routine quality control to assist during batch release of extended release formulations that typically release the active over several weeks, months or even years, since they can increase the product shelf life. The accelerated method should therefore be able to discriminate between formulations with different release characteristics that can result from normal manufacturing variance. In the case of Nuvaring®, it is well known that the process parameters during the extrusion process strongly influence the polymeric structure. These changes in the polymeric structure can affect the permeability which, in turn, is reflected in the release properties. Results from this study indicate that changes in the polymeric structure can lead to a different temperature dependence of the release rate, and as a consequence, the accelerated method can become less sensitive to detect changes in the release properties. When the accelerated method is utilized during batch release, it is therefore important to take this possible restriction into account and to evaluate the accelerated method with samples from non

  16. Halloysite Nanotubes: Controlled Access and Release by Smart Gates.

    Science.gov (United States)

    Cavallaro, Giuseppe; Danilushkina, Anna A; Evtugyn, Vladimir G; Lazzara, Giuseppe; Milioto, Stefana; Parisi, Filippo; Rozhina, Elvira V; Fakhrullin, Rawil F

    2017-07-28

    Hollow halloysite nanotubes have been used as nanocontainers for loading and for the triggered release of calcium hydroxide for paper preservation. A strategy for placing end-stoppers into the tubular nanocontainer is proposed and the sustained release from the cavity is reported. The incorporation of Ca(OH)₂ into the nanotube lumen, as demonstrated using transmission electron microscopy (TEM) imaging and Energy Dispersive X-ray (EDX) mapping, retards the carbonatation, delaying the reaction with CO₂ gas. This effect can be further controlled by placing the end-stoppers. The obtained material is tested for paper deacidification. We prove that adding halloysite filled with Ca(OH)₂ to paper can reduce the impact of acid exposure on both the mechanical performance and pH alteration. The end-stoppers have a double effect: they preserve the calcium hydroxide from carbonation, and they prevent from the formation of highly basic pH and trigger the response to acid exposure minimizing the pH drop-down. These features are promising for a composite nanoadditive in the smart protection of cellulose-based materials.

  17. Contact lenses as drug controlled release systems: a narrative review

    Directory of Open Access Journals (Sweden)

    Helena Prior Filipe

    2016-06-01

    Full Text Available ABSTRACT Topically applied therapy is the most common way to treat ocular diseases, however given the anatomical and physiological constraints of the eye, frequent dosing is required with possible repercussions in terms of patient compliance. Beyond refractive error correction, contact lenses (CLs have, in the last few decades emerged as a potential ophthalmic drug controlled release system (DCRS. Extensive research is underway to understand how to best modify CLs to increase residence time and bioavailability of drugs within therapeutic levels on the ocular surface.These devices may simultaneously correct ametropia and have a role in managing ophthalmic disorders that can hinder CL wear such as dry eye, glaucoma, ocular allergy and cornea infection and injury. In this narrative review the authors explain how the ocular surface structures determine drug diffusion in the eye and summarize the strategies to enhance drug residence time and bioavailability. They synthesize findings and clinical applications of drug soaked CLs as DCRS combined with delivery diffusion barriers, incorporation of functional monomers, ion related controlled release, molecular imprinting, nanoparticles and layering. The authors draw conclusions about the impact of these novel ophthalmic agents delivery systems in improving drug transport in the target tissue and patient compliance, in reducing systemic absorption and undesired side effects, and discuss future perspectives.

  18. A glassy carbon electrode modified with an amphiphilic, electroactive and photosensitive polymer and with multi-walled carbon nanotubes for simultaneous determination of dopamine and paracetamole

    International Nuclear Information System (INIS)

    Liu, Ren; Zeng, Xuebiao; Liu, Jingcheng; Luo, Jing; Zheng, Yuanyi; Liu, Xiaoya

    2016-01-01

    The article describes an electrochemical sensor for simultaneous determination of dopamine (DA) and paracetamole (PAT). It is based on the use of an electroactive polymer (referred to as BPVCM) to functionalize multi-walled carbon nanotubes. BPVCM is a branched amphiphilic photo-sensitive and electroactive polymer that was obtained by copolymerization of a vinyl benzyl carbazole, maleic acid anhydride, 4-vinyl benzylthiol and a vinylbenzyl oxycoumarin. BPVCM efficiently disperses MWCNT in aqueous solution. The electropolymerization of the carbazole moieties of the BPVCM enhances the current response. It also facilitates electron transfer in the MWCNT-BPVCM hybrid as evidenced by cyclic voltammetry and electrochemical impedance spectroscopy. A glassy carbon electrode modified with the nanocomposite displays outstanding electrocatalytic activity towards DA and PAT. DA can be determined, best at a working voltage of 0.2 V (vs. SCE), in the 5 to 1000 μM concentration range with a 2.3 μM detection limit. PAT can be determined in parallel, at a working voltage of 0.39 V (vs. SCE), in the same concentration range with a 3.5 μM detection limit. This analytical range of this method is wider than that of most alternative methods. (author)

  19. A Glutamate Homeostat Controls the Presynaptic Inhibition of Neurotransmitter Release

    Directory of Open Access Journals (Sweden)

    Xiling Li

    2018-05-01

    Full Text Available Summary: We have interrogated the synaptic dialog that enables the bi-directional, homeostatic control of presynaptic efficacy at the glutamatergic Drosophila neuromuscular junction (NMJ. We find that homeostatic depression and potentiation use disparate genetic, induction, and expression mechanisms. Specifically, homeostatic potentiation is achieved through reduced CaMKII activity postsynaptically and increased abundance of active zone material presynaptically at one of the two neuronal subtypes innervating the NMJ, while homeostatic depression occurs without alterations in CaMKII activity and is expressed at both neuronal subtypes. Furthermore, homeostatic depression is only induced through excess presynaptic glutamate release and operates with disregard to the postsynaptic response. We propose that two independent homeostats modulate presynaptic efficacy at the Drosophila NMJ: one is an intercellular signaling system that potentiates synaptic strength following diminished postsynaptic excitability, while the other adaptively modulates presynaptic glutamate release through an autocrine mechanism without feedback from the postsynaptic compartment. : Homeostatic mechanisms stabilize synaptic strength, but the signaling systems remain enigmatic. Li et al. suggest the existence of a homeostat operating at the Drosophila neuromuscular junction that responds to excess glutamate through an autocrine mechanism to adaptively inhibit presynaptic neurotransmitter release. This system parallels forms of plasticity at central synapses. Keywords: homeostatic synaptic plasticity, glutamate homeostasis, synaptic depression, Drosophila neuromuscular junction

  20. Formulation and Pharmacokinetic Evaluation of Controlled-Release ...

    African Journals Online (AJOL)

    A coating layer was then applied with a mixture of HPMC, ethylcellulose, shellac, and HPMC phthalate. The effect of several formulation variables on in vitro drug release was studied; furthermore, the drug release kinetics of the optimized formulation was evaluated. The in vivo pharmacokinetics of the optimized formulation ...

  1. The origin of fine structure in near-field scanning optical lithography of an electroactive polymer

    International Nuclear Information System (INIS)

    Cotton, Daniel V; Belcher, Warwick J; Dastoor, Paul C; Fell, Christopher J

    2008-01-01

    Near-field scanning optical lithography (NSOL) has been used to produce arbitrary structures of the electroactive polymer polyphenylenevinylene at sizes comparable to optical wavelengths, which are of interest for integrated optical devices. The structures are characterized using AFM and SEM and exhibit interesting fine structure. The characteristic size and shape of the lithographic features and their associated fine structure have been examined in the context of the electric field distribution at the near-field scanning optical microscope tip. In particular, the Bethe-Bouwkamp model for electric field distribution at an aperture has been used in combination with a recently developed model for precursor solubility dependence on UV energy dose to predict the characteristics of lithographic features produced by NSOL. The fine structure in the lithographic features is also investigated and explained. Suggestions for the further improvement of the technique are made.

  2. Controlled release from aspirin based linear biodegradable poly(anhydride esters) for anti-inflammatory activity.

    Science.gov (United States)

    Dasgupta, Queeny; Movva, Sahitya; Chatterjee, Kaushik; Madras, Giridhar

    2017-08-07

    This work reports the synthesis of a novel, aspirin-loaded, linear poly (anhydride ester) and provides mechanistic insights into the release of aspirin from this polymer for anti-inflammatory activity. As compared to conventional drug delivery systems that rely on diffusion based release, incorporation of bioactives in the polymer backbone is challenging and high loading is difficult to achieve. In the present study, we exploit the pentafunctional sugar alcohol (xylitol) to provide sites for drug (aspirin) attachment at its non-terminal OH groups. The terminal OH groups are polymerized with a diacid anhydride. The hydrolysis of the anhydride and ester bonds under physiological conditions release aspirin from the matrix. The resulting poly(anhydride ester) has high drug loading (53%) and displays controlled release kinetics of aspirin. The polymer releases 8.5 % and 20%, of the loaded drug in one and four weeks, respectively and has a release rate constant of 0.0035h -0.61 . The release rate is suitable for its use as an anti-inflammatory agent without being cytotoxic. The polymer exhibits good cytocompatibility and anti-inflammatory properties and may find applications as injectable or as an implantable bioactive material. The physical insights into the release mechanism can provide development of other drug loaded polymers. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Use of hydrophilic and hydrophobic polymers for the development of controlled release tizanidine matrix tablets

    Directory of Open Access Journals (Sweden)

    Tariq Ali

    2014-12-01

    Full Text Available The aim of the present study was to develop tizanidine controlled release matrix. Formulations were designed using central composite method with the help of design expert version 7.0 software. Avicel pH 101 in the range of 14-50% was used as a filler, while HPMC K4M and K100M in the range of 25-55%, Ethylcellulose 10 ST and 10FP in the range of 15 - 45% and Kollidon SR in the range of 25-60% were used as controlled release agents in designing different formulations. Various physical parameters including powder flow for blends and weight variation, thickness, hardness, friability, disintegration time and in-vitro release were tested for tablets. Assay of tablets were also performed as specified in USP 35 NF 32. Physical parameters of both powder blend and compressed tablets such as compressibility index, angle of repose, weight variation, thickness, hardness, friability, disintegration time and assay were evaluated and found to be satisfactory for formulations K4M2, K4M3, K4M9, K100M2, K100M3, K100M9, E10FP2, E10FP9, KSR2, KSR3 & KSR9. In vitro dissolution study was conducted in 900 ml of 0.1N HCl, phosphate buffer pH 4.5 and 6.8 medium using USP Apparatus II. In vitro release profiles indicated that formulations prepared with Ethocel 10 standard were unable to control the release of drug while formulations K4M2, K100M9, E10FP2 & KSR2 having polymer content ranging from 40-55% showed a controlled drug release pattern in the above mentioned medium. Zero-order drug release kinetics was observed for formulations K4M2, K100M9, E10FP2 & KSR2. Similarity test (f2 results for K4M2, E10FP2 & KSR2 were found to be comparable with reference formulation K100M9. Response Surface plots were also prepared for evaluating the effect of independent variable on the responses. Stability study was performed as per ICH guidelines and the calculated shelf life was 24-30 months for formulation K4M2, K100M9 and E10FP2.

  4. Thermal treating of acrylic matrices as a tool for controlling drug release.

    Science.gov (United States)

    Hasanzadeh, Davood; Ghaffari, Solmaz; Monajjemzadeh, Farnaz; Al-Hallak, M H D-Kamal; Soltani, Ghazal; Azarmi, Shirzad

    2009-12-01

    The purpose of the present study was to investigate the effect of thermal-treating on the release of ibuprofen from the granules prepared using aqueous dispersions of Eudragit. To accomplish this goal, different formulations were prepared using wet granulation method containing two different types of Eudragit aqueous dispersions, RS30D, RL30D and Avicel as filler. Tablets were prepared using direct compression method. The prepared tablets were thermally treated at 50 and 70 degrees C for 24 h. The drug release from tablets was assessed before and after thermal-treating. The results of release study showed that, thermally-treating the tablets at the temperatures higher than glass transition temperature (Tg) of the polymer can decrease the drug release from matrices. For mechanistic evaluation of the effect of thermal-treating, powder X-ray diffraction (XPD), scanning electron microscopy (SEM), differential scanning calorimeter (DSC), Fourier transform infrared (FT-IR) and helium pycnometer have been employed. The SEM graphs showed that the tablets have smoother surface with less porosity after thermal-treating. FT-IR spectra showed no change in the spectrum of thermally-treated tablet compared to control. In DSC graphs, no crystalline change was seen in the heat-treated samples of ibuprofen tablets, but decreased and widened peak size were related to the probable formation of solid solution of ibuprofen in Eudragit matrix. The results of helium pycnometer showed a significant decrease in the total porosity of some heat-treated samples. This study revealed the importance of thermal treating on the drug release from sustained release tablets containing Eudragit polymer.

  5. Combined gelatin-chondroitin sulfate hydrogels for controlled release of cationic antibacterial proteins

    NARCIS (Netherlands)

    Kuijpers, A. J.; Engbers, G. H. M.; Meyvis, T. K. L.; de Smedt, S. S. C.; Demeester, J.; Krijgsveld, J.; Zaat, S. A. J.; Dankert, J.; Feijen, J.

    2000-01-01

    Chemically cross-linked gelatin-chondroitin sulfate (ChS) hydrogels were prepared for the controlled release of small cationic proteins. The amount of chondroitin sulfate in the gelatin gels varied between 0 and 20 wt %. The chemical cross-link density, the degree of swelling, and the rheological

  6. The comparison between limited open carpal tunnel release using direct vision and tunneling technique and standard open carpal tunnel release: a randomized controlled trial study.

    Science.gov (United States)

    Suppaphol, Sorasak; Worathanarat, Patarawan; Kawinwongkovit, Viroj; Pittayawutwinit, Preecha

    2012-04-01

    To compare the operative outcome of carpal tunnel release between limited open carpal tunnel release using direct vision and tunneling technique (group A) with standard open carpal tunnel release (group B). Twenty-eight patients were enrolled in the present study. A single blind randomized control trial study was conducted to compare the postoperative results between group A and B. The study parameters were Levine's symptom severity and functional score, grip and pinch strength, and average two-point discrimination. The postoperative results between two groups were comparable with no statistical significance. Only grip strength at three months follow up was significantly greater in group A than in group B. The limited open carpal tunnel release in the present study is effective comparable to the standard open carpal tunnel release. The others advantage of this technique are better cosmesis and improvement in grip strength at the three months postoperative period.

  7. Competitive interactions and controlled release of a natural antioxidant from halloysite nanotubes.

    Science.gov (United States)

    Hári, József; Gyürki, Ádám; Sárközi, Márk; Földes, Enikő; Pukánszky, Béla

    2016-01-15

    Halloysite nanotubes used as potential carrier material for a controlled release stabilizer in polyethylene were thoroughly characterized with several techniques including the measurement of specific surface area, pore volume and surface energy. The high surface energy of the halloysite results in the strong bonding of the additive to the surface. Dissolution experiments carried out with eight different solvents for the determination of the effect of solvent characteristics on the amount of irreversibly bonded quercetin proved that adsorption and dissolution depend on competitive interactions prevailing in the system. Solvents with low polarity dissolve only surplus quercetin adsorbed in multilayers. Polyethylene is a very apolar polymer forming weak interactions with every substance; quercetin dissolves into it from the halloysite surface only above a critical surface coverage. Stabilization experiments confirmed that strong adhesion prevents dissolution and results in limited stabilization efficiency. At larger adsorbed amounts better stability and extended effect were measured indicating dissolution and controlled release. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Enhanced electroactive and mechanical properties of poly(vinylidene fluoride) by controlling crystallization and interfacial interactions with low loading polydopamine coated BaTiO₃.

    Science.gov (United States)

    Jia, Nan; Xing, Qian; Liu, Xu; Sun, Jing; Xia, Guangmei; Huang, Wei; Song, Rui

    2015-09-01

    Poly(vinylidene fluoride) (PVDF) is a semi-crystalline polymer and the polar β-phase of PVDF shows superb electroactive properties. In order to enhance the β-phase of PVDF, extreme low content of BaTiO3 nanoparticles (BT-NPs) coated with polydopamine (Pdop) were incorporated into PVDF matrix by solution casting. The β-phase of the resulting PVDF nanocomposites film was dramatically increased and the d33 value reached 34.3±0.4 pCN(-1). It is found that the Pdop layer could improve the dispersibility and stability of the BT NPs in solution and endow the BT NPs good dispersity in the PVDF matrix. Moreover, the interfacial interaction between PVDF chains and the surface of BT-Pdop nanoparticles (BT-Pdop NPs) were revealed, in which the CF2 groups on PVDF could interact with the electron-rich plane of aromatic ring of Pdop moiety. This interaction, led to the increase of the crystallization activation energy as derived from the DSC nonisothermal crystallization measurement. The α-β crystal transformation, organization of interfacial interactions as well as the prevention of agglomeration of BT-NPs confer the improvement of mechanical and thermal properties of PVDF, such as toughness, tensile strength, elongation at break, and thermal conductivity. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Unexpected consequences of control: competitive vs. predator release in a four-species assemblage of invasive mammals.

    Science.gov (United States)

    Ruscoe, Wendy A; Ramsey, David S L; Pech, Roger P; Sweetapple, Peter J; Yockney, Ivor; Barron, Mandy C; Perry, Mike; Nugent, Graham; Carran, Roger; Warne, Rodney; Brausch, Chris; Duncan, Richard P

    2011-10-01

    Invasive species are frequently the target of eradication or control programmes to mitigate their impacts. However, manipulating single species in isolation can lead to unexpected consequences for other species, with outcomes such as mesopredator release demonstrated both theoretically and empirically in vertebrate assemblages with at least two trophic levels. Less is known about the consequences of species removal in more complex assemblages where a greater number of interacting invaders increases the potential for selective species removal to result in unexpected changes in community structure. Using a replicated Before-After Control-Impact field experiment with a four-species assemblage of invasive mammals we show that species interactions in the community are dominated by competition rather than predation. There was no measurable response of two mesopredators (rats and mice) following control of the top predator (stoats), but there was competitive release of rats following removal of a herbivore (possums), and competitive release of mice following removal of rats. © 2011 Blackwell Publishing Ltd/CNRS.

  10. STUDIES ON NATURAL AND SYNTHETIC POLYMERS FOR CONTROLLED RELEASE MATRIX TABLET OF ACECLOFENAC

    OpenAIRE

    Abhishek S. Joshi *, Deepak A. Joshi , Avinash V. Dhobale , Sandhya S. Bundel , Vijay R. Chakote, Gunesh N. Dhembre

    2018-01-01

    The present study was aimed to design new oral controlled release matrix tablets of new NSAID Aceclofenac for once a day by using 10, 15, 20 and 25% of GG:HPMC and XG:HPMC mixture in the ratio 1:1 by wet granulation method. The prepared tablets subjected to in vitro drug release studies in pH 7.4 buffer solution. All the formulation meets the pre-compression and compression characteristics. All the tablets prepared with 10, 15, 20 and 25% of HPMC: XG mixture in the ratio 1:1 fails to meet the...

  11. Novel HPLC Analysis of Hydrocortisone in Conventional and Controlled-Release Pharmaceutical Preparations

    Directory of Open Access Journals (Sweden)

    Ofosua Adi-Dako

    2017-01-01

    Full Text Available An isocratic sensitive and precise reverse phase high-performance liquid chromatography (RP-HPLC method was developed and validated for the determination and quantification of hydrocortisone in controlled-release and conventional (tablets and injections pharmaceutical preparations. Chromatographic separation was achieved on an ODS (C18, 5 μm, 4.6 × 150 mm, with an isocratic elution using a freshly prepared mobile phase of composition methanol : water : acetic acid (60 : 30 : 10, v/v/v at a flow rate of 1.0 ml/min. The detection of the drug was successfully achieved at a wavelength of 254 nm. The retention time obtained for the drug was 2.26 min. The proposed method produced linear detectable responses in the concentration range of 0.02 to 0.4 mg/ml of hydrocortisone. High recoveries of 98–101% were attained at concentration levels of 80%, 100%, and 120%. The intraday and interday precision (RSD were 0.19–0.55% and 0.33–0.71%, respectively. A comparison of hydrocortisone analyses data from the developed method and the official USP method showed no significant difference (p>0.05 at a 95% confidence interval. The method was successfully applied to the determination and quantification of hydrocortisone in six controlled-release and fifteen conventional release pharmaceutical preparations.

  12. Composite microsphere-functionalized scaffold for the controlled release of small molecules in tissue engineering

    Directory of Open Access Journals (Sweden)

    Laura Pandolfi

    2016-01-01

    Full Text Available Current tissue engineering strategies focus on restoring damaged tissue architectures using biologically active scaffolds. The ideal scaffold would mimic the extracellular matrix of any tissue of interest, promoting cell proliferation and de novo extracellular matrix deposition. A plethora of techniques have been evaluated to engineer scaffolds for the controlled and targeted release of bioactive molecules to provide a functional structure for tissue growth and remodeling, as well as enhance recruitment and proliferation of autologous cells within the implant. Recently, novel approaches using small molecules, instead of growth factors, have been exploited to regulate tissue regeneration. The use of small synthetic molecules could be very advantageous because of their stability, tunability, and low cost. Herein, we propose a chitosan–gelatin scaffold functionalized with composite microspheres consisting of mesoporous silicon microparticles and poly(dl-lactic-co-glycolic acid for the controlled release of sphingosine-1-phospate, a small molecule of interest. We characterized the platform with scanning electron microscopy, Fourier transform infrared spectroscopy, and confocal microscopy. Finally, the biocompatibility of this multiscale system was analyzed by culturing human mesenchymal stem cells onto the scaffold. The presented strategy establishes the basis of a versatile scaffold for the controlled release of small molecules and for culturing mesenchymal stem cells for regenerative medicine applications.

  13. Development and evaluation of diltiazem hydrochloride controlled-release pellets by fluid bed coating process

    Directory of Open Access Journals (Sweden)

    Mikkilineni Bhanu Prasad

    2013-01-01

    Full Text Available The aim of the present study was to develop controlled-release pellets of diltiazem HCl with ethyl cellulose and hydroxylpropyl methylcellulose phthalate as the release rate retarding polymers by fluid bed coating technique. The prepared pellets were evaluated for drug content, particle size, subjected to Scanning Electron Microscopy (SEM and Differential Scanning Calori metry (DSC, and evaluated for in vitro release. Stability studies were carried out on the optimized formulations for a period of 3 months. The drug content was in the range of 97%-101%. The mean particle size of the drug-loaded pellets was in the range 700-785 μm. The drug release rate decreased as the concentration of ethyl cellulose increased in the pellet formulations. Among the prepared formulations, FDL10 and FDL11 showed 80% drug release in 16 h, matching with USP dissolution test 6 for diltiazem HCl extended-release capsules. SEM photographs confirmed that the prepared formulations were spherical in nature with a smooth surface. The compatibility between drug and polymers in the drug-loaded pellets was confirmed by DSC studies. Stability studies indicated that the pellets were stable.

  14. pH-Sensitive Amphiphilic Block-Copolymers for Transport and Controlled Release of Oxygen

    KAUST Repository

    Patil, Yogesh Raghunath

    2017-05-31

    Saturated fluorocarbons, their derivatives and emulsions are capable of dissolving anomalously high amounts of oxygen and other gases. The mechanistic aspects of this remarkable effect remain to be explored experimentally. Here, the synthesis of a library of amphiphilic fluorous block-copolymers incorporating different fluorinated monomers is described, and the capacity of these copolymers for oxygen transport in water is systematically investigated. The structure of the fluorous monomer employed was found to have a profound effect on both the oxygen-carrying capacity and the gas release kinetics of the polymer emulsions. Furthermore, the release of O2 from the polymer dispersions could be triggered by changing the pH of the solution. This is the first example of a polymer-based system for controlled release of a non-polar, non-covalently entrapped respiratory gas.

  15. pH-Sensitive Amphiphilic Block-Copolymers for Transport and Controlled Release of Oxygen

    KAUST Repository

    Patil, Yogesh Raghunath; Almahdali, Sarah; Vu, Khanh B.; Zapsas, Georgios; Hadjichristidis, Nikolaos; Rodionov, Valentin

    2017-01-01

    Saturated fluorocarbons, their derivatives and emulsions are capable of dissolving anomalously high amounts of oxygen and other gases. The mechanistic aspects of this remarkable effect remain to be explored experimentally. Here, the synthesis of a library of amphiphilic fluorous block-copolymers incorporating different fluorinated monomers is described, and the capacity of these copolymers for oxygen transport in water is systematically investigated. The structure of the fluorous monomer employed was found to have a profound effect on both the oxygen-carrying capacity and the gas release kinetics of the polymer emulsions. Furthermore, the release of O2 from the polymer dispersions could be triggered by changing the pH of the solution. This is the first example of a polymer-based system for controlled release of a non-polar, non-covalently entrapped respiratory gas.

  16. Newton Output Blocking Force under Low-Voltage Stimulation for Carbon Nanotube-Electroactive Polymer Composite Artificial Muscles.

    Science.gov (United States)

    Chen, I-Wen Peter; Yang, Ming-Chia; Yang, Chia-Hui; Zhong, Dai-Xuan; Hsu, Ming-Chun; Chen, YiWen

    2017-02-15

    This is a study on the development of carbon nanotube-based composite actuators using a new ionic liquid-doped electroactive ionic polymer. For scalable production purposes, a simple hot-pressing method was used. Carbon nanotube/ionic liquid-Nafion/carbon nanotube composite films were fabricated that exhibited a large output blocking force and a stable cycling life with low alternating voltage stimuli in air. Of particular interest and importance, a blocking force of 1.5 N was achieved at an applied voltage of 6 V. Operational durability was confirmed by testing in air for over 30 000 cycles (or 43 h). The superior actuation performance of the carbon nanotube/ionic liquid-Nafion/carbon nanotube composite, coupled with easy manufacturability, low driving voltage, and reliable operation, promises great potential for artificial muscle and biomimetic applications.

  17. Electrically aligned cellulose film for electro-active paper and its piezoelectricity

    International Nuclear Information System (INIS)

    Yun, Sungryul; Jang, Sangdong; Yun, Gyu-Young; Kim, Jaehwan

    2009-01-01

    Electrically aligned regenerated cellulose films were fabricated and the effect of applied electric field was investigated for the piezoelectricity of electro-active paper (EAPap). The EAPap was fabricated by coating gold electrodes on both sides of regenerated cellulose film. The cellulose film was prepared by dissolving cotton pulp in LiCl/N,N-dimethylacetamide solution followed by a cellulose chain regeneration process. During the regeneration process an external electric field was applied in the direction of mechanical stretching. Alignment of cellulose fiber chains was investigated as a function of applied electric field. The material characteristics of the cellulose films were analyzed by using an x-ray diffractometer, a field emission scanning electron microscope and a high voltage electron microscope. The application of external electric fields was found to induce formation of nanofibers in the cellulose, resulting in an increase in the crystallinity index (CI) values. It was also found that samples with higher CI values showed higher in-plane piezoelectric constant, d 31 , values. The piezoelectricity of the current EAPap films was measured to be equivalent or better than that of ordinary PVDF films. Therefore, an external electric field applied to a cellulose film along with a mechanical stretching during the regeneration process can enhance the piezoelectricity. (technical note)

  18. Characterization and electromechanical performance of cellulose–chitosan blend electro-active paper

    International Nuclear Information System (INIS)

    Cai Zhijiang; Kim, Jaehwan

    2008-01-01

    Cellulose-based electro-active paper (EAPap) has been reported as a smart material that has merits in terms of light weight, dry condition, biodegradability, sustainability, large displacement output and low actuation voltage. However, its actuator performance is very sensitive to humidity and degrades with time. To solve these drawbacks, we introduce an EAPap actuator made with cellulose and chitosan blend films. Cellulose–chitosan blend films were prepared by dissolving the polymers in trifluoroacetic acid as a co-solvent followed by spin-coating onto glass substrates. A bending EAPap actuator is made by depositing thin gold electrodes on both sides of the cellulose–chitosan films. Characteristics of these blend films are performed by FT-IR, XRD, TGA, SEM and a pull test. The electromechanical performance of the EAPap actuator is evaluated in terms of free bending displacement with respect to the actuation frequency, voltage, time variation and humidity levels. Results show that this chitosan–cellulose-based EAPap actuator is less sensitive to humidity: it shows a large bending displacement (about 4.1 mm) and long lifetime (more than 9 h) at room humidity conditions. It indicates that this chitosan–cellulose EAPap is promising for many biomimetic applications in the foreseeable future

  19. Biomimetic synthesized chiral mesoporous silica: Structures and controlled release functions as drug carrier

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jing; Xu, Lu, E-mail: xl2013109@163.com; Yang, Baixue; Bao, Zhihong; Pan, Weisan; Li, Sanming, E-mail: li_sanming2013@163.com

    2015-10-01

    This work initially illustrated the formation mechanism of chiral mesoporous silica (CMS) in a brand new insight named biomimetic synthesis. Three kinds of biomimetic synthesized CMS (B-CMS, including B-CMS1, B-CMS2 and B-CMS3) were prepared using different pH or stirring rate condition, and their characteristics were tested with transmission electron microscope and small angle X-ray diffraction. The model drug indomethacin was loaded into B-CMS and drug loading content was measured using ultraviolet spectroscopy. The result suggested that pH condition influenced energetics of self-assembly process, mainly packing energetics of the surfactant, while stirring rate was the more dominant factor to determine particle length. In application, indomethacin loading content was measured to be 35.3%, 34.8% and 35.1% for indomethacin loaded B-CMS1, indomethacin loaded B-CMS2 and indomethacin loaded B-CMS3. After loading indomethacin into B-CMS carriers, surface area, pore volume and pore diameter of B-CMS carriers were reduced. B-CMS converted crystalline state of indomethacin to amorphous state, leading to the improved indomethacin dissolution. B-CMS1 controlled drug release without burst-release, while B-CMS2 and B-CMS3 released indomethacin faster than B-CMS1, demonstrating that the particle length, the ordered lever of multiple helixes, the curvature degree of helical channels and pore diameter greatly contributed to the release behavior of indomethacin loaded B-CMS. - Highlights: • Chiral mesoporous silica was synthesized using biomimetic method. • pH influenced energetics of self-assembly process of chiral mesoporous silica. • Stirring rate determined the particle length of chiral mesoporous silica. • Controlled release behaviors of chiral mesoporous silica varied based on structures.

  20. Biomimetic synthesized chiral mesoporous silica: Structures and controlled release functions as drug carrier

    International Nuclear Information System (INIS)

    Li, Jing; Xu, Lu; Yang, Baixue; Bao, Zhihong; Pan, Weisan; Li, Sanming

    2015-01-01

    This work initially illustrated the formation mechanism of chiral mesoporous silica (CMS) in a brand new insight named biomimetic synthesis. Three kinds of biomimetic synthesized CMS (B-CMS, including B-CMS1, B-CMS2 and B-CMS3) were prepared using different pH or stirring rate condition, and their characteristics were tested with transmission electron microscope and small angle X-ray diffraction. The model drug indomethacin was loaded into B-CMS and drug loading content was measured using ultraviolet spectroscopy. The result suggested that pH condition influenced energetics of self-assembly process, mainly packing energetics of the surfactant, while stirring rate was the more dominant factor to determine particle length. In application, indomethacin loading content was measured to be 35.3%, 34.8% and 35.1% for indomethacin loaded B-CMS1, indomethacin loaded B-CMS2 and indomethacin loaded B-CMS3. After loading indomethacin into B-CMS carriers, surface area, pore volume and pore diameter of B-CMS carriers were reduced. B-CMS converted crystalline state of indomethacin to amorphous state, leading to the improved indomethacin dissolution. B-CMS1 controlled drug release without burst-release, while B-CMS2 and B-CMS3 released indomethacin faster than B-CMS1, demonstrating that the particle length, the ordered lever of multiple helixes, the curvature degree of helical channels and pore diameter greatly contributed to the release behavior of indomethacin loaded B-CMS. - Highlights: • Chiral mesoporous silica was synthesized using biomimetic method. • pH influenced energetics of self-assembly process of chiral mesoporous silica. • Stirring rate determined the particle length of chiral mesoporous silica. • Controlled release behaviors of chiral mesoporous silica varied based on structures

  1. The preparation, characterization and actuation behavior of polyaniline and cellulose blended electro-active paper

    International Nuclear Information System (INIS)

    John, Amalraj; Mahadeva, Suresha K; Kim, Jaehwan

    2010-01-01

    This paper reports polyaniline and cellulose blended electro-active paper (EAPap) that can produce large bending displacement at ambient humidity conditions with long lifetime durability. A novel solution processable polyaniline-p-toluene sulfonate (PANI–PTSA) salt was prepared by an inverted emulsion polymerization technique using benzoyl peroxide and p-toluene sulfonic acid. Cellulose solution prepared by dissolving cotton with lithium chloride/N, N-dimethylacetamide was mixed with the PANI emaraldine salt solution and a cellulose–PANI blended film was obtained. The obtained cellulose–PANI film was characterized by ultraviolet–visible (UV–visible), x-ray diffraction, scanning electron microscopy and tensile test methods. A cellulose–PANI EAPap actuator was made by depositing very thin gold electrodes on both sides of the cellulose–PANI film. When the actuator performance of the cellulose–PANI EAPap was evaluated in terms of bending displacement with respect to the actuation frequencies, voltages and relative humidity levels, a large bending displacement was shown at ambient humidity conditions with long lifetime durability

  2. Triggered Release from Polymer Capsules

    Energy Technology Data Exchange (ETDEWEB)

    Esser-Kahn, Aaron P. [Univ. of Illinois, Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology and Dept. of Chemistry; Odom, Susan A. [Univ. of Illinois, Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology and Dept. of Chemistry; Sottos, Nancy R. [Univ. of Illinois, Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology and Dept. of Materials Science and Engineering; White, Scott R. [Univ. of Illinois, Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology and Dept. of Aerospace Engineering; Moore, Jeffrey S. [Univ. of Illinois, Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology and Dept. of Chemistry

    2011-07-06

    Stimuli-responsive capsules are of interest in drug delivery, fragrance release, food preservation, and self-healing materials. Many methods are used to trigger the release of encapsulated contents. Here we highlight mechanisms for the controlled release of encapsulated cargo that utilize chemical reactions occurring in solid polymeric shell walls. Triggering mechanisms responsible for covalent bond cleavage that result in the release of capsule contents include chemical, biological, light, thermal, magnetic, and electrical stimuli. We present methods for encapsulation and release, triggering methods, and mechanisms and conclude with our opinions on interesting obstacles for chemically induced activation with relevance for controlled release.

  3. Utilization of wheat straw for the preparation of coated controlled-release fertilizer with the function of water retention.

    Science.gov (United States)

    Xie, Lihua; Liu, Mingzhu; Ni, Boli; Wang, Yanfang

    2012-07-18

    With the aim of improving fertilizer use efficiency and minimizing the negative impact on the environment, a new coated controlled-release fertilizer with the function of water retention was prepared. A novel low water solubility macromolecular fertilizer, poly(dimethylourea phosphate) (PDUP), was "designed" and formulated from N,N'-dimethylolurea (DMU) and potassium dihydrogen phosphate. Simultaneously, an eco-friendly superabsorbent composite based on wheat straw (WS), acrylic acid (AA), 2-acryloylamino-2-methyl-1-propanesulfonic acid (AMPS), and N-hydroxymethyl acrylamide (NHMAAm) was synthesized and used as the coating to control the release of nutrient. The nitrogen release profile and water retention capacity of the product were also investigated. The degradation of the coating material in soil solution was studied. Meanwhile, the impact of the content of N-hydroxymethyl acrylamide on the degradation extent was examined. The experimental data showed that the product with good water retention and controlled-release capacities, being economical and eco-friendly, could be promising for applications in agriculture and horticulture.

  4. Montmorillonite/Poly (L-Lactide microcomposite spheres as reservoirs of antidepressant drugs and their controlled release property

    Directory of Open Access Journals (Sweden)

    Shalini Rajkumar

    2015-10-01

    Full Text Available This work evaluates intercalation of Nortriptyline (NT and Venlafaxine (VFX in an interlayer gallery of Na+-MMT (Montmorillonite, which was further compounded with Poly (L-Lactide (PLLA to form microcomposite spheres (MPs for oral controlled drug delivery. The XRD patterns, thermal and spectroscopic analyses indicated intercalation of drugs into the MMT interlayer that was stabilized by electrostatic interaction. No significant changes in structural and functional properties of drugs were found in the MMT layers. In vitro drug release studies showed controlled release pattern.

  5. Electroactive mesoporous yttria stabilized zirconia containing platinum or nickel oxide nanoclusters: a new class of solid oxide fuel cell electrode materials

    Energy Technology Data Exchange (ETDEWEB)

    Mamak, M.; Coombs, N.; Ozin, G.A. [Toronto Univ., ON (Canada). Dept. of Chemistry

    2001-02-01

    The electroactivity of surfactant-templated mesoporous yttria stabilized zirconia, containing nanoclusters of platinum or nickel oxide, is explored by alternating current (AC) complex impedance spectroscopy. The observed oxygen ion and mixed oxygen ion-electron charge-transport behavior for these materials, compared to the sintered-densified non-porous crystalline versions, is ascribed to the unique integration of mesoporosity and nanocrystallinity within the binary and ternary solid solution microstructure. These attributes inspire interest in this new class of materials as candidates for the development of improved performance solid oxide fuel cell electrodes. (orig.)

  6. Graphene oxide directed in-situ deposition of electroactive silver nanoparticles and its electrochemical sensing application for DNA analysis

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Ningning [College of Chemistry and Environment, Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou, 363000 (China); Gao, Feng, E-mail: fgao1981@mnnu.edu.cn [College of Chemistry and Environment, Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou, 363000 (China); Department of Chemistry, Graduate School of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504 (Japan); He, Suyu; Zhu, Qionghua; Huang, Jiafu [College of Chemistry and Environment, Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou, 363000 (China); Tanaka, Hidekazu [Department of Chemistry, Graduate School of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504 (Japan); Wang, Qingxiang, E-mail: axiang236@126.com [College of Chemistry and Environment, Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou, 363000 (China)

    2017-01-25

    The development of high-performance biosensing platform is heavily dependent on the recognition property of the sensing layer and the output intensity of the signal probe. Herein, we present a simple and highly sensitive biosensing interface for DNA detection on the basis of graphene oxide nanosheets (GONs) directed in-situ deposition of silver nanoparticles (AgNPs). The fabrication process and electrochemical properties of the biosensing interface were probed by electrochemical techniques and scanning electron microscopy. The results indicate that GONs can specifically adsorb at the single-stranded DNA probe surface, and induces the deposition of highly electroactive AgNPs. Upon hybridization with complementary oligonucleotides to generate the duplex DNA on the electrode surface, the GONs with the deposited AgNPs will be liberated from the sensing interface due to the inferior affinity of GONs and duplex DNA, resulting in the reduction of the electrochemical signal. Such a strategy combines the superior recognition of GONs toward single-stranded DNA and double-stranded DNA, and the strong electrochemical response of in-situ deposited AgNPs. Under optimal conditions, the biosensor can detect target DNA over a wide range from 10 fM to 10 nM with a detection limit of 7.6 fM. Also, the developed biosensor shows outstanding discriminating ability toward oligonucleotides with different mismatching degrees. - Highlights: • An novel DNA biosensor was constructed based on GONs with deposited AgNPs. • GONs catalyze the in-situ deposition of AgNPs on the sensing interface. • Unique π-stacking of GONs with probe DNA contributes high selectivity of the biosensor. • High electroactivity of AgNPs leads to low detection limit (7.6 fM) for target DNA.

  7. Requirements for controlling a repository's releases of carbon-14 dioxide; the high costs and negligible benefits

    International Nuclear Information System (INIS)

    Park, U Sun; Pflum, C.G.

    1990-01-01

    A repository excavated within the unsaturated zone may release carbon (C)-14 dioxide in amounts that exceed limits imposed by the Environmental Protection Agency (EPA) and the Nuclear Regulatory Commission (NRC). The release would not threaten the general population, but may expose some hypothetical maximally exposed individual to 0.0005 millirems/year. Yet a repository's releases of C-14 dioxide are strictly regulated, perhaps unintentionally. The EPA and NRC regulations could force the Department of Energy to design and fabricate an expensive 10,000-year waste package solely for the sake of controlling releases of C-14 dioxide. This paper argues that the repository regulations should exempt releases of C-14 dioxide or at least impose more equitable limits. 21 refs., 1 tab

  8. [Research on controlling iron release of desalted water transmitted in existing water distribution system].

    Science.gov (United States)

    Tian, Yi-Mei; Liu, Yang; Zhao, Peng; Shan, Jin-Lin; Yang, Suo-Yin; Liu, Wei

    2012-04-01

    Desalted water, with strong corrosion characteristics, would possibly lead to serious "red water" when transmitted and distributed in existing municipal water distribution network. The main reason for red water phenomenon is iron release in water pipes. In order to study the methods of controlling iron release in existing drinking water distribution pipe, tubercle analysis of steel pipe and cast iron pipe, which have served the distribution system for 30-40 years, was carried out, the main construction materials were Fe3O4 and FeOOH; and immersion experiments were carried in more corrosive pipes. Through changing mixing volume of tap water and desalted water, pH, alkalinity, chloride and sulfate, the influence of different water quality indexes on iron release were mainly analyzed. Meanwhile, based on controlling iron content, water quality conditions were established to meet with the safety distribution of desalted water: volume ratio of potable water and desalted water should be higher than or equal to 2, pH was higher than 7.6, alkalinity was higher than 200 mg x L(-1).

  9. Potential for control of Cadra cautella (Walker) by release of fully or partially sterile males

    International Nuclear Information System (INIS)

    Brower, J.H.; Tilton, E.W.

    1975-01-01

    Modifications of the sterile-male release technique appear to offer promise for the control of post-harvest lepidopteran pest populations within storage structures. Theoretical models of release strategies for Cadra cautella showed that each method has an 'ideal' flooding ratio. This ratio represents the best balance between extinction in a few generations and minimization of the total number of insects released. From data reported concerning the population dynamics of Cadra cautella in the field an ideal flooding ratio for fully sterile (S) males to fertile (F) males of 97:1 would achieve extinction in 3 generations. Total numbers of males released per 100 native insects that would be needed to achieve extinction at these flooding ratios would be 14,850, 14,900 and 18,500, respectively. (author)

  10. HPMA copolymer-drug conjugates with controlled tumor-specific drug release

    Czech Academy of Sciences Publication Activity Database

    Chytil, Petr; Koziolová, Eva; Etrych, Tomáš; Ulbrich, Karel

    2018-01-01

    Roč. 18, č. 1 (2018), s. 1-15, č. článku 1700209. ISSN 1616-5187 R&D Projects: GA ČR(CZ) GA15-02986S; GA ČR(CZ) GA17-13283S; GA ČR(CZ) GA17-08084S; GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : biodegradable spacer * controlled drug release * drug delivery systems Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 3.238, year: 2016

  11. Electrically controlled drug release from nanostructured polypyrrole coated on titanium

    International Nuclear Information System (INIS)

    Sirivisoot, Sirinrath; Pareta, Rajesh; Webster, Thomas J

    2011-01-01

    Previous studies have demonstrated that multi-walled carbon nanotubes grown out of anodized nanotubular titanium (MWNT-Ti) can be used as a sensing electrode for various biomedical applications; such sensors detected the redox reactions of certain molecules, specifically proteins deposited by osteoblasts during extracellular matrix bone formation. Since it is known that polypyrrole (PPy) can release drugs upon electrical stimulation, in this study antibiotics (penicillin/streptomycin, P/S) or an anti-inflammatory drug (dexamethasone, Dex), termed PPy[P/S] or PPy[Dex], respectively, were electrodeposited in PPy on titanium. The objective of the present study was to determine if such drugs can be released from PPy on demand and (by applying a voltage) control cellular behavior important for orthopedic applications. Results showed that PPy films possessed nanometer-scale roughness as analyzed by atomic force microscopy. X-ray photoelectron spectroscopy confirmed the presence of P/S and Dex encapsulated within the PPy films. Results from cyclic voltammetry showed that 80% of the drugs were released on demand when sweep voltages were applied for five cycles at a scan rate of 0.1 V s -1 . Furthermore, osteoblast (bone-forming cells) and fibroblast (fibrous tissue-forming cells) adhesion were determined on the PPy films. Results showed that PPy[Dex] enhanced osteoblast adhesion after 4 h of culture compared to plain Ti. PPy-Ti (with or without anionic drug doping) inhibited fibroblast adhesion compared to plain Ti. These in vitro results confirmed that electrodeposited PPy[P/S] and PPy[Dex] can release drugs on demand to potentially fight bacterial infection, reduce inflammation, promote bone growth or reduce fibroblast functions, further implicating the use of such materials as implant sensors.

  12. Electrically controlled drug release from nanostructured polypyrrole coated on titanium

    Science.gov (United States)

    Sirivisoot, Sirinrath; Pareta, Rajesh; Webster, Thomas J.

    2011-02-01

    Previous studies have demonstrated that multi-walled carbon nanotubes grown out of anodized nanotubular titanium (MWNT-Ti) can be used as a sensing electrode for various biomedical applications; such sensors detected the redox reactions of certain molecules, specifically proteins deposited by osteoblasts during extracellular matrix bone formation. Since it is known that polypyrrole (PPy) can release drugs upon electrical stimulation, in this study antibiotics (penicillin/streptomycin, P/S) or an anti-inflammatory drug (dexamethasone, Dex), termed PPy[P/S] or PPy[Dex], respectively, were electrodeposited in PPy on titanium. The objective of the present study was to determine if such drugs can be released from PPy on demand and (by applying a voltage) control cellular behavior important for orthopedic applications. Results showed that PPy films possessed nanometer-scale roughness as analyzed by atomic force microscopy. X-ray photoelectron spectroscopy confirmed the presence of P/S and Dex encapsulated within the PPy films. Results from cyclic voltammetry showed that 80% of the drugs were released on demand when sweep voltages were applied for five cycles at a scan rate of 0.1 V s - 1. Furthermore, osteoblast (bone-forming cells) and fibroblast (fibrous tissue-forming cells) adhesion were determined on the PPy films. Results showed that PPy[Dex] enhanced osteoblast adhesion after 4 h of culture compared to plain Ti. PPy-Ti (with or without anionic drug doping) inhibited fibroblast adhesion compared to plain Ti. These in vitro results confirmed that electrodeposited PPy[P/S] and PPy[Dex] can release drugs on demand to potentially fight bacterial infection, reduce inflammation, promote bone growth or reduce fibroblast functions, further implicating the use of such materials as implant sensors.

  13. Electrically controlled drug release from nanostructured polypyrrole coated on titanium

    Energy Technology Data Exchange (ETDEWEB)

    Sirivisoot, Sirinrath; Pareta, Rajesh; Webster, Thomas J, E-mail: Thomas_Webster@Brown.edu [School of Engineering, Brown University, Providence, RI 02912 (United States)

    2011-02-25

    Previous studies have demonstrated that multi-walled carbon nanotubes grown out of anodized nanotubular titanium (MWNT-Ti) can be used as a sensing electrode for various biomedical applications; such sensors detected the redox reactions of certain molecules, specifically proteins deposited by osteoblasts during extracellular matrix bone formation. Since it is known that polypyrrole (PPy) can release drugs upon electrical stimulation, in this study antibiotics (penicillin/streptomycin, P/S) or an anti-inflammatory drug (dexamethasone, Dex), termed PPy[P/S] or PPy[Dex], respectively, were electrodeposited in PPy on titanium. The objective of the present study was to determine if such drugs can be released from PPy on demand and (by applying a voltage) control cellular behavior important for orthopedic applications. Results showed that PPy films possessed nanometer-scale roughness as analyzed by atomic force microscopy. X-ray photoelectron spectroscopy confirmed the presence of P/S and Dex encapsulated within the PPy films. Results from cyclic voltammetry showed that 80% of the drugs were released on demand when sweep voltages were applied for five cycles at a scan rate of 0.1 V s{sup -1}. Furthermore, osteoblast (bone-forming cells) and fibroblast (fibrous tissue-forming cells) adhesion were determined on the PPy films. Results showed that PPy[Dex] enhanced osteoblast adhesion after 4 h of culture compared to plain Ti. PPy-Ti (with or without anionic drug doping) inhibited fibroblast adhesion compared to plain Ti. These in vitro results confirmed that electrodeposited PPy[P/S] and PPy[Dex] can release drugs on demand to potentially fight bacterial infection, reduce inflammation, promote bone growth or reduce fibroblast functions, further implicating the use of such materials as implant sensors.

  14. Artificial Muscles Based on Electroactive Polymers as an Enabling Tool in Biomimetics

    Science.gov (United States)

    Bar-Cohen, Y.

    2007-01-01

    Evolution has resolved many of nature's challenges leading to working and lasting solutions that employ principles of physics, chemistry, mechanical engineering, materials science, and many other fields of science and engineering. Nature's inventions have always inspired human achievements leading to effective materials, structures, tools, mechanisms, processes, algorithms, methods, systems, and many other benefits. Some of the technologies that have emerged include artificial intelligence, artificial vision, and artificial muscles, where the latter is the moniker for electroactive polymers (EAPs). To take advantage of these materials and make them practical actuators, efforts are made worldwide to develop capabilities that are critical to the field infrastructure. Researchers are developing analytical model and comprehensive understanding of EAP materials response mechanism as well as effective processing and characterization techniques. The field is still in its emerging state and robust materials are still not readily available; however, in recent years, significant progress has been made and commercial products have already started to appear. In the current paper, the state-of-the-art and challenges to artificial muscles as well as their potential application to biomimetic mechanisms and devices are described and discussed.

  15. A concise review on smart polymers for controlled drug release.

    Science.gov (United States)

    Aghabegi Moghanjoughi, Arezou; Khoshnevis, Dorna; Zarrabi, Ali

    2016-06-01

    Design and synthesis of efficient drug delivery systems are of critical importance in health care management. Innovations in materials chemistry especially in polymer field allows introduction of advanced drug delivery systems since polymers could provide controlled release of drugs in predetermined doses over long periods, cyclic and tunable dosages. To this end, researchers have taken advantages of smart polymers since they can undergo large reversible, chemical, or physical fluctuations as responses to small changes in environmental conditions, for instance, in pH, temperature, light, and phase transition. The present review aims to highlight various kinds of smart polymers, which are used in controlled drug delivery systems as well as mechanisms of action and their applications.

  16. Factors controlling alkalisalt deposition in recovery boiler- release mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    McKeough, P.; Kylloenen, H.; Kurkela, M. [VTT Energy, Espoo (Finland). Process Technology Group

    1996-12-01

    As part of a cooperative effort to develop a model to describe the behaviour of inorganic compounds in kraft recovery boilers, an experimental investigation of the release of sulphur during black liquor pyrolysis has been undertaken. Previous to these studies, the mechanisms of sulphur release and the reasons for the observed effects of process conditions on sulphur release were very poorly understood. On the basis of the experimental results, the main reactions leading to sulphur release have been elucidated with a fair degree of certainty. Logical explanations for the variations of sulphur release with temperature and with liquor solids content have been proposed. The influence of pressure has been investigated in order to gain insights into the effects of mass transfer on the sulphur-release rate. In the near future, the research will be aimed at generating the kinetic data necessary for modelling the release of sulphur in the recovery furnace. (author)

  17. Promoting fertilizer use via controlled release of a bacteria-encapsulated film bag.

    Science.gov (United States)

    Wu, Chin-San

    2010-05-26

    A phosphate-solubilizing bacterium ( Burkholderia cepacia isolate) encapsulated in maleic anhydride (MA) grafted onto poly(butylene succinate adipate) (PBSA) and then combined with starch as film bag material (PBSA-g-MA/starch) incubated in a saline solution required approximately 20 days to deplete the starch in the film bags. Thereafter, the cell concentration in the saline solution increased significantly because of the release of cells from the severely destroyed film bags and also their growth by use of depolymerized PBSA-g-MA fragments as a substrate. The incubation proceeded for 60 days, by which time the PBSA-g-MA/starch composite had suffered a >80% weight loss. For practical application, effectiveness of the above-mentioned film bags was demonstrated because it could improve the absorbability of a fertilizer for plants and promote the growth of plants. As a result, it can avoid the accumulation of the phosphate in excess fertilizer that lead to the phenomenon of poor soils. These results demonstrate that PBSA-g-MA/starch can be used to encapsulate cells of an indigenous phosphate-solubilizing bacterium ( B. cepacia isolate) to form a controlled release of bacteria-encapsulated film bag (BEFB). The B. cepacia isolate was able to degrade the film bags material, causing cell release. Biodegradability of the film bags depended upon the type of material used, because the PBSA film bags were also degraded but to a lesser degree. The addition of starch made the film bags more biodegradable. The decrease in intrinsic viscosity was also higher for the starch composite, suggesting a strong connection between the biodegradability and these characteristics. The results suggest that the release of fertilizer-promoted bacteria might be controllable via a suitable film bag material formulation. In addition, this work adopted live bacteria to promote the absorption of phosphate, which is superior to the phosphate used in the traditional way.

  18. Uranium geochemistry in estuarine sediments: Controls on removal and release processes

    International Nuclear Information System (INIS)

    Barnes, C.E.; Cochran, J.K.

    1993-01-01

    Porewater uranium profiles from Long Island Sound (LIS) and Amazon shelf sediments and LIS sediment incubation experiments indicate that both removal and release processes control U geochemistry in estuarine sediments. Release of U from sediments occurs in association with Fe reduction. A correlation between U and Fe (and Mn) observed in sediment incubation experiments suggests that there is release of U from Fe-Mn-oxides as they are reduced, consistent with data from the Amazon shelf. In both sediment porewater profiles (LIS and Amazon) and sediment incubation experiments (LIS), there is removal of U from porewater under conditions of sulfate reduction. Sediment incubation experiments indicate that the removal rate is first-order with respect to U concentration, and the rate constant is linearly correlated to sulfate reduction rates. The link between U removal and sulfate reduction (a measure of diagenetic microbial activity) is consistent with a microbial mediation of U reduction. The diffusion flux of U into LIS sediments is estimated from porewater profiles. The inclusion of this estuarine removal term in the oceanic U balance increases the importance of the sediment sink. 62 refs., 12 figs., 2 tabs

  19. Nanocomposites for controlled release of nitrogen fertilizer

    International Nuclear Information System (INIS)

    Silva, Viviane J.M. da; Visconte, Leila L.Y.; Nascimento, Regina Sandra V.

    2009-01-01

    The study aimed at the development of nano structured materials capable of reducing the rate of release of nitrogen in the soil from an agricultural nitrogen fertilizer. Four different systems of polymer composites were prepared: (1) montmorillonite clay/fertilizer, (2) montmorillonite clay/thermoplastic starch and fertilizer, (3) montmorillonite clay/fertilizer, thermoplastic starch and low-density polyethylene (LDPE) and also (4) montmorillonite clay/fertilizer, thermoplastic starch and polycaprolactone. It was confirmed the formation of nano structured materials by elemental analysis (CHN) and X-ray diffraction (XRD). The kinetics of nitrogen release was detected by enzymatic colorimetric analysis and spectroscopy in the ultraviolet/visible. The results showed that all materials evaluated were able to reduce the rate of release of nitrogen in the fertilizers. (author)

  20. Controlled release of antibiotics encapsulated in the electrospinning polylactide nanofibrous scaffold and their antibacterial and biocompatible properties

    International Nuclear Information System (INIS)

    Wang, Shu-Dong; Zhang, Sheng-Zhong; Liu, Hua; Zhang, You-Zhu

    2014-01-01

    In this research, the drug loaded polylactide nanofibers are fabricated by electrospinning. Morphology, microstructure and mechanical properties are characterized. Properties and mechanism of the controlled release of the nanofibers are investigated. The results show that the drug loaded polylactide nanofibers do not show dispersed phase, and there is a good compatibility between polylactide and drugs. FTIR spectra show that drugs are encapsulated inside the polylactide nanofibers, and drugs do not break the structure of polylcatide. Flexibility of drug loaded polylactide scaffolds is higher than that of the pure polylactide nanofibers. Release rate of the drug loaded nanofibers is significantly slower than that of the drug powder. Release rate increases with the increase of the drugs’ concentration. The research mechanism suggests a typical diffusion-controlled release of the three loaded drugs. Antibacterial and cell culture show that drug loaded nanofibers possess effective antibacterial activity and biocompatible properties. (papers)

  1. Construction and evaluation of controlled-release delivery system of Abamectin using porous silica nanoparticles as carriers.

    Science.gov (United States)

    Wang, Yan; Cui, Haixin; Sun, Changjiao; Zhao, Xiang; Cui, Bo

    2014-12-01

    Photolysis and poor solubility in water of Abamectin are key issues to be addressed, which causes low bioavailability and residual pollution. In this study, a novel hydrophilic delivery system through loading Abamectin with porous silica nanoparticles (Abam-PSNs) was developed in order to improve the chemical stability, dispersity, and the controlled release of Abamectin. These results suggest that Abam-PSNs can significantly improve the performance of controllable release, photostability, and water solubility of Abamectin by changing the porous structure of silica nanoparticles, which is favorable to improve the bioavailability and reduce the residues of pesticides.

  2. Computer-aided and predictive models for design of controlled release of pesticides

    DEFF Research Database (Denmark)

    Suné, Nuria Muro; Gani, Rafiqul

    2004-01-01

    In the field of pesticide controlled release technology, a computer based model that can predict the delivery of the Active Ingredient (AI) from fabricated units is important for purposes of product design and marketing. A model for the release of an M from a microcapsule device is presented...... in this paper, together with a specific case study application to highlight its scope and significance. The paper also addresses the need for predictive models and proposes a computer aided modelling framework for achieving it through the development and introduction of reliable and predictive constitutive...... models. A group-contribution based model for one of the constitutive variables (AI solubility in polymers) is presented together with examples of application and validation....

  3. Comparison of the effect of ibuprofen and slow-released Diclofenac Sodium in controlling post endodontic pain

    Directory of Open Access Journals (Sweden)

    Saatchi M

    2010-01-01

    Full Text Available "nBackground and Aims: Despite the significant improvement in dentistry, pain after endodontic therapy is still of concern for patients. Non-steroidal anti-inflammatory drugs are the most commonly prescribed oral analgesics used for dental pain relief after root canal treatment. The purpose of this study was to compare the effectiveness of Ibuprofen versus slow-released Diclofenac Sodium in controlling pain following root canal treatment. "nMaterials and Methods: In this randomized clinical trial, mandibular molars with irreversible pulpitis in 90 patients were selected. The patients were divided into three groups (Ibuprofen, slow-released Diclofenac Sodium and placebo. After examination patients filled in the consent form. Then they received one of the mentioned drugs. After inferior alveolar nerve block, access cavity was prepared and the root canals were prepared using passive step back method. The canals were dried and temporary filling material was placed. Then the pain evaluation form (visual analog scale was explained and delivered to the patients. Data were analyzed using Repeated Measurement ANOVA, Kruskal-wallis and Man-Whitney U tests. "nResults: The mean pain intensity in slow-released Diclofenac Sodium group was 0.87 0.95, 1.17 1.10 for Ibuprofen group, and 2.14  1.70 for placebo group. The differences between groups were statistically significant (P<0.001. The effect of Ibuprofen in controlling post endodontic pain in the first 2 hours was more than slow-released Diclofenac Sodium (P=0.01, but in 10, 18, and 36 hours after treatment, slow-released Diclofenac Sodium was more effective than Ibuprofen (P<0.001. "nConclusion: Premedication with single dose of slow-released Diclofenac Sodium can control post endodontic pain for a longer period of time compared with Ibuprofen. "n.

  4. Tuning the Hydrophilic/Hydrophobic Balance to Control the Structure of Chitosan Films and Their Protein Release Behavior.

    Science.gov (United States)

    Becerra, Jose; Sudre, Guillaume; Royaud, Isabelle; Montserret, Roland; Verrier, Bernard; Rochas, Cyrille; Delair, Thierry; David, Laurent

    2017-05-01

    The control over the crystallinity of chitosan and chitosan/ovalbumin films can be achieved via an appropriate balance of the hydrophilic/hydrophobic interactions during the film formation process, which then controls the release kinetics of ovalbumin. Chitosan films were prepared by solvent casting. The presence of the anhydrous allomorph can be viewed as a probe of the hydrophobic conditions at the neutralization step. The semicrystalline structure, the swelling behavior of the films, the protein/chitosan interactions, and the release behavior of the films were impacted by the DA and the film processing parameters. At low DAs, the chitosan films neutralized in the solid state corresponded to the most hydrophobic environment, inducing the crystallization of the anhydrous allomorph with and without protein. The most hydrophilic conditions, leading to the hydrated allomorph, corresponded to non-neutralized films for the highest DAs. For the non-neutralized chitosan acetate (amorphous) films, the swelling increased when the DA decreased, whereas for the neutralized chitosan films, the swelling decreased. The in vitro release of ovalbumin (model protein) from chitosan films was controlled by their swelling behavior. For fast swelling films (DA = 45%), a burst effect was observed. On the contrary, a lag time was evidenced for DA = 2.5% with a limited release of the protein. Furthermore, by blending chitosans (DA = 2.5% and 45%), the release behavior was improved by reducing the burst effect and the lag time. The secondary structure of ovalbumin was partially maintained in the solid state, and the ovalbumin was released under its native form.

  5. Temperature-Controlled Encapsulation and Release of an Active Enzyme in the Cavity of a Self-Assembled DNA Nanocage

    DEFF Research Database (Denmark)

    Juul, Sissel; Iacovelli, Federico; Falconi, Mattia

    2013-01-01

    ABSTRACT We demonstrate temperature-controlled encapsulation and release of the enzyme horseradish peroxidase using a preassembled and covalently closed three-dimensional DNA cage structure as a controllable encapsulation device. The utilized cage structure was covalently closed and composed of 12...... to fold into hairpin structures. As demonstrated by gel-electrophoretic and fluorophore-quenching experiments this design imposed a temperature-controlled conformational transition capability to the structure, which allowed entrance or release of an enzyme cargo at 37 C while ensuring retainment...

  6. Controlled Release from Zein Matrices

    NARCIS (Netherlands)

    Bouman, Jacob; Belton, Peter; Venema, Paul; Linden, Van Der Erik; Vries, De Renko; Qi, Sheng

    2016-01-01

    Purpose: In earlier studies, the corn protein zein is found to be suitable as a sustained release agent, yet the range of drugs for which zein has been studied remains small. Here, zein is used as a sole excipient for drugs differing in hydrophobicity and isoelectric point: indomethacin,

  7. Lignin based controlled release coatings

    NARCIS (Netherlands)

    Mulder, W.J.; Gosselink, R.J.A.; Vingerhoeds, M.H.; Harmsen, P.F.H.; Eastham, D.

    2011-01-01

    Urea is a commonly used fertilizer. Due to its high water-solubility, misuse easily leads to excess nitrogen levels in the soil. The aim of this research was to develop an economically feasible and biodegradable slow-release coating for urea. For this purpose, lignin was selected as coating

  8. Building a polysaccharide hydrogel capsule delivery system for control release of ibuprofen.

    Science.gov (United States)

    Chen, Zhi; Wang, Ting; Yan, Qing

    2018-02-01

    Development of a delivery system which can effectively carry hydrophobic drugs and have pH response is becoming necessary. Here we demonstrate that through preparation of β-cyclodextrin polymer (β-CDP), a hydrophobic drug molecule of ibuprofen (IBU) was incorporated into our prepared β-CDP inner cavities, aiming to improve the poor water solubility of IBU. A core-shell capsule structure has been designed for achieving the drug pH targeted and sustained release. This delivery system was built with polysaccharide polymer of Sodium alginate (SA), sodium carboxymethylcellulose (CMC) and hydroxyethyl cellulose (HEC) by physical cross-linking. The drug pH-response control release is this hydrogel system's chief merit, which has potential value for synthesizing enteric capsule. Besides, due to our simple preparing strategy, optimal conditions can be readily determined and the synthesis process can be accurately controlled, leading to consistent and reproducible hydrogel capsules. In addition, phase-solubility method was used to investigate the solubilization effect of IBU by β-CDP. SEM was used to prove the forming of core and shell structure. FT-IR and 1 H-NMR were also used to perform structural characteristics. By the technique of UV determination, the pH targeted and sustained release study were also performed. The results have proved that our prepared polysaccharide hydrogel capsule delivery system has potential applications as oral drugs delivery in the field of biomedical materials.

  9. Coaxial PCL/PVA electrospun nanofibers: osseointegration enhancer and controlled drug release device

    International Nuclear Information System (INIS)

    Song, Wei; Shi, Tong; Ren, Weiping; Yu, Xiaowei; Markel, David C

    2013-01-01

    The failure of prosthesis after total joint replacement is mainly due to dysfunctional osseointegration and implant infection. There is a critical need for orthopedic implants that promote rapid osseointegration and prevent bacterial colonization, particularly when placed in bone compromised by disease or physiology of the patients. The aim of this study was to fabricate a novel coaxial electrospun polycaprolactone (PCL)/polyvinyl alcohol (PVA) core-sheath nanofiber (NF) blended with both hydroxyapatite nanorods (HA) and type I collagen (Col) (PCL Col /PVA HA ). Doxycycline (Doxy) and dexamethasone (Dex) were successfully incorporated into the PCL Col /PVA HA NFs for controlled release. The morphology, surface hydrophilicity and mechanical properties of the PCL/PVA NF mats were analyzed by scanning electron microscopy, water contact angle and atomic force microscopy. The PCL Col /PVA HA NFs are biocompatible and enhance the adhesion and proliferation of murine pre-osteoblastic MC3T3 cells. The release of Doxy and Dex from coaxial PCL Col /PVA HA NFs showed more controlled release compared with the blended NFs. Using an ex vivo porcine bone implantation model we found that the PCL Col /PVA HA NFs bind firmly on the titanium rod surface and the NFs coating remained intact on the surface of titanium rods after pullout. No disruption or delamination was observed after the pullout test. These findings indicate that PCL Col /PVA HA NFs encapsulating drugs have great potential in enhancing implant osseointegration and preventing implant infection. (paper)

  10. Coaxial PCL/PVA electrospun nanofibers: osseointegration enhancer and controlled drug release device.

    Science.gov (United States)

    Song, Wei; Yu, Xiaowei; Markel, David C; Shi, Tong; Ren, Weiping

    2013-09-01

    The failure of prosthesis after total joint replacement is mainly due to dysfunctional osseointegration and implant infection. There is a critical need for orthopedic implants that promote rapid osseointegration and prevent bacterial colonization, particularly when placed in bone compromised by disease or physiology of the patients. The aim of this study was to fabricate a novel coaxial electrospun polycaprolactone (PCL)/polyvinyl alcohol (PVA) core-sheath nanofiber (NF) blended with both hydroxyapatite nanorods (HA) and type I collagen (Col) (PCL(Col)/PVA(HA)). Doxycycline (Doxy) and dexamethasone (Dex) were successfully incorporated into the PCL(Col)/PVA(HA) NFs for controlled release. The morphology, surface hydrophilicity and mechanical properties of the PCL/PVA NF mats were analyzed by scanning electron microscopy, water contact angle and atomic force microscopy. The PCL(Col)/PVA(HA) NFs are biocompatible and enhance the adhesion and proliferation of murine pre-osteoblastic MC3T3 cells. The release of Doxy and Dex from coaxial PCL(Col)/PVA(HA) NFs showed more controlled release compared with the blended NFs. Using an ex vivo porcine bone implantation model we found that the PCL(Col)/PVA(HA) NFs bind firmly on the titanium rod surface and the NFs coating remained intact on the surface of titanium rods after pullout. No disruption or delamination was observed after the pullout test. These findings indicate that PCL(Col)/PVA(HA) NFs encapsulating drugs have great potential in enhancing implant osseointegration and preventing implant infection.

  11. Magnetic Active Agent Release System (MAARS): evaluation of a new way for a reproducible, externally controlled drug release into the small intestine.

    Science.gov (United States)

    Dietzel, Christian T; Richert, Hendryk; Abert, Sandra; Merkel, Ute; Hippius, Marion; Stallmach, Andreas

    2012-08-10

    Human absorption studies are used to test new drug candidates for their bioavailability in different regions of the gastrointestinal tract. In order to replace invasive techniques (e.g. oral or rectal intubation) a variety of externally controlled capsule-based drug release systems has been developed. Most of these use ionizing radiation, internal batteries, heating elements or even chemicals for the localization and disintegration process of the capsule. This embodies potential harms for volunteers and patients. We report about a novel technique called "Magnetic Active Agent Release System" (MAARS), which uses purely magnetic effects for this purpose. In our trial thirteen healthy volunteers underwent a complete monitoring and release procedure of 250 mg acetylsalicylic acid (ASA) targeting the flexura duodenojejunalis and the mid-part of the jejunum. During all experiments MAARS initiated a sufficient drug release and was well tolerated. Beside this we also could show that the absorption of ASA is about two times faster in the more proximal region of the flexura duodenojejunalis with a tmax of 47±13 min compared to the more distal jejunum with tmax values of 100±10 min (p=0.031). Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Monensin controlled-release intraruminal capsule for control of bloat in pastured dairy cows.

    Science.gov (United States)

    Lowe, L B; Ball, G J; Carruthers, V R; Dobos, R C; Lynch, G A; Moate, P J; Poole, P R; Valentine, S C

    1991-01-01

    Monensin, a polyether ionophore antibiotic, is potentially an important agent for bloat relief in dairy cows grazing temperate legume-based pasture. A series of studies was undertaken to determine the effect of monensin, when delivered continuously in the rumen of lactating dairy cows by means of controlled-release capsules (monensin CRC). Such devices release approximately 300 mg/head/day for 100 d. A short-term pilot study made at Ruakura, New Zealand, tested monensin CRC in cows selected for high susceptibility to bloat and grazing lucerne (Medicago sativa) or red clover (Trifolium pratense). Treatment significantly reduced the incidence of bloat, while milk yield and protein yield were increased. There was no effect on fat yield. Following the pilot study, 6 large-scale field experiments involving a total of 368 lactating dairy cows, were made in Australia and New Zealand to confirm the effectiveness of monensin CRC for bloat control and to measure the effect of such treatment on milk production and composition. A severe bloat problem occurred in 2 experiments, mild bloat occurred in 2 others, while no visual signs of bloat were observed in the remaining 2 experiments. Bloat was significantly (P less than 0.05) reduced by monensin CRC treatment when data was pooled over the 4 experiments in which bloat occurred. Daily milk yield was increased in all experiments from a mean of 17.7 in untreated groups to 18.8 kg/head/day (P less than 0.05) in monensin CRC-treated cows. Protein percentage was not affected by treatment, while there was a decrease from 4.29 to 4.10% fat, although total fat yield was not affected.(ABSTRACT TRUNCATED AT 250 WORDS)

  13. Dopamine D(1) receptor-mediated control of striatal acetylcholine release by endogenous dopamine.

    Science.gov (United States)

    Acquas, E; Di Chiara, G

    1999-10-27

    The role of dopamine D(1) and D(2) receptors in the control of acetylcholine release in the dorsal striatum by endogenous dopamine was investigated by monitoring with microdialysis the effect of the separate or combined administration of the dopamine D(1) receptor antagonist, SCH 39166 ¿(-)-trans-6,7,7a,8,9, 13b-exahydro-3-chloro-2-hydroxy-N-methyl-5H-benzo-[d]-nap hto-[2, 1b]-azepine hydrochloride¿ (50 microg/kg subcutaneous (s.c.)), of the dopamine D(2)/D(3) receptor agonist, quinpirole (trans-(-)-4aR, 4a,5,6,7,8,8a,9-octahydro-5-propyl-1H-pyrazolo-(3,4-g)-quinoline hydrochloride) (5 and 10 microg/kg s.c.), and of the D(3) receptor selective agonist, PD 128,907 [S(+)-(4aR,10bR)-3,4,4a, 10b-tetrahydro-4-propyl-2H,5H-[1]benzopyrano-[4,3-b]-1,4-oxazin -9-ol hydrochloride] (50 microg/kg s.c.), on in vivo dopamine and acetylcholine release. Microdialysis was performed with a Ringer containing low concentrations (0.01 microM) of the acetylcholinesterase inhibitor, neostigmine. Quinpirole (10 microg/kg s.c.) decreased striatal dopamine and acetylcholine release. Administration of PD 128,907 (50 microg/kg) decreased dopamine but failed to affect acetylcholine release. SCH 39166 (50 microg/kg s.c.) stimulated dopamine release and reduced acetylcholine release. Pretreatment with quinpirole reduced (5 microg/kg s.c.) or completely prevented (10 microg/kg s.c.) the stimulation of dopamine release elicited by SCH 39166 (50 microg/kg s.c.); on the other hand, pretreatment with quinpirole (5 and 10 microg/kg) potentiated the reduction of striatal acetylcholine release induced by SCH 39166 (50 microg/kg s.c.). Similarly, pretreatment with PD 128,907 (50 microg/kg) which prevented the increase of dopamine release induced by SCH 39166 (50 microg/kg), potentiated the reduction of striatal acetylcholine transmission elicited by SCH 39166. Thus, pretreatment with low doses of quinpirole or PD 128,907 influences in opposite manner the effect of SCH 39166 on striatal dopamine and

  14. Light-triggerable formulations for the intracellular controlled release of biomolecules.

    Science.gov (United States)

    Lino, Miguel M; Ferreira, Lino

    2018-05-01

    New therapies based on the use of biomolecules [e.g., proteins, peptides, and non-coding (nc)RNAs] have emerged during the past few years. Given their instability, adverse effects, and limited ability to cross cell membranes, delivery systems are required to fully reveal their biological potential. Sophisticated nanoformulations responsive to light offer an excellent opportunity for the controlled release of these biomolecules, enabling the control of timing, duration, location, and dosage. In this review, we discuss the design principles for the delivery of biomolecules, in particular proteins and RNA-based therapeutics, by light-triggerable formulations. We further discuss the opportunities offered by these formulations in terms of endosomal escape, as well as their limitations. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. The control of beads diameter of bead-on-string electrospun nanofibers and the corresponding release behaviors of embedded drugs

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tingxiao [Key Laboratory of Textile Science and Technology (Donghua University), Ministry of Education of China, Shanghai 201620 (China); College of Textiles, Donghua University, Shanghai 201620 (China); Ding, Xin, E-mail: xding@dhu.edu.cn [Key Laboratory of Textile Science and Technology (Donghua University), Ministry of Education of China, Shanghai 201620 (China); College of Textiles, Donghua University, Shanghai 201620 (China); Tian, Lingling, E-mail: lingling_tian@nus.edu.sg [Center of Nanofibers & Nanotechnology, Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore); Hu, Jiyong; Yang, Xudong [Key Laboratory of Textile Science and Technology (Donghua University), Ministry of Education of China, Shanghai 201620 (China); College of Textiles, Donghua University, Shanghai 201620 (China); Ramakrishna, Seeram [Center of Nanofibers & Nanotechnology, Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore); Guangdong-Hongkong-Macau Institute of CNS Regeneration (GHMICR), Jinan University, Guangzhou 510632 (China)

    2017-05-01

    Bead-on-string nanofibers, with appropriate control of the beads diameter, are potential fibrous structures for efficient encapsulation of particle drugs in micron scales and could achieve controlled drug release for tissue engineering applications. In this study, the beads diameter of electrospun bead-on-string nanofibers was controlled by adjusting the concentration of spinning polymer, poly (lactic-co-glycolic acid) (PLGA), and the solvent ratio of chloroform to acetone. The images of the scanning electron microscopy (SEM) suggested that bead-on-string nanofibers could be successfully obtained only with a certain range of PLGA solution concentration. Moreover, with the decrease in the solvent ratio of chloroform to acetone, the range was left-shifted towards a smaller concentration. In addition, increase in the PLGA solution concentration within the range the beads diameter became greater and the shape of the beads changed from oval to slender when increasing the PLGA concentration within the range. The bead-on-string nanofibers with different beads diameter were further used to load micro-particle drugs of tetracycline hydrochloride, as a model drug, to examine the release behavior of nanofibers scaffold. The release profiles of drug loaded bead-on-string nanofibers demonstrated the possibility to alleviate the burst drug release by means of beads diameter control. - Highlights: • Bead diameter of bead-on-string electrospun nanofibers was controlled by varying solvent ratio and polymer concentration. • The effect of the addition of particle drugs on BD of bead-on-string electrospun nanofibers was studied. • The corresponding release behaviors of nanofibers with different BD loading micro-particle drugs were investigated. • Bead-on-string nanofibers with bigger BD could alleviate the initial burst release.

  16. The control of beads diameter of bead-on-string electrospun nanofibers and the corresponding release behaviors of embedded drugs

    International Nuclear Information System (INIS)

    Li, Tingxiao; Ding, Xin; Tian, Lingling; Hu, Jiyong; Yang, Xudong; Ramakrishna, Seeram

    2017-01-01

    Bead-on-string nanofibers, with appropriate control of the beads diameter, are potential fibrous structures for efficient encapsulation of particle drugs in micron scales and could achieve controlled drug release for tissue engineering applications. In this study, the beads diameter of electrospun bead-on-string nanofibers was controlled by adjusting the concentration of spinning polymer, poly (lactic-co-glycolic acid) (PLGA), and the solvent ratio of chloroform to acetone. The images of the scanning electron microscopy (SEM) suggested that bead-on-string nanofibers could be successfully obtained only with a certain range of PLGA solution concentration. Moreover, with the decrease in the solvent ratio of chloroform to acetone, the range was left-shifted towards a smaller concentration. In addition, increase in the PLGA solution concentration within the range the beads diameter became greater and the shape of the beads changed from oval to slender when increasing the PLGA concentration within the range. The bead-on-string nanofibers with different beads diameter were further used to load micro-particle drugs of tetracycline hydrochloride, as a model drug, to examine the release behavior of nanofibers scaffold. The release profiles of drug loaded bead-on-string nanofibers demonstrated the possibility to alleviate the burst drug release by means of beads diameter control. - Highlights: • Bead diameter of bead-on-string electrospun nanofibers was controlled by varying solvent ratio and polymer concentration. • The effect of the addition of particle drugs on BD of bead-on-string electrospun nanofibers was studied. • The corresponding release behaviors of nanofibers with different BD loading micro-particle drugs were investigated. • Bead-on-string nanofibers with bigger BD could alleviate the initial burst release.

  17. N,O6-partially acetylated chitosan nanoparticles hydrophobically-modified for controlled release of steroids and vitamin E

    DEFF Research Database (Denmark)

    Quinones, Javier Perez; Gothelf, Kurt Vesterager; Kjems, Jørgen

    2013-01-01

    Diosgenin, two synthetic analogs of brassinosteroids, testosterone and dl-α-tocopherol were covalently linked to synthetic water-soluble N,O6-partially acetylated chitosan, for their controlled release. Drug linking was confirmed by FTIR spectroscopy and proton NMR. Conjugates were also character......Diosgenin, two synthetic analogs of brassinosteroids, testosterone and dl-α-tocopherol were covalently linked to synthetic water-soluble N,O6-partially acetylated chitosan, for their controlled release. Drug linking was confirmed by FTIR spectroscopy and proton NMR. Conjugates were also...

  18. EPICS release 3.11 specific documentation -- EPICS release notes for 3.11

    International Nuclear Information System (INIS)

    1994-01-01

    EPICS release 3.11 is now ready for user testing. A person who wants to set up a simplified application environment to boot an IOC and create databases using R3.11 should follow the directions in Appendix B, page 27, of the EPICS Source/Release Control Manual, Sept. 20, 1993. The R3.11 EPICS path at ANL/APS is /net/phebos/epics/R3.11 so the command to get the new release is /net/phebos/epics/R3.11/Unix/share/bin/getrel /net/phebos/epics/R3.11. An existing R3.8 short form report can be copied to this new directory and used to create a database. ANL/APS is currently testing an Application Developers Source/Release control system. It is not yet ready for general distribution. Attached are the EPICS R3.11 release notes

  19. Fabrication of Glucose-Sensitive Layer-by-Layer Films for Potential Controlled Insulin Release Applications

    Directory of Open Access Journals (Sweden)

    Talusan Timothy Jemuel E.

    2015-01-01

    Full Text Available Self-regulated drug delivery systems (DDS are potential alternative to the conventional method of introducing insulin to the body due to their controlled drug release mechanism. In this study, Layer-by-Layer technique was utlized to manufacture drug loaded, pH responsive thin films. Insulin was alternated with pH-sensitive, [2-(dimethyl amino ethyl aminoacrylate] (PDMAEMA and topped of with polymer/glucose oxidase (GOD layers. Similarly, films using a different polymer, namely Poly(Acrylic Acid (PAA were also fabricated. Exposure of the films to glucose solutions resulted to the production of gluconic acid causing a polymer conformation change due to protonation, thus releasing the embedded insulin. The insulin release was monitored by subjecting the dipping glucose solutions to Bradford Assay. Films exhibited a reversal in drug release profile in the presence of glucose as compared to without glucose. PAA films were also found out to release more insulin compared to that of the PDMAEMA films.The difference in the profile of the two films were due to different polymer-GOD interactions, since both films exhibited almost identical profiles when embedded with Poly(sodium 4-styrenesulfonate (PSS instead of GOD.

  20. Control of anoplophora glabripennis by releasing sterile insects

    International Nuclear Information System (INIS)

    Liu Xiaohui; Li Yongjun; Zhang Shuyong; Wang Endong; Lu Daguang

    2003-01-01

    An experiment to evaluate the effect of released sterile insects on reproduction of natural A. glabripennis population was conducted at a 30-hectare poplar tree forest in Ying County of Shanxi Province from July 10 to August 29, 2001. Though the releasing ratio was only about 2-5, results from different methods showed that the reproduction of natural A. glabripennis population was suppressed effectively by releasing sterile insects, and that hatch ratio of eggs laid by parent generation was about 20% and survival ratio of F1 progeny about 27%. (authors)

  1. Conductive polymers for controlled release and treatment of central nervous system injury

    Science.gov (United States)

    Saigal, Rajiv

    As one of the most devastating forms of neurotrauma, spinal cord injury remains a challenging clinical problem. The difficulties in treatment could potentially be resolved by better technologies for therapeutic delivery. In order to develop new approaches to treating central nervous system injury, this dissertation focused on using electrically-conductive polymers, controlled drug release, and stem cell transplantation. We first sought to enhance the therapeutic potential of neural stem cells by electrically increasing their production of neurotrophic factors (NTFs), important molecules for neuronal cell survival, differentiation, synaptic development, plasticity, and growth. We fabricated a new cell culture device for growing neural stem cells on a biocompatible, conductive polymer. Electrical stimulation via the polymer led to upregulation of NTF production by neural stem cells. This approach has the potential to enhance stem cell function while avoiding the pitfalls of genetic manipulation, possibly making stem cells more viable as a clinical therapy. Seeing the therapeutic potential of conductive polymers, we extended our studies to an in vivo model of spinal cord injury (SCI). Using a novel fabrication and extraction technique, a conductive polymer was fabricated to fit to the characteristic pathology that follows contusive SCI. Assessed via quantitative analysis of MR images, the conductive polymer significantly reduced compression of the injured spinal cord. Further characterizing astroglial and neuronal response of injured host tissue, we found significant neuronal sparing as a result of this treatment. The in vivo studies also demonstrated improved locomotor recovery mediated by a conductive polymer scaffold over a non-conductive control. We next sought to take advantage of conductive polymers for local, electronically-controlled release of drugs. Seeking to overcome reported limitations in drug delivery via polypyrrole, we first embedded drugs in poly

  2. A simple and rapid approach to evaluate the in vitro in vivo role of release controlling agent ethyl cellulose ether derivative polymer.

    Science.gov (United States)

    Akhlaq, Muhammad; Khan, Gul Majid; Jan, Syed Umer; Wahab, Abdul; Hussain, Abid; Nawaz, Asif; Abdelkader, Hamdy

    2014-11-01

    Diclofenac sodium (DCL-Na) conventional oral tablets exhibit serious side effects when given for a longer period leading to noncompliance. Controlled release matrix tablets of diclofenac sodium were formulated using simple blending (F-1), solvent evaporation (F-2) and co-precipitation techniques (F-3). Ethocel® Standard 7 FP Premium Polymer (15%) was used as a release controlling agent. Drug release study was conducted in 7.4 pH phosphate buffer solutions as dissolution medium in vitro. Pharmacokinetic parameters were evaluated using albino rabbits. Solvent evaporation technique was found to be the best release controlling technique thereby prolonging the release rate up to 24 hours. Accelerated stability studies of the optimized test formulation (F-2) did not show any significant change (prelease rate when stored for six months. A simple and rapid method was developed for DCL-Na active moiety using HPLC-UV at 276nm. The optimized test tablets (F-2) significantly (prelease. The study showed that once-daily controlled release matrix tablets of DCL-Na were successfully developed using Ethocel® Standard 7 FP Premium.

  3. Starch derivative-based superabsorbent with integration of water-retaining and controlled-release fertilizers.

    Science.gov (United States)

    Zhong, Kang; Lin, Zuan-Tao; Zheng, Xi-Liang; Jiang, Gang-Biao; Fang, Yu-Sheng; Mao, Xiao-Yun; Liao, Zong-Wen

    2013-02-15

    Phosphate rock (PHR), a traditional fertilizer, is abundant, but is hard to be utilized by plants. To improve the utilization of PHR, and to integrate water-retaining and controlled-release fertilizers, an agricultural superabsorbent polymer based on sulfonated corn starch/poly (acrylic acid) embedding phosphate rock (SCS/PAA/PHR) was prepared. PHR can be suspended and well-dispersed in SCS/PAA by sulfonated corn starch (SCS). PHR and KOH were mixed in acrylic acid solution to provide phosphorus (P) and potassium (K) nutrients, respectively. Impacts on water absorption capacity of the superabsorbent were investigated. The maximum swelling capacity in distilled water or 0.9 wt.% (weight percent) NaCl solution reached 498 g g(-1) and 65 g g(-1) (water/prepared dry superabsorbent) respectively. Moreover, release behaviours of P and K in SCS/PAA/PHR were also investigated. The results showed that SCS/PAA/PHR possessed excellent sustained-release property of plant nutrient, and the SCS/PAA could improve the P release greatly. Besides, the XPS analysis was employed to study the relationship between PHR and superabsorbent polymer. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Controlled Release of Indomethacin from Smart Starch-Based Hydrogels Prepared Acrylic Acid and b-Cyclodextrin as a Nanocarrier

    Directory of Open Access Journals (Sweden)

    Hossein Ghasemzadeh Mohammadi

    2017-01-01

    Full Text Available Controlled release of drugs can reduce the undesired effects of drug level fluctuations, and diminish the side effects as well as improve the therapeutic outcome of the drugs. In recent year, the scope of the drug delivery systems has been greatly expanded by the development of various hydrogels. The present work has focused on the design of a pH sensitive drug delivery system (DDS based on starch, acrylic acid (AA and β-cyclodextrins for controlled delivery of indomethacin. The hydrogels were prepared via graft polymerization of acrylic acid (AA onto starch and β-cyclodextrins backbones by a free radical polymerization technique. Cyclodextrins are able to form water-soluble complexes with many lipophilic water-insoluble drugs. In aqueous solutions, the drug molecules located in the central cavity of the cyclodextrin are in a dynamic equilibrium with free drug molecules. The interaction of drug with the polymer was evidenced by FTIR spectroscopy and thermal gravimetric analysis (TGA. The morphology of the samples was examined by scanning electron microscopy (SEM. The results showed that the hydrogels have good porosity and provided high surface area for the loading and release of drugs. Drug release behavior was carried out at physiological conditions of phosphate buffer, pH 8. In basic pH (like the intestine medium the hydrogels released the indomethacin, but in acidic pH (like the stomach medium there was no tendency to drug release. By increasing the amount of cyclodextrin, the rate of drug loading and release increased due to the dynamic equilibrium and interaction between the loaded drug and the cyclodextrin. This study has demonstrated that the hydrogel matrices are potentially suitable for controlled-release systems.

  5. WE-AB-BRA-03: Non-Invasive Controlled Release from Implantable Hydrogel Scaffolds Using Ultrasound

    Energy Technology Data Exchange (ETDEWEB)

    Moncion, A; Kripfgans, O.D; Putnam, A.J; Frances chi, R.T; Fabiilli, M.L [University of Michigan, Ann Arbor, MI (United States)

    2016-06-15

    Purpose: To control release of a model payload in acoustically responsive scaffolds (ARSs) using focused ultrasound (FUS). Methods: Fluorescently-labeled dextran (10 kDa) was encapsulated in sonosensitive perfluorocarbon (C{sub 6}F{sub 14} or C{sub 5}F{sub 12}) double emulsions (mean diameter: 2.9±0.1 µm). For in vitro release studies, 0.5 mL ARSs (10 mg/mL fibrin, 1% (v/v) emulsion) were polymerized in 24 well plates and covered with 0.5 mL medium. Starting one day after polymerization, ARSs were exposed to FUS (2.5 MHz, Pr = 8 MPa, 13 cycles, 100 Hz PRF) for 2 min daily. The amount of dextran released into the media was quantified. For in vivo studies, 0.25 mL ARSs were prepared as described previously and injected subcutaneously in the lower back of BALB/c mice. After polymerization, a subset of the implanted ARSs were exposed to FUS (as previously described). Animals were imaged longitudinally using a fluorescence imaging system to quantify the amount of dextran released from the ARSs. Results: In vitro: Over 6 days, +FUS displayed an 8.2-fold increase in dextran release compared to −FUS (−FUS: 2.7±0.6%; +FUS: 22.2±3.0%) for C{sub 6}F{sub 14} ARSs, and a 6.7-fold increase (−FUS: 5.0±0.8%; +FUS: 38.5±1.6%) for C{sub 5}F{sub 12}:C{sub 6}F{sub 14} ARSs. In vivo: +FUS displayed statistically greater dextran release compared to −FUS one day after implantation for C{sub 5}F{sub 12}:C{sub 6}F{sub 14} ARSs (−FUS: 55.1±1.5%; +FUS: 74.1±2.2%) and three days after implantation for C{sub 6}F{sub 14} ARSs (−FUS: 1.4±6.5%; +FUS: 30.4±5.4%). Conclusion: FUS enables non-invasive control of payload release from an ARS, which could benefit growth factor delivery for tissue regeneration. ARS are versatile due to their tunability (i.e. stiffness, emulsion composition, FUS pressure, FUS frequency, etc.) and can be modified to for optimal payload release. Future work will optimize ARS formulations for in vivo use to minimize payload release in the absence of

  6. Highly Controlled Diffusion Drug Release from Ureasil-Poly(ethylene oxide)-Na+-Montmorillonite Hybrid Hydrogel Nanocomposites.

    Science.gov (United States)

    Jesus, Celso R N; Molina, Eduardo F; Pulcinelli, Sandra H; Santilli, Celso V

    2018-06-06

    In this work, we report the effects of incorporation of variable amounts (1-20 wt %) of sodium montmorillonite (MMT) into a siloxane-poly(ethylene oxide) hybrid hydrogel prepared by the sol-gel route. The aim was to control the nanostructural features of the nanocomposite, improve the release profile of the sodium diclofenac (SDCF) drug, and optimize the swelling behavior of the hydrophilic matrix. The nanoscopic characteristics of the siloxane-cross-linked poly(ethylene oxide) network, the semicrystallinity of the hybrid, and the intercalated or exfoliated structure of the clay were investigated by X-ray diffraction, small-angle X-ray scattering, and differential scanning calorimetry. The correlation between the nanoscopic features of nanocomposites containing different amounts of MMT and the swelling behavior revealed the key role of exfoliated silicate in controlling the water uptake by means of a flow barrier effect. The release of the drug from the nanocomposite displayed a stepped pattern kinetically controlled by the diffusion of SDCF molecules through the mass transport barrier created by the exfoliated silicate. The sustained SDCF release provided by the hybrid hydrogel nanocomposite could be useful for the prolonged treatment of painful conditions, such as arthritis, sprains and strains, gout, migraine, and pain after surgical procedures.

  7. High energy density redox flow device

    Science.gov (United States)

    Chiang, Yet-Ming; Carter, William Craig; Duduta, Mihai; Limthongkul, Pimpa

    2014-05-13

    Redox flow devices are described including a positive electrode current collector, a negative electrode current collector, and an ion-permeable membrane separating said positive and negative current collectors, positioned and arranged to define a positive electroactive zone and a negative electroactive zone; wherein at least one of said positive and negative electroactive zone comprises a flowable semi-solid composition comprising ion storage compound particles capable of taking up or releasing said ions during operation of the cell, and wherein the ion storage compound particles have a polydisperse size distribution in which the finest particles present in at least 5 vol % of the total volume, is at least a factor of 5 smaller than the largest particles present in at least 5 vol % of the total volume.

  8. Doxorubicin loaded nanodiamond-silk spheres for fluorescence tracking and controlled drug release

    Science.gov (United States)

    Khalid, Asma; Mitropoulos, Alexander N.; Marelli, Benedetto; Tomljenovic-Hanic, Snjezana; Omenetto, Fiorenzo G.

    2015-01-01

    Nanoparticle (NP) based technologies have proved to be considerably beneficial for advances in biomedicine especially in the areas of disease detection, drug delivery and bioimaging. Over the last few decades, NPs have garnered interest for their exemplary impacts on the detection, treatment, and prevention of cancer. The full potential of these technologies are yet to be employed for clinical use. The ongoing research and development in this field demands single multifunctional composite materials that can be employed simultaneously for drug delivery and biomedical imaging. In this manuscript, a unique combination of silk fibroin (SF) and nanodiamonds (NDs) in the form of nanospheres are fabricated and investigated. The spheres were loaded with the anthracyline Doxorubicin (DoX) and the drug release kinetics for these ND-SF-DoX (NDSX) spheres were studied. NDs provided the fluorescence modality for imaging while the degradable SF spheres stabilized and released the drug in a controlled manner. The emission and structural properties of the spheres were characterized during drug release. The degradability of SF and the subsequent release of DoX from the spheres were monitored through fluorescence of NDs inside the spheres. This research demonstrates the enormous potential of the ND-SF nanocomposite platforms for diagnostic and therapeutic purposes, which are both important for pharmaceutical research and clinical settings. PMID:26819823

  9. Controlled release of bupivacaine using hybrid thermoresponsive nanoparticles activated via photothermal heating.

    Science.gov (United States)

    Alejo, Teresa; Andreu, Vanesa; Mendoza, Gracia; Sebastian, Victor; Arruebo, Manuel

    2018-08-01

    Near-infrared (NIR) responsive nanoparticles are of great interest in the biomedical field as antennas for photothermal therapy and also as triggers for on-demand drug delivery. The present work reports the preparation of hollow gold nanoparticles (HGNPs) with plasmonic absorption in the NIR region covalently bound to a thermoresponsive polymeric shell that can be used as an on-demand drug delivery system for the release of analgesic drugs. The photothermal heating induced by the nanoparticles is able to produce the collapse of the polymeric shell thus generating the release of the local anesthetic bupivacaine in a spatiotemporally controlled way. Those HGNPs contain a 10 wt.% of polymer and present excellent reversible heating under NIR light excitation. Bupivacaine released at physiological temperature (37 °C) showed a pseudo-zero order release that could be spatiotemporally modified on-demand after applying several pulses of light/temperature above and below the lower critical solution temperature (LCST) of the polymeric shell. Furthermore, the nanomaterials obtained did not displayed detrimental effects on four mammalian cell lines at doses up to 0.2 mg/mL. From the results obtained it can be concluded than this type of hybrid thermoresponsive nanoparticle can be used as an externally activated on-demand drug delivery system. Copyright © 2018 Elsevier Inc. All rights reserved.

  10. Design of a long-term antipsychotic in situ forming implant and its release control method and mechanism.

    Science.gov (United States)

    Wang, Lexi; Wang, Aiping; Zhao, Xiaolei; Liu, Ximing; Wang, Dan; Sun, Fengying; Li, Youxin

    2012-05-10

    Two kinds of in situ forming implants (ISFIs) of atypical antipsychotics, risperidone and its 9-hydroxy active metabolite, paliperidone, using poly(lactide-co-glycolide)(PLGA) as carrier, were investigated. Significant difference was observed in the solution-gel transition mechanism of the two systems: homogeneous system of N-methyl-2-pyrrolidone (NMP) ISFI, in which drug was dissolved, and heterogeneous system of dimethyl sulfoxide (DMSO) ISFI, in which drug was dispersed. Fast solvent extractions were found in both systems, but in comparison with the high drug release rate from homogeneous system of drug/polymer/NMP, a fast solvent extraction from the heterogeneous system of drug/polymer/DMSO was not accompanied by a high drug release rate but a rapid solidification of the implant, which resulted in a high drug retention, well-controlled initial burst and slow release of the drug. In vivo study on beagle dogs showed a more than 3-week sustained release with limited initial burst. Pharmacologic evaluation on optimized paliperidone ISFIs presented a sustained-suppressing effect from 1 day to 38 day on the MK-801 induced schizophrenic behavior mice model. A long sustained-release antipsychotic ISFI of 50% drug loading and controlled burst release was achieved, which indicated a good potential in clinic application. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Development of controlled release spheroids using Buchananiacochinchinesis gum

    Directory of Open Access Journals (Sweden)

    Narayan Babulal Gaikwad

    2013-03-01

    Full Text Available Chirauli nut gum was isolated from the bark of Buchanania cochinchinesis (fam. Anacadiacea and was used as a release modifier for the preparation of Diclofenac sodium spheroids using the extrusion spheronization technique. The process was studied for the effects on variables when making spheroids with satisfactory particle shape, size and size distribution. The prepared spheroids were characterized for surface morphology, qualitative surface porosity, friability, bulk density and flow properties. In vitro studies demonstrated that the release exhibited Fickian diffusion kinetics which was confirmed by the Higuchi and the Korsmeyer-Peppas models. The physico-chemical parameters of the gum could be correlated to the in vitro dissolution profile of the spheroids. The spheroids were not able to sustain the drug releases over 12 hours. A greater concentration of Chirauli nut gum and a process that can accommodate such greater concentrations may produce a formulation capable of significant sustained release.

  12. Evaluation of tecniques for controlling UF6 release clouds in the GAT environmental chamber

    International Nuclear Information System (INIS)

    Lux, C.J.

    1982-01-01

    Studies designed to characterize the reaction between UF 6 and atmospheric moisture, evaluate environmental variables of UF 6 cloud formation and ultimate cloud fate, and UF 6 release cloud control procedure have been conducted in the 1200 cu. ft. GAT environmental chamber. In earlier chamber experiments, 30 separate UF 6 release tests indicated that variations of atmospheric conditions and sample sizes had no significant effect on UO 2 F 2 particle size distribution, release cloud formation, or cloud settling rates. During the past year, numerous procedures have been evaluated for accelerating UF 6 cloud knockdown in a series of 37 environmental chamber releases. Knockdown procedures included: coarse water spray; air jet; steam spray (electrostatically charged and uncharged); carbon dioxide; Freon-12; fine water mist (uncharged); boric acid mist (charged and uncharged); and an ionized dry air stream. UF 6 hydrolysis cloud settling rates monitored by a laser/powermeter densitometer, indicated the relative effectiveness of various cloud knockdown techniques. Electrostatically charged boric acid/water mist, and electrostatically ionized dry air were both found to be very effective, knocking down the UO 2 F 2 release cloud particles in two to five minutes. Work to adapt these knockdown techniques for use under field conditions is continuing, taking into account recovery of the released uranium as well as nuclear criticality constraints

  13. Reductive electrografting of in situ produced diazopyridinium cations: Tailoring the interface between carbon electrodes and electroactive bacterial films.

    Science.gov (United States)

    Smida, Hassiba; Lebègue, Estelle; Bergamini, Jean-François; Barrière, Frédéric; Lagrost, Corinne

    2018-04-01

    Carbon electrodes were functionalized through the reduction of diazopyridinium cations that are produced from in situ diazotization of 2-, 3- and 4-aminopyridine. Diazopyridinium salts were much more rarely employed for surface functionalization than other aryldiazonium derivatives. A study combining X-ray Photoelectron Spectroscopy (XPS), contact angle, ellipsometry, Atomic Force Microscopy (AFM) measurements and electrochemical analyses demonstrates that films obtained from 4-diazopyridinium cations are hydrophilic, dense, compact but sufficiently thin to preserve fast electronic transfer rate, being then relevant to efficiently tailor the interface between the anode surface and an electroactive biofilm. Microbial Fuels Cells (MFCs) with pyridine-functionalized graphite anodes exhibit faster development and improved performances than MFCs operating with bare graphite anodes. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. UV-screening chitosan nanocontainers: increasing the photostability of encapsulated materials and controlled release

    International Nuclear Information System (INIS)

    Anumansirikul, Nattaporm; Wittayasuporn, Mayura; Klinubol, Patcharawalai; Tachaprutinun, A; Wanichwecharungruang, Supason P

    2008-01-01

    Methyl ether terminated poly(ethylene glycol)-4-methoxycinnamoylphthaloylchitosan (PCPLC), a UV absorptive polymer, and methyl ether terminated poly(ethylene glycol)-phthaloylchitosan (PPLC) were synthesized, characterized and self-assembled into stable water-dispersible spherical nanoparticles. The encapsulation of a model compound, 2-ethylhexyl-4-methoxycinnamate (EHMC), was carried out to give particles with 67% (w/w) EHMC loading. The E to Z photoisomerization of EHMC encapsulated inside both particles was monitored and compared to non-encapsulated EHMC. Minimal E to Z photoisomerization was observed when EHMC was encapsulated in PCPLC particles prepared from a polymer with a maximum degree of 4-methoxycinnamoyl substitution. The results indicated that the grafted UVB absorptive chromophore, 4-methoxycinnamoyl moieties, situated at the shell of PCPLC nanoparticles acted as a UV-filtering barrier, protecting the encapsulated EHMC from the UVB radiation, thus minimizing its photoisomerization. In vitro experiments revealed the pH-dependent controlled release of EHMC from PCPLC and PPLC particles. Ex vivo experiments, using a Franz diffusion cell with baby mouse skin, indicated that neither PPLC nor PCPLC particles could penetrate the skin into the receptor medium after a 24 h topical application. When applied on the baby mouse skin, both EHMC-encapsulated PPLC and EHMC-encapsulated PCPLC showed comparable controlled releases of the EHMC. The released EHMC could transdermally penetrate the baby mouse skin

  15. UV-screening chitosan nanocontainers: increasing the photostability of encapsulated materials and controlled release

    Science.gov (United States)

    Anumansirikul, Nattaporm; Wittayasuporn, Mayura; Klinubol, Patcharawalai; Tachaprutinun, A.; Wanichwecharungruang, Supason P.

    2008-05-01

    Methyl ether terminated poly(ethylene glycol)-4-methoxycinnamoylphthaloylchitosan (PCPLC), a UV absorptive polymer, and methyl ether terminated poly(ethylene glycol)-phthaloylchitosan (PPLC) were synthesized, characterized and self-assembled into stable water-dispersible spherical nanoparticles. The encapsulation of a model compound, 2-ethylhexyl-4-methoxycinnamate (EHMC), was carried out to give particles with 67% (w/w) EHMC loading. The E to Z photoisomerization of EHMC encapsulated inside both particles was monitored and compared to non-encapsulated EHMC. Minimal E to Z photoisomerization was observed when EHMC was encapsulated in PCPLC particles prepared from a polymer with a maximum degree of 4-methoxycinnamoyl substitution. The results indicated that the grafted UVB absorptive chromophore, 4-methoxycinnamoyl moieties, situated at the shell of PCPLC nanoparticles acted as a UV-filtering barrier, protecting the encapsulated EHMC from the UVB radiation, thus minimizing its photoisomerization. In vitro experiments revealed the pH-dependent controlled release of EHMC from PCPLC and PPLC particles. Ex vivo experiments, using a Franz diffusion cell with baby mouse skin, indicated that neither PPLC nor PCPLC particles could penetrate the skin into the receptor medium after a 24 h topical application. When applied on the baby mouse skin, both EHMC-encapsulated PPLC and EHMC-encapsulated PCPLC showed comparable controlled releases of the EHMC. The released EHMC could transdermally penetrate the baby mouse skin.

  16. The effect of solvents and hydrophilic additive on stable coating and controllable sirolimus release system for drug-eluting stent.

    Science.gov (United States)

    Kim, Seong Min; Park, Sung-Bin; Bedair, Tarek M; Kim, Man-Ho; Park, Bang Ju; Joung, Yoon Ki; Han, Dong Keun

    2017-09-01

    Various drug-eluting stents (DESs) have been developed to prevent restenosis after stent implantation. However, DES still needs to improve the drug-in-polymer coating stability and control of drug release for effective clinical treatment. In this study, the cobalt-chromium (CoCr) alloy surface was coated with biodegradable poly(D,L-lactide) (PDLLA) and sirolimus (SRL) mixed with hydrophilic Pluronic F127 additive by using ultrasonic spray coating system in order to achieve a stable coating surface and control SRL release. The degradation of PDLLA/SRL coating was studied under physiological solution. It was found that adding F127 reduced the degradation of PDLLA and improved the coating stability during 60days. The effects of organic solvent such as chloroform and tetrahydrofuran (THF) on the coating uniformity were also examined. It was revealed that THF produced a very smooth and uniform coating compared to chloroform. The patterns of in vitro drug release according to the type of organic solvent and hydrophilic additive proposed the possibility of controllable drug release design in DES. It was found that using F127 the drug release was sustained regardless of the organic solvent used. In addition, THF was able to get faster and controlled release profile when compared to chloroform. The structure of SRL molecules in different organic solvents was investigated using ultra-small angle neutron scattering. Furthermore, the structure of SRL is concentration-dependent in chloroform with tight nature under high concentration, but concentration-independent in THF. These results strongly demonstrated that coating stability and drug release patterns can be changed by physicochemical properties of various parameters such as organic solvents, additive, and coating strategy. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Modified gum Arabic hydrogels as matrices for controlled release of curcumin supramolecular complexes

    International Nuclear Information System (INIS)

    Gerola, Adriana P.; Silva, Danielle C.; Rubira, Adley F.; Muniz, Edvani C.

    2015-01-01

    Modified gum Arabic (GA) hydrogels show a pH-responsive behavior making them excellent matrices to be used for oral administration of drugs. Our goal is to study the behavior of those matrices in simulated gastric and intestinal fluids. In this work we will present how the methacrylation degree of GA, by using glycidyl methacrylate, can affect the properties of these hydrogels for controlled release. The drug used in this work is the curcumin (Cur). Cur is associated with numerous pharmacological activities, but their application is limited by the low water solubility. We will present some studies involving the formation of host-guest complexes between Cur and natural cyclodextrins. Both modified GA and hydrogels were characterized by different techniques. The kinetics release of Cur complex-containing modified GA hydrogels was studied to have an insight on the release mechanism and rate constants. Toxicity studies on undifferentiated and differentiated Caco-2 were also carried out. (author)

  18. Controlled release system for ametryn using polymer microspheres: Preparation, characterization and release kinetics in water

    International Nuclear Information System (INIS)

    Grillo, Renato; Pereira, Anderson do Espirito Santo; Ferreira Silva de Melo, Nathalie; Porto, Raquel Martins; Feitosa, Leandro Oliveira; Tonello, Paulo Sergio; Dias Filho, Newton L.; Rosa, Andre Henrique; Lima, Renata; Fraceto, Leonardo Fernandes

    2011-01-01

    The purpose of this work was to develop a modified release system for the herbicide ametryn by encapsulating the active substance in biodegradable polymer microparticles produced using the polymers poly(hydroxybutyrate) (PHB) or poly(hydroxybutyrate-valerate) (PHBV), in order to both improve the herbicidal action and reduce environmental toxicity. PHB or PHBV microparticles containing ametryn were prepared and the efficiencies of herbicide association and loading were evaluated, presenting similar values of approximately 40%. The microparticles were characterized by scanning electron microscopy (SEM), which showed that the average sizes of the PHB and PHBV microparticles were 5.92 ± 0.74 μm and 5.63 ± 0.68 μm, respectively. The ametryn release profile was modified when it was encapsulated in the microparticles, with slower and more sustained release compared to the release profile of pure ametryn. When ametryn was associated with the PHB and PHBV microparticles, the amount of herbicide released in the same period of time was significantly reduced, declining to 75% and 87%, respectively. For both types of microparticle (PHB and PHBV) the release of ametryn was by diffusion processes due to anomalous transport (governed by diffusion and relaxation of the polymer chains), which did not follow Fick's laws of diffusion. The results presented in this paper are promising, in view of the successful encapsulation of ametryn in PHB or PHBV polymer microparticles, and indications that this system may help reduce the impacts caused by the herbicide, making it an environmentally safer alternative.

  19. Environmental Release Prevention and Control Plan (ERP and CP) annual review and update for 1993

    International Nuclear Information System (INIS)

    Jannik, G.T.; Mamatey, A.; Arnett, M.

    1993-01-01

    In the Environmental Release Prevention and Control Plan (ERP and CP), WSRC made a commitment to conduct the following follow-up activities and actions: (1) Complete the action items developed in response to the findings and recommendation of the Environmental Release Prevention Taskteam (WSRC-RP-92-356). (2) Complete all batch and continuous release procedure revisions to incorporate the attributes that WSRC senior management required of each procedure. (3) DOE-SR Assistance Managers and WSRC counterparts to reach consensus and closure on the identified engineered solutions documented in the ERP and CP, develop and drive implementation of facility changes per the agreements. (4) Continue to analyze releases and monitor performance in accordance with the ERP and CP, and utilize the ALARA Release Guides Committee to drive improvements. (5) Conduct annual re-evaluations of the cost benefit analyses of the identified engineered solutions, and identify new options and alternatives for each outfall in response to site mission and facility changes. This report documents the efforts that have been completed over the past year in response to these commitments

  20. Controlled drug release from a novel injectable biodegradable microsphere/scaffold composite based on poly(propylene fumarate).

    Science.gov (United States)

    Kempen, Diederik H R; Lu, Lichun; Kim, Choll; Zhu, Xun; Dhert, Wouter J A; Currier, Bradford L; Yaszemski, Michael J

    2006-04-01

    The ideal biomaterial for the repair of bone defects is expected to have good mechanical properties, be fabricated easily into a desired shape, support cell attachment, allow controlled release of bioactive factors to induce bone formation, and biodegrade into nontoxic products to permit natural bone formation and remodeling. The synthetic polymer poly(propylene fumarate) (PPF) holds great promise as such a biomaterial. In previous work we developed poly(DL-lactic-co-glycolic acid) (PLGA) and PPF microspheres for the controlled delivery of bioactive molecules. This study presents an approach to incorporate these microspheres into an injectable, porous PPF scaffold. Model drug Texas red dextran (TRD) was encapsulated into biodegradable PLGA and PPF microspheres at 2 microg/mg microsphere. Five porous composite formulations were fabricated via a gas foaming technique by combining the injectable PPF paste with the PLGA or PPF microspheres at 100 or 250 mg microsphere per composite formulation, or a control aqueous TRD solution (200 microg per composite). All scaffolds had an interconnected pore network with an average porosity of 64.8 +/- 3.6%. The presence of microspheres in the composite scaffolds was confirmed by scanning electron microscopy and confocal microscopy. The composite scaffolds exhibited a sustained release of the model drug for at least 28 days and had minimal burst release during the initial phase of release, as compared to drug release from microspheres alone. The compressive moduli of the scaffolds were between 2.4 and 26.2 MPa after fabrication, and between 14.9 and 62.8 MPa after 28 days in PBS. The scaffolds containing PPF microspheres exhibited a significantly higher initial compressive modulus than those containing PLGA microspheres. Increasing the amount of microspheres in the composites was found to significantly decrease the initial compressive modulus. The novel injectable PPF-based microsphere/scaffold composites developed in this study

  1. Controlled Aloin Release from Crosslinked Polyacrylamide Hydrogels: Effects of Mesh Size, Electric Field Strength and a Conductive Polymer

    Directory of Open Access Journals (Sweden)

    Anuvat Sirivat

    2013-10-01

    Full Text Available The aim of this paper is to investigate the effects of hydrogel mesh size, a conductive polymer, and electric field strength on controlled drug delivery phenomena using drug-loaded polyacrylamide hydrogels prepared at various crosslinking ratios both with and without a conductive polymer system. Poly(p-phenylene vinylene, PPV, as the model conductive polymer, was used to study its ability to control aloin released from aloin-doped poly(p-phenylene vinylene/polyacrylamide hydrogel (aloin-doped PPV/PAAM. In the passive release, the diffusion of aloin from five aloin-doped PPV/PAAM hydrogel systems each was delayed ranging from during the first three hours to during the first 14 h due to the ionic interaction between the anionic drug and PPV. After the delayed periods, aloin could diffuse continuously into the buffer solution through the PAAM matrix. The amount of aloin released from the aloin-doped PPV/PAAM rose with increasing electric field strength as a result of the three mechanisms: the expansion of PPV chains inside the hydrogel, iontophoresis, and the electroporation of the matrix pore size, combined. Furthermore, the conductive polymer and the electric field could be used in combination to regulate the amount of release drug to a desired level, to control the release rate, and to switch the drug delivery on/off.

  2. Electroactive polymer actuators as artificial muscles: are they ready for bioinspired applications?

    International Nuclear Information System (INIS)

    Carpi, Federico; Kornbluh, Roy; Sommer-Larsen, Peter; Alici, Gursel

    2011-01-01

    Electroactive polymer (EAP) actuators are electrically responsive materials that have several characteristics in common with natural muscles. Thus, they are being studied as 'artificial muscles' for a variety of biomimetic motion applications. EAP materials are commonly classified into two major families: ionic EAPs, activated by an electrically induced transport of ions and/or solvent, and electronic EAPs, activated by electrostatic forces. Although several EAP materials and their properties have been known for many decades, they have found very limited applications. Such a trend has changed recently as a result of an effective synergy of at least three main factors: key scientific breakthroughs being achieved in some of the existing EAP technologies; unprecedented electromechanical properties being discovered in materials previously developed for different purposes; and higher concentration of efforts for industrial exploitation. As an outcome, after several years of basic research, today the EAP field is just starting to undergo transition from academia into commercialization, with significant investments from large companies. This paper presents a brief overview on the full range of EAP actuator types and the most significant areas of interest for applications. It is hoped that this overview can instruct the reader on how EAPs can enable bioinspired motion systems.

  3. Hierarchical Mesoporous Organosilica-Silica Core-Shell Nanoparticles Capable of Controlled Fungicide Release.

    Science.gov (United States)

    Luo, Leilei; Liang, Yucang; Erichsen, Egil Severin; Anwander, Reiner

    2018-05-17

    A new class of hierarchically structured mesoporous silica core-shell nanoparticles (HSMSCSNs) with a periodic mesoporous organosilica (PMO) core and a mesoporous silica (MS) shell is reported. The applied one-pot, two-step strategy allows rational control over the core/shell chemical composition, topology, and pore/particle size, simply by adjusting the reaction conditions in the presence of cetyltrimethylammonium bromide (CTAB) as structure-directing agent under basic conditions. The spherical, ethylene- or methylene-bridged PMO cores feature hexagonal (p6mm) or cage-like cubic symmetry (Pm3‾ n) depending on the organosilica precursor. The hexagonal MS shell was obtained by n-hexane-induced controlled hydrolysis of TEOS followed by directional co-assembly/condensation of silicate/CTAB composites at the PMO cores. The HSMSCSNs feature a hierarchical pore structure with pore diameters of about 2.7 and 5.6 nm in the core and shell domains, respectively. The core sizes and shell thicknesses are adjustable in the ranges of 90-275 and 15-50 nm, respectively, and the surface areas (max. 1300 m 2  g -1 ) and pore volumes (max. 1.83 cm 3  g -1 ) are among the highest reported for core-shell nanoparticles. The adsorption and controlled release of the fungicide propiconazole by the HSMSCSNs showed a three-stage release profile. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Guidance for Evaluating the Safety of Experimental Releases of Mosquitoes, Emphasizing Mark-Release-Recapture Techniques.

    Science.gov (United States)

    Benedict, Mark Q; Charlwood, J Derek; Harrington, Laura C; Lounibos, L Philip; Reisen, William K; Tabachnick, Walter J

    2018-01-01

    Experimental releases of mosquitoes are performed to understand characteristics of populations related to the biology, ability to transmit pathogens, and ultimately their control. In this article, we discuss considerations related to the safety of experimental releases of living mosquitoes, applying principles of good practice in vector biology that protect human health and comfort. We describe specific factors of experimental releases of mosquitoes that we believe are critical to inform institutional biosafety committees and similar review boards to which proposals to conduct mosquito release experiments have been submitted. In this study, "experimental releases" means those that do not significantly increase vector capacity or nuisance biting relative to the unperturbed natural baseline. This document specifically does not address releases of mosquitoes for ongoing control programs or trials of new control methods for which broader assessments of risk are required. It also does not address releases of transgenic or exotic (non-native) mosquito species, both of which require particular regulatory approval. Experimental releases may include females and males and evaluation must consider their effects based on the number released, their genotype and phenotype, the environment into which they are released, and postrelease collection activities. We consider whether increases of disease transmission and nuisance biting might result from proposed experimental releases against the backdrop of natural population size variation. We recommend that experimental releases be conducted in a manner that can be reasonably argued to have insignificant negative effects. Reviewers of proposals for experimental releases should expect applicants to provide such an argument based on evidence from similar studies and their planned activities. This document provides guidance for creating and evaluating such proposals.

  5. Distinct presynaptic control of dopamine release in striosomal and matrix areas of the cat caudate nucleus

    International Nuclear Information System (INIS)

    Kemel, M.L.; Desban, M.; Glowinski, J.; Gauchy, C.

    1989-01-01

    By use of a sensitive in vitro microsuperfusion method, the cholinergic presynaptic control of dopamine release was investigated in a prominent striosome (areas poor in acetylcholinesterase activity) located within the core of cat caudate nucleus and also in adjacent matrix area. The spontaneous release of [ 3 H]dopamine continuously synthesized from [ 3 H]tyrosine in the matrix area was found to be twice that in the striosomal area; the spontaneous and potassium-evoked releases of [ 3 H]dopamine were calcium-dependent in both compartments. With 10 -6 M tetrodotoxin, 5 x 10 -5 M acetylcholine stimulated [ 3 H]dopamine release in both striosomal and matrix areas, effects completely antagonized by atropine, thus showing the involvement of muscarinic receptors located on dopaminergic nerve terminals. Experiments without tetrodotoxin revealed a more complex regulation of dopamine release in the matrix: (i) in contrast to results seen in the striosome, acetylcholine induced only a transient stimulatory effect on matrix dopamine release. (ii) Although 10 -6 M atropine completely abolished the cholinergic stimulatory effect on [ 3 H]dopamine release in striosomal area, delayed and prolonged stimulation of [ 3 H] dopamine release was seen with atropine in the matrix. The latter effect was completely abolished by the nicotinic antagonist pempidine. Therefore, in the matrix, in addition to its direct (tetrodotoxin-insensitive) facilitatory action on [ 3 H]dopamine release, acetylcholine exerts two indirect (tetrodotoxin-sensitive) opposing effects: an inhibition and a stimulation of [ 3 H]dopamine release mediated by muscarinic and nicotinic receptors, respectively

  6. Cross-linked chitosan-dextran sulphate vehicle system for controlled release of ciprofloxaxin drug: An ophthalmic application

    Directory of Open Access Journals (Sweden)

    Chetan Chavan

    2017-01-01

    Full Text Available The major challenge associated with conventional eye-drop is the rapid drug loss due to precorneal defence barrier. In this context, controlled-release system of ciprofloxacin-conjugated chitosan (CS-Dextran sulphate (DS nanoparticles (NPs have been synthesized, to increase the bioavailability. The formulated drug delivery vehicle was evaluated for its therapeutic value in the simulated tear fluidat pH 7.4. Ophthalmic microbes were tested with this formulation, to confirm the drug efficacy; which showed conducive therapeutic values of both MIC and MBC. Ocular irritancy test was performed using HET-CAM test, which showed that the CS-DS system did not yield any vascular response, offering it to be a non-irritant to the ocular surface. The release studies showed monotonous controlled-release for duration of 21 h. A fine cross-linking between CS and DS has been demonstrated to form CS-DS NPs and their interaction with drug has been evaluated using conventional characterization tools.

  7. Hypoxia-induced angiogenesis is increased by the controlled release of deferoxiamine from gelatin hydrogels.

    Science.gov (United States)

    Saito, Takashi; Tabata, Yasuhiko

    2014-08-01

    The objective of this study is to design biodegradable hydrogels for the controlled release of deferoxiamine (DFO) and evaluate their biological activity. When the DFO was added to human umbilical vein endothelial cells cultured in 5.0% O2, the level of hypoxia-inducible factor-1α and vascular endothelial growth factor significantly increased compared with that without DFO. The expression of angiogenesis-related genes was accordingly increased by the DFO addition. An aqueous solution of mixed gelatin and DFO was freeze-dried, and dehydrothermally treated at 140°C for 24h to prepare a gelatin hydrogel incorporating DFO. In the release test with phosphate-buffered saline solution (PBS) at 37°C, an initial DFO release of 60% was observed, followed by no release. When placed in PBS containing collagenase, the hydrogel was enzymatically degraded with time, and consequently released DFO in a degradation-dependent manner. After the hydrogel incorporating DFO was injected intramuscularly into a mouse model of hind limb ischemia, the number of new blood vessels formed was significantly higher than that with free DFO and DFO-free hydrogel. It is concluded that the DFO-containing hydrogel shows promising for inducing angiogenesis locally. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  8. Dynamics of controlled release systems based on water-in-water emulsions: A general theory

    NARCIS (Netherlands)

    Sagis, L.M.C.

    2008-01-01

    Phase-separated biopolymer solutions, and aqueous dispersions of hydrogel beads, liposomes, polymersomes, aqueous polymer microcapsules, and colloidosomes are all examples of water-in-water emulsions. These systems can be used for encapsulation and controlled release purposes, in for example food or

  9. Formulation and evaluation of controlled-release of telmisartan microspheres: In vitro/in vivo study

    Directory of Open Access Journals (Sweden)

    Praveen Kumar Gaur

    2014-12-01

    Full Text Available The aim of this work was to design a controlled-release drug-delivery system for the angiotensin-II receptor antagonist drug telmisartan. Telmisartan was encapsulated with different EUDRAGIT polymers by an emulsion solvent evaporation technique and the physicochemical properties of the formulations were characterized. Using a solvent evaporation method, white spherical microspheres with particle sizes of 629.9–792.1 μm were produced. The in vitro drug release was studied in three different pH media (pH 1.2 for 2 hours, pH 6.8 for 4 hours, and pH 7.4 for 18 hours. The formulations were then evaluated for their pharmacokinetic parameters. The entrapment efficiency of these microspheres was between 58.6% and 90.56%. The obtained microspheres showed good flow properties, which were evaluated in terms of angle of repose (15.29–26.32, bulk and tapped densities (0.37–0.53 and 0.43–0.64, respectively, Carr indices and Hausner ratio (12.94–19.14% and 1.14–1.23, respectively. No drug release was observed in the simulated gastric medium up to 2 hours; however, a change in pH from 1.2 to 6.8 increased the drug release. At pH 7.4, formulations with EUDRAGIT RS 100 showed a steady drug release. The microsphere formulation TMRS-3 (i.e., microspheres containing 2-mg telmisartan gave the highest Cmax value (6.8641 μg/mL at 6 hours, which was three times higher than Cmax for telmisartan oral suspension (TOS. Correspondingly, the area under the curve for TMRS-3 was 8.5 times higher than TOS. Particle size and drug release depended on the nature and content of polymer used. The drug release mechanism of the TMRS-3 formulation can be explained using the Higuchi model. The controlled release of drug from TMRS-3 also provides for higher plasma drug content and improved bioavailability.

  10. Dry elixir formulations of dexibuprofen for controlled release and enhanced oral bioavailability.

    Science.gov (United States)

    Kim, Seo-Ryung; Kim, Jin-Ki; Park, Jeong-Sook; Kim, Chong-Kook

    2011-02-14

    The objective of this study was to achieve an optimal formulation of dexibuprofen dry elixir (DDE) for the improvement of dissolution rate and bioavailability. To control the release rate of dexibuprofen, Eudragit(®) RS was employed on the surface of DDE resulting in coated dexibuprofen dry elixir (CDDE). Physicochemical properties of DDE and CDDE such as particle size, SEM, DSC, and contents of dexibuprofen and ethanol were characterized. Pharmacokinetic parameters of dexibuprofen were evaluated in the rats after oral administration. The DDE and CDDE were spherical particles of 12 and 19 μm, respectively. The dexibuprofen and ethanol contents in the DDE were dependent on the amount of dextrin and maintained for 90 days. The dissolution rate and bioavailability of dexibuprofen loaded in dry elixir were increased compared with those of dexibuprofen powder. Moreover, coating DDE with Eudragit(®) RS retarded the dissolution rate of dexibuprofen from DDE without reducing the bioavailability. Our results suggest that CDDE may be potential oral dosage forms to control the release and to improve the bioavailability of poorly water-soluble dexibuprofen. Copyright © 2010 Elsevier B.V. All rights reserved.

  11. Novel Brassinosteroid-Modified Polyethylene Glycol Micelles for Controlled Release of Agrochemicals.

    Science.gov (United States)

    Pérez Quiñones, Javier; Brüggemann, Oliver; Kjems, Jørgen; Shahavi, Mohammad Hassan; Peniche Covas, Carlos

    2018-02-21

    Two synthetic analogues of brassinosteroids (DI31 and S7) exhibit good plant growth enhancer activity. However, their hydrophobicity and quick metabolism in plants have limited their application and benefits in agriculture. Our objective was to prepare novel brassinosteroid-modified polyethylene glycol (PEG) micelles to achieve controlled release with extended stability while retaining agrochemical activity. Spectroscopic studies confirmed quantitative disubstitution of studied PEGs with the brassinosteroids, while elemental analysis assessed purity of the synthesized conjugates. Conjugates were also characterized by X-ray diffraction and thermal analysis. Dynamic and static light scattering showed stable and homogeneous approximately spherical micelles with average hydrodynamic diameters of 22-120 nm and almost neutral ζ potential. Spherical 30-140 nm micelles were observed by electron microscopy. Sustained in vitro releases at pH 5.5 were extended up to 96 h. Prepared PEG micelles showed good agrochemical activity in the radish seed bioassay and no cytotoxicity to the human microvascular endothelial cell line in the MTS test.

  12. Degraded expression of learned feedforward control in movements released by startle.

    Science.gov (United States)

    Wright, Zachary A; Carlsen, Anthony N; MacKinnon, Colum D; Patton, James L

    2015-08-01

    Recent work has shown that preplanned motor programs can be rapidly released via fast conducting pathways using a startling acoustic stimulus. Our question was whether the startle-elicited response might also release a recently learned internal model, which draws on experience to predict and compensate for expected perturbations in a feedforward manner. Our initial investigation using adaptation to robotically produced forces showed some evidence of this, but the results were potentially confounded by co-contraction caused by startle. In this study, we eliminated this confound by asking subjects to make reaching movements in the presence of a visual distortion. Results show that a startle stimulus (1) decreased performance of the recently learned task and (2) reduced after-effect magnitude. Since the recall of learned control was reduced, but not eliminated during startle trials, we suggest that multiple neural centers (cortical and subcortical) are involved in such learning and adaptation. These findings have implications for motor training in areas such as piloting, teleoperation, sports, and rehabilitation.

  13. Controlled release profiles of dipyridamole from biodegradable microspheres on the base of poly(3-hydroxybutyrate.

    Directory of Open Access Journals (Sweden)

    2007-12-01

    Full Text Available Novel biodegradable microspheres on the base of poly(3-hydroxybutyrate (PHB designed for controlled release of antithrombotic drug, namely dipyridamole (DPD, have been kinetically studied. The profiles of release from the microspheres with different diameters 4, 9, 63, and 92 µm present the progression of nonlinear and linear stages. Diffusionkinetic equation describing both linear (PHB hydrolysis and nonlinear (diffusion stages of the DPD release profiles from the spherical subjects has been written down as the sum of two terms: desorption from the homogeneous sphere in accordance with diffusion mechanism and the zero-order release. In contrast to the diffusivity dependence on microsphere size, the constant characteristics (k of linearity are scarcely affected by the diameter of PHB microparticles. The view of the kinetic profiles as well as the low rate of DPD release are in satisfactory agreement with kinetics of weight loss measured in vitro for the PHB films. Taking into account kinetic results, we suppose that the degradation of both films and PHB microspheres is responsible for the linear stage of DPD release profiles. In the nearest future, combination of biodegradable PHB and DPD as a representative of proliferation cell inhibitors will give possibility to elaborate the novel injectable therapeutic system for a local, long-term, antiproliferative action.

  14. Optimization of primaquine diphosphate tablet formulation for controlled drug release using the mixture experimental design.

    Science.gov (United States)

    Duque, Marcelo Dutra; Kreidel, Rogério Nepomuceno; Taqueda, Maria Elena Santos; Baby, André Rolim; Kaneko, Telma Mary; Velasco, Maria Valéria Robles; Consiglieri, Vladi Olga

    2013-01-01

    A tablet formulation based on hydrophilic matrix with a controlled drug release was developed, and the effect of polymer concentrations on the release of primaquine diphosphate was evaluated. To achieve this purpose, a 20-run, four-factor with multiple constraints on the proportions of the components was employed to obtain tablet compositions. Drug release was determined by an in vitro dissolution study in phosphate buffer solution at pH 6.8. The polynomial fitted functions described the behavior of the mixture on simplex coordinate systems to study the effects of each factor (polymer) on tablet characteristics. Based on the response surface methodology, a tablet composition was optimized with the purpose of obtaining a primaquine diphosphate release closer to a zero order kinetic. This formulation released 85.22% of the drug for 8 h and its kinetic was studied regarding to Korsmeyer-Peppas model, (Adj-R(2) = 0.99295) which has confirmed that both diffusion and erosion were related to the mechanism of the drug release. The data from the optimized formulation were very close to the predictions from statistical analysis, demonstrating that mixture experimental design could be used to optimize primaquine diphosphate dissolution from hidroxypropylmethyl cellulose and polyethylene glycol matrix tablets.

  15. Oral controlled release drug delivery system and Characterization of oral tablets; A review

    OpenAIRE

    Muhammad Zaman; Junaid Qureshi; Hira Ejaz; Rai Muhammad Sarfraz; Hafeez ullah Khan; Fazal Rehman Sajid; Muhammad Shafiq ur Rehman

    2016-01-01

    Oral route of drug administration is considered as the safest and easiest route of drug administration. Control release drug delivery system is the emerging trend in the pharmaceuticals and the oral route is most suitable for such kind of drug delivery system. Oral route is more convenient for It all age group including both pediatric and geriatrics. There are various systems which are adopted to deliver drug in a controlled manner to different target sites through oral route. It includes dif...

  16. The Relationship Between the Evolution of an Internal Structure and Drug Dissolution from Controlled-Release Matrix Tablets.

    Science.gov (United States)

    Kulinowski, Piotr; Hudy, Wiktor; Mendyk, Aleksander; Juszczyk, Ewelina; Węglarz, Władysław P; Jachowicz, Renata; Dorożyński, Przemysław

    2016-06-01

    In the last decade, imaging has been introduced as a supplementary method to the dissolution tests, but a direct relationship of dissolution and imaging data has been almost completely overlooked. The purpose of this study was to assess the feasibility of relating magnetic resonance imaging (MRI) and dissolution data to elucidate dissolution profile features (i.e., kinetics, kinetics changes, and variability). Commercial, hydroxypropylmethyl cellulose-based quetiapine fumarate controlled-release matrix tablets were studied using the following two methods: (i) MRI inside the USP4 apparatus with subsequent machine learning-based image segmentation and (ii) dissolution testing with piecewise dissolution modeling. Obtained data were analyzed together using statistical data processing methods, including multiple linear regression. As a result, in this case, zeroth order release was found to be a consequence of internal structure evolution (interplay between region's areas-e.g., linear relationship between interface and core), which eventually resulted in core disappearance. Dry core disappearance had an impact on (i) changes in dissolution kinetics (from zeroth order to nonlinear) and (ii) an increase in variability of drug dissolution results. It can be concluded that it is feasible to parameterize changes in micro/meso morphology of hydrated, controlled release, swellable matrices using MRI to establish a causal relationship between the changes in morphology and drug dissolution. Presented results open new perspectives in practical application of combined MRI/dissolution to controlled-release drug products.

  17. Enzymatic- and temperature-sensitive controlled release of ultrasmall superparamagnetic iron oxides (USPIOs

    Directory of Open Access Journals (Sweden)

    Ortega Ryan A

    2011-02-01

    Full Text Available Abstract Background Drug and contrast agent delivery systems that achieve controlled release in the presence of enzymatic activity are becoming increasingly important, as enzymatic activity is a hallmark of a wide array of diseases, including cancer and atherosclerosis. Here, we have synthesized clusters of ultrasmall superparamagnetic iron oxides (USPIOs that sense enzymatic activity for applications in magnetic resonance imaging (MRI. To achieve this goal, we utilize amphiphilic poly(propylene sulfide-bl-poly(ethylene glycol (PPS-b-PEG copolymers, which are known to have excellent properties for smart delivery of drug and siRNA. Results Monodisperse PPS polymers were synthesized by anionic ring opening polymerization of propylene sulfide, and were sequentially reacted with commercially available heterobifunctional PEG reagents and then ssDNA sequences to fashion biofunctional PPS-bl-PEG copolymers. They were then combined with hydrophobic 12 nm USPIO cores in the thin-film hydration method to produce ssDNA-displaying USPIO micelles. Micelle populations displaying complementary ssDNA sequences were mixed to induce crosslinking of the USPIO micelles. By design, these crosslinking sequences contained an EcoRV cleavage site. Treatment of the clusters with EcoRV results in a loss of R2 negative contrast in the system. Further, the USPIO clusters demonstrate temperature sensitivity as evidenced by their reversible dispersion at ~75°C and re-clustering following return to room temperature. Conclusions This work demonstrates proof of concept of an enzymatically-actuatable and thermoresponsive system for dynamic biosensing applications. The platform exhibits controlled release of nanoparticles leading to changes in magnetic relaxation, enabling detection of enzymatic activity. Further, the presented functionalization scheme extends the scope of potential applications for PPS-b-PEG. Combined with previous findings using this polymer platform that

  18. Enzymatic- and temperature-sensitive controlled release of ultrasmall superparamagnetic iron oxides (USPIOs).

    Science.gov (United States)

    Yu, Shann S; Scherer, Randy L; Ortega, Ryan A; Bell, Charleson S; O'Neil, Conlin P; Hubbell, Jeffrey A; Giorgio, Todd D

    2011-02-27

    Drug and contrast agent delivery systems that achieve controlled release in the presence of enzymatic activity are becoming increasingly important, as enzymatic activity is a hallmark of a wide array of diseases, including cancer and atherosclerosis. Here, we have synthesized clusters of ultrasmall superparamagnetic iron oxides (USPIOs) that sense enzymatic activity for applications in magnetic resonance imaging (MRI). To achieve this goal, we utilize amphiphilic poly(propylene sulfide)-bl-poly(ethylene glycol) (PPS-b-PEG) copolymers, which are known to have excellent properties for smart delivery of drug and siRNA. Monodisperse PPS polymers were synthesized by anionic ring opening polymerization of propylene sulfide, and were sequentially reacted with commercially available heterobifunctional PEG reagents and then ssDNA sequences to fashion biofunctional PPS-bl-PEG copolymers. They were then combined with hydrophobic 12 nm USPIO cores in the thin-film hydration method to produce ssDNA-displaying USPIO micelles. Micelle populations displaying complementary ssDNA sequences were mixed to induce crosslinking of the USPIO micelles. By design, these crosslinking sequences contained an EcoRV cleavage site. Treatment of the clusters with EcoRV results in a loss of R2 negative contrast in the system. Further, the USPIO clusters demonstrate temperature sensitivity as evidenced by their reversible dispersion at ~75°C and re-clustering following return to room temperature. This work demonstrates proof of concept of an enzymatically-actuatable and thermoresponsive system for dynamic biosensing applications. The platform exhibits controlled release of nanoparticles leading to changes in magnetic relaxation, enabling detection of enzymatic activity. Further, the presented functionalization scheme extends the scope of potential applications for PPS-b-PEG. Combined with previous findings using this polymer platform that demonstrate controlled drug release in oxidative

  19. Controlled release of astaxanthin from nanoporous silicified-phospholipids assembled boron nitride complex for cosmetic applications

    Science.gov (United States)

    Lee, Hye Sun; Sung, Dae Kyung; Kim, Sung Hyun; Choi, Won Il; Hwang, Ee Tag; Choi, Doo Jin; Chang, Jeong Ho

    2017-12-01

    Nanoporous silicified-phospholipids assembled boron nitride (nSPLs@BN) powder was prepared and demonstrated for use in controlled release of anti-oxidant astaxanthin (AX) as a cosmetic application. The nanoporous silicified phospholipids (nSPLs) were obtained by the silicification with tetraethyl orthosilicate (TEOS) of the hydrophilic region of phospholipid bilayers. This process involved the co-assembly of chemically active phospholipid bilayers within the porous silica matrix. In addition, nSPLs@BN was characterized using several analytical techniques and tested to assess their efficiency as drug delivery systems. We calculated the maximum release amounts as a function of time and various pH. The release rate of AX from the nSPLs@BN for the initial 24 h was 10.7 μmol/(h mg) at pH 7.4. Furthermore, we determined the antioxidant activity (KD) for the released AX with DPPH (1,1-diphenyl-2-picryl-hydrazyl) radical and the result was 34.6%.

  20. Emulsion-based encapsulation and delivery of nanoparticles for the controlled release of alkalinity within the subsurface environment

    Science.gov (United States)

    Ramsburg, C. A.; Muller, K.; Gill, J.

    2012-12-01

    Many current approaches to managing groundwater contamination rely on further advances in amendment delivery in order to initiate and sustain contaminant degradation or immobilization. In fact, limited or ineffective delivery is often cited when treatment objectives are not attained. Emulsions, specifically oil-in-water emulsions, have demonstrated potential to aid delivery of remediation amendments. Emulsions also afford opportunities to control the release of active ingredients encapsulated within the droplets. Our research is currently focused on the controlled release of nanoparticle-based buffering agents using oil-in-water emulsions. This interest is motivated by the fact that chemical and biological processes employed for the remediation and stewardship of contaminated sites often necessitate control of pH during treatment and, in some cases, long thereafter. Alkalinity-release nanoparticles (e.g., CaCO3, MgO) were suspended within soybean oil and subsequently encapsulated by through the creation of oil-in-water emulsions. These oil-in-water emulsions are designed to have physical properties which are favorable for subsurface delivery (nominal properties: 1 g/mL density; 10 cP viscosity; and 1.5 μm droplet diameter). Buffer capacity titrations suggest that MgO particles are moderately more accessible within the oil phase and nearly twice as effective (on a per mass basis) at releasing alkalinity (as compared to the CaCO3 particles). Results from experiments designed to assess the release kinetics suggest that a linear driving force model is capable of describing the release process and mass transfer coefficients are constant through the reactive life of the emulsion. The release kinetics in emulsions containing MgO particles were found to be three orders of magnitude faster than those quantified for emulsions containing CaCO3. The slower release kinetics of the emulsions containing CaCO3 particles may prove beneficial when considering pH control at sites