WorldWideScience

Sample records for controlled protein release

  1. Electrospun biodegradable nanofiber nonwovens for controlled release of proteins.

    Science.gov (United States)

    Maretschek, Sascha; Greiner, Andreas; Kissel, Thomas

    2008-04-21

    Electrospinning of emulsions composed of an organic poly(l-lactide) solution and an aqueous protein solution yielded protein containing nanofiber nonwovens (NNs) having a mean fiber diameter of approximately 350 nm. Cytochrome C was chosen as a hydrophilic model protein for encapsulation. SEM imaging and gas adsorption measurements were carried out to determine morphology and surface characteristics of the different nanofiber nonwovens. Transmission electron microscopy was used to clarify the localization of the protein within the NN. PLLA NNs exhibited a highly hydrophobic surface which led to a slow wetting. It was shown that the protein release was dependent on the surface tension of the release medium. Electrospinning of emulsions consisting of an organic solution of PLLA and an aqueous solution of hydrophilic polymers yielded fibers composed of a polymer blend. The resulting NNs exhibited a less hydrophobic surface, which gave us the opportunity to tailor the release profile via this technology. Furthermore it was investigated how the addition of different amounts of hydrophilic polymer to the aqueous phase influenced the morphology of the resulting NNs.

  2. Affinity hydrogels for controlled protein release using nucleic acid aptamers and complementary oligonucleotides.

    Science.gov (United States)

    Soontornworajit, Boonchoy; Zhou, Jing; Snipes, Matthew P; Battig, Mark R; Wang, Yong

    2011-10-01

    Biomaterials for the precise control of protein release are important to the development of new strategies for treating human diseases. This study aimed to fundamentally understand aptamer--protein dissociation triggered by complementary oligonucleotides, and to apply this understanding to develop affinity hydrogels for controlled protein release. The results showed that the oligonucleotide tails of the aptamers played a critical role in inducing intermolecular hybridization and triggering aptamer--protein dissociation. In addition, the attachment of the oligonucleotide tails to the aptamers and the increase of hybridizing length could produce a synergistic effect on the dissociation of bound proteins from their aptamers. More importantly, pegylated complementary oligonucleotides could successfully trigger protein release from the aptamer-functionalized hydrogels at multiple time points. Based on these results, it is believed that aptamer-functionalized hydrogels and complementary oligonucleotides hold great potential of controlling the release of protein drugs to treat human diseases.

  3. Designer protein delivery: From natural to engineered affinity-controlled release systems.

    Science.gov (United States)

    Pakulska, Malgosia M; Miersch, Shane; Shoichet, Molly S

    2016-03-18

    Exploiting binding affinities between molecules is an established practice in many fields, including biochemical separations, diagnostics, and drug development; however, using these affinities to control biomolecule release is a more recent strategy. Affinity-controlled release takes advantage of the reversible nature of noncovalent interactions between a therapeutic protein and a binding partner to slow the diffusive release of the protein from a vehicle. This process, in contrast to degradation-controlled sustained-release formulations such as poly(lactic-co-glycolic acid) microspheres, is controlled through the strength of the binding interaction, the binding kinetics, and the concentration of binding partners. In the context of affinity-controlled release--and specifically the discovery or design of binding partners--we review advances in in vitro selection and directed evolution of proteins, peptides, and oligonucleotides (aptamers), aided by computational design.

  4. Design of cationic microspheres based on aminated gelatin for controlled release of peptide and protein drugs.

    Science.gov (United States)

    Morimoto, Kazuhiro; Chono, Sumio; Kosai, Tadashi; Seki, Toshinobu; Tabata, Yasuhiko

    2008-02-01

    Two different types of cationized microspheres based on a native cationic gelatin (NGMS) and aminated gelatin with ethylendiamine (CGMS) were investigated for the controlled release of three model acidic peptide/protein drugs with different molecular weights (MWs) and isoelectric points (IEPs). Recombinant human (rh)-insulin (MW: 5.8 kDa, IEP: 5.3), bovine milk lactoalbumin, BMLA (MW: 14 kDa, IEP: 4.3), and bovine serum albumin (BSA MW: 67 kDa, IEP: 4.9) were used as model acidic peptide/protein drugs. The in vitro release profiles of these acidic peptide/protein drugs from NGMS and CGMS were compared and different periods of cross-linking were obtained. The slower release of these acidic peptide/protein drugs from CGMS compared with those from NGMS with cross-linking for 48 hr. was caused by the suppression of burst release during the initial phase. The degree of suppression of burst release of the three peptide/protein drugs during the initial phase by CGMS was in the following order: (rh)-insulin > BMLA > BSA. The release of insulin with a lower molecular weight from CGMS was particularly suppressed compared with the other two drugs with higher molecular weights in the initial phase. The control of the release rate of acidic peptide/protein drugs from gelatin microsphere can be achieved by amination of gelatin. Therefore, CGMS is useful for the controlled release of acidic peptide/ protein drugs.

  5. Controlled release of NELL-1 protein from chitosan/hydroxyapatite-modified TCP particles.

    Science.gov (United States)

    Zhang, Yulong; Dong, Rui; Park, Yujin; Bohner, Marc; Zhang, Xinli; Ting, Kang; Soo, Chia; Wu, Benjamin M

    2016-09-10

    NEL-like molecule-1 (NELL-1) is a novel osteogenic protein that showing high specificity to osteochondral cells. It was widely used in bone regeneration research by loading onto carriers such as tricalcium phosphate (TCP) particles. However, there has been little research on protein controlled release from this material and its potential application. In this study, TCP was first modified with a hydroxyapatite coating followed by a chitosan coating to prepare chitosan/hydroxyapatite-coated TCP particles (Chi/HA-TCP). The preparation was characterized by SEM, EDX, FTIR, XRD, FM and Zeta potential measurements. The NELL-1 loaded Chi/HA-TCP particles and the release kinetics were investigated in vitro. It was observed that the Chi/HA-TCP particles prepared with the 0.3% (wt/wt) chitosan solution were able to successfully control the release of NELL-1 and maintain a slow, steady release for up to 28 days. Furthermore, more than 78% of the loaded protein's bioactivity was preserved in Chi/HA-TCP particles over the period of the investigation, which was significantly higher than that of the protein released from hydroxyapatite coated TCP (HA-TCP) particles. Collectively, this study suggests that the osteogenic protein NELL-1 showed a sustained release pattern after being encapsulated into the modified Chi/HA-TCP particles, and the NELL-1 integrated composite of Chi/HA-TCP showed a potential to function as a protein delivery carrier and as an improved bone matrix for use in bone regeneration research.

  6. Controlled release of bovine serum albumin from hydroxyapatite microspheres for protein delivery system

    Energy Technology Data Exchange (ETDEWEB)

    Boonsongrit, Yaowalak [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Abe, Hiroya [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Cooperative Research Center of Life Sciences, Kobe Gakuin University, Minatojima 1-1-3, Chuo-ku, Kobe 650-8586 (Japan)], E-mail: h-abe@jwri.osaka-u.ac.jp; Sato, Kazuyoshi [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Naito, Makio [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Cooperative Research Center of Life Sciences, Kobe Gakuin University, Minatojima 1-1-3, Chuo-ku, Kobe 650-8586 (Japan); Yoshimura, Masahiro [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Ichikawa, Hideki; Fukumori, Yoshinobu [Faculty of Pharmaceutical Sciences, Kobe Gakuin University, Minatojima 1-1-3, Chuo-ku, Kobe 650-8586 (Japan); Cooperative Research Center of Life Sciences, Kobe Gakuin University, Minatojima 1-1-3, Chuo-ku, Kobe 650-8586 (Japan)

    2008-02-25

    Desorption behavior of a model protein (bovine serum albumin, BSA) on commercial hydroxyapatite (HAp) microspheres and its control were investigated for protein delivery system. The desorption behavior related strongly to the phosphate concentration in phosphate buffer solution: the amount of desorbed BSA increased when the phosphate concentration increased. In physiological buffer solution, which contains 10 mM phosphate, the initial burst release of BSA was observed: 70% of BSA was rapidly desorbed after 0.5 h, and 80% after 24 h. In contrast, the extremely low release profile of BSA was observed in distilled water. For the controlled release of BSA in physiological condition, the BSA-loaded HAp microspheres were encapsulated with a biodegradable polymer, poly(lactic acid-co-glycolic acid) (PLGA) by a solid-in oil-in water (S/O/W) emulsion solvent evaporation method. The initial burst was significantly reduced, and the BSA release was remarkably prolonged by the encapsulation.

  7. Protein capsules with cross-linked, semipermeable, and enzyme-degradable surface barriers for controlled release.

    Science.gov (United States)

    Zhou, Jianhua; Hyun, Dong Choon; Liu, Hang; Wu, Hongkai; Xia, Younan

    2014-08-01

    This paper describes a method for fabricating protein-based capsules with semipermeable and enzyme-degradable surface barriers. It involves the use of a simple fluidic device to generate water-in-oil emulsion droplets, followed by cross-linking of proteins at the water-oil interface to generate a semipermeable surface barrier. The capsules can be readily fabricated with uniform and controllable sizes and, more importantly, show selective permeability toward molecules with different molecular weights: small molecules like fluorescein sodium salt can freely diffuse through the surface barrier while macromolecules such as proteins can not. The proteins, however, can be released by digesting the surface barrier with an enzyme such as pepsin. Taken together, the capsules hold great potential for applications in controlled release, in particular, for the delivery of protein drugs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Hydrogel based drug carriers for controlled release of hydrophobic drugs and proteins

    NARCIS (Netherlands)

    Ke Peng,

    2011-01-01

    The aim of this study is to prepare in situ forming hydrogels based on biocompatible polymers for the controlled release of hydrophobic drug and proteins. In order to load hydrophobic drug to the hydrophilic hydrogel matrix, beta-cyclodextrin and human serum albumin was introduced to the hydrogel ne

  9. Controlled protein delivery from electrospun non-wovens: novel combination of protein crystals and a biodegradable release matrix.

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    Puhl, Sebastian; Li, Linhao; Meinel, Lorenz; Germershaus, Oliver

    2014-07-07

    Poly-ε-caprolactone (PCL) is an excellent polymer for electrospinning and matrix-controlled drug delivery combining optimal processability and good biocompatibility. Electrospinning of proteins has been shown to be challenging via the use of organic solvents, frequently resulting in protein unfolding or aggregation. Encapsulation of protein crystals represents an attractive but largely unexplored alternative to established protein encapsulation techniques because of increased thermodynamic stability and improved solvent resistance of the crystalline state. We herein explore the electrospinning of protein crystal suspensions and establish basic design principles for this novel type of protein delivery system. PCL was deployed as a matrix, and lysozyme was used as a crystallizing model protein. By rational combination of lysozyme crystals 0.7 or 2.1 μm in diameter and a PCL fiber diameter between 1.6 and 10 μm, release within the first 24 h could be varied between approximately 10 and 100%. Lysozyme loading of PCL microfibers between 0.5 and 5% was achieved without affecting processability. While relative release was unaffected by loading percentage, the amount of lysozyme released could be tailored. PCL was blended with poly(ethylene glycol) and poly(lactic-co-glycolic acid) to further modify the release rate. Under optimized conditions, an almost constant lysozyme release over 11 weeks was achieved.

  10. The Transcription Factor NIN-LIKE PROTEIN7 Controls Border-Like Cell Release.

    Science.gov (United States)

    Karve, Rucha; Suárez-Román, Frank; Iyer-Pascuzzi, Anjali S

    2016-07-01

    The root cap covers the tip of the root and functions to protect the root from environmental stress. Cells in the last layer of the root cap are known as border cells, or border-like cells (BLCs) in Arabidopsis (Arabidopsis thaliana). These cells separate from the rest of the root cap and are released from its edge as a layer of living cells. BLC release is developmentally regulated, but the mechanism is largely unknown. Here, we show that the transcription factor NIN-LIKE PROTEIN7 (NLP7) is required for the proper release of BLCs in Arabidopsis. Mutations in NLP7 lead to BLCs that are released as single cells instead of an entire layer. NLP7 is highly expressed in BLCs and is activated by exposure to low pH, a condition that causes BLCs to be released as single cells. Mutations in NLP7 lead to decreased levels of cellulose and pectin. Cell wall-loosening enzymes such as CELLULASE5 (CEL5) and a pectin lyase-like gene, as well as the root cap regulators SOMBRERO and BEARSKIN1/2, are activated in nlp7-1 seedlings. Double mutant analysis revealed that the nlp7-1 phenotype depends on the expression level of CEL5 Mutations in NLP7 lead to an increase in susceptibility to a root-infecting fungal pathogen. Together, these data suggest that NLP7 controls the release of BLCs by acting through the cell wall-loosening enzyme CEL5.

  11. Core-shell microparticles for protein sequestration and controlled release of a protein-laden core.

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    Rinker, Torri E; Philbrick, Brandon D; Temenoff, Johnna S

    2016-12-21

    Development of multifunctional biomaterials that sequester, isolate, and redeliver cell-secreted proteins at a specific timepoint may be required to achieve the level of temporal control needed to more fully regulate tissue regeneration and repair. In response, we fabricated core-shell heparin-poly(ethylene-glycol) (PEG) microparticles (MPs) with a degradable PEG-based shell that can temporally control delivery of protein-laden heparin MPs. Core-shell MPs were fabricated via a re-emulsification technique and the number of heparin MPs per PEG-based shell could be tuned by varying the mass of heparin MPs in the precursor PEG phase. When heparin MPs were loaded with bone morphogenetic protein-2 (BMP-2) and then encapsulated into core-shell MPs, degradable core-shell MPs initiated similar C2C12 cell alkaline phosphatase (ALP) activity as the soluble control, while non-degradable core-shell MPs initiated a significantly lower response (85+19% vs. 9.0+4.8% of the soluble control, respectively). Similarly, when degradable core-shell MPs were formed and then loaded with BMP-2, they induced a ∼7-fold higher C2C12 ALP activity than the soluble control. As C2C12 ALP activity was enhanced by BMP-2, these studies indicated that degradable core-shell MPs were able to deliver a bioactive, BMP-2-laden heparin MP core. Overall, these dynamic core-shell MPs have the potential to sequester, isolate, and then redeliver proteins attached to a heparin core to initiate a cell response, which could be of great benefit to tissue regeneration applications requiring tight temporal control over protein presentation.

  12. Controlled release of protein from biodegradable multi-sensitive injectable poly(ether-urethane) hydrogel.

    Science.gov (United States)

    Li, Xiaomeng; Wang, Yangyun; Chen, Jiaming; Wang, Yinong; Ma, Jianbiao; Wu, Guolin

    2014-03-12

    The synthesis and characterization of multi-sensitive polymers for use as injectable hydrogels for controlled protein/drug delivery is reported. A series of biodegradable multi-sensitive poly(ether-urethane)s were prepared through a simple one-pot condensation of poly(ethylene glycol), 2,2'-dithiodiethanol, N-methyldiethanolamine, and hexamethylene diisocyanate. The sol-gel phase transition behaviors of the obtained copolymers were investigated. Experimental results showed that the aqueous medium comprising the multi-segment copolymers underwent a sol-to-gel phase transition with increasing temperature and pH. At a certain concentration, the copolymer solution could immediately change to a gel under physiological conditions (37 °C and pH 7.4), indicating their suitability as in situ injectable hydrogels in vivo. Insulin was used as a model protein drug for evaluation of the injectable hydrogels as a site-specific drug delivery system. The controlled release of insulin from the hydrogel devices was demonstrated by degradation of the copolymer, which is modulated via the 2,2'-dithiodiethanol content in the poly(ether-urethane)s. These hydrogels having multi-responsive properties may prove to be promising candidates for injectable and controllable protein drug delivery devices.

  13. Controlled release behaviour of protein-loaded microparticles prepared via coaxial or emulsion electrospray.

    Science.gov (United States)

    Wang, Ying; Yang, Xiaoping; Liu, Wentao; Zhang, Feng; Cai, Qing; Deng, Xuliang

    2013-01-01

    Biodegradable poly (lactic-co-glycolic acid) (PLGA) microparticles are an effective way to achieve sustained drug release. In this study, we investigated a sustained release model of PLGA microparticles with incorporated protein via either emulsion or coaxial electrospray techniques. PLGA (75:25) was used as the carrier, and bovine serum albumin as a model protein. Coaxial electrospray resulted in a type of core-shell structure with mean diameters of 2.41 ± 0.60 µm and a centralised protein distribution within the core. Emulsion electrospray formed bigger microparticles with mean diameters of 22.75 ± 8.05 µm and a heterogeneous protein distribution throughout the microparticles. The coaxial electrospray microparticles presented a much slighter burst release than the emulsion electrospray microparticles. Loading efficiency was significantly higher (p coaxial group than emulsion group. This indicated that both emulsion and coaxial electrospray could produce protein-loaded microparticles with sustained release behaviour, but the former revealed a superior approach for drug delivery.

  14. A stimuli-responsive nanoparticulate system using poly(ethylenimine)-graft-polysorbate for controlled protein release

    Science.gov (United States)

    Lai, Wing-Fu; Shum, Ho Cheung

    2015-12-01

    Proteins have emerged as an important class of therapeutic agents due to their high specificity in their physiological actions. Over the years, diverse protein carriers have been developed; however, some concerns, such as the relatively low loading efficiency and release sustainability, have limited the efficiency of protein delivery. This study reports the use of hydrogel nanoparticles based on a novel copolymer, poly(ethylenimine)-graft-polysorbate (PEIP), as effective protein carriers. The copolymer is fabricated by grafting poly(ethylenimine) (PEI) with polysorbate 20 using carbonyldiimidazole chemistry. Its cytotoxicity is much lower than that of unmodified PEI in RGC5 and HEK293 cells. In comparison with nanoparticles formed by unmodified PEI, our nanoparticles are not only more efficient in cellular internalization, as indicated by the 5- to 6-fold reduction in the time they take to cause 90% of cells to exhibit intracellular fluorescence, but also give a protein loading efficiency as high as 70-90%. These, together with the salt-responsiveness of the nanoparticles in protein release and the retention of the activity of the loaded protein, suggest that PEIP and its hydrogel nanoparticles warrant further development as protein carriers for therapeutic applications.

  15. Controlled release process to recover heterologous glycosylphosphatidylinositol membrane anchored proteins from CHO cells.

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    Kennard, M L; Food, M R; Jefferies, W A; Piret, J M

    1993-08-05

    A semicontinuous process has been developed to recover heterologous proteins at increased concentrations and purities. Proteins attached to mammalian cell membranes by glycosylphosphatidylinositol (GPI) anchors can be selectively released into the supernatant by the enzyme phosphatidylinositol-phospholipase C (PI-PLC). Chinese hamster ovary (CHO) cells, genetically engineered to express the GPI anchored, human melanoma antigen (p97), were used as a model system. These cells were grown in protein containing growth medium. During a brief harvesting phase the medium was replaced by phosphate buffered saline (PBS) containing 10 mU/mL of PI-PLC and the GPI anchored protein was cleaved from the cell surface and recovered in soluble form at up to 30% purity. After harvesting, the cells were returned to growth medium where the protein was re-expressed within 40 h. The growth rate, viability, and protein production of cells, repeatedly harvested over a 44-day period, were not adversely affected. This continuous cyclic harvesting process allowed recovery of a heterologous protein at high purity and concentrations and could be applied to the recovery of other GPI anchored proteins and genetically engineered GPI anchored fusion proteins. (c) 1993 John Wiley & Sons, Inc.

  16. Block copolymer micelles as nanocontainers for controlled release of proteins from biocompatible oil phases.

    Science.gov (United States)

    Miller, Andrew C; Bershteyn, Anna; Tan, Wuisiew; Hammond, Paula T; Cohen, Robert E; Irvine, Darrell J

    2009-04-13

    Biocompatible oils are used in a variety of medical applications ranging from vaccine adjuvants to vehicles for oral drug delivery. To enable such nonpolar organic phases to serve as reservoirs for delivery of hydrophilic compounds, we explored the ability of block copolymer micelles in organic solvents to sequester proteins for sustained release across an oil-water interface. Self-assembly of the block copolymer, poly(-caprolactone)-block-poly(2-vinyl pyridine) (PCL-b-P2VP), was investigated in toluene and oleic acid, a biocompatible naturally occurring fatty acid. Micelle formation in toluene was characterized by dynamic light scattering (DLS) and atomic force microscopy (AFM) imaging of micelles cast onto silicon substrates. Cryogenic transmission electron microscopy confirmed a spherical morphology in oleic acid. Studies of homopolymer solubility implied that micelles in oleic acid consist of a P2VP corona and a PCL core, while P2VP formed the core of micelles assembled in toluene. The loading of two model proteins (ovalbumin (ova) and bovine serum albumin (BSA)) into micelles was demonstrated with loadings as high as 7.8% wt of protein per wt of P2VP in oleic acid. Characterization of block copolymer morphology in the two solvents after protein loading revealed spherical particles with similar size distributions to the as-assembled micelles. Release of ova from micelles in oleic acid was sustained for 12-30 h upon placing the oil phase in contact with an aqueous bath. Unique to the situation of micelle assembly in an oily phase, the data suggest protein is sequestered in the P2VP corona block of PCL-b-P2VP micelles in oleic acid. More conventionally, protein loading occurs in the P2VP core of micelles assembled in toluene.

  17. Controlled-release and preserved bioactivity of proteins from (self-assembled core-shell double-walled microspheres

    Directory of Open Access Journals (Sweden)

    Yuan W

    2012-01-01

    Full Text Available Weien Yuan1,2, Zhenguo Liu11Department of Neurology, Xinhua Hospital, affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 2School of Pharmacy, Shanghai Jiao Tong University, Shanghai, People’s Republic of ChinaAbstract: In order to address preserved protein bioactivities and protein sustained-release problems, a method for preparing double-walled microspheres with a core (protein-loaded nanoparticles with a polymer-suspended granule system-formed core and a second shell (a polymer-formed shell for controlled drug release and preserved protein bioactivities has been developed using (solid-in-oil phase-in-hydrophilic oil-in-water (S/O/Oh/W phases. The method, based on our previous microsphere preparation method (solid-in-oil phase-in-hydrophilic oil-in-water (S/O/Oh/W, employs different concentric poly(D,L-lactide-co-glycolide, poly(D,L-lactide, and protein-loaded nanoparticles to produce a suspended liquid which then self-assembles to form shell-core microspheres in the hydrophilic oil phase, which are then solidified in the water phase. Variations in the preparation parameters allowed complete encapsulation by the shell phase, including the efficient formation of a poly(D,L-lactide shell encapsulating a protein-loaded nanoparticle-based poly(D,L-lactide-co-glycolide core. This method produces core-shell double-walled microspheres that show controlled protein release and preserved protein bioactivities for 60 days. Based upon these results, we concluded that the core-shell double-walled microspheres might be applied for tissue engineering and therapy for chronic diseases, etc.Keywords: protein delivery, protein stability, core-shell microspheres, dextran nanoparticles

  18. Controlled protein release from electrospun biodegradable fiber mesh composed of poly(epsilon-caprolactone) and poly(ethylene oxide).

    Science.gov (United States)

    Kim, Taek Gyoung; Lee, Doo Sung; Park, Tae Gwan

    2007-06-29

    A blend mixture of poly(epsilon-caprolactone) (PCL) and poly(ethylene oxide) (PEO) was electrospun to produce fibrous meshes that could release a protein drug in a controlled manner. Various biodegradable polymers, such as poly(l-lactic acid) (PLLA), poly(epsilon-caprolactone) (PCL), and poly(d,l-lactic-co-glycolic acid) (PLGA) were dissolved, along with PEO and lysozyme, in a mixture of chloroform and dimethylsulfoxide (DMSO). The mixture was electrospun to produce lysozyme loaded fibrous meshes. Among the polymers, the PCL/PEO blend meshes showed good morphological stability upon incubation in the buffer solution, resulting in controlled release of lysozyme over an extended period with reduced initial bursts. With varying the PCL/PEO blending ratio, the release rate of lysozyme from the corresponding meshes could be readily modulated. The lysozyme release was facilitated by increasing the amount of PEO, indicating that entrapped lysozyme was mainly released out by controlled dissolution of PEO from the blend meshes. Lysozyme released from the electrospun fibers retained sufficient catalytic activity.

  19. Translationally Controlled Tumor Protein Stimulates Dopamine Release from PC12 Cells via Ca(2+)-Independent Phospholipase A₂ Pathways.

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    Seo, Jihui; Maeng, Jeehye; Kim, Hwa-Jung

    2016-10-24

    The translationally controlled tumor protein (TCTP), initially identified as a tumor- and growth-related protein, is also known as a histamine-releasing factor (HRF). TCTP is widely distributed in the neuronal systems, but its function is largely uncharacterized. Here, we report a novel function of TCTP in the neurotransmitter release from a neurosecretory, pheochromocytoma (PC12) cells. Treatment with recombinant TCTP (rTCTP) enhanced both basal and depolarization (50 mM KCl)-evoked [³H]dopamine release in concentration- and time-dependent manners. Interestingly, even though rTCTP induced the increase in intracellular calcium levels ([Ca(2+)]i), the rTCTP-driven effect on dopamine release was mediated by a Ca(2+)-independent pathway, as evidenced by the fact that Ca(2+)-modulating agents such as Ca(2+) chelators and a voltage-gated L-type Ca(2+)-channel blocker did not produce any changes in rTCTP-evoked dopamine release. In a study to investigate the involvement of phospholipase A₂ (PLA₂) in rTCTP-induced dopamine release, the inhibitor for Ca(2+)-independent PLA₂ (iPLA₂) produced a significant inhibitory effect on rTCTP-induced dopamine release, whereas this release was not significantly inhibited by Ca(2+)-dependent cytosolic PLA₂ (cPLA₂) and secretory PLA₂ (sPLA₂) inhibitors. We found that rTCTP-induced dopamine release from neuronal PC12 cells was modulated by a Ca(2+)-independent mechanism that involved PLA₂ in the process, suggesting the regulatory role of TCTP in the neuronal functions.

  20. Translationally Controlled Tumor Protein Stimulates Dopamine Release from PC12 Cells via Ca2+-Independent Phospholipase A2 Pathways

    Directory of Open Access Journals (Sweden)

    Jihui Seo

    2016-10-01

    Full Text Available The translationally controlled tumor protein (TCTP, initially identified as a tumor- and growth-related protein, is also known as a histamine-releasing factor (HRF. TCTP is widely distributed in the neuronal systems, but its function is largely uncharacterized. Here, we report a novel function of TCTP in the neurotransmitter release from a neurosecretory, pheochromocytoma (PC12 cells. Treatment with recombinant TCTP (rTCTP enhanced both basal and depolarization (50 mM KCl-evoked [3H]dopamine release in concentration- and time-dependent manners. Interestingly, even though rTCTP induced the increase in intracellular calcium levels ([Ca2+]i, the rTCTP-driven effect on dopamine release was mediated by a Ca2+-independent pathway, as evidenced by the fact that Ca2+-modulating agents such as Ca2+ chelators and a voltage-gated L-type Ca2+-channel blocker did not produce any changes in rTCTP-evoked dopamine release. In a study to investigate the involvement of phospholipase A2 (PLA2 in rTCTP-induced dopamine release, the inhibitor for Ca2+-independent PLA2 (iPLA2 produced a significant inhibitory effect on rTCTP-induced dopamine release, whereas this release was not significantly inhibited by Ca2+-dependent cytosolic PLA2 (cPLA2 and secretory PLA2 (sPLA2 inhibitors. We found that rTCTP-induced dopamine release from neuronal PC12 cells was modulated by a Ca2+-independent mechanism that involved PLA2 in the process, suggesting the regulatory role of TCTP in the neuronal functions.

  1. Tunable Controlled Release of Bioactive SDF-1α via Protein Specific Interactions within Fibrin/Nanoparticle Composites.

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    Dutta, D; Fauer, C; Mulleneux, H L; Stabenfeldt, S E

    2015-10-31

    The chemokine, stromal cell-derived factor 1α (SDF-1α), is a key regulator of the endogenous neural progenitor/stem cell-mediated regenerative response after neural injury. Increased and sustained bioavailability of SDF-1α in the peri-injury region is hypothesized to modulate this endogenous repair response. Here, we describe poly(lactic-co-glycolic) acid (PLGA) nanoparticles capable of releasing bioactive SDF-1α in a sustained manner over 60days after a burst of 23%. Moreover, we report a biphasic cellular response to SDF-1α concentrations thus the large initial burst release in an in vivo setting may result in supratherapeutic concentrations of SDF-1α. Specific protein-protein interactions between SDF-1α and fibrin (as well as its monomer, fibrinogen) were exploited to control the magnitude of the burst release. Nanoparticles embedded in fibrin significantly reduced the amount of SDF-1α released after 72 hrs as a function of fibrin density. Therefore, the nanoparticle/fibrin composites represented a means to independently tune the magnitude of the burst phase release from the nanoparticles while perserving a bioactive depot of SDF-1α for release over 60days.

  2. Controlled release from recombinant polymers.

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    Price, Robert; Poursaid, Azadeh; Ghandehari, Hamidreza

    2014-09-28

    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.

  3. Hydrogel Layers on the Surface of Polyester-Based Materials for Improvement of Their Biointeractions and Controlled Release of Proteins

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    Viktor Korzhikov-Vlakh

    2016-12-01

    Full Text Available The modification of bioresorbable polyester surfaces in order to alter their biointeractions presents an important problem in biomedical polymer science. In this study, the covalent modification of the surface of poly(lactic acid-based (PLA-based films with poly(acryl amide and sodium alginate hydrogels was performed to change the non-specific polyester interaction with proteins and cells, as well as to make possible the covalent attachment of low-molecular weight ligands and to control protein release. The effect of such modification on the film surface properties was studied. Parameters such as swelling, water contact angle, surface area, and binding capacity of low-molecular weight substances were evaluated and compared. The comparative study of adsorption of model protein (BSA on the surface of non-modified and modified films was investigated and the protein release was evaluated. Cell viability on the surface of hydrogel-coated films was also tested. The developed approach could be applied for the modification of PLA-based scaffolds for tissue engineering and will be further studied for molecular-imprinting of biomolecules on the surface of polyester-based materials for control of biointeractions.

  4. A new method for the production of gelatin microparticles for controlled protein release from porous polymeric scaffolds.

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    Ozkizilcik, Asya; Tuzlakoglu, Kadriye

    2014-03-01

    Tissue engineering using scaffolds and growth factors is a crucial approach in bone regeneration and repair. The combination of bioactive agents carrying microparticles with porous scaffolds can be an efficient solution when controlled release of bio-signalling molecules is required. The present study was based on a recent approach using a biodegradable scaffold and protein-loaded microparticles produced in an innovative manner in which protein loss is minimized during the loading process. Bovine serum albumin (BSA)-loaded gelatin microparticles were obtained by grinding freeze-dried membranes of gelatin and BSA. Porous scaffolds (250-355 µm pore size) produced from a polyactide (PLLA) and polycaprolactone (PCL) blend by salt leaching/supercritical CO₂ methods were used for the experiments. Gelatin microparticles containing three different BSA amounts were incorporated into the porous scaffolds by using a surfactant. In vitro release profiles showed up to 90% protein loading efficiency. This novel method appears to be an effective approach for producing particles that can minimize protein loss during the loading process.

  5. Controlled-release microchips.

    Science.gov (United States)

    Sharma, Sadhana; Nijdam, A Jasper; Sinha, Piyush M; Walczak, Robbie J; Liu, Xuewu; Cheng, Mark M-C; Ferrari, Mauro

    2006-05-01

    Efficient drug delivery remains an important challenge in medicine: continuous release of therapeutic agents over extended time periods in accordance with a predetermined temporal profile; local delivery at a constant rate to the tumour microenvironment to overcome much of the systemic toxicity and to improve antitumour efficacy; improved ease of administration, and increasing patient compliance required are some of the unmet needs of the present drug delivery technology. Microfabrication technology has enabled the development of novel controlled-release microchips with capabilities not present in the current treatment modalities. In this review, the current status and future prospects of different types of controlled-release microchips are summarised and analysed with reference to microneedle-based microchips, as well as providing an in-depth focus on microreservoir-based and nanoporous microchips.

  6. Long-Term Controlled Protein Release from Poly(Ethylene Glycol) Hydrogels by Modulating Mesh Size and Degradation.

    Science.gov (United States)

    Tong, Xinming; Lee, Soah; Bararpour, Layla; Yang, Fan

    2015-12-01

    Poly(ethylene glycol) (PEG)-based hydrogels are popular biomaterials for protein delivery to guide desirable cellular fates and tissue repair. However, long-term protein release from PEG-based hydrogels remains challenging. Here, we report a PEG-based hydrogel platform for long term protein release, which allows efficient loading of proteins via physical entrapment. Tuning hydrogel degradation led to increase in hydrogel mesh size and gradual release of protein over 60 days of with retained bioactivity. Importantly, this platform does not require the chemical modification of loaded proteins, and may serve as a versatile tool for long-term delivery of a wide range of proteins for drug-delivery and tissue-engineering applications.

  7. Nanofibrous yet injectable polycaprolactone-collagen bone tissue scaffold with osteoprogenitor cells and controlled release of bone morphogenetic protein-2

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, Gayathri; Bialorucki, Callan [Department of Bioengineering, College of Engineering, University of Toledo, Toledo, OH 43606 (United States); Yildirim-Ayan, Eda, E-mail: eda.yildirimayan@utoledo.edu [Department of Bioengineering, College of Engineering, University of Toledo, Toledo, OH 43606 (United States); Department of Orthopaedic Surgery, University of Toledo Medical Center, Toledo, OH 43614 (United States)

    2015-06-01

    In this work, we developed a nanofibrous, yet injectable orthobiologic tissue scaffold that is capable of hosting osteoprogenitor cells and controlling kinetic release profile of the encapsulated pro-osteogenic factor without diminishing its bioactivity over 21 days. This innovative injectable scaffold was synthesized by incorporating electrospun and subsequently O{sub 2} plasma-functionalized polycaprolactone (PCL) nanofibers within the collagen type-I solution along with MC3T3-E1 cells (pre-osteoblasts) and bone morphogenetic protein-2 (BMP2). Through changing the PCL nanofiber concentration within the injectable scaffolds, we were able to tailor the mechanical strength, protein retention capacity, bioactivity preservation, and osteoinductive potential of the scaffolds. The nanofibrous internal structure of the scaffold allowed us to use a low dose of BMP2 (200 ng/ml) to achieve osteoblastic differentiation in in vitro culture. The osteogenesis capacity of the injectable scaffolds were evaluated though measuring MC3T3-E1 cell proliferation, ALP activity, matrix mineralization, and early- and late-osteoblast specific gene expression profiles over 21 days. The results demonstrated that the nanofibrous injectable scaffold provides not only an osteoinductive environment for osteoprogenitor cells to differentiate, but also a suitable biomechanical and biochemical environment to act as a reservoir for osteogenic factors with controlled release profile. - Highlights: • Injectable nanofibrous scaffold with osteoprogenitor cells and BMP2 was synthesized. • PCL nanofiber concentration within collagen scaffold affected the BMP2 retention and bioactivity. • Optimal PCL concentration was identified for mechanical stability, injectability, and osteogenic activity. • Scaffolds exhibited long-term osteoinductive capacity for bone repair and regeneration.

  8. Biocompatibility of a coacervate-based controlled release system for protein delivery to the injured spinal cord.

    Science.gov (United States)

    Rauck, Britta M; Novosat, Tabitha L; Oudega, Martin; Wang, Yadong

    2015-01-01

    The efficacy of protein-based therapies for treating injured nervous tissue is limited by the short half-life of free proteins in the body. Affinity-based biomaterial delivery systems provide sustained release of proteins, thereby extending the efficacy of such therapies. Here, we investigated the biocompatibility of a novel coacervate delivery system based on poly(ethylene argininylaspartate diglyceride) (PEAD) and heparin in the damaged spinal cord. We found that the presence of the [PEAD:heparin] coacervate did not affect the macrophage response, glial scarring or nervous tissue loss, which are hallmarks of spinal cord injury. Moreover, the density of axons, including serotonergic axons, at the injury site and the recovery of motor and sensorimotor function were comparable in rats with and without the coacervate. These results revealed the biocompatibility of our delivery system and supported its potential to deliver therapeutic proteins to the injured nervous system.

  9. 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

  10. Birth control - slow release methods

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/007555.htm Birth control - slow release methods To use the sharing features on this page, please enable JavaScript. Certain birth control methods contain man-made forms of hormones. These ...

  11. Examination of an aloe vera galacturonate polysaccharide capable of in situ gelation for the controlled release of protein therapeutics

    Science.gov (United States)

    McConaughy, Shawn David

    A therapeutic delivery platform has been investigated with the ultimate goal of designing a sustained protein release matrix utilizing an in-situ gelling, acidic polysaccharide derived from the Aloe vera plant. The Aloe vera polysaccharide (AvP) has been examined in order to determine how chemical composition, structure, molecular weight and solution behavior affect gelation and protein/peptide delivery. Correlations are drawn between structural characteristics and solution behavior in order to determine the impact of polymer conformation and solvation on gel formation under conditions designed to simulate nasal applications. Steady state and dynamic rheology, classic and dynamic light scattering, zeta potential, pulse field gradient nuclear magnetic resonance and fluorescence spectroscopy have been employed to gain insight into the effects of galacturonic acid content, degree of methylation, entanglement and ionic strength on both solution behavior and the hydrogel state which ultimately governs protein/peptide release. This dissertation is divided into two sections. In the first section, a series of Aloe vera polysaccharides (AvP), from the pectin family have been structurally characterized indicating high galacturonic acid (GalA) content, low degree of methylester substitution (DM), low numbers of rhamnose residues and high molecular weight with respect to pectins extracted from traditional sources. The behavior of AvP was examined utilizing dilute solution, low-shear rheological techniques for specific molecular weight samples at selected conditions of ionic strength. From these dilute aqueous solution studies, the Mark-Houwink-Sakurada (MHS) constants (K and alpha), persistence length (Lp) and inherent chain stiffness (B parameter) were determined, indicating an expanded random coil in aqueous salt solutions. The critical concentration for transition from dilute to concentrated solution, C e, was determined by measuring both the zero shear viscosity and

  12. Optogenetic control of ATP release

    Science.gov (United States)

    Lewis, Matthew A.; Joshi, Bipin; Gu, Ling; Feranchak, Andrew; Mohanty, Samarendra K.

    2013-03-01

    Controlled release of ATP can be used for understanding extracellular purinergic signaling. While coarse mechanical forces and hypotonic stimulation have been utilized in the past to initiate ATP release from cells, these methods are neither spatially accurate nor temporally precise. Further, these methods cannot be utilized in a highly effective cell-specific manner. To mitigate the uncertainties regarding cellular-specificity and spatio-temporal release of ATP, we herein demonstrate use of optogenetics for ATP release. ATP release in response to optogenetic stimulation was monitored by Luciferin-Luciferase assay (North American firefly, photinus pyralis) using luminometer as well as mesoscopic bioluminescence imaging. Our result demonstrates repetitive release of ATP subsequent to optogenetic stimulation. It is thus feasible that purinergic signaling can be directly detected via imaging if the stimulus can be confined to single cell or in a spatially-defined group of cells. This study opens up new avenue to interrogate the mechanisms of purinergic signaling.

  13. Actin related protein complex subunit 1b controls sperm release, barrier integrity and cell division during adult rat spermatogenesis.

    Science.gov (United States)

    Kumar, Anita; Dumasia, Kushaan; Deshpande, Sharvari; Gaonkar, Reshma; Balasinor, N H

    2016-08-01

    Actin remodeling is a vital process for signaling, movement and survival in all cells. In the testes, extensive actin reorganization occurs at spermatid-Sertoli cell junctions during sperm release (spermiation) and at inter Sertoli cell junctions during restructuring of the blood testis barrier (BTB). During spermiation, tubulobulbar complexes (TBCs), rich in branched actin networks, ensure recycling of spermatid-Sertoli cell junctional molecules. Similar recycling occurs during BTB restructuring around the same time as spermiation occurs. Actin related protein 2/3 complex is an essential actin nucleation and branching protein. One of its subunits, Arpc1b, was earlier found to be down-regulated in an estrogen-induced rat model of spermiation failure. Also, Arpc1b was found to be estrogen responsive through estrogen receptor beta in seminiferous tubule culture. Here, knockdown of Arpc1b by siRNA in adult rat testis led to defects in spermiation caused by failure in TBC formation. Knockdown also compromised BTB integrity and caused polarity defects of mature spermatids. Apart from these effects pertaining to Sertoli cells, Arpc1b reduction perturbed ability of germ cells to enter G2/M phase thus hindering cell division. In summary, Arpc1b, an estrogen responsive gene, is a regulator of spermiation, mature spermatid polarity, BTB integrity and cell division during adult spermatogenesis.

  14. The Rice Dynamin-Related Protein OsDRP1E Negatively Regulates Programmed Cell Death by Controlling the Release of Cytochrome c from Mitochondria

    Science.gov (United States)

    Zhou, Xueping

    2017-01-01

    Programmed cell death (PCD) mediated by mitochondrial processes has emerged as an important mechanism for plant development and responses to abiotic and biotic stresses. However, the role of translocation of cytochrome c from the mitochondria to the cytosol during PCD remains unclear. Here, we demonstrate that the rice dynamin-related protein 1E (OsDRP1E) negatively regulates PCD by controlling mitochondrial structure and cytochrome c release. We used a map-based cloning strategy to isolate OsDRP1E from the lesion mimic mutant dj-lm and confirmed that the E409V mutation in OsDRP1E causes spontaneous cell death in rice. Pathogen inoculation showed that dj-lm significantly enhances resistance to fungal and bacterial pathogens. Functional analysis of the E409V mutation showed that the mutant protein impairs OsDRP1E self-association and formation of a higher-order complex; this in turn reduces the GTPase activity of OsDRP1E. Furthermore, confocal microscopy showed that the E409V mutation impairs localization of OsDRP1E to the mitochondria. The E409V mutation significantly affects the morphogenesis of cristae in mitochondria and causes the abnormal release of cytochrome c from mitochondria into cytoplasm. Taken together, our results demonstrate that the mitochondria-localized protein OsDRP1E functions as a negative regulator of cytochrome c release and PCD in plants. PMID:28081268

  15. Radio-synthesized polyacrylamide hydrogels for proteins release

    Science.gov (United States)

    Ferraz, Caroline C.; Varca, Gustavo H. C.; Lopes, Patricia S.; Mathor, Monica B.; Lugão, Ademar B.

    2014-01-01

    The use of hydrogels for biomedical purposes has been extensively investigated. Pharmaceutical proteins correspond to highly active substances which may be applied for distinct purposes. This work concerns the development of radio-synthesized hydrogel for protein release, using papain and bovine serum albumin as model proteins. The polymer was solubilized (1% w/v) in water and lyophilized. The proteins were incorporated into the lyophilized polymer and the hydrogels were produced by simultaneous crosslinking and sterilization using γ-radiation under frozen conditions. The produced systems were characterized in terms of swelling degree, gel fraction, crosslinking density and evaluated according to protein release, bioactivity and cytotoxicity. The hydrogels developed presented different properties as a function of polymer concentration and the optimized results were found for the samples containing 4-5% (w/v) polyacrylamide. Protein release was controlled by the electrostatic affinity of acrylic moieties and proteins. This selection was based on the release of the proteins during the experiment period (up to 50 h), maintenance of enzyme activity and the nanostructure developed. The system was suitable for protein loading and release and according to the cytotoxic assay it was also adequate for biomedical purposes, however this method was not able to generate a matrix with controlled pore sizes.

  16. Modelling and simulations of controlled release fertilizer

    Science.gov (United States)

    Irfan, Sayed Ameenuddin; Razali, Radzuan; Shaari, Ku Zilati Ku; Mansor, Nurlidia

    2016-11-01

    The recent advancement in controlled release fertilizer has provided an alternative solution to the conventional urea, controlled release fertilizer has a good plant nutrient uptake they are environment friendly. To have an optimum plant intake of nutrients from controlled release fertilizer it is very essential to understand the release characteristics. A mathematical model is developed to predict the release characteristics from polymer coated granule. Numerical simulations are performed by varying the parameters radius of granule, soil water content and soil porosity to study their effect on fertilizer release. Understanding these parameters helps in the better design and improve the efficiency of controlled release fertilizer.

  17. Dual release of proteins from porous polymeric scaffolds

    NARCIS (Netherlands)

    Sohier, J.; Vlugt, T.J.H.; Cabrol, N.; Blitterswijk, van C.; Groot, de K.; Bezemer, J.M.

    2006-01-01

    To create porous scaffolds releasing in a controlled and independent fashion two different proteins, a novel approach based on protein-loaded polymeric coatings was evaluated. In this process, two water-in-oil emulsions are forced successively through a prefabricated scaffold to create coatings, con

  18. Mechanical properties, biological activity and protein controlled release by poly(vinyl alcohol)–bioglass/chitosan–collagen composite scaffolds: A bone tissue engineering applications

    Energy Technology Data Exchange (ETDEWEB)

    Pon-On, Weeraphat, E-mail: fsciwpp@ku.ac.th [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Charoenphandhu, Narattaphol; Teerapornpuntakit, Jarinthorn; Thongbunchoo, Jirawan; Krishnamra, Nateetip [Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University (Thailand); Department of Physiology, Faculty of Science, Mahidol University (Thailand); Tang, I-Ming [ThEP Center, Commission of Higher Education, 328 Si Ayutthaya Rd. (Thailand); Department of Materials Science, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand)

    2014-05-01

    In the present study, composite scaffolds made with different weight ratios (0.5:1, 1:1 and 2:1) of bioactive glass (15Ca:80Si:5P) (BG)/polyvinyl alcohol (PVA) (PVABG) and chitosan (Chi)/collagen (Col) (ChiCol) were prepared by three mechanical freeze–thaw followed by freeze-drying to obtain the porous scaffolds. The mechanical properties and the in vitro biocompatibility of the composite scaffolds to simulated body fluid (SBF) and to rat osteoblast-like UMR-106 cells were investigated. The results from the studies indicated that the porosity and compressive strength were controlled by the weight ratio of PVABG:ChiCol. The highest compressive modulus of the composites made was 214.64 MPa which was for the 1:1 weight ratio PVABG:ChiCol. Mineralization study in SBF showed the formation of apatite crystals on the PVABG:ChiCol surface after 7 days of incubation. In vitro cell availability and proliferation tests confirmed the osteoblast attachment and growth on the PVABG:ChiCol surface. MTT and ALP tests on the 1:1 weight ratio PVABG:ChiCol composite indicated that the UMR-106 cells were viable. Alkaline phosphatase activity was found to increase with increasing culturing time. In addition, we showed the potential of PVABG:ChiCol drug delivery through PBS solution studies. 81.14% of BSA loading had been achieved and controlled release for over four weeks was observed. Our results indicated that the PVABG:ChiCol composites, especially the 1:1 weight ratio composite exhibited significantly improved mechanical, mineral deposition, biological properties and controlled release. This made them potential candidates for bone tissue engineering applications. - Graphical abstract: Mechanical properties, biological activity and protein controlled release by poly(vinyl alcohol)–bioglass/chitosan–collagen composite scaffolds: A bone tissue engineering applications. - Highlights: • Preparation of PVABG:ChiCol hybrid composites and their bioactivities • Mechanical

  19. Microspheres based on biodegradable functionalized poly(alpha-hydroxy) acids for the controlled release of bioactive proteins and peptides

    NARCIS (Netherlands)

    Ghassemi, A.H.

    2011-01-01

    Pharmaceutical peptides/proteins have proven to be potent molecules for the treatment of a great variety of chronic and life threatening diseases. These molecules however demand a suitable formulation for their successful delivery. For formulation and delivery of such molecules the parenteral route

  20. Combinatorial Matrix Assisted Pulsed Laser Evaporation of a biodegradable polymer and fibronectin for protein immobilization and controlled release

    Energy Technology Data Exchange (ETDEWEB)

    Sima, F., E-mail: felix.sima@inflpr.ro [Lasers Department, National Institute for Lasers, Plasma and Radiation Physics, Măgurele (Romania); Axente, E.; Iordache, I.; Luculescu, C. [Lasers Department, National Institute for Lasers, Plasma and Radiation Physics, Măgurele (Romania); Gallet, O. [ERRMECE, Cergy-Pontoise University, Cergy-Pontoise (France); Anselme, K. [IS2M, CNRS UMR7361, Haute-Alsace University, Mulhouse (France); Mihailescu, I.N. [Lasers Department, National Institute for Lasers, Plasma and Radiation Physics, Măgurele (Romania)

    2014-07-01

    Defined protein quantities were embedded in situ in a biodegradable polymer coating during simultaneous laser vaporization of two targets. Fibronectin (FN) and poly-DL-lactide (PDLLA) were transferred and immobilized concomitantly by Combinatorial Matrix Assisted Pulsed Laser Evaporation onto solid substrates. The film surface with gradient of composition was characterized by optical, scanning electron microscopy and profilometry. Micrometric FN packages were visualized in the polymeric matrix by confocal microscopy. The composition of FN was investigated by FTIR and μFTIR analyses in a polymeric matrix with different thickness.

  1. Recent patents in flavor controlled release.

    Science.gov (United States)

    Feng, Tao; Xiao, Zuobing; Tian, Huaixiang

    2010-06-01

    In recent years, considerable effort has been directed toward the preparation of flavoring materials specifically, flavor materials have been sought that provide greater flavor intensity coupled with controlled flavor release for long periods of time. Here, some recent patents related to controlled flavor release are reviewed from the angle of its application field, its mechanism and its determination method. It is found that controlled flavor release often depends not only on materials' chemical and physical properties, such as melting point, solution properties and so on, but also on flavors' chemical and physical properties, such as diffusion capacity, its stability in different media etc. Meanwhile, flavor release is also controlled by an electric reducing device according to the flavor generation condition. It might be also known that flavor release rate could be determined by using a purge-and-trap/gas chromatographic procedure. In future, it's necessary to use mathematical model to study the kinetic behavior of controlled flavor release.

  2. Effect on cochlea function of guinea pig after controlled release recombinant human bone morphogenetic protein 2 transplanted into the middle ear

    Institute of Scientific and Technical Information of China (English)

    LI Xue-sheng; SUN Jian-jun; JIANG Wei; LIU Xiao

    2010-01-01

    Background The recombinant human bone morphogenetic protein 2 (rhBMP-2) has been used to induce osteogenesis in animals' middle ear and this technique is possible to be used to reconstruct the defects of ossicles. The side effects of the rhBMP-2 in middle ear should be observed before using in clinic. Thus we prepared the controlled release rhBMP-2 and implanted it into the acoustic bulla of guinea pigs. The effect on the cochlea was observed. Methods We prepared the acellular cancellous bone, accompanied with rhBMP-2. The material accompanied with rhBMP-2 was implanted into one acoustic bulla of the animal and the opposite side of the acoustic bulla was implanted with acellular cancellous bone without rhBMP-2. Totally 20 guinea pigs were undergone this procedure. After the operation, the auditory brainstem response (ABR) of the animals was tested according to the time sequence. Three months after the operation, the animals were sacrificed. The osteogenesis induced by rhBMP-2, the acoustic bulla and cochlea affected by rhBMP-2 were observed. The structures of hair cells were observed after silver nitrate staining. Results The animals were recovered soon after surgery. The hearing thresholds of the animals were declined slightly just after the surgery and come back completely after 3 months. Also, the bulla and cochlea were normal in shape. The osteogenesis occurred in the pore of the acellular cancellous bone with rhBMP-2. There was not any abnormal hyperplasia of bone in the bulla and cochlea. The articulation between the stapes and oval window was not merged. The shapes of the hair cells were normal and there was no obvious deletion of the hair cells compared with control group. Conclusions The controlled release rhBMP-2 transplanted into the middle ear could induce osteogenesis in the bulla of the animals. It did not affect the shape of the bulla and the hearing threshold of the animal, and did not induce the abnormal hyperplasia of bone in the bulla and might

  3. miR-346 controls release of TNF-α protein and stability of its mRNA in rheumatoid arthritis via tristetraprolin stabilization.

    Directory of Open Access Journals (Sweden)

    Noha Semaan

    Full Text Available TNF-α is a major cytokine implicated in rheumatoid arthritis. Its expression is regulated both at the transcriptional and posttranscriptional levels and recent data demonstrated that miRNAs are implicated in TNF-α response in macrophages. LPS-activated FLS isolated from RA patients express TNF-α mRNA but not the mature protein. This prompted us to look for miRNAs which could be implicated in this anti-inflammatory effect. Using a microarray, we found two miRNAs, miR-125b and miR-939 predicted to target the 3'-UTR of TNF-α mRNA, to be up-regulated in RA FLS in response to LPS, but their repression did not restore mature TNF-α expression in FLS. We showed previously that miR-346, which is upregulated in LPS-activated FLS, inhibited Btk expression that stabilized TNF-α mRNA. Blocking miR-346 reestablished TNF-α expression in activated FLS. Interestingly, transfection of miR-346 in LPS-activated THP-1 cells inhibited TNF-α secretion. We also demonstrated that TTP, a RNA binding protein which inhibited TNF-α synthesis, is overexpressed in activated FLS and that inhibition of miR-346 decreases its expression. Conversely, transfection of miR-346 in LPS-activated THP-1 cells increased TTP mRNA expression and inhibited TNF-α release. These results indicate that miR-346 controls TNF-α synthesis by regulating TTP expression.

  4. 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.

  5. 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 material

  6. 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

  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 material

  8. Biomagnetic of Apatite-Coated Cobalt Ferrite: A Core-Shell Particle for Protein Adsorption and pH-Controlled Release.

    Science.gov (United States)

    Tang, I-Ming; Krishnamra, Nateetip; Charoenphandhu, Narattaphol; Hoonsawat, Rassmidara; Pon-On, Weeraphat

    2011-12-01

    Magnetic nanoparticle composite with a cobalt ferrite (CoFe2O4, (CF)) core and an apatite (Ap) coating was synthesized using a biomineralization process in which a modified simulated body fluid (1.5SBF) solution is the source of the calcium phosphate for the apatite formation. The core-shell structure formed after the citric acid-stabilized cobalt ferrite (CFCA) particles were incubated in the 1.5 SBF solution for 1 week. The mean particle size of CFCA-Ap is about 750 nm. A saturation magnetization of 15.56 emug(-1) and a coercivity of 1808.5 Oe were observed for the CFCA-Ap obtained. Bovine serum albumin (BSA) was used as the model protein to study the adsorption and release of the proteins by the CFCA-Ap particles. The protein adsorption by the CFCA-Ap particles followed a more typical Freundlich than Langmuir adsorption isotherm. The BSA release as a function of time became less rapid as the CFCA-Ap particles were immersed in higher pH solution, thus indicating that the BSA release is dependent on the local pH.

  9. Biomagnetic of Apatite-Coated Cobalt Ferrite: A Core–Shell Particle for Protein Adsorption and pH-Controlled Release

    Science.gov (United States)

    2011-01-01

    Magnetic nanoparticle composite with a cobalt ferrite (CoFe2O4, (CF)) core and an apatite (Ap) coating was synthesized using a biomineralization process in which a modified simulated body fluid (1.5SBF) solution is the source of the calcium phosphate for the apatite formation. The core–shell structure formed after the citric acid–stabilized cobalt ferrite (CFCA) particles were incubated in the 1.5 SBF solution for 1 week. The mean particle size of CFCA-Ap is about 750 nm. A saturation magnetization of 15.56 emug-1 and a coercivity of 1808.5 Oe were observed for the CFCA-Ap obtained. Bovine serum albumin (BSA) was used as the model protein to study the adsorption and release of the proteins by the CFCA-Ap particles. The protein adsorption by the CFCA-Ap particles followed a more typical Freundlich than Langmuir adsorption isotherm. The BSA release as a function of time became less rapid as the CFCA-Ap particles were immersed in higher pH solution, thus indicating that the BSA release is dependent on the local pH. PMID:27502643

  10. Biomagnetic of Apatite-Coated Cobalt Ferrite: A Core–Shell Particle for Protein Adsorption and pH-Controlled Release

    Directory of Open Access Journals (Sweden)

    Krishnamra Nateetip

    2011-01-01

    Full Text Available Abstract Magnetic nanoparticle composite with a cobalt ferrite (CoFe2O4, (CF core and an apatite (Ap coating was synthesized using a biomineralization process in which a modified simulated body fluid (1.5SBF solution is the source of the calcium phosphate for the apatite formation. The core–shell structure formed after the citric acid–stabilized cobalt ferrite (CFCA particles were incubated in the 1.5 SBF solution for 1 week. The mean particle size of CFCA-Ap is about 750 nm. A saturation magnetization of 15.56 emug-1 and a coercivity of 1808.5 Oe were observed for the CFCA-Ap obtained. Bovine serum albumin (BSA was used as the model protein to study the adsorption and release of the proteins by the CFCA-Ap particles. The protein adsorption by the CFCA-Ap particles followed a more typical Freundlich than Langmuir adsorption isotherm. The BSA release as a function of time became less rapid as the CFCA-Ap particles were immersed in higher pH solution, thus indicating that the BSA release is dependent on the local pH.

  11. Release Control of Dye from Agar Ball

    OpenAIRE

    板屋, 智之; 山村, 俊貴; 唐澤, 有太朗

    2013-01-01

    Agar is a special product of Nagano prefecture. To utilize agar gel as adsorbing or releasing material of dyes or drugs, spherical agar gel “agar ball” was prepared by dropping aqueous agar solution into salad oil. And releasing behavior of a dye (rhodamine B) from agar ball was studied. The dye is released easily from agar ball, but the release can be controlled by hybiridazation of agar and galatin. In addition, it was found that agar ball could extract the dye from oil phase containing the...

  12. 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.

  13. 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.

  14. Mechanical properties, biological activity and protein controlled release by poly(vinyl alcohol)-bioglass/chitosan-collagen composite scaffolds: a bone tissue engineering applications.

    Science.gov (United States)

    Pon-On, Weeraphat; Charoenphandhu, Narattaphol; Teerapornpuntakit, Jarinthorn; Thongbunchoo, Jirawan; Krishnamra, Nateetip; Tang, I-Ming

    2014-05-01

    In the present study, composite scaffolds made with different weight ratios (0.5:1, 1:1 and 2:1) of bioactive glass (15Ca:80Si:5P) (BG)/polyvinyl alcohol (PVA) (PVABG) and chitosan (Chi)/collagen (Col) (ChiCol) were prepared by three mechanical freeze-thaw followed by freeze-drying to obtain the porous scaffolds. The mechanical properties and the in vitro biocompatibility of the composite scaffolds to simulated body fluid (SBF) and to rat osteoblast-like UMR-106 cells were investigated. The results from the studies indicated that the porosity and compressive strength were controlled by the weight ratio of PVABG:ChiCol. The highest compressive modulus of the composites made was 214.64 MPa which was for the 1:1 weight ratio PVABG:ChiCol. Mineralization study in SBF showed the formation of apatite crystals on the PVABG:ChiCol surface after 7 days of incubation. In vitro cell availability and proliferation tests confirmed the osteoblast attachment and growth on the PVABG:ChiCol surface. MTT and ALP tests on the 1:1 weight ratio PVABG:ChiCol composite indicated that the UMR-106 cells were viable. Alkaline phosphatase activity was found to increase with increasing culturing time. In addition, we showed the potential of PVABG:ChiCol drug delivery through PBS solution studies. 81.14% of BSA loading had been achieved and controlled release for over four weeks was observed. Our results indicated that the PVABG:ChiCol composites, especially the 1:1 weight ratio composite exhibited significantly improved mechanical, mineral deposition, biological properties and controlled release. This made them potential candidates for bone tissue engineering applications.

  15. Selective release from cultured mammalian cells of heat-shock (stress) proteins that resemble glia-axon transfer proteins.

    Science.gov (United States)

    Hightower, L E; Guidon, P T

    1989-02-01

    Cultured rat embryo cells were stimulated to rapidly release a small group of proteins that included several heat-shock proteins (hsp110, hsp71, hscp73) and nonmuscle actin. The extracellular proteins were analyzed by two-dimensional polyacrylamide gel electrophoresis. Heat-shocked cells released the same set of proteins as control cells with the addition of the stress-inducible hsp110 and hsp71. Release of these proteins was not blocked by either monensin or colchicine, inhibitors of the common secretory pathway. A small amount of the glucose-regulated protein grp78 was externalized by this pathway. The extracellular accumulation of these proteins was inhibited after they were synthesized in the presence of the lysine analogue aminoethyl cysteine. It is likely that the analogue-substituted proteins were misfolded and could not be released from cells, supporting our conclusion that a selective release mechanism is involved. Remarkably, actin and the squid heat-shock proteins homologous to rat hsp71 and hsp110 are also among a select group of proteins transferred from glial cells to the squid giant axon, where they have been implicated in neuronal stress responses (Tytell et al.: Brain Res., 363:161-164, 1986). Based in part on the similarities between these two sets of proteins, we hypothesized that these proteins were released from labile cortical regions of animal cells in response to perturbations of homeostasis in cells as evolutionarily distinct as cultured rat embryo cells and squid glial cells.

  16. Free boundary problems in controlled release pharmaceuticals: II. swelling-controlled release

    OpenAIRE

    Cohen, Donald S.; Erneux, Thomas

    1988-01-01

    A problem in controlled release pharmaceutical systems is formulated and studied. The device modeled is a polymer matrix containing an initially immobilized drug. The release of the drug is achieved by countercurrent diffusion through a penetrant solvent with the release rate being determined by the rate of diffusion of the solvent in the polymer. The mathematical theory yields a free boundary problem which is studied in various asymptotic regimes.

  17. Preventing and controlling accidental gas releases

    Science.gov (United States)

    Moskowitz, P. D.; Fthenakis, V. M.; Kalb, P. D.

    1988-07-01

    Toxic, flammable, and explosive gases may be used in photovoltaic cell research laboratories and in commercial manufacturing facilities. Accidental release of these materials can present hazards to life and property. Accidents can arise from a variety of mechanical and human related failures. These can occur from the time materials are received at the loading dock of the facility to the time treated gases are discharged to the atmosphere through a stack. Each type of initiating event may require a different control approach. These may range from the training and certification of plant workers charged with the handling of gas cylinder hookups to installation of emergency pollution control systems. Since engineering options for controlling released materials are limited, emphasis should be placed on administrative and engineering approaches for preventing such accidents. These are likely to be the most effective approaches for protecting life and property.

  18. Direct effects of TNF-α on local fuel metabolism and cytokine levels in the placebo-controlled, bilaterally infused human leg: increased insulin sensitivity, increased net protein breakdown, and increased IL-6 release.

    Science.gov (United States)

    Bach, Ermina; Nielsen, Roni R; Vendelbo, Mikkel H; Møller, Andreas B; Jessen, Niels; Buhl, Mads; K-Hafstrøm, Thomas; Holm, Lars; Pedersen, Steen B; Pilegaard, Henriette; Biensø, Rasmus S; Jørgensen, Jens O L; Møller, Niels

    2013-12-01

    Tumor necrosis factor-α (TNF-α) has widespread metabolic actions. Systemic TNF-α administration, however, generates a complex hormonal and metabolic response. Our study was designed to test whether regional, placebo-controlled TNF-α infusion directly affects insulin resistance and protein breakdown. We studied eight healthy volunteers once with bilateral femoral vein and artery catheters during a 3-h basal period and a 3-h hyperinsulinemic-euglycemic clamp. One artery was perfused with saline and one with TNF-α. During the clamp, TNF-α perfusion increased glucose arteriovenous differences (0.91 ± 0.17 vs. 0.74 ± 0.15 mmol/L, P = 0.012) and leg glucose uptake rates. Net phenylalanine release was increased by TNF-α perfusion with concomitant increases in appearance and disappearance rates. Free fatty acid kinetics was not affected by TNF-α, whereas interleukin-6 (IL-6) release increased. Insulin and protein signaling in muscle biopsies was not affected by TNF-α. TNF-α directly increased net muscle protein loss, which may contribute to cachexia and general protein loss during severe illness. The finding of increased insulin sensitivity, which could relate to IL-6, is of major clinical interest and may concurrently act to provide adequate tissue fuel supply and contribute to the occurrence of systemic hypoglycemia. This distinct metabolic feature places TNF-α among the rare insulin mimetics of human origin.

  19. Controlled release fertilizer workshop, 1991: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Scheib, R.M. [ed.

    1991-11-01

    Over the last 20 years the Tennessee Valley Authority`s National Fertilizer and Environmental Research Center (NFERC) has carried out a number of programs to develop controlled release fertilizers. They pioneered the development and commercialization of sulfur coated urea and conducted extensive research in an attempt to develop an economical synthesis for oxamide. In recent years there has developed an increasing interest in the environmental impact of fertilizers, particularly on the potential for ground water contamination by nitrate derived from fertilizer materials. In response to this interest NFERC`s Chemical Research Department organized a five member Controlled Release Fertilizer (CRF) Team to reassess the potential for controlled release materials in agriculture with a view to minimizing any adverse environmental impact and increasing the efficiency of nutrient utilization by the crop. This workshop was part of that reassessment program. The workshop goals were: To determine the present status of CRF research, production and use; to assess the future needs of CRF producers and consumers; and to promote communication and exchange of information. To accomplish these goals the team invited speakers from across` the United States representing academics, experimental station researchers, fertilizer producers, environmentalists, and marketing experts to present papers.

  20. Controlled release fertilizer workshop, 1991: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Scheib, R.M. (ed.)

    1991-11-01

    Over the last 20 years the Tennessee Valley Authority's National Fertilizer and Environmental Research Center (NFERC) has carried out a number of programs to develop controlled release fertilizers. They pioneered the development and commercialization of sulfur coated urea and conducted extensive research in an attempt to develop an economical synthesis for oxamide. In recent years there has developed an increasing interest in the environmental impact of fertilizers, particularly on the potential for ground water contamination by nitrate derived from fertilizer materials. In response to this interest NFERC's Chemical Research Department organized a five member Controlled Release Fertilizer (CRF) Team to reassess the potential for controlled release materials in agriculture with a view to minimizing any adverse environmental impact and increasing the efficiency of nutrient utilization by the crop. This workshop was part of that reassessment program. The workshop goals were: To determine the present status of CRF research, production and use; to assess the future needs of CRF producers and consumers; and to promote communication and exchange of information. To accomplish these goals the team invited speakers from across' the United States representing academics, experimental station researchers, fertilizer producers, environmentalists, and marketing experts to present papers.

  1. 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.

  2. Interaction of anesthetics with neurotransmitter release machinery proteins.

    Science.gov (United States)

    Xie, Zheng; McMillan, Kyle; Pike, Carolyn M; Cahill, Anne L; Herring, Bruce E; Wang, Qiang; Fox, Aaron P

    2013-02-01

    General anesthetics produce anesthesia by depressing central nervous system activity. Activation of inhibitory GABA(A) receptors plays a central role in the action of many clinically relevant general anesthetics. Even so, there is growing evidence that anesthetics can act at a presynaptic locus to inhibit neurotransmitter release. Our own data identified the neurotransmitter release machinery as a target for anesthetic action. In the present study, we sought to examine the site of anesthetic action more closely. Exocytosis was stimulated by directly elevating the intracellular Ca(2+) concentration at neurotransmitter release sites, thereby bypassing anesthetic effects on channels and receptors, allowing anesthetic effects on the neurotransmitter release machinery to be examined in isolation. Three different PC12 cell lines, which had the expression of different release machinery proteins stably suppressed by RNA interference, were used in these studies. Interestingly, there was still significant neurotransmitter release when these knockdown PC12 cells were stimulated. We have previously shown that etomidate, isoflurane, and propofol all inhibited the neurotransmitter release machinery in wild-type PC12 cells. In the present study, we show that knocking down synaptotagmin I completely prevented etomidate from inhibiting neurotransmitter release. Synaptotagmin I knockdown also diminished the inhibition produced by propofol and isoflurane, but the magnitude of the effect was not as large. Knockdown of SNAP-25 and SNAP-23 expression also changed the ability of these three anesthetics to inhibit neurotransmitter release. Our results suggest that general anesthetics inhibit the neurotransmitter release machinery by interacting with multiple SNARE and SNARE-associated proteins.

  3. 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

  4. Accelerating protein release from microparticles for regenerative medicine applications

    Energy Technology Data Exchange (ETDEWEB)

    White, Lisa J., E-mail: lisa.white@nottingham.ac.uk; Kirby, Giles T.S.; Cox, Helen C.; Qodratnama, Roozbeh; Qutachi, Omar; Rose, Felicity R.A.J.; Shakesheff, Kevin M.

    2013-07-01

    There is a need to control the spatio-temporal release kinetics of growth factors in order to mitigate current usage of high doses. A novel delivery system, capable of providing both structural support and controlled release kinetics, has been developed from PLGA microparticles. The inclusion of a hydrophilic PLGA–PEG–PLGA triblock copolymer altered release kinetics such that they were decoupled from polymer degradation. A quasi zero order release profile over four weeks was produced using 10% w/w PLGA–PEG–PLGA with 50:50 PLGA whereas complete and sustained release was achieved over ten days using 30% w/w PLGA–PEG–PLGA with 85:15 PLGA and over four days using 30% w/w PLGA–PEG–PLGA with 50:50 PLGA. These three formulations are promising candidates for delivery of growth factors such as BMP-2, PDGF and VEGF. Release profiles were also modified by mixing microparticles of two different formulations providing another route, not previously reported, for controlling release kinetics. This system provides customisable, localised and controlled delivery with adjustable release profiles, which will improve the efficacy and safety of recombinant growth factor delivery. Highlights: ► A new delivery system providing controlled release kinetics has been developed. ► Inclusion of hydrophilic PLGA–PEG–PLGA decoupled release kinetics from degradation. ► Using 10% triblock copolymer produced quasi zero order release over four weeks. ► Mixing microparticle formulations provided another route for controlling release. ► This system provides customisable, localised and controlled delivery of growth factors.

  5. Effects of Controlled Release Fertilizer on the Flag Leaves Senescence in Dry-land Wheat

    OpenAIRE

    Dandan Liu; Yan Shi

    2013-01-01

    In order to select a reasonable controlled release fertilizer application method to slow down the senescence of flag leaf in dry-land wheat. The effects of controlled release fertilizer on soluble protein content, MDA content, the Catalase (CAT) activity, the Superoxide Dismutase (SOD) activity on the flag leaves senescence in dry-land wheat had been studied in the open field with the variety wheat Jimai22. The results indicated that, the combination application of controlled release fertiliz...

  6. Effects of Controlled Release Fertilizer on the Flag Leaves Senescence in Dry-land Wheat

    OpenAIRE

    Dandan Liu; Yan Shi

    2013-01-01

    In order to select a reasonable controlled release fertilizer application method to slow down the senescence of flag leaf in dry-land wheat. The effects of controlled release fertilizer on soluble protein content, MDA content, the Catalase (CAT) activity, the Superoxide Dismutase (SOD) activity on the flag leaves senescence in dry-land wheat had been studied in the open field with the variety wheat Jimai22. The results indicated that, the combination application of controlled release fertiliz...

  7. The mechanism of protein release from triglyceride microspheres.

    Science.gov (United States)

    Zaky, A; Elbakry, A; Ehmer, A; Breunig, M; Goepferich, A

    2010-10-15

    The purpose of this study was to reveal factors that have an impact on the protein release kinetics from triglyceride microspheres prepared by spray congealing. We investigated the effect of protein particle size, morphology and distribution on protein release from microspheres by confocal laser scanning microscopy (CLSM)(.) The microspheres were loaded with three types of model particles made of FITC-labeled bovine serum albumin: freeze dried protein, spherical particles obtained by precipitation in the presence of PEG and micronized material. Investigation by light microscopy and laser light diffraction revealed that the freeze dried material consisted mainly of app. 29 μm elongated shaped particles. The precipitated BSA consisted mainly of 9.0 μm diameter spherically shaped particles while the micronized protein prepared by jet milling consisted of 4.9 μm sized rounded particles of high uniformity. Microspheres were embedded into a cold-curing resin and cut with a microtome. Subsequent investigation by CLSM revealed major differences of distribution of the polydisperse protein particles inside the microsphere sections depending on the type of BSA that was used. Particles of micronized and precipitated protein were distributed almost throughout the microsphere cross section. The protein distribution had a marked impact on the release kinetics in phosphate buffer. Large protein particles led to a considerably faster release than small ones. By staining the release medium we demonstrated that in all three cases there was a strong correlation between protein release and buffer intrusion. Copyright © 2010 Elsevier B.V. All rights reserved.

  8. A Responsive Battery with Controlled Energy Release.

    Science.gov (United States)

    Wang, Xiaopeng; Gao, Jian; Cheng, Zhihua; Chen, Nan; Qu, Liangti

    2016-11-14

    A new type of responsive battery with the fascinating feature of pressure perceptibility has been developed, which can spontaneously, timely and reliably control the power outputs (e.g., current and voltage) in response to pressure changes. The device design is based on the structure of the Zn-air battery, in which graphene-coated sponge serves as pressure-sensitive air cathode that endows the whole system with the capability of self-controlled energy release. The responsive batteries exhibit superior battery performance with high open-circuit voltage (1.3 V), and competitive areal capacity of 1.25 mAh cm(-2) . This work presents an important move towards next-generation intelligent energy storage devices with energy management function. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Normal-release and controlled-release oxycodone: pharmacokinetics, pharmacodynamics, and controversy.

    Science.gov (United States)

    Davis, Mellar P; Varga, James; Dickerson, Duke; Walsh, Declan; LeGrand, Susan B; Lagman, Ruth

    2003-02-01

    Oxycodone has become one of the most popular opioids in the United States. It is superior to morphine in oral absorption and bioavailability, and similar in terms of protein binding and lipophilicity. Gender more than age influences oxycodone elimination. Unlike morphine, oxycodone is metabolized by the cytochrome isoenzyme CYP2D6, which is severely impaired by liver dysfunction. Controlled-release (CR) oxycodone has become one of the most frequently utilized sustained-release opioids in the United States. Both its analgesic benefits and its side effects are similar to those of CR morphine. CR oxycodone is similar to morphine and other opioids in its abuse potential. Deaths attributable to oxycodone are usually associated with polysubstance abuse in which oxycodone is combined with psychostimulants, other opioids, benzodiazepines or alcohol. Oxycodone's kappa receptor binding has little role in abuse or addiction. The cost of CR oxycodone is prohibitive for most American hospices.

  10. Release of proteins via ion exchange from albumin-heparin microspheres

    NARCIS (Netherlands)

    Kwon, Glen S.; Bae, You Han; Cremers, Harry; Feijen, Jan; Kim, Sung Wan

    1992-01-01

    Albumin-heparin and albumin microspheres were prepared as ion exchange gels for the controlled release of positively charged polypeptides and proteins. The adsorption isotherms of chicken egg and human lysozyme, as model proteins, on microspheres were obtained. An adsorption isotherm of chicken egg

  11. Mechanism of controlled release kinetics from medical devices

    Directory of Open Access Journals (Sweden)

    A. Raval

    2010-06-01

    Full Text Available Utilization of biodegradable polymers for controlled drug delivery has gained immense attention in the pharmaceutical and medical device industry to administer various drugs, proteins and other bio-molecules both systematically and locally to cure several diseases. The efficacy and toxicity of this local therapeutics depends upon drug release kinetics, which will further decide drug deposition, distribution, and retention at the target site. Drug Eluting Stent (DES presently possesses clinical importance as an alternative to Coronary Artery Bypass Grafting due to the ease of the procedure and comparable safety and efficacy. Many models have been developed to describe the drug delivery from polymeric carriers based on the different mechanisms which control the release phenomenon from DES. Advanced characterization techniques facilitate an understanding of the complexities behind design and related drug release behavior of drug eluting stents, which aids in the development of improved future drug eluting systems. This review discusses different drug release mechanisms, engineering principles, mathematical models and current trends that are proposed for drug-polymer coated medical devices such as cardiovascular stents and different analytical methods currently utilized to probe diverse characteristics of drug eluting devices.

  12. Protein antifouling and fouling-release in perfluoropolyether surfaces

    Science.gov (United States)

    Molena, Elena; Credi, Caterina; De Marco, Carmela; Levi, Marinella; Turri, Stefano; Simeone, Giovanni

    2014-08-01

    Perfluoropolyether polymers have been described as high performance fouling-release materials for marine coatings. Moreover, they have a good potential to be exploited in the biomedical field too. In this article several perfuoropolyether photopolymers were characterized in terms of surface and mechanical properties outlining the relationship between these properties and the polymer molecular structure. In particular the anti-fouling and fouling-release performances, evaluated using Bovine Serum Albumin as testing protein, was correlated to other material properties, like a parameter considering both surface tension components γ and elastic modulus E. A good correlation between the anti-fouling/fouling-release of perfluoropolyethers and (E*γpolar)1/2 can actually be established. Our results show that perfluoropolyether photopolymers are good protein anti-fouling/fouling-release materials.

  13. Preparation and controlled release effect of soybean protein/multicarboxylic acids modified cotton fabric%大豆蛋白/复合羧酸改性棉织物的制备及其缓释效果

    Institute of Scientific and Technical Information of China (English)

    许云辉; 王晓明; 张晓丽

    2013-01-01

    To develop an eco-friendly and multifunctional cotton fabric,the modification treatment of cotton fabric was undertaken using citric acid,maleic acid and soybean protein so that the chemical bonding between soybean protein and cotton fabric was formed through the bridging function of multicarboxylic acids.Effects of treating conditions on the weighting percentage of cotton fabric were analyzed and the optimized process parameters were obtained.The characterization of infrared spectra and X-ray photoelectron spectrometry showed that the esterification crosslinking occurred between multicarboxylic acids and macromolecules of cotton fiber according to ring-anhydride mechanism,while the soybean protein was adhered to the cotton fabric with amido bond by the bridging function of multicarboxylic acids.The breaking strength of soybean protein modified cotton fabric slightly decreased,whereas the anti-ultraviolet-ray property of the modified cotton fabric after cactus extract treatment improved remarkably.Furthermore,the drug controlled release test showed that when soybean protein modified cotton fabric was used as the carrier for cactus extract,good controlled release effect was achieved.%为开发生态多功能棉织物,采用柠檬酸、马来酸、大豆蛋白对棉织物进行改性处理,通过复合羧酸的桥联作用,使大豆蛋白与棉织物形成化学键交联结合,研究处理条件对棉织物增重率的影响,并得出最优工艺参数.红外光谱和光电子能谱测试表明,复合羧酸与棉纤维大分子按环酐机制产生酯化交联,大豆蛋白借助复合羧酸的桥联作用以酰胺键共价结合在棉织物上.大豆蛋白改性棉织物的断裂强力略有下降,再经仙人掌提取物处理的大豆蛋白改性棉织物抗紫外线性能明显提高,药物缓释试验显示,大豆蛋白改性棉织物作为药物载体对仙人掌提取物的缓释效果良好.

  14. In Vitro Cytotoxicity and Protein Drug Release Properties of Chitosan/Heparin Microspheres

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Chitosan/heparin microspheres were prepared using the water-in-oil emulsification solvent evaporation technique. The microsphere diameters were controlled by selecting the fabrication process parameters. Scanning electron micrographs showed that the chitosan/heparin microspheres were regular and the surface morphology was smooth. Fourier transform infrared showed that the chitosan amino groups reacted with heparin carboxylic groups to form acylamides in the microspheres. Analysis of the microsphere cytotoxicity showed that they had no cytotoxic effect and behaved very similar to the negative control (polystyrene).To analyze the protein drug release profiles of the microspheres, bovine serum albumin was loaded as a model drug into the microspheres and released in vitro. Marked retardation was observed in the BSA release profiles. The results show that chitosan/heparin microspheres may provide a useful controlled release protein drug system for used in pharmaceutics.

  15. TIM-family proteins inhibit HIV-1 release.

    Science.gov (United States)

    Li, Minghua; Ablan, Sherimay D; Miao, Chunhui; Zheng, Yi-Min; Fuller, Matthew S; Rennert, Paul D; Maury, Wendy; Johnson, Marc C; Freed, Eric O; Liu, Shan-Lu

    2014-09-02

    Accumulating evidence indicates that T-cell immunoglobulin (Ig) and mucin domain (TIM) proteins play critical roles in viral infections. Herein, we report that the TIM-family proteins strongly inhibit HIV-1 release, resulting in diminished viral production and replication. Expression of TIM-1 causes HIV-1 Gag and mature viral particles to accumulate on the plasma membrane. Mutation of the phosphatidylserine (PS) binding sites of TIM-1 abolishes its ability to block HIV-1 release. TIM-1, but to a much lesser extent PS-binding deficient mutants, induces PS flipping onto the cell surface; TIM-1 is also found to be incorporated into HIV-1 virions. Importantly, TIM-1 inhibits HIV-1 replication in CD4-positive Jurkat cells, despite its capability of up-regulating CD4 and promoting HIV-1 entry. In addition to TIM-1, TIM-3 and TIM-4 also block the release of HIV-1, as well as that of murine leukemia virus (MLV) and Ebola virus (EBOV); knockdown of TIM-3 in differentiated monocyte-derived macrophages (MDMs) enhances HIV-1 production. The inhibitory effects of TIM-family proteins on virus release are extended to other PS receptors, such as Axl and RAGE. Overall, our study uncovers a novel ability of TIM-family proteins to block the release of HIV-1 and other viruses by interaction with virion- and cell-associated PS. Our work provides new insights into a virus-cell interaction that is mediated by TIMs and PS receptors.

  16. Control of noradrenaline release from hippocampal synaptosomes

    Energy Technology Data Exchange (ETDEWEB)

    West, D.P.; Fillenz, M.

    1981-10-01

    Potassium-evoked tritiated noradrenaline (NA) release from hippocampal synaptosomes was measured with a superfusion method. A single 2-min high-K+ pulse released 39% of the vesicular NA by a Ca2+-dependent mechanism: the Ca2+-independent release was negligible. After changing the vesicular NA store size by pretreating rats with either alpha-methyl-para-tyrosine, 500 mg/kg, or tranylcypromine, 10 mg/kg, a single K+ pulse released a constant percentage of the vesicular NA. With two K+ pulses, however, there was a reduction in the percentage of vesicular NA released in response to the second pulse.

  17. Microstructured dextran hydrogels for burst-free sustained release of PEGylated protein drugs.

    Science.gov (United States)

    Bae, Ki Hyun; Lee, Fan; Xu, Keming; Keng, Choong Tat; Tan, Sue Yee; Tan, Yee Joo; Chen, Qingfeng; Kurisawa, Motoichi

    2015-09-01

    Hydrogels have gained significant attention as ideal delivery vehicles for protein drugs. However, the use of hydrogels for protein delivery has been restricted because their porous structures inevitably cause a premature leakage of encapsulated proteins. Here, we report a simple yet effective approach to regulate the protein release kinetics of hydrogels through the creation of microstructures, which serve as a reservoir, releasing their payloads in a controlled manner. Microstructured dextran hydrogels enable burst-free sustained release of PEGylated interferon over 3 months without compromising its bioactivity. These hydrogels substantially extend the circulation half-life of PEGylated interferon, allowing for less frequent dosing in a humanized mouse model of hepatitis C. The present approach opens up possibilities for the development of sustained protein delivery systems for a broad range of pharmaceutical and biomedical applications.

  18. Interaction between protein kinase C and protein kinase A can modulate transmitter release at the rat neuromuscular synapse.

    Science.gov (United States)

    Santafé, M M; Garcia, N; Lanuza, M A; Tomàs, M; Tomàs, J

    2009-02-15

    We used intracellular recording to investigate the functional interaction between protein kinase C (PKC) and protein kinase A (PKA) signal transduction cascades in the control of transmitter release in the neuromuscular synapses from adult rats. Our results indicate that: 1) PKA and PKC are independently involved in asynchronous release. 2) Evoked acetylcholine (ACh) release is enhanced with the PKA agonist Sp-8-BrcAMP and the PKC agonist phorbol ester (PMA). 3) PKA has a constitutive role in promoting a component of normal evoked transmitter release because, when the kinase is inhibited with H-89, the release diminishes. However, the PKC inhibitor calphostin C (CaC) does not affect ACh release. 4) PKA regulates neurotransmission without PKC involvement because, after PMA or CaC modulation of the PKC activity, coupling to the ACh release of PKA can normally be stimulated with Sp-8-BrcAMP or inhibited with H-89. 5) After PKA inhibition with H-89, PKC stimulation with PMA (or inhibition with CaC) does not lead to any change in evoked ACh release. However, in PKA-stimulated preparations with Sp-8-BrcAMP, PKC becomes tonically active, thus potentiating a component of release that can now be blocked with CaC. In normal conditions, therefore, PKA was able to modulate ACh release independently of PKC activity, whereas PKA stimulation caused the PKC coupling to evoked release. In contrast, PKA inhibition prevent PKC stimulation (with the phorbol ester) and coupling to ACh output. There was therefore some dependence of PKC on PKA activity in the fine control of the neuromuscular synaptic functionalism and ACh release.

  19. Biological control of weeds release sites : Kulm Wetland Management District

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Table of release sites of insects for biological control of invasive plants at Kulm Wetland Management District (WMD). Insects were released on Kulm WMD to...

  20. Triggered drug release from dynamic microspheres via a protein conformational change.

    Science.gov (United States)

    King, William J; Pytel, Nicholas J; Ng, Kelvin; Murphy, William L

    2010-06-11

    In this study we formed and characterized dynamic hydrogel microspheres in which a protein conformational change was used to control microsphere volume changes and the release of an encapsulated drug. In particular, a specific biochemical ligand, trifluoperazine, induced calmodulin's nanometer scale conformation change, which translated to a 48.7% microsphere volume decrease. This specific, ligand-induced volume change triggered the release of a model drug, vascular endothelial growth factor (VEGF), at pre-determined times. After release from the microspheres, 85.6 +/- 10.5% of VEGF was in its native conformation. Taken together, these results suggest that protein conformational change could serve as a useful mechanism to control drug release from dynamic hydrogels.

  1. Graphene as a photothermal switch for controlled drug release

    Science.gov (United States)

    Matteini, Paolo; Tatini, Francesca; Cavigli, Lucia; Ottaviano, Stefania; Ghini, Giacomo; Pini, Roberto

    2014-06-01

    Graphene has recently emerged as a novel material in the biomedical field owing to its optical properties, biocompatibility, large specific surface area and low cost. In this paper, we provide the first demonstration of the possibility of using light to remotely trigger the release of drugs from graphene in a highly controlled manner. Different drugs including chemotherapeutics and proteins are firmly adsorbed onto reduced graphene oxide (rGO) nanosheets dispersed in a biopolymer film and then released by individual millisecond-long light pulses generated by a near infrared (NIR) laser. Here graphene plays the dual role of a versatile substrate for temporary storage of drugs and an effective transducer of NIR-light into heat. Drug release appears to be narrowly confined within the size of the laser spot under noninvasive conditions and can be precisely dosed depending on the number of pulses. The approach proposed paves the way for tailor-made pharmacological treatments of chronic diseases, including cancer, anaemia and diabetes.Graphene has recently emerged as a novel material in the biomedical field owing to its optical properties, biocompatibility, large specific surface area and low cost. In this paper, we provide the first demonstration of the possibility of using light to remotely trigger the release of drugs from graphene in a highly controlled manner. Different drugs including chemotherapeutics and proteins are firmly adsorbed onto reduced graphene oxide (rGO) nanosheets dispersed in a biopolymer film and then released by individual millisecond-long light pulses generated by a near infrared (NIR) laser. Here graphene plays the dual role of a versatile substrate for temporary storage of drugs and an effective transducer of NIR-light into heat. Drug release appears to be narrowly confined within the size of the laser spot under noninvasive conditions and can be precisely dosed depending on the number of pulses. The approach proposed paves the way for tailor

  2. Survey of bacterial proteins released in cheese: a proteomic approach.

    Science.gov (United States)

    Gagnaire, Valérie; Piot, Michel; Camier, Bénédicte; Vissers, Johannes P C; Jan, Gwénaël; Léonil, Joëlle

    2004-07-15

    During the ripening of Emmental cheese, the bacterial ecosystem confers its organoleptic characteristics to the evolving curd both by the action of the living cells, and through the release of numerous proteins, including various types of enzymes into the cheese when the cells lyse. In Emmental cheese these proteins can be released from thermophilic lactic acid bacteria used as starters like Lactobacillus helveticus, Lb delbruecki subsp. lactis and Streptococcus salivarius subsp. thermophilus and ripening bacteria such as Propionibacterium freudenreichii. The aim of this study was to obtain a proteomic view of the different groups of proteins within the cheese using proteomic tools to create a reference map. A methodology was therefore developed to reduce the complexity of cheese matrix prior to 2D-PAGE analysis. The aqueous phase of cheese was prefractionated by size exclusion chromatography, bacterial and milk proteins were separated and subsequently characterised by mass spectrometry, prior to peptide mass fingerprint and sequence homology database search. Five functional groups of proteins were identified involved in: (i) proteolysis, (ii) glycolysis, (iii) stress response, (iv) DNA and RNA repair and (v) oxidoreduction. The results revealed stress responses triggered by thermophilic lactic acid bacteria and Propionibacterium strains at the end of ripening. Information was also obtained regarding the origin and nature of the peptidases released into the cheese, thus providing a greater understanding of casein degradation mechanisms during ripening. Different peptidases arose from St thermophilus and Lb helveticus, suggesting that streptococci are involved in peptide degradation in addition to the proteolytic activity of lactobacilli.

  3. Bacterial Ice Crystal Controlling Proteins

    Directory of Open Access Journals (Sweden)

    Janet S. H. Lorv

    2014-01-01

    Full Text Available Across the world, many ice active bacteria utilize ice crystal controlling proteins for aid in freezing tolerance at subzero temperatures. Ice crystal controlling proteins include both antifreeze and ice nucleation proteins. Antifreeze proteins minimize freezing damage by inhibiting growth of large ice crystals, while ice nucleation proteins induce formation of embryonic ice crystals. Although both protein classes have differing functions, these proteins use the same ice binding mechanisms. Rather than direct binding, it is probable that these protein classes create an ice surface prior to ice crystal surface adsorption. Function is differentiated by molecular size of the protein. This paper reviews the similar and different aspects of bacterial antifreeze and ice nucleation proteins, the role of these proteins in freezing tolerance, prevalence of these proteins in psychrophiles, and current mechanisms of protein-ice interactions.

  4. Molecularly imprinted nanotubes for enantioselective drug delivery and controlled release.

    Science.gov (United States)

    Yin, Junfa; Cui, Yue; Yang, Gengliang; Wang, Hailin

    2010-11-07

    Molecularly imprinted nanotubes for enantioselective drug delivery and controlled release are fabricated by the combination of template synthesis and ATRP grafting. The release of R-propranolol from the imprinted nanotubes in rats is restricted while the release of pharmacologically active S-enantiomer is greatly promoted.

  5. Analytical solution of diffusion model for nutrient release from controlled release fertilizer

    Science.gov (United States)

    Ameenuddin Irfan, Sayed; Razali, Radzuan; KuShaari, KuZilati; Mansor, Nurlidia; Azeem, Babar

    2017-09-01

    An analytical method has been developed to solve the initial value problem which arises from Fick’s diffusion equation encountered in the modelling of the Controlled Release Fertilizers. The proposed analytical solution is developed using the modified Adomian decomposition method. This method does not require the discretization method, reliability and efficiency of this method is more and it also reduces the calculation time. The model has predicted the effect of granule radius and diffusion coefficient on the nutrient release and total release time of Controlled Release Fertilizer. Model has predicted that increase in the radius of granule reduces the release and vice versa in case of diffusion coefficient. Detailed understanding of these parameters helps in improved designing of Controlled Release Fertilizer.

  6. Controllability in protein interaction networks.

    Science.gov (United States)

    Wuchty, Stefan

    2014-05-13

    Recently, the focus of network research shifted to network controllability, prompting us to determine proteins that are important for the control of the underlying interaction webs. In particular, we determined minimum dominating sets of proteins (MDSets) in human and yeast protein interaction networks. Such groups of proteins were defined as optimized subsets where each non-MDSet protein can be reached by an interaction from an MDSet protein. Notably, we found that MDSet proteins were enriched with essential, cancer-related, and virus-targeted genes. Their central position allowed MDSet proteins to connect protein complexes and to have a higher impact on network resilience than hub proteins. As for their involvement in regulatory functions, MDSet proteins were enriched with transcription factors and protein kinases and were significantly involved in bottleneck interactions, regulatory links, phosphorylation events, and genetic interactions.

  7. [Nutrient release characteristics and use efficiency of slow- and controlled release fertilizers].

    Science.gov (United States)

    Duan, Lu-Lu; Zhang, Min; Liu, Gang; Shang, Zhao-Cong; Yang, Yi

    2009-05-01

    Water extraction method and soil incubation method were used to study the nutrient release characteristics of four slow- and controlled release fertilizers (CRF1, CRF2, SCU, and IBDU), and pot experiment was conducted to assess the effects of the release characteristics on the nutrient requirements of canola (Brassica napus L.). The nutrient release curves of test fertilizers in water were S pattern for CRF1 and CRF2, burst pattern for SCU, and reverse L pattern for IBDU. The nutrient release characteristics of the four fertilizers in water and in soil all fitted binomial equations, suggesting that there existed some similarities in the nutrient release in the two media. The nutrient uptake and biomass of canola plants treated with CRF1 and CRF2 were significantly higher than those treated with SCU and IBDU, and CRF2 had the greatest effect. The nutrient release curves of CRF1 and CRF2 accorded more closely with the nutrient requirements of canola.

  8. Hot Melt Extrusion for Sustained Protein Release: Matrix Erosion and In Vitro Release of PLGA-Based Implants.

    Science.gov (United States)

    Cossé, Anne; König, Corinna; Lamprecht, Alf; Wagner, Karl G

    2017-01-01

    The design of biodegradable implants for sustained release of proteins is a complex challenge optimizing protein polymer interaction in combination with a mini-scale process which is predictive for production. The process of hot melt extrusion (HME) was therefore conducted on 5- and 9-mm mini-scale twin screw extruders. Poly(lactic-co-glycolic acid) (PLGA) implants were characterized for their erosion properties and the in vitro release of the embedded protein (bovine serum albumin, BSA). The release of acidic monomers as well as other parameters (pH value, mass loss) during 16 weeks indicated a delayed onset of matrix erosion in week 3. BSA-loaded implants released 17.0% glycolic and 5.9% lactic acid after a 2-week lag time. Following a low burst release (3.7% BSA), sustained protein release started in week 4. Storage under stress conditions (30°C, 75% rH) revealed a shift of erosion onset of 1 week (BSA-loaded implants: 26.9% glycolic and 9.3% lactic acid). Coherent with the changed erosion profiles, an influence on the protein release was observed. Confocal laser scanning and Raman microscopy showed a homogenous protein distribution throughout the matrix after extrusion and during release studies. Raman spectra indicated a conformational change of the protein structure which could be one reason for incomplete protein release. The study underlined the suitability of the HME process to obtain a solid dispersion of protein inside a polymeric matrix providing sustained protein release. However, the incomplete protein release and the impact by storage conditions require thorough characterization and understanding of erosion and release mechanisms.

  9. Environmental Release Prevention and Control Plan

    Energy Technology Data Exchange (ETDEWEB)

    Mamatey, A.; Arnett, M.

    1997-10-01

    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.

  10. 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.

  11. 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.

  12. 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.

  13. Chitosan nanoparticles crosslinked by glycidoxypropyltrimethoxysilane for pH triggered release of protein

    Institute of Scientific and Technical Information of China (English)

    Ai Wu Pan; Bei Bei Wu; Jian Min Wu

    2009-01-01

    pH-responsive-chitosan nanoparticles for the control release of protein drug were prepared by combining two-step crosslinking method, in which chitosan was subsequently crosslinked by sodium tripolyphosphate (TPP) and glycidoxypropyltrimethoxysilane (GPTMS). Compared with TPP crosslinked chitosan particles, the two-step crosslinked nanoparticles were not only pH-responsive but also more stable in wide pH range. Fluorescein isothiocyanate (FITC) labeled anti-human-IgG antibody was used as a model protein drug for evaluating the control release profile of the nano-carrier. The amount of released antibody increased from 5.6% to 50% when the pH of solution shifted from 7.4 m 6.0. The results suggest the possible application of the nanoparticles as pH-responsive drug delivery materials.

  14. A retrospective mathematical analysis of controlled release design and experimentation.

    Science.gov (United States)

    Rothstein, Sam N; Kay, Jennifer E; Schopfer, Francisco J; Freeman, Bruce A; Little, Steven R

    2012-11-01

    The development and performance evaluation of new biodegradable polymer controlled release formulations relies on successful interpretation and evaluation of in vitro release data. However, depending upon the extent of empirical characterization, release data may be open to more than one qualitative interpretation. In this work, a predictive model for release from degradable polymer matrices was applied to a number of published release data in order to extend the characterization of release behavior. Where possible, the model was also used to interpolate and extrapolate upon collected released data to clarify the overall duration of release and also kinetics of release between widely spaced data points. In each case examined, mathematical predictions of release coincide well with experimental results, offering a more definitive description of each formulation's performance than was previously available. This information may prove particularly helpful in the design of future studies, such as when calculating proper dosing levels or determining experimental end points in order to more comprehensively evaluate a controlled release system's performance.

  15. Gelatin methacrylate microspheres for controlled growth factor release.

    Science.gov (United States)

    Nguyen, Anh H; McKinney, Jay; Miller, Tobias; Bongiorno, Tom; McDevitt, Todd C

    2015-02-01

    Gelatin has been commonly used as a delivery vehicle for various biomolecules for tissue engineering and regenerative medicine applications due to its simple fabrication methods, inherent electrostatic binding properties, and proteolytic degradability. Compared to traditional chemical cross-linking methods, such as the use of glutaraldehyde (GA), methacrylate modification of gelatin offers an alternative method to better control the extent of hydrogel cross-linking. Here we examined the physical properties and growth factor delivery of gelatin methacrylate (GMA) microparticles (MPs) formulated with a wide range of different cross-linking densities (15-90%). Less methacrylated MPs had decreased elastic moduli and larger mesh sizes compared to GA MPs, with increasing methacrylation correlating to greater moduli and smaller mesh sizes. As expected, an inverse correlation between microparticle cross-linking density and degradation was observed, with the lowest cross-linked GMA MPs degrading at the fastest rate, comparable to GA MPs. Interestingly, GMA MPs at lower cross-linking densities could be loaded with up to a 10-fold higher relative amount of growth factor than conventional GA cross-linked MPs, despite the GA MPs having an order of magnitude greater gelatin content. Moreover, a reduced GMA cross-linking density resulted in more complete release of bone morphogenic protein 4 and basic fibroblast growth factor and accelerated release rate with collagenase treatment. These studies demonstrate that GMA MPs provide a more flexible platform for growth factor delivery by enhancing the relative binding capacity and permitting proteolytic degradation tunability, thereby offering a more potent controlled release system for growth factor delivery.

  16. Electrospinning nanofibers for controlled drug release

    Science.gov (United States)

    Banik, Indrani

    Electrospinning is the most widely studied technique for the synthesis of nanofibers. Electrospinning is considered as one of the technologies that can produce nanosized drugs incorporated in polymeric nanofibers. In vitro and in vivo studies have demonstrated that the release rates of drugs from these nanofiber formulations are enhanced compared to those from original drug substance. This technology has the potential for enhancing the oral delivery of poorly soluble drugs. The electrospun mats were made using Polycaprolactone/PCL, Poly(DL-lactide)/PDL 05 and Poly(DL-lactide-co-glycolide)/PLGA. The drugs incorporated in the electrospun fibers were 5-Fluorouracil and Rapamycin. The evidence of the drugs being embedded in the polymers was obtained by scanning electron microscopy (SEM), Raman and infrared spectroscopy. The release of 5-Fluorouracil and Rapamycin were followed by UV-VIS spectroscopy.

  17. Application of advanced polymeric materials for controlled release pesticides

    Science.gov (United States)

    Rahim, M.; Hakim, M. R.; Haris, H. M.

    2016-08-01

    The objective of this work was to study the capability of advanced polymeric material constituted by chitosan and natural rubber matrices for controlled release of pesticides (1-hydroxynaphthalene and 2-hydroxynaphthalene) in aqueous solution. The released amount of pesticides was measured spectrophotometrically from the absorbance spectra applying a standardized curve. The release of the pesticides was studied into refreshing and non-refreshing neutral aqueous media. Interestingly, formulation successfully indicated a consistent, controlled and prolonged release of pesticides over a period of 35 days.

  18. Controlled-release Properties of Microencapsulated Disperse Dyes

    Institute of Scientific and Technical Information of China (English)

    LUO Yan; LI Chun-yan; CHEN Shui-lin

    2002-01-01

    Some disperse dyes were microencapsulated by means of in- situ polymerization. These microencapsulated disperse dyes was extracted respectively by ethanol under certain conditions. The controlled-release properties of disperse dyes through the shell of microcapsules were measured by spectrophotometer. According to the results, it was drawn that the type of disperse dyes, the auxiliaries contained in disperse dyes, the quantity of system controlling medium used and the core/shell ratio of microcapsules play important roles in controlling the release properties of microcapsules. The different controlled- release properties of microcapsules, which were prepared under given conditions, however, would in turn influence the performance of microcapsules in multiple-transfer printing.

  19. Optimal Release Control of Companion Satellite System Using Electromagnetic Forces

    Institute of Scientific and Technical Information of China (English)

    Zengwen Xu,Peng Shi; Yushan Zhao∗

    2015-01-01

    Electromagnetic forces generated by the inter⁃action of component satellites can be used to release companion satellites. Optimal release trajectories for companion satellite system using inter⁃electromagnetic forces were investigated. Firstly, nonlinear relative motion dynamic equations of a two⁃craft electromagnetic companion satellite system were derived in spatial polar coordinates. Then principles of electromagnetic satellite formation flying were introduced. Secondly, the characteristics of the electromagnetic companion satellites release were analyzed and optimal release trajectories of companion satellites using electromagnetic forces were obtained using Gauss pseudospectral method. Three performance criteria were chosen as minimum time, minimum acceleration of the separation distance and minimum control acceleration. Finally, three release examples including expansion along separation distance, rotation in orbital plane and stable formation reconfiguration were given to demonstrate the feasibility of this method. Results indicated that the release trajectories can converge to optimal solutions effectively and the concept of release companion satellites using electromagnetic forces is practicable.

  20. 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

  1. Release and control of hydrogen sulfide during sludge thermal drying

    Energy Technology Data Exchange (ETDEWEB)

    Weng, Huanxin; Dai, Zhixin; Ji, Zhongqiang; Gao, Caixia; Liu, Chongxuan

    2015-04-15

    The release of hydrogen sulfide (H2S) during sludge drying is a major environmental problem because of its toxicity to human health. A series of experiments were performed to investigate the mechanisms and factors controlling the H2S release. Results of this study show that: 1) the biomass and activity of sulfate-reducing bacteria (SRB) in sludge were the major factors controlling the amount of H2S release, 2) the sludge drying temperature had an important effect on both the extent and the timing of H2S release from the sludge, and 3) decreasing sludge pH increased the H2S release. Based on the findings from this study, a new system that integrates sludge drying and H2S gas treatment was developed to reduce the amount of H2S released from sludge treatments.

  2. Modifying sorbents in controlled release formulations to prevent herbicides pollution

    Energy Technology Data Exchange (ETDEWEB)

    Cespedes, F.F.; Sanchez, M.V.; Garcia, S.P.; Perez, M.F. [University of Almeria, Almeria (Spain). Dept. of Inorganic Chemistry

    2007-10-15

    The herbicides chloridazon and metribuzin, identified as groundwater pollutants, were incorporated in alginate-based granules to obtain controlled release properties. In this research the effect of incorporation of sorbents such as bentonite, anthracite and activated carbon in alginate basic formulation were not only studied on encapsulation efficiency but also on the release rate of herbicides which was studied using water release kinetic tests. In addition, sorption studies of herbicides with bentonite, anthracite and activated carbon were made. The kinetic experiments of chloridazon and metribuzin release in water have shown that the release rate is higher in metribuzin systems than in those prepared with chloridazon, which has lower water solubility. Besides, it can be deduced that the use of sorbents reduces the release rate of the chloridazon and metribuzin in comparison to the technical product and to the alginate formulation without sorbents. The highest decrease in release rate corresponds to the formulations prepared with activated carbon as a sorbent. The water uptake, permeability, and time taken for 50% of the active ingredient to be released into water, were calculated to compare the formulations. On the basis of a parameter of an empirical equation used to fit the herbicide release data, the release of chloridazon and metribuzin from the various formulations into water is controlled by a diffusion mechanism.

  3. Protein microspheres as suitable devices for piroxicam release.

    Science.gov (United States)

    Silva, Raquel; Ferreira, Helena; Carvalho, Ana C; Gomes, Andreia C; Cavaco-Paulo, Artur

    2012-04-01

    Bovine serum albumin-piroxicam (BSA-piroxicam) and human serum albumin-piroxicam (HSA-piroxicam) microspheres were sonochemically prepared and characterized. The use of polyvinyl alcohol (PVA) lead to an improvement of formulation characteristics, including smaller size, lower polydispersity index (PDl), higher entrapment efficiency and higher stability. The release kinetics of these proteinaceous microspheres was determined in presence of protease, indicating an anomalous drug transport mechanism (diffusion and polymer degradation). In presence of higher protease concentration, BSA microspheres exhibit Case II transport, leading to zero order release (protein degradation). These proteinaceous devices did not show cytotoxicity against human skin fibroblasts in vitro, for range concentrations below to 300 mg L(-1), greatly supporting their potential application in the treatment of inflammatory diseases.

  4. Design of whey protein nanostructures for incorporation and release of nutraceutical compounds in food.

    Science.gov (United States)

    Ramos, Oscar L; Pereira, Ricardo N; Martins, Artur; Rodrigues, Rui; Fuciños, Clara; Teixeira, José A; Pastrana, Lorenzo; Malcata, F Xavier; Vicente, António A

    2017-05-03

    Whey proteins are widely used as nutritional and functional ingredients in formulated foods because they are relatively inexpensive, generally recognized as safe (GRAS) ingredient, and possess important biological, physical, and chemical functionalities. Denaturation and aggregation behavior of these proteins is of particular relevance toward manufacture of novel nanostructures with a number of potential uses. When these processes are properly engineered and controlled, whey proteins may be formed into nanohydrogels, nanofibrils, or nanotubes and be used as carrier of bioactive compounds. This review intends to discuss the latest understandings of nanoscale phenomena of whey protein denaturation and aggregation that may contribute for the design of protein nanostructures. Whey protein aggregation and gelation pathways under different processing and environmental conditions such as microwave heating, high voltage, and moderate electrical fields, high pressure, temperature, pH, and ionic strength were critically assessed. Moreover, several potential applications of nanohydrogels, nanofibrils, and nanotubes for controlled release of nutraceutical compounds (e.g. probiotics, vitamins, antioxidants, and peptides) were also included. Controlling the size of protein networks at nanoscale through application of different processing and environmental conditions can open perspectives for development of nanostructures with new or improved functionalities for incorporation and release of nutraceuticals in food matrices.

  5. Best Practices for Controlling Lead and Copper Release

    Science.gov (United States)

    Presentation draft, covering summary of current state-of-the-art knowledge for the best treatment strategies for minimizing lead release and controlling copper release. The presentation is intended to aid with compliance with the Lead and Copper Rule, but also provide a guide to...

  6. Preparation and evaluation of controlled release tablets of carvedilol

    Directory of Open Access Journals (Sweden)

    Varahala Setti M

    2009-01-01

    Full Text Available The objective of the present investigation is to design and evaluate controlled release tablets of carvedilol, employing synthetic polymers like polyethylene oxides, of different molecular weights as release retarding materials and to select the optimized formulation based on the pharmacokinetics of carvedilol. Matrix tablets each containing 80 mg of carvedilol were formulated employing PEO N60 K, PEO 301, and PEO 303 as release-retarding polymers and β Cyclodextrin and HP β cyclodextrin as release modulators from the matrix. Carvedilol release from the formulated tablets was very slow. Hence the release was modulated with the use of cyclodextrins. The dissolution from the matrix tablets was spread over more than 24 hours and depended on the type of polymer, its concentration and the type of cyclodextrin used. All the matrix tablets prepared using polyethylene oxides showed very good controlled release over more than 24 hours. The matrix tablets prepared using HP β cyclodextrin showed a higher dissolution rate and gave a dissolution profile that was comparable to the theoretical sustained release needed for once-a-day administration of carvedilol. The drug release mechanism from the matrix tablets was found to be quasi Fickian mechanism.

  7. Mitofilin regulates cytochrome c release during apoptosis by controlling mitochondrial cristae remodeling

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui-feng; Zhao, Guo-wei; Liang, Shu-ting; Zhang, Yuan; Sun, Li-hong [National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), 5 Dong Dan San Tiao, Beijing 100005 (China); Chen, Hou-zao, E-mail: houzao@gmail.com [National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), 5 Dong Dan San Tiao, Beijing 100005 (China); Liu, De-pei, E-mail: liudp@pumc.edu.cn [National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), 5 Dong Dan San Tiao, Beijing 100005 (China)

    2012-11-09

    Highlights: Black-Right-Pointing-Pointer Mitofilin deficiency caused disruption of the cristae structures in HeLa cells. Black-Right-Pointing-Pointer Mitofilin deficiency reduced cell proliferation and increased cell sensitivity to apoptotic stimuli. Black-Right-Pointing-Pointer Mitofilin deficiency accelerated the release of cytochrome c from mitochondria. Black-Right-Pointing-Pointer Mitofilin deficiency accelerated STS-induced intrinsic apoptotic pathway without interfering with the activation of Bax. -- Abstract: Mitochondria amplify caspase-dependent apoptosis by releasing proapoptotic proteins, especially cytochrome c. This process is accompanied by mitochondrial cristae remodeling. Our studies demonstrated that mitofilin, a mitochondrial inner membrane protein, acted as a cristae controller to regulate cytochrome c release during apoptosis. Knockdown of mitofilin in HeLa cells with RNAi led to fragmentation of the mitochondrial network and disorganization of the cristae. Mitofilin-deficient cells showed cytochrome c redistribution between mitochondrial cristae and the intermembrane space (IMS) upon intrinsic apoptotic stimuli. In vitro cytochrome c release experiments further confirmed that, compared with the control group, tBid treatment led to an increase in cytochrome c release from mitofilin-deficient mitochondria. Furthermore, the cells with mitofilin knockdown were more prone to apoptosis by accelerating cytochrome c release upon the intrinsic apoptotic stimuli than controls. Moreover, mitofilin deficiency did not interfere with the activation of proapoptotic member Bax upon intrinsic apoptotic stimuli. Thus, mitofilin distinctly functions in cristae remodeling and controls cytochrome c release during apoptosis.

  8. 骨形态发生蛋白2缓释载体的研究进展%Research Progress of Bone Morphogenetic Protein-2 Controlled-release Carrier

    Institute of Scientific and Technical Information of China (English)

    张以财; 焦力刚

    2012-01-01

    自体骨移植一直是骨修复的"金标准",但仍存在一些问题.异体骨移植同样存在着骨愈合缓慢及排斥反应等问题.随着组织工程学的发展,应用骨组织工程方法来修复骨缺损成为研究热点.骨组织工程主要包括支架材料、种子细胞、生长因子三个方面.骨形态发生蛋白2是目前最强的促骨生长因子,其在体内半衰期很短,必须依靠缓释载体才能发挥其较长效的促骨生长作用.%Autogenous bone graft has long been the " golden standard" of bone repair, while there are some remaining problems. Allograft also have many problems, such as slow bone healing and rejection etc. . With the development of tissue engineering, lots of eyes focus on bone tissue engineering to repair bone defects. There are three key points in bone tissue engineering namely scaffolds, seed cells and growth factor. Bone morphogenetic protein-2 is the most efficient factor to promote bone growth so far,but it has a very short half-time in vivo, which must rely on control-released carrier to fulfill its long-term bone growth-promoting effect.

  9. 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.

  10. Controlled Release of Imidacloprid from Poly Styrene-Diacetone - Nanoformulation

    Science.gov (United States)

    Qian, Kun; Guo, Yanzhen; He, Lin

    2012-01-01

    Imidacloprid is a neonicotinoids insecticide, which is important for the cash crops such as tomato, rape and so on. The conventional formulation does not only increase the loss of pesticide but also leads to environmental pollution. Controlled-release formulations of pesticide are highly desirable not only for attaining the most effective utilization of the pesticide, but also for reducing environmental pollution. Pesticide imidacloprid was incorporated in poly (styrene-diacetone crylamide)-based formulation to obtain controlled release properties, and the imidacloprid nanocontrolled release formulation was characterized by infrared (IR) and field emission scanning electron microscope (FESEM). Factors related to loading efficiency, swelling and release behaviors of the formulation were investigated. It showed that the loading efficiency could reach about 40% (w/w). The values for the diffusion exponent "n" were in the range of 0.31-0.58, which indicated that the release of imidacloprid was diffusion-controlled. The time taken for 50% of the active ingredient to be released into water, T50, was also calculated for the comparison of formulations in different conditions. The results showed that the formulation with higher temperature and more diacetone crylamide had lower value of T50, which means a quicker release of the active ingredient. This study highlighted some pieces of evidence that improved pesticide incorporation and slower release were linked to potential interactions between the pesticide and the polymer.

  11. Encapsulated Urea-Kaolinite Nanocomposite for Controlled Release Fertilizer Formulations

    National Research Council Canada - National Science Library

    Sempeho, Siafu Ibahati; Kim, Hee Taik; Mubofu, Egid; Pogrebnoi, Alexander; Shao, Godlisten; Hilonga, Askwar

    2015-01-01

    Urea controlled release fertilizer (CRF) was prepared via kaolinite intercalation followed by gum arabic encapsulation in an attempt to reduce its severe losses associated with dissolution, hydrolysis, and diffusion...

  12. Trigger release liposome systems: local and remote controlled delivery?

    Science.gov (United States)

    Bibi, Sagida; Lattmann, E; Mohammed, Afzal R; Perrie, Yvonne

    2012-01-01

    Target-specific delivery has become an integral area of research in order to increase bioavailability and reduce the toxic effects of drugs. As a drug-delivery option, trigger-release liposomes offer sophisticated targeting and greater control-release capabilities. These are broadly divided into two categories; those that utilise the local environment of the target site where there may be an upregulation in certain enzymes or a change in pH and those liposomes that are triggered by an external physical stimulus such as heat, ultrasound or light. These release mechanisms offer a greater degree of control over when and where the drug is released; furthermore, targeting of diseased tissue is enhanced by incorporation of target-specific components such as antibodies. This review aims to show the development of such trigger release liposome systems and the current research in this field.

  13. Presynaptic Protein Synthesis Is Required for Long-Term Plasticity of GABA Release.

    Science.gov (United States)

    Younts, Thomas J; Monday, Hannah R; Dudok, Barna; Klein, Matthew E; Jordan, Bryen A; Katona, István; Castillo, Pablo E

    2016-10-19

    Long-term changes of neurotransmitter release are critical for proper brain function. However, the molecular mechanisms underlying these changes are poorly understood. While protein synthesis is crucial for the consolidation of postsynaptic plasticity, whether and how protein synthesis regulates presynaptic plasticity in the mature mammalian brain remain unclear. Here, using paired whole-cell recordings in rodent hippocampal slices, we report that presynaptic protein synthesis is required for long-term, but not short-term, plasticity of GABA release from type 1 cannabinoid receptor (CB1)-expressing axons. This long-term depression of inhibitory transmission (iLTD) involves cap-dependent protein synthesis in presynaptic interneuron axons, but not somata. Translation is required during the induction, but not maintenance, of iLTD. Mechanistically, CB1 activation enhances protein synthesis via the mTOR pathway. Furthermore, using super-resolution STORM microscopy, we revealed eukaryotic ribosomes in CB1-expressing axon terminals. These findings suggest that presynaptic local protein synthesis controls neurotransmitter release during long-term plasticity in the mature mammalian brain. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Controlling proteins through molecular springs.

    Science.gov (United States)

    Zocchi, Giovanni

    2009-01-01

    We argue that the mechanical control of proteins-the notion of controlling chemical reactions and processes by mechanics-is conceptually interesting. We give a brief review of the main accomplishments so far, leading to our present approach of using DNA molecular springs to exert controlled stresses on proteins. Our focus is on the physical principles that underlie both artificial mechanochemical devices and natural mechanisms of allostery.

  15. Nutrients Release from a Novel Gel-Based Slow/Controlled Release Fertilizer

    OpenAIRE

    Ding, H.; Y. S. Zhang; Li, W. H.; Zheng, X. Z.; Wang, M. K.; Tang, L. N.; Chen, D. L.

    2016-01-01

    A novel gel-based slow/controlled release fertilizer (G-CRF) was developed, which was produced by combining various natural, seminatural, and/or synthetic organic macromolecule materials and natural inorganic mineral with conventional NPK fertilizers. Its nutrient release characteristics were studied to compare with conventional fertilizers through the soil column leaching method. The influences of soil factors, including temperature, pH, water, and nutrient contents in the G-CRF on nutrient ...

  16. POE-PEG-POE triblock copolymeric microspheres containing protein. II. Polymer erosion and protein release mechanism.

    Science.gov (United States)

    Wan, J P; Yang, Y Y; Chung, T S; Tan, D; Ng, S; Heller, J

    2001-07-10

    The first paper of this series presented the fabrication and characterization of POE-PEG-POE triblock copolymeric microspheres containing protein. In this paper, we focus on the polymer erosion and the mechanism of protein release. Fourteen-week in vitro behaviors of POE-PEG-POE microspheres loaded with bovine serum albumin (BSA) have been monitored. SEM micrographs reveal that after 14-week incubation in PBS buffer, pH 7.4, 37 degrees C, the polymeric particles remain spherical despite mass loss of almost 90%. On the other hand, molecular weight undergoes a high initial loss of 38% and 44% during the first 2-week incubation for POE-PEG(5%)-POE and POE-PEG(10%)-POE, respectively. Then, it keeps relatively unchanged over 12 weeks. However, POE-PEG(20%)-POE copolymer provides a better compatibility between the POE and PEG blocks. Hydrolysis is homogeneous through the polymer backbone. Thus, its molecular weight remains relatively constant and mass loss shows quite sustained over the 14-week in vitro release. The similar phenomena are observed in the polydispersity index of the degrading copolymers. SDS-PAGE of the encapsulated BSA within the POE-PEG(5%)-POE microspheres displays that the structural integrity of BSA is intact for at least 8 weeks due to a mild environment provided by the copolymer. In addition, XPS and FTIR are utilized to investigate protein behaviors in the degrading microspheres. Protein release from the POE-PEG-POE microspheres shows a biphasic pattern, characterized by an initial stage followed by a non-detectable release. The non-release phase is dominated by either slow polymer degradation or dense microsphere matrix structures. The microsphere formulation is optimized and a sustained protein release over 2 weeks is achieved by using POE-PEG(20%)-POE at a high protein loading.

  17. Controlling Liquid Release by Compressing Electrospun Nanowebs

    Directory of Open Access Journals (Sweden)

    K.G. Kornev

    2009-09-01

    Full Text Available Electrospun nanowebs with pores ranging from nanometers to micrometers, constitute new materials with enhanced absorbency and ability to retain liquids in pores for a long period of time. These materials can be used as nanofluidic probes collecting minute amount of liquids. However, extraction of liquids from nanofibrous materials presents a problem: menisci in the interfiber pores create very high suction pressure which holds the liquid inside the material. This problem can be resolved if the probe is completely filled with the liquid: menisci at the probe edges become flat to establish a pressure equilibrium with the atmosphere. Therefore, one can take advantage of the nanoweb softness and extract liquid by mechanically deforming the nanowebs. We show that the liquid-saturated nanowebs follow the Voigt-type rheology upon loading. We theoretically explain this behavior and derive the relations between the Voigt phenomenological parameters, nanoweb permeability and compression modulus. We show that the limiting deformations follow the Hooke’s law which assumes linear relation between the extracted volume of liquid and the applied load. Because of this predictable behavior, the nanoweb probes can be engineered to release minute liquid doses upon compression. The developed experimental methodology can be used for characterization of nanostructured materials which otherwise impossible to analyze by using the existing instruments.

  18. Nanoporous Silicified Phospholipids and Application to Controlled Glycolic Acid Release

    Directory of Open Access Journals (Sweden)

    Kang SangHwa

    2008-01-01

    Full Text Available Abstract This work demonstrates the synthesis and characterization of novel nanoporous silicified phospholipid bilayers assembled inorganic powders. The materials are obtained by silicification process with silica precursor at the hydrophilic region of phospholipid bilayers. This process involves the co-assembly of a chemically active phospholipids bilayer within the ordered porosity of a silica matrix and holds promise as a novel application for controlled drug release or drug containers with a high level of specificity and throughput. The controlled release application of the synthesized materials was achieved to glycolic acid, and obtained a zero-order release pattern due to the nanoporosity.

  19. [Drug release system controlled by near infrared light].

    Science.gov (United States)

    Niidome, Takuro

    2013-01-01

    Gold nanorods have absorption bands in the near-infrared region; in this spectral range, light penetrates deeply into tissues. The absorbed light energy is converted into heat by gold nanorods. This is the so-called photothermal effect. Gold nanorods are therefore expected to act not only as thermal converters for photothermal therapy, but also as controllers for drug-release systems responding to irradiation with near-infrared light. To achieve a controlled-release system that could be triggered by light irradiation, the gold nanorods were modified with double-stranded DNA (dsDNA). When the dsDNA-modified gold nanorods were irradiated with near-infrared light, single-stranded DNA (ssDNA) was released from the gold nanorods because of the photothermal effect. The release of ssDNA was also observed in tumors grown on mice after near-infrared light irradiation. We also proposed a different controlled-release system responding to near-infrared light. Gold nanorods were modified with polyethylene glycol (PEG) through Diels-Alder cycloadducts. When the gold nanorods were irradiated with near-infrared light, the PEG chains were released from the gold nanorods because of the retro Diels-Alder reaction induced by the photothermal effect. Such controlled-release systems triggered by near-infrared light irradiation will be expanded for gold nanorod drug delivery system applications.

  20. Controlling allosteric networks in proteins

    Science.gov (United States)

    Dokholyan, Nikolay

    2013-03-01

    We present a novel methodology based on graph theory and discrete molecular dynamics simulations for delineating allosteric pathways in proteins. We use this methodology to uncover the structural mechanisms responsible for coupling of distal sites on proteins and utilize it for allosteric modulation of proteins. We will present examples where inference of allosteric networks and its rewiring allows us to ``rescue'' cystic fibrosis transmembrane conductance regulator (CFTR), a protein associated with fatal genetic disease cystic fibrosis. We also use our methodology to control protein function allosterically. We design a novel protein domain that can be inserted into identified allosteric site of target protein. Using a drug that binds to our domain, we alter the function of the target protein. We successfully tested this methodology in vitro, in living cells and in zebrafish. We further demonstrate transferability of our allosteric modulation methodology to other systems and extend it to become ligh-activatable.

  1. 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.

  2. Modifying sorbents in controlled release formulations to prevent herbicides pollution.

    Science.gov (United States)

    Flores Céspedes, F; Villafranca Sánchez, M; Pérez García, S; Fernández Pérez, M

    2007-10-01

    The herbicides chloridazon and metribuzin, identified as groundwater pollutants, were incorporated in alginate-based granules to obtain controlled release properties. In this research the effect of incorporation of sorbents such as bentonite, anthracite and activated carbon in alginate basic formulation were not only studied on encapsulation efficiency but also on the release rate of herbicides which was studied using water release kinetic tests. In addition, sorption studies of herbicides with bentonite, anthracite and activated carbon were made. The kinetic experiments of chloridazon and metribuzin release in water have shown that the release rate is higher in metribuzin systems than in those prepared with chloridazon, which has lower water solubility. Besides, it can be deduced that the use of sorbents reduces the release rate of the chloridazon and metribuzin in comparison to the technical product and to the alginate formulation without sorbents. The highest decrease in release rate corresponds to the formulations prepared with activated carbon as a sorbent. The water uptake, permeability, and time taken for 50% of the active ingredient to be released into water, T(50), were calculated to compare the formulations. On the basis of a parameter of an empirical equation used to fit the herbicide release data, the release of chloridazon and metribuzin from the various formulations into water is controlled by a diffusion mechanism. Sorption capacity of the sorbents for chloridazon and metribuzin, ranging from 0.53mgkg(-1) for the metribuzin sorption on bentonite to 2.03x10(5)mgkg(-1) for the sorption of chloridazon on the activated carbon, was the most important factor modulating the herbicide release.

  3. Assembly of bio-nanoparticles for double controlled drug release.

    Directory of Open Access Journals (Sweden)

    Wei Huang

    Full Text Available A critical limiting factor of chemotherapy is the unacceptably high toxicity. The use of nanoparticle based drug carriers has significantly reduced the side effects and facilitated the delivery of drugs. Source of the remaining side effect includes (1 the broad final in vivo distribution of the administrated nanoparticles, and (2 strong basal drug release from nanoparticles before they could reach the tumor. Despite the advances in pH-triggered release, undesirable basal drug release has been a constant challenge under in vivo conditions. In this study, functionalized single walled carbon nanohorn supported immunoliposomes were assembled for paclitaxel delivery. The immunoliposomes were formulated with polyethylene glycol, thermal stable and pH sensitive phospholipids. Each nanohorn was found to be encapsulated within one immunoliposome. Results showed a highly pH dependent release of paclitaxel in the presence of serum at body temperature with minimal basal release under physiological conditions. Upon acidification, paclitaxel was released at a steady rate over 30 days with a cumulative release of 90% of the loaded drug. The drug release results proved our hypothesized double controlled release mechanism from the nanoparticles. Other results showed the nanoparticles have doubled loading capacity compared to that of traditional liposomes and higher affinity to breast cancer cells overexpressing Her2 receptors. Internalized nanoparticles were found in lysosomes.

  4. Fabrication of ultrathin polyelectrolyte fibers and their controlled release properties.

    Science.gov (United States)

    Chunder, Anindarupa; Sarkar, Sourangsu; Yu, Yingbo; Zhai, Lei

    2007-08-01

    Ultrathin fibers comprising 2-weak polyelectrolytes, poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH) were fabricated using the electrospinning technique. Methylene blue (MB) was used as a model drug to evaluate the potential application of the fibers for drug delivery. The release of MB was controlled in a nonbuffered medium by changing the pH of the solution. The sustained release of MB in a phosphate buffered saline (PBS) solution was achieved by constructing perfluorosilane networks on the fiber surfaces as capping layers. Temperature controlled release of MB was obtained by depositing temperature sensitive PAA/poly(N-isopropylacrylamide) (PNIPAAM) multilayers onto the fiber surfaces. The controlled release of drugs from electrospun fibers have potential applications as drug carriers in biomedical science.

  5. Controlled release implants based on cast lipid blends.

    Science.gov (United States)

    Kreye, F; Siepmann, F; Zimmer, A; Willart, J F; Descamps, M; Siepmann, J

    2011-05-18

    The aim of this study was to use lipid:lipid blends as matrix formers in controlled release implants. The systems were prepared by melting and casting and thoroughly characterized before and after exposure to the release medium. Based on the experimental results, a mechanistic realistic mathematical model was used to get further insight into the underlying drug release mechanisms. Importantly, broad spectra of drug release patterns could be obtained by simply varying the lipid:lipid blend ratio in implants based on Precirol ATO 5 (glyceryl palmitostearate):Dynasan 120 (hardened soybean oil) mixtures loaded with propranolol hydrochloride. Release periods ranging from a few days up to several months could be provided. Interestingly, the drug release rate monotonically decreased with increasing Dynasan 120 content, except for implants containing about 20-25% Precirol, which exhibited surprisingly high release rates. This could be attributed to the incomplete miscibility of the two lipids at these blend ratios: DSC thermograms showed phase separation in these systems. This is likely to cause differences in the implants' microstructure, which determines the mobility of water and dissolved drug as well as the mechanical stability of the systems. Purely diffusion controlled drug release was only observed at Precirol ATO 5 contents around 5-10%. In all other cases, limited drug solubility effects or matrix former erosion are also expected to play a major role. Thus, lipid:lipid blends are very interesting matrix formers in controlled release implants. However, care must be taken with respect to the mutual miscibility of the compounds: in case of phase separation, surprisingly high drug release rates might be observed.

  6. Effects of Controlled Release Fertilizer on the Flag Leaves Senescence in Dry-land Wheat

    Directory of Open Access Journals (Sweden)

    Dandan Liu

    2013-05-01

    Full Text Available In order to select a reasonable controlled release fertilizer application method to slow down the senescence of flag leaf in dry-land wheat. The effects of controlled release fertilizer on soluble protein content, MDA content, the Catalase (CAT activity, the Superoxide Dismutase (SOD activity on the flag leaves senescence in dry-land wheat had been studied in the open field with the variety wheat Jimai22. The results indicated that, the combination application of controlled release fertilizer with conventional complex fertilizer on wheat was more conducive to the promotion of the soluble protein synthesis and it controlled the increasing of MDA content in flag leaf more effectively than the application of conventional complex fertilizer or controlled-release fertilizer alone on wheat. And it was more conductive to control or delay the process of flag leaf senescence with better maintenance of the SOD activity. The treatments in application of controlled release fertilization alone were conducive to these treatments with conventional complex fertilizer alone. Among these treatments, T6 was the best fertilization method with the lowest flag leaf senescence speed.

  7. Modeling controlled nutrient release from polymer coated fertilizers: diffusion release from single granules.

    Science.gov (United States)

    Shaviv, Avi; Raban, Smadar; Zaidel, Elina

    2003-05-15

    A comprehensive model describing the complex and "non-Fickian" (mathematically nonlinear) nature of the release from single granules of membrane coated, controlled release fertilizers (CRFs) is proposed consisting of three stages: i. a lag period during which water penetrates the coating of the granule dissolving part of the solid fertilizer in it ii. a period of linear release during which water penetration into and release out occur concomitantly while the total volume of the granules remains practically constant; and iii. a period of "decaying release", starting as the concentration inside the granule starts to decrease. A mathematical model was developed based on vapor and nutrient diffusion equations. The model predicts the release stages in terms of measurable geometrical and chemophysical parameters such as the following: the product of granule radius and coating thickness, water and solute permeability, saturation concentration of the fertilizer, and its density. The model successfully predicts the complex and "sigmoidal" pattern of release that is essential for matching plant temporal demand to ensure high agronomic and environmental effectiveness. It also lends itself to more complex statistical formulations which account for the large variability within large populations of coated CRFs and can serve for further improving CRF production and performance.

  8. 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.

  9. Development of controlled release tablet by optimizing HPMC: consideration of theoretical release and RSM.

    Science.gov (United States)

    Pani, Nihar R; Nath, Lila K

    2014-04-15

    The objective of the study was to develop controlled release tablets of nateglinide, a meglitinide derivative anti-diabetic drug, considering theoretical release profile and response surface methodology (RSM). 3(2) factorial design was utilized to optimize concentration of hydroxylpropylmethylcellulose (HPMC) K15M and K100M to obtain the desired responses (drug release at one and six hours). Theoretical release profile of drug for controlled release formulation was calculated and considered as reference for the determination of similarity factor (f2) and desimilarity factor (f1). RSM, f2 and f1 were used to select the optimum formulation. Formulation containing HPMC K15M (5%) and HPMC K100M (15%) was found optimum with desired responses with f2=86.05 and drug release profile followed zero order kinetics. Excipients used were compatible with drug, confirmed initially through DSC and IST study. The optimization of experiments was validated and optimum formulation was passed the stability study. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. 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

  11. 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.

  12. Nutrients Release from a Novel Gel-Based Slow/Controlled Release Fertilizer

    Directory of Open Access Journals (Sweden)

    H. Ding

    2016-01-01

    Full Text Available A novel gel-based slow/controlled release fertilizer (G-CRF was developed, which was produced by combining various natural, seminatural, and/or synthetic organic macromolecule materials and natural inorganic mineral with conventional NPK fertilizers. Its nutrient release characteristics were studied to compare with conventional fertilizers through the soil column leaching method. The influences of soil factors, including temperature, pH, water, and nutrient contents in the G-CRF on nutrient release, were also investigated through soil-water incubation method. These results indicated that the G-CRF had better effect on controlling release of N, P, and K nutrients, and the effect was more efficient when soil-water content was lower than 45% (w/w, temperature was below 35°C, and soil pH was in the range from weak acid to neutral. In addition, considering the effect of controlling nutrient release and cost of the materials in the G-CRF, it is recommended that the most feasible NPK nutrient contents in the G-CRF ranged from 30 to 35%.

  13. A novel controlled-release system for antibacterial enzyme lysostaphin delivery using hydroxyapatite/chitosan composite bone cement

    National Research Council Canada - National Science Library

    Xue, Bai; Zhang, Cheng; Wang, Yihan; Wang, Jincheng; Zhang, Jien; Lu, Min; Li, Guodong; Cao, Zhizhong; Huang, Qingshan

    2014-01-01

    In this work, a lysostaphin-loaded, control-released, self-setting and injectable porous bone cement with efficient protein delivery was prepared by a novel setting method using hydroxyapatite/chitosan (HA/CS) composite scaffold...

  14. A Novel Controlled-Release System for Antibacterial Enzyme Lysostaphin Delivery Using Hydroxyapatite/Chitosan Composite Bone Cement: e113797

    National Research Council Canada - National Science Library

    Bai Xue; Cheng Zhang; Yihan Wang; Jincheng Wang; Jien Zhang; Min Lu; Guodong Li; Zhizhong Cao; Qingshan Huang

    2014-01-01

      In this work, a lysostaphin-loaded, control-released, self-setting and injectable porous bone cement with efficient protein delivery was prepared by a novel setting method using hydroxyapatite/chitosan (HA/CS) composite scaffold...

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

    Science.gov (United States)

    Kan, Xianwen; Geng, Zhirong; Zhao, Yao; Wang, Zhilin; Zhu, Jun-Jie

    2009-04-01

    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 Fe3O4 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.

  16. 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.

  17. 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.

  18. Suilysin stimulates the release of heparin binding protein from neutrophils and increases vascular permeability in mice

    Directory of Open Access Journals (Sweden)

    Shaolong Chen

    2016-08-01

    Full Text Available Most of the deaths that occurred during two large outbreaks of Streptococcus suis (S. suis infections in 1998 and 2005 in China were caused by streptococcal toxic shock syndrome (STSS, which is characterized by increased vascular permeability. Heparin binding protein (HBP is thought to mediate the vascular leakage. The purpose of this study was to investigate the detailed mechanism underlying the release of HBP and the vascular leakage induced by S. suis. Significantly higher serum levels of HBP were detected in Chinese patients with STSS than in patients with meningitis or healthy controls. Suilysin (SLY is an exotoxin secreted by the highly virulent strain 05ZYH33, and it stimulated the release of HBP from the polymorphonuclear neutrophils and mediated vascular leakage in mice. The release of HBP induced by SLY was caused by a calcium influx-dependent degranulation. Analyses using a pharmacological approach revealed that the release of HBP induced by SLY was related to Toll-like receptor 4, p38 mitogen-activated protein kinase, and the 1-phosphatidylinositol 3-kinase pathway. It was also dependent on a G protein-coupled seven-membrane spanning receptor. The results of this study provide new insights into the vascular leakage in STSS associated with non-Group A streptococci, which could lead to the discovery of potential therapeutic targets for STSS associated with S. suis.

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

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    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)

  20. Preparation and Characterization of Oxidized Starch Polymer Microgels for Encapsulation and Controlled Release of Functional Ingredients

    NARCIS (Netherlands)

    Li, Yuan; de Vries, Renko; Slaghek, Ted; Timmermans, Johan; Stuart, Martien A. Cohen; Norde, Willem

    A novel biocompatible and biodegradable microgel system has been developed for controlled uptake and release of especially proteins. It contains TEMPO-oxidized potato starch polymers, which are chemically cross-linked by sodium trimetaphosphate (STMP). Physical chemical properties have been

  1. Controlled release of an anti-cancer drug from DNA structured nano-films

    Science.gov (United States)

    Cho, Younghyun; Lee, Jong Bum; Hong, Jinkee

    2014-02-01

    We demonstrate the generation of systemically releasable anti-cancer drugs from multilayer nanofilms. Nanofilms designed to drug release profiles in programmable fashion are promising new and alternative way for drug delivery. For the nanofilm structure, we synthesized various unique 3-dimensional anti cancer drug incorporated DNA origami structures (hairpin, Y, and X shaped) and assembled with peptide via layer-by-layer (LbL) deposition method. The key to the successful application of these nanofilms requires a novel approach of the influence of DNA architecture for the drug release from functional nano-sized surface. Herein, we have taken first steps in building and controlling the drug incorporated DNA origami based multilayered nanostructure. Our finding highlights the novel and unique drug release character of LbL systems in serum condition taken full advantages of DNA origami structure. This multilayer thin film dramatically affects not only the release profiles but also the structure stability in protein rich serum condition.

  2. Chemical analysis of substrates with controlled release fertilizer

    NARCIS (Netherlands)

    Kreij, de C.

    2004-01-01

    Water-soluble fertilizer added to media containing controlled release fertilizer cannot be analysed with the 1:1.5 volume water extract, because the latter increases the element content in the extract. During storage and stirring or mixing the substrate with the extractant, part of the controlled re

  3. Controlled release fertilizer improves quality of container longleaf pine seedlings

    Science.gov (United States)

    R. Kasten Dumroese; Jeff Parkhurst; James P. Barnett

    2005-01-01

    In an operational trial, increasing the amount of nitrogen (N) applied to container longleaf pine seedlings by incorporating controlled release fertilizer (CRF) into the media improved seedling growth and quality. Compared with control seedlings that received 40 mg N, seedlings receiving 66 mg N through CRF supplemented with liquid fertilizer had needles that were 4 in...

  4. Chemical analysis of substrates with controlled release fertilizer

    NARCIS (Netherlands)

    Kreij, de C.

    2004-01-01

    Water-soluble fertilizer added to media containing controlled release fertilizer cannot be analysed with the 1:1.5 volume water extract, because the latter increases the element content in the extract. During storage and stirring or mixing the substrate with the extractant, part of the controlled re

  5. [Controlled release hydromorphone for visceral, somatic and neuropathic pain].

    Science.gov (United States)

    Alon, E; Cachin, C

    2010-03-03

    The aim of this multicentre, longitudinal investigation was to document the efficacy and tolerability profiles of controlled release hydromorphone in patients with heavy visceral, somatic or neuropathic pain under practical conditions. To this end, a prospective observational study was conducted in 57 centres in Switzerland, on a total of 196 patients. After an average of 43 days of treatment with controlled release hydromorphone, the intensity of momentary pain dropped by 46.5% and that of maximum pain dropped by 41.3%, with the efficacy of the treatment being most pronounced with visceral and somatic pain. At the same time, the prevalence of sleep disorders as a result of pain decreased from initially 86.7% to 21.0%. Controlled release hydromorphone was excellently tolerated in this group of elderly (average age 70.6 years), multimorbid pain patients receiving various medical treatments (average of 2.4 drugs in addition to pain medication), even in the voluntary long-term extension study of up to 96 days. No medical interactions were reported. Six and thirteen weeks after introducing the treatment, 89.8% and 85.2%, respectively, were still taking controlled release hydromorphone. Controlled release hydromorphone is a recommendable option for practical treatment of heavy and extremely heavy pain of various genesis.

  6. 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 (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 <6μg/L and 9-14μg/L for surface contact and in liquid media, respectively. Either by surface contact or by immersion in growth medium or vegetable soup, the coated 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.

  7. Mechanoresponsive materials for drug delivery: Harnessing forces for controlled release.

    Science.gov (United States)

    Wang, Julia; Kaplan, Jonah A; Colson, Yolonda L; Grinstaff, Mark W

    2017-01-01

    Mechanically-activated delivery systems harness existing physiological and/or externally-applied forces to provide spatiotemporal control over the release of active agents. Current strategies to deliver therapeutic proteins and drugs use three types of mechanical stimuli: compression, tension, and shear. Based on the intended application, each stimulus requires specific material selection, in terms of substrate composition and size (e.g., macrostructured materials and nanomaterials), for optimal in vitro and in vivo performance. For example, compressive systems typically utilize hydrogels or elastomeric substrates that respond to and withstand cyclic compressive loading, whereas, tension-responsive systems use composites to compartmentalize payloads. Finally, shear-activated systems are based on nanoassemblies or microaggregates that respond to physiological or externally-applied shear stresses. In order to provide a comprehensive assessment of current research on mechanoresponsive drug delivery, the mechanical stimuli intrinsically present in the human body are first discussed, along with the mechanical forces typically applied during medical device interventions, followed by in-depth descriptions of compression, tension, and shear-mediated drug delivery devices. We conclude by summarizing the progress of current research aimed at integrating mechanoresponsive elements within these devices, identifying additional clinical opportunities for mechanically-activated systems, and discussing future prospects.

  8. 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.

  9. Controlled release of chlorhexidine from UDMA-TEGDMA resin.

    Science.gov (United States)

    Anusavice, K J; Zhang, N-Z; Shen, C

    2006-10-01

    Chlorhexidine salts are available in various formulations for dental applications. This study tested the hypothesis that the release of chlorhexidine from a urethane dimethacrylate and triethylene glycol dimethacrylate resin system can be effectively controlled by the chlorhexidine diacetate content and pH. The filler concentrations were 9.1, 23.1, or 33.3 wt%, and the filled resins were exposed to pH 4 and pH 6 acetate buffers. The results showed that Fickian diffusion was the dominant release mechanism. The rates of release were significantly higher in pH 4 buffer, which was attributed to the increase of chlorhexidine diacetate solubility at lower pH. The higher level of filler loading reduced the degree of polymerization, leading to a greater loss of organic components and higher chlorhexidine release rates.

  10. Protein corona change the drug release profile of nanocarriers: the "overlooked" factor at the nanobio interface.

    Science.gov (United States)

    Behzadi, Shahed; Serpooshan, Vahid; Sakhtianchi, Ramin; Müller, Beate; Landfester, Katharina; Crespy, Daniel; Mahmoudi, Morteza

    2014-11-01

    The emergence of nanocarrier systems in drug delivery applications has ushered in rapid development of new classes of therapeutic agents which can provide an essential breakthrough in the fight against refractory diseases. However, successful clinical application of nano-drug delivery devices has been limited mainly due to the lack of control on sustained release of therapeutics from the carriers. A wide range of sophisticated approaches employs the formation of crosslinkable, non-crosslinkable, stimuli-responsive polymer nanocarriers in order to enhance their delivery efficiency. Despite the extensive research conducted on the development of various nanocarriers, the effect of the biological milieu on the drug release profile of these constructs is not yet fully investigated. In particular, the formation of a protein corona on the surface of nanocarriers, when they interact with living organisms in vivo is largely decisive for their biological function. Using a number of synthetized (i.e., superparamagnetic iron oxide nanoparticles and polymeric nanocapsules) and commercialized nanocarriers (i.e., Abraxane®, albumin-bound paclitaxel drug), this study demonstrates that the protein corona can shield the nanocarriers and, consequently, alters the release profile of the drugs from the nanocarriers. More specifically, the protein corona could significantly reduce the burst effect of either protein conjugated nanocarriers or carriers with surface loaded drug (i.e., SPIONs). However, the corona shell only slightly changed the release profile of polymeric nanocapsules. Therefore, the intermediary, buffer effect of the protein shells on the surface of nanoscale carriers plays a crucial role in their successful high-yield applications in vivo.

  11. Press-coating of immediate release powders onto coated controlled release tablets with adhesives.

    Science.gov (United States)

    Waterman, Kenneth C; Fergione, Michael B

    2003-05-20

    A novel adhesive coating was developed that allows even small quantities of immediate-release (IR) powders to be press-coated onto controlled-release (CR), coated dosage forms without damaging the CR coating. The process was exemplified using a pseudoephedrine osmotic tablet (asymmetric membrane technology, AMT) where a powder weighing less than 25% of the core was pressed onto the osmotic tablet providing a final combination tablet with low friability. The dosage form with the adhesive plus the press-coated powder showed comparable sustained drug release rates to the untreated dosage form after an initial 2-h lag. The adhesive layer consisted of an approximately 100- microm coating of Eudragit RL, polyethylene glycol (PEG) and triethyl citrate (TEC) at a ratio of 5:3:1.2. This coating provides a practical balance between handleability before press-coating and good adhesion.

  12. Kinetics of protein-protein complex coacervation and biphasic release of salbutamol sulfate from coacervate matrix.

    Science.gov (United States)

    Tiwari, Ananya; Bindal, Sonal; Bohidar, H B

    2009-01-12

    Turbidimetric titration was used to initiate associative intermolecular interactions between a pair of protein molecules, gelatin-A and gelatin-B, having complementary charges that led to pH-induced liquid-liquid phase separation and the formation of complex coacervate. The stoichiometric binding ratio was found to be [gelatin-A]/[gelatin-B]=3:2. The size of soluble intermolecular aggregates present in the supernatant exhibited interesting time-dependent coacervation because of residual electrostatic interactions. Dynamic light scattering and turbidity studies provided a systematic account of coacervation behavior. Rheology studies attributed the softening of the coacervate matrix to the presence of encapsulated salbutamol sulfate. The in vitro drug release kinetics was probed in simulated gastric fluid medium at physiological temperature (37 degrees C), which showed biphasic behavior. The initial release kinetics exhibited an exponential growth to saturation behavior, followed by a slower logarithmic release process.

  13. 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.

  14. Biopolymers in controlled release devices for agricultural applications.

    Science.gov (United States)

    The use of biopolymers such as starch for agricultural applications including controlled release devices is growing due the environmental benefits. Recently, concerns have grown about the worldwide spread of parasitic mites (Varroa destructor) that infect colonies of honey bees (Apis mellifera L.). ...

  15. Formulation and Pharmacokinetic Evaluation of Controlled-Release ...

    African Journals Online (AJOL)

    ISSN: 1596-5996 (print); 1596-9827 (electronic) ... Purpose: To develop and optimize controlled-release (CR) oxybutynin chloride matrix tablets. Methods: ... of the tablet was developed. ... India). Hydroxypropyl methylcellulose (HPMC) 4KM CR and ethyl cellulose (EC) were ..... Lyrinel OROS, and OXY/CR5C4 in SGF media.

  16. Using Randomized Controlled Trials to Evaluate Interventions for Releasing Prisoners

    Science.gov (United States)

    Pettus-Davis, Carrie; Howard, Matthew Owen; Dunnigan, Allison; Scheyett, Anna M.; Roberts-Lewis, Amelia

    2016-01-01

    Randomized controlled trials (RCTs) are rarely used to evaluate social and behavioral interventions designed for releasing prisoners. Objective: We use a pilot RCT of a social support intervention (Support Matters) as a case example to discuss obstacles and strategies for conducting RCT intervention evaluations that span prison and community…

  17. Composition for the controlled release of active compounds

    NARCIS (Netherlands)

    Hovens, I.A.P.; Jongboom, R.O.J.; Stuut, P.I.

    1999-01-01

    The invention provides a composition for the controlled release of one or more biologically active substances encapsulated in a degradable biopolymer matrix, consisting of a thermoplastic and/or partly crystalline inulin. A plasticiser such as glycerol, and an emulsifier may be present. The active s

  18. 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

  19. Evaluation of Sterculia foetida gum as controlled release excipient.

    Science.gov (United States)

    Chivate, Amit Ashok; Poddar, Sushilkumar Sharatchandra; Abdul, Shajahan; Savant, Gaurav

    2008-01-01

    The purpose of the research was to evaluate Sterculia foetida gum as a hydrophilic matrix polymer for controlled release preparation. For evaluation as a matrix polymer; characterization of Sterculia foetida gum was done. Viscosity, pH, scanning electronmicrographs were determined. Different formulation aspects considered were: gum concentration (10-40%), particle size (75-420 microm) and type of fillers and those for dissolution studies; pH, and stirring speed were considered. Tablets prepared with Sterculia foetida gum were compared with tablets prepared with Hydroxymethylcellulose K15M. The release rate profiles were evaluated through different kinetic equations: zero-order, first-order, Higuchi, Hixon-Crowell and Korsemeyer and Peppas models. The scanning electronmicrographs showed that the gum particles were somewhat triangular. The viscosity of 1% solution was found to be 950 centipoise and pH was in range of 4-5. Suitable matrix release profile could be obtained at 40% gum concentration. Higher sustained release profiles were obtained for Sterculia foetida gum particles in size range of 76-125 microm. Notable influences were obtained for type of fillers. Significant differences were also observed with rotational speed and dissolution media pH. The in vitro release profiles indicated that tablets prepared from Sterculia foetida gum had higher retarding capacity than tablets prepared with Hydroxymethylcellulose K15M prepared tablets. The differential scanning calorimetry results indicated that there are no interactions of Sterculia foetida gum with diltiazem hydrochloride. It was observed that release of the drug followed through surface erosion and anomalous diffusion. Thus, it could be concluded that Sterculia foetida gum could be used a controlled release matrix polymer.

  20. 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)

  1. Multifunctional conducting fibres with electrically controlled release of ciprofloxacin.

    Science.gov (United States)

    Esrafilzadeh, Dorna; Razal, Joselito M; Moulton, Simon E; Stewart, Elise M; Wallace, Gordon G

    2013-08-10

    We hereby present a new method of producing coaxial conducting polymer fibres loaded with an antibiotic drug that can then be subsequently released (or sustained) in response to electrical stimulation. The method involves wet-spinning of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) fibre, which served as the inner core to the electropolymerised outer shell layer of polypyrrole (Ppy). Ciprofloxacin hydrochloride (Cipro) was selected as the model drug and as the dopant in the Ppy synthesis. The release of Cipro in phosphate buffered saline (PBS) from the fibres was controlled by switching the redox state of Ppy.Cipro layer. Released Cipro under passive and stimulated conditions were tested against Gram positive (Streptococcus pyogenes) and Gram negative (Escherichia coli) bacteria. Significant inhibition of bacterial growth was observed against both strains tested. These results confirm that Cipro retains antibacterial properties during fibre fabrication and electrochemically controlled release. In vitro cytotoxicity testing utilising the neural B35 cell line confirmed the cytocompatibility of the drug loaded conducting fibres. Electrical conductivity, cytocompatibility and tuning release profile from this flexible fibre can lead to promising bionic applications such as neuroprosthetics and localised drug delivery. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. 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.

  3. Controlling chitosan-based encapsulation for protein and vaccine delivery

    Science.gov (United States)

    Koppolu, Bhanu prasanth; Smith, Sean G.; Ravindranathan, Sruthi; Jayanthi, Srinivas; Kumar, Thallapuranam K.S.; Zaharoff, David A.

    2014-01-01

    Chitosan-based nano/microencapsulation is under increasing investigation for the delivery of drugs, biologics and vaccines. Despite widespread interest, the literature lacks a defined methodology to control chitosan particle size and drug/protein release kinetics. In this study, the effects of precipitation-coacervation formulation parameters on chitosan particle size, protein encapsulation efficiency and protein release were investigated. Chitosan particle sizes, which ranged from 300 nm to 3 μm, were influenced by chitosan concentration, chitosan molecular weight and addition rate of precipitant salt. The composition of precipitant salt played a significant role in particle formation with upper Hofmeister series salts containing strongly hydrated anions yielding particles with a low polydispersity index (PDI) while weaker anions resulted in aggregated particles with high PDIs. Sonication power had minimal effect on mean particle size, however, it significantly reduced polydispersity. Protein loading efficiencies in chitosan nano/microparticles, which ranged from 14.3% to 99.2%, was inversely related to the hydration strength of precipitant salts, protein molecular weight and directly related to the concentration and molecular weight of chitosan. Protein release rates increased with particle size and were generally inversely related to protein molecular weight. This study demonstrates that chitosan nano/microparticles with high protein loading efficiencies can be engineered with well-defined sizes and controllable release kinetics through manipulation of specific formulation parameters. PMID:24560459

  4. Tailoring liquid crystalline lipid nanomaterials for controlled release of macromolecules.

    Science.gov (United States)

    Bisset, Nicole B; Boyd, Ben J; Dong, Yao-Da

    2015-11-10

    Lipid-based liquid crystalline materials are being developed as drug delivery systems. However, the use of these materials for delivery of large macromolecules is currently hindered by the small size of the water channels in these structures limiting control over diffusion behaviour. The addition of the hydration-modulating agent, sucrose stearate, to phytantriol cubic phase under excess water conditions incrementally increased the size of these water channels. Inclusion of oleic acid enabled further control of swelling and de-swelling of the matrix via a pH triggerable system where at low pH the hexagonal phase is present and at higher pH the cubic phase is present. Fine control over the release of various sized model macromolecules is demonstrated, indicating future application to controlled loading and release of large macromolecules such as antibodies. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Direct effects of TNF-α on local fuel metabolism and cytokine levels in the placebo controlled bilaterally infused human leg; increased insulin sensitivity, increased net protein breakdown and increased IL-6 release

    DEFF Research Database (Denmark)

    Bach, Ermina; Nielsen, Bent Roni Ranghøj; Vendelbo, Mikkel H;

    2013-01-01

    Tumor necrosis factor-α (TNF-α) has widespread metabolic actions. Systemic TNF-α administration, however, generates a complex hormonal and metabolic response. Our study was designed to test whether regional, placebo-controlled TNF-α infusion directly affects insulin resistance and protein breakdo...... interest and may concurrently act to provide adequate tissue fuel supply and contribute to the occurrence of systemic hypoglycemia. This distinct metabolic feature places TNF-α among the rare insulin mimetics of human origin....

  6. Halloysite clay nanotubes for controlled release of protective agents.

    Science.gov (United States)

    Lvov, Yuri M; Shchukin, Dmitry G; Möhwald, Helmuth; Price, Ronald R

    2008-05-01

    Halloysite aluminosilicate nanotubes with a 15 nm lumen, 50 nm external diameter, and length of 800 +/- 300 nm have been developed as an entrapment system for loading, storage, and controlled release of anticorrosion agents and biocides. Fundamental research to enable the control of release rates from hours to months is being undertaken. By variation of internal fluidic properties, the formation of nanoshells over the nanotubes and by creation of smart caps at the tube ends it is possible to develop further means of controlling the rate of release. Anticorrosive halloysite coatings are in development and a self-healing approach has been developed for repair mechanisms through response activation to external impacts. In this Perspective, applications of halloysite as nanometer-scale containers are discussed, including the use of halloysite tubes as drug releasing agents, as biomimetic reaction vessels, and as additives in biocide and protective coatings. Halloysite nanotubes are available in thousands of tons, and remain sophisticated and novel natural nanomaterials which can be used for the loading of agents for metal and plastic anticorrosion and biocide protection.

  7. Control of contents and release kinetics in block copolymer vesicles

    Science.gov (United States)

    Eisenberg, Adi

    2005-03-01

    Block copolymer vesicles have received considerable attention recently because of a wide range of potential applications. In our group, the thermodynamic aspects of vesicle formation, including curvature stabilization, as well as active loading and release from vesicles have been the focus of recent research. The vesicles are prepared from an amphiphilic diblock copolymer such as polystyrene-block-poly(acrylic acid) at a low pH (2.5) by adding water to a solution in a common solvent; then the extenal pH is raised to 6.5, and the compound, such as doxorubicin or another amine, is added. Since the compund inside the vesicle becomes ionized at the low pH, it can only escape at a rate very much slower than that of the loading process. The permeability of the wall can be controlled by the presence of plasticizers for the polystyrene wall; the plasticizers partition between the wall and the external aqueous solution with a known partition coefficient, and can be removed from the wall by dialysis. Release is then studied under perfect sink conditions and is diffusional. It is noteworthy that the rates of both loading and release can be varied by more than two orders of magnitude by controlling the plasticizer content. Also, between the loading and release processes, the vesicle wall can be hardened by removal of the plasticizer by dialysis. This degree of control makes block copolymer vesicles a promising delivery vehicle for a range of materials, including drugs.

  8. CONTROLLED RELEASE FROM PDMAEMA GELS PREPARED BY GAMMA RADIATION

    Institute of Scientific and Technical Information of China (English)

    Ning Liu; Min Yi; Shuang-ji Chen; Hong-fei Ha

    2002-01-01

    Poly(N,N-dimethylaminoethyl methacrylate) (polyDMAEMA) hydrogels prepared by γ-irradiation showed obvious temperature-sensitivity in a temperature range of 38-40℃ and pH-sensitivity at pH = 2.5. They also showed electric response behavior although it was not typical. The hydrogels were used in controlled release at different pH, temperature, and electric voltage. The release rates of methylene blue (MB) from the gels at 52℃ and pH = 1.24 were faster than those at 20℃ and pH = 10.56, respectively. In addition, the release rate at a field voltage of 5.0 was also faster than that without electric field.

  9. Protein release from electrospun nonwovens: improving the release characteristics through rational combination of polyester blend matrices with polidocanol.

    Science.gov (United States)

    Puhl, Sebastian; Ilko, David; Li, Linhao; Holzgrabe, Ulrike; Meinel, Lorenz; Germershaus, Oliver

    2014-12-30

    Nonwoven scaffolds consisting of poly-ε-caprolactone (PCL), poly(lactic-co-glycolic acid) (PLGA) and polidocanol (PD), and loaded with lysozyme crystals were prepared by electrospinning. The composition of the matrix was varied and the effect of PD content in binary mixtures, and of PD and PLGA content in ternary mixtures regarding processability, fiber morphology, water sorption, swelling and drug release was investigated. Binary PCL/PD blend nonwovens showed a PD-dependent increase in swelling of up to 30% and of lysozyme burst release of up to 45% associated with changes of the fiber morphology. Furthermore, addition of free PD to the release medium resulted in a significant increase of lysozyme burst release from pure PCL nonwovens from approximately 2-35%. Using ternary PCL/PD/PLGA blends, matrix degradation could be significantly improved over PCL/PD blends, resulting in a biphasic release of lysozyme with constant release over 9 weeks, followed by constant release with a reduced rate over additional 4 weeks. Based on these results, protein release from PCL scaffolds is improved by blending with PD due to improved lysozyme desorption from the polymer surface and PD-dependent matrix swelling. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Optogenetic control of serotonin and dopamine release in Drosophila larvae.

    Science.gov (United States)

    Xiao, Ning; Privman, Eve; Venton, B Jill

    2014-08-20

    Optogenetic control of neurotransmitter release is an elegant method to investigate neurobiological mechanisms with millisecond precision and cell type-specific resolution. Channelrhodopsin-2 (ChR2) can be expressed in specific neurons, and blue light used to activate those neurons. Previously, in Drosophila, neurotransmitter release and uptake have been studied after continuous optical illumination. In this study, we investigated the effects of pulsed optical stimulation trains on serotonin or dopamine release in larval ventral nerve cords. In larvae with ChR2 expressed in serotonergic neurons, low-frequency stimulations produced a distinct, steady-state response while high-frequency patterns were peak shaped. Evoked serotonin release increased with increasing stimulation frequency and then plateaued. The steady-state response and the frequency dependence disappeared after administering the uptake inhibitor fluoxetine, indicating that uptake plays a significant role in regulating the extracellular serotonin concentration. Pulsed stimulations were also used to evoke dopamine release in flies expressing ChR2 in dopaminergic neurons and similar frequency dependence was observed. Release due to pulsed optical stimulations was modeled to determine the uptake kinetics. For serotonin, Vmax was 0.54 ± 0.07 μM/s and Km was 0.61 ± 0.04 μM; and for dopamine, Vmax was 0.12 ± 0.03 μM/s and Km was 0.45 ± 0.13 μM. The amount of serotonin released per stimulation pulse was 4.4 ± 1.0 nM, and the amount of dopamine was 1.6 ± 0.3 nM. Thus, pulsed optical stimulations can be used to mimic neuronal firing patterns and will allow Drosophila to be used as a model system for studying mechanisms underlying neurotransmission.

  11. Activation of protein kinase C inhibits synthesis and release of decidual prolactin

    Energy Technology Data Exchange (ETDEWEB)

    Harman, I.; Costello, A.; Ganong, B.; Bell, R.M.; Handwerger, S.

    1986-08-01

    Activation of calcium-activated, phospholipid-dependent protein kinase C by diacylglycerol and phorbol esters has been shown to mediate release of hormones in many systems. To determine whether protein kinase C activation is also involved in the regulation of prolactin release from human decidual, the authors have examined the effects of various acylglycerols and phorbol esters on the synthesis and release of prolactin from cultured human decidual cells. sn-1,2-Dioctanolyglycerol (diC8), which is known to stimulate protein kinase C in other systems, inhibited prolactin release in a dose-dependent manner with maximal inhibition of 53.1% at 100 M. Diolein (100 M), which also stimulates protein kinase C activity in some systems, inhibited prolactin release by 21.3%. Phorbol 12-myristate 13-acetate (PMA), phorbol 12,13-didecanoate, and 4US -phorbol 12,13-dibutyrate, which activate protein kinase C in other systems, also inhibited the release of prolactin, which the protein kinase C inactivate 4 -phorbol-12,13-didecanoate was without effect. The inhibition of prolactin release was secondary to a decrease in prolactin synthesis. Although diC8 and PMA inhibited the synthesis and release of prolactin, these agents had no effect on the synthesis or release of trichloroacetic acid-precipitable (TVS)methionine-labeled decidual proteins and did not cause the release of the cytosolic enzymes lactic dehydrogenase and alkaline phosphatase. DiC8 and PMA stimulates the specific activity of protein kinase C in decidual tissue by 14.6 and 14.0-fold, respectively. The inhibition of the synthesis and release of prolactin by diC8 and phorbol esters strongly implicates protein kinase C in the regulation of the production and release of prolactin from the decidua.

  12. Highly Efficient Thermoresponsive Nanocomposite for Controlled Release Applications

    Science.gov (United States)

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

    2016-06-01

    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.

  13. 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.

  14. Release Characteristics of Different N Forms in an Uncoated Slow/Controlled Release Compound Fertilizer

    Institute of Scientific and Technical Information of China (English)

    DONG Yan; WANG Zheng-yin

    2007-01-01

    This study examined the release characteristics of different N forms in an uncoated slow/controlled-release compound fertilizer (UCRF) and the N uptake and N-use efficiency by rice plants. Water dissolution, soil leaching, and pot experiments were employed. The dynamics of N release from the UCRF could be quantitatively described by three equations: the first-order kinetics equation [Nt = N0 (1-e-kt)], Elovich equation (Nt = a + blnt), and parabola equation (Nt = a + bt0.5), with the best fitting by the first-order kinetics equation for different N (r= 0.9569**-0.9999**). The release potentials (N0 values estimated by the first-order kinetics equation) of different N in the UCRF decreased in the order of total N > DON > urea-N > NH4+-N > NO3--N in water, and total N > NH4+-N > DON > urea-N > NO3--N in soil, respectively,being in accordance with cumulative amounts of N release. The constants of N release rate (k values and b values) for different N forms were in decreasing order of total N > DON > NH4+-N > NO3--N in water, whereas the k values were urea-N >DON > NH4+-N > total N > NO3--N, and the b values were total N > NH4+-N > DON > NO3--N > urea-N in soil. Compared with a common compound fertilizer, the N-use efficiency, N-agronomy efficiency, and N-physiological efficiency of the UCRF were increased by 11.4%, 8.32 kg kg-1, and 5.17 kg kg-1, respectively. The ratios of different N to total N in the UCRF showed significant correlation with N uptake by rice plants. The findings showed that the first-order kinetics equation [Nt=N0(1-e-kt)] could be used to describe the release characteristics of different N forms in the fertilizer. The UCRF containing different N forms was more effective in facilitating N uptake by rice compared with the common compound fertilizer containing single urea-N form.

  15. Controlled Release of Agrochemicals Intercalated into Montmorillonite Interlayer Space

    Directory of Open Access Journals (Sweden)

    Harrison Wanyika

    2014-01-01

    Full Text Available 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.

  16. Controlled Release of Agrochemicals Intercalated into Montmorillonite Interlayer Space

    Science.gov (United States)

    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. PMID:24696655

  17. Are fluoride releasing dental materials clinically effective on caries control?

    Science.gov (United States)

    Cury, Jaime Aparecido; de Oliveira, Branca Heloisa; dos Santos, Ana Paula Pires; Tenuta, Livia Maria Andaló

    2016-03-01

    (1) To describe caries lesions development and the role of fluoride in controlling disease progression; (2) to evaluate whether the use of fluoride-releasing pit and fissure sealants, bonding orthodontic agents and restorative materials, in comparison to a non-fluoride releasing material, reduces caries incidence in children or adults, and (3) to discuss how the anti-caries properties of these materials have been evaluated in vitro and in situ. The search was performed on the Cochrane Database of Systematic Reviews and on Medline via Pubmed. Caries is a biofilm-sugar dependent disease and as such it provokes progressive destruction of mineral structure of any dental surface - intact, sealed or restored - where biofilm remains accumulated and is regularly exposed to sugar. The mechanism of action of fluoride released from dental materials on caries is similar to that of fluoride found in dentifrices or other vehicles of fluoride delivery. Fluoride-releasing materials are unable to interfere with the formation of biofilm on dental surfaces adjacent to them or to inhibit acid production by dental biofilms. However, the fluoride released slows down the progression of caries lesions in tooth surfaces adjacent to dental materials. This effect has been clearly shown by in vitro and in situ studies but not in randomized clinical trials. The anti-caries effect of fluoride releasing materials is still not based on clinical evidence, and, in addition, it can be overwhelmed by fluoride delivered from dentifrices. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Controlled exosome release from the retinal pigment epithelium in situ.

    Science.gov (United States)

    Locke, Christina J; Congrove, Nicole R; Dismuke, W Michael; Bowen, Trent J; Stamer, W Daniel; McKay, Brian S

    2014-12-01

    Retinal Pigment Epithelial cells (RPE) express both GPR143 and myocilin, which interact in a signal transduction-dependent manner. In heterologous systems, activation of GPR143 with ligand causes transient recruitment of myocilin to internalized receptors, which appears to be the entry point of myocilin to the endocytic pathway. In some but not all cells, myocilin also traffics through the multivesicular body (MVB) and is released on the surface of exosomes in a signal transduction-dependent fashion. Little is known regarding the role of exosomes in RPE, but they likely serve as a mode of communication between the RPE and the outer retina. In this study, we used posterior poles with retina removed from fresh human donor eyes as a model to test the relationship between GPR143, myocilin, and exosomes in an endogenous system. We isolated exosomes released by RPE using differential centrifugation of media conditioned by the RPE for 25 min, and then characterized the exosomes using nanoparticle tracking to determine the number and size of the exosomes. Next, we tested whether ligand stimulation of GPR143 using l-DOPA altered RPE exosome release. Finally, we investigated whether myocilin was present on the exosomes released by RPE and whether l-DOPA stimulation of GPR143 caused recruitment of myocilin to the endocytic pathway, as we have previously observed using cultured cells. Activation of GPR143 halted RPE exosome release, while simultaneously recruiting myocilin to the endocytic compartment. Together, our results indicate that GPR143 and myocilin function in a signal transduction system that can control exosome release from RPE.

  19. Encapsulated Urea-Kaolinite Nanocomposite for Controlled Release Fertilizer Formulations

    OpenAIRE

    Siafu Ibahati Sempeho; Hee Taik Kim; Egid Mubofu; Alexander Pogrebnoi; Godlisten Shao; Askwar Hilonga

    2015-01-01

    Urea controlled release fertilizer (CRF) was prepared via kaolinite intercalation followed by gum arabic encapsulation in an attempt to reduce its severe losses associated with dissolution, hydrolysis, and diffusion. Following the beneficiation, the nonkaolinite fraction decreased from 39.58% to 0.36% whereas the kaolinite fraction increased from 60.42% to 99.64%. The X-ray diffractions showed that kaolinite was a major phase with FCC Bravais crystal lattice with particle sizes ranging betwee...

  20. Hybrid Porous Materials for Controlled Release and Catalysis

    OpenAIRE

    Liu, Rui

    2010-01-01

    First reported in 1992, ordered mesoporous materials exhibit unique features, such as regular pore geometry, high surface area, and large pore volume, and have shown great potential in various applications. This dissertation combines the knowledge from the field of ordered mesoporous materials and several other research areas to design advanced hybrid porous materials for controlled release and catalysis applications.The demand for better treatment of illness has led to ever-increasing effort...

  1. Smart nanofibers with a photoresponsive surface for controlled release.

    Science.gov (United States)

    Fu, Guo-Dong; Xu, Li-Qun; Yao, Fang; Li, Guo-Liang; Kang, En-Tang

    2009-11-01

    A novel photocontrolled "ON-OFF" release system for the alpha-cyclodextrin-5-fluorouracial (alpha-CD-5FU) prodrug, based on host-guest interaction on the photoresponsive and cross-linked nanofiber surface, was demonstrated. The nanofibers with a stimuli-responsive surface were electrospun from the block copolymer prepared via controlled radical polymerization, followed by surface modification via "Click Chemistry", and loading of the prodrug via host-guest interaction.

  2. Hybrid Porous Materials for Controlled Release and Catalysis

    OpenAIRE

    Liu, Rui

    2010-01-01

    First reported in 1992, ordered mesoporous materials exhibit unique features, such as regular pore geometry, high surface area, and large pore volume, and have shown great potential in various applications. This dissertation combines the knowledge from the field of ordered mesoporous materials and several other research areas to design advanced hybrid porous materials for controlled release and catalysis applications.The demand for better treatment of illness has led to ever-increasing effort...

  3. Encapsulated Urea-Kaolinite Nanocomposite for Controlled Release Fertilizer Formulations

    OpenAIRE

    Siafu Ibahati Sempeho; Hee Taik Kim; Egid Mubofu; Alexander Pogrebnoi; Godlisten Shao; Askwar Hilonga

    2015-01-01

    Urea controlled release fertilizer (CRF) was prepared via kaolinite intercalation followed by gum arabic encapsulation in an attempt to reduce its severe losses associated with dissolution, hydrolysis, and diffusion. Following the beneficiation, the nonkaolinite fraction decreased from 39.58% to 0.36% whereas the kaolinite fraction increased from 60.42% to 99.64%. The X-ray diffractions showed that kaolinite was a major phase with FCC Bravais crystal lattice with particle sizes ranging betwee...

  4. An oral controlled release matrix pellet formulation containing nanocrystalline ketoprofen.

    Science.gov (United States)

    Vergote, G J; Vervaet, C; Van Driessche, I; Hoste, S; De Smedt, S; Demeester, J; Jain, R A; Ruddy, S; Remon, J P

    2001-05-21

    A controlled release pellet formulation using a NanoCrystal colloidal dispersion of ketoprofen was developed. In order to be able to process the aqueous NanoCrystal colloidal dispersion into a hydrophobic solid dosage form a spray drying procedure was used. The in vitro dissolution profiles of wax based pellets loaded with nanocrystalline ketoprofen are compared with the profiles of wax based pellets loaded with microcrystalline ketoprofen and of a commercial sustained release ketoprofen formulation. Pellets were produced using a melt pelletisation technique. All pellet formulations were composed of a mixture of microcrystalline wax and starch derivatives. The starch derivatives used were waxy maltodextrin and drum dried corn starch. Varying the concentration of drum dried corn starch increased the release rate of ketoprofen but the ketoprofen recovery remained problematic. To increase the dissolution yield surfactants were utilised. The surfactants were either added during the production process of the NanoCrystal colloidal dispersion (sodium laurylsulphate) or during the pellet manufacturing process (Cremophor RH 40). Both methods resulted in a sustained but complete release of nanocrystalline ketoprofen from the matrix pellet formulations.

  5. Controlled release of 5-flurouracil from biomedical polyurethanes

    Indian Academy of Sciences (India)

    Reddy Seetharamareddy Harisha; Kallappa Mahadevappa Hosamani; Rangappa Sangappa Keri; Namdev Shelke; Vijay Kumar Wadi; Tejaraj M Aminabhavi

    2010-03-01

    Novel biodegradable aliphatic poly(ether-urethane)s (PEUs) based on pluronic F-68 (PLF68) and castor oil were synthesized by the solution polymerization technique. These polymers were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic spectroscopy (1HNMR) and gel permeation chromatography (GPC) to confirm the PEU formation and the molecular weight. Moderate molecular weight PEUs were obtained and converted into microspheres by solvent evaporation method to study the controlled release (CR) characteristics for 5-flurouracil (5-FU). PLF-68 acts as amphiphilic filler, which enhances the release of a hydrophobic drug such as 5-FU. Sizes of the microspheres as measured by laser light scattering technique ranged between 15 and 42 m. An increase in the size of particles was observed with increasing molar ratio of PLF-68 with respect to castor oil. The percentage encapsulation efficiency varied between 71 and 98. Surface morphology of the microspheres as studied by scanning electron microscopy (SEM) revealed the spherical nature of the particles with wrinkles on their surfaces. The release of 5-FU through the microspheres was investigated in pH 7.4-phosphate buffer. An increase in release rate was observed with increasing molar ratio of PLF68 with respect to castor oil.

  6. Encapsulation efficiency and controlled release characteristics of crosslinked polyacrylamide particles.

    Science.gov (United States)

    Sairam, Malladi; Babu, V Ramesh; Vijaya, Boya; Naidu, Kumar; Aminabhavi, Tejraj M

    2006-08-31

    Polyacrylamide (pAAm) particles crosslinked with N,N-methylenebis-acrylamide/ethylene glycol dimethacrylate (NNMBA/EGDMA) have been prepared in water-methanol medium by the dispersion polymerization using poly(vinyl pyrrolidone), PVP as a steric stabilizer. 5-fluorouracil an anticancer drug, has been loaded in situ into the crosslinked pAAm particles. Plain as well as drug loaded microparticles have been characterized by differential scanning calorimetry (DSC) and X-ray diffraction studies (XRD) and scanning electron microscopy (SEM). DSC and XRD studies have indicated a molecular level dispersion of the drug in pAAm particles during in situ loading and SEM pictures have shown the formation of spherical and oval-shaped particles. In vitro release of 5-fluorouracil from the crosslinked pAAm particles has been carried out in 7.4 pH buffer medium. Both encapsulation efficiency and release patterns are found to depend on the nature of the crosslinking agent, amount of crosslinking agent used and the amount of drug loaded. In vitro release studies indicated the controlled release of 5-fluorouracil up to 12 h.

  7. Encapsulated Urea-Kaolinite Nanocomposite for Controlled Release Fertilizer Formulations

    Directory of Open Access Journals (Sweden)

    Siafu Ibahati Sempeho

    2015-01-01

    Full Text Available Urea controlled release fertilizer (CRF was prepared via kaolinite intercalation followed by gum arabic encapsulation in an attempt to reduce its severe losses associated with dissolution, hydrolysis, and diffusion. Following the beneficiation, the nonkaolinite fraction decreased from 39.58% to 0.36% whereas the kaolinite fraction increased from 60.42% to 99.64%. The X-ray diffractions showed that kaolinite was a major phase with FCC Bravais crystal lattice with particle sizes ranging between 14.6 nm and 92.5 nm. The particle size varied with intercalation ratios with methanol intercalated kaolinite > DMSO-kaolinite > urea-kaolinite (KPDMU. Following intercalation, SEM analysis revealed a change of order from thick compact overlapping euhedral pseudohexagonal platelets to irregular booklets which later transformed to vermiform morphology and dispersed euhedral pseudohexagonal platelets. Besides, dispersed euhedral pseudohexagonal platelets were seen to coexist with blocky-vermicular booklets. In addition, a unique brain-form agglomeration which transformed into roundish particles mart was observed after encapsulation. The nanocomposites decomposed between 48 and 600°C. Release profiles showed that 100% of urea was released in 97 hours from KPDMU while 87% was released in 150 hours from the encapsulated nanocomposite. The findings established that it is possible to use Pugu kaolinite and gum arabic biopolymer to prepare urea CRF formulations.

  8. Surface-protein interactions on different stainless steel grades: effects of protein adsorption, surface changes and metal release.

    Science.gov (United States)

    Hedberg, Y; Wang, X; Hedberg, J; Lundin, M; Blomberg, E; Wallinder, I Odnevall

    2013-04-01

    Implantation using stainless steels (SS) is an example where an understanding of protein-induced metal release from SS is important when assessing potential toxicological risks. Here, the protein-induced metal release was investigated for austenitic (AISI 304, 310, and 316L), ferritic (AISI 430), and duplex (AISI 2205) grades in a phosphate buffered saline (PBS, pH 7.4) solution containing either bovine serum albumin (BSA) or lysozyme (LSZ). The results show that both BSA and LSZ induce a significant enrichment of chromium in the surface oxide of all stainless steel grades. Both proteins induced an enhanced extent of released iron, chromium, nickel and manganese, very significant in the case of BSA (up to 40-fold increase), whereas both proteins reduced the corrosion resistance of SS, with the reverse situation for iron metal (reduced corrosion rates and reduced metal release in the presence of proteins). A full monolayer coverage is necessary to induce the effects observed.

  9. 乳酸-羟基乙酸共聚物多肽蛋白类药物微球控释系统的突释与控制%Burst release and control of the delivery system of protein/peptide drug loaded poly(lactic-co-glycolic acid) microspheres

    Institute of Scientific and Technical Information of China (English)

    赵先英; 高继宁; 粟永萍; 刘毅敏; 肖湘

    2011-01-01

    BACKGROUND: Burst release is key technology that limits the wide application of protein/peptide microspheres. It should be a problem to be solved.OBJECTIVE: To make a detailed introduction about burst release reason, influence factors and reduction methods after analyzing recent progress of burst release and control of protein/peptide drug loaded poly(lactic-co-glycolic acid) (PLGA).METHODS: Relevant articles in PubMed and CNKI published 1999-01/2010-12 were searched by computer with the key words of “PLGA, peptide, protein, microspheres, burst release, control” in Chinese and English. Articles addressing originally identification, reliability, general analysis, and high correlation were included. Exclusive criteria: repetitive and obsolescent articles. A total of 24 articles were reserved for review.RESULTS AND CONCLUSION: We need to comprehend mechanism of burst release of protein/peptide microspheres to realize enlargement application. Burst release was influenced by multifactors, such as characters of PLGA, preparation methods and preparation parameters. Burst release could be reduced some degree by the control of the above mentioned. It is very important to research of new drugs.%背景:突释问题是限制多肽蛋白类微球广泛应用的一个关键技术问题,已经成为PLGA微球控释系统面临的一个亟待解决的问题.目的:分析近年来国内外对乳酸-羟基乙酸共聚物多肽蛋白类药物微球的突释与控制的研究,对突释的原因、影响突释的因素以及减少突释的方法与措施进行了详细的介绍.方法:应用计算机检索CNKI和PubMed数据库中1999-01/2010-12关于乳酸-羟基乙酸共聚物多肽蛋白类药物微球控释系统研究的文章,在标题和摘要中以"聚乳酸-羟基乙酸;多肽;蛋白;微球;突释;控制"或"PLGA; peptide; protein ; microspheres; burst release; control"为检索词进行检索.通过阅读标题和摘要进行初选,排出较陈旧和重复研究文献,

  10. Evaluation of the Components Released by Wine Yeast Strains on Protein Haze Formation in White Wine

    Directory of Open Access Journals (Sweden)

    Ellen Cristine Giese

    2016-12-01

    Full Text Available Cultures of 23 indigenous yeast strains (22 Saccharomyces cerevisiae and a non-Saccharomyces, Torulaspora delbrueckii, isolated from fermentation tanks at wineries in Castilla-La Mancha (Spain, and were performed under winemaking conditions using a synthetic must. Polysaccharide analysis and turbidity assays were conducted so as to observe the capacity of the released mannoproteins against protein haze formation in white wine, and 3 strains (2 Saccharomyces cerevisiae and T. delbrueckii were chosen for further experiments. The action of a commercial b-glucanolytic enzyme preparation (Lallzyme BETA®, and a β-(1→3-glucanase preparation from Trichoderma harzianum Rifai were evaluated to release polysaccharides from the different yeast strains’ cell walls. Protection against protein haze formation was strain dependent, and only two strains (Sc2 and Sc4 presented >50% stabilization in comparison to controls. Addition of β-glucanases did not increase the concentrations of polysaccharides in the fermentation musts; however, a significant increase of polymeric mannose (mannoproteins was detected using an enzymatic assay following total acid hydrolysis of the soluble polysaccharides. Enzymatic treatment presented positive effects and decreased protein haze formation in white wine. DOI http://dx.doi.org/10.17807/orbital.v8i6.869

  11. Kisspeptin regulates gonadotropin-releasing hormone secretion in gonadotropin-releasing hormone/enhanced green fluorescent protein transgenic rats

    Institute of Scientific and Technical Information of China (English)

    Haogang Xue; Chunying Yang; Xiaodong Ge; Weiqi Sun; Chun Li; Mingyu Qi

    2013-01-01

    Kisspeptin is essential for activation of the hypothalamo-pituitary-gonadal axis. In this study, we established gonadotropin-releasing hormone/enhanced green fluorescent protein transgenic rats. Rats were injected with 1, 10, or 100 pM kisspeptin-10, a peptide derived from full-length kisspeptin, into the arcuate nucleus and medial preoptic area, and with the kisspeptin antagonist peptide 234 into the lateral cerebral ventricle. The results of immunohistochemical staining revealed that pulsatile luteinizing hormone secretion was suppressed after injection of antagonist peptide 234 into the lateral cerebral ventricle, and a significant increase in luteinizing hormone level was observed after kisspeptin-10 injection into the arcuate nucleus and medial preoptic area. The results of an enzyme-linked immunosorbent assay showed that luteinizing hormone levels during the first hour of kisspeptin-10 infusion into the arcuate nucleus were significantly greater in the 100 pM kisspeptin-10 group than in the 10 pM kisspeptin-10 group. These findings indicate that kisspeptin directly promotes gonadotropin-releasing hormone secretion and luteinizing hormone release in gonadotropin-releasing hormone/enhanced green fluorescent protein transgenic rats. The arcuate nucleus is a key component of the kisspeptin-G protein-coupled receptor 54 signaling pathway underlying regulating luteinizing hormone pulse secretion.

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

    Energy Technology Data Exchange (ETDEWEB)

    Depan, D.; Misra, R.D.K., E-mail: dmisra@louisiana.edu

    2012-08-01

    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: Black-Right-Pointing-Pointer The novel synthesis of a hybrid nanostructured drug carrier is described. Black-Right-Pointing-Pointer The drug carrier exhibits high drug loading ability and is physically stable. Black-Right-Pointing-Pointer The high drug release is ascribed to a cavitation-type process.

  13. 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.

  14. 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.

  15. Dopamine control of LH release in the tench (Tinca tinca).

    Science.gov (United States)

    Podhorec, Peter; Socha, Magdalena; Sokolowska-Mikolajczyk, Miroslawa; Policar, Tomas; Svinger, Viktor W; Drozd, Borek; Kouril, Jan

    2012-01-01

    Tench (Tinca tinca) is apparently the only known member of the Cyprinidae in which ovulation is stimulated following administration of a low dose of GnRH analogue (GnRHa) without a dopamine inhibitor. This study evaluated LH release effectiveness of the most commonly used GnRHa and clarified whether LH secretion followed by ovulation is subject to inhibitory dopaminergic control in tench. Fish were intraperitoneally injected with three types of GnRHa, GnRHa with dopamine inhibitor metoclopramide (combined treatment), or the dopamine inhibitor metoclopramide alone. LH concentrations at five sampling times (0, 6, 12, 24, and 33 h) together with ovulation success and fecundity index were recorded. The combined treatment triggered an almost immediate LH release peak with a gradual decline, and resulted in a high ovulation rate. In contrast to the combined treatment, an application of GnRHa alone at 10 μg kg(-1) induced gradual increase of LH concentrations with peaks close to ovulation time, and with high ovulation success. Significant differences in LH concentrations at 6 and 12h and no differences in ovulation success were found between the combined and the GnRHa alone treatments. Metoclopramide alone induced a small increase in LH with no ovulation. The study presents clear evidence of dopaminergic control of LH release in tench, with a high ovulation rate obtained after application of GnRHa alone or in combination with dopamine inhibitor.

  16. A functional protein retention and release multilayer with high stability

    Science.gov (United States)

    Nie, Kun; An, Qi; Zhang, Yihe

    2016-04-01

    Effective and robust interfacial protein retention lies at the heart of the fabrication of protein-based functional interfaces, which is potentially applicable in catalysis, medical therapy, antifouling, and smart devices, but remains challenging due to the sensitive nature of proteins. This study reports a general protein retention strategy to spatial-temporally confine various types of proteins at interfacial regions. The proteins were preserved in mesoporous silica nanoparticles embedded in covalently woven multilayers. It is worth noting that the protein retention strategy effectively preserves the catalytic capabilities of the proteins, and the multilayer structure is robust enough to withstand the bubbling catalytic reactions and could be repeatedly used due to conservation of proteins. The spatiotemporal retention of proteins could be adjusted by varying the number of capping layers. Furthermore, we demonstrate that the protein-loaded interfacial layers could not only be used to construct catalytic-active interfaces, but also be integrated as the power-generating unit to propel a macroscopic floating device.Effective and robust interfacial protein retention lies at the heart of the fabrication of protein-based functional interfaces, which is potentially applicable in catalysis, medical therapy, antifouling, and smart devices, but remains challenging due to the sensitive nature of proteins. This study reports a general protein retention strategy to spatial-temporally confine various types of proteins at interfacial regions. The proteins were preserved in mesoporous silica nanoparticles embedded in covalently woven multilayers. It is worth noting that the protein retention strategy effectively preserves the catalytic capabilities of the proteins, and the multilayer structure is robust enough to withstand the bubbling catalytic reactions and could be repeatedly used due to conservation of proteins. The spatiotemporal retention of proteins could be adjusted by

  17. Optical control of insulin release using a photoswitchable sulfonylurea.

    Science.gov (United States)

    Broichhagen, Johannes; Schönberger, Matthias; Cork, Simon C; Frank, James A; Marchetti, Piero; Bugliani, Marco; Shapiro, A M James; Trapp, Stefan; Rutter, Guy A; Hodson, David J; Trauner, Dirk

    2014-10-14

    Sulfonylureas are widely prescribed for the treatment of type 2 diabetes mellitus (T2DM). Through their actions on ATP-sensitive potassium (KATP) channels, sulfonylureas boost insulin release from the pancreatic beta cell mass to restore glucose homeostasis. A limitation of these compounds is the elevated risk of developing hypoglycemia and cardiovascular disease, both potentially fatal complications. Here, we describe the design and development of a photoswitchable sulfonylurea, JB253, which reversibly and repeatedly blocks KATP channel activity following exposure to violet-blue light. Using in situ imaging and hormone assays, we further show that JB253 bestows light sensitivity upon rodent and human pancreatic beta cell function. Thus, JB253 enables the optical control of insulin release and may offer a valuable research tool for the interrogation of KATP channel function in health and T2DM.

  18. Controlled release of hydrophilic guest molecules from photoresponsive nucleolipid vesicles.

    Science.gov (United States)

    Sun, Yawei; Yan, Yongfeng; Wang, Mingqing; Chen, Cuixia; Xu, Hai; Lu, Jian R

    2013-07-10

    Amphiphilic hybrid nucleolipids bear the structural and functional hallmarks of both lipids and nucleic acids and hold great potential for biotechnological applications. However, further tailoring of their structures and properties for specific applications represents a major challenge. We here report a novel design and synthesis of a light-responsive nucleolipid by introducing an o-nitrobenzyl group that acts as a linker between a nucleotide and a lipid. The nucleolipid was applied readily to preparing smart vesicles and encapsulating hydrophilic guest molecules 5(6)-carboxyfluorescein (CF) in their inner aqueous phase. Upon light irradiation, their vesicular structure was disrupted as a result of the photolytic degradation of the nucleotide, resulting in CF release. Furthermore, temporally controlled CF release from these vesicles could be readily realized by turning on and off light. By demonstrating the molecular assembly and photodisassembly cycle, this report aims to stimulate further research exploring practical applications of nucleolipids.

  19. Chitosan Hydrogels for Chondroitin Sulphate Controlled Release: An Analytical Characterization

    Directory of Open Access Journals (Sweden)

    Annalisa Bianchera

    2014-01-01

    Full Text Available This paper provides an analytical characterization of chitosan scaffolds obtained by freeze-gelation toward the uptake and the controlled release of chondroitin sulphate (CS, as cartilage repair agent, under different pH conditions. Scanning electron microscopy (SEM, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR, and liquid chromatography-UV spectrophotometry (LC-UV techniques were exploited to obtain qualitative and quantitative descriptions of polymer and drug behaviour in the biomaterial. As for morphology, SEM analysis allowed the evaluation of scaffold porosity in terms of pore size and distribution both at the surface (Feret diameter 58±19 μm and on the cross section (Feret diameter 106±51 μm. LC and ATR-FTIR evidenced a pH-dependent CS loading and release behaviour, strongly highlighting the role of electrostatic forces on chitosan/chondroitin sulphate interactions.

  20. Thermal post-treatment alters nutrient release from a controlled-release fertilizer coated with a waterborne polymer

    Science.gov (United States)

    Zhou, Zijun; Du, Changwen; Li, Ting; Shen, Yazhen; Zhou, Jianmin

    2015-09-01

    Controlled-release fertilizers (CRF) use a controlled-release technology to enhance the nutrient use efficiency of crops. Many factors affect the release of nutrients from the waterborne polymer-coated CRF, but the effects of thermal post-treatments remain unclear. In this study, a waterborne polyacrylate-coated CRF was post-treated at different temperatures (30 °C, 60 °C, and 80 °C) and durations (2, 4, 8, 12, and 24 h) after being developed in the Wurster fluidized bed. To characterize the polyacrylate membrane, and hence to analyze the mechanism of nutrient release, Fourier transform mid-infrared spectroscopy, scanning electron microscopy, and atomic force microscopy were employed. The nutrient-release model of CRF post-treated at 30 °C was the inverse “L” curve, but an increased duration of the post-treatment had no effect. The nutrient-release model was “S” curve and nutrient-release period was enhanced at higher post-treatment temperatures, and increased post-treatment duration lengthened slowed nutrient release due to a more compact membrane and a smoother membrane surface as well as a promoted crosslinking action. CRF equipped with specified nutrient-release behaviors can be achieved by optimizing the thermal post-treatment parameters, which can contribute to the development and application of waterborne polymer-coated CRF and controlled-release technologies.

  1. Electrospinning of alginate/soy protein isolated nanofibers and their release characteristics for biomedical applications

    Directory of Open Access Journals (Sweden)

    Ratchada Wongkanya

    2017-09-01

    Full Text Available Natural polymer-based nanofibers with functions of loading and releasing bioactive cues or drugs have recently gained interest for biomedical applications. Nanotopography and large surface area to volume ratio of hydrophilic polymer fibers promote their use as carriers of hydrophilic drugs. Here, sodium alginate (SA and soy protein isolated (SPI blended fibers encapsulated with vancomycin were fabricated via electrospinning with the assistance of poly(ethylene oxide (PEO. Morphological results showed submicron-sized, smooth and uniform as-spun SA/PEO/SPI fibers with an average diameter of 200 nm. Beads on the fiber mats were formed with increasing SPI content in the blending system. The optimal polymer composition of the electrospinning solution was determined as 5.6/2.4/2 SA/PEO/SPI. Polymer blends were maintained after ionic “cross-linking”, as indicated by the FTIR result. Investigation of release characteristic of vancomycin-loaded SA/PEO/SPI electrospun fibers exhibited initial burst release followed by a controlled release after 2 days of immersion in a phosphate buffered saline. The release rate of SA/PEO/SPI fibers was significantly slower than that of SA/PEO fibers, and drug-loaded fibers inhibited bacterial growth against Staphylococcus aureus after 24 h of incubation. Non-toxicity and biocompatibility of the fibers were confirmed by an indirect cytotoxicity test using human dermal fibroblasts. These results suggest that the vancomycin-loaded SA/PEO/SPI blended fibers are a promising nanomaterial for use in biomedical fields such as scaffolds for tissue engineering and drug delivery systems.

  2. INVITED PAPER: Control of sudden releases in channel flow

    Science.gov (United States)

    Katopodes, Nikolaos D.

    2009-12-01

    We present a method for the detection and real-time control of chemical releases in channel flow. Sensor arrays capable of detecting a broad menu of chemical agents are required at strategic locations of the channel. The sensors detect the instantaneous, spatially distributed concentration of the chemical agent and transmit the associated information to a predictive control model. The model provides optimal operation scenarios for computer controlled bleed valves mounted on the channel walls and connected to a common manifold. Control and elimination of the chemical cloud are achieved by optimal blowing and suction of ambient fluid. Gradient information is obtained by use of adjoint equations, so optimization of the control actions is achieved with the highest possible efficiency. The control is optimized over a finite prediction horizon and instructions are sent to the valve manifold. Next, the sensor arrays detect all changes effected by the control and report them to the control model, which advances the process over the next control horizon. Non-reflective boundary conditions for the adjoint equations are derived by a characteristic analysis, which minimizes spurious information in the computation of sensitivities.

  3. Review on Medusa:a polymer-based sustained release technology for protein and peptide drugs.

    Science.gov (United States)

    Chan, Y-P; Meyrueix, R; Kravtzoff, R; Nicolas, F; Lundstrom, K

    2007-07-01

    The polymer-based Medusa system (Flamel Technologies) has been designed for slow release of therapeutic proteins and peptides. The Medusa II consists of a poly L-glutamate backbone grafted with hydrophobic alpha-tocopherol molecules, creating a colloidal suspension of nanoparticles (10 - 50 nm) in water. The sustained drug release is based on reversible drug interactions with hydrophobic nanodomains within the nanoparticles. In vivo, it is suggested that the therapeutic protein is displaced by endogenous proteins present in physiological fluids, leading to a slow drug release. The peak concentration is dramatically decreased and the protein release substantially extended. The Medusa technology has been applied to subcutaneous injection for several therapeutic proteins, such as IL-2 and IFN-alpha(2b), in animal models (rats, dogs, monkeys) and clinical trials in renal cancer (IL-2) and hepatitis C (IFN-alpha(2b)) patients.

  4. Collagen scaffolds with controlled insulin release and controlled pore structure for cartilage tissue engineering.

    Science.gov (United States)

    Nanda, Himansu Sekhar; Chen, Shangwu; Zhang, Qin; Kawazoe, Naoki; Chen, Guoping

    2014-01-01

    Controlled and local release of growth factors and nutrients from porous scaffolds is important for maintenance of cell survival, proliferation, and promotion of tissue regeneration. The purpose of the present research was to design a controlled release porous collagen-microbead hybrid scaffold with controlled pore structure capable of releasing insulin for application to cartilage tissue regeneration. Collagen-microbead hybrid scaffold was prepared by hybridization of insulin loaded PLGA microbeads with collagen using a freeze-drying technique. The pore structure of the hybrid scaffold was controlled by using preprepared ice particulates having a diameter range of 150-250 μ m. Hybrid scaffold had a controlled pore structure with pore size equivalent to ice particulates and good interconnection. The microbeads showed an even spatial distribution throughout the pore walls. In vitro insulin release profile from the hybrid scaffold exhibited a zero order release kinetics up to a period of 4 weeks without initial burst release. Culture of bovine articular chondrocytes in the hybrid scaffold demonstrated high bioactivity of the released insulin. The hybrid scaffold facilitated cell seeding and spatial cell distribution and promoted cell proliferation.

  5. Collagen Scaffolds with Controlled Insulin Release and Controlled Pore Structure for Cartilage Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Himansu Sekhar Nanda

    2014-01-01

    Full Text Available Controlled and local release of growth factors and nutrients from porous scaffolds is important for maintenance of cell survival, proliferation, and promotion of tissue regeneration. The purpose of the present research was to design a controlled release porous collagen-microbead hybrid scaffold with controlled pore structure capable of releasing insulin for application to cartilage tissue regeneration. Collagen-microbead hybrid scaffold was prepared by hybridization of insulin loaded PLGA microbeads with collagen using a freeze-drying technique. The pore structure of the hybrid scaffold was controlled by using preprepared ice particulates having a diameter range of 150–250 μm. Hybrid scaffold had a controlled pore structure with pore size equivalent to ice particulates and good interconnection. The microbeads showed an even spatial distribution throughout the pore walls. In vitro insulin release profile from the hybrid scaffold exhibited a zero order release kinetics up to a period of 4 weeks without initial burst release. Culture of bovine articular chondrocytes in the hybrid scaffold demonstrated high bioactivity of the released insulin. The hybrid scaffold facilitated cell seeding and spatial cell distribution and promoted cell proliferation.

  6. Voltage-Responsive Controlled Release Film with Cargo Release Self-Monitoring Property Based on Hydrophobicity Switching.

    Science.gov (United States)

    Jiao, Xiangyu; Li, Yanan; Li, Fengyu; Sun, Ruijuan; Wang, Wenqian; Wen, Yongqiang; Song, Yanlin; Zhang, Xueji

    2017-03-16

    Herein, voltage-responsive controlled release film was constructed by grafting ferrocene on the mesoporous inverse opal photonic crystal (mIOPC). The film achieved free-blockage controlled release and realized the monitoring of cargo release without external indicator. Free-blockage was attributed to the voltage switchable nanovalves which undergo hydrophobic-to-hydrophilic transition when applying voltage. Monitoring of cargo release was attributed to the optical property of mIOPC, the bandgap of mIOPC had a red shift when the solution invaded in. The film was hydrophobic enough to stop solution intrusion. Once the voltage was applied, the film became hydrophilic, leading to invasion of the solution. As a result, the cargos were released and the bandgap of mIOPC was red-shifted. Therefore, in this paper both a free-blockage controlled release film and a release sensing system was prepared. The study provides new insights into highly effective controlled release and release sensing without indicator.

  7. [Effects of applying controlled-release compound fertilizer on Platycodon grandiflorum growth].

    Science.gov (United States)

    Zhu, Li-xiang; Wang, Jian-hua

    2010-09-01

    A pot experiment was conducted in 2008 to study the effects of applying controlled-release compound fertilizer (N:P2O5:K2O = 14:14:14) on the growth of Platycodon grandiflorum in the medicinal herbal farm of Shandong Agricultural University. Comparing with the application of common compound fertilizer (N:P2O5: K2O=15: 15: 15), applying equivalent amount of the controlled-release fertilizer increased the leaf chlorophyll content, root volume, root activity, and root diameter of P. grandiflorum at the late growth stage, but decreased the root length. When the N application rate was 0.24 and 0.32 g x kg(-1) soil, applying the controlled-release compound fertilizer increased the root yield by 26.78% and 22.50%, and the root soluble sugar, protein, and total saponin contents by 9.77% and 6.99%, 11.38% and 2.20%, and 8.85% and 5.47%, respectively, compared with applying the common compound fertilizer. More nitrogen application made the root soluble sugar content decreased but the total saponin content increased. Under our experimental condition, applying the controlled-release compound fertilizer with an application rate of 0.24 g N x kg(-1) soil could obtain the best effect for P. grandiflorum.

  8. [Advances in effects of insecticidal crystal proteins released from transgenic Bt crops on soil ecology].

    Science.gov (United States)

    Zhou, Xue-Yong; Liu, Ning; Zhao, Man; Li, He; Zhou, Lang; Tang, Zong-Wen; Cao, Fei; Li, Wei

    2011-05-01

    With the large scale cultivation of transgenic crops expressing Bacillus thuringiensis (Bt) insecticidal crystal proteins in the world, the problem of environmental safety caused by these Bt crops has received extensive attention. These insecticidal crystal proteins can be released into the soil continuously in the growing period of Bt plants. If their accumulation of the insecticidal crystal proteins exceeds consumption by insect larvae and degradation by the environmental factors, these insecticidal crystal proteins could constitute a hazard to non-target insects and soil microbiota. There are three main ways to release insecticidal crystal proteins into soil for Bt plants: root exudates, pollen falling, and crop reside returning. The Bt insecticidal crystal proteins released into soil can be adsorbed rapidly by active soil particles and the absorption equilibrium attained within 1-3 h. The adsorption protects Bt insecticidal crystal proteins against soil microbial degradation or enzyme degradation, which leads to remarkable prolong of the persistence of insecticidal activity. The change of soil microorganism species is an important index for evaluating the effect of Bt plants on soil ecology. The research showed that these insecticidal crystal proteins released by the Bt plant root exudates or Bt organism had no toxicity to the soil earthworms, nematodes, protozoa, bacteria and fungi; however, it could reduce the mycelium length of the arbuscular mycorrhizal fungi (AMF) and restrain AMF to form invasion unit. The influencing degree of Bt protein on soil enzyme activity varied with the releasing modes or growth period of Bt crops. Bt Cry1Ab protein can be taken up from soil by parts of following crops; however, different results were obtained with different commercial kits. To better understand the soil ecological evaluation about the insecticidal crystal proteins released from transgenic Bt crops, this review provides a comprehensive overview about the release

  9. Temporally controlled release of multiple growth factors from a self-assembling peptide hydrogel

    Science.gov (United States)

    Bruggeman, Kiara F.; Rodriguez, Alexandra L.; Parish, Clare L.; Williams, Richard J.; Nisbet, David R.

    2016-09-01

    Protein growth factors have demonstrated great potential for tissue repair, but their inherent instability and large size prevents meaningful presentation to biologically protected nervous tissue. Here, we create a nanofibrous network from a self-assembling peptide (SAP) hydrogel to carry and stabilize the growth factors. We significantly reduced growth factor degradation to increase their lifespan by over 40 times. To control the temporal release profile we covalently attached polysaccharide chitosan molecules to the growth factor to increase its interactions with the hydrogel nanofibers and achieved a 4 h delay, demonstrating the potential of this method to provide temporally controlled growth factor delivery. We also describe release rate based analysis to examine the growth factor delivery in more detail than standard cumulative release profiles allow and show that the chitosan attachment method provided a more consistent release profile with a 60% reduction in fluctuations. To prove the potential of this system as a complex growth factor delivery platform we demonstrate for the first time temporally distinct release of multiple growth factors from a single tissue specific SAP hydrogel: a significant goal in regenerative medicine.

  10. Release behavior of non-network proteins and its relationship to the structure of heat-induced soy protein gels.

    Science.gov (United States)

    Wu, Chao; Hua, Yufei; Chen, Yeming; Kong, Xiangzhen; Zhang, Caimeng

    2015-04-29

    Heat-induced soy protein gels were prepared by heating protein solutions at 12%, 15% ,or 18% for 0.5, 1.0, or 2.0 h. The release of non-network proteins from gel slices was conducted in 10 mM pH 7.0 sodium phosphate buffer. SDS-PAGE and diagonal electrophoresis demonstrated that the released proteins consisted of undenatured AB subunits and denatured proteins including monomers of A polypeptides, disulfide bond linked dimers, trimers, and polymers of A polypeptides, and an unidentified 15 kDa protein. SEC-HPLC analysis of non-network proteins revealed three major protein peaks, with molecular weights of approximately 253.9, 44.8, and 9.7 kDa. The experimental data showed that the time-dependent release of the three fractions from soy protein gels fit Fick's second law. An increasing protein concentration or heating time resulted in a decrease in diffusion coefficients of non-network proteins. A power law expression was used to describe the relationship between non-network protein diffusion coefficient and molecular weight, for which the exponent (α) shifted to higher value with an increase in protein concentration or heating time, indicating that a more compact gel structure was formed.

  11. DEVELOPMENT AND EVALUATION OF CLOZAPINE PELLETS FOR CONTROLLED RELEASE

    Directory of Open Access Journals (Sweden)

    D.V. Gowda

    2012-08-01

    Full Text Available This research work was done to design oral controlled release matrix pellets of water insoluble drug Clozapine, using blend of Hydroxypropyl cellulose and glyceryl palmito stearate as as matrix polymers, methyl crystalline cellulose as spheronizer enhancer,sodium lauryl sulphate as pore forming agent. Clozapine formulations developed by the pellitization technique by drug loaded pellets were characterized with regard to the drug content, size distribution, Scanning electron microscopy, differential scanning calorimetry, fourier transform infrared spectroscopy and Xray Diffraction study. Stability studies were carried out on the optimized formulation for aperiod of 90 days, 40 ± 2 oC and 75 ± 5% relative humidity. The drug content was in the range of 95.34 – 98.12 %. The mean particle size of drug loaded pellets was in the range 1018 to 1065 mm. SEM photographs and calculated sphericity factor confirms that the prepared formulations were spherical in nature. The drug loaded pellets were stable and compatible as confirmed by DSC and FTIR studies. XRD patterns revealed the crystalline nature of pure clozapine. Loose surface crystal study indicated that crystalline clozapine was observed in all formulation and more clear in formulation A5. Higher amount of clozapine released was observed from formulation A5 and Syclop® 25 mg tablet as compared to all other formulations and mechanism of drug release followed Fickian diffusion. It can be concluded that formulation A5 is an ideal formulation for once a day administration.

  12. Combinatorial Synthesis of and high-throughput protein release from polymer film and nanoparticle libraries.

    Science.gov (United States)

    Petersen, Latrisha K; Chavez-Santoscoy, Ana V; Narasimhan, Balaji

    2012-09-06

    Polyanhydrides are a class of biomaterials with excellent biocompatibility and drug delivery capabilities. While they have been studied extensively with conventional one-sample-at-a-time synthesis techniques, a more recent high-throughput approach has been developed enabling the synthesis and testing of large libraries of polyanhydrides(1). This will facilitate more efficient optimization and design process of these biomaterials for drug and vaccine delivery applications. The method in this work describes the combinatorial synthesis of biodegradable polyanhydride film and nanoparticle libraries and the high-throughput detection of protein release from these libraries. In this robotically operated method (Figure 1), linear actuators and syringe pumps are controlled by LabVIEW, which enables a hands-free automated protocol, eliminating user error. Furthermore, this method enables the rapid fabrication of micro-scale polymer libraries, reducing the batch size while resulting in the creation of multivariant polymer systems. This combinatorial approach to polymer synthesis facilitates the synthesis of up to 15 different polymers in an equivalent amount of time it would take to synthesize one polymer conventionally. In addition, the combinatorial polymer library can be fabricated into blank or protein-loaded geometries including films or nanoparticles upon dissolution of the polymer library in a solvent and precipitation into a non-solvent (for nanoparticles) or by vacuum drying (for films). Upon loading a fluorochrome-conjugated protein into the polymer libraries, protein release kinetics can be assessed at high-throughput using a fluorescence-based detection method (Figures 2 and 3) as described previously(1). This combinatorial platform has been validated with conventional methods(2) and the polyanhydride film and nanoparticle libraries have been characterized with (1)H NMR and FTIR. The libraries have been screened for protein release kinetics, stability and

  13. Controlled growth factor release from synthetic extracellular matrices

    Science.gov (United States)

    Lee, Kuen Yong; Peters, Martin C.; Anderson, Kenneth W.; Mooney, David J.

    2000-12-01

    Polymeric matrices can be used to grow new tissues and organs, and the delivery of growth factors from these matrices is one method to regenerate tissues. A problem with engineering tissues that exist in a mechanically dynamic environment, such as bone, muscle and blood vessels, is that most drug delivery systems have been designed to operate under static conditions. We thought that polymeric matrices, which release growth factors in response to mechanical signals, might provide a new approach to guide tissue formation in mechanically stressed environments. Critical design features for this type of system include the ability to undergo repeated deformation, and a reversible binding of the protein growth factors to polymeric matrices to allow for responses to repeated stimuli. Here we report a model delivery system that can respond to mechanical signalling and upregulate the release of a growth factor to promote blood vessel formation. This approach may find a number of applications, including regeneration and engineering of new tissues and more general drug-delivery applications.

  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.

  15. Evaluation of a soil incubation method to characterize nitrogen release patterns of slow- and controlled-release fertilizers.

    Science.gov (United States)

    Medina, L Carolina; Sartain, Jerry B; Obreza, Thomas A; Hall, William L; Thiex, Nancy J

    2014-01-01

    Several technologies have been proposed to characterize the nutrient release patterns of slow-release fertilizers (SRF) and controlled-release fertilizers (CRF) during the last few decades. These technologies have been developed mainly by manufacturers, and are product-specific, based on the regulation and analysis of each SRF and CRF product. Despite previous efforts to characterize SRF and CRF materials, no standardized, validated method exists to assess their nutrient release patterns. However, the increased production and distribution of these materials in specialty and nonspecialty markets requires an appropriate method to verify product claims and material performance. A soil incubation column leaching procedure was evaluated to determine its suitability as a standard method to estimate nitrogen (N) release patterns of SRFs and CRFs during 180 days. The influence of three soil/sand ratios, three incubation temperatures, and four soils on method behavior was assessed using five SRFs and three CRFs. In general, the highest soil/sand ratio increased the N release rate of all materials, but this effect was more marked for the SRFs. Temperature had the greatest influence on N release rates. For CRFs, the initial N release rates and the percentage N released/day increased as temperature increased. For SRFs, raising the temperature from 25 to 35 degreesC increased initial N release rate and the total cumulative N released, and almost doubled the percentage released/day. The percentage N released/day from all products generally increased as the texture of the soil changed from sandy to loamy (lowa>California>Pennsylvania>Florida). The soil incubation technique was demonstrated to be robust and reliable for characterizing N release patterns from SRFs and CRFs. The method was reproducible, and variations in soil/sand ratio, temperature, and soil had little effect on the results.

  16. Controlled iodine release from polyurethane sponges for water decontamination.

    Science.gov (United States)

    Aviv, Oren; Laout, Natalia; Ratner, Stanislav; Harik, Oshrat; Kunduru, Konda Reddy; Domb, Abraham J

    2013-12-28

    Iodinated polyurethane (IPU) sponges were prepared by immersing sponges in aqueous/organic solutions of iodine or exposing sponges to iodine vapors. Iodine was readily adsorbed into the polymers up to 100% (w/w). The adsorption of iodine on the surface was characterized by XPS and SEM analyses. The iodine loaded IPU sponges were coated with ethylene vinyl acetate (EVA), in order to release iodine in a controlled rate for water decontamination combined with active carbon cartridge, which adsorbs the iodine residues after the microbial inactivation. The EVA coated IPU were incorporated in a water purifier and tested for iodine release to water and for microbial inactivation efficiency according to WQA certification program against P231/EPA for 250l, using 25l a day with flow rate of 6-8min/1l. The antimicrobial activity was also studied against Escherichia coli and MS2 phage. Bacterial results exceeded the minimal requirement for bacterial removal of 6log reduction throughout the entire lifespan. At any testing point, no bacteria was detected in the outlet achieving more than 7.1 to more than 8log reduction as calculated upon the inlet concentration. Virus surrogate, MS2, reduction results varied from 4.11log reduction under tap water, and 5.11log reduction under basic water (pH9) to 1.32 for acidic water (pH5). Controlled and stable iodine release was observed with the EVA coated IPU sponges and was effective in deactivating the bacteria and virus present in the contaminated water and thus, these iodinated PU systems could be used in water purification to provide safe drinking water. These sponges may find applications as disinfectants in medicine.

  17. Influence of alcohol on the release of tramadol from 24-h controlled-release formulations during in vitro dissolution experiments.

    Science.gov (United States)

    Traynor, M J; Brown, M B; Pannala, A; Beck, P; Martin, G P

    2008-08-01

    Recent warnings by regulatory bodies and a product recall by the FDA have generated much interest in the area of dose dumping from controlled-release opioid analgesic formulations when coingested with alcohol. It was the aim of this study to address this issue and in doing so, gain understanding on how alcohol-induced effects may be avoided. In this study, tramadol release from Ultram ER tablets and T-long capsules was significantly increased in the presence of ethanol. Conversely, a decrease in the rate of tramadol release was seen from Tridural extended-release tablets in the presence of alcohol.

  18. 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.

  19. 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

    2016-12-01

    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.

  20. 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

  1. 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.

  2. Modeling controlled nutrient release from a population of polymer coated fertilizers: statistically based model for diffusion release.

    Science.gov (United States)

    Shaviv, Avi; Raban, Smadar; Zaidel, Elina

    2003-05-15

    A statistically based model for describing the release from a population of polymer coated controlled release fertilizer (CRF) granules by the diffusion mechanism was constructed. The model is based on a mathematical-mechanistic description of the release from a single granule of a coated CRF accounting for its complex and nonlinear nature. The large variation within populations of coated CRFs poses the need for a statistically based approach to integrate over the release from the individual granules within a given population for which the distribution and range of granule radii and coating thickness are known. The model was constructed and verified using experimentally determined parameters and release curves of polymer-coated CRFs. A sensitivity analysis indicated the importance of water permeability in controlling the lag period and that of solute permeability in governing the rate of linear release and the total duration of the release. Increasing the mean values of normally distributed granule radii or coating thickness, increases the lag period and the period of linear release. The variation of radii and coating thickness, within realistic ranges, affects the release only when the standard deviation is very large or when water permeability is reduced without affecting solute permeability. The model provides an effective tool for designing and improving agronomic and environmental effectiveness of polymer-coated CRFs.

  3. Effects of Control Release Fertilizers on Nutrient Leaching, Palm Growth and Production Cost

    OpenAIRE

    Pushpa Soti; Angie Fleurissaint; Stewart Reed; Krish Jayachandran

    2015-01-01

    Objective of this study was to evaluate the effect of different controlled release fertilizer technologies on nutrient leaching and plant growth parameters of two palm species, Chinese Fan (Livistona chinensis) and Queen (Syagrus romanzoffiana). We compared Nutri-Pak (12-4-12 controlled release packet) and Harrell’s (12-4-12 controlled release polymer coated urea) against Atlantic (8-4-12 controlled release polymer coated urea, coated sulfate of potash), the most commonly used palm fertilize...

  4. Complex viscosity induced by protein composition variation influences the aroma release of flavored stirred yogurt.

    Science.gov (United States)

    Saint-Eve, Anne; Juteau, Alexandre; Atlan, Samuel; Martin, Nathalie; Souchon, Isabelle

    2006-05-31

    Dairy protein composition is known to influence the structure and the texture characteristics of yogurt. The objective of the present work was therefore to investigate the impact of protein composition, at a constant protein level, on the physicochemical properties of 4% fat flavored stirred yogurt and, more specifically, on the rheological properties, the microstructure, and the aroma release. The results showed that caseinate-enriched yogurt generally presented changes in their microstructure network and had a higher complex viscosity than whey protein-enriched yogurt. To a lesser extent, the release of the majority of aroma compounds was lower in caseinate-enriched yogurt. It was therefore possible to quantify physicochemical interactions between aroma compounds and proteins. The influence of gel structure on the flavor release was observed and was in agreement with sensory characteristics previously studied for these products.

  5. NLP-12 engages different UNC-13 proteins to potentiate tonic and evoked release.

    Science.gov (United States)

    Hu, Zhitao; Vashlishan-Murray, Amy B; Kaplan, Joshua M

    2015-01-21

    A neuropeptide (NLP-12) and its receptor (CKR-2) potentiate tonic and evoked ACh release at Caenorhabditis elegans neuromuscular junctions. Increased evoked release is mediated by a presynaptic pathway (egl-30 Gαq and egl-8 PLCβ) that produces DAG, and by DAG binding to short and long UNC-13 proteins. Potentiation of tonic ACh release persists in mutants deficient for egl-30 Gαq and egl-8 PLCβ and requires DAG binding to UNC-13L (but not UNC-13S). Thus, NLP-12 adjusts tonic and evoked release by distinct mechanisms.

  6. Electrospinning of Cross-Linked Magnetic Chitosan Nanofibers for Protein Release.

    Science.gov (United States)

    Nicknejad, Ehsan Tayerani; Ghoreishi, Seyyed Mohammad; Habibi, Neda

    2015-12-01

    A poly(vinylalcohol) (PVA) electrospun/magnetic/chitosan nanocomposite fibrous cross-linked network was fabricated using in situ cross-linking electrospinning technique and used for bovine serum albumin (BSA) loading and release applications. Sodium tripolyphosphate (TPP) and glutaraldehyde (GA) were used as cross-linkers which modified magnetic-Fe3O4 chitosan as Fe3O4/CS/TPP and Fe3O4/CS/GA, respectively. BSA was used as a model protein drugs which was encapsulated to form Fe3O4/CS/TPP/BSA and Fe3O4/CS/GA/BSA nanoparticles. The composites were electrospun with PVA to form nanofibers. Nanofibers were characterized by field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR). The characterization results suggest that Fe3O4 nanoparticles with average size of 45 nm were successfully bound on the surface of chitosan. The cross-linked nanofibers were found to contain uniformly dispersed Fe3O4 nanoparticles. The size and morphology of the nanofibers network was controlled by varying the cross-linker type. FTIR data show that these two polymers have intermolecular interactions. The sample with TPP cross-linker showed an enhancement of the controlled release properties of BSA during 30-h experimental investigation. Graphical Abstract ᅟ.

  7. Thermal post-treatment alters nutrient release from a controlled-release fertilizer coated with a waterborne polymer

    OpenAIRE

    Zijun Zhou; Changwen Du; Ting Li; Yazhen Shen; Jianmin Zhou

    2015-01-01

    Controlled-release fertilizers (CRF) use a controlled-release technology to enhance the nutrient use efficiency of crops. Many factors affect the release of nutrients from the waterborne polymer-coated CRF, but the effects of thermal post-treatments remain unclear. In this study, a waterborne polyacrylate-coated CRF was post-treated at different temperatures (30 °C, 60 °C, and 80 °C) and durations (2, 4, 8, 12, and 24 h) after being developed in the Wurster fluidized bed. To characterize the ...

  8. Thermal post-treatment alters nutrient release from a controlled-release fertilizer coated with a waterborne polymer

    OpenAIRE

    Zijun Zhou; Changwen Du; Ting Li; Yazhen Shen; Jianmin Zhou

    2015-01-01

    Controlled-release fertilizers (CRF) use a controlled-release technology to enhance the nutrient use efficiency of crops. Many factors affect the release of nutrients from the waterborne polymer-coated CRF, but the effects of thermal post-treatments remain unclear. In this study, a waterborne polyacrylate-coated CRF was post-treated at different temperatures (30 °C, 60 °C, and 80 °C) and durations (2, 4, 8, 12, and 24 h) after being developed in the Wurster fluidized bed. To characterize the ...

  9. Mammalian carboxylesterase (CES) releases GPI-anchored proteins from the cell surface upon lipid raft fluidization.

    Science.gov (United States)

    Orihashi, Kaoru; Tojo, Hiromasa; Okawa, Katsuya; Tashima, Yuko; Morita, Takashi; Kondoh, Gen

    2012-03-01

    Mammalian carboxylesterase (CES) is well known as a biotransformation enzyme for prodrugs and xenobiotics. Here, we purified CES as a GPI-anchored protein (GPI-AP)-releasing factor (GPIase) that releases such protein from the cell surface. All five isoforms of CES showed this activity to various degrees. When the serine residue of the catalytic triad for esterase was replaced by alanine, esterase activity was completely disrupted, while full GPIase activity remained, suggesting that these two activities are exhibited via different mechanisms. CES6, a new class of mammalian CES, exhibited the highest GPIase activity and released specific GPI-APs from the cell surface after lipid raft fluidization. The released product contained a GPI component, indicating that GPI-AP was released by cleavage in GPI. These results revealed for the first time that CES recognizes and catalyzes macromolecule GPI-AP as well as small molecules.

  10. Double walled POE/PLGA microspheres: encapsulation of water-soluble and water-insoluble proteins and their release properties.

    Science.gov (United States)

    Shi, Meng; Yang, Yi-Yan; Chaw, Cheng-Shu; Goh, Suat-Hong; Moochhala, Shabbir M; Ng, Steve; Heller, Jorge

    2003-04-29

    The poly(orthoester) (POE)-poly(D,L-lactide-co-glycolide) (50:50) (PLGA) double-walled microspheres with 50% POE in weight were loaded with hydrophilic bovine serum albumin (BSA) and hydrophobic cyclosporin A (CyA). Most of the BSA and CyA was entrapped within the shell and core, respectively, because of the difference in their hydrophilicity. The morphologies and release mechanisms of proteins-loaded double-walled POE/PLGA microspheres were investigated. Scanning electron microscope studies revealed that the CyA-BSA-loaded double-walled POE/PLGA microspheres yielded a more porous surface and PLGA shell than those without BSA. The neat POE and PLGA yielded slow and incomplete CyA and BSA release. In contrast, nearly complete BSA and more than 95% CyA were released in a sustained manner from the double-walled POE/PLGA microspheres. Both the BSA- and CyA-BSA-loaded POE/PLGA microspheres yielded a sustained BSA release over 5 days. The CyA release pattern of the CyA-loaded double-walled POE/PLGA microspheres was biphasic, characterized by a slow release over 15 days followed by a sustained release over 27 days. However, the CyA-BSA-loaded double-walled POE/PLGA microspheres provided a more constant and faster CyA release due to their more porous shell. In the CyA-BSA-loaded double-walled POE/PLGA microspheres system, the PLGA layer acted as a carrier for BSA and mild reservoir for CyA. During the first 5 days, most BSA was released from the shell but only 14% CyA was left from the microspheres. Subsequently, more than 80% CyA were released in the next 25 days. The distinct structure of double-walled POE/PLGA microspheres would make an interesting device for controlled delivery of therapeutic agents.

  11. Controlled release of human growth hormone fused with a human hybrid Fc fragment through a nanoporous polymer membrane

    Science.gov (United States)

    Kim, Eung-Sam; Jang, Do Soo; Yang, Seung Yun; Lee, Mi Nam; Jin, Kyeong Sik; Cha, Hyung Jin; Kim, Jin Kon; Sung, Young Chul; Choi, Kwan Yong

    2013-05-01

    Nanotechnology has been applied to the development of more effective and compatible drug delivery systems for therapeutic proteins. Human growth hormone (hGH) was fused with a hybrid Fc fragment containing partial Fc domains of human IgD and IgG4 to produce a long-acting fusion protein. The fusion protein, hGH-hyFc, resulted in the increase of the hydrodynamic diameter (ca. 11 nm) compared with the diameter (ca. 5 nm) of the recombinant hGH. A diblock copolymer membrane with nanopores (average diameter of 14.3 nm) exhibited a constant release rate of hGH-hyFc. The hGH-hyFc protein released in a controlled manner for one month was found to trigger the phosphorylation of Janus kinase 2 (JAK2) in human B lymphocyte and to exhibit an almost identical circular dichroism spectrum to that of the original hGH-hyFc, suggesting that the released fusion protein should maintain the functional and structural integrity of hGH. Thus, the nanoporous release device could be a potential delivery system for the long-term controlled release of therapeutic proteins fused with the hybrid Fc fragment.Nanotechnology has been applied to the development of more effective and compatible drug delivery systems for therapeutic proteins. Human growth hormone (hGH) was fused with a hybrid Fc fragment containing partial Fc domains of human IgD and IgG4 to produce a long-acting fusion protein. The fusion protein, hGH-hyFc, resulted in the increase of the hydrodynamic diameter (ca. 11 nm) compared with the diameter (ca. 5 nm) of the recombinant hGH. A diblock copolymer membrane with nanopores (average diameter of 14.3 nm) exhibited a constant release rate of hGH-hyFc. The hGH-hyFc protein released in a controlled manner for one month was found to trigger the phosphorylation of Janus kinase 2 (JAK2) in human B lymphocyte and to exhibit an almost identical circular dichroism spectrum to that of the original hGH-hyFc, suggesting that the released fusion protein should maintain the functional and

  12. Midgut proteins released by microapocrine secretion in Spodoptera frugiperda.

    Science.gov (United States)

    Silva, Walciane; Cardoso, Christiane; Ribeiro, Alberto F; Terra, Walter R; Ferreira, Clélia

    2013-01-01

    Microapocrine vesicles bud from the lepidopteran midgut microvilli as double membrane vesicles. To identify the proteins secreted by this process, antibodies raised against isolated microapocrine vesicles from Spodoptera frugiperda were used for screening a midgut cDNA expression library. Positive clones were sequenced, assembled and N blasted against S. frugiperda sequences obtained by pyrosequencing midgut mRNA. This procedure led to the extension of microapocrine sequences that were annotated. A similar procedure was used to identify midgut microvillar proteins that necessarily are part of the microapocrine vesicle. Forty-eight proteins were associated with microvillar membranes. They pertain to 8 functional groups: digestive enzymes, peritrophic membrane, protection, transporters, receptors, secretory machinery, cytoskeleton and signaling, and unknown. Twenty-eight proteins are putatively secreted by microapocrine secretion. Most of them are digestive enzymes, but the list also includes proteins involved in protection and in peritrophic membrane formation. Among the identified digestive enzymes, aminopeptidases are typically microvillar and group into the classes 1, 2, 3, 5, and 6. There are two amylases secreted by microapocrine secretion: one is a digestive enzyme and the other is a transporter-like amylase with no clear function. One lipase has a predicted transmembrane loop, whereas the others are supposed to be secreted by microapocrine secretion and be digestive. Trypsin is membrane bound and is delivered by microapocrine secretion, but has no predicted features to bind membranes. It may remain bound through the signal peptide till be delivered into the midgut lumen. Proteins supposed to be involved in the microapocrine secretory machinery were: calmodulin, annexin, myosin 7a, and gelsolin 1. Their putative roles are discussed, but more research is necessary to settle this subject.

  13. Role of protein kinase C in histamine release from human basophils.

    Science.gov (United States)

    Morita, Y; Takaishi, T; Honda, Z; Miyamoto, T

    1988-02-01

    In this study, we investigated the role of calcium and phospholipid-dependent protein kinase (protein kinase C, PKC) in the modulation of histamine release from human basophils. A novel and potent inhibitor of PKC, K-252a, inhibited the release of histamine induced by anti-IgE in a dose-dependent manner with ID50 (the dose required for 50% inhibition of histamine release) of 2.2 x 10(-8) M. Histamine release stimulated with 12-0-tetradecanoyl-phorbol-13-acetate(TPA) was also suppressed by K-252a with maximal inhibition of 48.0 +/- 9.3% at 10(-7) M. In contrast, K-252a did not inhibit the release of histamine in response to FMLP and ionophore A23187. Another inhibitor of PKC, H-7, exhibited a dose-dependent inhibition of anti-IgE-induced histamine release with ID50 of 8.6 x 10(-4) M. H-8 and HA1004, which closely resemble H-7 in chemical structure but are less potent in inhibiting PKC, did not inhibit histamine release stimulated with anti-IgE, but rather enhanced the release at higher concentrations. These results strongly suggest that PKC activation plays a crucial role in the mediation of IgE-mediated histamine release from human basophils.

  14. Oral suspensions of morphine hydrochloride for controlled release: rheological properties and drug release.

    Science.gov (United States)

    Morales, M E; López, G; Gallardo, V; Ruiz, M A

    2011-04-04

    Recent developments in pharmaceutical technology have facilitated the design and production of modified release formulas for drugs whose physical, chemical or biological properties impede release and thus might compromise their efficacy or safety. One such drug is morphine, whose short half-life requires repeated doses at short intervals. The use of biocompatible polymers such as ethylcellulose has made it possible to develop microencapsulated formulations which facilitate liquid, sustained-release pharmaceutical formulas for oral administration. We developed a stable final formulation of morphine with an acceptable release profile by comparing the rheological properties and stability of formulations with different thickeners (xanthan gum, Carbopol, and carboxymethylcellulose with microcrystalline cellulose) at different concentrations from 0.25% to 1.0%. Release assays in a Franz-type cell were done to determine the most suitable release profile for the formulation.

  15. Properties and controlled release of chitosan microencapsulated limonene oil

    Directory of Open Access Journals (Sweden)

    Jefferson M. Souza

    2014-12-01

    Full Text Available Chitosan microcapsules containing limonene essential oil as active ingredient were prepared by coacervation using three different concentrations of NaOH (0.50, 1.00, 1.45 wt% and fixed concentrations of chitosan and surfactant of 0.50 wt%. The produced microcapsules were fully characterized in their morphology and chemical composition, and the kinetic release analysis of the active ingredient was evaluated after deposition in a non-woven cellulose fabric. The concentration of 1.00 and 1.45 wt% clearly show the best results in terms of dimension and shape of the microcapsules as well as in the volatility results. However, at the concentration of 1 wt% a higher number of microcapsules were produced as confirmed by FTIR and EDS analysis. Free microcapsules are spherical in size with disperse diameters between 2 and 12 μm. Immobilized microcapsules showed sizes from 4 to 7 μm, a rough surface and loss of spherical shape with pore formation in the chitosan walls. SEM analysis confirms that at higher NaOH concentrations, the larger the size of the microcapsules. This technique shows that by tuning NaOH concentration it is possible to efficiently control the release rate of encapsulated active agents demonstrating great potential as insect repellent for textiles.

  16. Diurnal rhythm in expression and release of yolk protein in the testis of Spodoptera littoralis (Lepidoptera: Noctuidae).

    Science.gov (United States)

    Kotwica, Joanna; Joachimiak, Ewa; Polanska, Marta A; Majewska, Magdalena M; Giebultowicz, Jadwiga M; Bebas, Piotr

    2011-04-01

    Circadian clocks (oscillators) regulate multiple life functions in insects. The circadian system located in the male reproductive tract of Lepidoptera is one of the best characterized peripheral oscillators in insects. Our previous research on the cotton leafworm, Spodoptera littoralis, demonstrated that this oscillator controls the rhythm of sperm release from the testis and coordinates sperm maturation in the upper vas deferens (UVD). We demonstrated previously that a protein that functions as yolk protein in females is also produced in cyst cells surrounding sperm bundles in the testis, and is released into the UVD. Here, we investigated the temporal expression of the yolk protein 2 (yp2) gene at the mRNA and protein level in the testis of S. littoralis, and inquired whether their expression is regulated by PER-based molecular oscillator. We describe a circadian rhythm of YP2 accumulation in the UVD seminal fluid, where this protein interacts with sperm in a circadian fashion. However, we also demonstrate that yp2 mRNA and YP2 protein levels within cyst cells show only a diurnal rhythm in light/dark (LD) cycles. These rhythms do not persist in constant darkness (DD), suggesting that they are non-circadian. Interestingly, the per gene mRNA and protein levels in cyst cells are rhythmic in LD but not in DD. Nevertheless, per appears to be involved in the diurnal timing of YP2 protein accumulation in cyst cells.

  17. Hydrogels of collagen-inspired telechelic triblock copolymers for the sustained release of proteins

    NARCIS (Netherlands)

    Teles, H.M.; Vermonden, T.; Eggink, G.

    2010-01-01

    We studied the release of entrapped protein from transient gels made of thermosensitive, collagen-inspired ABA triblock copolymers with tailorable properties and with mid blocks of two different lengths (~ 37 kDa and ~ 73 kDa). These polymers were produced as heterologous proteins in recombinant yea

  18. 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.

  19. Azotobacter vinelandii metal storage protein: "classical" inorganic chemistry involved in Mo/W uptake and release processes.

    Science.gov (United States)

    Schemberg, Jörg; Schneider, Klaus; Fenske, Dirk; Müller, Achim

    2008-03-03

    The release of Mo (as molybdate) from the Mo storage protein (MoSto), which is unique among all existing metalloproteins, is strongly influenced by temperature and pH value; other factors (incubation time, protein concentration, degree of purity) have minor, though significant effects. A detailed pH titration at 12 degrees C revealed that three different steps can be distinguished for the Mo-release process. A proportion of approximately 15% at pH 6.8-7.0, an additional 25% at pH 7.2-7.5 and ca. 50% (up to 90% in total) at pH 7.6-7.8. This triphasic process supports the assumption of the presence of different types of molybdenum-oxide-based clusters that exhibit different pH lability. The complete release of Mo was achieved by increasing the temperature to 30 degrees C and the pH value to >7.5. The Mo-release process does not require ATP; on the contrary, ATP prevents, or at least reduces the degree of metal release, depending on the concentration of the nucleotide. From this point of view, the intracellular ATP concentration is suggested to play-in addition to the pH value-an indirect but crucial role in controlling the extent of Mo release in the cell. The binding of molybdenum to the apoprotein (reconstitution process) was confirmed to be directly dependent on the presence of a nucleotide (preferably ATP) and MgCl2. Maximal reincorporation of Mo required 1 mM ATP, which could partly be replaced by GTP. When the storage protein was purified in the presence of ATP and MgCl2 (1 mM each), the final preparation contained 80 Mo atoms per protein molecule. Maximal metal loading (110-115 atoms/MoSto molecule) was only achieved, if Mo was first completely released from the native protein and subsequently (re-) bound under optimal reconstitution conditions: 1 h incubation at pH 6.5 and 12 degrees C in the presence of ATP, MgCl2 and excess molybdate. A corresponding tungsten-containing storage protein ("WSto") could not only be synthesized in vivo by growing cells, but

  20. Adsorption and protein-induced metal release from chromium metal and stainless steel.

    Science.gov (United States)

    Lundin, M; Hedberg, Y; Jiang, T; Herting, G; Wang, X; Thormann, E; Blomberg, E; Wallinder, I Odnevall

    2012-01-15

    A research effort is undertaken to understand the mechanism of metal release from, e.g., inhaled metal particles or metal implants in the presence of proteins. The effect of protein adsorption on the metal release process from oxidized chromium metal surfaces and stainless steel surfaces was therefore examined by quartz crystal microbalance with energy dissipation monitoring (QCM-D) and graphite furnace atomic absorption spectroscopy (GFAAS). Differently charged and sized proteins, relevant for the inhalation and dermal exposure route were chosen including human and bovine serum albumin (HSA, BSA), mucin (BSM), and lysozyme (LYS). The results show that all proteins have high affinities for chromium and stainless steel (AISI 316) when deposited from solutions at pH 4 and at pH 7.4 where the protein adsorbed amount was very similar. Adsorption of albumin and mucin was substantially higher at pH 4 compared to pH 7.4 with approximately monolayer coverage at pH 7.4, whereas lysozyme adsorbed in multilayers at both investigated pH. The protein-surface interaction was strong since proteins were irreversibly adsorbed with respect to rinsing. Due to the passive nature of chromium and stainless steel (AISI 316) surfaces, very low metal release concentrations from the QCM metal surfaces in the presence of proteins were obtained on the time scale of the adsorption experiment. Therefore, metal release studies from massive metal sheets in contact with protein solutions were carried out in parallel. The presence of proteins increased the extent of metals released for chromium metal and stainless steel grades of different microstructure and alloy content, all with passive chromium(III)-rich surface oxides, such as QCM (AISI 316), ferritic (AISI 430), austentic (AISI 304, 316L), and duplex (LDX 2205).

  1. Influence of olive oil phenolic compounds on headspace aroma release by interaction with whey proteins.

    Science.gov (United States)

    Genovese, Alessandro; Caporaso, Nicola; De Luca, Lucia; Paduano, Antonello; Sacchi, Raffaele

    2015-04-22

    The release of volatile compounds in an oil-in-water model system obtained from olive oil-whey protein (WP) pairing was investigated by considering the effect of phenolic compounds. Human saliva was used to simulate mouth conditions by retronasal aroma simulator (RAS) analysis. Twelve aroma compounds were quantified in the dynamic headspace by SPME-GC/MS. The results showed significant influences of saliva on the aroma release of virgin olive oil (VOO) volatiles also in the presence of WP. The interaction between WP and saliva leads to lower headspace release of ethyl esters and hexanal. Salivary components caused lower decrease of the release of acetates and alcohols. A lower release of volatile compounds was found in the RAS essay in comparison to that in orthonasal simulation of only refined olive oil (without addition of saliva or WP), with the exception of hexanal and 1-penten-3-one, where a significantly higher release was found. Our results suggest that the extent of retronasal odor (green, pungent) of these two volatile compounds is higher than orthonasal odor. An extra VOO was used to verify the release in model systems, indicating that WP affected aroma release more than model systems, while saliva seems to exert an opposite trend. A significant increase in aroma release was found when phenolic compounds were added to the system, probably due to the contrasting effects of binding of volatile compounds caused by WP, for the polyphenol-protein interaction phenomenon. Our study could be applied to the formulation of new functional foods to enhance flavor release and modulate the presence and concentrations of phenolics and whey proteins in food emulsions/dispersions.

  2. 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)

  3. Solvent-free fabrication of polyHIPE microspheres for controlled release of growth factors.

    Science.gov (United States)

    Moglia, Robert; Whitely, Michael; Brooks, Megan; Robinson, Jennifer; Pishko, Michael; Cosgriff-Hernandez, Elizabeth

    2014-07-01

    The growth factor bone morphogenetic protein 2 (BMP-2) is utilized in surgical procedures to improve bone regeneration; however, current treatments deliver BMP-2 at amounts greater than 100,000 fold of physiological levels, which increases treatment costs and risk of side effects. Drug-eluting microcarriers developed to improve these therapies have faced significant commercialization challenges including particle size distributions, solvent removal, low encapsulation efficiency, and bioactivity loss. In this study, a solvent-free method is presented for fabrication of uniform polyHIPE microspheres for controlled growth factor release. Emulsion templating principles and fluid dynamics were used to fabricate uniform particles with tunable particle size (200-800 μm) and pore size (10-30 μm). The ability to independently tune particle and pore size is expected to provide excellent control of release kinetics. Overall, this solvent-free method for making porous microspheres displays strong promise for the controlled release of BMP-2 and other growth factors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Investigations of Takeout proteins' ligand binding and release mechanism using molecular dynamics simulation.

    Science.gov (United States)

    Zhang, Huijing; Yu, Hui; Zhao, Xi; Liu, Xiaoguang; Feng, Xianli; Huang, Xuri

    2016-07-29

    Takeout (To) proteins exist in a diverse range of insect species. They are involved in many important processes of insect physiology and behaviors. As the ligand carriers, To proteins can transport the small molecule to the target tissues. However, ligand release mechanism of To proteins is unclear so far. In this contribution, the process and pathway of the ligand binding and release are revealed by conventional molecular dynamics simulation, steered molecular dynamics simulation and umbrella sampling methods. Our results show that the α4-side of the protein is the unique gate for the ligand binding and release. The structural analysis confirms that the internal cavity of the protein has high rigidity, which is in accordance with the recent experimental results. By using the potential of mean force calculations in combination with residue cross correlation calculation, we concluded that the binding between the ligand and To proteins is a process of conformational selection. Furthermore, the conformational changes of To proteins and the hydrophobic interactions both are the key factors for ligand binding and release.

  5. Proteomics strategy for identifying candidate bioactive proteins in complex mixtures: application to the platelet releasate.

    LENUS (Irish Health Repository)

    O'Connor, Roisin

    2010-01-01

    Proteomic approaches have proven powerful at identifying large numbers of proteins, but there are fewer reports of functional characterization of proteins in biological tissues. Here, we describe an experimental approach that fractionates proteins released from human platelets, linking bioassay activity to identity. We used consecutive orthogonal separation platforms to ensure sensitive detection: (a) ion-exchange of intact proteins, (b) SDS-PAGE separation of ion-exchange fractions and (c) HPLC separation of tryptic digests coupled to electrospray tandem mass spectrometry. Migration of THP-1 monocytes in response to complete or fractionated platelet releasate was assessed and located to just one of the forty-nine ion-exchange fractions. Over 300 proteins were identified in the releasate, with a wide range of annotated biophysical and biochemical properties, in particular platelet activation, adhesion, and wound healing. The presence of PEDF and involucrin, two proteins not previously reported in platelet releasate, was confirmed by western blotting. Proteins identified within the fraction with monocyte promigratory activity and not in other inactive fractions included vimentin, PEDF, and TIMP-1. We conclude that this analytical platform is effective for the characterization of complex bioactive samples.

  6. Amnesia produced by altered release of neurotransmitters after intraamygdala injections of a protein synthesis inhibitor

    OpenAIRE

    Canal, Clinton E.; Chang, Qing; Paul E Gold

    2007-01-01

    Amnesia produced by protein synthesis inhibitors such as anisomycin provides major support for the prevalent view that the formation of long-lasting memories requires de novo protein synthesis. However, inhibition of protein synthesis might disrupt other neural functions to interfere with memory formation. Intraamygdala injections of anisomycin before inhibitory avoidance training impaired memory in rats tested 48 h later. Release of norepinephrine (NE), dopamine (DA), and serotonin, measured...

  7. Preparation of protein-loaded PLGA-PVP blend nanoparticles by nanoprecipitation method: entrapment, Initial burst and drug release kinetic studies

    Directory of Open Access Journals (Sweden)

    Shahryar Shakeri

    2015-07-01

    Full Text Available Objective(s:Despite of wide range applications of polymeric nanoparticles in protein delivery, there are some problems for the field of protein entrapment, initial burst and controlled release profile.   Materials and Methods: In this study, we investigated the influence of some changes in PLGA nanoparticles formulation to improve the initial and controlled release profile. Selected parameters were: pluronic F127, polysorbate 80 as surfactant, pH of inner aqueous phase, L/G ratio of PLGA polymer, volume of inner aqueous phase and addition of polyvinylpyrrolidone as an excipient. FITC-HSA was used as a model hydrophilic drug. The nanoparticles were prepared by nanoprecipitation.   Results:  Initial release of FITC-HSA from PLGA-tween 80 nanoparticles (opt-4, 61% was faster than control (PLGA-pluronic after 2.30 h of incubation. Results showed that decrease in pH of inner aqueous phase to pI of protein can decrease IBR but the release profile of protein is the same as control. Release profile with three phases including a initial burst b plateau and c final release phase was observed when we changed volume of inner aqueous phase and L/G ratio in formulation. Co-entrapment of HSA with PVP and pluronic reduced the IBR and controlled release profile in opt-19. Encapsulation efficiency was more than 97% and nanoparticles size and zeta potentials were mono-modal and -18.99 mV, respectively.   Conclusion:  In this research, we optimized a process for preparation of PLGA-PVP-pluronic nanoparticles of diameter less than 300 nm using nanoprecipitation method. This formulation showed a decreased initial burst and long lasting controlled release profile for FITC-HSA as a model drug for proteins.

  8. Temporal control of drug release from biodegradable polymer: multicomponent diclofenac sodium releasing PLGA 80/20 rod.

    Science.gov (United States)

    Nikkola, Lila; Viitanen, Petrus; Ashammakhi, Nureddin

    2009-05-01

    In our previous studies we have reported on the development of diclofenac sodium (DS) releasing rods. However, their drug release profiles were unsatisfactory. To enhance the drug release properties of the implant, we have developed a system whereby various elements can be combined into one implant. Melt extruded, self-reinforced (SR), and sterilized (S) DS-containing SR-PLGA 80/20 billets were combined to produce multicomponent implants with various compositions. These components were basically heat pressed together to form multicomponent rods. Drug release from single component and multicomponent rods was defined using a UV-Vis spectrophotometer. DS was released from individual components within 82-111 days and from multicomponent rods within 50-70 days. Thermal properties were analyzed using differential scanning calorimetry (DSC). The melting temperature (T(m)) of multicomponent implants was about 157 degrees C, change in heat fusion (DeltaH) was 13.3 J/g, and the glass transition temperature (T(g)) was 55.4 degrees C. Mechanical strength was measured for 2 weeks and it decreased from 55 to 15 MPa. In conclusion, by compression molding three components with different release rates it is possible to control the temporal release from multicomponent rods. Released DS concentrations were within range for 49-74 days depending on the fractions of individual components used.

  9. Corticotropin releasing factor (CRF) binding protein: a novel regulator of CRF and related peptides.

    Science.gov (United States)

    Behan, D P; De Souza, E B; Lowry, P J; Potter, E; Sawchenko, P; Vale, W W

    1995-10-01

    A 37-kDa corticotropin releasing factor (CRF) binding protein (CRF-BP) was purified from human plasma by repeated affinity purification and subsequently sequenced and cloned. The human and rat CRF-BP cDNAs encode proteins of 322 amino acids with one putative signal sequence, one N-glycosylation site, and 10 conserved cysteines. Human CRF-BP binds human CRF with high affinity but has low affinity for the ovine peptide. In contrast, sheep CRF-BP binds human and ovine CRF with high affinity. The CRF-BP gene consists of seven exons and six introns and is located on chromosome 13 and loci 5q of the mouse and human genomes, respectively. CRF-BP inhibits the adrenocorticotrophic hormone (ACTH) releasing properties of CRF in vitro. CRF-BP dimerizes after binding CRF and clears the peptide from blood. This clearance mechanism protects the maternal pituitary gland from elevated plasma CRF levels found during the third trimester of human pregnancy. CRF-BP is expressed in the brains of all species so far tested but is uniquely expressed in human liver and placenta. In brain, CRF-BP is membrane associated and is predominantly expressed in the cerebral cortex and subcortical limbic structures. In some brain areas CRF-BP colocalizes with CRF and CRF receptors. The protein is also present in pituitary corticotropes, where it is under positive glucocorticoid control, and is likely to locally modulate CRF-induced ACTH secretion. The ligand requirements of the CRF receptor and the CRF-BP can be distinguished in that central human CRF fragments, such as CRF (6-33) and CRF (9-33), have high affinity for CRF-BP but low affinity for the CRF receptor. The binding protein's ability to inhibit CRF-induced ACTH secretion can be reversed by CRF (6-33) and CRF (9-33), suggesting that ligand inhibitors may have utility in elevating free CRF levels in disease states associated with decreased CRF. Thus, by controlling the amount of free CRF which activates CRF receptors, it is likely that the CRF

  10. Reaction-Multi Diffusion Model for Nutrient Release and Autocatalytic Degradation of PLA-Coated Controlled-Release Fertilizer

    Directory of Open Access Journals (Sweden)

    Sayed Ameenuddin Irfan

    2017-03-01

    Full Text Available A mathematical model for the reaction-diffusion equation is developed to describe the nutrient release profiles and degradation of poly(lactic acid (PLA-coated controlled-release fertilizer. A multi-diffusion model that consists of coupled partial differential equations is used to study the diffusion and chemical reaction (autocatalytic degradation simultaneously. The model is solved using an analytical-numerical method. Firstly, the model equation is transformed using the Laplace transformation as the Laplace transform cannot be inverted analytically. Numerical inversion of the Laplace transform is used by employing the Zakian method. The solution is useful in predicting the nutrient release profiles at various diffusivity, concentration of extraction medium, and reaction rates. It also helps in explaining the transformation of autocatalytic concentration in the coating material for various reaction rates, times of reaction, and reaction-multi diffusion. The solution is also applicable to the other biodegradable polymer-coated controlled-release fertilizers.

  11. Protein quality control in the nucleus

    DEFF Research Database (Denmark)

    Nielsen, Sofie V.; Poulsen, Esben Guldahl; Rebula, Caio A.

    2014-01-01

    to aggregate, cells have evolved several elaborate quality control systems to deal with these potentially toxic proteins. First, various molecular chaperones will seize the misfolded protein and either attempt to refold the protein or target it for degradation via the ubiquitin-proteasome system...... to be particularly active in protein quality control. Thus, specific ubiquitin-protein ligases located in the nucleus, target not only misfolded nuclear proteins, but also various misfolded cytosolic proteins which are transported to the nucleus prior to their degradation. In comparison, much less is known about...... these mechanisms in mammalian cells. Here we highlight recent advances in our understanding of nuclear protein quality control, in particular regarding substrate recognition and proteasomal degradation....

  12. Inhibition of host protein synthesis by Sindbis virus: correlation with viral RNA replication and release of nuclear proteins to the cytoplasm.

    Science.gov (United States)

    Sanz, Miguel A; García-Moreno, Manuel; Carrasco, Luis

    2015-04-01

    Infection of mammalian cells by Sindbis virus (SINV) profoundly blocks cellular mRNA translation. Experimental evidence points to viral non-structural proteins (nsPs), in particular nsP2, as the mediator of this inhibition. However, individual expression of nsP1, nsP2, nsP3 or nsP1-4 does not block cellular protein synthesis in BHK cells. Trans-complementation of a defective SINV replicon lacking most of the coding region for nsPs by the co-expression of nsP1-4 propitiates viral RNA replication at low levels, and inhibition of cellular translation is not observed. Exit of nuclear proteins including T-cell intracellular antigen and polypyrimidine tract-binding protein is clearly detected in SINV-infected cells, but not upon the expression of nsPs, even when the defective replicon was complemented. Analysis of a SINV variant with a point mutation in nsP2, exhibiting defects in the shut-off of host protein synthesis, indicates that both viral RNA replication and the release of nuclear proteins to the cytoplasm are greatly inhibited. Furthermore, nucleoside analogues that inhibit cellular and viral RNA synthesis impede the blockade of host mRNA translation, in addition to the release of nuclear proteins. Prevention of the shut-off of host mRNA translation by nucleoside analogues is not due to the inhibition of eIF2α phosphorylation, as this prevention is also observed in PKR(-/-) mouse embryonic fibroblasts that do not phosphorylate eIF2α after SINV infection. Collectively, our observations are consistent with the concept that for the inhibition of cellular protein synthesis to occur, viral RNA replication must take place at control levels, leading to the release of nuclear proteins to the cytoplasm.

  13. Controlled release of insulin through hydrogels of (acrylic acid)/trimethylolpropane triacrylate

    Science.gov (United States)

    Raymundi, Vanessa C.; Aguiar, Leandro G.; Souza, Esmar F.; Sato, Ana C.; Giudici, Reinaldo

    2016-10-01

    Hydrogels of poly(acrylic acid) crosslinked with trimethylolpropane triacrylate (TMPTA) were produced through solution polymerization. After these hydrogels were loaded with insulin solution, they evidenced swelling. Experiments of controlled release of insulin through the hydrogels were performed in acidic and basic media in order to evaluate the rates of release of this protein provided by the referred copolymer. Additionally, a mathematical description of the system based on differential mass balance was made and simulated in MATLAB. The model consists of a system of differential equations which was solved numerically. As expected, the values of swelling index at the equilibrium and the rates of insulin release were inversely proportional to the degree of crosslinking. The mathematical model provided reliable predictions of release profiles with fitted values of diffusivity of insulin through the hydrogels in the range of 6.0 × 10-7-1.3 × 10-6 cm2/s. The fitted and experimental values of partition coefficients of insulin between the hydrogel and the medium were lower for basic media, pointing out good affinity of insulin for these media in comparison to the acidic solutions.

  14. Effects of Several Natural Macromolecules on the Stability and Controlled Release Properties of Water-in-Oil-in-Water Emulsions.

    Science.gov (United States)

    Li, Jinlong; Shi, Yiheng; Zhu, Yunping; Teng, Chao; Li, Xiuting

    2016-05-18

    Water-in-oil-in-water (W/O/W) emulsions are effective vehicles for embedding application of active compounds but limited by their thermodynamic instability and rapid release properties. The present study added bovine serum albumin, whey protein isolate, whey protein hydrolysate, sodium caseinate, carboxymethylcellulose sodium, fish gelatin, apple pectin, gum arabic, ι-carrageenan, and hydroxypropyl chitosan separately to the internal or external aqueous phase to investigate their effects on the physical stabilities and controlled release properties of W/O/W emulsions. The effects of the natural macromolecules in the internal and external aqueous phases were different and depended upon the macromolecule structure and its mass fraction. The addition of the natural macromolecule strengthened the interfaces of emulsions, which improved the physical stability. The natural macromolecules that improved the stability often did not improve controlled release. Therefore, the balance between these properties needs to be considered when adding natural macromolecules to a W/O/W emulsion.

  15. Evaluation of Calendula mucilage as a mucoadhesive and controlled release component in buccal tablets.

    Science.gov (United States)

    Sabale, V; Patel, V; Paranjape, A

    2014-01-01

    Mucoadhesive drug delivery systems were developed to sustain drug delivery via various mucus membranes for either local or systemic delivery of poorly absorbed drugs such as peptides and proteins as well as drugs that are subjected to high first-pass metabolism. The present study was undertaken to use isolated Calendula mucilage as a mucoadhesive agent and to formulate controlled release buccoadhesive tablets with an intention to avoid hepatic first-pass metabolism as well as to enhance residence time of drug in the buccal cavity. The mucilage was isolated from the Calendula petals by aqueous extraction method and characterized for various physiochemical parameters as well as for its adhesive properties. By using direct compression technique, tablets were prepared containing dried mucilage and chlorpheniramine maleate (CPM) as a model drug. Three batches of tablets were prepared and evaluated containing three mucoadhesive components namely Methocel K4M, Carbopol 974P and isolated Calendula mucilage in 16.66%, 33.33 % and 50 % (1:2:3 ratio) resulting in 9 different formulations. FTIR studies between mucilage and CPM suggested the absence of a chemical interaction between CPM and Calendula mucilage. The results of the study showed that the isolated mucilage had good physicochemical and morphological characteristics and tablets conformed to the pharmacopoeial specifications. Also in vitro release studies showed controlled action of drug with increasing the concentration of the isolated Calendula mucilage as a mucoadhesive agent in the formulations. Permeability studies indicated that permeability behavior was not statistically different (P>0.05) by changing the mucoadhesive component. The formulated mucoadhesive tablets for buccal administration containing 75 mg Calendula mucilage showed controlled drug release. Thus, mucoadhesive natural Calendula mucilage based buccal tablets for controlled release were successfully formulated.

  16. Reduced cognitive and psychomotor impairment with extended-release oxymorphone versus controlled-release oxycodone.

    Science.gov (United States)

    Schoedel, Kerri A; McMorn, Stephen; Chakraborty, Bijan; Zerbe, Kathleen; Sellers, Edward M

    2010-01-01

    Opioids provide effective pain control, yet have risks including adverse events (AEs) (e.g., constipation, nausea/vomiting, sedation) and cognitive/psychomotor effects. To compare cognitive and psychomotor effects of oxymorphone extended release (OM-ER) versus oxycodone controlled release (OC-CR). Randomized, double-blind, 5-way crossover Single inpatient research unit Nondependent recreational opioid users were administered single intact oral tablets of placebo, OM-ER (15 and 30 mg), and OC-CR (30 and 60 mg), separated by a 7- to 21-day washout. The divided attention (DA) test measured psychomotor impairment (e.g., manual tracking [e.g., percentage over road], target accuracy [e.g., target hits], reaction time [hit latency]). Visual analog scales measured alertness/drowsiness, agitation/relaxation, and dizziness. Sedative, stimulant, and dysphoric effects were measured using the Addiction Research Center Inventory Pentobarbital-Chlorpromazine-Alcohol (PCAG), Benzedrine Group (BG), and Lysergic Acid Diethylamide (LSD) scales, respectively. Comparisons were made between equianalgesic doses (OM-ER 15 mg vs OC-CR 30 mg; OM-ER 30 mg vs OC-CR 60 mg), within active drug doses, and between active drugs and placebo using least squares (LS) mean difference of the peak maximum (Emax) or minimum (Emin) effect using linear mixed model analysis of covariance. Thirty-five participants received all 5 treatments. Peak cognitive and psychomotor impairment (LS mean [SE]) was less with OM-ER than equianalgesic doses of OC-CR for reaction time (Emax hit latency, longer if impaired; 571.2 [13.4] vs 588.1 ms [13.4], P=0.03 for OM-ER 15 mg vs OC-CR 30 mg, respectively; 572.4 [13.4] vs 604.3 ms [13.4], P=0.03 for OM-ER 15 mg vs OC-CR 30 mg, respectively; 572.4 [13.4] vs 604.3 ms [13.4], PLSD, P<0.001 for both equianalgesic dose groups), and sedation (Emax, PCAG; P<0.001 for both equianalgesic dose groups) and less stimulation (BG, Emin; P=0.01 for OM-ER 15 mg vs OC-CR mg; P<0.001 for OM

  17. Release of periplasmic proteins of Brucella suis upon acidic shock involves the outer membrane protein Omp25.

    Science.gov (United States)

    Boigegrain, Rose-Anne; Salhi, Imed; Alvarez-Martinez, Maria-Teresa; Machold, Jan; Fedon, Yann; Arpagaus, Martine; Weise, Christoph; Rittig, Michael; Rouot, Bruno

    2004-10-01

    The survival and replication of Brucella in macrophages is initially triggered by a low intraphagosomal pH. In order to identify proteins released by Brucella during this early acidification step, we analyzed Brucella suis conditioned medium at various pH levels. No significant proteins were released at pH 4.0 in minimal medium or citrate buffer, whereas in acetate buffer, B. suis released a substantial amount of soluble proteins. Comparison of 13 N-terminal amino acid sequences determined by Edman degradation with their corresponding genomic sequences revealed that all of these proteins possessed a signal peptide indicative of their periplasmic location. Ten proteins are putative substrate binding proteins, including a homologue of the nopaline binding protein of Agrobacterium tumefaciens. The absence of this homologue in Brucella melitensis was due to the deletion of a 7.7-kb DNA fragment in its genome. We also characterized for the first time a hypothetical 9.8-kDa basic protein composed of five amino acid repeats. In B. suis, this protein contained 9 repeats, while 12 were present in the B. melitensis orthologue. B. suis in acetate buffer depended on neither the virB type IV secretory system nor the omp31 gene product. However, the integrity of the omp25 gene was required for release at acidic pH, while the absence of omp25b or omp25c displayed smaller effects. Together, these results suggest that Omp25 is involved in the membrane permeability of Brucella in acidic medium.

  18. Solid lipid nanoparticles (SLN) for controlled drug delivery--drug release and release mechanism.

    Science.gov (United States)

    zur Mühlen, A; Schwarz, C; Mehnert, W

    1998-03-01

    Solid lipid nanoparticles (SLN) are particulate systems for parenteral drug administration with mean particle diameters ranging from 50 up to 1000 nm. The model drugs tetracaine, etomidate and prednisolone were incorporated (1, 5 and 10%) to study the drug load, effect of drug incorporation on the structure of the lipid matrix and the release profiles and mechanism. SLN were produced by high pressure homogenization of aqueous surfactant solutions containing the drug-loaded lipids in the melted or in the solid state (500/1500 bar, 3/10 cycles). In case of tetracaine and etomidate, high drug loadings up to 10% could be achieved when using Compritol 888 ATO and Dynasan 112 as matrix material. The melting behavior of the drug loaded particles revealed that little or no interactions between drug and lipid occurred. A burst drug release (100% release < 1 min) was observed with tetracaine and etomidate SLN, which was attributed to the large surface area of the nanoparticles and drug enrichment in the outer shell of the particles. In contrast, prednisolone loaded SLN showed a distinctly prolonged release over a monitored period of 5 weeks. Depending on the chemical nature of the lipid matrix, 83.8 and 37.1% drug were released (cholesterol and compritol, respectively). These results demonstrate the principle suitability of SLN as a prolonged release formulation for lipophilic drugs.

  19. Release mechanisms behind polysaccharides-based famotidine controlled release matrix tablets.

    Science.gov (United States)

    Elmowafy, Enas M; Awad, Gehanne A S; Mansour, Samar; El-Shamy, Abd El-Hamid A

    2008-01-01

    Polysaccharides, which have been explored to possess gelling properties and a wide margin of safety, were used to formulate single-unit floating matrix tablets by a direct compression technique. This work has the aim to allow continuous slow release of famotidine above its site of absorption. The floating approach was achieved by the use of the low density polypropylene foam powder. Polysaccharides (kappa-carrageenan, gellan gum, xyloglucan, and pectin) and blends of polysaccharides (kappa-carrageenan and gellan gum) and cellulose ethers (hydroxypropylmethyl cellulose, hydroxypropylcellulose, sodium carboxymethyl cellulose) were tried to modulate the release characteristics. The prepared floating tablets were evaluated for their floating behavior, matrix integrity, swelling studies, in vitro drug release studies, and kinetic analysis of the release data. The differential scanning calorimetry and Fourier transform infrared spectroscopy studies revealed that changing the polymer matrix system by formulation of polymers blends resulted in formation of molecular interactions which may have implications on drug release characteristics. This was obvious from the retardation in drug release and change in its mechanistics.

  20. Controlled Release of the Indomethacin Microencapsulation Based on Layer-by-layer Assembly by Polyelectrolyte Multilayers

    Institute of Scientific and Technical Information of China (English)

    CHEN You-fang; LIN Xian-fu

    2007-01-01

    Indomethacin has been encapsulated with polyelectrolyte multilayers for controlled release. Gelatin and alginate were alternatively deposited on indomethacin microcrystals. The released amount of indomethacin from coated microcrystals in pH6. 8phosphate buffer solution (PBS) was measured with a UV spectrophometer. The polyelectrolyte multilayer capsule thickness was proved to control the release rate. The effects of osmotic pressure existed during the release process of indomethacin from microcapsules coated by (gelatin/alginate) 4.

  1. Lateral release of proteins from the TOM complex into the outer membrane of mitochondria.

    Science.gov (United States)

    Harner, Max; Neupert, Walter; Deponte, Marcel

    2011-07-15

    The TOM complex of the outer membrane of mitochondria is the entry gate for the vast majority of precursor proteins that are imported into the mitochondria. It is made up by receptors and a protein conducting channel. Although precursor proteins of all subcompartments of mitochondria use the TOM complex, it is not known whether its channel can only mediate passage across the outer membrane or also lateral release into the outer membrane. To study this, we have generated fusion proteins of GFP and Tim23 which are inserted into the inner membrane and, at the same time, are spanning either the TOM complex or are integrated into the outer membrane. Our results demonstrate that the TOM complex, depending on sequence determinants in the precursors, can act both as a protein conducting pore and as an insertase mediating lateral release into the outer membrane.

  2. Protein A is released into the Staphylococcus aureus culture supernatant with an unprocessed sorting signal.

    Science.gov (United States)

    O'Halloran, Dara P; Wynne, Kieran; Geoghegan, Joan A

    2015-04-01

    The immunoglobulin binding protein A (SpA) of Staphylococcus aureus is synthesized as a precursor with a C-terminal sorting signal. The sortase A enzyme mediates covalent attachment to peptidoglycan so that SpA is displayed on the surface of the bacterium. Protein A is also found in the extracellular medium, but the processes involved in its release are not fully understood. Here, we show that a portion of SpA is released into the supernatant with an intact sorting signal, indicating that it has not been processed by sortase A. Release of SpA was reduced when the native sorting signal of SpA was replaced with the corresponding region of another sortase-anchored protein (SdrE). Similarly, a reporter protein fused to the sorting signal of SpA was released to a greater extent than the same polypeptide fused to the SdrE sorting signal. Released SpA protected bacteria from killing in human blood, indicating that it contributes to immune evasion.

  3. Quantitative analysis of Nipah virus proteins released as virus-like particles reveals central role for the matrix protein

    Directory of Open Access Journals (Sweden)

    Eaton Bryan T

    2007-01-01

    Full Text Available Abstract Background Nipah virus (NiV is an emerging paramyxovirus distinguished by its ability to cause fatal disease in both animal and human hosts. Together with Hendra virus (HeV, they comprise the genus Henipavirus in the Paramyxoviridae family. NiV and HeV are also restricted to Biosafety Level-4 containment and this has hampered progress towards examining details of their replication and morphogenesis. Here, we have established recombinant expression systems to study NiV particle assembly and budding through the formation of virus-like particles (VLPs. Results When expressed by recombinant Modified Vaccinia virus Ankara (rMVA or plasmid transfection, individual NiV matrix (M, fusion (F and attachment (G proteins were all released into culture supernatants in a membrane-associated state as determined by sucrose density gradient flotation and immunoprecipitation. However, co-expression of F and G along with M revealed a shift in their distribution across the gradient, indicating association with M in VLPs. Protein release was also altered depending on the context of viral proteins being expressed, with F, G and nucleocapsid (N protein reducing M release, and N release dependent on the co-expression of M. Immunoelectron microscopy and density analysis revealed VLPs that were similar to authentic virus. Differences in the budding dynamics of NiV proteins were also noted between rMVA and plasmid based strategies, suggesting that over-expression by poxvirus may not be appropriate for studying the details of recombinant virus particle assembly and release. Conclusion Taken together, the results indicate that NiV M, F, and G each possess some ability to bud from expressing cells, and that co-expression of these viral proteins results in a more organized budding process with M playing a central role. These findings will aid our understanding of paramyxovirus particle assembly in general and could help facilitate the development of a novel vaccine

  4. Controlling the loading of protein nanocages

    NARCIS (Netherlands)

    Rurup, W.F.

    2013-01-01

    The work described in this thesis focuses on the use of natural protein building blocks to assemble nanocages. Most common strategies for the loading of different protein nanocages suffer from a lack of numerical control over cargo loading. The aim of this thesis was to create a controllable method

  5. Novel anhydrous emulsions: formulation as controlled release vehicles.

    Science.gov (United States)

    Suitthimeathegorn, Orawan; Jaitely, Vikas; Florence, Alexander T

    2005-07-25

    Novel anhydrous emulsions, which may offer some advantages as depot or reservoir vehicles for lipophilic drugs in controlled delivery systems, were formulated using castor oil as the disperse phase and dimethicone or cyclopentasiloxane as the continuous phase. Among the emulsifiers studied only silicone surfactants (cyclomethicone/dimethicone copolyols) which were miscible in silicone oil stabilized the emulsions. Cyclomethicone/PEG/PPG-18/18 Dimethicone and Cyclopentasiloxane/PEG/PPG-18/18 Dimethicone were more effective in lowering the interfacial tension between castor oil and both dimethicone and cyclopentasiloxane. Emulsions formulated using either of these two surfactants were found to be stable against phase separation and exhibited least globule growth over 168 h. The average particle size was found to be 2-6 microm in these systems formed by probe sonication. Slow release patterns of 3H-dehydroepiandrosterone (DHEA) and 3H-dexamethasone solubilized in the disperse castor oil phase into an aqueous dialyzing medium were observed over 48 h.

  6. PH-triggered micellar membrane for controlled release microchips

    KAUST Repository

    Yang, Xiaoqiang

    2011-01-01

    A pH-responsive membrane based on polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer was developed on a model glass microchip as a promising controlled polymer delivery system. The PS-b-P4VP copolymer assembles into spherical and/or worm-like micelles with styrene block cores and pyridine coronas in selective solvents. The self-assembled worm-like morphology exhibited pH-responsive behaviour due to the protonation of the P4VP block at low pH and it\\'s deprotonation at high pH and thus constituting a switchable "off/on" system. Doxorubicin (Dox) was used as cargo to test the PS-b-P4VP membrane. Luminescence experiments indicated that the membrane was able to store Dox molecules within its micellar structure at neutral pH and then release them as soon as the pH was raised to 8.0. The performance of the cast membrane was predictable and most importantly reproducible. The physiochemical and biological properties were also investigated carefully in terms of morphology, cell viability and cell uptake. This journal is © The Royal Society of Chemistry.

  7. Quantification of malaria parasite release from infected erythrocytes: inhibition by protein-free media

    Directory of Open Access Journals (Sweden)

    Zimmerberg Joshua

    2007-05-01

    Full Text Available Abstract Background Intracellular malaria parasites leave their host erythrocytes to infect neighbouring cells after each cycle of asexual replication. No method is currently available for the direct quantification of parasite release. Method and results To quantify parasite release process, human erythrocytes infected with Plasmodium falciparum were injected into sealed chambers at optimal density, where they progressed through the end of the erythrocyte cycle. Each event of parasite release inside the chamber at the site of erythrocyte rupture leaves on the chamber wall a footprint, composed of 1 separated parasites, 2 a digestive vacuole with haemozoin, and 3 fragments of the ruptured membranes. These footprints are stable for hours, allowing precise identification using differential interference contrast (DIC microscopy. The relative rate of parasite release is defined as the percent of such footprints out of all schizonts injected and incubated into chamber at 37°C for two hours. The method is highly reproducible, easy to perform, and does not require expensive equipment. Additionally, this method allows one to analyse cell and release site morphology, which adds information about the release process and the quality of the culture. The method is used here to show that swelling of schizonts caused by protein-free media inhibits parasite release. Conclusion In this study, a novel method is described to count sites of parasite release by microscopy. Besides the direct estimation of parasite release from infected erythrocytes, this method provides a morphological evaluation of normal infected cells approaching the end of the plasmodial life cycle, or pathological forms accumulated as the result of experimental intervention in the parasite release process. One may now accurately estimate the relative parasite release rate at the time of cycle transition, without any obligatory coupling to parasite invasion.

  8. RRE-dependent HIV-1 Env RNA effects on Gag protein expression, assembly and release

    Energy Technology Data Exchange (ETDEWEB)

    López, Claudia S., E-mail: lopezcl@ohsu.edu [Departments of Molecular Microbiology and Immunology, Oregon Health and Sciences University, 3181 SW Sam Jackson Park Road, Portland, OR 97239 (United States); Sloan, Rachel; Cylinder, Isabel [Departments of Molecular Microbiology and Immunology, Oregon Health and Sciences University, 3181 SW Sam Jackson Park Road, Portland, OR 97239 (United States); Kozak, Susan L.; Kabat, David [Biochemistry and Molecular Biology, Oregon Health and Sciences University, 3181 SW Sam Jackson Park Road, Portland, OR 97239 (United States); Barklis, Eric, E-mail: barklis@ohsu.edu [Departments of Molecular Microbiology and Immunology, Oregon Health and Sciences University, 3181 SW Sam Jackson Park Road, Portland, OR 97239 (United States)

    2014-08-15

    The HIV-1 Gag proteins are translated from the full-length HIV-1 viral RNA (vRNA), whereas the envelope (Env) protein is translated from incompletely spliced Env mRNAs. Nuclear export of vRNAs and Env mRNAs is mediated by the Rev accessory protein which binds to the rev-responsive element (RRE) present on these RNAs. Evidence has shown there is a direct or indirect interaction between the Gag protein, and the cytoplasmic tail (CT) of the Env protein. Our current work shows that env gene expression impacts HIV-1 Gag expression and function in two ways. At the protein level, full-length Env expression altered Gag protein expression, while Env CT-deletion proteins did not. At the RNA level, RRE-containing Env mRNA expression reduced Gag expression, processing, and virus particle release from cells. Our results support models in which Gag is influenced by the Env CT, and Env mRNAs compete with vRNAs for nuclear export. - Highlights: • At the protein level, full-length HIV-1 Env alters Gag protein expression. • HIV-1 Env RNA expression reduces Gag levels and virus release. • Env RNA effects on Gag are dependent on the RRE. • RRE-containing Env RNAs compete with vRNAs for nuclear export.

  9. A Preliminary Study on Natural Matrix Materials for Controlled Release Nitrogen Fertilizers

    Institute of Scientific and Technical Information of China (English)

    DU Chang-Wen; ZHOU Jian-Min; WANG Huo-Yan; LI Shou-Tian

    2004-01-01

    A controlled release N fertilizer was developed by the carrier method using natural polysaccharides (PS)and urea. The results showed that mixing of PS and urea led to significant control of urea release. When a cross-linker (boric acid or glutaraldehyde) was added, a better control effect was observed. During a 30 min leaching time the nitrogen release rate from the controlled release fertilizer was nearly constant, which was significantly different from normal urea. One of the controlled release mechanisms was related to space resistance from a large molecular structure. Infrared (IR) analysis indicated that interaction of PS with urea was through a hydrogen bond or a covalent bond. These bonds created an α-helix or high molecular network fertilizer carrier system, which was another reason for a controlled nutrient release. Pot experiment showed that nitrogen use efficiency could increase significantly with a carrier fertilizer.

  10. Poly (lactic-co-glycolic acid) controlled release systems: experimental and modeling insights

    Science.gov (United States)

    Hines, Daniel J.; Kaplan, David L.

    2013-01-01

    Poly-lactic-co-glycolic acid (PLGA) has been the most successful polymeric biomaterial for use in controlled drug delivery systems. There are several different chemical and physical properties of PLGA that impact the release behavior of drugs from PLGA delivery devices. These properties must be considered and optimized in drug release device formulation. Mathematical modeling is a useful tool for identifying, characterizing, and predicting the mechanisms of controlled release. The advantages and limitations of poly (lactic-co-glycolic acid) for controlled release are reviewed, followed by a review of current approaches in controlled release technology that utilize PLGA. Mathematical modeling applied towards controlled release rates from PLGA-based devices will also be discussed to provide a complete picture of state of the art understanding of the control achievable with this polymeric system, as well as the limitations. PMID:23614648

  11. Poly(lactic-co-glycolic) acid-controlled-release systems: experimental and modeling insights.

    Science.gov (United States)

    Hines, Daniel J; Kaplan, David L

    2013-01-01

    Poly(lactic-co-glycolic acid) (PLGA) has been the most successful polymeric biomaterial used in controlled drug delivery systems. There are several different chemical and physical properties of PLGA that impact the release behavior of drugs from PLGA delivery devices. These properties must be considered and optimized in the formulation of drug release devices. Mathematical modeling is a useful tool for identifying, characterizing, and predicting mechanisms of controlled release. The advantages and limitations of poly(lactic-co-glycolic acid) for controlled release are reviewed, followed by a review of current approaches in controlled-release technology that utilize PLGA. Mathematical modeling applied toward controlled-release rates from PLGA-based devices also will be discussed to provide a complete picture of a state-of-the-art understanding of the control that can be achieved with this polymeric system, as well as the limitations.

  12. Controlled-release NPK fertilizer encapsulated by polymeric membranes.

    Science.gov (United States)

    Jarosiewicz, Anna; Tomaszewska, Maria

    2003-01-15

    The commercial granular fertilizer NPK6-20-30 was coated using polysulfone (PSF), polyacrylonitrile (PAN), and cellulose acetate (CA). The coatings were formed from the polymer solutions by the phase inversion technique. Measurements of the thickness and porosity of the prepared coatings and a microphotographic observation of the coatings were performed. The physical properties of the coatings influence the release rate of macronutrients which are present in the core of the coated fertilizer. In the case of PAN coating with 60.45% porosity, prepared from a 16% polymer solution, 100% of NH(4)(+) and P(2)O(5) was released after 4 h of test and 99.7% of K(+) after 5 h of test, whereas in the case of coating with 48.8% porosity, 31.8% of NH(4)(+), 16.7% of P(2)O(5), and 11.6% of K(+) was released after 5 h. In all experiments, different selectivities of the coatings in terms of the release of components were observed. The release of potassium through the coatings made of PSF and PAN was the slowest. The same tendency was observed for the release of nitrogen through a coating of CA. The release of fertilizer active components was the slowest in the case of PSF. The lowest porosity coating was prepared from the 18% PSF solution.

  13. Preparation and characterization of metoprolol controlled-release solid dispersions.

    Science.gov (United States)

    Varshosaz, Jaleh; Faghihian, Hossein; Rastgoo, Kobra

    2006-01-01

    In recent years, great attention has been paid to using solid dispersions to make sustained-release drugs. The objective of this study is to produce sustained-release systems of metoprolol tartrate using solid dispersion techniques and to evaluate their physicochemical characteristics. The solid dispersions were produced by melting and solvent methods, containing 7%, 15%, or 25% of the drug and different ratios of Eudragit RLPO and RSPO in ratios of 0:10, 3:7, 5:5, 7:3, and 10:0. Drug release profiles were determined by USP XXIII rotating paddle method in phosphate buffer solution (pH 6.8). XRD, DSC, IR, and microscopic observations were performed to evaluate the physical characteristics of solid dispersions. Results showed that the drug release from dispersions was at a slower rate than pure drug and physical mixtures. Moreover, the formulations containing greater ratios of Eudragit RSPO showed slower release rates and smaller DE8% but larger mean dissolution time than those containing greater ratios of Eudragit RLPO. Dispersions with particle size of less than 100 microm containing 7% of metoprolol and Eudragit RL:RS 5:5 (solvent method) and those with the ratio of 3:7 (melting method) had similar release pattern to Lopressor sustained-release tablets by zero-order and Higuchi kinetics, respectively.

  14. Conductive polymers for controlled release and treatment of central nervous system injury

    Science.gov (United States)

    Saigal, Rajiv

    [(D,L-lactide-co-glycolide)-co-polyethylene glycol] (PLGA-PEG) nanoparticles and then demonstrated scalable incorporation and controlled release. In a functional application, electronically-controlled release of minocycline nanoparticles was used to rescue primary spinal cord neurons from an excitotoxic environment in vitro. This approach offers a wide range of therapeutic possibilities, especially for treating traumatic lesions of the central nervous system. Finally, we explored use of conductive polymers for directed differentiation of progenitor cells. Retinal progenitors were seeded on custom polypyrrole cell culture devices and subjected to a biomimetic pattern of electrical stimulation. Stimulated cells showed phenotypic changes, increased neurite outgrowth, increased immunocytochemical expression of cone rod homeobox (CRX) and protein kinase C (PK-C), and decreased expression of glial fibrillary acidic protein (GFAP). Biomimetic stimulation thus led cells towards early photoreceptor and bipolar cell fates, and away from an astrocytic cell fate. Electrical stimulation via a conductive polymer offers a novel approach for directing differentiation of progenitor cells.

  15. Effect of diluents on tablet integrity and controlled drug release.

    Science.gov (United States)

    Zhang, Y E; Schwartz, J B

    2000-07-01

    The objective of this study was to evaluate the effect of diluents and wax level on tablet integrity during heat treatment and dissolution for sustained-release formulations and the resultant effect on drug release. Dibasic calcium phosphate dihydrate (DCPD), microcrystalline cellulose (MCC), and lactose were evaluated for their effect on tablet integrity during drug dissolution and heat treatment in wax matrix formulations. A newly developed direct compression diluent, dibasic calcium phosphate anhydrous (DCPA), was also evaluated. Compritol 888 ATO was used as the wax matrix material, with phenylpropanolamine hydrochloride (PPA) as a model drug. Tablets were made by direct compression and then subjected to heat treatment at 80 degrees C for 30 min. The results showed that MCC, lactose, and DCPA could maintain tablets intact during heat treatment above the melting point of wax (70 degrees C-75 degrees C). However, DCPD tablets showed wax egress during the treatment. MCC tablets swelled and cracked during drug dissolution and resulted in quick release. DCPD and lactose tablets remained intact during dissolution and gave slower release than MCC tablets. DCPA tablets without heat treatment disintegrated very quickly and showed immediate release. In contrast, heat-treated DCPA tablets remained intact through the 24-hr dissolution test and only released about 80% PPA at 6 hr. In the investigation of wax level, DCPD was used as the diluent. The drug release rate decreased as the wax content increased from 15% to 81.25%. The dissolution data were best described by the Higuchi square-root-of-time model. Diluents showed various effects during heat treatment and drug dissolution. The integrity of the tablets was related to the drug release rate. Heat treatment retarded drug release if there was no wax egress.

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

    NARCIS (Netherlands)

    VANDERVEEN, J; EISSENS, AC; LERK, CF

    1994-01-01

    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 measur

  17. Use of natural and biobased materials for controlled-release of urea in water: Environmental applications

    Science.gov (United States)

    Urea pearls were encapsulated in cloisite-based matrices using different natural materials (lignin, beeswax and latex) to control the release of urea over time. It was found that all cloisite-based fertilizer tablets showed better release profiles than neat urea tablets. The best release profile was...

  18. 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.

  19. Identification of thioredoxin target disulfides in proteins released from barley aleurone layers

    DEFF Research Database (Denmark)

    Hägglund, Per; Bunkenborg, J.; Yang, Fen

    2010-01-01

    Thioredoxins are ubiquitous disulfide reductases involved in a wide range of cellular processes including DNA synthesis, oxidative stress response and apoptosis. In cereal seeds thioredoxins are proposed to facilitate the germination process by reducing disulfide bonds in storage proteins and other...... targets in the starchy endosperm. Here we have applied a thiol-specific labeling approach to identify specific disulfide targets of barley thioredoxin in proteins released from barley aleurone layers incubated in buffer containing gibberellic acid....

  20. Controlled-release of Avermectin from Organically Modified Hydrotalcite-like Compound Nanohybrids

    Institute of Scientific and Technical Information of China (English)

    QIU,Depeng; LI,Yonghai; FU,Xiying; JIANG,Zhen; ZHAO,Xinyan; WANG,Tian; HOU,Wanguo

    2009-01-01

    The intercalation of avermectin (AVM)into sodium dodecyl sulfate(SDS)modified hydrotalcite-like com-pounds(HTlc) was carried out using an evaporating solvent enhanced intercalation method to obtain AVM-SDS-HTlc nanohybrids. It was found that the nanohybrids could well control the release of avermectin, showing the nanohybrids are a potential pesticide controlled-release formulation.The release of avermectin from AVM-SDS-HTlc nanohybrids is dependent on the pH.temperature and the presence of electrolyte in release me-dium. Acidic medium and higher temperature and the presence of electrolytes may induce the higher release rate of avermectin. The release process of avermectin from AVM-SDS-HTlc nanohybrids can be described by pseudo-first-order release kinetics, and the activation energy of release is 279 kJ/mol.

  1. Remotely Triggered Scaffolds for Controlled Release of Pharmaceuticals

    Directory of Open Access Journals (Sweden)

    Clare Hoskins

    2013-04-01

    Full Text Available Fe3O4-Au hybrid nanoparticles (HNPs have shown increasing potential for biomedical applications such as image guided stimuli responsive drug delivery. Incorporation of the unique properties of HNPs into thermally responsive scaffolds holds great potential for future biomedical applications. Here we successfully fabricated smart scaffolds based on thermo-responsive poly(N-isopropylacrylamide (pNiPAM. Nanoparticles providing localized trigger of heating when irradiated with a short laser burst were found to give rise to remote control of bulk polymer shrinkage. Gold-coated iron oxide nanoparticles were synthesized using wet chemical precipitation methods followed by electrochemical coating. After subsequent functionalization of particles with allyl methyl sulfide, mercaptodecane, cysteamine and poly(ethylene glycol thiol to enhance stability, detailed biological safety was determined using live/dead staining and cell membrane integrity studies through lactate dehydrogenase (LDH quantification. The PEG coated HNPs did not show significant cytotoxic effect or adverse cellular response on exposure to 7F2 cells (p < 0.05 and were carried forward for scaffold incorporation. The pNiPAM-HNP composite scaffolds were investigated for their potential as thermally triggered systems using a Q-switched Nd:YAG laser. These studies show that incorporation of HNPs resulted in scaffold deformation after very short irradiation times (seconds due to internal structural heating. Our data highlights the potential of these hybrid-scaffold constructs for exploitation in drug delivery, using methylene blue as a model drug being released during remote structural change of the scaffold.

  2. Studies on pectins as potential hydrogel matrices for controlled-release drug delivery.

    Science.gov (United States)

    Sungthongjeen, S; Pitaksuteepong, T; Somsiri, A; Sriamornsak, P

    1999-12-01

    Polymeric hydrogels are widely used as controlled-release matrix tablets. In the present study, we investigated high-methoxy pectins for their potential value in controlled-release matrix formulations. The effects of compression force, ratio of drug to pectin, and type of pectin on drug release from matrix tablets were also investigated. The results of the in vitro release studies show that the drug release from compressed matrix tablets prepared from pectin can be modified by changing the amount and the type of pectin in the matrix tablets. However, compression force did not significantly affect the drug release. The mechanisms controlling release rate were discussed with respect to drug diffusion through the polymer matrices, but may be more complex.

  3. In vitro slow-release urea contained in rice straw-based diets to increase efficiency of rumen microbial protein synthesis

    OpenAIRE

    Dede Kardaya; K. G. Wiryawan; A. Parakkasi; H.M Winugroho

    2010-01-01

    Effect of slow-release urea on efficiency of rumen microbial protein synthesis (EMPS) was examined using an in vitro technique. The objective of this experiment was to reveal the in vitro slow-release urea characteristics of zinc-urea, zeolites-urea, and zeolites-zinc-urea in relation to EMPS observed in different incubation time. The experimental design employed was randomized block design with 4 x 3 factorial plus a control treatment, and conducted in two replications. Factors were various ...

  4. Protein overexport in a Saccharomyces cerevisiae mutant is not due to facilitated release of cell-surface proteins.

    Science.gov (United States)

    Alexieva, K I; Venkov, P V

    2000-01-01

    Saccharomyces cerevisiae strain MW11 is a temperature-sensitive mutant which exports twenty times more proteins at 37 degrees C than parental or wild-type strains do. To understand the mechanism underlying the protein overexport in the mutant the possibility of an altered cell-wall structure leading to facilitated release of cell-surface proteins was studied. Data on calcofluor white and zymolyase sensitivities, resistance to killer 1 toxin and determination of exported acid phosphatase and invertase did not provide evidence for alterations in the cell-wall structure that could explain the protein overexport phenotype. The results were obtained in experiments when transcription of mutated gene was discontinued which permits the full expression of the protein overexport phenotype.

  5. Interactions between Surfactants in Solution and Electrospun Protein Fibers: Effects on Release Behavior and Fiber Properties.

    Science.gov (United States)

    Stephansen, Karen; García-Díaz, María; Jessen, Flemming; Chronakis, Ioannis S; Nielsen, Hanne M

    2016-03-07

    Intermolecular interaction phenomena occurring between endogenous compounds, such as proteins and bile salts, and electrospun compounds are so far unreported, despite the exposure of fibers to such biorelevant compounds when applied for biomedical purposes, e.g., tissue engineering, wound healing, and drug delivery. In the present study, we present a systematic investigation of how surfactants and proteins, as physiologically relevant components, interact with insulin-loaded fish sarcoplasmic protein (FSP) electrospun fibers (FSP-Ins fibers) in solution and thereby affect fiber properties such as accessible surface hydrophilicity, physical stability, and release characteristics of an encapsulated drug. Interactions between insulin-loaded protein fibers and five anionic surfactants (sodium taurocholate, sodium taurodeoxycholate, sodium glycocholate, sodium glycodeoxycholate, and sodium dodecyl sulfate), a cationic surfactant (benzalkonium chloride), and a neutral surfactant (Triton X-100) were studied. The anionic surfactants increased the insulin release in a concentration-dependent manner, whereas the neutral surfactant had no significant effect on the release. Interestingly, only minute amounts of insulin were released from the fibers when benzalkonium chloride was present. The FSP-Ins fibers appeared dense after incubation with this cationic surfactant, whereas high fiber porosity was observed after incubation with anionic or neutral surfactants. Contact angle measurements and staining with the hydrophobic dye 8-anilino-1-naphthalenesulfonic acid indicated that the FSP-Ins fibers were hydrophobic, and showed that the fiber surface properties were affected differently by the surfactants. Bovine serum albumin also affected insulin release in vitro, indicating that also proteins may affect the fiber performance in an in vivo setting.

  6. A novel controlled-release system for antibacterial enzyme lysostaphin delivery using hydroxyapatite/chitosan composite bone cement.

    Directory of Open Access Journals (Sweden)

    Bai Xue

    Full Text Available In this work, a lysostaphin-loaded, control-released, self-setting and injectable porous bone cement with efficient protein delivery was prepared by a novel setting method using hydroxyapatite/chitosan (HA/CS composite scaffold. The cement samples were made through cementitious reactions by mixing solid powder, a mixture of HA/CS composite particles, lysostaphin, Ca(OH2, CaCO3 and NaHCO3, with setting liquid containing citric acid, acetic acid, NaH2PO4, CaCl2 and poloxamer. The setting parameters of the cement samples were determined. The results showed that the final setting time was 96.6±5.2 min and the pH value increased from approximately 6.2 to nearly 10 during the setting process and the porosity was 34% at the end. And the microstructure and composition were detected by scanning electron microscopy (SEM, x-ray diffraction and Fourier transform-infrared spectroscopy. For the release behavior of lysostaphin loaded in the cement sample, the in vitro cement extract experiment indicated that about 94.2±10.9% of the loaded protein was released before day 8 and the in vivo Qdot 625 fluorescence tracking experiment showed that the loaded protein released slower than the free one. Then the biocompatibility of the cement samples was evaluated using the methylthiazol tetrazolium assay, SEM and hematoxylin-eosin staining, which suggested good biocompatibility of cement samples with MC 3T3-E1 cells and subcutaneous tissues of mice. Finally the antibacterial activity assay indicated that the loaded lysostaphin had good release ability and strong antibacterial enzymatic activity against methicillin-resistant Staphylococcus aureus. Collectively, all the results suggested that the lysostaphin-loaded self-setting injectable porous bone cement released the protein in a controlled and effective way and the protein activity was well retained during the setting and releasing process. Thus this bone cement can be potentially applied as a combination of

  7. Desktop 3D printing of controlled release pharmaceutical bilayer tablets.

    Science.gov (United States)

    Khaled, Shaban A; Burley, Jonathan C; Alexander, Morgan R; Roberts, Clive J

    2014-01-30

    Three dimensional (3D) printing was used as a novel medicine formulation technique for production of viable tablets capable of satisfying regulatory tests and matching the release of standard commercial tablets. Hydroxypropyl methylcellulose (HPMC 2208) (Methocel™ K100M Premium) and poly(acrylic acid) (PAA) (Carbopol(®) 974P NF) were used as a hydrophilic matrix for a sustained release (SR) layer. Hypromellose(®) (HPMC 2910) was used as a binder while microcrystalline cellulose (MCC) (Pharmacel(®) 102) and sodium starch glycolate (SSG) (Primojel(®)) were used as disintegrants for an immediate release (IR) layer. Commercial guaifenesin bi-layer tablets (GBT) were used as a model drug (Mucinex(®)) for this study. There was a favourable comparison of release of the active guaifenesin from the printed hydrophilic matrix compared with the commercially available GBT. The printed formulations were also evaluated for physical and mechanical properties such as weight variation, friability, hardness and thickness as a comparison to the commercial tablet and were within acceptable range as defined by the international standards stated in the United States Pharmacopoeia (USP). All formulations (standard tablets and 3D printed tablets) showed Korsmeyer-Peppas n values between 0.27 and 0.44 which indicates Fickian diffusion drug release through a hydrated HPMC gel layer. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Factors controlling alkali salt deposition in recovery boilers. Release mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    McKeough, P.; Kurkela, M.; Kylloenen, H.; Tapola, E. [VTT Energy, Espoo (Finland). Process Technology Group

    1997-10-01

    The research was part of an ongoing cooperative research effort aimed at developing a model to describe the behaviour of inorganic compounds in kraft recovery boilers. During 1996 experimental investigations of sulphur release were continued. Experiments at elevated pressures and employing larger particle sizes were performed in order to gain information about mass transfer effects. The first experiments yielding data on the rates of the sulphur-release reactions were performed. This data will be used as the basis of a drop model for sulphur release being developed in cooperation with another research group. The other part of the work during 1996 explored the possibility of using chemical equilibrium calculations to predict the release of sodium, potassium and chlorine in the recovery furnace. The approach is essentially different from that employed in earlier studies in that the effects of fume formation are taken into account. So far, the predictions of the chemical equilibrium release model have, in no way, conflicted with field measurements. (orig.)

  9. Rheological behaviour and physical properties of controlled-release gluten-based bioplastics.

    Science.gov (United States)

    Gómez-Martínez, D; Partal, P; Martínez, I; Gallegos, C

    2009-03-01

    Bioplastics based on glycerol, water and wheat gluten have been manufactured in order to determine the effect that mechanical processing and further thermal treatments exert on different thermo-mechanical properties of the biomaterials obtained. An "active agent", KCl was incorporated in these matrices to develop controlled-release formulations. Oscillatory shear, dynamic mechanical thermal analysis (DMTA), diffusion and water absorption tests were carried out in order to study the influence of the above-mentioned treatments on the physico-chemical characteristics and rheological behaviour of these bioplastic samples. Wheat gluten protein-based bioplastics studied in this work present a high ability for thermosetting modification, due to protein denaturation, which may favour the development of a wide variety of biomaterials. Bioplastic hygroscopic properties depend on plasticizer nature and processing procedure, and may be a key factor for industrial applications where water absorption is required. On the other hand, high water absorption and slow KCl release from bioplastic samples (both of them suitable properties in agricultural applications) may be obtained by adding citric acid to a given formulation, at selected processing conditions.

  10. FORMULATION AND EVALUATION OF DICLOFENAC CONTROLLED RELEASE TABLETS EMPLOYING OLIBANUM RESIN

    Directory of Open Access Journals (Sweden)

    K.P.R. Chowdary and G. Rami Reddy *

    2012-04-01

    Full Text Available The objective of the study is to evaluate Olibanum resin, a natural resin polymer as matrix polymer for controlled release tablets and to design matrix tablets of diclofenac for controlled release. Matrix tablets of diclofenac were formulated employing Olibanum resin in different proportions of drug and polymer and the tablets were evaluated for drug release kinetics and mechanism .Two diluents namely lactose (water soluble and DCP (water insoluble were included in the formulations to assess their influence on drug release characteristics of olibanum resin matrix tablets. Matrix tablets were found t¬o be non- disint-egrating in water, acidic (pH 1.2 and alkaline (pH 7.4 fluids and were considered suitable for oral controlled release. Diclofenac release from the matrix tablets formulated was slow and spread over 24 h and depended on the concentration (% of olibanum resin in the matrix tablets and nature/type of diluent. As the concentration of olibanum resin in the matrix tablets was increased, drug release was decreased. Release was relatively faster with water soluble diluent lactose when compared to water insoluble diluent DCP at all concentrations of olibanum resin. Drug release from the tablets followed first order kinetics and followed non - Fickian (anomalous diffusion release mechanism. Good linear relationships were observed between percent polymer and release rate in each case. The results of the study thus indicated olibanum resin could be used as rate controlling matrix in design of controlled release tablets. Both water soluble and water insoluble diluents can be included in the olibanum resin matrix tablets without affecting its rate controlling efficiency. Matrix tablets formulated employing olibanum resin(DF2 are considered suitable for controlled release of diclofenac over 24 h (i.e. once-a-day administration.

  11. Preparation of photoreactive phospholipid polymer nanoparticles to immobilize and release protein by photoirradiation.

    Science.gov (United States)

    Chen, Weixin; Inoue, Yuuki; Ishihara, Kazuhiko

    2015-11-01

    Photoreactive and cytocompatible polymer nanoparticles for immobilizing and releasing proteins were prepared. A water-soluble and amphiphilic phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine (MPC)-co-n-butyl methacrylate (BMA)-co-4-(4-(1-methacryloyloxyethyl)-2-methoxy-5-nitrophenoxy) butyric acid (PL)) (PMB-PL) was synthesized. The PMB-PL underwent a cleavage reaction at the PL unit with photoirradiation at a wavelength of 365 nm. Additionally, the PMB-PL took polymer aggregate in aqueous medium and was used to modify the surface of biodegradable poly(L-lactic acid) (PLA) nanoparticle as an emulsifier. The morphology of the PMB-PL/PLA nanoparticle was spherical and approximately 130 nm in diameter. The carboxylic acid group in the PL unit could immobilize proteins by covalent bonding. The bound proteins were released by a photoinduced cleavage reaction. Within 60s, up to 90% of the immobilized proteins was released by photoirradiation. From these results and with an understanding of the fundamental properties of MPC polymers, we concluded that PMB-PL/PLA nanoparticles have the potential to be used as smart carriers to deliver proteins to biological systems, such as the inside of living cells.

  12. Nitroavidin as a ligand for the surface capture and release of biotinylated proteins.

    Science.gov (United States)

    Bolivar, Jowell G; Soper, Steven A; McCarley, Robin L

    2008-12-01

    Discussed here is the preparation, detailed purification, and evaluation of nitroavidin as a ligand for surface capture and release of biotinylated proteins. Avidin from chicken egg white was nitrated using dilute tetranitromethane solutions. UV-vis spectroscopy was used to show decreased binding of the biotin analogue, 2-(4'-hydroxyazobenzene)benzoic acid, HABA, to nitroavidin compared to binding of HABA to native avidin. From enzyme-linked immunosorbent assay (ELISA)-based assays of the modified avidin, it was found that there are approximately three tyrosine residues converted to nitrotyrosine out of the total four tyrosine residues in the protein tetramer. For the first time, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was used to demonstrate the point of nitration in nitroavidin as that of the tyrosine associated with the binding of biotin (Y33). From surface plasmon resonance spectroscopy (SPR) experiments, it is shown that biotin has less binding propensity to immobilized nitroavidin (K(D) = 4.4 +/- 1.9 x 10(-6) M) than immobilized avidin (K(D) < or = 10(-11) M). Importantly, the use of pH 10 carbonate buffer as eluent resulted in facile release of bound biotin from the nitroavidin-functionalized surfaces, allowing for readily regenerated biotin capture surfaces (reversible binding surfaces). These outcomes are important for the development of protein concentration methods directed at isolation of select proteins from a large population using gentle target protein isolation/release conditions.

  13. Control-release microcapsule of famotidine loaded biomimetic synthesized mesoporous silica nanoparticles: Controlled release effect and enhanced stomach adhesion in vitro.

    Science.gov (United States)

    Li, Jing; Wang, Hongyu; Yang, Baixue; Xu, Lu; Zheng, Nan; Chen, Hongtao; Li, Sanming

    2016-01-01

    In the present work, control-release microcapsule of famotidine (FMT) loaded biomimetic synthesized mesoporous silica nanoparticles (B-MSNs) was developed, and controlled release effect and stomach adhesion of this formulation in vitro were mainly investigated. B-MSN was previously synthesized and it was amorphous mesoporous nanoparticles with helical channels. Cytotoxicity of B-MSN was studied using human breast cancer cells (MCF-7) and the result indicated that cytotoxicity of B-MSN can be neglected. After loading FMT into B-MSN, specific surface area, pore volume and pore diameter of B-MSN were obviously reduced. In vitro dissolution test showed that B-MSN had the ability to slow down FMT release for 15 min. In order to prolong controlled release effect and remained the advantage of B-MSN (improve drug stability due to its rigid silica framework), the combined application of control-release microcapsule (using cellulose and hydroxypropyl methylcellulose K15M as excipients) with B-MSN was designed. It was obvious that newly designed formulation significantly controlled FMT release with Fickian diffusion mechanism and showed enhanced stomach adhesion in vitro, which has significant value in widening the application of B-MSN in formulation design.

  14. M protein is sufficient for assembly and release of Peste des petits ruminants virus-like particles.

    Science.gov (United States)

    Wang, Qiuxia; Ou, Changbo; Dou, Yongxi; Chen, Lei; Meng, Xuelian; Liu, Xingyou; Yu, Yan; Jiang, Jinqing; Ma, Jinyou; Zhang, Zhidong; Hu, Jianhe; Cai, Xuepeng

    2017-03-19

    Peste des petits ruminants virus (PPRV), belonging to paramyxoviruses, has six structure proteins (such as matrix protein (M), nucleocapsid proteins (N), fusion protein (F) and hemagglutinin protein (H)) and could cause high morbidity and mortality in sheep and goats. Although a vaccine strain of PPRV has been rescued and co-expression of M and N could yield PPRV-like particles, the roles of structure proteins in virion assembly and release have not been investigated in detail. In this study, plasmids carrying PPRV cDNA sequences encoding the N, M, H, and F proteins were expressed in Vero cells. The co-expression of all four proteins resulted in the release of virus-like particles (VLPs) with similar release efficiency to that of authentic virions. Moreover, the co-expression of M together with F also resulted in efficient VLPs release. In the absence of M protein, the expression of no combination of the other proteins resulted in particle release. In summary, a VLPs production system for PPRV has been established and M protein is necessary for promoting the assembly and release of VLPs, of which the predominant protein is M protein. Further study will be focused on the immunogenicity of the VLPs.

  15. The blend modification of EVA-150/starch and controlled-release of imazethapyr

    Institute of Scientific and Technical Information of China (English)

    TAI Li-min; ZHU Xiu-yun

    2008-01-01

    The EVA-150 and starch were extruded by extruding press and the bio-degra-dation composite material was prepared to use as the controlled-release matrix of imazethapyr. The compatibility and crystallinity of EVA-150/starch blending were analyzed by SEM and DSC, and the controlled-released performance of imazethapyr in the carriers was also investigated by UV analysis. The results show that EVA-150/starch composite matrix has the obvious controlled-released function and the release rates of imazethapyr all exceed 50% in the environment of pH4, pH7, or pH9 after nine days.

  16. The blend modification of EVA-150/starch and controlled-release of imazethapyr

    Institute of Scientific and Technical Information of China (English)

    TAI LI-min; ZHU Xiu-yun

    2008-01-01

    The EVA-150 and starch were extruded by extruding press and the bio-degradation composite material was prepared to use as the controlled-release matrix of imazethapyr.The compatibility and crystallinity of EVA-150/starch blending were analyzed by SEM and DSC,and the controlled-released performance of imazethapyr in the carriers was also investigated by UV analysis.The results show that EVA-150/starch composite matrix has the obvious controlled-released function and the release rates of imazethapyr all exceed 50% in the environment of pH4,pH7,or pH9 after nine days.

  17. Controlling benthic release of phosphorus in different Baltic Sea scales

    DEFF Research Database (Denmark)

    Pitkänen, Heikki; Bendtsen, Jørgen; Hansen, Jørgen L. S.

    The general aim of the PROPPEN project was to study whether it is possible to counteract near-bottom anoxia and excess benthic nutrient release ("internal loading") in the Baltic Sea by artificial oxygenation in cost-efficient and socio-economically beneficial ways. Two pilot sites were selected ...... to counteract anoxia and benthic release of nutrients in coastal marine conditions in the Baltic Sea. The project undertook monitoring of the pilot tests, modelling of effects at different scales, risk management, cost effectiveness and cost benefit analysis....

  18. Controlling benthic release of phosphorus in different Baltic Sea scales

    DEFF Research Database (Denmark)

    Pitkänen, Heikki; Bendtsen, Jørgen; Hansen, Jørgen L. S.;

    to counteract anoxia and benthic release of nutrients in coastal marine conditions in the Baltic Sea. The project undertook monitoring of the pilot tests, modelling of effects at different scales, risk management, cost effectiveness and cost benefit analysis.......The general aim of the PROPPEN project was to study whether it is possible to counteract near-bottom anoxia and excess benthic nutrient release ("internal loading") in the Baltic Sea by artificial oxygenation in cost-efficient and socio-economically beneficial ways. Two pilot sites were selected...

  19. On-chip assessment of the protein-release profile from 3D hydrogel arrays.

    Science.gov (United States)

    Oliveira, Mariana B; Mano, João F

    2013-02-19

    As the formation of healthy tissue and the treatment of several diseases are often dependent on an effective and prolonged action of bioactive agents, the delivery of molecules for therapeutic or induction purposes in a tissue is a common procedure. The correct administration of those agents is often dependent on tailored delivery mechanisms from hydrogel or polymeric matrixes. To the best of our knowledge, methods for the high-throughput monitoring of bioactive agent delivery are nonexistent. The methods for the in vitro monitoring of molecule release are expensive and laborious. As a simple alternative to these methods, we propose the imprinting of superhydrophobic biomimetic surfaces with ring-shaped transparent spots with concentric superhydrophobic millimetric regions to be used as bioactive agent release study platforms. We designed an array where polymeric precursors mixed with a growth-factor model protein labeled with a fluorescent tag could be dispensed in the concentric highly repellent regions and cross-linked afterward, generating a polymeric protein-loaded sphere. The ring-shaped region was then filled with a physiological-like fluid that covered the polymeric sphere. The acquisition of sequential images of each spot over time using microscopy methods allowed one to easily monitor the protein release by image-based fluorescence quantification. As the platform is easily adaptable and amenable for future automation in order to mimic standardized organ dynamics, we concluded that the device shows applicability for rapid and efficient in vitro bioactive agent release studies.

  20. Viral protein determinants of Lassa virus entry and release from polarized epithelial cells.

    Science.gov (United States)

    Schlie, Katrin; Maisa, Anna; Freiberg, Fabian; Groseth, Allison; Strecker, Thomas; Garten, Wolfgang

    2010-04-01

    The epithelium plays a key role in the spread of Lassa virus. Transmission from rodents to humans occurs mainly via inhalation or ingestion of droplets, dust, or food contaminated with rodent urine. Here, we investigated Lassa virus infection in cultured epithelial cells and subsequent release of progeny viruses. We show that Lassa virus enters polarized Madin-Darby canine kidney (MDCK) cells mainly via the basolateral route, consistent with the basolateral localization of the cellular Lassa virus receptor alpha-dystroglycan. In contrast, progeny virus was efficiently released from the apical cell surface. Further, we determined the roles of the glycoprotein, matrix protein, and nucleoprotein in directed release of nascent virus. To do this, a virus-like-particle assay was developed in polarized MDCK cells based on the finding that, when expressed individually, both the glycoprotein GP and matrix protein Z form virus-like particles. We show that GP determines the apical release of Lassa virus from epithelial cells, presumably by recruiting the matrix protein Z to the site of virus assembly, which is in turn essential for nucleocapsid incorporation into virions.

  1. Amnesia produced by altered release of neurotransmitters after intraamygdala injections of a protein synthesis inhibitor.

    Science.gov (United States)

    Canal, Clinton E; Chang, Qing; Gold, Paul E

    2007-07-24

    Amnesia produced by protein synthesis inhibitors such as anisomycin provides major support for the prevalent view that the formation of long-lasting memories requires de novo protein synthesis. However, inhibition of protein synthesis might disrupt other neural functions to interfere with memory formation. Intraamygdala injections of anisomycin before inhibitory avoidance training impaired memory in rats tested 48 h later. Release of norepinephrine (NE), dopamine (DA), and serotonin, measured at the site of anisomycin infusions, increased quickly by approximately 1,000-17,000%, far above the levels seen under normal conditions. NE and DA release later decreased far below baseline for several hours before recovering at 48 h. Intraamygdala injections of a beta-adrenergic receptor antagonist or agonist, each timed to blunt effects of increases and decreases in NE release after anisomycin, attenuated anisomycin-induced amnesia. In addition, similar to the effects on memory seen with anisomycin, intraamygdala injections of a high dose of NE before training impaired memory tested at 48 h after training. These findings suggest that altered release of neurotransmitters may mediate amnesia produced by anisomycin and, further, raise important questions about the empirical bases for many molecular theories of memory formation.

  2. Fabrication and Evaluation of Multilayer Nanofiber-Hydrogel Meshes with a Controlled Release Property

    Directory of Open Access Journals (Sweden)

    Rigumula Wu

    2015-07-01

    Full Text Available Controlled release drug delivery systems enable the sustained release of bioactive molecules, and increase bioavailability over an extended length of time. Biocompatible and biodegradable materials such as polycaprolactone (PCL nanofibers and alginate hydrogel play a significant role in designing controlled release systems. Prolonged release of bioactive molecules is observed when these polymer materials are used as matrices independently. However, there has not been a report in the literature that shows how different molecules are released at various rates over time. The goal of this study is to demonstrate a novel drug delivery system that has a property of releasing designated drugs at various rates over a defined length of time. We fabricated multilayer nanofiber-hydrogel meshes using electrospun PCL nanofiber and alginate hydrogel, and evaluated their controlled release properties. The multilayer meshes are composed of sandwiched layers of alternating PCL nanofibers and alginate hydrogel. Adenosine triphosphate (ATP, encapsulated in the designated hydrogel layers, is used as a mock drug for the release study. The exposed top layer of the meshes demonstrates a dramatically higher burst release and shorter release time compared to the deeper layers. Such properties of the different layers within the meshes can be employed to achieve the release of multiple drugs at different rates over a specified length of time.

  3. Biodegradable hollow fibres for the controlled release of drugs

    NARCIS (Netherlands)

    Schakenraad, J.M.; Oosterbaan, J.A.; Nieuwenhuis, P.; Molenaar, I.; Olijslager, J.; Potman, W.; Eenink, M.J.D.; Feijen, Jan

    1988-01-01

    Biodegradable hollow fibres of poly-l-lactic acid (PLLA) filled with a suspension of the contraceptive hormone levonorgestrel in castor oil were implanted subcutaneously in rats to study the rate of drug release, rate of biodegradation and tissue reaction caused by the implant. The in vivo drug

  4. A Remote Controlled Valve in Liposomes for Triggered Liposomal Release

    NARCIS (Netherlands)

    Koçer, Armağan

    2007-01-01

    In order to reduce the toxicity and increase the efficacy of drugs, there is a need for smart drug delivery systems. Liposomes are one of the promising tools for this purpose. An ideal liposomal delivery system should be stable, long-circulating, accumulate at the target site and release its drug in

  5. Control of oxygen release from peroxides using polymers

    NARCIS (Netherlands)

    Steg, Hilde; Buizer, Arina T.; Woudstra, Willem; Veldhuizen, Albert G.; Bulstra, Sjoerd K.; Grijpma, Dirk W.; Kuijer, Roel

    An important limitation in cell therapy for the regeneration of tissue is the initial lack of oxygen. After implantation of large 3D cell-seeded structures, cells die rather than contribute to tissue regenerating. Here we've tested oxygen-releasing materials to improve cell survival and growth after

  6. Control of oxygen release from peroxides using polymers

    NARCIS (Netherlands)

    Steg, Hilde; Buizer, A.T.; Woudstra, W.; Veldhuizen, A.G.; Bulstra, S.K.; Grijpma, Dirk W.; Kuijer, R.

    2015-01-01

    An important limitation in cell therapy for the regeneration of tissue is the initial lack of oxygen. After implantation of large 3D cell-seeded structures, cells die rather than contribute to tissue regenerating. Here we’ve tested oxygen-releasing materials to improve cell survival and growth after

  7. Biodegradable hollow fibres for the controlled release of drugs

    NARCIS (Netherlands)

    Schakenraad, J.M.; Oosterbaan, J.A.; Nieuwenhuis, P.; Molenaar, I.; Olijslager, J.; Potman, W.; Eenink, M.J.D.; Feijen, J.

    1988-01-01

    Biodegradable hollow fibres of poly-l-lactic acid (PLLA) filled with a suspension of the contraceptive hormone levonorgestrel in castor oil were implanted subcutaneously in rats to study the rate of drug release, rate of biodegradation and tissue reaction caused by the implant. The in vivo drug rele

  8. Control of oxygen release from peroxides using polymers

    NARCIS (Netherlands)

    Steg, Hilde; Buizer, A.T.; Woudstra, W.; Veldhuizen, A.G.; Bulstra, S.K.; Grijpma, D.W.; Kuijer, R.

    2015-01-01

    An important limitation in cell therapy for the regeneration of tissue is the initial lack of oxygen. After implantation of large 3D cell-seeded structures, cells die rather than contribute to tissue regenerating. Here we’ve tested oxygen-releasing materials to improve cell survival and growth after

  9. Concerning Workload Control and Order Release : The Pre-Shop Pool Sequencing Decision

    NARCIS (Netherlands)

    Thürer, Matthias; Land, Martin J.; Stevenson, Mark; Fredendall, Lawrence D.; Godinho Filho, Moacir

    2015-01-01

    Every production planning concept that incorporates controlled order release will initially withhold jobs from the shop floor and create a pre-shop pool. Order release is a key component of the Workload Control concept that aims to maintain work-in-process within limits while ensuring due dates are

  10. Release retardation of model protein on polyelectrolyte-coated PLGA nano- and microparticles.

    Directory of Open Access Journals (Sweden)

    Chandra Nugraha

    Full Text Available PEM capsules have been proposed for vehicles of drug microencapsulation, with the release triggered by pH, salt, magnetic field, or light. When built on another carrier encapsulating drugs, such as nanoparticles, it could provide additional release barrier to the releasing drug, providing further control to drug release. Although liposomes have received considerable attention with PEM coating for sustained drug release, similar results employing PEM built on poly(lactic-co-lycolic acid (PLGA particles is scant. In this work, we demonstrate that the build-up pH and polyelectrolyte pairs of PEM affect the release retardation of BSA from PLGA particles. PAH/PSS pair, the most commonly used polyelectrolyte pair, was used in comparison with PLL/DES. In addition, we also demonstrate that the release retardation effect of PEM-coated PLGA particles diminishes as the particle size increases. We attribute this to the diminishing relative thickness of the PEM coating with respect to the size of the particle as the particle size increases, reducing the diffusional resistance of the PEM.

  11. Release retardation of model protein on polyelectrolyte-coated PLGA nano- and microparticles.

    Science.gov (United States)

    Nugraha, Chandra; Bora, Meghali; Venkatraman, Subbu S

    2014-01-01

    PEM capsules have been proposed for vehicles of drug microencapsulation, with the release triggered by pH, salt, magnetic field, or light. When built on another carrier encapsulating drugs, such as nanoparticles, it could provide additional release barrier to the releasing drug, providing further control to drug release. Although liposomes have received considerable attention with PEM coating for sustained drug release, similar results employing PEM built on poly(lactic-co-lycolic acid) (PLGA) particles is scant. In this work, we demonstrate that the build-up pH and polyelectrolyte pairs of PEM affect the release retardation of BSA from PLGA particles. PAH/PSS pair, the most commonly used polyelectrolyte pair, was used in comparison with PLL/DES. In addition, we also demonstrate that the release retardation effect of PEM-coated PLGA particles diminishes as the particle size increases. We attribute this to the diminishing relative thickness of the PEM coating with respect to the size of the particle as the particle size increases, reducing the diffusional resistance of the PEM.

  12. Application of waterborne acrylic emulsions in coated controlled release fertilizer using reacted layer technology

    Institute of Scientific and Technical Information of China (English)

    Yazhen Shen; Cong Zhao; Jianmin Zhou; Changwen Du

    2015-01-01

    Waterborne acrylic emulsions modified with organic siloxanes and aziridine crosslinker were synthesized and applied as coating of controlled release fertilizer. The free films were characterized and the nutrient release pro-files of the coated fertilizers were determined. The results show that methyl silicone oil and methylsilanolate so-dium could not improve water resistance performance and glass transition temperature Tg of coatings, while the firmness is enhanced. Aziridine crosslinker improves the water resistance performance, firmness and Tg. Incorpo-ration of methyl silicone oil and aziridine crosslinker gives an excellent aqueous acrylic emulsion for coated con-trol ed release fertilizer, with the 30-day cumulative nutrient release reduced to 16%and an estimated nutrient release duration over 190 days. Therefore, this waterborne coating is promising to meet the requirements for controlled release of nutrient and environmental protection.

  13. Optimized loading and sustained release of hydrophilic proteins from internally nanostructured particles.

    Science.gov (United States)

    Chemelli, Angela; Maurer, Manuela; Geier, Roman; Glatter, Otto

    2012-12-11

    In this study, we demonstrate that emulsified microemulsions and micellar cubosomes are suitable as sustained delivery vehicles for water-soluble proteins. Through structural modifications, the loading efficiency of two model proteins, namely bovine serum albumin (BSA) and cytochrome c could be remarkably increased. A procedure for preparing these particles loaded with optimized amounts of sensitive substances is presented. Loading and dispersion at low temperatures is performed in two successive steps. First, a water-in-oil microemulsion is loaded with the proteins. Subsequently, this phase is dispersed in water resulting in particles with microemulsion and micellar cubic internal structure and a size of approximately 620 nm. This two-step method ensures optimal loading of the particles with the proteins. These nanostructured particles are able to sustain the release of the water-soluble BSA and cytochrome c. Within one day, less than 10% of BSA and 15% of cytochrome c are released. The release rate of cytochrome c is influenced by the nanostructure of the particles.

  14. Controlled Release of Collagen-Binding SDF-1α Improves Cardiac Function after Myocardial Infarction by Recruiting Endogenous Stem Cells.

    Science.gov (United States)

    Sun, Jie; Zhao, Yannan; Li, Qingguo; Chen, Bing; Hou, Xianglin; Xiao, Zhifeng; Dai, Jianwu

    2016-05-26

    Stromal cell-derived factor-1α (SDF-1α) is a well-characterized chemokine that mobilizes stem cells homing to the ischemic heart, which is beneficial for cardiac regeneration. However, clinically administered native SDF-1α diffuses quickly, thus decreasing its local concentration, and results in side effects. Thus, a controlled release system for SDF-1α is required to produce an effective local concentration in the ischemic heart. In this study, we developed a recombinant chemokine, consisting of SDF-1α and a collagen-binding domain, which retains both the SDF-1α and collagen-binding activity (CBD-SDF-1α). In an in vitro assay, CBD-SDF-1α could specifically bind to a collagen gel and achieve sustained release. An intramyocardial injection of CBD-SDF-1α after acute myocardial infarction demonstrated that the protein was largely tethered in the ischemic area and that controlled release had been achieved. Furthermore, CBD-SDF-1α enhanced the recruitment of c-kit positive (c-kit(+)) stem cells, increased capillary density and improved cardiac function, whereas NAT-SDF-1α had no such beneficial effects. Our findings demonstrate that CBD-SDF-1α can specifically bind to collagen and achieve controlled release both in vitro and in vivo. Local delivery of this protein could mobilize endogenous stem cells homing to the ischemic heart and improve cardiac function after myocardial infarction.

  15. Controlled drug release on amine functionalized spherical MCM-41

    Science.gov (United States)

    Szegedi, Agnes; Popova, Margarita; Goshev, Ivan; Klébert, Szilvia; Mihály, Judit

    2012-10-01

    MCM-41 silica with spherical morphology and small particle sizes (100 nm) was synthesized and modified by post-synthesis method with different amounts of 3-aminopropyltriethoxysilane (APTES). A comparative study of the adsorption and release of a model drug, ibuprofen, was carried out. The modified and drug loaded mesoporous materials were characterized by XRD, TEM, N2 physisorption, elemental analysis, thermal analysis and FT-IR spectroscopy. A new method was developed for the quantitative determination of amino groups in surface modified mesoporous materials by the ninhydrin reaction. Good correlation was found between the amino content of the MCM-41 materials determined by the ninhydrin method and their ibuprofen adsorption capacity. Amino modification resulted in high degree of ibuprofen loading and slow release rate in comparison to the parent non-modified MCM-41.

  16. Gastrin release: Antrum microdialysis reveals a complex neural control

    DEFF Research Database (Denmark)

    Ericsson, P; Håkanson, R; Rehfeld, Jens F.;

    2010-01-01

    in serum regardless of the prandial state. The rats were conscious during microdialysis except when subjected to electrical vagal stimulation. Acid blockade (omeprazole treatment of freely fed rats for 4 days), or bilateral sectioning of the abdominal vagal trunks (fasted, 3 days post-op.), raised...... the gastrin concentration in blood as well as microdialysate. The high gastrin concentration following omeprazole treatment was not affected by vagotomy. Vagal excitation stimulated the G cells: electrical vagal stimulation and pylorus ligation (fasted rats) raised the gastrin concentration transiently...... microdialysate gastrin concentration in omeprazole-treated rats by 65%. We conclude that activated gastrin release, unlike basal gastrin release, is highly dependent on a neural input: 1) Vagal excitation has a transient stimulating effect on the G cells. The transient nature of the response suggests...

  17. Formation, release and control of dioxins in cement kilns.

    Science.gov (United States)

    Karstensen, Kåre Helge

    2008-01-01

    Co-processing of hazardous wastes in cement kilns have for decades been thought to cause increased emissions of PCDD/PCDFs--a perception that has been evaluated in this study. Hundreds of PCDD/PCDF measurements conducted by the cement industry and others in the last few years, on emissions and solid materials, as well as recent test burns with hazardous wastes in developing countries do not support this perception. Newer data has been compared with older literature data and shows in particular that many emission factors have to be reconsidered. Early emission factors for cement kilns co-processing hazardous waste, which are still used in inventories, are shown to be too high compared with actual measurements. Less than 10 years ago it was believed that the cement industry was the main contributor of PCDD/PCDFs to air; data collected in this study indicates however that the industry contributes with less than 1% of total emissions to air. The Stockholm Convention on POPs presently ratified by 144 parties, classifies cement kilns co-processing hazardous waste as a source category having the potential for comparatively high formation and release of PCDD/PCDFs. This classification is based on early investigations from the 1980s and 1990s where kilns co-processing hazardous waste had higher emissions compared to those that did not burn hazardous waste. However, the testing of these kilns was often done under worst case scenario conditions known to favour PCDD/PCDF formation. More than 2000 PCDD/PCDF cement kiln measurements have been evaluated in this study, representing most production technologies and waste feeding scenarios. They generally indicate that most modern cement kilns co-processing waste today can meet an emission level of 0.1ngI-TEQ/m(3), when well managed and operated. In these cases, proper and responsible use of waste including organic hazardous waste to replace parts of the fossil fuel does not seem to increase formation of PCDD/PCDFs. Modern preheater

  18. Pneumocystis carinii major surface glycoprotein induces interleukin-8 and monocyte chemoattractant protein-1 release from a human alveolar epithelial cell line

    DEFF Research Database (Denmark)

    Benfield, T L; Lundgren, Bettina; Shelhamer, J H

    1999-01-01

    (IL-8) and monocyte chemoattractant protein-1 (MCP-1) from an alveolar epithelial cell line (A549). RESULTS: Incubation of A549 cells with MSG in concentrations from 0.4 to 10 microg mL-1 for 24 h caused dose-dependent increases in IL-8 release (3.4-fold above control, P

  19. Sandwich Structure-like Meshes Fabricated via Electrospinning for Controllable Release of Zoledronic Acid

    Institute of Scientific and Technical Information of China (English)

    LU Jian; LIU Jian-guo; SONG Xiao-feng; CHEN Xue-si; WU Xiao-dong

    2011-01-01

    Novel sandwich structure-like nanofiber multilayered meshes were fabricated via electrospinning. The purpose of the present work was to control zoledronic acid release via the novel structure of sandwich structure-like meshes. The in vitro release experiments reveal that the drug release speed and initial burst release were controllable by adjusting the thicknesses of electrospun barrier mesh and drug-loaded mesh. Compared with those of other drug delivery systems, the main advantages of the sandwich structure-like fiber meshes are facile preparation conditions and the generality for hydrophobic and hydrophilic pharmaceuticals.

  20. 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....

  1. Phenobarbital loaded microemulsion: development, kinetic release and quality control

    Directory of Open Access Journals (Sweden)

    Kayo Alves Figueiredo

    Full Text Available ABSTRACT This study aimed to obtain and characterize a microemulsion (ME containing phenobarbital (PB. The PB was incorporated in the proportion of 5% and 10% in a microemulsion system containing Labrasol(r, ethanol, isopropyl myristate and purified water. The physicochemical characterization was performed and the primary stability of the ME was evaluated. An analytical method was developed using spectrophotometry in UV = 242 nm. The kinetics of the in vitro release (Franz model of the ME and the emulsion (EM containing PB was evaluated. The incorporation of PB into ME at concentrations of 5 and 10% did not change pH and resistance to centrifugation. There was an increase in particle size, a decrease of conductivity and a change in the refractive index in relation to placebo ME. The ME remained stable in preliminary stability tests. The analytical method proved to be specific, linear, precise, accurate and robust. Regarding the kinetics of the in vitro release, ME obtained an in vitro release profile greater than the EM containing PB. Thus, the obtained ME has a potential for future transdermal application, being able to compose a drug delivery system for the treatment of epilepsy.

  2. 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.

  3. A bacterial protein enhances the release and efficacy of liposomal cancer drugs.

    Science.gov (United States)

    Cheong, Ian; Huang, Xin; Bettegowda, Chetan; Diaz, Luis A; Kinzler, Kenneth W; Zhou, Shibin; Vogelstein, Bert

    2006-11-24

    Clostridium novyi-NT is an anaerobic bacterium that can infect hypoxic regions within experimental tumors. Because C. novyi-NT lyses red blood cells, we hypothesized that its membrane-disrupting properties could be exploited to enhance the release of liposome-encapsulated drugs within tumors. Here, we show that treatment of mice bearing large, established tumors with C. novyi-NT plus a single dose of liposomal doxorubicin often led to eradication of the tumors. The bacterial factor responsible for the enhanced drug release was identified as a previously unrecognized protein termed liposomase. This protein could potentially be incorporated into diverse experimental approaches for the specific delivery of chemotherapeutic agents to tumors.

  4. Counterions release from electrostatic complexes of polyelectrolytes and proteins of opposite charge : a direct measurement

    CERN Document Server

    Gummel, Jérémie; Boué, François

    2009-01-01

    Though often considered as one of the main driving process of the complexation of species of opposite charges, the release of counterions has never been experimentally directly measured on polyelectrolyte/proteins complexes. We present here the first structural determination of such a release by Small Angle Neutron Scattering in complexes made of lysozyme, a positively charged protein and of PSS, a negatively charged polyelectrolyte. Both components have the same neutron density length, so their scattering can be switched off simultaneously in an appropriate "matching" solvent; this enables determination of the spatial distribution of the single counterions within the complexes. The counterions (including the one subjected to Manning condensation) are expelled from the cores where the species are at electrostatic stoichiometry.

  5. Controlled release of folic acid through liquid-crystalline folate nanoparticles.

    Science.gov (United States)

    Misra, Rahul; Katyal, Henna; Mohanty, Sanat

    2014-11-01

    The present study explores folate nanoparticles as nano-carriers for controlled drug delivery. Cross-linked nanoparticles of liquid crystalline folates are composed of ordered stacks. This paper shows that the folate nanoparticles can be made with less than 5% loss in folate ions. In addition, this study shows that folate nanoparticles can disintegrate in a controlled fashion resulting in controlled release of the folate ions. Release can be controlled by the size of nanoparticles, the extent of cross-linking and the choice of cross-linking cation. The effect of different factors like agitation, pH, and temperature on folate release was also studied. Studies were also carried out to show the effect of release medium and role of ions in the release medium on disruption of folate assembly.

  6. Release of free amino acids upon oxidation of peptides and proteins by hydroxyl radicals.

    Science.gov (United States)

    Liu, Fobang; Lai, Senchao; Tong, Haijie; Lakey, Pascale S J; Shiraiwa, Manabu; Weller, Michael G; Pöschl, Ulrich; Kampf, Christopher J

    2017-03-01

    Hydroxyl radical-induced oxidation of proteins and peptides can lead to the cleavage of the peptide, leading to a release of fragments. Here, we used high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) and pre-column online ortho-phthalaldehyde (OPA) derivatization-based amino acid analysis by HPLC with diode array detection and fluorescence detection to identify and quantify free amino acids released upon oxidation of proteins and peptides by hydroxyl radicals. Bovine serum albumin (BSA), ovalbumin (OVA) as model proteins, and synthetic tripeptides (comprised of varying compositions of the amino acids Gly, Ala, Ser, and Met) were used for reactions with hydroxyl radicals, which were generated by the Fenton reaction of iron ions and hydrogen peroxide. The molar yields of free glycine, aspartic acid, asparagine, and alanine per peptide or protein varied between 4 and 55%. For protein oxidation reactions, the molar yields of Gly (∼32-55% for BSA, ∼10-21% for OVA) were substantially higher than those for the other identified amino acids (∼5-12% for BSA, ∼4-6% for OVA). Upon oxidation of tripeptides with Gly in C-terminal, mid-chain, or N-terminal positions, Gly was preferentially released when it was located at the C-terminal site. Overall, we observe evidence for a site-selective formation of free amino acids in the OH radical-induced oxidation of peptides and proteins, which may be due to a reaction pathway involving nitrogen-centered radicals.

  7. Halloysite Nanotube Composited Thermo-responsive Hydrogel System for Controlled-release

    Institute of Scientific and Technical Information of China (English)

    林茜; 巨晓洁; 谢锐; 江明月; 魏竭; 褚良银

    2013-01-01

    Halloysite nanotube-composited thermo-responsive hydrogel system has been successfully developed for controlled drug release by copolymerization of N-isopropylacrylamide (NIPAM) with silane-modified halloysite nanotubes (HNT) through thermally initiated free-radical polymerization. With methylene blue as a model drug, thermo-responsive drug release results demonstrate that the drug release from the nanotubes in the composited hy-drogel can be well controlled by manipulating the environmental temperature. When the hydrogel network is swol-len at temperature below the lower critical solution temperature (LCST), drug releases steadily from lumens of the embedded nanotubes, whereas the drug release stops when hydrogel shrinks at temperature above the LCST. The release of model drug from the HNT-composited hydrogel matches well with its thermo-responsive volume phase transition, and shows characteristics of well controlled release. The design strategy and release results of the pro-posed novel HNT-composited thermo-responsive hydrogel system provide valuable guidance for designing respon-sive nanocomposites for controlled-release of active agents.

  8. A CO2-switchable polymer brush for reversible capture and release of proteins.

    Science.gov (United States)

    Kumar, Surjith; Tong, Xia; Dory, Yves L; Lepage, Martin; Zhao, Yue

    2013-01-01

    We report on a polymer brush that can be switched between extended (hydrated) and collapsed (dehydrated) chain conformational states just by passing CO(2) and an inert gas like N(2) in solution alternately. This conformational change allows for reversible adsorption and release of a protein. In contrast to adding acids and bases for pH change, using gases as the trigger makes it possible to repeat the switching cycle many times without salt accumulation.

  9. Targeting protein-protein interactions for parasite control.

    Directory of Open Access Journals (Sweden)

    Christina M Taylor

    Full Text Available Finding new drug targets for pathogenic infections would be of great utility for humanity, as there is a large need to develop new drugs to fight infections due to the developing resistance and side effects of current treatments. Current drug targets for pathogen infections involve only a single protein. However, proteins rarely act in isolation, and the majority of biological processes occur via interactions with other proteins, so protein-protein interactions (PPIs offer a realm of unexplored potential drug targets and are thought to be the next-generation of drug targets. Parasitic worms were chosen for this study because they have deleterious effects on human health, livestock, and plants, costing society billions of dollars annually and many sequenced genomes are available. In this study, we present a computational approach that utilizes whole genomes of 6 parasitic and 1 free-living worm species and 2 hosts. The species were placed in orthologous groups, then binned in species-specific orthologous groups. Proteins that are essential and conserved among species that span a phyla are of greatest value, as they provide foundations for developing broad-control strategies. Two PPI databases were used to find PPIs within the species specific bins. PPIs with unique helminth proteins and helminth proteins with unique features relative to the host, such as indels, were prioritized as drug targets. The PPIs were scored based on RNAi phenotype and homology to the PDB (Protein DataBank. EST data for the various life stages, GO annotation, and druggability were also taken into consideration. Several PPIs emerged from this study as potential drug targets. A few interactions were supported by co-localization of expression in M. incognita (plant parasite and B. malayi (H. sapiens parasite, which have extremely different modes of parasitism. As more genomes of pathogens are sequenced and PPI databases expanded, this methodology will become increasingly

  10. Protein Adsorption into Mesopores: A Combination of Electrostatic Interaction, Counterion Release and van der Waals Forces

    CERN Document Server

    Moerz, Sebastian T

    2015-01-01

    Bovine heart cytochrome c has been immobilized into the mesoporous silica host material SBA-15 in both its native folded and urea-unfolded state. The comparison of the two folding states' behavior casts doubt on the commonly used explanation of cytochrome c adsorption, i.e. the electrostatic interaction model. A detailed investigation of the protein binding as a function of pH and ionic strength of the buffer solution reveals the complex nature of the protein-silica interaction. Electrostatic interaction, van der Waals forces and entropic contributions by counterion release each contribute to adsorption on the silica pore walls.

  11. Deletion of Corticotropin-releasing Factor Binding Protein Selectively Impairs Maternal, but not Intermale Aggression

    OpenAIRE

    Gammie, Stephen C.; Seasholtz, Audrey F.; Stevenson, Sharon A.

    2008-01-01

    Corticotropin-releasing factor (CRF) binding protein (CRF-BP) is a secreted protein that acts to bind and limit the activity of the neuropeptides, CRF and urocortin (Ucn) 1. We previously selected for high maternal defense (protection of offspring) in mice and found CRF-BP to be elevated in the CNS of selected mice. We also previously determined that both CRF and Ucn 1 are potent inhibitors of offspring protection when administered centrally. Thus, elevated CRF-BP could promote defense by lim...

  12. Preparation and characterization of controlled release matrices based on novel seaweed interpolyelectrolyte complexes.

    Science.gov (United States)

    Prado, Héctor J; Matulewicz, María C; Bonelli, Pablo R; Cukierman, Ana L

    2012-06-15

    Novel interpolyelectrolyte complexes (IPECs) between naturally sulfated polysaccharides of the seaweed Polysiphonia nigrescens (PN) and cationized agaroses (CAG) and Eudragit E (EE) were prepared using an organic solvent free process, characterized, and explored for controlled drug release. Tablets containing model drug ibuprofen and IPECs were prepared by direct compression. Drug release in acid medium was low owing to the low solubility of ibuprofen in that condition and to the matrix action. Zero order drug release was determined in the buffer stage (pH=6.8), with Fickian diffusion predominating over relaxation during the initial phases. Relaxation appears to increase along the release process and even overcomes diffusion for some systems. Drug release profiles could be controlled by varying the content of IPECs in the tablets. Also, the change in molecular weight and the degree of substitution of the components allowed altering the release profiles.

  13. Sustained release of bone morphogenetic protein 2 via coacervate improves the osteogenic potential of muscle-derived stem cells.

    Science.gov (United States)

    Li, Hongshuai; Johnson, Noah Ray; Usas, Arvydas; Lu, Aiping; Poddar, Minakshi; Wang, Yadong; Huard, Johnny

    2013-09-01

    Muscle-derived stem cells (MDSCs) isolated from mouse skeletal muscle by a modified preplate technique exhibit long-term proliferation, high self-renewal, and multipotent differentiation capabilities in vitro. MDSCs retrovirally transduced to express bone morphogenetic proteins (BMPs) can differentiate into osteocytes and chondrocytes and enhance bone and articular cartilage repair in vivo, a feature that is not observed with nontransduced MDSCs. These results emphasize that MDSCs require prolonged exposure to BMPs to undergo osteogenic and chondrogenic differentiation. A sustained BMP protein delivery approach provides a viable and potentially more clinically translatable alternative to genetic manipulation of the cells. A unique growth factor delivery platform comprised of native heparin and a synthetic polycation, poly(ethylene argininylaspartate diglyceride) (PEAD), was used to bind, protect, and sustain the release of bone morphogenetic protein-2 (BMP2) in a temporally and spatially controlled manner. Prolonged exposure to BMP2 released by the PEAD:heparin delivery system promoted the differentiation of MDSCs to an osteogenic lineage in vitro and induced the formation of viable bone at an ectopic site in vivo. This new strategy represents an alternative approach for bone repair mediated by MDSCs while bypassing the need for gene therapy.

  14. Controlled Release of Salicylic Acid from Biodegradable Cross-Linked Polyesters.

    Science.gov (United States)

    Dasgupta, Queeny; Chatterjee, Kaushik; Madras, Giridhar

    2015-09-08

    The purpose of this work was to develop a family of cross-linked poly(xylitol adipate salicylate)s with a wide range of tunable release properties for delivering pharmacologically active salicylic acid. The synthesis parameters and release conditions were varied to modulate polyester properties and to understand the mechanism of release. Varying release rates were obtained upon longer curing (35% in the noncured polymer to 10% in the cured polymer in 7 days). Differential salicylic acid loading led to the synthesis of polymers with variable cross-linking and the release could be tuned (100% release for the lowest loading to 30% in the highest loading). Controlled release was monitored by changing various factors, and the release profiles were dependent on the stoichiometric composition, pH, curing time, and presence of enzyme. The polymer released a combination of salicylic acid and disalicylic acid, and the released products were found to be nontoxic. Minimal hemolysis and platelet activation indicated good blood compatibility. These polymers qualify as "bioactive" and "resorbable" and can, therefore, find applications as immunomodulatory resorbable biomaterials with tunable release properties.

  15. Lysine-based polycation:heparin coacervate for controlled protein delivery.

    Science.gov (United States)

    Johnson, Noah Ray; Ambe, Trisha; Wang, Yadong

    2014-01-01

    Polycations have good potential as carriers of proteins and genetic material. However, poor control over the release rate and safety issues currently limit their use as delivery vehicles. Here we introduce a new lysine-based polycation, poly(ethylene lysinylaspartate diglyceride) (PELD), which exhibits high cytocompatibility. PELD self-assembles with the biological polyanion heparin into a coacervate that incorporates proteins with high loading efficiency. Coacervates of varying surface charge were obtained by simple alteration of the PELD:heparin ratio and resulted in diverse release profiles of the model protein bovine serum albumin. Therefore, coacervate charge represents a direct means of control over release rate and duration. The PELD coacervate also rapidly adsorbed onto a porous polymeric scaffold, demonstrating potential use in tissue engineering applications. This coacervate represents a safe and tunable protein delivery system for biomedical applications.

  16. ELKS controls the pool of readily releasable vesicles at excitatory synapses through its N-terminal coiled-coil domains.

    Science.gov (United States)

    Held, Richard G; Liu, Changliang; Kaeser, Pascal S

    2016-06-02

    In a presynaptic nerve terminal, synaptic strength is determined by the pool of readily releasable vesicles (RRP) and the probability of release (P) of each RRP vesicle. These parameters are controlled at the active zone and vary across synapses, but how such synapse specific control is achieved is not understood. ELKS proteins are enriched at vertebrate active zones and enhance P at inhibitory hippocampal synapses, but ELKS functions at excitatory synapses are not known. Studying conditional knockout mice for ELKS, we find that ELKS enhances the RRP at excitatory synapses without affecting P. Surprisingly, ELKS C-terminal sequences, which interact with RIM, are dispensable for RRP enhancement. Instead, the N-terminal ELKS coiled-coil domains that bind to Liprin-α and Bassoon are necessary to control RRP. Thus, ELKS removal has differential, synapse-specific effects on RRP and P, and our findings establish important roles for ELKS N-terminal domains in synaptic vesicle priming.

  17. Coordinated coupling control of tethered space robot using releasing characteristics of space tether

    Science.gov (United States)

    Huang, Panfeng; Zhang, Fan; Xu, Xiudong; Meng, Zhongjie; Liu, Zhengxiong; Hu, Yongxin

    2016-04-01

    Tethered space robot (TSR) is a new concept of space robot, which is released from the platform satellite, and retrieved via connected tether after space debris capture. In this paper, we propose a new coordinate control scheme for optimal trajectory and attitude tracking, and use releasing motor torque to instead the tension force, since it is difficult to track in practical. Firstly, the 6-DOF dynamics model of TSR is derived, in which the dynamics of tether releasing system is taken into account. Then, we propose and design the coordinated coupled controller, which is composed of a 6-DOF sliding mode controller and a PD controller tether's releasing. Thrust is treated as control input of the 6-DOF sliding mode controller to control the in-plane and out-of-plane angle of the tether and attitude angles of the TSR. The torque of releasing motor is used as input of PD controller, which controls the length rate of space tether. After the verification of the control scheme, finally, the simulation experiment is presented in order to validate the effectiveness of this control method. The results show that TSR can track the optimal approaching trajectory accurately. Simultaneously, the attitude angles can be changed to the desired attitude angles in control period, and the terminal accuracy is ±0.3°.

  18. Genetic noise control via protein oligomerization

    Energy Technology Data Exchange (ETDEWEB)

    Ghim, C; Almaas, E

    2008-06-12

    Gene expression in a cell entails random reaction events occurring over disparate time scales. Thus, molecular noise that often results in phenotypic and population-dynamic consequences sets a fundamental limit to biochemical signaling. While there have been numerous studies correlating the architecture of cellular reaction networks with noise tolerance, only a limited effort has been made to understand the dynamical role of protein-protein associations. We have developed a fully stochastic model for the positive feedback control of a single gene, as well as a pair of genes (toggle switch), integrating quantitative results from previous in vivo and in vitro studies. In particular, we explicitly account for the fast protein binding-unbinding kinetics, RNA polymerases, and the promoter/operator sequences of DNA. We find that the overall noise-level is reduced and the frequency content of the noise is dramatically shifted to the physiologically irrelevant high-frequency regime in the presence of protein dimerization. This is independent of the choice of monomer or dimer as transcription factor and persists throughout the multiple model topologies considered. For the toggle switch, we additionally find that the presence of a protein dimer, either homodimer or heterodimer, may significantly reduce its intrinsic switching rate. Hence, the dimer promotes the robust function of bistable switches by preventing the uninduced (induced) state from randomly being induced (uninduced). The specific binding between regulatory proteins provides a buffer that may prevent the propagation of fluctuations in genetic activity. The capacity of the buffer is a non-monotonic function of association-dissociation rates. Since the protein oligomerization per se does not require extra protein components to be expressed, it provides a basis for the rapid control of intrinsic or extrinsic noise. The stabilization of phenotypically important toggle switches, and nested positive feedback loops in

  19. Sustained and controlled release of lipophilic drugs from a self-assembling amphiphilic peptide hydrogel

    DEFF Research Database (Denmark)

    Briuglia, Maria-Lucia; Urquhart, Andrew; Lamprou, Dimitrios A.

    2014-01-01

    . In this work, we have investigated the diffusion properties of Pindolol, Quinine and Timolol maleate from RADA16 in PBS and in BSS-PLUS at 37°C. A sustained, controlled, reproducible and efficient drug release has been detected for all the systems, which allows to understand the dependence of release kinetics...

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. Pneumocystis carinii major surface glycoprotein induces interleukin-8 and monocyte chemoattractant protein-1 release from a human alveolar epithelial cell line

    DEFF Research Database (Denmark)

    Benfield, T L; Lundgren, Bettina; Shelhamer, J H;

    1999-01-01

    (IL-8) and monocyte chemoattractant protein-1 (MCP-1) from an alveolar epithelial cell line (A549). RESULTS: Incubation of A549 cells with MSG in concentrations from 0.4 to 10 microg mL-1 for 24 h caused dose-dependent increases in IL-8 release (3.4-fold above control, P ..., suggesting that MSG stimulates A549 cells in part through carbohydrate moieties. Dexamethasone significantly inhibited MSG-induced IL-8 release in concentrations of 10-6-10-8 mol L-1 compared with control experiments (P

  5. GDP Release Preferentially Occurs on the Phosphate Side in Heterotrimeric G-proteins

    Science.gov (United States)

    Louet, Maxime; Martinez, Jean; Floquet, Nicolas

    2012-01-01

    After extra-cellular stimulation of G-Protein Coupled Receptors (GPCRs), GDP/GTP exchange appears as the key, rate limiting step of the intracellular activation cycle of heterotrimeric G-proteins. Despite the availability of a large number of X-ray structures, the mechanism of GDP release out of heterotrimeric G-proteins still remains unknown at the molecular level. Starting from the available X-ray structure, extensive unconstrained/constrained molecular dynamics simulations were performed on the complete membrane-anchored Gi heterotrimer complexed to GDP, for a total simulation time overcoming 500 ns. By combining Targeted Molecular Dynamics (TMD) and free energy profiles reconstruction by umbrella sampling, our data suggest that the release of GDP was much more favored on its phosphate side. Interestingly, upon the forced extraction of GDP on this side, the whole protein encountered large, collective motions in perfect agreement with those we described previously including a domain to domain motion between the two ras-like and helical sub-domains of Gα. PMID:22829757

  6. 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.

  7. Expected shortage based pre-release strategy for reservoir flood control

    Science.gov (United States)

    Chou, Frederick N.-F.; Wu, Chia-Wen

    2013-08-01

    In Taiwan, an increase in the frequency of severe flooding over the past decade has prompted demand for improved reservoir operation to control flood-related damage. Flood protection of reservoir can be enhanced by pre-releasing its storage to more adequately accommodate an impending flood. A procedure is proposed in this paper to evaluate the impact of pre-releases of flood control operation on water supply. A basic criterion used is that the pre-release of reservoir storage should not cause intolerable increment of water shortage risk. The shortage risks for different pre-release scenarios are simulated according to the uncertainties of storm rainfall and post-flood ordinary inflow till the end of next dry season. Two operational objectives are provided to help determining the target pre-released level. One of which identifies the minimum allowable pre-released threshold. The other seeks the pre-released level which maximizes the probability that the reservoir release during flood is below the non-damaging discharge and the end-of-operation storage target can still be achieved. This paper evaluated the operations of Tsengwen Reservoir of southern Taiwan during four typhoons from 2007 to 2012 to illustrate the significant contribution of pre-releases in reducing downstream flood potential.

  8. Controls on Fe(II)-Activated Trace Element Release from Goethite and Hematite

    Energy Technology Data Exchange (ETDEWEB)

    Frierdich, Andrew J.; Catalano, Jeffrey G. (WU)

    2012-03-26

    Electron transfer and atom exchange (ETAE) between aqueous Fe(II) and Fe(III) oxides induces surface growth and dissolution that affects trace element fate and transport. We have recently demonstrated Ni(II) cycling through goethite and hematite (adsorbed Ni incorporates into the mineral structure and preincorporated Ni releases to solution) during Fe(II)-Fe(III) ETAE. However, the chemical parameters affecting net trace element release remain unknown. Here, we examine the chemical controls on Ni(II) and Zn(II) release from Ni- and Zn-substituted goethite and hematite during reaction with Fe(II). Release follows a rate law consistent with surface reaction limited mineral dissolution and suggests that release occurs near sites of Fe(III) reductive dissolution during Fe(II)-Fe(III) ETAE. Metal substituent type affects reactivity; Zn release is more pronounced from hematite than goethite, whereas the opposite trend occurs for Ni. Buildup of Ni or Zn in solution inhibits further release but this resumes upon fluid exchange, suggesting that sustained release is possible under flow conditions. Mineral and aqueous Fe(II) concentrations as well as pH strongly affect sorbed Fe(II) concentrations, which directly control the reaction rates and final metal concentrations. Our results demonstrate that structurally incorporated trace elements are mobilized from iron oxides into fluids without abiotic or microbial net iron reduction. Such release may affect micronutrient availability, contaminant transport, and the distribution of redox-inactive trace elements in natural and engineered systems.

  9. SOLID POLYMERIC MATRIX BASED ON CHITOSAN AND XANTHAN FOR CONTROLLED RELEASE OF FERTILIZERS

    Directory of Open Access Journals (Sweden)

    Mariana A. Melaj

    2012-03-01

    Full Text Available The main purpose of this work was to optimize the preparation conditions of solid polymeric matrix based on Chitosan and Xanthan, to be used in the controlled release of fertilizers. KNO3 was chosen as model agrochemical to be released. Both individual polymers and the Xanthan:Chitosan complex are biocompatible, leaving a residue on the soil which is non-toxic. The influence of different variables on the release pattern was studied: the type of polymer, the pressed conditions of the tablets and the presence of a drug-free polymeric coating. The polymer that presented a more promising release profile was Xanthan. The compression pressure applied to prepare the tablets was a more relevant variable than the compression time, in its effect on the kinetics of release. It was determined that the coating of the polymer matrix with crosslinked chitosan-glutaraldehyde allows getting a larger release time.

  10. 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.

  11. Composite films of poly(vinyl alcohol)-chitosan-bacterial cellulose for drug controlled release.

    Science.gov (United States)

    Pavaloiu, Ramona-Daniela; Stoica-Guzun, Anicuta; Stroescu, Marta; Jinga, Sorin Ion; Dobre, Tanase

    2014-07-01

    Mono and multilayer composite films of poly(vinyl alcohol)-chitosan-bacterial cellulose (PVA/chitosan/BC) have been prepared to achieve controlled release of ibuprofen sodium salt (IbuNa) as model drug. The composite films have been characterized by Fourier transformed infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Surface morphology was investigated by scanning electron microscopy (SEM). Equilibrium swelling was measured in water at two different pH values and in vitro release of IbuNa in pH 1.2 and pH 7.4 media was studied. The release experiments revealed that drug release is pH sensitive. The release kinetics of IbuNa could be described by the Fickian model of diffusion with a good agreement. The IbuNa release rate was decreasing for all the films as the BC concentration was increased in the films composition, the decrease being higher for the multilayer films.

  12. Enzymatic Release and Characterization of Novel Bioactive Peptides from Milk Proteins

    DEFF Research Database (Denmark)

    De Gobba, Cristian

    Milk is considered the most complete food, providing most of the nutrients needed. Milk proteins are not only important for their function as a source of amino acids, but they are also a source of bioactive peptides. These are short amino acid sequences with different activities that have......-inhibitory, antioxidant and antimicrobial peptides) released from milk proteins by mean of enzyme-catalysed hydrolysis. Goat milk fractions (produced using microfiltration membranes) and bovine casein were used as substrates. The goat milk fractions (retentate, permeate and skimmed milk) were hydrolysed with two...... protein hydrolysates made in other studies. Regarding radical scavenging activity, the bovine casein hydrolysates also showed a positive correlation between extent of hydrolysis and activity, although the difference between the unhydrolysed sample and the hydrolysates was less marked. The goat milk...

  13. Enzymatic Release and Characterization of Novel Bioactive Peptides from Milk Proteins

    DEFF Research Database (Denmark)

    De Gobba, Cristian

    -inhibitory, antioxidant and antimicrobial peptides) released from milk proteins by mean of enzyme-catalysed hydrolysis. Goat milk fractions (produced using microfiltration membranes) and bovine casein were used as substrates. The goat milk fractions (retentate, permeate and skimmed milk) were hydrolysed with two...... protein hydrolysates made in other studies. Regarding radical scavenging activity, the bovine casein hydrolysates also showed a positive correlation between extent of hydrolysis and activity, although the difference between the unhydrolysed sample and the hydrolysates was less marked. The goat milk...... hydrolysates, instead, showed a difference between the fractions more than the degree of hydrolysis, the retentate being the most active radical scavenger regardless the degree of hydrolysis and enzyme used. Both hydrolysates are among the most active radical scavenging milk protein hydrolysates known...

  14. Design and in vitro evaluation of controlled release alginate beads of diltiazem hydrochloride

    Institute of Scientific and Technical Information of China (English)

    D.Nagasamy Venkatesh; A.Kalaivani; Kritika D.Kalro; Lalitha Chintha; James Tharani; M.K. Samanta; B.Suresh

    2009-01-01

    Objective:Oral slow and sustained release drug delivery system can release their drug content with a controlled manner,producing a desirable blood serum level,reduction in drug toxicity and improving the patient compli-ance by prolonging dosing intervals.The major drawback of orally administered drug like diltiazem as a calcium channel blocker for the treatment of angina pectoris,arrhythmia and hypertension.Its has higher aqueous solu-bility and shorter elimination half-life.Methods:To overcome these drawbacks associated with diltiazem,an attempt has been made to develop a sustained release dosage form of diltiazem embedded alginate microbeads by ionotropic gelation technique employing various concentrations of polymer and keeping the drug concentra-tion constant.Results:The beads were characterized for its particle size,drug content and in vitro release stud-ies.The results revealed that the surface adhering drug was found to release immediately and a steady state of release was obtained up to 12 h from all the batches.The results indicated there was an inverse relationship be-tween the concentration of alginate and drug release.The drug release was found to follow non-fickian diffusion obeying first order kinetics.Conclusion:The developed alginate microbeads offered a sustained release of dilti-azem.Hence,the formulated microbeads were found to be potential,cost effective,possess satisfactory in vitro release studies.

  15. Whey protein concentrate doped electrospun poly(epsilon-caprolactone) fibers for antibiotic release improvement.

    Science.gov (United States)

    Ahmed, Said Mahmoud; Ahmed, Hanaa; Tian, Chang; Tu, Qin; Guo, Yadan; Wang, Jinyi

    2016-07-01

    Design and fabrication of scaffolds using appropriate biomaterials are a key step for the creation of functionally engineered tissues and their clinical applications. Poly(epsilon-caprolactone) (PCL), a biodegradable and biocompatible material with negligible cytotoxicity, is widely used to fabricate nanofiber scaffolds by electrospinning for the applications of pharmaceutical products and wound dressings. However, the use of PCL as such in tissue engineering is limited due to its poor bioregulatory activity, high hydrophobicity, lack of functional groups and neutral charge. With the attempt to found nanofiber scaffolds with antibacterial activity for skin tissue engineering, in this study, whey protein concentrate (WPC) was used to modify the PCL nanofibers by doping it in the PCL electrospun solution. By adding proteins into PCL nanofibers, the degradability of the fibers may be increased, and this further allows an antibiotic incorporated in the fibers to be efficiently released. The morphology, wettability and degradation of the as-prepared PCL/WPC nanofibers were carefully characterized. The results showed that the PCL/WPC nanofibers possessed good morphology and wettability, as well as high degradation ability to compare with the pristine PCL fibers. Afterwords, tetracycline hydrochloride as a model antibiotic drug was doped in the PCL/WPC nanofibers. In vitro drug release assays demonstrated that PCL/WPC nanofibers had higher antibiotic release capability than the PCL nanofibers. Also, antibacterial activity evaluation against various bacteria showed that the drug-doped PCL/WPC fibers possessed more efficient antibacterial activity than the PCL nanofibers.

  16. Evaluation of BSA protein release from hollow hydroxyapatite microspheres into PEG hydrogel.

    Science.gov (United States)

    Fu, Hailuo; Rahaman, Mohamed N; Brown, Roger F; Day, Delbert E

    2013-05-01

    Implants that simultaneously function as an osteoconductive matrix and as a device for local drug or growth factor delivery could provide an attractive system for bone regeneration. In our previous work, we prepared hollow hydroxyapatite (abbreviated HA) microspheres with a high surface area and mesoporous shell wall and studied the release of a model protein, bovine serum albumin (BSA), from the microspheres into phosphate-buffered saline (PBS). The present work is an extension of our previous work to study the release of BSA from similar HA microspheres into a biocompatible hydrogel, poly(ethylene glycol) (PEG). BSA-loaded HA microspheres were placed in a PEG solution which was rapidly gelled using ultraviolet radiation. The BSA release rate into the PEG hydrogel, measured using a spectrophotometric method, was slower than into PBS, and it was dependent on the initial BSA loading and on the microstructure of the microsphere shell wall. A total of 35-40% of the BSA initially loaded into the microspheres was released into PEG over ~14 days. The results indicate that these hollow HA microspheres have promising potential as an osteoconductive device for local drug or growth factor delivery in bone regeneration and in the treatment of bone diseases.

  17. 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.

  18. Controlled-release fertilizer composition substantially coated with an impermeable layer

    Energy Technology Data Exchange (ETDEWEB)

    Ankeny, Mark

    2016-03-29

    A controlled-release fertilizer composition is provided that is substantially coated with an impermeable layer. The fertilizer composition may further include one or more hollow sections to allow for root penetration and efficient delivery of nutrients.

  19. Self-assembled nanoparticles of glycol chitosan – Ergocalciferol succinate conjugate, for controlled release

    DEFF Research Database (Denmark)

    Quinones, Javier Perez; Gothelf, Kurt Vesterager; Kjems, Jørgen

    2012-01-01

    Glycol chitosan was linked to vitamin D2 hemisuccinate (ergocalciferol hemisuccinate) for controlled release through water-soluble carbodiimide activation. The resulting conjugate formed self-assembled nanoparticles in aqueous solution with particle size of 279 nm and ergocalciferol hemisuccinate...

  20. [Effects of sulfur- and polymer-coated controlled release urea fertilizers on wheat yield and quality and fertilizer nitrogen use efficiency].

    Science.gov (United States)

    Ma, Fu-Liang; Song, Fu-Peng; Gao, Yang; Zou, Peng

    2012-01-01

    A field experiment was conducted to study the effects of sulfur- and polymer-coated controlled release urea fertilizers on wheat yield and its quality, plow layer soil inorganic nitrogen (N) contents, and fertilizer N use efficiency. Compared with traditional urea fertilizer, both sulfur- and polymer-coated controlled release urea fertilizers increased the grain yield by 10.4%-16.5%, and the grain protein and starch contents by 5.8%-18.9% and 0.3%-1.4%, respectively. The controlled release urea fertilizers could maintain the topsoil inorganic N contents to meet the N requirement for the wheat, especially during its late growth stage. In the meantime, the fertilizer N use efficiency was improved by 58.2%-101.2%. Polymer-coated urea produced better wheat yield and higher fertilizer N use efficiency, compared with sulfur-coated controlled release urea.

  1. PREPARATION AND EVALUATION OF HPMC-ALGINATE MUCOADHESIVE MICROCAPSULES OF DICLOFENAC FOR CONTROLLED RELEASE

    Directory of Open Access Journals (Sweden)

    K.P.R. Chowdary

    2011-11-01

    Full Text Available A new, novel promising technology for obtaining controlled release and enhancing the bioavailability is a combination of mucoadhesion principle and microencapsulation to result in mucoadhesive microcapsules. Mucoadhesive microcapsules consist of either entirely of a mucoadhesive polymer or having an outer coating enclosing the drug particles. They facilitate an intimate and prolonged contact with the absorption surface to provide controlled release and enhanced bioavailability of the contained drug over longer period of time to prolong its therapeutic action. The objective of the present work is to prepare HPMC based mucoadhesive microcapsules of diclofenac and to evaluate the microcapsules for mucoadhesiveness and controlled drug release characteristics. Spherical HPMC-alginate mucoadhesive micro- capsules of diclofenac could be prepared by the orifice – ionic gelation method. Microencapsulation efficiency was in the range 98.7 % - 103.5 %. Drug release from the HPMC – alginate microcapsules was slow and spread over a period of 12 h and depended on core: coat ratio and wall thickness of the microcapsules. Drug release mechanism from these microcapsules was by non- Fickian diffusion. Good linear relationships were observed between wall thickness of the microcapsules and release rate [K0 and K1] of the microcapsules. Mucoadhesion testing by in vitro wash-off test indicated good mucoadhesive property of HPMC-alginate microcapsules with a slower wash-off when compared to non-mucoadhesive EVA microcapsules. Thus controlled release mucoadhesive microcapsules of diclofenac could be designed employing HPMC-alginate. HPMC-alginate microcapsules of diclofenac exhibited good mucoadhesion and controlled release characteristics and were found suitable for oral controlled release of diclofenac.

  2. Orchestrated content release from Drosophila glue-protein vesicles by a contractile actomyosin network.

    Science.gov (United States)

    Rousso, Tal; Schejter, Eyal D; Shilo, Ben-Zion

    2016-02-01

    Releasing content from large vesicles measuring several micrometres in diameter poses exceptional challenges to the secretory system. An actomyosin network commonly coats these vesicles, and is thought to provide the necessary force mediating efficient cargo release. Here we describe the spatial and temporal dynamics of the formation of this actomyosin coat around large vesicles and the resulting vesicle collapse, in live Drosophila melanogaster salivary glands. We identify the Formin family protein Diaphanous (Dia) as the main actin nucleator involved in generating this structure, and uncover Rho as an integrator of actin assembly and contractile machinery activation comprising this actomyosin network. High-resolution imaging reveals a unique cage-like organization of myosin II on the actin coat. This myosin arrangement requires branched-actin polymerization, and is critical for exerting a non-isotropic force, mediating efficient vesicle contraction.

  3. Monoclonal antibody targeting chikungunya virus envelope 1 protein inhibits virus release.

    Science.gov (United States)

    Masrinoul, Promsin; Puiprom, Orapim; Tanaka, Atsushi; Kuwahara, Miwa; Chaichana, Panjaporn; Ikuta, Kazuyoshi; Ramasoota, Pongrama; Okabayashi, Tamaki

    2014-09-01

    Chikungunya virus (CHIKV) causes an acute clinical illness characterized by sudden high fever, intense joint pain, and skin rash. Recent outbreaks of chikungunya disease in Africa and Asia are a major public health concern; however, there is currently no effective licensed vaccine or specific treatment. This study reported the development of a mouse monoclonal antibody (MAb), CK47, which recognizes domain III within the viral envelope 1 protein and inhibited the viral release process, thereby preventing the production of progeny virus. The MAb had no effect on virus entry and replication processes. Thus, CK47 may be a useful tool for studying the mechanisms underlying CHIKV release and may show potential as a therapeutic agent.

  4. RIM-binding protein links synaptic homeostasis to the stabilization and replenishment of high release probability vesicles.

    Science.gov (United States)

    Müller, Martin; Genç, Özgür; Davis, Graeme W

    2015-03-04

    Here we define activities of RIM-binding protein (RBP) that are essential for baseline neurotransmission and presynaptic homeostatic plasticity. At baseline, rbp mutants have a ∼10-fold decrease in the apparent Ca(2+) sensitivity of release that we attribute to (1) impaired presynaptic Ca(2+) influx, (2) looser coupling of vesicles to Ca(2+) influx, and (3) limited access to the readily releasable vesicle pool (RRP). During homeostatic plasticity, RBP is necessary for the potentiation of Ca(2+) influx and the expansion of the RRP. Remarkably, rbp mutants also reveal a rate-limiting stage required for the replenishment of high release probability (p) vesicles following vesicle depletion. This rate slows ∼4-fold at baseline and nearly 7-fold during homeostatic signaling in rbp. These effects are independent of altered Ca(2+) influx and RRP size. We propose that RBP stabilizes synaptic efficacy and homeostatic plasticity through coordinated control of presynaptic Ca(2+) influx and the dynamics of a high-p vesicle pool.

  5. Effects of ethanol on aggregation, serotonin release, and amyloid precursor protein processing in rat and human platelets.

    Science.gov (United States)

    Ehrlich, Daniela; Humpel, Christian

    2014-01-01

    It is known that oxidative stress leads to amyloid precursor protein (APP) dysregulation in platelets. Ethanol (EtOH) is a vascular risk factor and induces oxidative stress. The aim of the present study was thus to investigate whether EtOH affects APP processing in rat and human platelets. Platelets were exposed to 50 mM EtOH with and without 2 mM calcium-chloride (CaCl₂) for 20 or 180 minutes at 37°C. Platelet aggregation, serotonin release and APP isoforms 130 and 106/110 kDa were analyzed. As a control, 100 mM H₂O₂ was tested in rat platelets. Our data show that EtOH alone did not affect any of the analyzed parameters, whereas CaCl₂ significantly increased aggregation of rat and human platelets. In addition, CaCl₂ alone enhanced serotonin release in rat platelets. EtOH counteracted CaCl₂-induced aggregation and serotonin release. In the presence of CaCl₂, EtOH reduced the 130 kDa APP isoform in rat and human platelets. In conclusion, this study shows that in the presence of CaCl₂, EtOH affects the platelet function and APP processing in rat and human platelets.

  6. [Research advances on controlled-release mechanisms of nutrients in coated fertilizers].

    Science.gov (United States)

    Zhang, Haijun; Wu, Zhijie; Liang, Wenju; Xie, Hongtu

    2003-12-01

    Using encapsulation techniques to coat easily soluble fertilizers is an important way to improve fertilizer use efficiency while reduce environmental hazards. Based on a wide range of literature collection on coated fertilizer research, the theories, processes, and characters of nutrient controlled-release from coated fertilizer were discussed, and the factors affecting nutrient controlled-release and the mathematical simulations on it were reviewed. The main tendencies related to this research in China were also put forward.

  7. PREPARATION AND EVALUATION OF HPMC-ALGINATE MUCOADHESIVE MICROCAPSULES OF DICLOFENAC FOR CONTROLLED RELEASE

    OpenAIRE

    K.P.R. Chowdary

    2011-01-01

    A new, novel promising technology for obtaining controlled release and enhancing the bioavailability is a combination of mucoadhesion principle and microencapsulation to result in mucoadhesive microcapsules. Mucoadhesive microcapsules consist of either entirely of a mucoadhesive polymer or having an outer coating enclosing the drug particles. They facilitate an intimate and prolonged contact with the absorption surface to provide controlled release and enhanced bioavailability of the containe...

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

    Energy Technology Data Exchange (ETDEWEB)

    Matteini, P; Ratto, F; Rossi, F; Pini, R [Institute of Applied Physics ' Nello Carrara' , National Research Council, via Madonna del Piano 10 50019 Sesto Fiorentino (Italy)

    2014-07-31

    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)

  9. Controlled-Release Oxycodone and Naloxone in the Treatment of Chronic Low Back Pain: A Placebo-Controlled, Randomized Study

    Directory of Open Access Journals (Sweden)

    C Cloutier

    2013-01-01

    Full Text Available BACKGROUND: For Canadian regulatory purposes, an analgesic study was required to complement previously completed, pivotal studies on bowel effects and analgesia associated with controlled-release (CR oxycodone/CR naloxone.

  10. A controlled-release mitochondrial protonophore reverses hypertriglyceridemia, nonalcoholic steatohepatitis, and diabetes in lipodystrophic mice.

    Science.gov (United States)

    Abulizi, Abudukadier; Perry, Rachel J; Camporez, João Paulo G; Jurczak, Michael J; Petersen, Kitt Falk; Aspichueta, Patricia; Shulman, Gerald I

    2017-07-01

    Lipodystrophy is a rare disorder characterized by complete or partial loss of adipose tissue. Patients with lipodystrophy exhibit hypertriglyceridemia, severe insulin resistance, type 2 diabetes, and nonalcoholic steatohepatitis (NASH). Efforts to ameliorate NASH in lipodystrophies with pharmacologic agents have met with limited success. We examined whether a controlled-release mitochondrial protonophore (CRMP) that produces mild liver-targeted mitochondrial uncoupling could decrease hypertriglyceridemia and reverse NASH and diabetes in a mouse model (fatless AZIP/F-1 mice) of severe lipodystrophy and diabetes. After 4 wk of oral CRMP (2 mg/kg body weight per day) or vehicle treatment, mice underwent hyperinsulinemic-euglycemic clamps combined with radiolabeled glucose to assess liver and muscle insulin responsiveness and tissue lipid measurements. CRMP treatment reversed hypertriglyceridemia and insulin resistance in liver and skeletal muscle. Reversal of insulin resistance could be attributed to reductions in diacylglycerol content and reduced PKC-ε and PKC-θ activity in liver and muscle respectively. CRMP treatment also reversed NASH as reflected by reductions in plasma aspartate aminotransferase and alanine aminotransferase concentrations; hepatic steatosis; and hepatic expression of IL-1α, -β, -2, -4, -6, -10, -12, CD69, and caspase 3 and attenuated activation of the IRE-1α branch of the unfolded protein response. Taken together, these results provide proof of concept for the development of liver-targeted mitochondrial uncoupling agents as a potential novel therapy for lipodystrophy-associated hypertriglyceridemia, NASH and diabetes.-Abulizi, A., Perry, R. J., Camporez, J. P. G., Jurczak, M. J., Petersen, K. F., Aspichueta, P., Shulman, G. I. A controlled-release mitochondrial protonophore reverses hypertriglyceridemia, nonalcoholic steatohepatitis, and diabetes in lipodystrophic mice. © FASEB.

  11. Bacteriophage and impurity carryover and total organic carbon release during extended protein A chromatography.

    Science.gov (United States)

    Lute, Scott; Brorson, Kurt

    2009-05-01

    In the biopharmaceutical industry, column chromatography residuals are routinely assessed by the direct measurement of mock eluates. In this study, we evaluated virus and other impurity carryover between protein A cycles and the feasibility of using a total organic carbon (TOC) analyzer to monitor for column impurity leakage as a correlate for actual measured carryover in mock eluates. Commercial process intermediates were used in scaled down studies of two protein A media, ProSep A (Millipore, Bedford, MA, USA) and MabSelect SuRe (GE Healthcare, Uppsala, Sweden). The chromatography system was programmed to run up to 200 normal load/elution cycles with periodic blank cycles to measure protein and phage carryover, and water flush cycles to measure TOC release. Sustained phage carryover was evident in each study. Carryover and TOC release was lowest in the case where cleaning was most stringent (50 mM NaOH/0.5 M Na(2)SO(4) with MabSelect SuRe). The TOC analysis at this time does not appear to be a viable practical means of measuring impurity carryover; direct measurements in mock eluates appears to be more predictive of column performance.

  12. NAIL AS A PROMISING DRUG DELIVERY SYSTEM FOR CONTROLLED RELEASE

    Directory of Open Access Journals (Sweden)

    G. Sai Krishna*, P. Prem Kumar, K. Bala Murugan

    2013-03-01

    Full Text Available ABSTRACT: The effectiveness of topical therapies is limited by minimal drug permeability through the nail plate. Nail permeability is however quite low and limits topical therapy to early/mild disease states such as onychomycosis (fungal infections of the nail. Current research on nail permeation that focuses on altering the nail plate barrier by means of chemical treatments, penetration enhancers as well as physical and mechanical methods is reviewed also the recent research into ungual drug delivery is reviewed, a new method of nail sampling is examined. Topical therapy is worth pursuing however, as local action is required in many nail disorders. Drug transport into the nail plate can be assisted by filing the nail plate before topical application of drug formulations as well as by the use of chemical enhancers. Finally limitations of current ungual drug permeability studies are briefly discussed and the factors, which affect drug uptake and permeation through the nail plate such as solute molecular size, hydrophilicity/hydrophobicity, charge, and the nature of the vehicle, are then discussed, and drug-containing nail lacquers which, like cosmetic varnish, are brushed onto the nail plates to form a film, and from which drug is released and penetrates into the nail are reviewed. The nail plate behaves like a concentrated hydrogel to permeating molecules and diffusion of molecules through the nail plate has been compared to the diffusion of non-electrolytes through polymer gels. Thus, for optimal ungual permeation and uptake, drug molecules must be of small size and be uncharged.

  13. Laser-Triggered Small Interfering RNA Releasing Gold Nanoshells against Heat Shock Protein for Sensitized Photothermal Therapy.

    Science.gov (United States)

    Wang, Zhaohui; Li, Siwen; Zhang, Min; Ma, Yi; Liu, Yuxi; Gao, Weidong; Zhang, Jiaqi; Gu, Yueqing

    2017-02-01

    The resistance of cancer cells to photothermal therapy is closely related to the overexpression of heat shock proteins (HSPs), which are abnormally upregulated when cells are under lethal stresses. Common strategies that use small molecule inhibitors against HSPs to enhance hyperthermia effect lack spatial and temporal control of drug release, leading to unavoidable systemic toxicity. Herein, a versatile photothermal platform is developed which is composed of a hollow gold nanoshell core densely packed with small interfering RNAs against heat shock protein 70 (Hsp70). Upon near infrared light irradiation, the small interfering RNAs can detach from gold surface specifically and escape from endosomes for Hsp70 silencing. Meanwhile, the temperature increases for hyperthermia therapy due to the high photothermal efficiency of the nanoshells. Efficient downregulation of Hsp70 after light activation is achieved in vitro and in vivo. Ultimately, the light-controlled dual functional nanosystem, with the effects of Hsp70 silencing and temperature elevation, results in sensitized photothermal therapy in nude mice model under mild temperature. This strategy smartly combines the localized photothermal therapy with controlled Hsp70 silencing, and has great potential for clinical translation with a simple and easily controlled structure.

  14. Estrogen stimulates release of secreted amyloid precursor protein from primary rat cortical neurons via protein kinase C pathway

    Institute of Scientific and Technical Information of China (English)

    Sun ZHANG; Ying HUANG; Yi-chun ZHU; Tai YAO

    2005-01-01

    Aim: To investigate the mechanism of the action of estrogen, which stimulates the release of secreted amyloid precursor protein α (sAPPα) and decreases the gen eration of amyloid-β protein (Aβ), a dominant component in senile plaques in the brains of Alzheimer's disease patients. Methods: Experiments were carried out inprimary rat cortical neurons, and Western blot was used to detect sAPPα in aculture medium and the total amount of cellular amyloid precursor protein (APP) in neurons. Results: 17β-Estradiol (but not 17α-estradiol) and β-estradiol 6-(Ocarboxymethyl) oxime: BSA increased the secretion of sAPPα and this effect was blocked by protein kinase C (PKC) inhibitor calphostin C, but not by the classical estrogen receptor antagonist ICI 182,780. Meanwhile, 17β-estradiol did not alter the synthesis of cellular APP. Conclusion: The effect of 17β-estradiol on sAPPα secretion is likely mediated through the membrane binding sites, and needs molecular configuration specificity of the ligand. Furthermore, the action of the PKC dependent pathway might be involved in estrogen-induced sAPPα secretion.

  15. Substance P induces tumor necrosis factor-alpha release from human skin via mitogen-activated protein kinase.

    Science.gov (United States)

    Okabe, T; Hide, M; Koro, O; Yamamoto, S

    2000-06-16

    Substance P plays an important role in neurogenic inflammation with granulocyte infiltration. To investigate cytokines involved in the substance P-induced inflammation and the mechanism of cell activation, we studied the release of TNF (tumor necrosis factor)-alpha and histamine from human skin slices in response to substance P and antigen. Substance P induced the release of histamine and TNF-alpha in a dose-dependent manner at concentrations from 0.8 to 100 microM. PD 098059 (2'-amino-3'-methoxyflavone) selectively inhibited the release of TNF-alpha, but not the release of histamine induced by either substance P or antigen. SB 203580 ([4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-++ +imida zole]) slightly inhibited TNF-alpha release induced by antigen, but not that induced by substance P, and slightly enhanced histamine release induced by either stimulation. The release of TNF-alpha in response to either stimulation was inhibited by 1 nM-1 microM dexamethasone, but histamine release was not affected. These results suggest that substance P, in addition to antigen, induced TNF-alpha release from human skin by a mitogen-activated protein (MAP) kinase, predominantly extracellular signaling-regulated protein kinase (ERK)-dependent, and dexamethasone-sensitive pathway, which is separate from that for histamine release from mast cells.

  16. [Effects of slow/controlled release fertilizers on the growth and nutrient use efficiency of pepper].

    Science.gov (United States)

    Tang, Shuan-Hu; Zhang, Fa-Bao; Huang, Xu; Chen, Jian-Sheng; Xu, Pei-Zhi

    2008-05-01

    Pot trails were conducted from 2003 to 2005 to study the effects of slow/controlled release fertilizers on the growth and nutrient use efficiency of pepper. The results indicated that in comparison with conventional splitting fertilization (T1), basal application of polymer-coated controlled release fertilizer (T2) enhanced the single fruit mass and vitamin C concentration, improved the root activity, and increased the fruit yield by 8.4%, but no significant effect was observed on the dissoluble sugar concentration in fruit. NH4MgPO4-coated controlled release fertilizer (T3) increased the dissoluble sugar concentration by 5.67%, but had less effect on single fruit mass and vitamin C concentration. Under the application of T3, the root system had a vigorous growth at early stages but became infirm at later stages, resulting in a lower yield. Comparing with T1, the application of 3 slow release fertilizers increased the dissoluble sugar concentration in fruit, enhanced the root activity, but had less effect on the yield. All test slow/controlled release fertilizers increased the use efficiency of N, P, and K significantly, with an exception for T2 which increased the use efficiency of N and K but decreased that of P. It was demonstrated that an appropriate application of slow/controlled release fertilizers could enhance pepper' s root activity and improve nutrient use efficiency.

  17. 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.

  18. 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.

  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

    2016-10-01

    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. Cellular and subcellular localization of Ras guanyl nucleotide-releasing protein in the rat hippocampus.

    Science.gov (United States)

    Pierret, P; Vallée, A; Mechawar, N; Dower, N A; Stone, J C; Richardson, P M; Dunn, R J

    2001-01-01

    Ras guanyl nucleotide-releasing protein (RasGRP) is a recently discovered Ras guanyl nucleotide exchange factor that is expressed in selected regions of the rodent CNS, with high levels of expression in the hippocampus. Biochemical studies suggest that RasGRP can activate the Ras signal pathway in response to changes in diacylglycerol and possibly calcium. To investigate potential sites for RasGRP signaling, we have determined the cellular and subcellular localization of RasGRP protein in adult rat hippocampus, and have also examined the appearance of RasGRP mRNA and protein during hippocampal development. RasGRP immunoreactivity is predominately localized to those neurons participating in the direct cortico-hippocampo-cortical loop. In both hippocampal and entorhinal neurons, RasGRP protein appeared to be localized to both dendrites and somata, but not to axons. Electron microscopy of hippocampal pyramidal cells confirmed RasGRP immunoreactivity in neuronal cell bodies and dendrites, where it appeared to be associated with microtubules. The localization of RasGRP to dendrites suggests a role for this pathway in the regulation of dendritic function. Examination of developing hippocampal structures indicated that RasGRP mRNA and protein appear synchronously during the first 2 weeks of postnatal development as these neurons become fully mature. This result indicates that the RasGRP signal transduction pathway is not required during early hippocampal development, but is a feature of mature neurons during the later stages of development.

  1. A doxycycline loaded, controlled-release, biodegradable fiber for the treatment of aortic aneurysms.

    Science.gov (United States)

    Yamawaki-Ogata, A; Hashizume, R; Satake, M; Kaneko, H; Mizutani, S; Moritan, T; Ueda, Y; Narita, Y

    2010-12-01

    The pathogenesis of aortic aneurysm (AA) is characterized by degradation of extracellular matrix with increased matrix metalloproteinases (MMPs) and inflammatory reaction. Doxycycline (DOXY) has been reported to control the extension of AA by regulation of MMP. However, systemic administration may cause adverse side effects. In this study, we demonstrated the possibility of local administration of DOXY controlled-release biodegradable fiber (DCRBF) for AA in mice. DCRBF was fabricated by biodegradable polymer (polylactic acid; PLA) mixed with DOXY using an electrospinning technique. DCRBF was cocultured with SMCs, macrophages and aortic tissue, and placed on an abdominal aortic aneurysm which induced apolipoprotein E-deficient mice. We evaluated gene and protein expression of proteases, elastin and inflammatory markers. In the presence of DCRBF, MMP-12 was significantly decreased, TGF-β1 and Lox were significantly increased in SMC gene expression, MMP-9 and -12 significantly decreased gene expression of macrophages. The DCRBF preserved elastin content and decreased MMP-2 and -9 in aortic tissue. In addition, IGF-1 and TIMP-1 were significantly increased and IL-6 and TNF-α were significantly decreased with DCRBF in vivo. In conclusion, our results suggested that local administration of DCRBF may become a promising alternative therapeutic strategy for AA. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Design and evaluation of controlled onset extended release multiparticulate systems for chronotherapeutic delivery of ketoprofen

    Directory of Open Access Journals (Sweden)

    Shivakumar H

    2006-01-01

    Full Text Available An oral controlled onset extended release dosage form intended to approximate the chronobiology of rheumatoid arthritis is proposed for site-specific release to the colon. The multiparticulate system consisting of drug-loaded cellulose acetate cores encapsulated within Eudragit S-100 microcapsules was designed for chronotherapeutic delivery of ketoprofen. Drug-loaded cellulose acetate cores were prepared by emulsion solvent evaporation technique in an oily phase at different drug:polymer ratios (1:1, 2:1 and 4:1. These cores were successfully microencapsulated with Eudragit S-100 following the same technique at the core:coat ratio of 1:5. Scanning electron microscopy (SEM revealed that the cellulose acetate cores were discrete, uniform and spherical with a porous and rough surface, whereas the Eudragit microcapsules were discrete and spherical with a smooth and dense surface. In vitro drug release studies of the Eudragit microcapsules were performed in different pH conditions following pH-progression method for a period of 16 h. The release studies indicated that the microcapsules posses both pH-sensitive and controlled-release properties, showing limited drug release below pH 7.0 (6.40 to 8.94%, following which the cellulose acetate cores effectively controlled the drug release for a period of 11 h in pH 7.5. The differential scanning calorimetric and powder X-ray diffraction studies demonstrated that ketoprofen was present in dissolved state in the cellulose acetate polymeric matrix, which could explain the controlled drug release from the cores. The release of ketoprofen from Eudragit microcapsules in pH 7.5 depended on the cellulose acetate levels and was characterized by Higuchi′s diffusion model.

  3. Investigation of protein distribution in solid lipid particles and its impact on protein release using coherent anti-Stokes Raman scattering microscopy

    DEFF Research Database (Denmark)

    Christophersen, Philip C.; Birch, Ditlev; Saarinen, Jukka

    2015-01-01

    The aim of this study was to gain new insights into protein distribution in solid lipid microparticles (SLMs) and subsequent release mechanisms using a novel label-free chemical imaging method, coherent anti-Stokes Raman scattering (CARS) microscopy. Lysozyme-loaded SLMs were prepared using...... different lipids with lysozyme incorporated either as an aqueous solution or as a solid powder. Lysozyme distribution in SLMs was investigated using CARS microscopy with supportive structural analysis using electron microscopy. The release of lysozyme from SLMs was investigated in a medium simulating......-destructive method for elucidating the distribution of lysozyme in SLMs. The interpretation of protein distribution and release during lipolysis enabled elucidation of protein release mechanisms. In future, CARS microscopy analysis could facilitate development of a wide range of protein-lipid matrices with tailor...

  4. Controlled-Release Personal Use Arthropod Repellent Formulation

    Science.gov (United States)

    1985-09-25

    deodorant , or other cosmetic enhancers, and rinsed with 70% ethanol. For each subject control site, (5 cm in diameter), anG two test sites, 6 x 16.7 cm...Camouflage 0-1 c) Polyurethane Rifle Stocks 51 Metals S-1 a) Aluminum General Equipeent 6) Natural Products -- I a) Leather Boots 7) Textiles T-1 a...The area was slightly tacky to touch and a definite loss of gloss was noted. * e. metals Aluminum was not visibly affected by all three solutions. f

  5. Pore size is a critical parameter for obtaining sustained protein release from electrochemically synthesized mesoporous silicon microparticles

    Directory of Open Access Journals (Sweden)

    Ester L. Pastor

    2015-10-01

    Full Text Available Mesoporous silicon has become a material of high interest for drug delivery due to its outstanding internal surface area and inherent biodegradability. We have previously reported the preparation of mesoporous silicon microparticles (MS-MPs synthesized by an advantageous electrochemical method, and showed that due to their inner structure they can adsorb proteins in amounts exceeding the mass of the carrier itself. Protein release from these MS-MPs showed low burst effect and fast delivery kinetics with complete release in a few hours. In this work, we explored if tailoring the size of the inner pores of the particles would retard the protein release process. To address this hypothesis, three new MS-MPs prototypes were prepared by electrochemical synthesis, and the resulting carriers were characterized for morphology, particle size, and pore structure. All MS-MP prototypes had 90 µm mean particle size, but depending on the current density applied for synthesis, pore size changed between 5 and 13 nm. The model protein α-chymotrypsinogen was loaded into MS-MPs by adsorption and solvent evaporation. In the subsequent release experiments, no burst release of the protein was detected for any prototype. However, prototypes with larger pores (>10 nm reached 100% release in 24–48 h, whereas prototypes with small mesopores (<6 nm still retained most of their cargo after 96 h. MS-MPs with ∼6 nm pores were loaded with the osteogenic factor BMP7, and sustained release of this protein for up to two weeks was achieved. In conclusion, our results confirm that tailoring pore size can modify protein release from MS-MPs, and that prototypes with potential therapeutic utility for regional delivery of osteogenic factors can be prepared by convenient techniques.

  6. Controlling pH in shake flasks using polymer-based controlled-release discs with pre-determined release kinetics

    Directory of Open Access Journals (Sweden)

    Klee Doris

    2011-03-01

    Full Text Available Abstract Background There are significant differences in the culture conditions between small-scale screenings and large-scale fermentation processes. Production processes are usually conducted in fed-batch cultivation mode with active pH-monitoring and control. In contrast, screening experiments in shake flasks are usually conducted in batch mode without active pH-control, but with high buffer concentrations to prevent excessive pH-drifts. These differences make it difficult to compare results from screening experiments and laboratory and technical scale cultivations and, thus, complicate rational process development. In particular, the pH-value plays an important role in fermentation processes due to the narrow physiological or optimal pH-range of microorganisms. To reduce the differences between the scales and to establish a pH-control in shake flasks, a newly developed easy to use polymer-based controlled-release system is presented in this paper. This system consists of bio-compatible silicone discs embedding the alkaline reagent Na2CO3. Since the sodium carbonate is gradually released from the discs in pre-determined kinetics, it will ultimately compensate the decrease in pH caused by the biological activity of microorganisms. Results The controlled-release discs presented here were successfully used to cultivate E. coli K12 and E. coli BL21 pRSET eYFP-IL6 in mineral media with glucose and glycerol as carbon (C sources, respectively. With glucose as the C-source it was possible to reduce the required buffer concentration in shake flask cultures by 50%. Moreover, with glycerol as the C-source, no buffer was needed at all. Conclusions These novel polymer-based controlled-release discs allowed buffer concentrations in shake flask media to be substantially reduced or omitted, while the pH remains in the physiological range of the microorganisms during the whole cultivation time. Therefore, the controlled-release discs allow a better control of

  7. Controlled poorly soluble drug release from solid self-microemulsifying formulations with high viscosity hydroxypropylmethylcellulose.

    Science.gov (United States)

    Yi, Tao; Wan, Jiangling; Xu, Huibi; Yang, Xiangliang

    2008-08-07

    The objective of this work was the development of a controlled release system based on self-microemulsifying mixture aimed for oral delivery of poorly water-soluble drugs. HPMC-based particle formulations were prepared by spray drying containing a model drug (nimodipine) of low water solubility and hydroxypropylmethylcellulose (HPMC) of high viscosity. One type of formulations contained nimodipine mixed with HPMC and the other type of formulations contained HPMC and nimodipine dissolved in a self-microemulsifying system (SMES) consisting of ethyl oleate, Cremophor RH 40 and Labrasol. Based on investigation by transmission electron microscopy (TEM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray powder diffraction, differences were found in the particle structure between both types of formulations. In vitro release was performed and characterized by the power law. Nimodipine release from both types of formulations showed a controlled release profile and the two power law parameters, n and K, correlated to the viscosity of HPMC. The parameters were also influenced by the presence of SMES. For the controlled release solid SMES, oil droplets containing dissolved nimodipine diffused out of HPMC matrices following exposure to aqueous media. Thus, it is possible to control the in vitro release of poorly soluble drugs from solid oral dosage forms containing SMES.

  8. Controlled release properties of zein-fatty acid blend films for multiple bioactive compounds.

    Science.gov (United States)

    Arcan, Iskender; Yemenicioğlu, Ahmet

    2014-08-13

    To develop edible films having controlled release properties for multiple bioactive compounds, hydrophobicity and morphology of zein films were modified by blending zein with oleic (C18:1)Δ⁹, linoleic (C18:2)Δ(9,12), or lauric (C₁₂) acids in the presence of lecithin. The blend zein films showed 2-8.5- and 1.6-2.9-fold lower initial release rates for the model active compounds, lysozyme (LYS) and (+)-catechin (CAT), than the zein control films, respectively. The change of fatty acid chain length affected both CAT and LYS release rates while the change of fatty acid double bond number affected only the CAT release rate. The film morphologies suggested that the blend films owe their controlled release properties mainly to the microspheres formed within their matrix and encapsulation of active compounds. The blend films showed antilisterial activity and antioxidant activity up to 81 μmol Trolox/cm². The controlled release of multiple bioactive compounds from a single film showed the possibility of combining application of active and bioactive packaging technologies and improving not only safety and quality but also health benefits of packed food.

  9. Melatonin attenuates hypochlorous acid-mediated heme destruction, free iron release, and protein aggregation in hemoglobin.

    Science.gov (United States)

    Maitra, Dhiman; Abdulhamid, Ibrahim; Diamond, Michael P; Saed, Ghassan M; Abu-Soud, Husam M

    2012-09-01

    In inflammatory diseases, where hypochlorous acid (HOCl) is elevated, iron homeostasis is disturbed, resulting in accumulation of free iron. Free iron is toxic by virtue of its ability to generate free radicals through the Fenton reaction. HOCl is generated by myeloperoxidase, (MPO) using chloride and hydrogen peroxide as substrates. Recent studies demonstrate that HOCl binds to the heme moiety of hemoglobin (Hb), which generates a transient ferric species whose formation and decay kinetics indicate it participates in protein aggregation, heme destruction, and free iron release. Here, we show that melatonin prevents HOCl-mediated Hb heme destruction and protein aggregation, using a combination of UV-vis spectrophotometry, ferrozine colorimetric assay, and in-gel heme staining. We also show that melatonin treatment prevents HOCl-mediated loss of red blood cell (RBC) viability, indicating biologic relevance of this finding. The mechanism by which melatonin prevents HOCl-mediated Hb heme destruction is by direct scavenging of HOCl and/or through the destabilization of the higher Hb oxidative states intermediates, ferryl porphyrin radical cation Hb-Fe(IV)=O(+π•) and Hb-Fe(IV)=O, which are formed through the reaction of HOCl with Hb. Our work establishes a direct mechanistic link between melatonin and its protective effect in chronic inflammatory diseases. Collectively, in addition to acting as an antioxidant and as a MPO inhibitor, melatonin can also exert its protective effect by inhibiting HOCl-mediated heme destruction of hemoproteins and subsequent free iron release.

  10. E-Control: First Public Release of Remote Control Software for VLBI Telescopes

    Science.gov (United States)

    Neidhardt, Alexander; Ettl, Martin; Rottmann, Helge; Ploetz, Christian; Muehlbauer, Matthias; Hase, Hayo; Alef, Walter; Sobarzo, Sergio; Herrera, Cristian; Himwich, Ed

    2010-01-01

    Automating and remotely controlling observations are important for future operations in a Global Geodetic Observing System (GGOS). At the Geodetic Observatory Wettzell, in cooperation with the Max-Planck-Institute for Radio Astronomy in Bonn, a software extension to the existing NASA Field System has been developed for remote control. It uses the principle of a remotely accessible, autonomous process cell as a server extension for the Field System. The communication is realized for low transfer rates using Remote Procedure Calls (RPC). It uses generative programming with the interface software generator idl2rpc.pl developed at Wettzell. The user interacts with this system over a modern graphical user interface created with wxWidgets. For security reasons the communication is automatically tunneled through a Secure Shell (SSH) session to the telescope. There are already successful test observations with the telescopes at O Higgins, Concepcion, and Wettzell. At Wettzell the software is already used routinely for weekend observations. Therefore the first public release of the software is now available, which will also be useful for other telescopes.

  11. 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.

  12. Genetic noise control via protein oligomerization

    Directory of Open Access Journals (Sweden)

    Almaas Eivind

    2008-11-01

    Full Text Available Abstract Background Gene expression in a cell entails random reaction events occurring over disparate time scales. Thus, molecular noise that often results in phenotypic and population-dynamic consequences sets a fundamental limit to biochemical signaling. While there have been numerous studies correlating the architecture of cellular reaction networks with noise tolerance, only a limited effort has been made to understand the dynamic role of protein-protein interactions. Results We have developed a fully stochastic model for the positive feedback control of a single gene, as well as a pair of genes (toggle switch, integrating quantitative results from previous in vivo and in vitro studies. In particular, we explicitly account for the fast binding-unbinding kinetics among proteins, RNA polymerases, and the promoter/operator sequences of DNA. We find that the overall noise-level is reduced and the frequency content of the noise is dramatically shifted to the physiologically irrelevant high-frequency regime in the presence of protein dimerization. This is independent of the choice of monomer or dimer as transcription factor and persists throughout the multiple model topologies considered. For the toggle switch, we additionally find that the presence of a protein dimer, either homodimer or heterodimer, may significantly reduce its random switching rate. Hence, the dimer promotes the robust function of bistable switches by preventing the uninduced (induced state from randomly being induced (uninduced. Conclusion The specific binding between regulatory proteins provides a buffer that may prevent the propagation of fluctuations in genetic activity. The capacity of the buffer is a non-monotonic function of association-dissociation rates. Since the protein oligomerization per se does not require extra protein components to be expressed, it provides a basis for the rapid control of intrinsic or extrinsic noise. The stabilization of regulatory circuits

  13. Plasmon excitation of supported gold nanoparticles can control molecular release from supramolecular systems.

    Science.gov (United States)

    Marquez, Daniela T; Carrillo, Adela I; Scaiano, Juan C

    2013-08-20

    Hybrid mesoporous silica materials containing gold nanoparticles (AuNPs) have been investigated as potential molecular delivery systems. The photophysical properties of AuNPs, particularly their plasmon band transitions, have been used to control the rate of the release of naproxen from the pores of mesoporous silica matrices. Two different approaches were employed to incorporate AuNPs into the silica network: that is, grafting (using 3-aminopropyltriethoxisilane) and direct absorption. In this research, the anti-inflamatory drug naproxen serves as a test molecule, showing how localized plasmon heating could be used to modify diffusion kinetics within mesoporous materials. Beyond naproxen release, the methodology developed could be employed to release other drugs, sensors, or active molecules, not just in medicine, but in many other fields where nanotechnology is leading to many innovative applications. The hybrid materials developed show a new simple system to efficiently control the release of active cargo from mesoporous silica matrices.

  14. 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.

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

    Science.gov (United States)

    Gao, Xiaorui; Lei, Lixu; O'Hare, Dermot; Xie, Juan; Gao, Pengran; Chang, Tao

    2013-07-01

    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 CO32- solutions imply that Mg3Al-VC LDH is a better controlled release system than Mg3Fe-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 CO32- solution.

  16. Smart electrospun nanofibers for controlled drug release: recent advances and new perspectives.

    Science.gov (United States)

    Weng, Lin; Xie, Jingwei

    2015-01-01

    In biological systems, chemical molecules or ions often release upon certain conditions, at a specific location, and over a desired period of time. Electrospun nanofibers that undergo alterations in the physicochemical characteristics corresponding to environmental changes have gained considerable interest for various applications. Inspired by biological systems, therapeutic molecules have been integrated with these smart electrospun nanofibers, presenting activation-modulated or feedback-regulated control of drug release. Compared to other materials like smart hydrogels, environment-responsive nanofiber-based drug delivery systems are relatively new but possess incomparable advantages due to their greater permeability, which allows shorter response time and more precise control over the release rate. In this article, we review the mechanisms of various environmental parameters functioning as stimuli to tailor the release rates of smart electrospun nanofibers. We also illustrate several typical examples in specific applications. We conclude this article with a discussion on perspectives and future possibilities in this field.

  17. Formulation optimization of hydrodynamically balanced oral controlled release bioadhesive tablets of tramadol hydrochloride.

    Science.gov (United States)

    Singh, Bhupinder; Rani, Ashu; Babita; Ahuja, Naveen; Kapil, Rishi

    2010-01-01

    The directly compressible floating-bioadhesive tablets of tramadol were formulated using varying amounts Carbopol 971P (CP) and hydroxy-propylmethyl cellulose (HPMC), along with other requisite excipients. In vitro drug release profile, floatational characteristics and ex vivo bioadhesive strength using texture analyzer were determined, and systematically optimized using a 3(2) central composite design (CCD). The studies indicated successful formulation of gastroretentive compressed matrices with excellent controlled release, mucoadhesion and hydrodynamic balance. Comparison of the dissolution profiles of the optimized formulation, with optimal composition of CP:HPMC :: 80.0:125.0, with that of the marketed controlled release formulation other indicated analogy of drug release performance with each other. Validation of optimization study using eight confirmatory experimental runs indicated very high degree of prognostic ability of CCD with mean  SEM of â0.06%  0.37. Further, the study successfully unravels the effect of the polymers on the selected response variables.

  18. FABRICATION AND EVALUATION OF GLIPIZIDE ABELMOSCHUS ESCULENTUS FRUIT MUCILAGE POVIDONE CONTROLLED RELEASE MATRIX TABLETS

    Directory of Open Access Journals (Sweden)

    Hindustan Abdul Ahad

    2011-02-01

    Full Text Available The present investigation was aimed to prepare matrix type controlled release tablets of Glipizide with Abelmoschus esculentus fruit mucilage and Povidone. The polymers were studied for its functionality as a matrix forming property to sustain the Glipizide release from the dosage form. Physicochemical properties of dried powdered mucilage of Abelmoschus esculentus fruit mucilage and Povidone blend were studied. Various formulations of Glipizide Abelmoschus esculentus fruit mucilage and Povidone were prepared. The prepared tablets were found to have better pharmacopoeial parameters with low standard deviation values. The swelling behavior and release rate characteristics were studied. The in-vitro dissolution study proved that the dried Abelmoschus esculentus fruit mucilage and Povidone in combination can be used as a matrix forming polymers for making controlled release matrix tablets.

  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. Photo-controlled release of fipronil from a coumarin triggered precursor.

    Science.gov (United States)

    Gao, Zhenhong; Yuan, Pengtao; Wang, Donghui; Xu, Zhiping; Li, Zhong; Shao, Xusheng

    2017-06-01

    Developing efficient controlled release system of insecticide can facilitate the better use of insecticide. We described here a first example of photo-controlled release of an insecticide by linking fipronil with photoresponsive coumarin covalently. The generated coumarin-fipronil (CF) precursor could undergo cleavage to release free fipronil in the presence of blue light (420nm) or sunlight. Photophysical studies of CF showed that it exhibited strong fluorescence properties. The CF had no obvious activity against mosquito larvae under dark, but it can be activated by light inside the mosquito larvae. The released Fip from CF by blue light irradiation in vitro retained its activity to armyworm (Mythimna separate) with LC50 value of 24.64μmolL(-1). This photocaged molecule provided an alternative delivery method for fipronil. Copyright © 2017. Published by Elsevier Ltd.

  1. 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.

  2. Rosin and rosin derivatives as hydrophobic matrix materials for controlled release of drugs.

    Science.gov (United States)

    Pathak, Y V; Dorle, A K

    1990-09-01

    The evaluation of rosin, a rosin hard paraffin adduct, and four rosin esters as hydrophobic matrix materials for the controlled release of drugs is reported, using aspirin as a drug model. Aspirin matrix tablets were prepared using a wet granulation (nonaqueous) method, and were evaluated for various pharmaceutical parameters. Dissolution studies in pH 7.2 phosphate buffer showed that all formulations had hardness greater than 6 kg/cm2 and disintegration time greater than 150 min. Release of aspirin from the formulations obeyed a diffusion controlled first order kinetic and linear to the square root of time function. Two of the resin ester formulations had a T80% of more than 4 hr. The results suggest that these esters may find application in the development of sustained release formulations for the local treatment of dental diseases, or--as tablet matrices suitably coated with acid resistant material--in the development of oral sustained release drug delivery systems.

  3. The Preparation of Salbutamol Sulfate Controlled Release TabletsCoated with Cellulose Acetate Aqueous Dispersion

    Institute of Scientific and Technical Information of China (English)

    ZhangFengyu; WuTao; PanWeisan; ChenJimin; ZhangRuhua

    2001-01-01

    In this study, emulsion-solvent evaporation method was applied to prepare the cellulose acetate(CA) aqueous dispersion. Upon the analyzing of the character of the aqueous dispersion, a controlled releaseformulation of salbutamol sulfate coated with cellulose acetate aqueous dispersion was prepared through orthogonalexperiment design. The factors that control the drug release character of the tablets were investigated. The drugrelease mechanism of the formulation was also studied. The experimental results indicated that CA aqueousdispersion had excellent film-forming ability under the effect of plasticizer. The drug release profile of the controlledrelease tablets coated with CA aqueous dispersion exhibited zero-order release character and the drug release rate wasmodulated by the osmotic pressure of the dissolution medium.

  4. Preparation of acetylsalicylic acid-acylated chitosan as a novel polymeric drug for drug controlled release.

    Science.gov (United States)

    Liu, Changkun; Wu, Yiguang; Zhao, Liyan; Huang, Xinzheng

    2015-01-01

    The acetylsalicylic acid-acylated chitosan (ASACTS) with high degree of substitution (DS) was successfully synthesized, and characterized with FTIR, (1)H NMR and elemental analysis methods. The optimum synthesis conditions were obtained which gave the highest DS (about 60%) for ASACTS. Its drug release experiments were carried out in simulated gastric and intestine fluids. The results show that the drugs in the form of acetylsalicylic acid (ASA) and salicylic acid (SA) were released in a controlled manner from ASACTS only in simulated gastric fluid. The release profile can be best fitted with logistic and Weibull model. The research results reveal that ASACTS can be a potential polymeric drug for the controlled release of ASA and SA in the targeted gastric environment.

  5. Polysaccharide-based nanocomplexes for co-encapsulation and controlled release of 5-Fluorouracil and Temozolomide.

    Science.gov (United States)

    Di Martino, Antonio; Pavelkova, Alena; Maciulyte, Sandra; Budriene, Saulute; Sedlarik, Vladimir

    2016-09-20

    Polysaccharide-based nanocomplexes, intended for simultaneous encapsulation and controlled release of 5-Fluorouracil (5-FU) and Temozolomide (TMZ) were developed via the complexation method using chitosan, alginic and polygalacturonic acid. Investigation focused on the influence of polysaccharides on the properties of the system and amelioration of the stability of the drugs, in particular TMZ. The dimensions of particles and their ζ-potential were found to range between 100 and 200nm and -25 to +40mV, respectively. Encapsulation efficiency varied from 16% to over 70%, depending on the given system. The influence of pH on the release and co-release of TMZ and 5-FU was evaluated under different pH conditions. The stability of the loaded drug, in particular TMZ, after release was evaluated and confirmed by LC-MS analysis. Results suggested that the amount of loaded drug(s) and the release rate is connected with the weight ratio of polysaccharides and the pH of the media. One-way ANOVA analysis on the obtained data revealed no interference between the drugs during the encapsulation and release process, and in particular no hydrolysis of TMZ occurred suggesting that CS-ALG and CS-PGA would represent interesting carriers for multi-drug controlled release and drugs protection.

  6. A Study on the Control of Pseudoephedrine Hydrochloride Release from Hydroxypropylmethylcellulose Matrices

    Energy Technology Data Exchange (ETDEWEB)

    Cho, H.; Chung, Y.S. [Department of Chemistry, Chungbuk National University, Cheongju (Korea); Bang, M.S. [Department of Industrial Chemistry, Chonan National Technical College, Chonnam (Korea)

    1999-04-01

    Hydroxypropylmethylcelluloses (HPMC) are cellulose ethers which may be used as the basis for hydrophilic matrices for controlled release oral delivery and offer the advantages of being non-toxic and relatively inexpensive. In this work, we designed new drug release system using HPMC as matrix, manufactured by direct compression technology and have investigated the effects of the controlling factors on drug release from a swellable hydrophillic delivery system. It was found that the release rate of the drug decreased with increasing the polymer molecular weight and the polymer content in tablets, and was independent of compaction pressure and pH of dissolution fluids. Especially, the ability of the anionic surfactant, sodium laurylsulfate, to retard the release of pseudoephedrine hydrochloride from HPMC was characterised. With increasing the concentration of the sodium laurylsulfate within the matrix, drug release rate decreased. It is believed that, provided the pseudoephedrine hydrochloride and the sodium laurylsulfate are oppositely charged, they will bind together in situ within the HPMC matrix, leading to reduced drug release rates. 23 refs., 7 figs.

  7. Mucoadhesive Microcapsules of Indomethacin: Evaluation for Controlled Release and Ulcerogenic Activity

    Directory of Open Access Journals (Sweden)

    K.P.R. Chowdary

    2009-07-01

    Full Text Available Mucoadhesive microcapsules of indomethacin were prepared by an emulsification-ionic gelation process employing sodium carboxy methylcellulose, methylcellulose, Carbopol and hydroxy propyl methyl cellulose along with alginate and the microcapsules were evaluated for release kinetics and ulcerogenic activity. The resulting microcapsules were discrete, free flowing, multinucleate, monolithic and spherical. Microencapsulation efficiency was 41-70 % and relatively high with alginate-sodium carboxymethylcellulose. Indomethacin release from these mucoadhesive microcapsules was found to be slow and extended over longer periods of time and depended on the composition of coat and size of the microcapsules. Drug release was diffusion controlled and followed first order kinetics. Alginate-methyl cellulose and alginate-sodium carboxymethylcellulose microcapsules were found suitable for oral controlled release. The microcapsules exhibited good mucoadhesive property in the in vitro wash-off test. Release from some microcapsules fulfilled the official (USP 23 drug release test-2 requirement of indomethacin extended release capsules. A 62-80 % reduction in ulcerogenic activity was observed with these microcapsules when compared to pure drug indomethacin.

  8. 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.

  9. Thermal stability, storage and release of proteins with tailored fit in silica

    Science.gov (United States)

    Chen, Yun-Chu; Smith, Tristan; Hicks, Robert H.; Doekhie, Aswin; Koumanov, Francoise; Wells, Stephen A.; Edler, Karen J.; van den Elsen, Jean; Holman, Geoffrey D.; Marchbank, Kevin J.; Sartbaeva, Asel

    2017-04-01

    Biological substances based on proteins, including vaccines, antibodies, and enzymes, typically degrade at room temperature over time due to denaturation, as proteins unfold with loss of secondary and tertiary structure. Their storage and distribution therefore relies on a “cold chain” of continuous refrigeration; this is costly and not always effective, as any break in the chain leads to rapid loss of effectiveness and potency. Efforts have been made to make vaccines thermally stable using treatments including freeze-drying (lyophilisation), biomineralisation, and encapsulation in sugar glass and organic polymers. Here for the first time we show that proteins can be enclosed in a deposited silica “cage”, rendering them stable against denaturing thermal treatment and long-term ambient-temperature storage, and subsequently released into solution with their structure and function intact. This “ensilication” method produces a storable solid protein-loaded material without the need for desiccation or freeze-drying. Ensilication offers the prospect of a solution to the “cold chain” problem for biological materials, in particular for vaccines.

  10. PECTIN MICROGELS CONTAINING SYNTHETIC POLYMERS BASED ON NANOCAPSULES FOR THE CONTROLLED RELEASE OF INDOMETHACIN

    Directory of Open Access Journals (Sweden)

    Mihaela HOLBAN

    2015-12-01

    Full Text Available Nanocapsule-based Eudragit RS100 and Eudragit E100 containing indomethacin have been prepared. The nanosuspensions have been included into pectin microgels of different polysaccharide concentrations, 28-61 µm-ranged polymer microgels with size and size polydispersity highly depending on the pectin amount being thus obtained. Study of the drug release revealed that indomethacin was released at a slower and more controlled rate from the microgels containing nanocapsules than from the empty pectin microgels. Also, the rate of released indomethacin increased with the augmentation of pectin amount into the microgels.

  11. Controlled oxygen release from pyridone endoperoxides promotes cell survival under anoxic conditions

    OpenAIRE

    Benz, Sebastian; Noetzli, Sarah; Siegel, Jay; Eberli, Daniel; Jessen, Henning Jacob

    2013-01-01

    In tissue engineering, survival of larger constructs remains challenging due to limited supply with oxygen caused by a lack of early vascularization. Controlled release of oxygen from small organic molecules represents a possible strategy to prevent cell death under anoxic conditions. A comprehensive study of methylated pyridone-derived endoperoxides has led to the development of water-soluble molecules that undergo retro Diels-Alder reactions in aqueous environment releasing oxygen in high y...

  12. Design and evaluation of controlled release mucoadhesive microspheres of amoxicillin for anti Helicobacter pylori therapy

    OpenAIRE

    N Venkateswaramurthy; Sambathkumar, R.; Perumal, P.

    2011-01-01

    The aim of this study was to develop controlled release mucoadhesive microspheres of amoxicillin trihydrate for the treatment of peptic ulcer disease caused by Helicobacter pylori (H. pylori). Microspheres were prepared by solvent evaporation technique using carbopol 974P, hydroxypropyl methyl cellulose K4M (HPMC K4M) and Eudragit RS 100. The prepared microspheres were subjected to evaluation for particle size, incorporation efficiency, in vitro mucoadhesion and in vitro drug release characte...

  13. Controlled release behaviour and antibacterial effects of antibiotic-loaded titania nanotubes.

    Science.gov (United States)

    Feng, Wenchao; Geng, Zhen; Li, Zhaoyang; Cui, Zhenduo; Zhu, Shengli; Liang, Yanqin; Liu, Yunde; Wang, Renfeng; Yang, Xianjin

    2016-05-01

    Bacterial infections have been identified as the main cause of orthopaedic implant failure. Owing to their high antibiotic delivery efficiency, titania nanotubes loaded with antibiotics constitute one of the most promising strategies for suppressing bacterial infections. However, it is difficult to control the drug-release behaviour of such nanotubes. Although sealing the nanotubes with a polymer solution provides sustained release effects to a certain extent, it inevitably influences their initial antibacterial activity. This study reports on the controlled release of gentamicin sulphate (GS) from titania nanotube surfaces whereby their initial antibacterial activity remains unaffected. Titania nanotubes were fabricated via electrochemical anodization and loaded with GS through physical adsorption. Experimental results showed that this loading method is feasible and efficient. The GS-loaded titania nanotubes were further covered by a thin film comprising a mixture of GS and chitosan (GSCH). The release kinetics confirmed that the drug release could be controlled by this thin film. Moreover, such a film was shown to not only inhibit initial bacterial adherence owing to its strong antibacterial properties but also enhance cell viability. Thus, GS-loaded titania nanotubes coated with GSCH have considerable potential as biomaterials for preventing initial release and peri-implant infection in the field of orthopaedics.

  14. Controlled release by novel lysostaphin-loaded hydroxyapatite/chitosan composites.

    Science.gov (United States)

    Wang, Jin-Cheng; Xue, Bai; Ge, Kui-Kui; Wang, Yi-Han; Li, Guo-Dong; Huang, Qing-Shan

    2014-09-01

    Lysostaphin is highly effective on eliminating methicillin resistant Staphylococcus aureus (MRSA). In order to achieve controlled release of lysostaphin, a biocompatible drug carrier is needed. Hydroxyapatite/chitosan (HA/CS) composites were chosen to carry lysostaphin and sample composites with different weight ratios of HA to CS, including 80/20, 70/30, 60/40, and 40/60, were prepared. Multiple analyses were performed to determine the structural and physicochemical properties of the composites, including scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. We immersed HA/CS composites loaded with 1 wt% lysostaphin to test in vitro release activity and cultured MC3T3-E1 cells to carry out biocompatibility test. The result of the release behavior of the composites revealed that the controlled release of lysostaphin from 60/40 HA/CS composites was the highest release rate of (87.4 ± 2.8)%, which lasted for 120 hours. In biocompatibility testing, MC3T3-E1 cells were able to proliferate on the surface of these composites, and the extract liquid from the composites could increase the growth of the cells. These results demonstrate the controlled release of lysostaphin from HA/CS composites and their biocompatibility, suggesting the potential application of these composites to bone injury and infection applications.

  15. Improving the controlled release of water-insoluble emodin from amino-functionalized mesoporous silica

    Energy Technology Data Exchange (ETDEWEB)

    Xu Yunqiang; Wang Chunfeng [Shandong Provincial Key Laboratory of Fine Chemicals, School of Chemistry, Shandong Polytechnic University, Jinan 250353, Shandong (China); Zhou Guowei, E-mail: guoweizhou@hotmail.com [Shandong Provincial Key Laboratory of Fine Chemicals, School of Chemistry, Shandong Polytechnic University, Jinan 250353, Shandong (China); Wu Yue; Chen Jing [Shandong Provincial Key Laboratory of Fine Chemicals, School of Chemistry, Shandong Polytechnic University, Jinan 250353, Shandong (China)

    2012-06-15

    Several types of amino-functionalized mesoporous silica, including F5-SBA-15, F10-SBA-15, and F15-SBA-15 were prepared through co-condensation of tetraethoxysilane (TEOS) and (3-aminopropyl)triethoxysilane (APTES) in varying molar ratios (5 mol%, 10 mol%, and 15 mol%) via a hydrothermal process. The materials obtained were characterized by means of small-angle X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, N{sub 2} adsorption-desorption, Fourier transformed infrared spectra, and X-ray photoelectron spectroscopy. Increasing APTES molar ratios decreased the degree of orderliness of the functionalized mesoporous silica. Pure and amino-functionalized SBA-15 samples were employed as supports for the controlled release of water-insoluble drug emodin. Loading experiments showed that drug loading capacities mainly depended on the surface areas and pore diameters of the carriers. Controlled release profiles of emodin-loaded samples were studied in phosphate buffered saline (PBS, pH 7.4), and results indicated that the emodin release rate could be controlled by surface amino-functionalized carriers. Emodin loaded on functionalized mesoporous supports exhibited a lower release rate than that of loaded on pure SBA-15, emodin loaded on F10-SBA-15 showed the smallest release amount (71.74 wt%) after stirring in PBS for 60 h. Findings suggest that functionalized mesoporous SBA-15 is a promising carrier for achieving prolonged release time periods.

  16. Formulation and evaluation of controlled release floating microspheres of tolperisone hydrochloride

    Directory of Open Access Journals (Sweden)

    Pooja Jani

    2012-01-01

    Full Text Available Main aim of this study was to develop controlled release (CR floating multiparticulate drug delivery system of tolperisone hydrochloride. Microspheres were prepared by nonaqueous solvent evaporation technique consisting of porous calcium silicate (Florite or FLR as porous carrier, tolperisone hydrochloride (API, Ethyl cellulose (EC, and HPMC 15 cPs as rate controlling polymers. 2 3 full factorial design was applied for optimization of formulation. The effect of various formulation and process variables on the particle morphology, micromeritic properties, in vitro floating behavior, entrapment efficiency, and in vitro drug release were studied. The size of microspheres was varied from 300 to 500 μm. The microspheres were found to be highly porous and regular in shape. All the formulations showed excellent flow properties. The percentage entrapment efficiency of all batches was greater than 80%. The percentage buoyancy varied from 85% to 98% at the end of 12 h. The release rate was determined in simulated gastric fluids. The formulation demonstrated favorable in vitro floating and release characteristics. Different kinetic models were applied to study the release mechanism. All formulations followed Higuchi model, which indicates the diffusion control release of water soluble drug from polymer matrix. Multiple regression analysis was applied for study of the effect of independent variables on the dependent variables.

  17. Chitosan-polycarbophil complexes in swellable matrix systems for controlled drug release.

    Science.gov (United States)

    Lu, Z; Chen, W; Hamman, J H

    2007-10-01

    A prerequisite for progress in the design of novel drug delivery systems is the development of excipients that are capable of fulfilling multifunctional roles such as controlling the release of the drug according to the therapeutic needs. Although several polymers have been utilised in the development of specialised drug delivery systems, their scope in dosage form design can be enlarged through combining different polymers. When a polymer is cross-linked or complexed with an oppositely charged polyelectrolyte, a three-dimensional network is formed in which the drug can be incorporated to control its release. The swelling properties and release kinetics of two model drugs with different water solubilities (i.e. diltiazem and ibuprofen) from monolithic matrix tablets consisting of an interpolyelectrolyte complex between chitosan and polycarbophil are reported. Matrix tablets consisting of this polymeric complex without drug or excipients exhibited extremely high swelling properties that are completely reversible upon drying. The drug release from matrix systems with different formulations depended on the concentration of the chitosan-polycarbophil interpolyelectrolyte complex and approached zero order release kinetics for both model drugs. The chitosan-polycarbophil interpolyelectrolyte complex has demonstrated a high potential as an excipient for the production of swellable matrix systems with controlled drug release properties.

  18. Controlled release from triple layer, donut-shaped tablets with enteric polymers.

    Science.gov (United States)

    Kim, Cherng-ju

    2005-10-22

    The purpose of this research was to evaluate triple layer, donut-shaped tablets (TLDSTs) for extended release dosage forms. TLDSTs were prepared by layering 3 powders sequentially after pressing them with a punch. The core tablet consisted of enteric polymers, mainly hydroxypropyl methylcellulose acetate succinate, and the bottom and top layers were made of a water-insoluble polymer, ethyl cellulose. Drug release kinetics were dependent on the pH of the dissolution medium and the drug properties, such as solubility, salt forms of weak acid and weak base drugs, and drug loading. At a 10% drug loading level, all drugs, regardless of their type or solubility, yielded the same release profiles within an acceptable level of experimental error. As drug loading increased from 10% to 30%, the drug release rate of neutral drugs increased for all except sulfathiazole, which retained the same kinetics as at 10% loading. HCl salts of weak base drugs had much slower release rates than did those of neutral drugs (eg, theophylline) as drug loading increased. The release of labetalol HCl retarded as drug loading increased from 10% to 30%. On the other hand, Na salts of weak acid drugs had much higher release rates than did those of neutral drugs (eg, theophylline). Drug release kinetics were governed by the ionization/erosion process with slight drug diffusion, observing no perfect straight line. A mathematical expression for drug release kinetics (erosion-controlled system) of TLDSTs is presented. In summary, a TLDST is a good design to obtain zero-order or nearly zero-order release kinetics for a wide range of drug solubilities.

  19. The effect of protein corona on doxorubicin release from the magnetic mesoporous silica nanoparticles with polyethylene glycol coating

    Energy Technology Data Exchange (ETDEWEB)

    Pourjavadi, Ali, E-mail: purjavad@sharif.edu; Tehrani, Zahra Mazaheri; Mahmoudi, Negar [Sharif University of Technology, Polymer Research Laboratory, Department of Chemistry (Iran, Islamic Republic of)

    2015-04-15

    In the present work, biocompatible superparamagnetic iron oxide nanoparticles coated by mesoporous silica were used as drug nanocarriers for doxorubicin (Dox; an anticancer drug) delivery. In biological media, the interaction of protein corona layer with the surface of nanoparticles is inevitable. For this reason, we studied the effect of protein corona on drug release from magnetic mesoporous silica nanoparticles (MMSNs) in human plasma medium. Besides, we used hydrophilic and biocompatible polymer, polyethylene glycol (PEG), to decrease protein corona effects. The results showed the increased Dox release from PEGylated MMSNs compared with bare MMSNs. This result indicated that the coating of PEG reduced the wrapping of the protein corona around the nanoparticles. This phenomenon caused increase in Dox release.

  20. Controlled release of osteopontin and interleukin-10 from modified endovascular coil promote cerebral aneurysm healing.

    Science.gov (United States)

    Chen, Jingyi; Yang, Lijun; Chen, Yan; Zhang, Gengshen; Fan, Zheneng

    2016-01-15

    Cerebral aneurysm is a bulging of the artery inside the brain that results from a weakened or thin area of the artery wall. Ruptured cerebral aneurysm could lead to serious brain damage or even death, thus the proper treatment is essential. Compared with the conventional microsurgical clipping approach, the endovascular coiling treatment has many advantages, however, with a major disadvantage of high recurrence rate. One way to lower the recurrence rate, which has been tried since one decade ago, is to modify the coil to be bioactive and releasing biological molecules to stimulate tissue ingrowth and aneurysm healing. We have identified three candidates including osteopontin (OPN), IL-10 and matrix metallopeptidase 9 (MMP-9) from previous studies and generated platinum coils coated with these proteins in the carrier of poly-DL-lactic glycolic acid (PLGA). We were interested to know whether coils coated with OPN, IL-10 and MMP-9 were able to promote aneurysm healing and we have tested it in the rat carotid aneurysm model. We found that OPN and IL-10 coated coils had shown significant improvement in tissue ingrowth while MMP-9 coated coils failed to enhance tissue ingrowth compared with the control group. Our studies suggested the possible application of OPN and IL-10 coated coils in aneurysm treatment to overcome the recurrence.

  1. A smart surface in a microfluidic chip for controlled protein separation.

    Science.gov (United States)

    Mu, Li; Liu, Ying; Cai, Shaoyu; Kong, Jilie

    2007-01-01

    The smart surface created in a microfluidic chip has shown the capability of adsorbing and releasing proteins under electrical control. The inner surface of the chip channel was first coated by a thin layer of Au through sputtering and was subsequently modified with loosely packed self-assembled monolayers (SAMs) of thiols with terminal carboxylic or amino groups. Upon application of an external electric potential to the gold substrate, reversible conformational transformation between "bent" and "straight" states for the anchored mercapto chains could be modulated, through the electrostatic effect between the ionized terminal groups and the charged gold substrate. Thus, a hydrophobic or hydrophilic channel surface was established and could be reversibly switched electrochemically. Accordingly, the microchips prepared in this way can reversibly and selectively adsorb and release differently charged proteins under electrical control. Two model proteins, avidin and streptavidin, were demonstrated to be readily adsorbed by the smart chips under negative and positive potential, respectively. Also, more than 90 % of the adsorbed proteins could be released upon an electrical command. Furthermore, these chips were applied to the controlled separation of avidin and streptavidin mixtures with 1:1 and 1:1000 molar ratios. Under specific applied potentials, the chips adsorbed a certain protein from the mixture whereas the other protein was allowed to flow out, after which the adsorbed protein could be released by switching the applied potential. Thus, two eluted protein fractions were obtained and the separation of the two proteins was achieved. For the former mixture, each eluted fraction contained up to approximately 80-90 % avidin or streptavidin. For the latter mixture, the resulting separation efficiency indicated that the molar ratio of avidin and streptavidin could be increased from 1:1000 to about 32:1 after five run separations.

  2. 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.

  3. 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

  4. Recombinant chymosin used for exact and complete removal of a prochymosin derived fusion tag releasing intact native target protein

    DEFF Research Database (Denmark)

    Justesen, Sune; Lamberth, Kasper; Nielsen, Lise-Lotte B

    2009-01-01

    Fusion tags add desirable properties to recombinant proteins, but they are not necessarily acceptable in the final products. Ideally, fusion tags should be removed releasing the intact native protein with no trace of the tag. Unique endoproteinases with the ability to cleave outside their own...... characteristics for the exact removal of fusion tags. It is readily available in highly purified recombinant versions approved by the FDA for preparation of food for human consumption. We suggest that one should consider extending the use of chymosin to the preparation of pharmaceutical proteins....... recognition sequence can potentially cleave at the boundary of any native protein. Chymosin was recently shown to cleave a pro-chymosin derived fusion tag releasing native target proteins. In our hands, however, not all proteins are chymosin-resistant under the acidic cleavage conditions (pH 4.5) used...

  5. Application of photoremovable protecting group for controlled release of plant growth regulators by sunlight.

    Science.gov (United States)

    Atta, Sanghamitra; Ikbal, Mohammed; Kumar, Ashutosh; Pradeep Singh, N D

    2012-06-01

    We report a novel technique for controlled release of plant growth regulators (PGRs) by sunlight using photoremovable protecting group (PRPG) as a delivery device. In the present work, carboxyl-containing PGRs of the auxin group [indoleacetic acid (IAA) and naphthoxyacetic acid (NOAA)] were chemically caged using PRPGs of coumarin derivatives. Photophysical studies showed that caged PGRs exhibited good fluorescence properties. Irradiation of caged PGRs by sunlight in both aqueous ethanol and soil media resulted in controlled release of PGRs. The results of the bioactivity experiments indicated that caged PGRs showed better enhancement in the root and shoot length growth of Cicer arietinum compared to PGRs after 10days of sunlight exposure. Our results indicated that use of PRPG as a delivery device for controlled release of PGRs by sunlight in soil holds great interest for field application since it can overcome the rapid loss of PGRs in environmental conditions.

  6. Laponite-based nanohybrid for enhanced solubility and controlled release of itraconazole.

    Science.gov (United States)

    Jung, Hyun; Kim, Hyun-Mi; Choy, Young Bin; Hwang, Seong-Ju; Choy, Jin-Ho

    2008-02-12

    Laponite, a form of layered aluminosilicates, and itraconazole, a water insoluble drug, were hybridized through an interfacial reaction at the boundary between water and a water-immiscible liquid. The reaction was carried out under a controlled pH to maintain both physical and chemical stability of the drug. The X-ray diffraction patterns and spectroscopic analyses indicated that itraconazole was intercalated into the interlayer space of clay with a lateral monolayer structure. No significant chemical structural change of itraconazole was seen through the formation of the hybrid. The hybrid system exhibited enhanced solubility and controlled release of itraconazole. The released amount of itraconazole could be controlled in the range from 18 to 75%, depending on the kinds of cations in the release media.

  7. Extracellular control of intracellular drug release for enhanced safety of anti-cancer chemotherapy

    Science.gov (United States)

    Zhu, Qian; Qi, Haixia; Long, Ziyan; Liu, Shang; Huang, Zhen; Zhang, Junfeng; Wang, Chunming; Dong, Lei

    2016-06-01

    The difficulty of controlling drug release at an intracellular level remains a key challenge for maximising drug safety and efficacy. We demonstrate herein a new, efficient and convenient approach to extracellularly control the intracellular release of doxorubicin (DOX), by designing a delivery system that harnesses the interactions between the system and a particular set of cellular machinery. By simply adding a small-molecule chemical into the cell medium, we could lower the release rate of DOX in the cytosol, and thereby increase its accumulation in the nuclei while decreasing its presence at mitochondria. Delivery of DOX with this system effectively prevented DOX-induced mitochondria damage that is the main mechanism of its toxicity, while exerting the maximum efficacy of this anti-cancer chemotherapeutic agent. The present study sheds light on the design of drug delivery systems for extracellular control of intracellular drug delivery, with immediate therapeutic implications.

  8. FORMULATION AND EVALUATION OF METOPROLOL SUCCINATE CONTROLLED RELEASE TABLETS USING NATURAL AND SYNTHETIC POLYMER

    Directory of Open Access Journals (Sweden)

    A. Sathyaraj

    2012-01-01

    Full Text Available The objective of the present study to develop controlled release tablets of Metoprolol succinate using Natural polymer, guar gum and synthetic polymer, carbopol as a rate controlling polymers.. It was also desired to study the effect of polymer concentration. Metoprolol succinate, β1- selective adrenergic receptor- blocking agent used in the management of hypertension, angina pectoris, cardiac arrthymias, myocardial infarction, heart failure, hyperthyroidism and in the prophylactic treatment of migraine. The half-life of drug is relatively short approximately 4-6 hrs and in normal course of therapy drug administration is required every 4-6 hrs, thus warrants the use of controlled release formulation for prolong action and to improve patient compliance. In the present investigation Natural polymer, guar gum and synthetic polymer, carbopol have been selected as matrix forming materials for the drug. The formulations are made by employing the conventional wet granulation method, to achieve prolonged release of medicaments.

  9. Controlled Release of Ciprofloxacin from Core-Shell Nanofibers with Monolithic or Blended Core.

    Science.gov (United States)

    Zupančič, Špela; Sinha-Ray, Sumit; Sinha-Ray, Suman; Kristl, Julijana; Yarin, Alexander L

    2016-04-04

    Sustained controlled drug release is one of the prominent contributions for more successful treatment outcomes in the case of several diseases. However, the incorporation of hydrophilic drugs into nanofibers, a promising novel delivery system, and achieving a long-term sustained release still pose a challenging task. In this work we demonstrated a robust method of avoiding burst release of drugs and achieving a sustained drug release from 2 to 4 weeks using core-shell nanofibers with poly(methyl methacrylate) (PMMA) shell and monolithic poly(vinyl alcohol) (PVA) core or a novel type of core-shell nanofibers with blended (PVA and PMMA) core loaded with ciprofloxacin hydrochloride (CIP). It is also shown that, for core-shell nanofibers with monolithic core, drug release can be manipulated by varying flow rate of the core PVA solution, whereas for core-shell nanofibers with blended core, drug release can be manipulated by varying the ratios between PMMA and PVA in the core. During coaxial electrospinning, when the solvent from the core evaporates in concert with the solvent from the shell, the interconnected pores spanning the core and the shell are formed. The release process is found to be desorption-limited and agrees with the two-stage desorption model. Ciprofloxacin-loaded nanofiber mats developed in the present work could be potentially used as local drug delivery systems for treatment of several medical conditions, including periodontal disease and skin, bone, and joint infections.

  10. PKCβ phosphorylates PI3Kγ to activate it and release it from GPCR control.

    Directory of Open Access Journals (Sweden)

    Romy Walser

    Full Text Available All class I phosphoinositide 3-kinases (PI3Ks associate tightly with regulatory subunits through interactions that have been thought to be constitutive. PI3Kγ is key to the regulation of immune cell responses activated by G protein-coupled receptors (GPCRs. Remarkably we find that PKCβ phosphorylates Ser582 in the helical domain of the PI3Kγ catalytic subunit p110γ in response to clustering of the high-affinity IgE receptor (FcεRI and/or store-operated Ca²⁺- influx in mast cells. Phosphorylation of p110γ correlates with the release of the p84 PI3Kγ adapter subunit from the p84-p110γ complex. Ser582 phospho-mimicking mutants show increased p110γ activity and a reduced binding to the p84 adapter subunit. As functional p84-p110γ is key to GPCR-mediated p110γ signaling, this suggests that PKCβ-mediated p110γ phosphorylation disconnects PI3Kγ from its canonical inputs from trimeric G proteins, and enables p110γ to operate downstream of Ca²⁺ and PKCβ. Hydrogen deuterium exchange mass spectrometry shows that the p84 adaptor subunit interacts with the p110γ helical domain, and reveals an unexpected mechanism of PI3Kγ regulation. Our data show that the interaction of p110γ with its adapter subunit is vulnerable to phosphorylation, and outline a novel level of PI3K control.

  11. Controlled-release phentermine/topiramate in severely obese adults: a randomized controlled trial (EQUIP).

    Science.gov (United States)

    Allison, David B; Gadde, Kishore M; Garvey, William Timothy; Peterson, Craig A; Schwiers, Michael L; Najarian, Thomas; Tam, Peter Y; Troupin, Barbara; Day, Wesley W

    2012-02-01

    A 56-week randomized controlled trial was conducted to evaluate safety and efficacy of a controlled-release combination of phentermine and topiramate (PHEN/TPM CR) for weight loss (WL) and metabolic improvements. Men and women with class II and III obesity (BMI ≥ 35 kg/m(2)) were randomized to placebo, PHEN/TPM CR 3.75/23 mg, or PHEN/TPM CR 15/92 mg, added to a reduced-energy diet. Primary end points were percent WL and proportions of patients achieving 5% WL. Secondary end points included waist circumference (WC), systolic and diastolic blood pressure (BP), fasting glucose, and lipid measures. In the primary analysis (randomized patients with at least one postbaseline weight measurement who took at least one dose of assigned drug or placebo), patients in the placebo, 3.75/23, and 15/92 groups lost 1.6%, 5.1%, and 10.9% of baseline body weight (BW), respectively, at 56 weeks (P fasting glucose, triglycerides, total cholesterol, low-density lipoprotein (LDL), and high-density lipoprotein (HDL). The most common adverse events were paresthesia, dry mouth, constipation, dysgeusia, and insomnia. Dropout rate from the study was 47.1% for placebo patients, 39.0% for 3.75/23 patients, and 33.6% of 15/92 patients. PHEN/TPM CR demonstrated dose-dependent effects on weight and metabolic variables in the direction expected to be beneficial with no evidence of serious adverse events induced by treatment.

  12. Synthetic Zeolites as Controlled-Release Delivery Systems for Anti-Inflammatory Drugs.

    Science.gov (United States)

    Khodaverdi, Elham; Soleimani, Hossein Ali; Mohammadpour, Fatemeh; Hadizadeh, Farzin

    2016-06-01

    Scientists have always been trying to use artificial zeolites to make modified-release drug delivery systems in the gastrointestinal tract. An ideal carrier should have the capability to release the drug in the intestine, which is the main area of absorption. Zeolites are mineral aluminosilicate compounds with regular structure and huge porosity, which are available in natural and artificial forms. In this study, soaking, filtration and solvent evaporation methods were used to load the drugs after activation of the zeolites. Weight measurement, spectroscopy FTIR, thermogravimetry and scanning electronic microscope were used to determine drug loading on the systems. Finally, consideration of drug release was made in a simulated gastric fluid and a simulated intestinal fluid for all matrixes (zeolites containing drugs) and drugs without zeolites. Diclofenac sodium (D) and piroxicam (P) were used as the drug models, and zeolites X and Y as the carriers. Drug loading percentage showed that over 90% of drugs were loaded on zeolites. Dissolution tests in stomach pH environment showed that the control samples (drug without zeolite) released considerable amount of drugs (about 90%) within first 15 min when it was about 10-20% for the matrixes. These results are favorable as NSAIDs irritate the stomach wall and it is ideal not to release much drugs in the stomach. Furthermore, release rate of drugs from matrixes has shown slower rate in comparison with control samples in intestine pH environment.

  13. Zinc polycarboxylate dental cement for the controlled release of an active organic substance: proof of concept.

    Science.gov (United States)

    Ali, Mohammad Naseem; Edwards, Mark; Nicholson, John W

    2010-04-01

    The potential of employing zinc polycarboxylate dental cement as a controlled release material has been studied. Benzalkonium chloride was used as the active ingredient, and incorporated at concentrations of 1, 2 and 3% by mass within the cement. At these levels, there was no observable effect on the speed of setting. Release was followed using an ion-selective electrode to determine changes in chloride ion concentration with time. This technique showed that the additive was released when the cured cement was placed in water, with release occurring by a diffusion mechanism for the first 3 h, but continuing beyond that for up to 1 week. Diffusion coefficients were in the range 5.62 x 10(-6) cm(2) s(-1) (for 1% concentration) to 10.90 x 10(-6) cm(2) s(-1) (for 3% concentration). Up to 3% of the total loading of benzalkonium chloride was released from the zinc polycarboxylate after a week, which is similar to that found in previous studies with glass-ionomer cement. It is concluded that zinc polycarboxylate cement is capable of acting as a useful material for the controlled release of active organic compounds.

  14. 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.

  15. Design and evaluation of osmotic pump-based controlled release system of Ambroxol Hydrochloride.

    Science.gov (United States)

    Cheng, Xiongkai; Sun, Min; Gao, Yan; Cao, Fengliang; Zhai, Guangxi

    2011-08-01

    The purpose of the present study was to design and evaluate an osmotic pump-based drug delivery system for controlling the release of Ambroxol Hydrochloride (Amb). Citric acid, lactose and polyethylene glycol 6000 (PEG 6000) were employed as osmotic agents. Surelease EC containing polyethylene glycol 400 (PEG 400) controlling the membrane porosity was used as semi-permeable membrane. The formulation of tablet core was optimized by orthogonal design and evaluated by weighted mark method. The influences of the amount of PEG 400 and membrane thickness on Amb release were investigated. The optimal osmotic pump tablet (OPT) was evaluated in different release media and at different stirring rates. The major release power confirmed was osmotic pressure. The release of Amb from OPT was verified at a rate of approximately zero-order, and cumulative release percentage at 12?h was 92.6%. The relative bioavailability of Amb OPT in rabbits relative to the commercial sustained capsule was 109.6%. Our results showed that Amb OPT could be a practical preparation with a good prospect.

  16. Preparation and evaluation of waxes/fat microspheres loaded with lithium carbonate for controlled release

    Directory of Open Access Journals (Sweden)

    Gowda D

    2007-01-01

    Full Text Available To minimize the unwanted toxic effects of anti maniac drug lithium carbonate by kinetic control of drug release, it was entrapped into gastro resistant, biodegradable, waxes and fat such as beeswax, cetostearyl alcohol, spermaceti and cetylalcohol microspheres using meltable emulsified dispersion cooling induced solidification technique utilizing a wetting agent. Solid, discrete, reproducible free flowing microspheres were obtained. The yield of the microspheres was up to 90.0%. More than 98.0% of the isolated microspheres were of particle size range 115 to 855 mm. The microspheres had smooth surfaces, with free flowing and good packing properties. Scanning electron microscope confirmed their spherical structures within a size range of 339-355 mm. The drug loaded in waxes and fat microspheres was stable and compatible, as confirmed by DSC and FTIR studies. The release of drug was controlled for more than 8 hours. Intestinal drug release from waxes/ fat microspheres was studied and compared with the releases behavior of commercially available formulation Intalith CR ®-450. The release kinetics followed different transport mechanisms. The drug release performance was greatly affected by the materials used in microsphere preparations, which allows absorption in the intestinal tract.

  17. Controlled release/removal technology; Seigyo hoshutsu {center_dot} jokyo gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Tojo, K. [Kyushu Inst. of Tech., Fukuoka (Japan)

    2000-02-05

    The controlled release is to control optimally releasing velocity of active ingredient in medication or agricultural chemicals for therapy or vermin control. The novel transdermal therapeutic system can be developed considering diapause term of medication setting type or time pharmacology by storing information of time lag for medication permeability in medication keeping layer. Furthermore by resent iontophoresis technology using electric fields for controlling drug permeability through the skin, migration volume of active ingredient to blood can be controlled pulsed shape by On- Off of electric fields. In another hand, it comes to be clarified that drugs in the body can be extracted by contrarotating operation of electrodes. From now, effective removal system of barren materials from organism or time controlling therapeutic system with feed buck function can be realized by being optimal novel technology of medical engineering therapy. (NEDO)

  18. Role of nitric oxide in control of prolactin release by the adenohypophysis.

    Science.gov (United States)

    Duvilanski, B H; Zambruno, C; Seilicovich, A; Pisera, D; Lasaga, M; Diaz, M C; Belova, N; Rettori, V; McCann, S M

    1995-01-01

    Nitric oxide synthase-containing cells were visualized in the anterior pituitary gland by immunocytochemistry. Consequently, we began an evaluation of the possible role of NO in the control of anterior pituitary function. Prolactin is normally under inhibitory hypothalamic control, and in vitro the gland secretes large quantities of the hormone. When hemipituitaries were incubated for 30 min in the presence of sodium nitroprusside, a releaser of NO, prolactin release was inhibited. This suppression was completely blocked by the scavenger of NO, hemoglobin. Analogs of arginine, such as NG-monomethyl-L-arginine (NMMA, where NG is the terminal guanidino nitrogen) and nitroarginine methyl ester, inhibit NO synthase. Incubation of hemipituitaries with either of these compounds significantly increased prolactin release. Since in other tissues most of the actions of NO are mediated by activation of soluble guanylate cyclase with the formation of cyclic GMP, we evaluated the effects of cyclic GMP on prolactin release. Cyclic GMP (10 mM) produced an approximately 40% reduction in prolactin release. Prolactin release in vivo and in vitro can be stimulated by several peptides, which include vasoactive intestinal polypeptide and substance P. Consequently, we evaluated the possible role of NO in these stimulations by incubating the glands in the presence of either of these peptides alone or in combination with NMMA. In the case of vasoactive intestinal polypeptide, the significant stimulation of prolactin release was augmented by NMMA to give an additive effect. In the case of substance P, there was a smaller but significant release of prolactin that was not significantly augmented by NMMA. We conclude that NO has little effect on the stimulatory action of these two peptides on prolactin release. Dopamine (0.1 microM), an inhibitor of prolactin release, reduced prolactin release, and this inhibitory action was significantly blocked by either hemoglobin (20 micrograms/ml) or

  19. Synthesis and Performance of Polyurethane Coated Urea as Slow/controlled Release Fertilizer

    Institute of Scientific and Technical Information of China (English)

    LI Qingshan; WU Shu; RU Tiejun; WANG Limin; XING Guangzhong; WANG Jinming

    2012-01-01

    Polyurethane coated urea slow/controlled release fertilizer was prepared based on urea granules,isocyanate,polyols and paraffin.Isocyanate reacted with polyols to synthesize the polyurethane skin layer on urea granules surface.Paraffin serves as a lubricant during syntheses of polyurethane skin layers.The structure and nutrient release characteristics of the polyurethane skin layers were investigated by FTIR,SEM and TG.Urea nitrogen slow-release behavior of the polyurethane coated urea was tested.The experimental results indicated that compact and dense polyurethane skin layers with a thickness of 10-15 μm were formed on urea surface,the urea nitrogen slow-release time can reach 40-50 days.Paraffin proves to play a key role in inhibiting water to penetrate into urea,but excessive addition would decrease the polyurethane crosslinking density.

  20. Control of neurotransmitter release by an internal gel matrix in synaptic vesicles.

    Science.gov (United States)

    Reigada, David; Díez-Pérez, Ismael; Gorostiza, Pau; Verdaguer, Albert; Gómez de Aranda, Inmaculada; Pineda, Oriol; Vilarrasa, Jaume; Marsal, Jordi; Blasi, Joan; Aleu, Jordi; Solsona, Carles

    2003-03-18

    Neurotransmitters are stored in synaptic vesicles, where they have been assumed to be in free solution. Here we report that in Torpedo synaptic vesicles, only 5% of the total acetylcholine (ACh) or ATP content is free, and that the rest is adsorbed to an intravesicular proteoglycan matrix. This matrix, which controls ACh and ATP release by an ion-exchange mechanism, behaves like a smart gel. That is, it releases neurotransmitter and changes its volume when challenged with small ionic concentration change. Immunodetection analysis revealed that the synaptic vesicle proteoglycan SV2 is the core of the intravesicular matrix and is responsible for immobilization and release of ACh and ATP. We suggest that in the early steps of vesicle fusion, this internal matrix regulates the availability of free diffusible ACh and ATP, and thus serves to modulate the quantity of transmitter released.

  1. Misrepresentation of randomized controlled trials in press releases and news coverage: a cohort study.

    Science.gov (United States)

    Yavchitz, Amélie; Boutron, Isabelle; Bafeta, Aida; Marroun, Ibrahim; Charles, Pierre; Mantz, Jean; Ravaud, Philippe

    2012-01-01

    Previous studies indicate that in published reports, trial results can be distorted by the use of "spin" (specific reporting strategies, intentional or unintentional, emphasizing the beneficial effect of the experimental treatment). We aimed to (1) evaluate the presence of "spin" in press releases and associated media coverage; and (2) evaluate whether findings of randomized controlled trials (RCTs) based on press releases and media coverage are misinterpreted. We systematically searched for all press releases indexed in the EurekAlert! database between December 2009 and March 2010. Of the 498 press releases retrieved and screened, we included press releases for all two-arm, parallel-group RCTs (n = 70). We obtained a copy of the scientific article to which the press release related and we systematically searched for related news items using Lexis Nexis. "Spin," defined as specific reporting strategies (intentional or unintentional) emphasizing the beneficial effect of the experimental treatment, was identified in 28 (40%) scientific article abstract conclusions and in 33 (47%) press releases. From bivariate and multivariable analysis assessing the journal type, funding source, sample size, type of treatment (drug or other), results of the primary outcomes (all nonstatistically significant versus other), author of the press release, and the presence of "spin" in the abstract conclusion, the only factor associated, with "spin" in the press release was "spin" in the article abstract conclusions (relative risk [RR] 5.6, [95% CI 2.8-11.1], p < 0.001). Findings of RCTs based on press releases were overestimated for 19 (27%) reports. News items were identified for 41 RCTs; 21 (51%) were reported with "spin," mainly the same type of "spin" as those identified in the press release and article abstract conclusion. Findings of RCTs based on the news item was overestimated for ten (24%) reports. "Spin" was identified in about half of press releases and media coverage. In

  2. Misrepresentation of randomized controlled trials in press releases and news coverage: a cohort study.

    Directory of Open Access Journals (Sweden)

    Amélie Yavchitz

    Full Text Available BACKGROUND: Previous studies indicate that in published reports, trial results can be distorted by the use of "spin" (specific reporting strategies, intentional or unintentional, emphasizing the beneficial effect of the experimental treatment. We aimed to (1 evaluate the presence of "spin" in press releases and associated media coverage; and (2 evaluate whether findings of randomized controlled trials (RCTs based on press releases and media coverage are misinterpreted. METHODS AND FINDINGS: We systematically searched for all press releases indexed in the EurekAlert! database between December 2009 and March 2010. Of the 498 press releases retrieved and screened, we included press releases for all two-arm, parallel-group RCTs (n = 70. We obtained a copy of the scientific article to which the press release related and we systematically searched for related news items using Lexis Nexis. "Spin," defined as specific reporting strategies (intentional or unintentional emphasizing the beneficial effect of the experimental treatment, was identified in 28 (40% scientific article abstract conclusions and in 33 (47% press releases. From bivariate and multivariable analysis assessing the journal type, funding source, sample size, type of treatment (drug or other, results of the primary outcomes (all nonstatistically significant versus other, author of the press release, and the presence of "spin" in the abstract conclusion, the only factor associated, with "spin" in the press release was "spin" in the article abstract conclusions (relative risk [RR] 5.6, [95% CI 2.8-11.1], p < 0.001. Findings of RCTs based on press releases were overestimated for 19 (27% reports. News items were identified for 41 RCTs; 21 (51% were reported with "spin," mainly the same type of "spin" as those identified in the press release and article abstract conclusion. Findings of RCTs based on the news item was overestimated for ten (24% reports. CONCLUSION: "Spin" was identified in

  3. 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.

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

    OpenAIRE

    Renato Luis Grisi Macedo; Elainy Botelho Carvalho Pereira; Ailton Vitor Pereira; Nelson Venturin; Antonio Nilson Zamunér Filho

    2012-01-01

    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-r...

  5. Formulation and evaluation of controlled release matrix mucoadhesive tablets of domperidone using Salvia plebeian gum

    Directory of Open Access Journals (Sweden)

    Gurpreet Arora

    2011-01-01

    Full Text Available The aim of study was to prepare controlled release matrix mucoadhesive tablets of domperidone using Salvia plebeian gum as natural polymer. Tablets were formulated by direct compression technology employing the natural polymer in different concentrations (5, 10, 15 and 20% w/w. The prepared batches were evaluated for drug assay, diameter, thickness, hardness and tensile strength, swelling index, mucoadhesive strength (using texture analyzer and subjected to in vitro drug release studies. Real-time stability studies were also conducted on prepared batches. In vitro drug release data were fitted in various release kinetic models for studying the mechanism of drug release. Tensile strength was found to increase from 0.808 ± 0.098 to 1.527 ± 0.10 mN/cm 2 and mucoadhesive strength increased from 13.673 ± 1.542 to 40.378 ± 2.345 N, with an increase in the polymer concentration from 5 to 20% (A1 to A4. Swelling index was reported to increase with both increase in the concentration of gum and the time duration. The in vitro drug release decreased from 97.76 to 83.4% (A1 to A4 with the increase in polymer concentration. The drug release from the matrix tablets was found to follow zero-order and Higuchi models, indicating the matrix-forming potential of natural polymer. The value of n was found to be between 0.5221 and 0.8992, indicating the involvement of more than one drug release mechanism from the formulation and possibly the combination of both diffusion and erosion. These research findings clearly indicate the potential of S. plebeian gum to be used as binder, release retardant and mucoadhesive natural material in tablet formulations.

  6. A pediatric non-protein losing Menetrier's disease successfully treated with octreotide long acting release

    Institute of Scientific and Technical Information of China (English)

    Giovanni Di Nardo; Salvatore Oliva; Marina Aloi; Federica Ferrari; Simone Frediani; Adriana Marcheggiano; Salvatore Cucchiara

    2012-01-01

    Pediatric Menetrier's disease (MD) is an uncommon,acute,self-limited hypertrophic gastropathy characterized by enlarged gastric folds associated with epithelial hyperplasia and usually accompanied by protein losing gastropathy.Gastric cytomegalovirus infection is found in one third of MD children and its treatment is often associated with remission.Diagnosis often requires fullthickness biopsy due to inability to detect typical histological findings with conventional endoscopic biopsy.We report an uncommon case of non self-limited pediatric MD needing endoscopic mucosal resection for diagnosis which was then successfully treated with octreotide long-acting release (LAR).To the best of our knowledge,this is the first pediatric MD case successfully treated with octreotide LAR.Our experience suggests octreotide LAR as treatment for refractory MD before gastrectomy.

  7. Controllable mineral coatings on scaffolds as carriers for growth factor release for bone tissue engineering

    Science.gov (United States)

    Saurez-Gonzalez, Darilis

    The work presented in this document, focused on the development and characterization of mineral coatings on scaffold materials to serve as templates for growth factor binding and release. Mineral coatings were formed using a biomimetic approach that consisted in the incubation of scaffolds in modified simulated body fluids (mSBF). To modulate the properties of the mineral coating, which we hypothesized would dictate growth factor release, we used carbonate (HCO3) concentration in mSBF of 4.2 mM, 25mM, and 100mM. Analysis of the mineral coatings formed using scanning electron microscopy indicated growth of a continuous layer of mineral with different morphologies. X-ray diffraction analysis showed peaks associated with hydroxyapatite. FTIR data confirmed the substitution of HCO3 in the mineral. As the extent of HCO3 substitution increased, the coating exhibited more rapid dissolution kinetics in an environment deficient in calcium and phosphate. The mineral coatings provided an effective mechanism for bioactive growth factor binding and release. Peptide versions of vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP2) were bound with efficiencies up to 90% to mineral-coated PCL scaffolds. Recombinant human vascular endothelial growth factor (rhVEGF) also bound to mineral coated scaffolds with lower efficiency (20%) and released with faster release kinetics compared to peptides growth factor. Released rhVEGF induced human umbilical vein endothelial cell (HUVEC) proliferation in vitro and enhanced blood vessel formation in vivo in an intramuscular sheep model. In addition to the use the mineral coatings for single growth factor release, we expanded the concept and bound both an angiogenic (rhVEGF) and osteogenic (mBMP2) growth factor by a simple double dipping process. Sustained release of both growth factors was demonstrated for over 60 days. Released rhVEGF enhanced blood vessel formation in vivo in sheep and its biological activity was

  8. Comparing encapsulation efficiency and ultrasound-triggered release for protein between phospholipid-based microbubbles and liposomes.

    Science.gov (United States)

    Lu, Cui-Tao; Zhao, Ying-Zheng; Gao, Hui-Sheng; Tian, Ji-Lai; Zhou, Zhi-Cai; Zhao, Gang-Tao; Tang, Qin-Qin; Jin, Zhuo; Xu, Yan-Yan; Huang, Pin-Tong; Han, Jing; Wang, Liang; Li, Xiao-Kun

    2010-01-01

    This work was to compare the encapsulation efficiency and ultrasound-triggered release for protein between microbubbles and liposomes. Bovine serum albumin (BSA) was used as a model. Final ratios between BSA and HPC in microbubbles and liposomes were 1:5, 1:7 and 1:10, respectively. Morphologic characteristics and contrast enhancement of loaded microbubbles and liposomes were measured. Encapsulation efficiency and ultrasound-stimulated release profile were detected. The mean size of loaded microbubbles and liposomes was 3.4 microm and 1.7 microm, respectively. Encapsulation efficiency of microbubbles had an inverse relationship with the ratio between BSA and HPC, while loaded liposomes remained nearly unchanged in the designed range of the ratio between BSA and HPC. Microbubbles resulted in significant enhancement of CnTi images. After ultrasound, more than 90% of the entrapped BSA was released from microbubbles, but less than 5% of BSA released from liposomes. Microbubbles are a promising delivery system for proteins.

  9. Ciprofloxacin Controlled-Solid Lipid Nanoparticles: Characterization, In Vitro Release, and Antibacterial Activity Assessment

    Science.gov (United States)

    2017-01-01

    The objective of this research was to formulate ciprofloxacin (CIP) in solid lipid nanoparticles (SLNs) in an attempt to develop a controlled drug delivery system. An ultrasonic melt-emulsification method was used for preparing CIP-loaded SLNs. Key findings included that SLNs were successfully produced with average particle sizes ranging from 165 to 320 nm and polydispersity index in the range of 0.18–0.33. High entrapment efficiency values were reported in all formulations. The atomic force scanning microscopic images showed spherical shape with the size range closer to those found by the particle size analyzer. CIP release exhibited controlled-release behavior with various lipids. Ciprofloxacin solid lipid nanoparticles formula containing stearic acid (CIPSTE) displayed the strongest burst effect and the most rapid release rate. The release data revealed a better fit to the Higuchi diffusion model. After storing the CIPSTE formula at room temperature for 120 days, no significant difference in particle size and zeta potential was found. CIP-loaded SLNs exhibited superior antibacterial activity. Incorporation of CIP into SLNs leads to controlled release and a superior antibacterial effect of CIP. PMID:28194408

  10. A controlled release system of titanocene dichloride by electrospun fiber and its antitumor activity in vitro.

    Science.gov (United States)

    Chen, Ping; Wu, Qing-Sheng; Ding, Ya-Ping; Chu, Maoquan; Huang, Zheng-Ming; Hu, Wen

    2010-11-01

    In order to improve both safety and efficacy of cancer chemotherapy of titanocene dichloride and overcome the shortcomings such as instability and short half-life in the human body, we report a controlled release system of titanocene dichloride by electrospun fiber and its in vitro antitumor activity against human lung tumor spca-1 cells. The system was developed by electrospinning. The release profiles of titanocene dichloride in PBS were researched by UV-Vis spectrophotometer. In vitro antitumor activities of the fibers were examined by MTT method. Titanocene dichloride was well incorporated in biodegradable poly(L-lactic acid) fibers. XRD results suggest that titanocene dichloride exists in the amorphous form in the fibers. The controlled release of titanocene dichloride can be gained for long time. MTT showed actual titanocene dichloride content 40, 80, 160 and 240 mg/L from the fibers mat, cell growth inhibition rates of 11.2%, 22.1%, 44.2% and 68.2% were achieved, respectively. The titanocene dichloride released has obvious inhibition effect against lung tumor cells. The system has an effect of controlled release of titanocene dichloride and may be used as an implantable anticancer drug in clinical applications in the future.

  11. FORMULATION AND EVALUATION OF ORAL CONTROLLED RELEASE DOSAGE FORM OF ANTI-HYPERTENSIVE AGENT

    Directory of Open Access Journals (Sweden)

    Lakshmi Parvathi A

    2012-12-01

    Full Text Available The aim of present investigation is preparation, characterization and evaluation of oral controlled release matrix tablets of Propranolol HCl in order to improve efficacy and to reduce the side effects. Tablets were prepared by direct compression method using different polymers like Guar gum, HPMC K4M, PVP and MCC used as the directly compressible vehicle. The granules were evaluated for pre-formulation characteristics and the tablets were subjected to post compression parameters, drug content and in-vitro dissolution release studies. In-vitro dissolution studies were carried out for 12 hrs and the results showed that among the nine formulations F8 and F9 showed good dissolution profile to control the drug release respectively. The drug release follows first order kinetics and the mechanism was found to be diffusion controlled for all the formulations (except F-9. The mechanism of drug release from F-9 was diffusion coupled with erosion. The Stability studies were carried out according to ICH guideline which indicates that the selected formulations (F8 and F9 were stable. In conclusion the results suggest that the developed matrix tablets of Propranolol HCl could perform therapeutically better than conventional dosage form, leading to improved efficacy and better patient compliance.

  12. Ciprofloxacin Controlled-Solid Lipid Nanoparticles: Characterization, In Vitro Release, and Antibacterial Activity Assessment

    Directory of Open Access Journals (Sweden)

    Gamal A. Shazly

    2017-01-01

    Full Text Available The objective of this research was to formulate ciprofloxacin (CIP in solid lipid nanoparticles (SLNs in an attempt to develop a controlled drug delivery system. An ultrasonic melt-emulsification method was used for preparing CIP-loaded SLNs. Key findings included that SLNs were successfully produced with average particle sizes ranging from 165 to 320 nm and polydispersity index in the range of 0.18–0.33. High entrapment efficiency values were reported in all formulations. The atomic force scanning microscopic images showed spherical shape with the size range closer to those found by the particle size analyzer. CIP release exhibited controlled-release behavior with various lipids. Ciprofloxacin solid lipid nanoparticles formula containing stearic acid (CIPSTE displayed the strongest burst effect and the most rapid release rate. The release data revealed a better fit to the Higuchi diffusion model. After storing the CIPSTE formula at room temperature for 120 days, no significant difference in particle size and zeta potential was found. CIP-loaded SLNs exhibited superior antibacterial activity. Incorporation of CIP into SLNs leads to controlled release and a superior antibacterial effect of CIP.

  13. Intercalation of urea into kaolinite for preparation of controlled release fertilizer

    Directory of Open Access Journals (Sweden)

    Mahdavi Fariba

    2014-01-01

    Full Text Available In this study urea was intercalated between layers of kaolinite by dry grinding technique to be used for preparing controlled release fertilizer. X-ray powder diffraction (XRPD patterns confirmed the intercalation of urea into kaolinite by the significant expansion of the basal spacing of kaolinite layers from 0.710 nm to 1.090 nm. Fourier transform infrared spectroscopy (FT-IR also confirmed the hydrogen bonding between urea and kaolinite. Based on CHNS elemental analysis, 20% (wt. urea was intercalated between kaolinite layers. The urea-intercalated kaolinite was mixed with hydroxypropyl methylcellulose (HPMC binder and was granulated to prepare the nitrogen-based controlled release fertilizer. To study the nitrogen release behavior of granules, ultraviolet/visible (UV-Vis spectroscopy was used through the diacetyl monoxime (DAM colorimetric method. The result of UV-Vis spectroscopy showed that intercalation of urea into kaolinite decreased the nitrogen release from 25.50 to 13.66 % after 24 hours and from 98.15 to 70.01% after 30 days incubation in water. According to the results, the prepared controlled release fertilizer (CRF behaved according to the standard for CRFs.

  14. Magnetic Control of Convection during Protein Crystallization

    Science.gov (United States)

    Ramachandran, N.; Leslie, F. W.

    2004-01-01

    An important component in biotechnology, particularly in the area of protein engineering and rational drug design is the knowledge of the precise three-dimensional molecular structure of proteins. The quality of structural information obtained from X-ray diffraction methods is directly dependent on the degree of perfection of the protein crystals. As a consequence, the growth of high quality macromolecular Crystals for diffraction analyses has been the central focus for bio-chemists, biologists, and bioengineers. Macromolecular crystals are obtained from solutions that contain the crystallizing species in equilibrium with higher aggregates, ions, precipitants, other possible phases of the protein, foreign particles, the walls of container, and a likely host of other impurities. By changing transport modes in general, i.e., reduction of convection and Sedimentation as is achieved in "microgravity", we have been able to dramatically affect the movement and distribution of macromolecules in the fluid, and thus their transport, f o d o n of crystal nuclei, and adsorption to the crystal surface. While a limited number of high quality crystals from space flights have been obtained, as the recent National Research Council (NRC) review of the NASA microgravity crystallization program pointed out, the scientific approach and research in crystallization of proteins has been mainly empirical yielding inconclusive results. We postulate that we can reduce convection in ground-based experiments and we can understand the different aspects of convection control through the use of strong magnetic fields and field gradients. We postulate that limited convection in a magnetic field will provide the environment for the growth of high quality crystals. The approach exploits the variation of fluid magnetic susceptibility with counteracts on for this purpose and the convective damping is realized by appropriately positioning the crystal growth cell so that the magnetic susceptibility

  15. Improved wound healing in pressure-induced decubitus ulcer with controlled release of basic fibroblast growth factor

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Wei [Department of Respiratory Diseases, Tangdu Hospital, Fourth Military Medical University, Xi' an 710038 (China); Wang Hailun [Department of Dermatology, Tangdu Hospital, Fourth Military Medical University, Xi' an 710038 (China); Jin Faguang [Department of Respiratory Diseases, Tangdu Hospital, Fourth Military Medical University, Xi' an 710038 (China)], E-mail: nidewenzhang@163.com; Yu Chunyan [Department of Dermatology, Tangdu Hospital, Fourth Military Medical University, Xi' an 710038 (China); Chu Dongling [Department of Respiratory Diseases, Tangdu Hospital, Fourth Military Medical University, Xi' an 710038 (China); Wang Lin [Department of Internal Medicine, 316 Hospital of PLA, Beijing 100093 (China); Lu Xian [93942 Unit Hospital of PLA, Xianyang 710012 (China)

    2008-07-14

    The purpose was to evaluate the efficacy of the wound dressing containing basic fibroblast growth factor (bFGF)-loaded microspheres on promoting healing in pressure-induced decubitus ulcer. In this study, the pressure-induced ulcer in swine was used as a model to demonstrate the hypothesis that controlled release of bFGF has the potential to provide optimal healing milieu for chronic wounds in the repair process. Average size of the microspheres was 14.36 {+-} 3.56 {mu}m and the network gelatin sponges were characterized with an average pore size of 80-160 {mu}m. Both the in vitro release efficiency and the protein bioactivity revealed that bFGF was released from the microspheres in a controlled manner and it was biologically active as assessed by its ability to induce the proliferation of fibroblasts. Pressure-induced ulcer was created at 500 g/cm{sup 2} pressure loaded on swine dorsal skin 12 h daily for 2 consecutive days. After removal of the pressure load, the gelatin sponge containing bFGF gelatin microspheres or bFGF in solution was implanted into the wound. Swine were sacrificed at 7, 14, and 21 days after implantation, and a full-thickness biopsy was taken and stained for histological analysis. It was observed that controlled release of bFGF provided an accelerated recovery in the wound areas. Histological investigations showed that the dressings were biocompatible and had capability of proliferating fibroblasts and inducing neovascularisation. The present study implied the clinical potential of gelatin sponge with bFGF microspheres to promote the healing in pressure-induced decubitus ulcer.

  16. The Release of Egg White Lysozyme Containing EDTA from Composite Edible Film Based on Whey Protein, Konjac Flour and Lipid

    Directory of Open Access Journals (Sweden)

    Mulia W. Apriliyani

    2014-01-01

    Full Text Available The objectives of this research were to find out the effect of EDTA addition on antibacterial spectrum broadening of lysozyme on Gram negative bacteria and the release of lysozyme from composite edible film made of whey protein, konjac glucomannan and several lipids type and content. The research were conducted with 2 steps. Step I: The addition of EDTA on lysozyme aquaeous (Lysozyme (mg/mL: EDTA (mg/mL = 11.14:8.14; 11.14:11.14 and 11.14:14.14 using Randomyzed Block Design, the variables were, antibacterial of lysozyme on Micrococcus lysodeikticus and Escherichia coli. Step II: Lipid content (5 and 10% and kind of lipid (butter, margarine, palm oil and beeswax using nested Randomyzed Block Design, the variables were lysozyme release, Water Vapor Permeability (WVP, protein solublity and microstructure of composite edible film. The results were, step I: the treatment didn’t gave significantly effect (p>0.05 on lysozyme activity. EDTA decrease cell membrane stabilization and lysozyme made lysis of cell membrane. EDTA chelate Ca2+ and Mg2+ salts as bridge between Lypopolysachcharide (LPS in outer membrane so LPS released from cell wall of Gram negative bacteria. Step II: The treatment didn’t gave significantly effect (p>0.05 on release of lysozyme and water vapour permeability, but gave significantly effect (p<0.05 on protein solubility. The release of lysozyme from composite edible film gave the best lysozyme release from beeswax 10% addition.

  17. pHAST (pH-Driven Aptamer Switch for Thrombin) Catch-and-Release of Target Protein.

    Science.gov (United States)

    McConnell, E M; Bolzon, R; Mezin, P; Frahm, G; Johnston, M; DeRosa, M C

    2016-06-15

    A pH-driven DNA nanomachine based on the human α-thrombin binding aptamer was designed for the specific catch-and-release of human α-thrombin at neutral and acidic pH, respectively. In neutral conditions, the thrombin aptamer component of the nanomachine is exposed and exists in the G-quadruplex conformation required to bind to the target protein. At slightly acidic pH, the polyadenine tail of the nanomachine becomes partially protonated and A+(anti)•G(syn) mispairing results in a conformational change, causing the target protein to be released. Förster resonance energy transfer (FRET) was used to monitor conformational switching over multiple pH cycles. Electrophoretic mobility shift assay (EMSA) and fluorescence anisotropy were used to show pH dependent protein binding and release by the nanomachine. This approach could be applied generally to existing G-rich aptamers to develop novel biosensors, theranostics, and nanoswitches.

  18. Solid lipid particles for oral delivery of peptide and protein drugs I - Elucidating the release mechanism of lysozyme during lipolysis

    DEFF Research Database (Denmark)

    Christophersen, Philip Carsten B; Zhang, L.; Yang, M

    2013-01-01

    The mechanism of protein release from solid lipid particles was investigated by a new lipolysis model in a biorelevant medium containing both bile salts and phospholipids. Lysozyme, a model protein, was formulated into solid lipid particles using four different types of lipids, two triglycerides...... with different chain-length of fatty acyl groups i.e. trimyristin (TG14) and tristearin (TG18), and two lipid blends dominated by diglycerides and monoglycerides, respectively. The release of lysozyme from the solid lipid particles and the lipid hydrolysis process were assessed in the lipolysis model, while...... the drug release mechanism from solid lipid particles and can potentially be used in rational selection of lipid excipients for oral delivery of peptide/protein drugs....

  19. Two isoforms of eukaryotic phospholipase C in Paramecium affecting transport and release of GPI-anchored proteins in vivo.

    Science.gov (United States)

    Klöppel, Christine; Müller, Alexandra; Marker, Simone; Simon, Martin

    2009-10-01

    Surface proteins anchored by a glycosylphosphatidylinositol (GPI) residue in the cell membrane are widely distributed among eukaryotic cells. The GPI anchor is cleavable by a phospholipase C (PLC) leading to the release of such surface proteins, and this process is postulated to be essential in several systems. For higher eukaryotes, the responsible enzymes have not been characterized in any detail as yet. Here we characterize six PLCs in the ciliated protozoan, Paramecium, which, in terms of catalytic domains and architecture, all show characteristics of PLCs involved in signal transduction in higher eukaryotes. We show that some of these endogenous PLCs can release GPI-anchored surface proteins in vitro: using RNA(i) to reduce PLC expression results in the same effects as the application of PLC inhibitors. With two enzymes, PLC2 and PLC6, RNA(i) phenotypes show strong defects in release of GPI-anchored surface proteins in vivo. Moreover, these RNA(i) lines also show abnormal surface protein distribution, suggesting that GPI cleavage may influence trafficking of anchored proteins. As we find GFP fusion proteins in the cytosol and in the surface protein extracts, these PLCs obviously show unconventional translocation mechanisms. This is the first molecular data on endogenous Paramecium PLCs with the described properties affecting GPI anchors in vitro and in vivo.

  20. Controlled Release of Benzocaine from Monomer and Copolymer Carriers in Synthetic Gastro-intestinal Media

    Directory of Open Access Journals (Sweden)

    Houaria Merine

    2014-05-01

    Full Text Available New dosage forms able to control drug release in the gastro-intestinal media have been prepared and investigated in this paper. Two different type of medicinal agent bonding (MA, in our case Benzocaine (Bz, were chosen in order to examine drug release. i MA attached to ethylenic monomer (m,p-vinylbenzaldehyde, condensation reaction. ii The copolymer carrier (Cp is obtained by copolymerizing this monomer. These two carriers were well characterized by microanalysis, FTIR, DSC (Tg and GPC (Ip and the two fraction α and β were calculated from elemental analyses of Cp. The results showed good polydispersity and low average molecular weight. MA linked to an organic product by the azomethine function (C=N, hydrolytically sensitive, allowed controlled release of Bz, from the monomer carrier and from the bending Schiff bases groups. Theoretical and experimental analyses of controlled release of Bz kinetics from monomer and copolymer carriers were conducted for the case of contact with synthetic gastro-intestinal fluids at various pH (1,2; 6,0 and 8,0 at 37°C. The process was found to be controlled by the nature of media (heterogeneous, which involved the preliminary hydrolysis, and the drug (Bz diffusing out of structure of copolymer (Cp to the external aqueous media. The results obtained on the rate of delivery showed a clear difference between pH = 1,2 and pH = 6,0 and 8,0 based on: i The cation of p-aminoniumbenzoic acid (PABAH+ release at pH = 1,2 ii Bz release at pH = 6,0 and 8,0

  1. A whole blood in vitro cytokine release assay with aqueous monoclonal antibody presentation for the prediction of therapeutic protein induced cytokine release syndrome in humans.

    Science.gov (United States)

    Wolf, Babette; Morgan, Hannah; Krieg, Jennifer; Gani, Zaahira; Milicov, Adriana; Warncke, Max; Brennan, Frank; Jones, Stewart; Sims, Jennifer; Kiessling, Andrea

    2012-12-01

    The administration of several monoclonal antibodies (mAbs) to humans has been associated with acute adverse events characterized by clinically significant release of cytokines in the blood. The limited predictive value of toxicology species in this field has triggered intensive research to establish human in vitro assays using peripheral blood mononuclear cells or blood to predict cytokine release in humans. A thorough characterization of these assays is required to understand their predictive value for hazard identification and risk assessment in an optimal manner, and to highlight potential limitations of individual assay formats. We have characterized a whole human blood cytokine release assay with only minimal dilution by the test antibodies (95% v/v blood) in aqueous presentation format, an assay which has so far received less attention in the scientific world with respect to the evaluation of its suitability to predict cytokine release in humans. This format was compared with a human PBMC assay with immobilized mAbs presentation already well-characterized by others. Cytokine secretion into plasma or cell culture supernatants after 24h incubation with the test mAbs (anti-CD28 superagonist TGN1412-like material (TGN1412L), another anti-CD28 superagonistic mAb (ANC28.1), a T-cell depleting mAb (Orthoclone™), and a TGN1412 isotype-matched control (Tysabri™) not associated with clinically-relevant cytokine release) was detected by a multiplex assay based on electrochemiluminescent excitation. We provide proof that this whole blood assay is a suitable new method for hazard identification of safety-relevant cytokine release in the clinic based on its ability to detect the typical cytokine signatures found in humans for the tested mAbs and on a markedly lower assay background and cytokine release with the isotype-matched control mAb Tysabri™ - a clear advantage over the PBMC assay. Importantly, quantitative and qualitative differences in the relative cytokine

  2. 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.

  3. Controlled drug-release system based on pH-sensitive chloride-triggerable liposomes.

    Science.gov (United States)

    Wehunt, Mark P; Winschel, Christine A; Khan, Ali K; Guo, Tai L; Abdrakhmanova, Galya R; Sidorov, Vladimir

    2013-03-01

    New pH-sensitive lipids were synthesized and utilized in formulations of liposomes suitable for controlled drug release. These liposomes contain various amounts of NaCl in the internal aqueous compartments. The release of the drug model is triggered by an application of HCl cotransporter and exogenous physiologically relevant NaCl solution. HCl cotransporter allows an uptake of HCl by liposomes to the extent of their being proportional to the transmembrane Cl(-) gradient. Therefore, each set of liposomes undergoes internal acidification, which, ultimately, leads to the hydrolysis of the pH-sensitive lipids and content release at the desired time. The developed system releases the drug model in a stepwise fashion, with the release stages separated by periods of low activity. These liposomes were found to be insensitive to physiological concentrations of human serum albumin and to be nontoxic to cells at concentrations exceeding pharmacological relevance. These results render this new drug-release model potentially suitable for in vivo applications.

  4. Formulation and evaluation of dorzolamide hydrochloride-loaded nanoparticles as controlled release drug delivery system

    Directory of Open Access Journals (Sweden)

    Azza A Hasan

    2012-01-01

    Full Text Available This study aimed to prepare anti-glaucomatous dorzolamide hydrochloride-(Dorzo loaded nanoparticles as a controlled release system. Eudragit RS 100 (RS and/or RL 100 (RL were used in formulations by an opportunely adapted Quasi-emulsion solvent diffusion technique. The formulations were evaluated in terms of particle size, zeta potential, drug entrapment, and release profile. All formulations showed tiny particle size varying from 114 to 395 nm for RS and 65 to 277 nm for RL. Positive zeta potential was +19 to +32 mV for RS and +23 to +42 mV for RL formulations. It was demonstrated that increasing polymer concentration lead to increase the percentage of drug entrapped in all batches, to a certain extent (drug: polymer 1:4. Nanoparticles prepared using RL showed lower entrapment efficiency than RS. In contrast, increasing the stirring rate resulted in an increase in the percentage of Dorzo entrapped. A prolonged drug release was shown by all the formulations. Increasing the polymer concentration caused a decrease in the release rate. Moreover, it was evident that increasing RL content increased the amount of Dorzo released. Dorzo-loaded nanoparticles could represent promising drug ophthalmic carriers, due to small particle size, positive zeta potential, and sustained release profile; hence, expecting prolonged corneal contact time, more therapeutically efficient, decreased frequency of administration per day, and better patient compliance.

  5. Flavor release and perception of flavored whey protein gels: Perception is determined by texture rather than by release

    NARCIS (Netherlands)

    Weel, K.G.C.; Boelrijk, A.E.M.; Alting, A.C.; Mil, van P.J.J.M.; Burger, J.J.; Gruppen, H.; Voragen, A.G.J.; Smit, G.

    2002-01-01

    Five whey protein gels, with different gel hardnesses and waterholding capacities, were flavored with ethylbutyrate or diacetyl and evaluated by a 10-person panel to study the relation between the gel structure and the sensory perception, as well as the nosespace flavor concentration during eating.

  6. Flavor release and perception of flavored whey protein gels: Perception is determined by texture rather than by release

    NARCIS (Netherlands)

    Weel, K.G.C.; Boelrijk, A.E.M.; Alting, A.C.; Mil, van P.J.J.M.; Burger, J.J.; Gruppen, H.; Voragen, A.G.J.; Smit, G.

    2002-01-01

    Five whey protein gels, with different gel hardnesses and waterholding capacities, were flavored with ethylbutyrate or diacetyl and evaluated by a 10-person panel to study the relation between the gel structure and the sensory perception, as well as the nosespace flavor concentration during eating.

  7. Novel layered pesticide slow/controlled release materials--supramolecular structure and slow release property of glyphosate intercalated layered double hydroxides

    Institute of Scientific and Technical Information of China (English)

    MENG Jinhong; ZHANG Hui; David G. Evans; DUAN Xue

    2005-01-01

    Two different interlayer structured glyphosate (GLY) intercalated MgAl layered double hydroxides, as novel pesticide slow/controlled release materials, have been synthesized by co-precipitation method under various reaction pH values. The slow/controlled release properties have been tested in Na2CO3 aqueous solution. The release mechanism has been interpreted on the basis of the ion-exchange between the guest GLY anions in the lamellar host and in the release media, and the diffusion process of GLY anions in the interstice and interlayer of GLY intercalates, i.e. diffusion through the particles, is the rate-limiting step of GLY release process. The GLY intercalate assembled at lower pH, possessing higher interlayer gallery height and vertical monolayered arrangement of guest anions in the interlayer with larger packing density, exhibits better slow release property than that assembled at higher pH. The results reveal that the layered double hydroxides have potential application in the pesticide slow/controlled release area.

  8. Escitalopram versus paroxetine controlled release in major depressive disorder: a randomized trial

    Science.gov (United States)

    Kishi, Taro; Matsuda, Yuki; Matsunaga, Shinji; Moriwaki, Masatsugu; Otake, Yoichiro; Akamatsu, Kaku; Okochi, Tomo; Hirano, Shigeki; Funahashi, Toshihiko; Okuda, Momoko; Tabuse, Hideaki; Fujita, Kiyoshi; Iwata, Nakao

    2017-01-01

    Objective There are no direct comparisons between escitalopram and paroxetine controlled release in patients with major depressive disorder (MDD). Methods We conducted a 24-week, rater-masked, randomized trial of escitalopram (5–20 mg/day) versus paroxetine controlled release (12.5–50 mg/day) in patients with MDD (UMIN000011191). Patients with the diagnosis of moderate-to-severe MDD (a 17-item Hamilton Rating Scale for Depression [HAMD-17], with total score at baseline being ≥20) were recruited to participate in a parallel, randomized, controlled trial. The primary outcome for efficacy was an improvement in the 21-item HAMD (HAMD-21) total score at 24 weeks. The secondary outcomes were the response, remission, and discontinuation rates and the incidence of individual adverse events. Results A total of 88 patients with MDD (males, 61.4%; mean age, 40.8±13.4 years) were recruited. The discontinuation rate was 58.0% (escitalopram, 55.8%; paroxetine controlled release, 60.0%). Both escitalopram and paroxetine controlled-release treatment groups exhibited significant reduction in the HAMD-21 total score at 2, 4, 8, 12, and 24 weeks from the baseline. However, there were no significant differences in the HAMD-21 total score, response rate, remission rate, and discontinuation rate at any time point between the groups. In addition, there were no significant differences in the incidence of any individual adverse events (eg, nausea, vomiting, and somnolence) between the treatment groups. Conclusion Our results suggest that escitalopram and paroxetine controlled release had similar efficacy and safety profiles in patients with MDD. One of the primary limitations of this study is the small sample size. PMID:28123299

  9. Effects of Control Release Fertilizers on Nutrient Leaching, Palm Growth and Production Cost

    Directory of Open Access Journals (Sweden)

    Pushpa Soti

    2015-11-01

    Full Text Available Objective of this study was to evaluate the effect of different controlled release fertilizer technologies on nutrient leaching and plant growth parameters of two palm species, Chinese Fan (Livistona chinensis and Queen (Syagrus romanzoffiana. We compared Nutri-Pak (12-4-12 controlled release packet and Harrell’s (12-4-12 controlled release polymer coated urea against Atlantic (8-4-12 controlled release polymer coated urea, coated sulfate of potash, the most commonly used palm fertilizer in South Florida. Plants were grown in 25 cm (11 L pots under 70% shade, watered weekly, with pest and weed control done as required. Plant growth parameters: number of leaves, leaf length and width, and basal diameter, were measured every two months. Leachate was collected weekly after irrigation and a two-month composite sample was analyzed for nutrient concentrations. There was no difference in the growth parameters among the three fertilizers for Chinese Fan plants. However for Queen, Atlantic and Harrell’s had significantly thicker basal diameter than Nutri-Pak. Significant difference in the concentration of nutrients in the leachate was observed among the fertilizer types. Throughout the study period, Nutri-Pak had a lower concentration of nutrients in the leachate than Atlantic and Harrell’s. Our research indicates that Nutri-Pak control release fertilizer is comparable to other commercial fertilizers in Chinese Fan growth, but the larger Queen palms likely require an additional packet. Nutri-Pak fertilizer resulted in less nutrient leaching and could be a better environmental choice.

  10. Interaction of Fibrinogen and Muramidase-released Protein Promotes the Development of Streptococcus suis Meningitis

    Directory of Open Access Journals (Sweden)

    Junping eWang

    2015-09-01

    Full Text Available Muramidase-released protein (MRP is as an important virulence marker of Streptococcus suis (S. suis serotype 2. Our previous works have shown that MRP can bind human fibrinogen (hFg; however, the function of this interaction in S.suis meningitis is not known. In this study, we found that the deletion of mrp significantly impairs the hFg-mediated adherence and traversal ability of S. suis across human cerebral microvascular endothelial cells (hCMEC/D3. Measurement of the permeability to Lucifer yellow in vitro and Evans blue extravasation in vivo show that the MRP-hFg interaction significantly increases the permeability of the blood-brain barrier (BBB. In the mouse meningitis model, wild type S. suis caused higher bacterial loads in the brain and more severe histopathological signs of meningitis than the mrp mutant at day 3 post-infection. Western blot analysis and immunofluorescence observations reveal that the MRP-hFg interaction can destroy the cell adherens junction protein p120-catenin of hCMEC/D3. These results indicate that the MRP-hFg interaction is important in the development of S. suis meningitis.

  11. Wireless platform for controlled nitric oxide releasing optical fibers for mediating biological response to implanted devices.

    Science.gov (United States)

    Starrett, Michael A; Nielsen, Matthew; Smeenge, David M; Romanowicz, Genevieve E; Frost, Megan C

    2012-12-01

    Despite the documented potential to leverage nitric oxide generation to improve in vivo performance of implanted devices, a key limitation to current NO releasing materials tested thus far is that there has not been a means to modulate the level of NO release after it has been initiated. We report the fabrication of a wireless platform that uses light to release NO from a polymethylmethacrylate (PMMA) optical fiber coated with an S-nitroso-N-acetylpenicillamine derivatized polydimethylsiloxane (SNAP-PDMS). We demonstrate that a VAOL-5GSBY4 LED (λ(dominant)=460 nm) can be used as a dynamic trigger to vary the level of NO released from 500 μm diameter coated PMMA. The ability to generate programmable sequences of NO flux from the surface of these coated fibers offers precise spatial and temporal control over NO release and provides a platform to begin the systematic study of in vivo physiological response to implanted devices. NO surface fluxes up to 3.88 ± 0.57 × 10(-10)mol cm(-2)min(-1) were achieved with -100 μm thick coatings on the fibers and NO flux was pulsed, ramped and held steady using the wireless platform developed. We demonstrate the NO release is linearly proportional to the drive current applied to the LED (and therefore level of light produced from the LED). This system allow the surface flux of NO from the fibers to be continuously changed, providing a means to determine the level and duration of NO needed to mediate physiological response to blood contacting and subcutaneous implants and will ultimately lead to the intelligent design of NO releasing materials tailored to specific patterns of NO release needed to achieve reliable in vivo performance for intravascular and subcutaneous sensors and potentially for a wide variety of other implanted biomedical devices.

  12. Effects of Controlled Release Fertilizer on the Post-Production Performance of Impatiens Wallerana

    Science.gov (United States)

    Controlled release fertilizers (CRF) in production systems have been known to reduce environmental contamination. However, there is a lot to be explored as per its use in bedding plant production. Bedding plant growers have not adapted CRF use because there is little information about its use and ...

  13. Longevity of controlled release fertilizer influences the growth of bedding Impatiens

    Science.gov (United States)

    Controlled-release fertilizers (CRF) have not been extensively used in floriculture production, perhaps due to lack of grower experience and research-based information with their use in herbaceous plant production. Any information about the correct use of CRF should increase growers’ confidence in ...

  14. Substrates and controlled-release fertilizations on the quality of eucalyptus cuttings

    Directory of Open Access Journals (Sweden)

    Richardson B. G. da Silva

    2014-11-01

    Full Text Available To produce cuttings with quality, the most appropriate nutritional management strategies should be sought to reduce wastage of fertilizer, while accounting for the characteristics of each substrate. This study evaluated the effect of substrates and doses of controlled-release fertilizer on the quality of Eucalyptus grandis Hill ex Maiden x Eucalyptus urophylla S. T. Blake cuttings. The substrates consisted of several mixtures: vermiculite+carbonized rice chaff+coconut fibre (1:1:1; vermiculite+coconut fibre (1:1; and vermiculite+carbonized rice chaff (1:1. These mixtures were added to 2, 4, 6 and 8 kg of controlled-release fertilizer per cubic meter of substrate. The substrates that do not support root development and have lower water retention, independently of the dose of controlled-release fertilizer, reduce the quality of the root system. For substrates with proper values of water retention, such as vermiculite+coconut fibre (1:1 and vermiculite+carbonised rice chaff+coconut fibre (1:1:1, the utilization of dose 2 kg of controlled-release fertilizer to each cubic meter is enough to promote cuttings with greater quality of the root systems and proper heights and stem diameters.

  15. 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

  16. Evaluation of Dosing Guidelines for Use of Controlled-Release Codeine in Chronic Noncancer Plan

    Directory of Open Access Journals (Sweden)

    Alan Russell

    2003-01-01

    Full Text Available OBJECTIVE: The clinical utility of guidelines for conversion of patients from a combination analgesic preparation of acetaminophen 300 mg plus codeine 30 mg every 4 h to 6h as needed to scheduled controlled-release (CR codeine every 12 h was evaluated.

  17. Supramolecular Controlled Cargo Release via Near Infrared Tunable Cucurbit[7]uril-Gold Nanostars.

    Science.gov (United States)

    Han, Yanwei; Yang, Xiran; Liu, Yingzhu; Ai, Qiushuang; Liu, Simin; Sun, Chunyan; Liang, Feng

    2016-02-26

    The near infrared (NIR) absorption and average particle size of gold nanostars (GNSs) can be precisely controlled by varying the molar ratios of cucurbit[7]urils (CB[7]) and GNSs in aqueous solution. GNSs modified with CB[7] achieved high cargo loading with thermally activated release upon the NIR laser irradiation.

  18. EVALUATION OF BIOREMEDIATION STRATEGIES OF A CONTROLLED OIL RELEASE IN A WETLAND

    Science.gov (United States)

    A controlled petroleum release was conducted to evaluate bioremediation in a wetland near Houston, Texas. The 140-day study was conducted using a randomized, complete block design to test three treatments with six replicates per treatment. The three treatment strategies were in...

  19. Biological control of tropical soda apple (Solanaceae) in Florida: Post-release evaluation

    Science.gov (United States)

    The leaf feeding beetle Gratiana boliviana Spaeth (Coleoptera: Chrysomelidae) was released as a biological control agent against tropical soda apple (TSA) (Solanum viarum Dunal (Solanaceae)) in Sumter County, FL in 2006. Evaluation of beetle feeding damage to TSA plants and changes in the beetle po...

  20. Series elasticity of the human triceps surae muscle : Measurement by controlled-release vs. resonance methods.

    NARCIS (Netherlands)

    Hof, AL; Boom, H; Robinson, C; Rutten, W; Neuman, M; Wijkstra, H

    1997-01-01

    With a newly developed Controlled-Release Ergometer the complete characteristic of the series elastic component can be measured in human muscles. Previous estimates were based on the resonance method: muscle elasticity was assessed from the resonance frequency of the muscle elasticity connected to a

  1. 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

  2. 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...

  3. Design Project on Controlled-Release Drug Delivery Devices: Implementation, Management, and Learning Experiences

    Science.gov (United States)

    Xu, Qingxing; Liang, Youyun; Tong, Yen Wah; Wang, Chi-Hwa

    2010-01-01

    A design project that focuses on the subject of controlled-release drug delivery devices is presented for use in an undergraduate course on mass transfer. The purpose of the project is to introduce students to the various technologies used in the fabrication of drug delivery systems and provide a practical design exercise for understanding the…

  4. Controlled release fungicide, soil amendments and biofumigation effects on cotton root rot suppression

    Science.gov (United States)

    The cotton root rot pathogen (Phymatotrichopsis ominora) causes major losses in cotton produced in the Southwest. Granular controlled release formulations (CRF) of the fungicide, Propiconazole, developed to be soil applied at planting were studied at 1.0 and 3.0 lb a.i./ac. applications and with tw...

  5. Convex quadratic programming relaxations for parallel machine scheduling with controllable processing times subject to release times

    Institute of Scientific and Technical Information of China (English)

    ZHANG Feng; CHEN Feng; TANG Guochun

    2004-01-01

    Scheduling unrelated parallel machines with controllable processing times subject to release times is investigated. Based on the convex quadratic programming relaxation and the randomized rounding strategy, a 2-approximation algorithm is obtained for a special case with the all-or-none property and then a 3-approximation algorithm is presented for general problem.

  6. 78 FR 56541 - Concept Release on Risk Controls and System Safeguards for Automated Trading Environments

    Science.gov (United States)

    2013-09-12

    ... September 12, 2013 Part IV Commodity Futures Trading Commission 17 CFR Chapter I Concept Release on Risk Controls and System Safeguards for Automated Trading Environments; Proposed Rule #0;#0;Federal Register / Vol. 78 , No. 177 / Thursday, September 12, 2013 / Proposed Rules#0;#0; ] COMMODITY FUTURES...

  7. Pharmacokinetics and pharmacodynamics of controlled release insulin loaded PLGA microcapsules using dry powder inhaler in diabetic rats.

    Science.gov (United States)

    Hamishehkar, Hamed; Emami, Jaber; Najafabadi, Abdolhossien Rouholamini; Gilani, Kambiz; Minaiyan, Mohsen; Hassanzadeh, Kambiz; Mahdavi, Hamid; Koohsoltani, Maryam; Nokhodchi, Ali

    2010-03-01

    The pulmonary route is an alternative route of administration for the systemic delivery of peptide and proteins with short-half lives. A long-acting formulation of insulin was prepared by encapsulation of protein into respirable, biodegradable microcapsules prepared by an oil in oil emulsification/solvent evaporation method. Insulin-loaded PLGA microcapsules prepared as a dry powder inhaler formulation were administered via the pulmonary route to diabetic rats and serum insulin and glucose concentrations were monitored. Control treatments consisted of respirable spray-dried insulin (RSDI) powder administered by intratracheal insufflation, insulin-loaded PLGA microcapsules and NPH (long-acting) insulin administered by subcutaneous (SC) administration. Pharmacokinetic analysis demonstrated that insulin administered in PLGA microcapsules illustrated a sustained release profile which resulted in a longer mean residence time, 4 and 5 fold longer than those after pulmonary administration of RSDI and SC injection of NPH insulin, respectively. Accordingly, the hypoglycemic profile followed a stable and sustained pattern which remained constant between 10 and 48 h. Results of the in vitro experiments were in good agreement with those of in vivo studies. Bronchoalveolar lavage fluid analysis indicated that microcapsules administration did not increase the activities of lactate dehydrogenase and total protein. However, histological examination of the lung tissue indicated a minor but detectable effect on the normal physiology of the rat lung. These findings suggest that the encapsulation of peptides and proteins into PLGA microcapsules technique could be a promising controlled delivery system for pulmonary administration.

  8. Controlled release of verapamil hydrochloride from waxy microparticles prepared by spray congealing.

    Science.gov (United States)

    Passerini, Nadia; Perissutti, Beatrice; Albertini, Beatrice; Voinovich, Dario; Moneghini, Mariarosa; Rodriguez, Lorenzo

    2003-03-01

    In this work, the potential of waxes for preparing with the ultrasonic spray congealing technique microparticles for controlling the in vitro release of verapamil HCl was investigated. The first part of the study encompassed the optimisation of the formulation to achieve an efficient drug incorporation together with a satisfactory in vitro drug release rate. In particular, microcrystalline wax, stearyl alcohol and mixtures of the two were used. Also a surfactant (soya lecithin) was added to the formulations. After the particle size analysis, the characterisation of the microparticles involved the study of the solid state of drug and carriers in the systems (DSC, HSM and XRD) and the morphological and chemical analyses of the microparticle surface (SEM and XPS). Finally, the drug release mechanism from these devices was evaluated using the statistical moment analysis. The results of this study show that by selecting the type and the amount of