WorldWideScience

Sample records for magnetic microparticle carrier

  1. Magnetic microparticles post-synthetically coated by hyaluronic acid as an enhanced carrier for microfluidic bioanalysis

    International Nuclear Information System (INIS)

    Holubova, Lucie; Knotek, Petr; Palarcik, Jiri; Cadkova, Michaela; Belina, Petr; Vlcek, Milan; Korecka, Lucie; Bilkova, Zuzana

    2014-01-01

    Iron oxide based particles functionalized by bioactive molecules have been utilized extensively in biotechnology and biomedicine. Despite their already proven advantages, instability under changing reaction conditions, non-specific sorption of biomolecules on the particles' surfaces, and iron oxide leakage from the naked particles can greatly limit their application. As confirmed many times, surface treatment with an appropriate stabilizer helps to minimize these disadvantages. In this work, we describe enhanced post-synthetic surface modification of superparamagnetic microparticles varying in materials and size using hyaluronic acid (HA) in various chain lengths. Scanning electron microscopy, atomic force microscopy, phase analysis light scattering and laser diffraction are the methods used for characterization of HA-coated particles. The zeta potential and thickness of HA-layer of HA-coated Dynabeads M270 Amine were − 50 mV and 85 nm, respectively, and of HA-coated p(GMA-MOEAA)-NH 2 were − 38 mV and 140 nm, respectively. The electrochemical analysis confirmed the zero leakage of magnetic material and no reactivity of particles with hydrogen peroxide. The rate of non-specific sorption of bovine serum albumin was reduced up to 50% of the naked ones. The coating efficiency and suitability of biopolymer-based microparticles for magnetically active microfluidic devices were confirmed. - Highlights: • Post-synthetic surface modification of magnetic microparticles by hyaluronic acid • Hyaluronic acid — polymer of unique physicochemical and biological characteristics • Panel of particle characterization methods was introduced. • HA-coated microparticles gain characteristics suited for microfluidic bioanalysis

  2. Carboxyl-functionalized magnetic microparticle carrier for isolation and identification of DNA in dairy products

    Czech Academy of Sciences Publication Activity Database

    Horák, Daniel; Rittich, B.; Španová, A.

    2007-01-01

    Roč. 311, č. 1 (2007), s. 249-254 ISSN 0304-8853 R&D Projects: GA ČR GA525/05/0311 Institutional research plan: CEZ:AV0Z40500505 Keywords : magnetic particles * DNA * magnetite Subject RIV: GM - Food Processing Impact factor: 1.704, year: 2007

  3. Carboxyl-functionalized magnetic microparticle carrier for isolation and identification of DNA in dairy products

    International Nuclear Information System (INIS)

    Horak, Daniel; Rittich, Bohuslav; Spanova, Alena

    2007-01-01

    Magnetite nanoparticles about 14nm in diameter were obtained by chemical coprecipitation of Fe(II) and Fe(III) salts with aqueous ammonia in the presence of poly(ethylene glycol) (PEG). Magnetic poly(glycidyl methacrylate) (PGMA) microspheres about 1μm in diameter were prepared by dispersion polymerization of GMA in aqueous ethanol in the presence of PEG-coated magnetite nanoparticles. The microspheres were hydrolyzed and carboxyl groups introduced by oxidation with KMnO 4 . The particles reversibly bound bacterial DNA of Bifidobacterium and Lactobacillus genera in the presence of high concentrations of PEG 6000 and sodium chloride from crude cell lysates of various dairy products (butter milk, cheese, yoghurt, probiotic tablets) or from cell lyophilisates. The presence of Bifidobacterium and Lactobacillus DNA in samples was confirmed by PCR amplification

  4. Carboxyl-functionalized magnetic microparticle carrier for isolation and identification of DNA in dairy products

    Energy Technology Data Exchange (ETDEWEB)

    Horak, Daniel [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovskeho Sq. 2, 162 06 Prague 6 (Czech Republic)]. E-mail: horak@imc.cas.cz; Rittich, Bohuslav [Masaryk University Brno, Tvrdeho 14, 602 00 Brno (Czech Republic)]. E-mail: rittich@sci.muni.cz; Spanova, Alena [Masaryk University Brno, Tvrdeho 14, 602 00 Brno (Czech Republic)]. E-mail: spanova@sci.muni.cz

    2007-04-15

    Magnetite nanoparticles about 14nm in diameter were obtained by chemical coprecipitation of Fe(II) and Fe(III) salts with aqueous ammonia in the presence of poly(ethylene glycol) (PEG). Magnetic poly(glycidyl methacrylate) (PGMA) microspheres about 1{mu}m in diameter were prepared by dispersion polymerization of GMA in aqueous ethanol in the presence of PEG-coated magnetite nanoparticles. The microspheres were hydrolyzed and carboxyl groups introduced by oxidation with KMnO{sub 4}. The particles reversibly bound bacterial DNA of Bifidobacterium and Lactobacillus genera in the presence of high concentrations of PEG 6000 and sodium chloride from crude cell lysates of various dairy products (butter milk, cheese, yoghurt, probiotic tablets) or from cell lyophilisates. The presence of Bifidobacterium and Lactobacillus DNA in samples was confirmed by PCR amplification.

  5. Microparticle-initiated losses in magnetically insulated transmission lines

    International Nuclear Information System (INIS)

    Gray, E.W.; Stinnett, R.W.

    1986-01-01

    The author's discuss the effects of high and hypervelocity microparticles in magnetically-insulated transmission lines (MITLs) and how they may be a possible source for ion production near the anode in early stages of the voltage pulse, and current carriers during and after the power pulse, resulting in power flow losses. Early losses in the voltage pulse, due to microparticles, are estimated to be approximately 0.3 mA/cm/sup 2/. Blistering of the electrode surface, thought to be due to H/sup -/ bombardment, was also observed and appears to be consistent with losses due to negative ions previously reported by one of the authors

  6. Herbal carrier-based floating microparticles of diltiazem ...

    African Journals Online (AJOL)

    Purpose: To formulate and characterize a gastroretentive floating drug delivery system for diltiazem hydrochloride using psyllium husk and sodium alginate as natural herbal carriers to improve the therapeutic effect of the drug in cardiac patients. Methods: Floating microparticles containing diltiazem hydrochloride were ...

  7. Energy losses in magnetically insulated transmission lines due to microparticles

    International Nuclear Information System (INIS)

    Gray, E.W.; Stinnett, R.W.

    1987-01-01

    We discuss the effects of high-velocity and hypervelocity microparticles in the magnetically insulated transmission lines of multiterawatt accelerators used for particle beam fusion and radiation effects simulation. These microparticles may be a possible source for plasma production near the anode and cathode in early stages of the voltage pulse, and current carriers during and after the power pulse, resulting in power flow losses. Losses in the current pulse, due to microparticles, are estimated to be approximately 12 mA/cm 2 (0.3 kA) as a lower limit, and --0.3 A/cm 2 (7.2 kA) for microparticle initiated, anode plasma positive ion transport. We have calculated the velocities reached by these microparticles and the effects on them of Van der Waals forces. Field emission from the particles and their effects on cathode and anode plasma formation have been examined. Particle collision with the electrodes is also examined in terms of plasma production, as in the electron deposition in the particles in transit across the anode-cathode gap. Blistering of the electrode surface, thought to be due to H - bombardment was also observed and appears to be consistent with losses due to negative ions previously reported by J. P. VanDevender, R. W. Stinnett, and R. J. Anderson [App. Phys. Lett. 38, 229 (1981)

  8. Harvesting microalgae with microwave synthesized magnetic microparticles

    Czech Academy of Sciences Publication Activity Database

    Procházková, G.; Šafařík, Ivo; Brányik, T.

    2013-01-01

    Roč. 130, FEB (2013), s. 472-477 ISSN 0960-8524 R&D Projects: GA MŠk LH12190 Institutional support: RVO:67179843 Keywords : harvesting microalgae * iron oxide magnetic microparticles * non-covalent interactions * microwave treatment * cell demagnetization Subject RIV: EI - Biotechnology ; Bionics Impact factor: 5.039, year: 2013

  9. Investigation of strain-induced magnetization change in ferromagnetic microparticles

    International Nuclear Information System (INIS)

    Chuklanov, A P; Nurgazizov, N I; Bizyaev, D A; Khanipov, T F; Bukharaev, A A; Yu Petukhov, V; Chirkov, V V; Gumarov, G G

    2016-01-01

    This work is devoted to investigation of magnetoelastic strain effect on the ferromagnetic microparticles of permalloy. An original method of sample fabrication with compressed microparticles is proposed. Magnetic force microscopy and magneto-optical Kerr experiments were carried out with unstrained and compressed microparticles. The domain walls transformation in compressed microparticles is in good agreement with numerical calculations. Hard axis of magnetization was observed on the compressed sample. (paper)

  10. Synthesis and characterization of robust magnetic carriers for bioprocess applications

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, Willian, E-mail: willkopp@gmail.com [Federal University of São Carlos-UFSCar, Graduate Program in Chemical Engineering, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); Silva, Felipe A., E-mail: eq.felipe.silva@gmail.com [Federal University of São Carlos-UFSCar, Graduate Program in Chemical Engineering, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); Lima, Lionete N., E-mail: lionetenunes@yahoo.com.br [Federal University of São Carlos-UFSCar, Graduate Program in Chemical Engineering, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); Masunaga, Sueli H., E-mail: sueli.masunaga@gmail.com [Department of Physics, Montana State University-MSU, 173840, Bozeman, MT 59717-3840 (United States); Tardioli, Paulo W., E-mail: pwtardioli@ufscar.br [Department of Chemical Engineering, Federal University of São Carlos-UFSCar, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); Giordano, Roberto C., E-mail: roberto@ufscar.br [Department of Chemical Engineering, Federal University of São Carlos-UFSCar, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); Araújo-Moreira, Fernando M., E-mail: faraujo@df.ufscar.br [Department of Physics, Federal University of São Carlos-UFSCar, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); and others

    2015-03-15

    Highlights: • Silica magnetic microparticles were synthesized for applications in bioprocesses. • The process to produce magnetic microparticles is inexpensive and easily scalable. • Microparticles with very high saturation magnetization were obtained. • The structure of the silica magnetic microparticles could be controlled. - Abstract: Magnetic carriers are an effective option to withdraw selected target molecules from complex mixtures or to immobilize enzymes. This paper describes the synthesis of robust silica magnetic microparticles (SMMps), particularly designed for applications in bioprocesses. SMMps were synthesized in a micro-emulsion, using sodium silicate as the silica source and superparamagnetic iron oxide nanoparticles as the magnetic core. Thermally resistant particles, with high and accessible surface area, narrow particle size distribution, high saturation magnetization, and with superparamagnetic properties were obtained. Several reaction conditions were tested, yielding materials with saturation magnetization between 45 and 63 emu g{sup −1}, particle size between 2 and 200 μm and average diameter between 11.2 and 15.9 μm, surface area between 49 and 103 m{sup 2} g{sup −1} and pore diameter between 2 and 60 nm. The performance of SMMps in a bioprocess was evaluated by the immobilization of Pseudomonas fluorescens lipase on to octyl modified SMMp, the biocatalyst obtained was used in the production of butyl butyrate with good results.

  11. Use of protein containing magnetic microparticles in radioassays

    International Nuclear Information System (INIS)

    Ithakissios, D.S.; Kubiatowicz, D.O.

    1977-01-01

    We describe a radioassay method that involves the use of magnetic protein microparticles composed of a water-insoluble protein matrix containing magnetically responsive material. We define two different types of particles according to the mechanism of action: The substrate is sorbed nonspecifically by the protein matrix of the particle or by a second substance such as charcoal or ion-exchange resin incorporated within the protein matrix of the particle. These particles are useful for separating free from bound substrate. Examples of these are albumin magnetic microparticles for use in a total thyroxine radioassay and triiodothyronine uptake test, or albumin magnetic microparticles containing charcoal for use in a vitamin B 12 radioassay. The substrate is sorbed specifically by a binding protein incorporated within the matrix of the particles. The binding protein can include antibodies or other specific nonimmune proteins. Particles of this type are useful in solid-phase radioassays. These particles are exemplified by albumin magnetic microparticles containing sockeye salmon serum, used in a solid-phase B 12 radioassay. We discuss the methods for the preparation of both types of magnetic microparticles and their use in radioassays. We describe a unique inexpensive magnetic separation rack, which provides simple, fast, and reproducible separation of the magnetic microparticles from their suspending medium during the assay

  12. Synchronous ultrasonic Doppler imaging of magnetic microparticles in biological tissues

    Energy Technology Data Exchange (ETDEWEB)

    Pyshnyi, Michael Ph. [Institute of Biochemical Physics, Russian Academy of Sciences, Kosygin St. 4, Moscow 119991 (Russian Federation); Kuznetsov, Oleg A. [Institute of Biochemical Physics, Russian Academy of Sciences, Kosygin St. 4, Moscow 119991 (Russian Federation)], E-mail: kuznetsov_oa@yahoo.com; Pyshnaya, Svetlana V.; Nechitailo, Galina S.; Kuznetsov, Anatoly A. [Institute of Biochemical Physics, Russian Academy of Sciences, Kosygin St. 4, Moscow 119991 (Russian Federation)

    2009-05-15

    We considered applicability of acoustic imaging technology for the detection of magnetic microparticles and nanoparticles inside soft biological tissues. Such particles are widely used for magnetically targeted drug delivery and magnetic hyperthermia. We developed a new method of ultrasonic synchronous tissue Doppler imaging with magnetic modulation for in vitro and in vivo detection and visualization of magnetic ultradisperse objects in soft tissues. Prototype hardware with appropriate software was produced and the method was successfully tested on magnetic microparticles injected into an excised pig liver.

  13. Synchronous ultrasonic Doppler imaging of magnetic microparticles in biological tissues

    International Nuclear Information System (INIS)

    Pyshnyi, Michael Ph.; Kuznetsov, Oleg A.; Pyshnaya, Svetlana V.; Nechitailo, Galina S.; Kuznetsov, Anatoly A.

    2009-01-01

    We considered applicability of acoustic imaging technology for the detection of magnetic microparticles and nanoparticles inside soft biological tissues. Such particles are widely used for magnetically targeted drug delivery and magnetic hyperthermia. We developed a new method of ultrasonic synchronous tissue Doppler imaging with magnetic modulation for in vitro and in vivo detection and visualization of magnetic ultradisperse objects in soft tissues. Prototype hardware with appropriate software was produced and the method was successfully tested on magnetic microparticles injected into an excised pig liver.

  14. Novel cryomilled physically cross-linked biodegradable hydrogel microparticles as carriers for inhalation therapy.

    Science.gov (United States)

    El-Sherbiny, I M; Smyth, H D C

    2010-01-01

    In this study, novel biodegradable physically cross-linked hydrogel microparticles were developed and evaluated in-vitro as potential carriers for inhalation therapy. These hydrogel microparticles were prepared to be respirable (desired aerodynamic size) when dry and also designed to avoid the macrophage uptake (attain large swollen size once deposited in lung). The swellable microparticles, prepared using cryomilling, were based on Pluronic® F-108 in combination with PEG grafted onto both chitosan (Cs) and its N-phthaloyl derivative (NPHCs). Polymers synthesized in the study were characterized using EA, FTIR, 2D-XRD and DSC. Morphology, particle size, density, biodegradation and moisture content of the microparticles were quantified. Swelling characteristics for both drug-free and drug-loaded microparticles showed excellent size increases (between 700-1300%) and the release profiles indicated sustained release could be achieved for up to 20 days. The respirable microparticles showed drug loading efficiency up to 92%. The enzymatic degradation of developed microparticles started within the first hour and only ∼10% weights were remaining after 10 days. In conclusion, these respirable microparticles demonstrated promising in-vitro performance for potential sustained release vectors in pulmonary drug delivery.

  15. Herbal carrier-based floating microparticles of diltiazem ...

    African Journals Online (AJOL)

    hydrochloride using psyllium husk and sodium alginate as natural herbal carriers to improve the ... Keywords: Diltiazem, Cardiac disease, Psyllium husk, Sodium alginate, Microsphere, ..... Barkai A, Pathak YV, Benita S. Polyacrylate (Eudragit.

  16. Magnetic nano- and microparticles in biotechnology

    Czech Academy of Sciences Publication Activity Database

    Šafařík, Ivo; Šafaříková, Miroslava

    2009-01-01

    Roč. 63, - (2009), s. 497-505 ISSN 0366-6352 R&D Projects: GA MPO 2A-1TP1/094; GA MŠk(CZ) OC 157 Institutional research plan: CEZ:AV0Z60870520 Keywords : magnetic particles * smart material Subject RIV: EI - Biotechnology ; Bionics Impact factor: 0.791, year: 2009

  17. Multifunctional magnetic nano/microparticles for bioapplications

    Czech Academy of Sciences Publication Activity Database

    Horák, Daniel; Babič, Michal; Jendelová, Pavla; Herynek, V.

    2010-01-01

    Roč. 26, č. 2 (2010), s. 38 ISSN 0233-7657. [Bridges in Life Sciences, Annual Scientific Meeting Regional Cooperation for Health, Science and Technology /5./. 09.04.2010-11.04.2010, Lviv] R&D Projects: GA MŠk 2B06053 Institutional research plan: CEZ:AV0Z40500505 Keywords : magnetic * nano particle * microsphere Subject RIV: EE - Microbiology, Virology

  18. On-chip bio-analyte detection utilizing the velocity of magnetic microparticles in a fluid

    KAUST Repository

    Giouroudi, Ioanna; van den Driesche, Sander; Kosel, Jü rgen; Grössinger, Roland; Vellekoop, Michael J.

    2011-01-01

    change when analyte is attached to their surface via antibody–antigen binding. When the magnetic microparticles are attracted by a magnetic field within a microfluidic channel their velocity depends on the presence of analyte. Specifically, their velocity

  19. Microparticles

    African Journals Online (AJOL)

    (DOAJ), African Journal Online, Bioline International, Open-J-Gate and Pharmacy ... Polymeric drug delivery systems ... carrier systems based on available literature [10- .... the formulation were close, but the polydispersity .... significantly difference (p < 0.05) from the ... Pacheco PD, Manrique JY, Martinez F. Thermodynamic.

  20. PEGylation of magnetic poly(glycidyl methacrylate) microparticles for microfluidic bioassays

    International Nuclear Information System (INIS)

    Kucerova, Jana; Svobodova, Zuzana; Knotek, Petr; Palarcik, Jiri; Vlcek, Milan; Kincl, Miloslav; Horak, Daniel; Autebert, Julien; Viovy, Jean-Louis; Bilkova, Zuzana

    2014-01-01

    In this study, magnetic poly(glycidyl methacrylate) microparticles containing carboxyl groups (PGMA-COOH) were coated using highly hydrophilic polymer poly(ethylene glycol) (PEG). PEG was used to reduce nonspecific interactions with proteins and cells while decreasing adhesion of particles to the walls of a microfluidic devices from poly(dimethylsiloxane) (PDMS) and cyclic olefin copolymer (COC). Zeta potential measurement, infrared spectroscopy, scanning electron microscopy, anti-PEG ELISA assay, and bioaffinity interactions between biotin and streptavidin-HRP successfully proved the presence of PEG on the surface of microspheres. Both neat and PEGylated microspheres were then incubated with the inert protein bovine serum albumin or cells to evaluate the rate of nonspecific adsorption (NSA). PEG with Mr of 30,000 Da was responsible for 45% reduction in NSA of proteins and 74% for cells compared to neat particles. The microspheres' behavior in PDMS and COC microchannels was then evaluated. Aggregation and adhesion of PEGylated microspheres significantly decreased compared to neat particles. Finally, the model enzyme horseradish peroxidase was immobilized on the microspheres through the heterobifunctional PEG chain. The possibility for subsequent covalent coupling of the ligand of interest was confirmed. Such PEGylated microparticles can be efficiently used in PDMS microchips as a carrier for bioaffinity separation or of enzyme for catalysis. - Highlights: • Magnetic polymer microspheres with highly hydrophilic PEG coating were prepared. • PEG reduced microsphere adhesion in microchannels versus neat particles. • Suitability of methods for detecting PEG on magnetic microspheres was investigated. • PEG on microsphere surfaces decreased nonspecific adsorption of proteins and cells

  1. PEGylation of magnetic poly(glycidyl methacrylate) microparticles for microfluidic bioassays

    Energy Technology Data Exchange (ETDEWEB)

    Kucerova, Jana; Svobodova, Zuzana [Department of Biological and Biochemical Sciences, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic); Knotek, Petr [Joint Laboratory of Solid State Chemistry of IMC and University of Pardubice, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic); Palarcik, Jiri [Institute of Environmental and Chemical Engineering, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic); Vlcek, Milan; Kincl, Miloslav; Horak, Daniel [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 16206 Prague 6 (Czech Republic); Autebert, Julien; Viovy, Jean-Louis [Macromolecules and Microsystems in Biology and Medicine, Institute Curie, UMR 168, 26 Rue d' Ulm, 75005 Paris (France); Bilkova, Zuzana, E-mail: zuzana.bilkova@upce.cz [Department of Biological and Biochemical Sciences, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic)

    2014-07-01

    In this study, magnetic poly(glycidyl methacrylate) microparticles containing carboxyl groups (PGMA-COOH) were coated using highly hydrophilic polymer poly(ethylene glycol) (PEG). PEG was used to reduce nonspecific interactions with proteins and cells while decreasing adhesion of particles to the walls of a microfluidic devices from poly(dimethylsiloxane) (PDMS) and cyclic olefin copolymer (COC). Zeta potential measurement, infrared spectroscopy, scanning electron microscopy, anti-PEG ELISA assay, and bioaffinity interactions between biotin and streptavidin-HRP successfully proved the presence of PEG on the surface of microspheres. Both neat and PEGylated microspheres were then incubated with the inert protein bovine serum albumin or cells to evaluate the rate of nonspecific adsorption (NSA). PEG with Mr of 30,000 Da was responsible for 45% reduction in NSA of proteins and 74% for cells compared to neat particles. The microspheres' behavior in PDMS and COC microchannels was then evaluated. Aggregation and adhesion of PEGylated microspheres significantly decreased compared to neat particles. Finally, the model enzyme horseradish peroxidase was immobilized on the microspheres through the heterobifunctional PEG chain. The possibility for subsequent covalent coupling of the ligand of interest was confirmed. Such PEGylated microparticles can be efficiently used in PDMS microchips as a carrier for bioaffinity separation or of enzyme for catalysis. - Highlights: • Magnetic polymer microspheres with highly hydrophilic PEG coating were prepared. • PEG reduced microsphere adhesion in microchannels versus neat particles. • Suitability of methods for detecting PEG on magnetic microspheres was investigated. • PEG on microsphere surfaces decreased nonspecific adsorption of proteins and cells.

  2. Biosensing utilizing the motion of magnetic microparticles in a microfluidic system

    KAUST Repository

    Giouroudi, Ioanna

    2010-10-23

    The study for the design of a compact and inexpensive biosensing device, which can be operated either by primary care personnel or by patients as opposed to skilled operators, is presented. The main parts of the proposed device are a microfluidic channel, permanent magnets and functionalized magnetic microparticles. The innovative aspect of the proposed biosensing method is that it utilizes the volumetric increase of magnetic microparticles when analyte binds to their surface. Their velocity decreases drastically when they are accelerated by an externally applied magnetic force within a microfluidic channel. This effect is utilized to detect the presence of analyte e.g. microbes. Analytical calculations showed that a decrease in velocity of approximately 23% can be achieved due to the volumetric change of a magnetic microparticle of View the MathML source1μm diameter when HIV virions of approximately View the MathML source0,135μm are bound to its surface and by keeping its magnetic properties the same. Preliminary experiments were carried out utilizing superparamagnetic microparticles coated with streptavidin and polystyrene microparticles coated with biotin.

  3. Biosensing utilizing the motion of magnetic microparticles in a microfluidic system

    KAUST Repository

    Giouroudi, Ioanna; Driesche, Sander van den; Kosel, Jü rgen

    2010-01-01

    of approximately 23% can be achieved due to the volumetric change of a magnetic microparticle of View the MathML source1μm diameter when HIV virions of approximately View the MathML source0,135μm are bound to its surface and by keeping its magnetic properties

  4. On-chip bio-analyte detection utilizing the velocity of magnetic microparticles in a fluid

    KAUST Repository

    Giouroudi, Ioanna

    2011-03-22

    A biosensing principle utilizing the motion of suspended magnetic microparticles in a microfluidic system is presented. The system utilizes the innovative concept of the velocity dependence of magnetic microparticles (MPs) due to their volumetric change when analyte is attached to their surface via antibody–antigen binding. When the magnetic microparticles are attracted by a magnetic field within a microfluidic channel their velocity depends on the presence of analyte. Specifically, their velocity decreases drastically when the magnetic microparticles are covered by (nonmagnetic) analyte (LMPs) due to the increased drag force in the opposite direction to that of the magnetic force. Experiments were carried out as a proof of concept. A promising 52% decrease in the velocity of the LMPs in comparison to that of the MPs was measured when both of them were accelerated inside a microfluidic channel using an external permanent magnet. The presented biosensing methodology offers a compact and integrated solution for a new kind of on-chip analysis with potentially high sensitivity and shorter acquisition time than conventional laboratory based systems.

  5. Theoretical analysis of ferromagnetic microparticles in streaming liquid under the influence of external magnetic forces

    International Nuclear Information System (INIS)

    Brandl, Martin; Mayer, Michael; Hartmann, Jens; Posnicek, Thomas; Fabian, Christian; Falkenhagen, Dieter

    2010-01-01

    The microsphere based detoxification system (MDS) is designed for high specific toxin removal in extracorporeal blood purification using functionalized microparticles. A thin wall hollow fiber membrane filter separates the microparticle-plasma suspension from the bloodstream. For patient safety, it is necessary to have a safety system to detect membrane ruptures that could lead to the release of microparticles into the bloodstream. A non-invasive optical detection system including a magnetic trap is developed to monitor the extracorporeal venous bloodstream for the presence of released microparticles. For detection, fluorescence-labeled ferromagnetic beads are suspended together with adsorbent particles in the MDS circuit. In case of a membrane rupture, the labeled particles would be released into the venous bloodstream and partly captured by the magnetic trap of the detector. A physical model based on fluidic, gravitational and magnetic forces was developed to simulate the motion and sedimentation of ferromagnetic particles in a magnetic trap. In detailed simulation runs, the concentrations of accumulated particles under different applied magnetic fields within the magnetic trap are shown. The simulation results are qualitatively compared with laboratory experiments and show excellent accordance. Additionally, the sensitivity of the particle detection system is proofed in a MDS laboratory experiment by simulation of a membrane rupture.

  6. Metals separation using solvent extractants on magnetic microparticles

    International Nuclear Information System (INIS)

    Nunez, L.; Pourfarzaneh, M.

    1997-01-01

    The magnetically assisted chemical separation program was initially funded by DOE EM-50 to develop processes for the efficient separation of radionuclides and other hazardous metals. This process has simulated the partnership between industry and ANL for many applications related to hazardous metal problems in industry. In-tank or near-tank hazardous metals separation using magnetic particles promises simple, compact processing at very low costs and employs mature chemical separations technologies to remove and recover hazardous metals from aqueous solutions. The selective chemical extractants are attached to inexpensive magnetic carrier particles. Surfaces of small particles composed of rare earths or ferromagnetic materials are treated to retain chemical extractants (e.g., TBP, CMPO, quaternary amines, carboxylic acid). After selective partitioning of contaminants to the surface layer, magnets are used to collect the loaded particles from the tank. The particles can be regenerated by stripping the contaminants and the selective metals can be recovered and recycled from the strip solution. This process and its related equipment are simple enough to be used for recovery/recycling and waste minimization activities at many industrial sites. Both the development of the process for hazardous and radioactive waste and the transfer of the technology will be discussed

  7. Dynamic transformation of self-assembled structures using anisotropic magnetized hydrogel microparticles

    Science.gov (United States)

    Yoshida, Satoru; Takinoue, Masahiro; Iwase, Eiji; Onoe, Hiroaki

    2016-08-01

    This paper describes a system through which the self-assembly of anisotropic hydrogel microparticles is achieved, which also enables dynamic transformation of the assembled structures. Using a centrifuge-based microfluidic device, anisotropic hydrogel microparticles encapsulating superparamagnetic materials on one side are fabricated, which respond to a magnetic field. We successfully achieve dynamic assembly using these hydrogel microparticles and realize three different self-assembled structures (single and double pearl chain structures, and close-packed structures), which can be transformed to other structures dynamically via tuning of the precessional magnetic field. We believe that the developed system has potential application as an effective platform for a dynamic cell manipulation and cultivation system, in biomimetic autonomous microrobot organization, and that it can facilitate further understanding of the self-organization and complex systems observed in nature.

  8. Magnetically responsive microparticles for targeted drug and radionuclide delivery

    International Nuclear Information System (INIS)

    Kaminski, M. D.; Ghebremeskel, A. N.; Nunez, L.; Kasza, K. E.; Chang, F.; Chien, T.-H.; Fisher, P. F.; Eastman, J. A.; Rosengart, A. J.; McDonald, L.; Xie, Y.; Johns, L.; Pytel, P.; Hafeli, U. O.

    2004-01-01

    We are currently investigating the use of magnetic particles--polymeric-based spheres containing dispersed magnetic nanocrystalline phases--for the precise delivery of drugs via the human vasculature. According to this review, meticulously prepared magnetic drug targeting holds promise as a safe and effective method of delivering drugs to specific organ, tissue or cellular targets. We have critically examined the wide range of approaches in the design and implementation of magnetic-particle-based drug delivery systems to date, including magnetic particle preparation, drug encapsulation, biostability, biocompatibility, toxicity, magnetic field designs, and clinical trials. However, we strongly believe that there are several limitations with past developments that need to be addressed to enable significant strides in the field. First, particle size has to be carefully chosen. Micrometer-sized magnetic particles are better attracted over a distance than nanometer sized magnetic particles by a constant magnetic field gradient, and particle sizes up to 1 (micro)m show a much better accumulation with no apparent side effects in small animal models, since the smallest blood vessels have an inner diameter of 5-7 (micro)m. Nanometer-sized particles <70 nm will accumulate in organ fenestrations despite an effective surface stabilizer. To be suitable for future human applications, our experimental approach synthesizes the magnetic drug carrier according to specific predefined outcome metrics: monodisperse population in a size range of 100 nm to 1.0 (micro)m, non-toxic, with appropriate magnetic properties, and demonstrating successful in vitro and in vivo tests. Another important variable offering possible improvement is surface polarity, which is expected to prolong particle half-life in circulation and modify biodistribution and stability of drugs in the body. The molecules in the blood that are responsible for enhancing the uptake of particles by the reticuloendothelial

  9. Enzymatic removal of N-glycans by PNGase F coated magnetic microparticles

    Czech Academy of Sciences Publication Activity Database

    Bodnar, J.; Szekrényes, A.; Szigeti, M.; Járvás, G.; Křenková, Jana; Foret, František; Guttman, A.

    2016-01-01

    Roč. 37, č. 10 (2016), s. 1264-1269 ISSN 0173-0835 R&D Projects: GA ČR(CZ) GA14-06319S Institutional support: RVO:68081715 Keywords : PNGase F * magnetic microparticles * immobilization Subject RIV: CB - Analytical Chemistry , Separation Impact factor: 2.744, year: 2016

  10. Self-assembly of silica microparticles in magnetic multiphase flows: Experiment and simulation

    Science.gov (United States)

    Li, Xiang; Niu, Xiao-Dong; Li, You; Chen, Mu-Feng

    2018-04-01

    Dynamic self-assembly, especially self-assembly under magnetic field, is vital not only for its marvelous phenomenon but also for its mechanisms. Revealing the underlying mechanisms is crucial for a deeper understanding of self-assembly. In this paper, several magnetic induced self-assembly experiments by using the mixed magnetic multiphase fluids comprised of silica microspheres were carried out. The relations of the strength of external magnetic field, the inverse magnetorheological effect, and the structures of self-assembled particles were investigated. In addition, a momentum-exchanged immersed boundary-based lattice Boltzmann method (MEIB-LBM) for modeling multi-physical coupling multiphase flows was employed to numerically study the magnetic induced self-assembly process in detail. The present work showed that the external magnetic field can be used to control the form of self-assembly of nonmagnetic microparticles in a chain-like structure, and the self-assembly process can be classified into four stages with magnetic hysteresis, magnetization of nonmagnetic microparticles, self-assembly in chain-like structures, and the stable chain state. The combination of experimental and numerical results could offer a method to control the self-assembled nonmagnetic microparticles, which can provide the technical and theoretical support for the design and fabrication of micro/nanomaterials.

  11. Magnetic vinylphenyl boronic acid microparticles for Cr(VI) adsorption: Kinetic, isotherm and thermodynamic studies

    International Nuclear Information System (INIS)

    Kara, Ali; Demirbel, Emel; Tekin, Nalan; Osman, Bilgen; Beşirli, Necati

    2015-01-01

    Highlights: • Cr(VI) can oxidize biological molecules and be one of the most harmful substance. • Magnetic seperation techniques are used on different applications in many fields. • Magnetic systems can be used for rapid and selective removal as a magnetic processor. • We investigate properties of both new material and other magnetic adsorbents reported in the literatures on the adsorption of Cr(VI) ions. • No researchments were reported on adsorption of Cr(VI) with magnetic vinylphenyl boronic acid microparticles. - Abstract: Magnetic vinylphenyl boronic acid microparticles, poly(ethylene glycol dimethacrylate(EG)–vinylphenyl boronic acid(VPBA)) [m-poly(EG–VPBA)], produced by suspension polymerization and characterized, was found to be an efficient solid polymer for Cr(VI) adsorption. The m-poly(EG–VPBA) microparticles were prepared by copolymerizing of ethylene glycol dimethylacrylate (EG) with 4-vinyl phenyl boronic acid (VPBA). The m-poly(EG–VPBA) microparticles were characterized by N 2 adsorption/desorption isotherms, electron spin resonance (ESR), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), elemental analysis, scanning electron microscope (SEM) and swelling studies. The m-poly(EG–VPBA) microparticles were used at adsorbent/Cr(VI) ion ratios. The influence of pH, Cr(VI) initial concentration, temperature of the removal process was investigated. The maximum removal of Cr(VI) was observed at pH 2. Langmuir isotherm and Dubinin–Radushkvich isotherm were found to better fit the experiment data rather than Fruendlich isotherm. The kinetics of the adsorption process of Cr(VI) on the m-poly(EG–VPBA) microparticles were investigated using the pseudo first-order, pseudo-second-order, Ritch-second-order and intraparticle diffusion models, results showed that the pseudo-second order equation model provided the best correlation with the experimental results. The thermodynamic

  12. Parameters concerning the preparation and performance of a magnetic microparticle antibody

    International Nuclear Information System (INIS)

    Rongsen, Shen; Ruiyun, Xing; Fengqi, Zhou; Xiuzhen, Liu; Dingquan, Wang

    1997-01-01

    We have described 'Magnetic Microparticle Antibodies and Their Application to RIAs' in a recently published paper. In this article operative parameters for the preparation of a magnetic second antibody (MSA-II) including results of purification of donkey anti-rabbit (D X R) serum by an (NH 4 ) 2 SO 4 precipitation method, rates of recovery of products in preparation of magnetic nucleus (MN, Fe 3 O 4 microparticle), in distillation of acrolein (AL) and in preparation of polyacrolein magnetic particle (PAMP), change in pH value of suspension irradiated before and after 60 Co γ-irradiation and volume of wet sediment in separation of magnetic particles by a magnetic separator, etc., as well as correlation of levels of quality control (QC) sera obtained with liquid-phase double antibody assay (LDA) and MSA-II assay during four years were supplementarily summarized. These operative parameters would be helpful to mastering the procedures for preparation and/or use of the magnetic particles. The better correlation of levels of QC sera for both the assays showed the reliability of the magnetic antibody. (author)

  13. Magnetic-Responsive Microparticles that Switch Shape at 37 °C

    Directory of Open Access Journals (Sweden)

    Koichiro Uto

    2017-11-01

    Full Text Available Shape-memory polymers have seen tremendous research efforts driven by the need for better drug carries and biomedical devices. In contrast to these advancements, fabrication of shape-memory particles which actuate at body temperature remains scarce. We developed a shape-memory microparticle system with dynamically tunable shapes under physiological temperature. Temperature-responsive poly(ε-caprolactone (PCL microparticles were successfully prepared by an in situ oil-in-water (o/w emulsion polymerization technique using linear telechelic and tetra-branched PCL macromonomers. By optimizing the mixing ratios of branched PCL macromonomers, the crystal-amorphous transition temperature was adjusted to the biological relevant temperature. The particles with a disk-like temporal shape were achieved by compression. The shape recovery from the disk to spherical shape was also realized at 37 °C. We also incorporated magnetic nanoparticles within the PCL microparticles, which can be remote-controllable by a magnet, in such a way that they can be actuated and manipulated in a controlled way.

  14. Robust and Optimal Control of Magnetic Microparticles inside Fluidic Channels with Time-Varying Flow Rates

    Directory of Open Access Journals (Sweden)

    Islam S.M. Khalil

    2016-06-01

    Full Text Available Targeted therapy using magnetic microparticles and nanoparticles has the potential to mitigate the negative side-effects associated with conventional medical treatment. Major technological challenges still need to be addressed in order to translate these particles into in vivo applications. For example, magnetic particles need to be navigated controllably in vessels against flowing streams of body fluid. This paper describes the motion control of paramagnetic microparticles in the flowing streams of fluidic channels with time-varying flow rates (maximum flow is 35 ml.hr−1. This control is designed using a magnetic-based proportional-derivative (PD control system to compensate for the time-varying flow inside the channels (with width and depth of 2 mm and 1.5 mm, respectively. First, we achieve point-to-point motion control against and along flow rates of 4 ml.hr−1, 6 ml.hr−1, 17 ml.hr−1, and 35 ml.hr−1. The average speeds of single microparticle (with average diameter of 100 μm against flow rates of 6 ml.hr−1 and 30 ml.hr−1 are calculated to be 45 μm.s−1 and 15 μm.s−1, respectively. Second, we implement PD control with disturbance estimation and compensation. This control decreases the steady-state error by 50%, 70%, 73%, and 78% at flow rates of 4 ml.hr−1, 6 ml.hr−1, 17 ml.hr−1, and 35 ml.hr−1, respectively. Finally, we consider the problem of finding the optimal path (minimal kinetic energy between two points using calculus of variation, against the mentioned flow rates. Not only do we find that an optimal path between two collinear points with the direction of maximum flow (middle of the fluidic channel decreases the rise time of the microparticles, but we also decrease the input current that is supplied to the electromagnetic coils by minimizing the kinetic energy of the microparticles, compared to a PD control with disturbance compensation.

  15. [Magnetic Fe₃O₄Microparticles Conditioning-Pressure Electro-osmotic Dewatering (MPEOD) of Sewage Sludge].

    Science.gov (United States)

    Qian, Xu; Wang, Yi-li; Zhao, Li

    2016-05-15

    For magnetic Fe₃O₄ microparticles conditioning--pressure electro-osmotic dewatering (MPEOD) process of activated sludge (AS), the effects of operating parameters (optimal dosage of Fe₃O₄, electric field duration, mechanical pressure and voltage) on the dewatering efficiency and energy consumption were investigated, and the optimal conditions were determined. Moreover, the properties of supernatant and sludge along MPEOD process were studied as well as the interaction force between the sludge biosolids. Taking the energy consumption into consideration, the results showed that the optimal dewatering effect for AS could be achieved with a magnetic Fe₃O₄ microparticles dosage of 0.15 g · g⁻¹, an electric field duration of 2 h, a mechanical pressure of 400-600 kPa and a voltage of 30-50 V. When MPEOD was conducted at 400 kPa and 50 V for 2 h, the sludge reduction rate reached 98.30%, the percentage of water removal was 99.34% and the moisture content of AS decreased from 99.18% to 44.46%. The corresponding consumption of energy was 0.013 3 kW · h · kg⁻¹. The coagulation mechanism played a slight role in the AS conditioning with magnetic Fe₃O₄ micro-particles. In fact, magnetic Fe₃O₄micro-particles could greatly decrease the acid-base interaction (WA) between AS biosolids, cause floc growth and enlarge pores in AS aggregates, which will be beneficial to AS dewatering. Compared to DLVO theory, the extended DLVO theory could accurately describe the aggregation and dispersion behavior of sludge particles.

  16. Magnetic Generation due to Mass Difference between Charge Carriers

    OpenAIRE

    Chen, Shi; Dan, JiaKun; Chen, ZiYu; Li, JianFeng

    2013-01-01

    The possibility of spontaneous magnetization due to the "asymmetry in mass" of charge carriers in a system is investigated. Analysis shows that when the masses of positive and negative charge carriers are identical, no magnetization is predicted. However, if the masses of two species are different, spontaneous magnetic field would appear, either due to the equipartition of magnetic energy or due to fluctuations together with a feedback mechanism. The conditions for magnetization to occur are ...

  17. Evaluation of extractant-coated magnetic microparticles for the recovery of hazardous metals from waste solution

    International Nuclear Information System (INIS)

    Kaminski, M. D.

    1998-01-01

    A magnetically assisted chemical separation (MACS) process was developed earlier at Argonne National Laboratory (ANL). This compact process was designed for the separation of transuranics (TRU) and radionuclides from the liquid waste streams that exist at many DOE sites, with an overall reduction in waste volume requiring disposal. The MACS process combines the selectivity afforded by solvent extractant/ion exchange materials with magnetic separation to provide an efficient chemical separation. Recently, the MACS process has been evaluated with acidic organophosphorus extractants for hazardous metal recovery from waste solutions. Moreover, process scale-up design issues have been addressed with respect to particle filtration and recovery. Two acidic organophosphorus compounds have been investigated for hazardous metal recovery, bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanexreg-sign 272) and bis(2,4,4-trimethylpentyl) dithiophosphinic acid (Cyanexreg-sign 301). Coated onto magnetic microparticles, these extractants demonstrated superior recovery of hazardous metals from solution, relative to what was expected on the basis of results from solvent extraction experiments. The results illustrate the diverse applications of MACS technology for dilute waste streams. Preliminary process scale-up experiments with a high-gradient magnetic separator at Oak Ridge National Laboratory have revealed that very low microparticle loss rates are possible

  18. Stabilisation effects of superparamagnetic nanoparticles on clustering in nanocomposite microparticles and on magnetic behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Mandel, K., E-mail: karl-sebastian.mandel@isc.fraunhofer.de [Fraunhofer Institute for Silicate Research, ISC, Neunerplatz 2, 97082 Würzburg (Germany); University Würzburg, Chair of Chemical Technology of Materials Synthesis, Röntgenring 11, 97070 Würzburg (Germany); Hutter, F., E-mail: frank.hutter@isc.fraunhofer.de [Fraunhofer Institute for Silicate Research, ISC, Neunerplatz 2, 97082 Würzburg (Germany); Gellermann, C., E-mail: carsten.gellermann@isc.fraunhofer.de [Fraunhofer Institute for Silicate Research, ISC, Neunerplatz 2, 97082 Würzburg (Germany); Sextl, G., E-mail: gerhard.sextl@isc.fraunhofer.de [Fraunhofer Institute for Silicate Research, ISC, Neunerplatz 2, 97082 Würzburg (Germany); University Würzburg, Chair of Chemical Technology of Materials Synthesis, Röntgenring 11, 97070 Würzburg (Germany)

    2013-04-15

    Superparamagnetic nanoparticles of magnetite were coprecipitated from iron salts, dispersed with nitric acid and stabilised either by lactic acid (LA) or by a polycarboxylate-ether polymer (MELPERS4343, MP). The differently stabilised nanoparticles were incorporated into a silica matrix to form nanocomposite microparticles. The silica matrix was prepared either from tetraethylorthosilicate (TEOS) or from an aqueous sodium silicate (water glass) solution. Stabilisation of nanoparticles had a crucial influence on microparticle texture and nanoparticle distribution in the silica matrix. Magnetic measurements in combination with transmission electron microscopy (TEM) investigations suggest a uniform magnetic interaction of nanoparticles in case of LA stabilisation and magnetically interacting nanoparticle clusters of different sizes in case of MP stabilisation. Splitting of blocking temperature (T{sub B}) and irreversible temperature (T{sub ir}) in zero field cooled (ZFC) and field cooled (FC) measurements is discussed in terms of nanoparticle clustering. -- Highlights: ► Superparamagnetic nanoparticles were synthesised, dispersed and stabilised. ► Stabilisation is either via a polycarboxylate ether polymer or lactic acid. ► Stabilised nanoparticles were incorporated into silica to form composite particles. ► Depending on the stabilisation, nanoparticle clustering in the composites differed. ► Clustering influences zero field cooled/field cooled magnetic measurements.

  19. Microscale magnetic microparticle-based immunopurification of cytokinins from Arabidopsis root apex

    Czech Academy of Sciences Publication Activity Database

    Plačková, Lenka; Oklešťková, Jana; Pospíšková, K.; Poláková, K.; Buček, J.; Stýskala, J.; Zatloukal, M.; Šafařík, Ivo; Zbořil, R.; Strnad, Miroslav; Doležal, Karel; Novák, Ondřej

    2017-01-01

    Roč. 89, č. 5 (2017), s. 1065-1075 ISSN 0960-7412 R&D Projects: GA MŠk(CZ) LO1204; GA MŠk LK21306; GA ČR GA14-34792S Institutional support: RVO:61389030 ; RVO:60077344 Keywords : solid-phase extraction * tandem mass-spectrometry * endogenous cytokinins * plant-samples * cis-zeatin * quantitative-analysis * aromatic cytokinins * abscisic-acid * oryza-sativa * purification * cytokinins * magnetic microparticles * immunoaffinity separation * metabolite profiling * Arabidopsis thaliana * technical advance Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Plant sciences, botany Impact factor: 5.901, year: 2016

  20. Simultaneous capture and sequential detection of two malarial biomarkers on magnetic microparticles.

    Science.gov (United States)

    Markwalter, Christine F; Ricks, Keersten M; Bitting, Anna L; Mudenda, Lwiindi; Wright, David W

    2016-12-01

    We have developed a rapid magnetic microparticle-based detection strategy for malarial biomarkers Plasmodium lactate dehydrogenase (pLDH) and Plasmodium falciparum histidine-rich protein II (PfHRPII). In this assay, magnetic particles functionalized with antibodies specific for pLDH and PfHRPII as well as detection antibodies with distinct enzymes for each biomarker are added to parasitized lysed blood samples. Sandwich complexes for pLDH and PfHRPII form on the surface of the magnetic beads, which are washed and sequentially re-suspended in detection enzyme substrate for each antigen. The developed simultaneous capture and sequential detection (SCSD) assay detects both biomarkers in samples as low as 2.0parasites/µl, an order of magnitude below commercially available ELISA kits, has a total incubation time of 35min, and was found to be reproducible between users over time. This assay provides a simple and efficient alternative to traditional 96-well plate ELISAs, which take 5-8h to complete and are limited to one analyte. Further, the modularity of the magnetic bead-based SCSD ELISA format could serve as a platform for application to other diseases for which multi-biomarker detection is advantageous. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  1. Microfluidic biosensing device for controlled trapping and detection of magnetic microparticles

    KAUST Repository

    Giouroudi, Ioanna

    2013-05-01

    A magnetic microfluidic device is proposed to transport and trap magnetic microparticles (MPs) to a sensing area. Once the MPs are concentrated in the vicinity of the sensing area, a spin valve type giant magnetoresistance (GMR) sensor is used to detect their presence. The device is used for the detection of biological targets once they are labeled with functionalized MPs. Manipulation of the MPs is achieved by employing a microstructure which consists of planar ringshaped conducting microloops. These microloops are designed to produce high magnetic field gradients which are directly proportional to the force applied to manipulate the MPs. Upon sequential application of current, starting from the outermost loop, MPs are directed to move from the outermost to the innermost loop. The speed with which the MPs move towards the sensing area is controlled by the speed with which current is switched between the loops. On top of the microstructure, a microfluidic channel is fabricated using a standard photolithography technique and a dry film resist layer (Ordyl SY355). Experimental results showed that MPs of different diameters were successfully trapped at the sensing area and detected by the GMR sensor located directly under the innermost square loop. © 2013 IEEE.

  2. Fabrication of PLA/CaCO3 hybrid micro-particles as carriers for water-soluble bioactive molecules.

    Science.gov (United States)

    Kudryavtseva, Valeriya L; Zhao, Li; Tverdokhlebov, Sergei I; Sukhorukov, Gleb B

    2017-09-01

    We propose the use of polylactic acid/calcium carbonate (PLA/CaCO 3 ) hybrid micro-particles for achieving improved encapsulation of water-soluble substances. Biodegradable porous CaCO 3 microparticles can be loaded with wide range of bioactive substance. Thus, the formation of hydrophobic polymeric shell on surface of these loaded microparticles results on encapsulation and, hence, sealing internal cargo and preventing their release in aqueous media. In this study, to encapsulate proteins, we explore the solid-in-oil-in-water emulsion method for fabricating core/shell PLA/CaCO 3 systems. We used CaCO 3 particles as a protective core for encapsulated bovine serum albumin, which served as a model protein system. We prepared a PLA coating using dichloromethane as an organic solvent and polyvinyl alcohol as a surfactant for emulsification; in addition, we varied experimental parameters such as surfactant concentration and polymer-to-CaCO 3 ratio to determine their effect on particle-size distribution, encapsulation efficiency and capsule permeability. The results show that the particle size decreased and the size distribution narrowed as the surfactant concentration increased in the external aqueous phase. In addition, when the CaCO 3 /PLA mass ratio dropped below 0.8, the hybrid micro-particles were more likely to resist treatment by ethylenediaminetetraacetic acid and thus retained their bioactive cargos within the polymer-coated micro-particles. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Magnetic suspension and pointing system. [on a carrier vehicle

    Science.gov (United States)

    Anderson, W. W.; Groom, N. J. (Inventor)

    1979-01-01

    Apparatus for providing accurate pointing of instruments on a carrier vehicle and for providing isolation of the instruments from the vehicle's motion disturbances is presented. The apparatus includes two assemblies, with connecting interfaces, each assembly having a separate function. The first assembly is attached to the carrier vehicle and consists of an azimuth gimbal and an elevation gimbal which provide coarse pointing of the instruments by allowing two rotations of the instruments relative to the carrier vehicle. The second or vernier pointing assembly is made up of magnetic suspension and fine pointing actuators, roll motor segments, and an instrument mounting plate around which a continuous annular rim is attached which provides appropriate magnetic circuits for the actuators and the roll motor segments. The vernier pointing assembly provides six degree-of-freedom isolation from carrier motion disturbances.

  4. Mechanism of carrier-induced ferromagnetism in diluted magnetic semiconductors

    International Nuclear Information System (INIS)

    Takahashi, M.; Furukawa, N.; Kubo, K.

    2004-01-01

    Using the spin-polarized band obtained by applying the dynamical coherent potential approximation to a simple model, we have calculated the magnetization of Ga x Mn 1-x As as a function of the temperature for various values of carrier density. The result is consistent with the experimental observation, supporting the view previously proposed by us that the ferromagnetism is induced by the carriers in the bandtail through double-exchange-like mechanism

  5. Development of magnetic microparticle antibodies and their application to RIA's for the evaluation of the thyroid function

    International Nuclear Information System (INIS)

    Shen Rongsen; Wang Renzhi; Xing Ruiyun; Li Yingqi; Zhou Fengqi; Jiang Shaohua; Lin Zhihao; Xu Banglei

    1996-01-01

    Three type of magnetic microparticle antibodies were developed: (1) magnetic second antibody I (MSA-I) where the antibody molecules were directly immobilized by physical adsorption on Fe 3 O 4 microparticles (magnetic nucleus, MN) 10 nm ± 34% in diameter; (2) magnetic second antibody II (MSA-II) where the antibody molecules were immobilized by chemical coupling on the MN coated with polyacrolein; and (3) magnetic first antibody (MFA-T 3 ) where the anti-T 3 antibody molecules were specifically immobilized by immunoadsorption to the second antibody molecules of the MSA-II. The optimal conditions for their preparation were elaborated. Some physical, chemical and immunological characteristics of these magnetic microparticles were described. The application of the MSA-I, MSAII and MFA-T 3 to RIAs for evaluation of thyroid function, such as triiodothyronine (T 3 ), reverse T 3 (rT 3 ), free T 3 (fT 3 ), thyroxine (T 4 ), free T 4 (fT 4 ), thyroid-stimulating hormone (TSH), thyroglobulin (TG) and TG-antibody (TG-Ab) etc., was reported. The preparation of MFA-T 3 was based on a new model of immobilized antibodies. It was shown that this immobilized model was successful but some technical problems related to the performance of antibody magnetic support remained to be solved. The MSA-I had an advantage of extremely simple preparation and could be prepared and used in anyone's own laboratory. The MSA-II exhibited more perfect performance and was therefore highly recommended. It is a universal immunoseparation reagent and could be successfully applied to different RIA items. (author). 14 refs, 10 figs, 6 tabs

  6. Magnetic Vinylphenyl Boronic Acid Microparticles for Surface Catalytic Performance in Esterification of Propionic Acid with Methanol

    Directory of Open Access Journals (Sweden)

    Ali Kara

    2016-12-01

    Full Text Available Magnetic vinylphenyl boronic acid microparticles, poly(ethylene glycol dimethacrylate-vinylphenyl boronic acid [m-poly(EGDMA-VPBA], produced by suspension polymerization, was found to be efficient solid acid catalyst for the esterification of methanol and propionic acid. Characterization techniques such as FT-IR, Elemental analyses, ICP-AES, ESR, SEM and N2 sorption showed that both of Fe3O4 and H2SO4 are bonded to the polymer successfully. Esterification was studied for different molar percentages of H2SO4 at temperature range of 50-70 oC. The apparent activation energy was found to be 27.7 kj.mol-1 for 10% H2SO4 doped m-poly(EGDMA-VPBA. Combining of strong acid H2SO4 with m-poly(EGDMA-VPBA, leads to materials with different functional properties. In addition, H2SO4 species could be introduced into the structure as acid centers, therefore this micro-dimensional catalyst has potential candidate for applications in the catalytic esterifications such as propionic acid with methanol.

  7. Carrier tunneling in high magnetic fields

    NARCIS (Netherlands)

    Christianen, P.C.M.; Bruggink, I.E.M.; Maan, J.C.; Vleuten, van der W.C.

    1995-01-01

    Proceedings of the XXIV International School of Semiconducting Coinpounds, Jaszowiec 1995. A magnetic field induced coupling is observed between the Landau levels with different quantum number of two GaAs quantum wells separated by a thin (Ga,Al)As tunnel barrier using

  8. Magnetic Resonance Imaging of Atherosclerosis Using CD81-Targeted Microparticles of Iron Oxide in Mice

    Directory of Open Access Journals (Sweden)

    Fei Yan

    2015-01-01

    Full Text Available The goal of this study is to investigate the feasibility of using CD81- (Cluster of Differentiation 81 protein- targeted microparticles of iron oxide (CD81-MPIO for magnetic resonance imaging (MRI of the murine atherosclerosis. CD81-MPIO and IgG- (Immunoglobulin G- MPIO were prepared by covalently conjugating, respectively, with anti-CD81 monoclonal and IgG antibodies to the surface of the tosyl activated MPIO. The relevant binding capability of the MPIO was examined by incubating them with murine bEnd.3 cells stimulated with phenazine methosulfate (PMS and its effect in shortening T2 relaxation time was also examined. MRI in apolipoprotein E-deficient mice was studied in vivo. Our results show that CD81-MPIO, but not IgG-MPIO, can bind to the PMS-stimulated bEnd.3 cells. The T2 relaxation time was significantly shortened for stimulated bEnd.3 cells when compared with IgG-MPIO. In vivo MRI in apolipoprotein E-deficient mice showed highly conspicuous areas of low signal after CD81-MPIO injection. Quantitative analysis of the area of CD81-MPIO contrast effects showed 8.96- and 6.98-fold increase in comparison with IgG-MPIO or plain MPIO, respectively (P<0.01. Histological assay confirmed the expression of CD81 and CD81-MPIO binding onto atherosclerotic lesions. In conclusion, CD81-MPIO allows molecular assessment of murine atherosclerotic lesions by magnetic resonance imaging.

  9. Drug- not carrier-dependent haematological and biochemical changes in a repeated dose study of cyclosporine encapsulated polyester nano- and micro-particles: Size does not matter

    International Nuclear Information System (INIS)

    Venkatpurwar, V.P.; Rhodes, S.; Oien, K.A.; Elliott, M.A.; Tekwe, C.D.; Jørgensen, H.G.; Kumar, M.N.V. Ravi

    2015-01-01

    Highlights: • The particulate delivery allows an increase in dose range without accrual of toxicities. • The altered haematological and biochemical changes are drug, but not particle dependent. • PLGA nano/microparticles are safe on subacute peroral dosing over 28 days. • Nano-toxicology, drug needs to be considered. - Abstract: Biodegradable nanoparticles are being considered more often as drug carriers to address pharmacokinetic/pharmacodynamic issues, yet nano-product safety has not been systematically proven. In this study, haematological, biochemical and histological parameters were examined on 28 day daily dosing of rats with nano- or micro-particle encapsulated cyclosporine (CsA) to confirm if any changes observed were drug or carrier dependent. CsA encapsulated poly(lactide-co-glycolide) [PLGA] nano- (nCsA) and micro-particles (mCsA) were prepared by emulsion techniques. CsA (15, 30, 45 mg/kg) were administered by oral gavage to Sprague Dawley (SD) rats over 28 days. Haematological and biochemical metrics were followed with tissue histology performed on sacrifice. Whether presented as nCsA or mCsA, 45 mg/kg dose caused significant loss of body weight and lowered food consumption compared to untreated control. Across the doses, both nCsA and mCsA produce significant decreases in lymphocyte numbers compared to controls, commensurate with the proprietary product, Neoral ® 15. Dosing with nCsA showed higher serum drug levels than mCsA presumably owing to the smaller particle size facilitating absorption. The treatment had no noticeable effects on inflammatory/oxidative stress markers or antioxidant enzyme levels, except an increase in ceruloplasmin (CP) levels for high dose nCsA/mCsA group. Further, only subtle, sub-lethal changes were observed in histology of nCsA/mCsA treated rat organs. Blank (drug-free) particles did not induce changes in the parameters studied. Therefore, it is extremely important that the encapsulated drug in the nano-products is

  10. Magnetic and in vitro heating properties of implants formed in situ from injectable formulations and containing superparamagnetic iron oxide nanoparticles (SPIONs) embedded in silica microparticles for magnetically induced local hyperthermia

    International Nuclear Information System (INIS)

    Le Renard, Pol-Edern; Lortz, Rolf; Senatore, Carmine; Rapin, Jean-Philippe; Buchegger, Franz; Petri-Fink, Alke; Hofmann, Heinrich; Doelker, Eric; Jordan, Olivier

    2011-01-01

    The biological and therapeutic responses to hyperthermia, when it is envisaged as an anti-tumor treatment modality, are complex and variable. Heat delivery plays a critical role and is counteracted by more or less efficient body cooling, which is largely mediated by blood flow. In the case of magnetically mediated modality, the delivery of the magnetic particles, most often superparamagnetic iron oxide nanoparticles (SPIONs), is also critically involved. We focus here on the magnetic characterization of two injectable formulations able to gel in situ and entrap silica microparticles embedding SPIONs. These formulations have previously shown suitable syringeability and intratumoral distribution in vivo. The first formulation is based on alginate, and the second on a poly(ethylene-co-vinyl alcohol) (EVAL). Here we investigated the magnetic properties and heating capacities in an alternating magnetic field (141 kHz, 12 mT) for implants with increasing concentrations of magnetic microparticles. We found that the magnetic properties of the magnetic microparticles were preserved using the formulation and in the wet implant at 37 o C, as in vivo. Using two orthogonal methods, a common SLP (20 W g -1 ) was found after weighting by magnetic microparticle fraction, suggesting that both formulations are able to properly carry the magnetic microparticles in situ while preserving their magnetic properties and heating capacities. - Research highlights: → Magnetic formulations that form implants on injection into tissues are proposed for hyperthermia. → Superparamagnetic properties of the SPION-silica composite microparticles are preserved in the wet implants. → Heat-dissipating properties (SLP of 20 W/g of implant) support in vivo use.

  11. Magnetic tagging of cell-derived microparticles: new prospects for imaging and manipulation of these mediators of biological information.

    Science.gov (United States)

    Vats, Nidhi; Wilhelm, Claire; Rautou, Pierre-Emmanuel; Poirier-Quinot, Marie; Péchoux, Christine; Devue, Cécile; Boulanger, Chantal M; Gazeau, Florence

    2010-07-01

    Submicron membrane fragments termed microparticles (MPs), which are released by apoptotic or activated cells, are newly considered as vectors of biological information and actors of pathology development. We propose the tagging of MPs with magnetic nanoparticles as a new approach allowing imaging, manipulation and targeting of cell-derived MPs. MPs generated in vitro from human endothelial cells or isolated from atherosclerotic plaques were labeled using citrate-coated 8 nm iron-oxide nanoparticles. MPs were tagged with magnetic nanoparticles on their surface and detected as Annexin-V positive by flow cytometry. Labeled MPs could be mobilized, isolated and manipulated at a distance in a magnetic field gradient. Magnetic mobility of labeled MPs was quantified by micromagnetophoresis. Interactions of labeled MPs with endothelial cells could be triggered and modulated by magnetic guidance. Nanoparticles served as tracers at different scales: at the subcellular level by electron microscopy, at the cellular level by histology and at the macroscopic level by MRI. Magnetic labeling of biogenic MPs opens new prospects for noninvasive monitoring and distal manipulations of these biological effectors.

  12. Synthesis and Characterization of Magnetic Carriers Based on Immobilized Enzyme

    Science.gov (United States)

    Li, F. H.; Tang, N.; Wang, Y. Q.; Zhang, L.; Du, W.; Xiang, J.; Cheng, P. G.

    2018-05-01

    Several new types of carriers and technologies have been implemented to improve traditional enzyme immobilization in industrial biotechnology. The magnetic immobilized enzyme is a kind of new method of enzyme immobilization developed in recent years. An external magnetic field can be used to control the motion mode and direction of immobilized enzyme, and to improve the catalytic efficiency of immobilized enzyme. In this paper, Fe3O4-CaCO3-PDA complex and CaCO3/Fe3O4 composite modified by PEI were prepared. The results show that the morphology of Fe3O4-CaCO3-PDA complex formation is irregular, while the morphology of CaCO3/Fe3O4 composite modified by PEI is regular and has a porous structure.

  13. Magnetic microparticles post-synthetically coated by hyaluronic acid as an enhanced carrier for microfluidic bioanalysis

    Czech Academy of Sciences Publication Activity Database

    Holubová, L.; Knotek, P.; Palarčik, J.; Čadková, M.; Bělina, P.; Vlček, Milan; Korecká, L.; Bílková, Z.

    2014-01-01

    Roč. 44, 1 November (2014), s. 345-351 ISSN 0928-4931 R&D Projects: GA ČR GAP206/12/0381 Institutional support: RVO:61389013 Keywords : coating * hyaluronic acid * hyaluronan Subject RIV: CA - Inorganic Chemistry Impact factor: 3.088, year: 2014

  14. The antibody-based magnetic microparticle immunoassay using p-FET sensing platform for Alzheimer's disease pathogenic factor

    Science.gov (United States)

    Kim, Chang-Beom; Kim, Kwan-Soo; Song, Ki-Bong

    2013-05-01

    The importance of early Alzheimer's disease (AD) detection has been recognized to diagnose people at high risk of AD. The existence of intra/extracellular beta-amyloid (Aβ) of brain neurons has been regarded as the most archetypal hallmark of AD. The existing computed-image-based neuroimaging tools have limitations on accurate quantification of nanoscale Aβ peptides due to optical diffraction during imaging processes. Therefore, we propose a new method that is capable of evaluating a small amount of Aβ peptides by using photo-sensitive field-effect transistor (p-FET) integrated with magnetic force-based microbead collecting platform and selenium(Se) layer (thickness ~700 nm) as an optical filter. This method demonstrates a facile approach for the analysis of Aβ quantification using magnetic force and magnetic silica microparticles (diameter 0.2~0.3 μm). The microbead collecting platform mainly consists of the p-FET sensing array and the magnet (diameter ~1 mm) which are placed beneath each sensing region of the p-FET, which enables the assembly of the Aβ antibody conjugated microbeads, captures the Aβ peptides from samples, measures the photocurrents generated by the Q-dot tagged with Aβ peptides, and consequently results in the effective Aβ quantification.

  15. Spin and energy transfer between magnetic ions and free carriers in diluted-magnetic semiconductor heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Yakovlev, D.R. [Experimental Physics 2, University of Dortmund, 44227 Dortmund (Germany); Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Kneip, M.; Bayer, M. [Experimental Physics 2, University of Dortmund, 44227 Dortmund (Germany); Maksimov, A.A.; Tartakovskii, I.I. [Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka (Russian Federation); Keller, D.; Ossau, W.; Molenkamp, L.W. [Physikalisches Institut der Universitaet Wuerzburg, 97074 Wuerzburg (Germany); Scherbakov, A.V.; Akimov, A.V. [Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Waag, A. [Abteilung Halbleiterphysik, Universitaet Ulm, 89081 Ulm (Germany)

    2004-03-01

    In this paper we give a brief overview of our studies on dynamical processes in diluted-magnetic-semiconductor heterostructures based on (Zn,Mn)Se and (Cd,Mn)Te. Presence of free carriers is an important factor which determines the energy- and spin transfer in a coupled systems of magnetic ions, lattice (the phonon system) and carriers. We report also new data on dynamical response of magnetic ions interacting with photogenerated electron-hole plasma. (Zn,Mn)Se/(Zn,Be)Se structures with relatively high Mn content of 11% provide spin-lattice relaxation time of about 20 ns, which is considerably shorter then the characteristic times of nonequilibrium phonons ranging to 1 {mu}s. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. High-yield synthesis of vaterite microparticles in gypsum suspension system via ultrasonic probe vibration/magnetic stirring

    Science.gov (United States)

    Wang, Bo; Pan, Zihe; Cheng, Huaigang; Chen, Zuliang; Cheng, Fangqin

    2018-06-01

    Vaterite-type calcium carbonate particles have some unique properties such as high hydrophilicity, large surface areas, and hierarchical structures consisting of primary vaterite particles in comparison with calcite or aragonite-type polymorphs. In this paper, gypsum (CaSO4·2H2O) suspension is used to synthesize micro-sized vaterite CaCO3 through magnetic stirring (MS) and ultrasonic probe vibration (UPV) methods. The effects of ammonia concentration, CO2 flow rate, solid-liquid ratio on the gypsum carbonation process, mineral phase composition, morphology and particle size distribution of CaCO3 are investigated. The results show that the carbonation process is significantly influenced by ammonia concentration, CO2 flow rate and ultrasound. Comparing with magnetic stirring, ultrasonic probe vibration take less time to reach the complete carbonate reaction. Gypsum is transformed to vaterite with the conversion rate about ∼95% when the mole ratio of NH4+/Ca2+ is 2.4 otherwise the carbonation reaction was uncompleted with gypsum residues left. Comparing with MS method, the UPV method resulted in smaller size and narrower size distribution of as-prepared microparticles and approximately 80% reduction of the particle size was achieved. It is established that increasing the solid-liquid ratio resulted in larger particle size in MS system and smaller particle size in UPV system. Increasing CO2 flow rate caused the particle size decreased in MS system and increased in UPV system.

  17. Magnetic microparticle-based SELEX process for the identification of highly specific aptamers of heart marker--brain natriuretic peptide

    International Nuclear Information System (INIS)

    Wang, Ying; Cao, Jinxuan; Wu, Jingjing; Xue, Feng; Teng, Jun; Chen, Wei; Chen, Yinji; Lu, Chunxia

    2015-01-01

    The brain natriuretic peptide (BNP) is known to be an effective indicator of heart failure. It has been widely adopted as a parameter for the evaluation of heart function of cardiovascular and cerebrovascular diseases (CVDs). Current immune-recognition based methods for the detection of BNP are limited, to a certain extent, by the poor stability of the antibody and by high costs. The availability of an aptamer specific for BNP would greatly assist in the rapid and early diagnosis of CVDs. In order to screen for such an aptamer by the SELEX method, we have used magnetic microparticles (m-MPs) as the separation substrate for immobilization of target BNP. The use of m-MPs for rapid separation of combined aptamers enables bound oligonucleotides to be separated directly, quickly, and with high efficiency. After 14 rounds of selection, a panel of six aptamers against BNP was identified. Their dissociation constants range from 12.5 to 139 nM. The classical technique for conjugation of a target to m-MPs is known to be applicable to various fields, and we conclude that this m-MP-based SELEX process provides a general strategy for screening of specific aptamers against various analytes. (author)

  18. Preparation and highlighted applications of magnetic microparticles and nanoparticles: a review on recent advances

    International Nuclear Information System (INIS)

    Xiao, Deli; Lu, Ting; Zeng, Rong; Bi, Yanping

    2016-01-01

    This review (with 144 refs.) focuses on the recent advances in the preparation and application of magnetic micro/nanoparticles. Specifically, it covers (a) methods for preparation (such as by coprecipitation, pyrolysis, hydrothermal, solvothermal, sol-gel, micro-emulsion, sonochemical, medium dispersing or emulsion polymerization methods), and (b) applications such as magnetic resonance imaging, magnetic separation of biomolecules (nucleic acids; proteins; cells), separation of metal ions and organic analytes, immobilization of enzymes, biological detection, magnetic catalysis and water treatment. Finally, the existing challenges and possible trends in the field are addressed. (author)

  19. Method of driving liquid flow at or near the free surface using magnetic microparticles

    Science.gov (United States)

    Snezhko, Oleksiy [Woodridge, IL; Aronson, Igor [Darien, IL; Kwok, Wai-Kwong [Evanston, IL; Belkin, Maxim V [Woodridge, IL

    2011-10-11

    The present invention provides a method of driving liquid flow at or near a free surface using self-assembled structures composed of magnetic particles subjected to an external AC magnetic field. A plurality of magnetic particles are supported at or near a free surface of liquid by surface tension or buoyancy force. An AC magnetic field traverses the free surface and dipole-dipole interaction between particles produces in self-assembled snake structures which oscillate at the frequency of the traverse AC magnetic field. The snake structures independently move across the free surface and may merge with other snake structures or break up and coalesce into additional snake structures experiencing independent movement across the liquid surface. During this process, the snake structures produce asymmetric flow vortices across substantially the entirety of the free surface, effectuating liquid flow across the free surface.

  20. Magnetic scanning gate microscopy of a domain wall nanosensor using microparticle probe

    Energy Technology Data Exchange (ETDEWEB)

    Corte-León, H., E-mail: hector.corte@npl.co.uk [National Physical Laboratory, Teddington TW11 0LW (United Kingdom); Royal Holloway University of London, Egham TW20 0EX (United Kingdom); Gribkov, B. [National Physical Laboratory, Teddington TW11 0LW (United Kingdom); Krzysteczko, P. [Physikalisch-Technische Bundesanstalt, Braunschweig D-38116 (Germany); Marchi, F.; Motte, J.-F. [University of Grenoble Alpes, Inst. NEEL, Grenoble F-38042 (France); CNRS, Inst. NEEL, Grenoble F-38042 (France); Schumacher, H.W. [Physikalisch-Technische Bundesanstalt, Braunschweig D-38116 (Germany); Antonov, V. [Royal Holloway University of London, Egham TW20 0EX (United Kingdom); Kazakova, O. [National Physical Laboratory, Teddington TW11 0LW (United Kingdom)

    2016-02-15

    We apply the magnetic scanning gate microscopy (SGM) technique to study the interaction between a magnetic bead (MB) and a domain wall (DW) trapped in an L-shaped magnetic nanostructure. Magnetic SGM is performed using a custom-made probe, comprising a hard magnetic NdFeB bead of diameter 1.6 µm attached to a standard silicon tip. The MB–DW interaction is detected by measuring changes in the electrical resistance of the device as a function of the tip position. By scanning at different heights, we create a 3D map of the MB–DW interaction and extract the sensing volume for different widths of the nanostructure's arms. It is shown that for 50 nm wide devices the sensing volume is a cone of 880 nm in diameter by 1.4 µm in height, and reduces down to 800 nm in height for 100 nm devices with almost no change in its diameter. - Highlights: • AFM tips with a magnetic bead attached used to test interaction with domain wall. • Domain wall inside a nanostructure affect the electrical resistance. • Recording electrical resistance while scanning with modified AFM probe. • Change of resistance as a function of the position of the magnetic bead. • This allows comparing different devices in a reproducible and controllable way.

  1. PEGylation of magnetic poly(glycidyl methacrylate) microparticles for microfluidic bioassays

    Czech Academy of Sciences Publication Activity Database

    Kučerová, J.; Svobodová, Z.; Knotek, P.; Palarčik, J.; Vlček, Milan; Kincl, Miloslav; Horák, Daniel; Autebert, J.; Viovy, J.-L.; Bílková, Z.

    2014-01-01

    Roč. 40, 1 July (2014), s. 308-315 ISSN 0928-4931 R&D Projects: GA MŠk 7E12053; GA MŠk 7E09109 EU Projects: European Commission(XE) 246513 - NADINE; European Commission(XE) 228980 - CAMINEMS Institutional support: RVO:61389013 Keywords : PEGylation * magnetic microscopy * microfluidics Subject RIV: CE - Biochemistry

  2. Carrier density control of magnetism and Berry phases in doped EuTiO3

    Science.gov (United States)

    Ahadi, Kaveh; Gui, Zhigang; Porter, Zach; Lynn, Jeffrey W.; Xu, Zhijun; Wilson, Stephen D.; Janotti, Anderson; Stemmer, Susanne

    2018-05-01

    In materials with broken time-reversal symmetry, the Berry curvature acts as a reciprocal space magnetic field on the conduction electrons and is a significant contribution to the magnetotransport properties, including the intrinsic anomalous Hall effect. Here, we report neutron diffraction, transport, and magnetization measurements of thin films of doped EuTiO3, an itinerant magnetic material, as a function of carrier density and magnetic field. These films are itinerant antiferromagnets at all doping concentrations. At low carrier densities, the magnetoresistance indicates a metamagnetic transition, which is absent at high carrier densities (>6 × 1020 cm-3). Strikingly, the crossover coincides with a sign change in the spontaneous Hall effects, indicating a sign change in the Berry curvature. We discuss the results in the context of the band structure topology and its coupling to the magnetic texture.

  3. Protein encapsulated magnetic carriers for micro/nanoscale drug delivery systems.

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Y.; Kaminski, M. D.; Mertz, C. J.; Finck, M. R.; Guy, S. G.; Chen, H.; Rosengart, A. J.; Chemical Engineering; Univ. of Chicago, Pritzker School of Medicine

    2005-01-01

    Novel methods for drug delivery may be based on nanotechnology using non-invasive magnetic guidance of drug loaded magnetic carriers to the targeted site and thereafter released by external ultrasound energy. The key building block of this system is to successfully synthesize biodegradable, magnetic drug carriers. Magnetic carriers using poly(D,L-lactide-co-glycolide) (PLGA) or poly(lactic acid)-poly(ethylene glycol) (PLA-PEG) as matrix materials were loaded with bovine serum albumin (BSA) by a double-emulsion technique. BSA-loaded magnetic microspheres were characterized for size, morphology, surface charge, and magnetization. The BSA encapsulation efficiency was determined by recovering albumin from the microspheres using dimethyl sulfoxide and 0.05N NaOH/0.5% SDS then quantifying with the Micro-BCA protein assay. BSA release profiles were also determined by the Micro-BCA protein assay. The microspheres had drug encapsulation efficiencies up to 90% depending on synthesis parameters. Particles were spherical with a smooth or porous surface having a size range less than 5 {mu}m. The surface charge (expressed as zeta potential) was near neutral, optimal for prolonged intravascular survival. The magnetization of these BSA loaded magnetic carriers was 2 to 6 emu/g, depending on the specific magnetic materials used during synthesis.

  4. Fundamental relations of mineral specific magnetic carriers for paleointensity determination

    Czech Academy of Sciences Publication Activity Database

    Kletetschka, Günther; Wieczorek, M. A.

    2017-01-01

    Roč. 272, November 2017 (2017), s. 44-49 ISSN 0031-9201 Institutional support: RVO:67985831 Keywords : Paleofield determination * TRM * Planetary magnetic anomalies * Néel’s theory of magnetism * Magnetic acquisition * Moon * Mars Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Particles and field physics Impact factor: 2.075, year: 2016

  5. Magnetically modified spent grain as a low-cost, biocompatible and smart carrier for enzyme immobilisation

    Czech Academy of Sciences Publication Activity Database

    Pospišková, K.; Šafařík, Ivo

    2013-01-01

    Roč. 93, č. 7 (2013), s. 1598-1602 ISSN 0022-5142 R&D Projects: GA ČR(CZ) GAP503/11/2263; GA MŠk LH12190 Institutional support: RVO:67179843 Keywords : magnetic fluid * spent grain * lipase * magnetic carrier * immobilisation Subject RIV: EI - Biotechnology ; Bionics Impact factor: 1.879, year: 2013

  6. Hybrid micro-particles as a magnetically-guidable decontaminant for cesium-eluted ash slurry

    Science.gov (United States)

    Namiki, Yoshihisa; Ueyama, Toshihiko; Yoshida, Takayuki; Watanabe, Ryoei; Koido, Shigeo; Namiki, Tamami

    2014-09-01

    Decontamination of the radioactive cesium that is widely dispersed owing to a nuclear power station accident and concentrated in fly ash requires an effective elimination system. Radioactive fly ash contains large amounts of water-soluble cesium that can cause severe secondary contamination and represents a serious health risk, yet its complete removal is complicated and difficult. Here it is shown that a new fine-powder formulation can be magnetically guided to eliminate cesium after being mixed with the ash slurry. This formulation, termed MagCE, consists of a ferromagnetic porous structure and alkaline- and salt-resistant nickel ferrocyanide. It has potent cesium-adsorption- and magnetic-separation-properties. Because of its resistance against physical and chemical attack such as with ash particles, as well as with the high pH and salt concentration of the ash slurry, MagCE simplifies the decontamination process without the need of the continued presence of the hazardous water-soluble cesium in the treated ash.

  7. The application of magnetic carriers in wastewater treatment

    Directory of Open Access Journals (Sweden)

    Hredzák Slavomír

    2000-09-01

    Full Text Available Ferromagnetic fluid is a kind of polyphase liquid, which is a stable colloid system of sufficiently small mono-domain magnetic particles covered by a film of surfactant and dispersed in a base liquid. Ferrofluids can be prepared in various base liquids such as water, hydrocarbons, mercury, etc., according to them utilisation. The basic properties of ferrofluids, i.e. the high magnetic polarisation of saturation and zero remanence predestine their application in various industrial branches including mineral processing and wastewater treatment.Wastewater treatment by the application of ferrofluids under magnetic field resides in the action of the field on the ferrofluid added to the oil substance. Strongly magnetically polarisable fluids enable to increase the magnetic susceptibility of oil substances to suitable level for their removal from water by a magnetic way. It was observed that the oil drop with the weight of 3.10 -3g and the ferrofluid concentration of 3% starts to move in the direction of the magnetic intensity growth at the minimal value of 105 A.m-1. It means that ordinary permanent magnet with the magnetic induction of 0.1 T causes the movement of the oil drops with a relatively small admixture of ferrofluid on the water level. This knowledge is very important for the design of magnetic filtration device which will be able to separate oil substances from water.Modification of magnetic properties of weakly magnetic materials by ferrofluids was also carried out in the case of magnetic filtration of water contaminated by fine grains of copper concentrate created by chalcopyrite. After admixing the ferrofluid into the suspension the recovery of mineral to the magnetic filter product ranges from 75 % to 98 % depending on the kind of ferrofluid and pH values. It was observed that in the case of water-based ferrofluid the recovery decreases with the increasing of pH value. But, on the other hand the increasing of pH value under the

  8. Molecular Magnetic Resonance Imaging of Angiogenesis In Vivo using Polyvalent Cyclic RGD-Iron Oxide Microparticle Conjugates

    Science.gov (United States)

    Melemenidis, Stavros; Jefferson, Andrew; Ruparelia, Neil; Akhtar, Asim M; Xie, Jin; Allen, Danny; Hamilton, Alastair; Larkin, James R; Perez-Balderas, Francisco; Smart, Sean C; Muschel, Ruth J; Chen, Xiaoyuan; Sibson, Nicola R; Choudhury, Robin P

    2015-01-01

    Angiogenesis is an essential component of tumour growth and, consequently, an important target both therapeutically and diagnostically. The cell adhesion molecule αvβ3 integrin is a specific marker of angiogenic vessels and the most prevalent vascular integrin that binds the amino acid sequence arginine-glycine-aspartic acid (RGD). Previous studies using RGD-targeted nanoparticles (20-50 nm diameter) of iron oxide (NPIO) for magnetic resonance imaging (MRI) of tumour angiogenesis, have identified a number of limitations, including non-specific extravasation, long blood half-life (reducing specific contrast) and low targeting valency. The aim of this study, therefore, was to determine whether conjugation of a cyclic RGD variant [c(RGDyK)], with enhanced affinity for αvβ3, to microparticles of iron oxide (MPIO) would provide a more sensitive contrast agent for imaging of angiogenic tumour vessels. Cyclic RGD [c(RGDyK)] and RAD [c(RADyK)] based peptides were coupled to 2.8 μm MPIO, and binding efficacy tested both in vitro and in vivo. Significantly greater specific binding of c(RGDyK)-MPIO to S-nitroso-n-acetylpenicillamine (SNAP)-stimulated human umbilical vein endothelial cells in vitro than PBS-treated cells was demonstrated under both static (14-fold increase; P agent in both tumour models (melanoma P < 0.001; colorectal P < 0.0001). Correspondingly, MPIO density per tumour volume assessed immunohistochemically was significantly greater for c(RGDyK)-MPIO than c(RADyK)-MPIO injected animals, in both melanoma (P < 0.05) and colorectal (P < 0.0005) tumours. In both cases, binding of c(RGDyK)-MPIO co-localised with αvβ3 expression. Comparison of RGD-targeted and dynamic contrast enhanced (DCE) MRI assessment of tumour perfusion indicated sensitivity to different vascular features. This study demonstrates specific binding of c(RGDyK)-MPIO to αvβ3 expressing neo-vessels, with marked and quantifiable contrast and rapid clearance of unbound particles from the

  9. Actinide separation of high-level waste using solvent extractants on magnetic microparticles

    International Nuclear Information System (INIS)

    Nunez, L.; Buchholz, B.A.; Kaminski, M.; Aase, S.B.; Brown, N.R.; Vandegrift, G.F.

    1994-01-01

    Polymeric-coated ferromagnetic particles with an absorbed layer of octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) diluted by tributyl phosphate (TBP) are being evaluated for application in the separation and the recovery of low concentrations of americium and plutonium from nuclear waste solutions. Due to their chemical nature, these extractants selectively complex americium and plutonium contaminants onto the particles, which can be recovered from the waste solution using a magnet. The effectiveness of the extractant-absorbed particles at removing transuranics (TRU) from simulated solutions and various nitric acid solutions was measured by gamma and liquid scintillation counting of plutonium and americium. The HNO 3 concentration range was 0.01 M to 6M. The partition coefficients (K d ) for various actinides at 2M HNO 3 were determined to be between 3,000 and 30,000. These values are larger than those projected for TRU recovery by traditional liquid/liquid extraction. Results from transmission electron microscopy indicated a large dependence of K d on relative magnetite location within the polymer and the polymer surface area. Energy disperse spectroscopy demonstrated homogeneous metal complexation on the polymer surface with no metal clustering. The radiolytic stability of the particles was determined by using 60 Co gamma irradiation under various conditions. The results showed that K d more strongly depends on the nitric acid dissolution rate of the magnetite than the gamma irradiation dose. Results of actinide separation from simulated high-level waste representative of that at various DOE sites are also discussed

  10. Magnetic susceptibility of free charge carriers in bismuth tellurides (Bi2Te3)

    International Nuclear Information System (INIS)

    Guha Thakurta, S.R.; Dutta, A.K.

    1977-01-01

    Principal magnetic susceptibilities of both p- and n-type Bi 2 Te 3 crystals have been measured over the range of temperature 90 deg K to 650 deg K. The observed susceptibilities are diamagnetic and temperature dependent. This temperature dependence has been attributed to the contribution of the free charge carriers to the susceptibilities. From the observed susceptibilities the carrier-susceptibilities have been separately obtained which are found to be paramagnetic. From the total carrier-susceptibilities, the susceptibilities of the carriers which are thermally liberated in the intrinsic region have been separated. From an analysis of the carrier-susceptibilities the band gap and its temperature coefficient have been found out and these compare favourably with those obtained from electrical measurements. (author)

  11. Slowing hot-carrier relaxation in graphene using a magnetic field

    Science.gov (United States)

    Plochocka, P.; Kossacki, P.; Golnik, A.; Kazimierczuk, T.; Berger, C.; de Heer, W. A.; Potemski, M.

    2009-12-01

    A degenerate pump-probe technique is used to investigate the nonequilibrium carrier dynamics in multilayer graphene. Two distinctly different dynamics of the carrier relaxation are observed. A fast relaxation (˜50fs) of the carriers after the initial effect of phase-space filling followed by a slower relaxation (˜4ps) due to thermalization. Both relaxation processes are less efficient when a magnetic field is applied at low temperatures which is attributed to the suppression of the electron-electron Auger scattering due to the nonequidistant Landau-level spacing of the Dirac fermions in graphene.

  12. Interaction of tricyclic drugs with copper phthalocyanine dye immobilized on magnetic carriers

    Czech Academy of Sciences Publication Activity Database

    Šafaříková, Miroslava; Šafařík, Ivo

    3(Suppl.2), - (2002), s. 188-191 ISSN 1473-2262. [International Conference on the Scientific and Clinical Applications of Magnetic Carriers /4./. Tallahassee, 09.05.2002-11.05.2002] R&D Projects: GA MŠk OC 523.80; GA AV ČR IBS6087204 Institutional research plan: CEZ:AV0Z6087904 Keywords : magnetic * tricyclic drugs * phthalocyanine Subject RIV: CE - Biochemistry

  13. High-throughput bioscreening system utilizing high-performance affinity magnetic carriers exhibiting minimal non-specific protein binding

    International Nuclear Information System (INIS)

    Hanyu, Naohiro; Nishio, Kosuke; Hatakeyama, Mamoru; Yasuno, Hiroshi; Tanaka, Toshiyuki; Tada, Masaru; Nakagawa, Takashi; Sandhu, Adarsh; Abe, Masanori; Handa, Hiroshi

    2009-01-01

    For affinity purification of drug target protein we have developed magnetic carriers, narrow in size distribution (184±9 nm), which exhibit minimal non-specific binding of unwanted proteins. The carriers were highly dispersed in aqueous solutions and highly resistant to organic solvents, which enabled immobilization of various hydrophobic chemicals as probes on the carrier surfaces. Utilizing the carriers we have automated the process of separation and purification of the target proteins that had been done by manual operation previously.

  14. Ballistic charge carrier transmission through graphene multi-barrier structures in uniform magnetic field

    International Nuclear Information System (INIS)

    Zubarev, A; Dragoman, D

    2014-01-01

    We investigate charge carrier transport in graphene multi-barrier structures placed in a uniform magnetic field. The transmission coefficient is found analytically by generalizing the transfer matrix method for the case of graphene regions subjected to a uniform magnetic field. The transmission coefficient through the structure can be modulated by varying the gate voltages, the magnetic field and/or the width of the gated regions. Such a configuration could be used in multiple-valued logic circuits, since it has several output states with discrete and easily selectable transmission/current values. (paper)

  15. Synthesis of Ferrofluids Made of Iron Oxide Nanoflowers: Interplay between Carrier Fluid and Magnetic Properties

    Directory of Open Access Journals (Sweden)

    Federico Spizzo

    2017-11-01

    Full Text Available Ferrofluids are nanomaterials consisting of magnetic nanoparticles that are dispersed in a carrier fluid. Their physical properties, and hence their field of application are determined by intertwined compositional, structural, and magnetic characteristics, including interparticle magnetic interactions. Magnetic nanoparticles were prepared by thermal decomposition of iron(III chloride hexahydrate (FeCl3·6H2O in 2-pyrrolidone, and were then dispersed in two different fluids, water and polyethylene glycol 400 (PEG. A number of experimental techniques (especially, transmission electron microscopy, Mössbauer spectroscopy and superconducting quantum interference device (SQUID magnetometry were employed to study both the as-prepared nanoparticles and the ferrofluids. We show that, with the adopted synthesis parameters of temperature and FeCl3 relative concentration, nanoparticles are obtained that mainly consist of maghemite and present a high degree of structural disorder and strong spin canting, resulting in a low saturation magnetization (~45 emu/g. A remarkable feature is that the nanoparticles, ultimately due to the presence of 2-pyrrolidone at their surface, are arranged in nanoflower-shape structures, which are substantially stable in water and tend to disaggregate in PEG. The different arrangement of the nanoparticles in the two fluids implies a different strength of dipolar magnetic interactions, as revealed by the analysis of their magnetothermal behavior. The comparison between the magnetic heating capacities of the two ferrofluids demonstrates the possibility of tailoring the performances of the produced nanoparticles by exploiting the interplay with the carrier fluid.

  16. Magnetically modified bacterial cellulose: A promising carrier for immobilization of affinity ligands, enzymes, and cells

    Energy Technology Data Exchange (ETDEWEB)

    Baldikova, Eva [Global Change Research Institute, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Pospiskova, Kristyna [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 27, 783 71 Olomouc (Czech Republic); Ladakis, Dimitrios; Kookos, Ioannis K. [Department of Chemical Engineering, University of Patras, 26504 Patras, Rio (Greece); Koutinas, Apostolis A. [Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, Athens 11855 (Greece); Safarikova, Mirka [Global Change Research Institute, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Department of Nanobiotechnology, Biology Centre, ISB, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Safarik, Ivo, E-mail: safarik@nh.cas.cz [Global Change Research Institute, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 27, 783 71 Olomouc (Czech Republic); Department of Nanobiotechnology, Biology Centre, ISB, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic)

    2017-02-01

    Bacterial cellulose (BC) produced by Komagataeibacter sucrofermentans was magnetically modified using perchloric acid stabilized magnetic fluid. Magnetic bacterial cellulose (MBC) was used as a carrier for the immobilization of affinity ligands, enzymes and cells. MBC with immobilized reactive copper phthalocyanine dye was an efficient adsorbent for crystal violet removal; the maximum adsorption capacity was 388 mg/g. Kinetic and thermodynamic parameters were also determined. Model biocatalysts, namely bovine pancreas trypsin and Saccharomyces cerevisiae cells were immobilized on MBC using several strategies including adsorption with subsequent cross-linking with glutaraldehyde and covalent binding on previously activated MBC using sodium periodate or 1,4-butanediol diglycidyl ether. Immobilized yeast cells retained approximately 90% of their initial activity after 6 repeated cycles of sucrose solution hydrolysis. Trypsin covalently bound after MBC periodate activation was very stable during operational stability testing; it could be repeatedly used for ten cycles of low molecular weight substrate hydrolysis without loss of its initial activity. - Highlights: • Bacterial cellulose was magnetically modified with magnetic fluid. • Magnetic cellulose is an efficient carrier for affinity ligands. • Enzymes and cells can be efficiently immobilized to magnetic cellulose.

  17. Microparticles in cardiovascular diseases

    NARCIS (Netherlands)

    VanWijk, Marja J.; VanBavel, E.; Sturk, A.; Nieuwland, R.

    2003-01-01

    Microparticles are membrane vesicles released from many different cell types. There are two mechanisms that can result in their formation, cell activation and apoptosis. In these two mechanisms, different pathways are involved in microparticle generation. Microparticle generation seems to be a well

  18. Antifungal Effect of a Dental Tissue Conditioner Containing Nystatin-Loaded Alginate Microparticles.

    Science.gov (United States)

    Kim, Hyun-Jin; Son, Jun Sik; Kwon, Tae-Yub

    2018-02-01

    In this in vitro study, nystatin-alginate microparticles were successfully fabricated to control the release of nystatin from a commercial dental tissue conditioner. These nystatin-alginate microparticles were spherical and had a slightly rough surface. The microparticles incorporated into the tissue conditioner were distributed homogeneously throughout the tissue conditioner matrix. The incorporation of the microparticles did not deteriorate the mechanical properties of the original material. The agar diffusion test results showed that the tissue conditioner containing the microparticles had a good antifungal effect against Candida albicans. The nystatin-alginate microparticles efficiently controlled the release of nystatin from the tissue conditioner matrix over the experimental period of 14 days. Moreover, the nystatin-alginate microparticles incorporated in the tissue conditioner showed effective antifungal function even at lower concentrations of nystatin. The current study suggests that the tissue conditioner containing the nystatin-alginate microparticle carrier system has potential as an effective antifungal material.

  19. Preparation and characterization of biodegradable magnetic carriers by single emulsion-solvent evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xianqiao [Departments of Neurology and Surgery (Neurosurgery), University of Chicago Pritzker School of Medicine, Chicago, IL (United States); Kaminski, Michael D. [Chemical Engineering Division, Argonne National Laboratory, Argonne, IL (United States); Riffle, Judy S. [Department of Chemistry, Virginia Tech, Blacksburg, VA (United States); Chen Haitao [Departments of Neurology and Surgery (Neurosurgery), University of Chicago Pritzker School of Medicine, Chicago, IL (United States); Torno, Michael [Departments of Neurology and Surgery (Neurosurgery), University of Chicago Pritzker School of Medicine, Chicago, IL (United States); Finck, Martha R. [Chemical Engineering Division, Argonne National Laboratory, Argonne, IL (United States); Taylor, LaToyia [Departments of Neurology and Surgery (Neurosurgery), University of Chicago Pritzker School of Medicine, Chicago, IL (United States); Rosengart, Axel J. [Departments of Neurology and Surgery (Neurosurgery), University of Chicago Pritzker School of Medicine, Chicago, IL (United States)]. E-mail: arosenga@uchicago.edu

    2007-04-15

    This paper describes a single emulsion-solvent evaporation protocol to prepare PEGylated biodegradable/biocompatible magnetic carriers by utilizing hydrophobic magnetite and a mixture of poly(D,L lactide-co-glycolide) (PLGA) and poly(lactic acid-block-polyethylene glycol) (PLA-PEG) (26:1 by mass) polymers. We characterized the magnetic microspheres in terms of morphology, composite microstructure, size and size distribution, and magnetic properties. Results show that the preparation produces magnetic microspheres with a good spherical morphology, small size (mean diameter of 1.2-1.5 {mu}m) by means of large size distributions, and magnetizations up to 20-30 emu/g of microspheres.

  20. Preparation and characterization of biodegradable magnetic carriers by single emulsion-solvent evaporation

    International Nuclear Information System (INIS)

    Liu Xianqiao; Kaminski, Michael D.; Riffle, Judy S.; Chen Haitao; Torno, Michael; Finck, Martha R.; Taylor, LaToyia; Rosengart, Axel J.

    2007-01-01

    This paper describes a single emulsion-solvent evaporation protocol to prepare PEGylated biodegradable/biocompatible magnetic carriers by utilizing hydrophobic magnetite and a mixture of poly(D,L lactide-co-glycolide) (PLGA) and poly(lactic acid-block-polyethylene glycol) (PLA-PEG) (26:1 by mass) polymers. We characterized the magnetic microspheres in terms of morphology, composite microstructure, size and size distribution, and magnetic properties. Results show that the preparation produces magnetic microspheres with a good spherical morphology, small size (mean diameter of 1.2-1.5 μm) by means of large size distributions, and magnetizations up to 20-30 emu/g of microspheres

  1. Microparticles from kidney-derived mesenchymal stem cells act as carriers of proangiogenic signals and contribute to recovery from acute kidney injury.

    Directory of Open Access Journals (Sweden)

    Hoon Young Choi

    Full Text Available We recently demonstrated the use of in vitro expanded kidney-derived mesenchymal stem cells (KMSC protected peritubular capillary endothelial cells in acute renal ischemia-reperfusion injury. Herein, we isolated and characterized microparticles (MPs from KMSC. We investigated their in vitro biologic effects on human endothelial cells and in vivo renoprotective effects in acute ischemia-reperfusion renal injury. MPs were isolated from the supernatants of KMSC cultured in anoxic conditions in serum-deprived media for 24 hours. KMSC-derived MPs demonstrated the presence of several adhesion molecules normally expressed on KMSC membranes, such as CD29, CD44, CD73, α4, 5, and 6 integrins. Quantitative real time PCR confirmed the presence of 3 splicing variants of VEGF-A (120, 164, 188, bFGF and IGF-1 in isolated MPs. MPs labeled with PKH26 red fluorescence dye were incorporated by cultured human umbilical vein endothelial cells (HUVEC via surface molecules such as CD44, CD29, and α4, 5, and 6 integrins. MP dose dependently improved in vitro HUVEC proliferation and promoted endothelial tube formation on growth factor reduced Matrigel. Moreover, apoptosis of human microvascular endothelial cell was inhibited by MPs. Administration of KMSC-derived MPs into mice with acute renal ischemia was followed by selective engraftment in ischemic kidneys and significant improvement in renal function. This was achieved by improving proliferation, of peritubular capillary endothelial cell and amelioration of peritubular microvascular rarefaction. Our results support the hypothesis that KMSC-derived MPs may act as a source of proangiogenic signals and confer renoprotective effects in ischemic kidneys.

  2. Microassembly using a Cluster of Paramagnetic Microparticles

    NARCIS (Netherlands)

    Khalil, I.S.M.; Brink, F.V; Sardan Sukas, Ö.; Misra, Sarthak

    2013-01-01

    We use a cluster of paramagnetic microparticles to carry out a wireless two-dimensional microassembly operation. A magnetic-based manipulation system is used to control the motion of the cluster under the influence of the applied magnetic fields. Wireless motion control of the cluster is implemented

  3. Ultrafast Control of Magnetism in Ferromagnetic Semiconductors via Photoexcited Transient Carriers

    Energy Technology Data Exchange (ETDEWEB)

    Cotoros, Ingrid A. [Univ. of California, Berkeley, CA (United States)

    2008-12-01

    The field of spintronics offers perspectives for seamless integration of coupled and inter-tunable electrical and magnetic properties in a single device. For integration of the spin degree of freedom with current electronic technology, new semiconductors are needed that show electrically-tunable magnetic properties at room temperature and above. Dilute magnetic semiconductors derived from III-V compounds, like GaMnAs and InMnAs, show coupled and tunable magnetic, transport, and optical properties, due to the fact that their ferromagnetism is hole-mediated. These unconventional materials are ideal systems for manipulating the magnetic order by changing the carrier polarization, population density, and energy band distribution of the complementary subsystem of holes. This is the main theme we cover in this thesis. In particular, we develop a unique setup by use of ultraviolet pump, near-infrared probe femtosecond laser pulses, that allows for magneto-optical Kerr effect (MOKE) spectroscopy experiments. We photo-excite transient carriers in our samples, and measure the induced transient magnetization dynamics. One set of experiments performed allowed us to observe for the first time enhancement of the ferromagnetic order in GaMnAs, on an ultrafast time scale of hundreds of picoseconds. The corresponding transient increase of Curie temperature (Tc, the temperature above which a ferromagnetic material loses its permanent magnetism) of about 1 K for our experimental conditions is a very promising result for potential spintronics applications, especially since it is seconded by observation of an ultrafast ferromagnetic to paramagnetic phase transition above Tc. In a different set of experiments, we "write" the magnetization in a particular orientation in the sample plane. Using an ultrafast scheme, we alter the distribution of holes in the system and detect signatures of the particular memory state in the subsequent magnetization dynamics, with unprecedented hundreds of

  4. Stepping Stone Mechanism: Carrier-Free Long-Range Magnetism Mediated by Magnetized Cation States in Quintuple Layer

    Science.gov (United States)

    Chan, Chunkai; Zhang, Xiaodong; Zhang, Yiou; Tse, Kinfai; Deng, Bei; Zhang, Jingzhao; Zhu, Junyi

    2018-01-01

    The long-range magnetism observed in group-V tellurides quintuple layers is the only working example of carrier-free dilute magnetic semiconductors (DMS), whereas the physical mechanism is unclear, except the speculation on the band topology enhanced van Vleck paramagnetism. Based on DFT calculations, we find a stable long-range ferromagnetic order in a single quintuple layer of Cr-doped Bi2Te3 or Sb2Te3, with the dopant separation more than 9 Å. This configuration is the global energy minimum among all configurations. Different from the conventional super exchange theory, the magnetism is facilitated by the lone pair derived anti-bonding states near the cations. Such anti-bonding states work as stepping stones merged in the electron sea and conduct magnetism. Further, spin orbit coupling induced band inversion is found to be insignificant in the magnetism. Therefore, our findings directly dismiss the common misbelief that band topology is the only factor that enhances the magnetism. We further demonstrate that removal of the lone pair derived states destroys the long-range magnetism. This novel mechanism sheds light on the fundamental understanding of long-range magnetism and may lead to discoveries of new classes of DMS. Supported by Chinese University of Hong Kong (CUHK) under Grant No 4053084, University Grants Committee of Hong Kong under Grant No 24300814, and the Start-up Funding of CUHK.

  5. Microfluidic production of polymeric functional microparticles

    Science.gov (United States)

    Jiang, Kunqiang

    This dissertation focuses on applying droplet-based microfluidics to fabricate new classes of polymeric microparticles with customized properties for various applications. The integration of microfluidic techniques with microparticle engineering allows for unprecedented control over particle size, shape, and functional properties. Specifically, three types of microparticles are discussed here: (1) Magnetic and fluorescent chitosan hydrogel microparticles and their in-situ assembly into higher-order microstructures; (2) Polydimethylsiloxane (PDMS) microbeads with phosphorescent properties for oxygen sensing; (3) Macroporous microparticles as biological immunosensors. First, we describe a microfluidic approach to generate monodisperse chitosan hydrogel microparticles that can be further connected in-situ into higher-order microstructures. Microparticles of the biopolymer chitosan are created continuously by contacting an aqueous solution of chitosan at a microfluidic T-junction with a stream of hexadecane containing a nonionic detergent, followed by downstream crosslinking of the generated droplets by a ternary flow of glutaraldehyde. Functional properties of the microparticles can be easily varied by introducing payloads such as magnetic nanoparticles and/or fluorescent dyes into the chitosan solution. We then use these prepared microparticles as "building blocks" and assemble them into high ordered microstructures, i.e. microchains with controlled geometry and flexibility. Next, we describe a new approach to produce monodisperse microbeads of PDMS using microfluidics. Using a flow-focusing configuration, a PDMS precursor solution is dispersed into microdroplets within an aqueous continuous phase. These droplets are collected and thermally cured off-chip into soft, solid microbeads. In addition, our technique allows for direct integration of payloads, such as an oxygen-sensitive porphyrin dye, into the PDMS microbeads. We then show that the resulting dye

  6. Observations of the Earth's magnetic field from the shuttle: Using the Spartan carrier as a magnetic survey tool

    Science.gov (United States)

    Webster, W. J., Jr.

    1986-01-01

    The shuttle-deployed and recovered Spartan shows promise as an inexpensive and simple support module for potential field measurements. The results of a preliminary engineering study on the applications of the Spartan carrier to magnetic measurements shows: (1) Extension of the mission duration to as long as 7 days is feasible but requires more reconfiguration of the internal systems; (2) On-board recording of Global Positioning System signals will provide position determination with an accuracy consistent with the most severe requirements; and (3) Making Spartan a magnetically clean spacecraft is straight forward but requires labor-intensive modifications to both the data and power systems. As a magnetic survey tool, Spartan would allow surveys at regularly spaced intervals and could make quick-reaction surveys at times of instability in the secular variation.

  7. Multimodal magnetic nano-carriers for cancer treatment: Challenges and advancements

    Energy Technology Data Exchange (ETDEWEB)

    Aadinath, W.; Ghosh, Triroopa; Anandharamakrishnan, C., E-mail: anandharam@cftri.res.in

    2016-03-01

    Iron oxide nanoparticles (IONPs) have been a propitious topic for cancer treatment in recent years because of its multifunctional theranostic applications under magnetic field. Two such widely used applications in cancer biology are gradient magnetic field guided targeting and alternative magnetic field (AMF) induced local hyperthermia. Gradient magnetic field guided targeting is a mode of active targeting of therapeutics conjugated with iron oxide nanoparticles. These particles also dissipate heat in presence of AMF which causes thermal injury to the cells of interest, for example tumour cells and subsequent death. Clinical trials divulge the feasibility of such magnetic nano-carrier as a promising candidate in cancer biology. However, these techniques need further investigations to curtail certain limitations manifested. Recent progresses in response have shrunken the barricade to certain extent. In this context, principles, challenges associated with these applications and recent efforts made in response will be discussed. - Highlights: • Iron oxide nanoparticles offer various modalities in the field of cancer theranostics. • Magnetic field guided targeting and local hyperthermia are two well known modalities in cancer therapy. • These techniques need further investigations to curtail certain limitations manifested. • This review emphasizes the recent efforts carried out to counteract the drawbacks.

  8. Preparation of alginate coated chitosan microparticles for vaccine delivery

    Directory of Open Access Journals (Sweden)

    Wei YuQuan

    2008-11-01

    Full Text Available Abstract Background Absorption of antigens onto chitosan microparticles via electrostatic interaction is a common and relatively mild process suitable for mucosal vaccine. In order to increase the stability of antigens and prevent an immediate desorption of antigens from chitosan carriers in gastrointestinal tract, coating onto BSA loaded chitosan microparticles with sodium alginate was performed by layer-by-layer technology to meet the requirement of mucosal vaccine. Results The prepared alginate coated BSA loaded chitosan microparticles had loading efficiency (LE of 60% and loading capacity (LC of 6% with mean diameter of about 1 μm. When the weight ratio of alginate/chitosan microparticles was greater than 2, the stable system could be obtained. The rapid charge inversion of BSA loaded chitosan microparticles (from +27 mv to -27.8 mv was observed during the coating procedure which indicated the presence of alginate layer on the chitosan microparticles surfaces. According to the results obtained by scanning electron microscopy (SEM, the core-shell structure of BSA loaded chitosan microparticles was observed. Meanwhile, in vitro release study indicated that the initial burst release of BSA from alginate coated chitosan microparticles was lower than that observed from uncoated chitosan microparticles (40% in 8 h vs. about 84% in 0.5 h. SDS-polyacrylamide gel electrophoresis (SDS-PAGE assay showed that alginate coating onto chitosan microparticles could effectively protect the BSA from degradation or hydrolysis in acidic condition for at least 2 h. The structural integrity of alginate modified chitosan microparticles incubated in PBS for 24 h was investigated by FTIR. Conclusion The prepared alginate coated chitosan microparticles, with mean diameter of about 1 μm, was suitable for oral mucosal vaccine. Moreover, alginate coating onto the surface of chitosan microparticles could modulate the release behavior of BSA from alginate coated chitosan

  9. Biodistribution of doxorubicin and nanostructured ferrocarbon carrier particles in organism during magnetically controlled drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, Anatoly A.; Filippov, Victor I.; Nikolskaya, Tatiana A. [Institute of Biochemical Physics, Russian Academy of Sciences, Kosygin St. 4, Moscow 119991 (Russian Federation); Budko, Andrei P. [Oncological Center, Russian Academy of Medical Sciences, Moscow (Russian Federation); Kovarskii, Alexander L. [Institute of Biochemical Physics, Russian Academy of Sciences, Kosygin St. 4, Moscow 119991 (Russian Federation); Zontov, Sergei V. [Oncological Center, Russian Academy of Medical Sciences, Moscow (Russian Federation); Kogan, Boris Ya. [Institute of Biochemical Physics, Russian Academy of Sciences, Kosygin St. 4, Moscow 119991 (Russian Federation); Kuznetsov, Oleg A. [Institute of Biochemical Physics, Russian Academy of Sciences, Kosygin St. 4, Moscow 119991 (Russian Federation)], E-mail: kuznetsov_oa@yahoo.com

    2009-05-15

    Biodistribution of doxorubicin and ferrocarbon carrier particles in organism during and after magnetically controlled anti-tumor drug delivery and deposition was studied. Animal tests show high concentration of the cytostatic drug in the target zone, while its concentration is three orders of magnitude lower in bloodstream and other organs. A significant depot of the drug remains on the deposited particles days after the procedure. Macrophages actively phagocytose the ferrocarbon (FeC) particles and remain viable long enough to carry them to the lymph nodes.

  10. Biodistribution of doxorubicin and nanostructured ferrocarbon carrier particles in organism during magnetically controlled drug delivery

    International Nuclear Information System (INIS)

    Kuznetsov, Anatoly A.; Filippov, Victor I.; Nikolskaya, Tatiana A.; Budko, Andrei P.; Kovarskii, Alexander L.; Zontov, Sergei V.; Kogan, Boris Ya.; Kuznetsov, Oleg A.

    2009-01-01

    Biodistribution of doxorubicin and ferrocarbon carrier particles in organism during and after magnetically controlled anti-tumor drug delivery and deposition was studied. Animal tests show high concentration of the cytostatic drug in the target zone, while its concentration is three orders of magnitude lower in bloodstream and other organs. A significant depot of the drug remains on the deposited particles days after the procedure. Macrophages actively phagocytose the ferrocarbon (FeC) particles and remain viable long enough to carry them to the lymph nodes.

  11. Simulations of magnetic capturing of drug carriers in the brain vascular system

    Energy Technology Data Exchange (ETDEWEB)

    Kenjeres, S., E-mail: S.Kenjeres@tudelft.nl [Department of Multi-Scale Physics, Faculty of Applied Sciences, J.M. Burgerscentre for Fluid Dynamics, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft (Netherlands); Righolt, B.W. [Department of Multi-Scale Physics, Faculty of Applied Sciences, J.M. Burgerscentre for Fluid Dynamics, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft (Netherlands)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Blood flow and magnetic particles distributions in the brain vascular system simulated. Black-Right-Pointing-Pointer Numerical mesh generated from raw MRI images. Black-Right-Pointing-Pointer Significant increase in local capturing of magnetic particles obtained. Black-Right-Pointing-Pointer Promising technique for localised non-invasive treatment of brain tumours. - Abstract: The present paper reports on numerical simulations of blood flow and magnetic drug carrier distributions in a complex brain vascular system. The blood is represented as a non-Newtonian fluid by the generalised power law. The Lagrangian tracking of the double-layer spherical particles is performed to estimate particle deposition under influence of imposed magnetic field gradients across arterial walls. Two situations are considered: neutral (magnetic field off) and active control (magnetic field on) case. The double-layer spherical particles that mimic a real medical drug are characterised by two characteristic diameters - the outer one and the inner one of the magnetic core. A numerical mesh of the brain vascular system consisting of multi-branching arteries is generated from raw MRI scan images of a patient. The blood is supplied through four main inlet arteries and the entire vascular system includes more than 30 outlets, which are modelled by Murray's law. The no-slip boundary condition is applied for velocity components along the smooth and rigid arterial walls. Numerical simulations revealed detailed insights into blood flow patterns, wall-shear-stress and local particle deposition efficiency along arterial walls. It is demonstrated that magnetically targeted drug delivery significantly increased the particle capturing efficiency in the pre-defined regions. This feature can be potentially useful for localised, non-invasive treatment of brain tumours.

  12. Physics of microparticle acoustophoresis

    DEFF Research Database (Denmark)

    Barnkob, Rune

    2012-01-01

    of microparticle acoustophoresis and to develop methods for future advancement of its use. Throughout the work on this thesis the author and co-workers1 have studied the physics of microparticle acoustophoresis by comparing quantitative measurements to a theoretical framework consisting of existing hydrodynamic...

  13. Sensitized charge carrier injection into organic crystals studied by isotope effects in weak magnetic fields

    International Nuclear Information System (INIS)

    Bube, W.; Michel-Beyerle, M.E.; Haberkorn, R.; Steffens, E.

    1977-01-01

    The magnetic field (H approximately 50 Oe) dependence of the rhodamine sensitized triplet exciton density in anthracene crystals is influenced by isotopic substitution. This confirms the hyperfine interaction as mechanism explaining the change of the spin multiplicity in the initially formed singlet state of the radical pair. The isotope effect occurs in the sensitizing dye ( 14 N/ 15 N) rather than at the molecular site of the injected charge within the crystal. This can be understood in terms of the high hopping frequency of the charge carriers as compared to the time constant of the hyperfine induced singlet-triplet transition. Since the dye molecules adsorb in an oriented fashion, the angular dependence of the magnetic field modulation of the triplet exciton density can be interpreted without assuming any additional interactions. (Auth.)

  14. Restructuring of microparticles

    International Nuclear Information System (INIS)

    Lameiras, F.S.; Santos, A.M.M. dos

    1992-01-01

    Experimental grain sizes distribution of sintered (U,Gd)O 2 pellets were analysed according to the model of Lameiras for microparticles restructuring. This model, which includes the grain growth and Ostwald ripening phenomena, assumes that the microparticles restructuring is governed by two fundamental principles: minimization of the interface energy and uniformization of its distribution in space. It is also, assumed that the interface energy is stored in the grain boundaries, triple lines and quadruple points. The minimization of the interface energy can be done through three ways independent of each other: diminishing of the number of microparticles, alteration of the size distribution and alteration of the form distribution. The uniformization of the spatial distribution of the interface energy can be done through two ways also independent of each other: tendency to an uniform spatial distribution of microparticles and tendency to an uniform distribution of the interface energy per microparticle. The model accords well with these experimental data. (author)

  15. Fragile X syndrome: a pilot proton magnetic resonance spectroscopy study in premutation carriers

    LENUS (Irish Health Repository)

    Hallahan, Brian P

    2012-08-30

    AbstractPurposeThere is increasing evidence that neurodevelopmental differences in people with Fragile X syndrome (FraX) may be explained by differences in glutamatergic metabolism. Premutation carriers of FraX were originally considered to be unaffected although several recent reports demonstrate neuroanatomical, cognitive, and emotional differences from controls. However there are few studies on brain metabolism in premutation carriers of FraX.MethodsWe used proton magnetic resonance spectroscopy to compare neuronal integrity of a number of brain metabolites including N-Acetyl Aspartate, Creatine + Phosphocreatinine, Choline, myoInositol, and Glutamate containing substances (Glx) in 17 male premutation carriers of FraX and 16 male healthy control individuals.ResultsThere was no significant between-group difference in the concentration of any measured brain metabolites. However there was a differential increase in N-acetyl aspartate with aging in premutation FraX individuals compared to controls.ConclusionsThis is the first 1 H-MRS study to examine premutation FraX individuals. Although we demonstrated no difference in the concentration of any of the metabolites examined between the groups, this may be due to the large age ranges included in the two samples. The differential increase in NAA levels with aging may reflect an abnormal synaptic pruning process.

  16. Imaging based agglutination measurement of magnetic micro-particles on a lab-on-a-disk platform

    DEFF Research Database (Denmark)

    Wantiya, P.; Burger, Robert; Alstrøm, Tommy Sonne

    2014-01-01

    In this work we present a magnetic micro beads based agglutination assay on a centrifugal microfluidic platform. An imaging based method is used to quantify bead agglutination and measure the concentration of antibodies or C-reactive protein in solution.......In this work we present a magnetic micro beads based agglutination assay on a centrifugal microfluidic platform. An imaging based method is used to quantify bead agglutination and measure the concentration of antibodies or C-reactive protein in solution....

  17. Cardiac pathologies in female carriers of Duchenne muscular dystrophy assessed by cardiovascular magnetic resonance imaging

    International Nuclear Information System (INIS)

    Schelhorn, Juliane; Schemuth, Haemi; Nensa, Felix; Nassenstein, Kai; Forsting, Michael; Schlosser, Thomas; Schoenecker, Anne; Neudorf, Ulrich; Schara, Ulrike

    2015-01-01

    Duchenne muscular dystrophy (DMD) is the most common and severe dystrophinopathy. DMD carriers rarely present with clinical symptoms, but may suffer from cardiac involvement. Because echocardiographic findings are inconsistent and cardiac magnetic resonance imaging (CMRI) data are limited, this study sought to investigate asymptomatic carriers for cardiac abnormalities using CMRI. Fifteen genetically confirmed DMD carriers (age, 32.3 ± 10.2 years) were prospectively examined on a 1.5T MR system. Cine, T2, and late-gadolinium-enhanced (LGE) images were acquired, and were evaluated in consensus by two experienced readers. Left ventricular (LV) parameters were analysed semiautomatically, normalized to BSA. Normalized LV end-diastolic volume was increased in 7 % (73.7 ± 16.8 ml/m 2 ; range, 48-116 ml/m 2 ) and normalized LV end-systolic volume in 20 % (31.5 ± 13.3 ml/m 2 ; range, 15-74 ml/m 2 ). EF was reduced in 33 % (58.4 ± 7.6 %; range, 37-69 %) and normalized LV myocardial mass in 80 % (40.5 ± 6.8 g/m 2 ; range, 31-55 g/m 2 ). In 80 %, regional myocardial thinning was detected in more than one segment. In 13 % and 40 %, apical-lateral accentuation of LV non-compaction was present. LGE was found in 60 % (midmyocardial inferolateral accentuation). Given the high frequency of cardiac pathologies detected by CMRI, regular cardiac risk assessment is advisable for DMD carriers. Besides clinical examination, CMRI is an excellent tool for this purpose. (orig.)

  18. Cardiac pathologies in female carriers of Duchenne muscular dystrophy assessed by cardiovascular magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Schelhorn, Juliane; Schemuth, Haemi; Nensa, Felix; Nassenstein, Kai; Forsting, Michael; Schlosser, Thomas [University Hospital Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany); Schoenecker, Anne; Neudorf, Ulrich [University Hospital Essen, Department of Pediatric Cardiology, Essen (Germany); Schara, Ulrike [University Hospital Essen, Department of Pediatric Neurology, Essen (Germany)

    2015-10-15

    Duchenne muscular dystrophy (DMD) is the most common and severe dystrophinopathy. DMD carriers rarely present with clinical symptoms, but may suffer from cardiac involvement. Because echocardiographic findings are inconsistent and cardiac magnetic resonance imaging (CMRI) data are limited, this study sought to investigate asymptomatic carriers for cardiac abnormalities using CMRI. Fifteen genetically confirmed DMD carriers (age, 32.3 ± 10.2 years) were prospectively examined on a 1.5T MR system. Cine, T2, and late-gadolinium-enhanced (LGE) images were acquired, and were evaluated in consensus by two experienced readers. Left ventricular (LV) parameters were analysed semiautomatically, normalized to BSA. Normalized LV end-diastolic volume was increased in 7 % (73.7 ± 16.8 ml/m{sup 2}; range, 48-116 ml/m{sup 2}) and normalized LV end-systolic volume in 20 % (31.5 ± 13.3 ml/m{sup 2}; range, 15-74 ml/m{sup 2}). EF was reduced in 33 % (58.4 ± 7.6 %; range, 37-69 %) and normalized LV myocardial mass in 80 % (40.5 ± 6.8 g/m{sup 2}; range, 31-55 g/m{sup 2}). In 80 %, regional myocardial thinning was detected in more than one segment. In 13 % and 40 %, apical-lateral accentuation of LV non-compaction was present. LGE was found in 60 % (midmyocardial inferolateral accentuation). Given the high frequency of cardiac pathologies detected by CMRI, regular cardiac risk assessment is advisable for DMD carriers. Besides clinical examination, CMRI is an excellent tool for this purpose. (orig.)

  19. A visual dual-aptamer logic gate for sensitive discrimination of prion diseases-associated isoform with reusable magnetic microparticles and fluorescence quantum dots.

    Science.gov (United States)

    Xiao, Sai Jin; Hu, Ping Ping; Chen, Li Qiang; Zhen, Shu Jun; Peng, Li; Li, Yuan Fang; Huang, Cheng Zhi

    2013-01-01

    Molecular logic gates, which have attracted increasing research interest and are crucial for the development of molecular-scale computers, simplify the results of measurements and detections, leaving the diagnosis of disease either "yes" or "no". Prion diseases are a group of fatal neurodegenerative disorders that happen in human and animals. The main problem with a diagnosis of prion diseases is how to sensitively and selectively discriminate and detection of the minute amount of PrP(Res) in biological samples. Our previous work had demonstrated that dual-aptamer strategy could achieve highly sensitive and selective discrimination and detection of prion protein (cellular prion protein, PrP(C), and the diseases associated isoform, PrP(Res)) in serum and brain. Inspired by the advantages of molecular logic gate, we further conceived a new concept for dual-aptamer logic gate that responds to two chemical input signals (PrP(C) or PrP(Res) and Gdn-HCl) and generates a change in fluorescence intensity as the output signal. It was found that PrP(Res) performs the "OR" logic operation while PrP(C) performs "XOR" logic operation when they get through the gate consisted of aptamer modified reusable magnetic microparticles (MMPs-Apt1) and quantum dots (QDs-Apt2). The dual-aptamer logic gate simplifies the discrimination results of PrP(Res), leaving the detection of PrP(Res) either "yes" or "no". The development of OR logic gate based on dual-aptamer strategy and two chemical input signals (PrP(Res) and Gdn-HCl) is an important step toward the design of prion diseases diagnosis and therapy systems.

  20. A visual dual-aptamer logic gate for sensitive discrimination of prion diseases-associated isoform with reusable magnetic microparticles and fluorescence quantum dots.

    Directory of Open Access Journals (Sweden)

    Sai Jin Xiao

    Full Text Available Molecular logic gates, which have attracted increasing research interest and are crucial for the development of molecular-scale computers, simplify the results of measurements and detections, leaving the diagnosis of disease either "yes" or "no". Prion diseases are a group of fatal neurodegenerative disorders that happen in human and animals. The main problem with a diagnosis of prion diseases is how to sensitively and selectively discriminate and detection of the minute amount of PrP(Res in biological samples. Our previous work had demonstrated that dual-aptamer strategy could achieve highly sensitive and selective discrimination and detection of prion protein (cellular prion protein, PrP(C, and the diseases associated isoform, PrP(Res in serum and brain. Inspired by the advantages of molecular logic gate, we further conceived a new concept for dual-aptamer logic gate that responds to two chemical input signals (PrP(C or PrP(Res and Gdn-HCl and generates a change in fluorescence intensity as the output signal. It was found that PrP(Res performs the "OR" logic operation while PrP(C performs "XOR" logic operation when they get through the gate consisted of aptamer modified reusable magnetic microparticles (MMPs-Apt1 and quantum dots (QDs-Apt2. The dual-aptamer logic gate simplifies the discrimination results of PrP(Res, leaving the detection of PrP(Res either "yes" or "no". The development of OR logic gate based on dual-aptamer strategy and two chemical input signals (PrP(Res and Gdn-HCl is an important step toward the design of prion diseases diagnosis and therapy systems.

  1. Obtain and characterization of chitosan / propranolol microparticles by spray drying

    International Nuclear Information System (INIS)

    Nascimento, Ednaldo G. do; Silva Junior, Arnobio A. da; Santos, Katia S.C.R. dos

    2015-01-01

    The study investigated the application of chitosan microparticles as carriers into hard gelatin capsule containing propranolol, evaluating the variability of the molecular weight and the chitosan particles by spray drying. The formulations were characterized by average weight, dosing unit dose uniformity and dissolution profile according to the pharmacopoeia. While the microparticles were characterized by Fourier transformed infrared spectroscopy, scanning electron microscopy and X-ray diffraction. The results showed that chitosan microparticles obtained without the drug and then physically mixed with propranolol promoted a modified release 85% of the drug after 5 hours. While, chitosan microparticles sprayed with propranolol released only 55% at 5 hours is presented both as a modified release system. Samples of dried chitosan showed up amorphous and homogeneous and spherical morphology. (author)

  2. Microparticle Flow Sensor

    Science.gov (United States)

    Morrison, Dennis R.

    2005-01-01

    The microparticle flow sensor (MFS) is a system for identifying and counting microscopic particles entrained in a flowing liquid. The MFS includes a transparent, optoelectronically instrumented laminar-flow chamber (see figure) and a computer for processing instrument-readout data. The MFS could be used to count microparticles (including micro-organisms) in diverse applications -- for example, production of microcapsules, treatment of wastewater, pumping of industrial chemicals, and identification of ownership of liquid products.

  3. Magnetic graphene oxide as a carrier for targeted delivery of chemotherapy drugs in cancer therapy

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Ya-Shu [Department of Chemical and Materials Engineering, Chang Gung University, Kwei-San, Taoyuan 33302, Taiwan, ROC (China); Lu, Yu-Jen [Department of Neurosurgery, Chang Gung Memorial Hospital, Kwei-San, Taoyuan 33305, Taiwan, ROC (China); Chen, Jyh-Ping, E-mail: jpchen@mail.cgu.edu.tw [Department of Chemical and Materials Engineering, Chang Gung University, Kwei-San, Taoyuan 33302, Taiwan, ROC (China); Department of Plastic and Reconstructive Surgery and Craniofacial Research Center, Chang Gung Memorial Hospital, Kwei-San, Taoyuan 33305, Taiwan, ROC (China); Graduate Institute of Health Industry and Technology, Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Kwei-San, Taoyuan 33302, Taiwan, ROC (China); Department of Materials Engineering, Ming Chi University of Technology, Tai-Shan, New Taipei City 24301, Taiwan, ROC (China)

    2017-04-01

    A magnetic targeted functionalized graphene oxide (GO) complex is constituted as a nanocarrier for targeted delivery and pH-responsive controlled release of chemotherapy drugs to cancer cells. Magnetic graphene oxide (mGO) was prepared by chemical co-precipitation of Fe{sub 3}O{sub 4} magnetic nanoparticles on GO nano-platelets. The mGO was successively modified by chitosan and mPEG-NHS through covalent bindings to synthesize mGOC-PEG. The polyethylene glycol (PEG) moiety is expected to prolong the circulation time of mGO by reducing the reticuloendothelial system clearance. Irinotecan (CPT-11) or doxorubicin (DOX) was loaded to mGOC-PEG through π-π stacking interactions for magnetic targeted delivery of the cancer chemotherapy drug. The best values of loading efficiency and loading content of CPT-11 were 54% and 2.7% respectively; whereas for DOX, they were 65% and 393% The pH-dependent drug release profile was further experimented at different pHs, in which ~60% of DOX was released at pH 5.4 and ~10% was released at pH 7.4. In contrast, ~90% CPT-11 was released at pH 5.4 and ~70% at pH 7.4. Based on the drug loading and release characteristics, mGOC-PEG/DOX was further chosen for in vitro cytotoxicity tests against U87 human glioblastoma cell line. The IC50 value of mGOC-PEG/DOX was found to be similar to that of free DOX but was reduced dramatically when subject to magnetic targeting. It is concluded that with the high drug loading and pH-dependent drug release properties, mGOC-PEG will be a promising drug carrier for targeted delivery of chemotherapy drugs in cancer therapy. - Highlights: • mGO was prepared by chemical co-precipitation of Fe{sub 3}O{sub 4} MNP on GO nano-platelets. • mGO was further modified by chitosan and mPEG-NHS to synthesize mGOC-PEG. • mGOC-PEG showed higher drug loading of doxorubicin (DOX) than irinotecan. • mGOC-PEG showed pH-responsive controlled release of chemotherapy drugs. • Magnetic targeting enhanced cytotoxicity of

  4. Magnetic graphene oxide as a carrier for targeted delivery of chemotherapy drugs in cancer therapy

    International Nuclear Information System (INIS)

    Huang, Ya-Shu; Lu, Yu-Jen; Chen, Jyh-Ping

    2017-01-01

    A magnetic targeted functionalized graphene oxide (GO) complex is constituted as a nanocarrier for targeted delivery and pH-responsive controlled release of chemotherapy drugs to cancer cells. Magnetic graphene oxide (mGO) was prepared by chemical co-precipitation of Fe 3 O 4 magnetic nanoparticles on GO nano-platelets. The mGO was successively modified by chitosan and mPEG-NHS through covalent bindings to synthesize mGOC-PEG. The polyethylene glycol (PEG) moiety is expected to prolong the circulation time of mGO by reducing the reticuloendothelial system clearance. Irinotecan (CPT-11) or doxorubicin (DOX) was loaded to mGOC-PEG through π-π stacking interactions for magnetic targeted delivery of the cancer chemotherapy drug. The best values of loading efficiency and loading content of CPT-11 were 54% and 2.7% respectively; whereas for DOX, they were 65% and 393% The pH-dependent drug release profile was further experimented at different pHs, in which ~60% of DOX was released at pH 5.4 and ~10% was released at pH 7.4. In contrast, ~90% CPT-11 was released at pH 5.4 and ~70% at pH 7.4. Based on the drug loading and release characteristics, mGOC-PEG/DOX was further chosen for in vitro cytotoxicity tests against U87 human glioblastoma cell line. The IC50 value of mGOC-PEG/DOX was found to be similar to that of free DOX but was reduced dramatically when subject to magnetic targeting. It is concluded that with the high drug loading and pH-dependent drug release properties, mGOC-PEG will be a promising drug carrier for targeted delivery of chemotherapy drugs in cancer therapy. - Highlights: • mGO was prepared by chemical co-precipitation of Fe 3 O 4 MNP on GO nano-platelets. • mGO was further modified by chitosan and mPEG-NHS to synthesize mGOC-PEG. • mGOC-PEG showed higher drug loading of doxorubicin (DOX) than irinotecan. • mGOC-PEG showed pH-responsive controlled release of chemotherapy drugs. • Magnetic targeting enhanced cytotoxicity of m

  5. DNA tagged microparticles

    Science.gov (United States)

    Farquar, George Roy; Leif, Roald N; Wheeler, Elizabeth

    2015-05-05

    A simulant that includes a carrier and DNA encapsulated in the carrier. Also a method of making a simulant including the steps of providing a carrier and encapsulating DNA in the carrier to produce the simulant.

  6. Procedure for radiotracer labelling of carbon microparticles

    International Nuclear Information System (INIS)

    Kallay, Z.; Soltes, L.; Novak, I.; Trnovec, T.; Berek, D.

    1988-01-01

    A method is suggested for the labelling of carbon microparticles with radioisotopes. A carbon precursor is selected from the group of polymers including phenol-formaldehyde bitumens, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, urea-formaldehyde or epoxy bitumens, and polysaccharides. A monodisperse fraction of the porous precursor is saturated with a solution of a salt of the radioisotope, and the carrier solvent is removed by evaporation at 360-420 K. The impregnated precursor is subsequently pyrolyzed at 870-1000 K. This method can find application in the preparation of radiactively labelled microparticles used for examining changes in the function of the cardiovascular system in experimental medicine, pharmacology, physiology and endocrinology. (P.A.)

  7. Carrier relaxation in (In,Ga)As quantum dots with magnetic field-induced anharmonic level structure

    Energy Technology Data Exchange (ETDEWEB)

    Kurtze, H.; Bayer, M. [Experimentelle Physik 2, TU Dortmund, D-44221 Dortmund (Germany)

    2016-07-04

    Sophisticated models have been worked out to explain the fast relaxation of carriers into quantum dot ground states after non-resonant excitation, overcoming the originally proposed phonon bottleneck. We apply a magnetic field along the quantum dot heterostructure growth direction to transform the confined level structure, which can be approximated by a Fock–Darwin spectrum, from a nearly equidistant level spacing at zero field to strong anharmonicity in finite fields. This changeover leaves the ground state carrier population rise time unchanged suggesting that fast relaxation is maintained upon considerable changes of the level spacing. This corroborates recent models explaining the relaxation by polaron formation in combination with quantum kinetic effects.

  8. Acceleration of microparticle

    CERN Document Server

    Shibata, H

    2002-01-01

    A microparticle (dust) ion source has been installed at the high voltage terminal of the 3.75 MV single ended Van de Graaff electrostatic accelerator and a beam line for microparticle experiments has been build at High Fluence Irradiation Facility (HIT) of Research Center for Nuclear Science and Technology, the University of Tokyo. Microparticle acceleration has been successful in obtaining expected velocities of 1-20 km/s or more for micron or submicron sized particles. Development of in situ dust detectors and analyzers on board satellites and spacecraft in the expected mass and velocity range of micrometeoroids and investigation of hypervelocity impact phenomena by using time of flight mass spectrometry, impact flash or luminescence measurement and scanning electron or laser microscope observation for metals, ceramics, polymers and semiconductors bombarded by micron-sized particles were started three years ago. (author)

  9. Macroscopic kinematics of the Hall electric field under influence of carrier magnetic moments

    International Nuclear Information System (INIS)

    Sakai, Masamichi

    2016-01-01

    The relativistic effect on electromagnetic forces yields two types of forces which depend on the velocity of the relevant particles: (i) the usual Lorentz force exerted on a moving charged particle and (ii) the apparent Lorentz force exerted on a moving magnetic moment. In sharp contrast with type (i), the type (ii) force originates due to the transverse field induced by the Hall effect (HE). This study incorporates both forces into a Drude-type equation with a fully spin-polarized condition to investigate the effects of self-consistency of the source and the resultant fields on the HE. We also examine the self-consistency of the carrier kinematics and electromagnetic dynamics by simultaneously considering the Drude type equation and Maxwell equations at low frequencies. Thus, our approach can predict both the dc and ac characteristics of the HE, demonstrating that the dc current condition solely yields the ordinary HE, while the ac current condition yields generation of both fundamental and second harmonic modes of the HE field. When the magnetostatic field is absent, the simultaneous presence of dc and ac longitudinal currents generates the ac HE that has both fundamental frequency and second harmonic.

  10. PAMAM Dendrimers as Potential Carriers of Gadolinium Complexes of Iminodiacetic Acid Derivatives for Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    Magdalena Markowicz-Piasecka

    2015-01-01

    Full Text Available This is the first study describing the utilization of PAMAM dendrimers as delivery vehicles of novel magnetic resonance imaging (MRI contrast agents. The purpose of this paper was to establish the potential of G4 PAMAM dendrimers as carriers of gadolinium complexes of iminodiacetic acid derivatives and determine imaging properties of synthesized compounds in in vivo studies. Furthermore, we examined the influence of four synthesized complexes on the process of clot formation, stabilization, and lysis and on amidolytic activity of thrombin. Biodistribution studies have shown that the compounds composed of PAMAM G4 dendrimers and gadolinium complexes of iminodiacetic acid derivatives increase signal intensity preferably in liver in range of 59–116% in MRI studies which corresponds with the greatest accumulation of gadolinium after administration of the compounds. Synthesized compounds affect kinetic parameters of the proces of clot formation, its stabilization, and lysis. However, only one synthesized compound at concentration 10-fold higher than potential plasma concentrations contributed to the increase of general parameters such as the overall potential of clot formation and lysis (↑CLAUC and total time of the process (↑T. Results of described studies provide additional insight into delivery properties of PAMAM dendrimers but simultaneously underscore the necessity for further research.

  11. Microparticle analysis system and method

    Science.gov (United States)

    Morrison, Dennis R. (Inventor)

    2007-01-01

    A device for analyzing microparticles is provided which includes a chamber with an inlet and an outlet for respectively introducing and dispensing a flowing fluid comprising microparticles, a light source for providing light through the chamber and a photometer for measuring the intensity of light transmitted through individual microparticles. The device further includes an imaging system for acquiring images of the fluid. In some cases, the device may be configured to identify and determine a quantity of the microparticles within the fluid. Consequently, a method for identifying and tracking microparticles in motion is contemplated herein. The method involves flowing a fluid comprising microparticles in laminar motion through a chamber, transmitting light through the fluid, measuring the intensities of the light transmitted through the microparticles, imaging the fluid a plurality of times and comparing at least some of the intensities of light between different images of the fluid.

  12. Duchenne muscular dystrophy carriers. Proton spin-lattice relaxation times of skeletal muscles on magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, K.; Nakano, I. (Shimoshizu National Hospital, Chiba (Japan). Dept. of Neurology); Fukuda, N.; Ikehira, H.; Tateno, Y. (National Inst. of Radiological Sciences, Chiba (Japan). Div. of Clinical Research); Aoki, Y. (National Inst. of Radiological Sciences, Chiba (Japan))

    1989-11-01

    By means of magnetic resonance imaging (MRI), the proton spin-lattice relaxation times (T1 values) of the skeletal muscles were measured in Duchenne muscular dystrophy (DMD) carriers and normal controls. The bound water fraction (BWF) was calculated from the T1 values obtained, according to the fast proton diffusion model. In the DMD carriers, T1 values of the gluteus maximus and quadriceps femoris muscles were significantly higher, and BWFs of these muscles were significantly lower than in normal control. Degenerative muscular changes accompanied by interstitial edema were presumed responsible for this abnormality. No correlation was observed between the muscle T1 and serum creatine kinase values. The present study showed that MRI could be a useful method for studying the dynamic state of water in both normal and pathological skeletal muscles. Its possible utility for DMD carrier detection was discussed briefly. (orig.).

  13. Profile analysis of microparticles

    International Nuclear Information System (INIS)

    Konarski, P.; Iwanejko, I.; Mierzejewska, A.

    2001-01-01

    Depth resolved analyses of several types of microparticles are presented. Particles for secondary ion mass spectrometry (SIMS) depth profile analysis were collected in the working environment of glass plant, steelworks and welding station using eight-stage cascade impactor with particle size range of 0.3 μm to 15 μm. Ion beam sputtering and sample rotation technique allowed to describe morphology i.e. the elemental structure of collected sub-micrometer particles. Also model particles Iriodin 221 (Merck) were depth profiled. The core-shell structure is found for all types of investigated particles. Steelworks particles consist mainly of iron and manganese cores. At the shells of these microparticles: lead, chlorine and fluorine are found. The particles collected in the glass-works consist mainly of lead-zirconium glass cores covered by carbon and copper. Stainless-steel welding particles compose of iron, manganese and chromium cores covered by a shell rich in carbon, chlorine and fluorine. Sample rotation technique applied in SIMS appears to be an effective tool for environmental microparticle morphology studies

  14. Impulsion of nanoparticles as a drug carrier for the theoretical investigation of stenosed arteries with induced magnetic effects

    Energy Technology Data Exchange (ETDEWEB)

    Nadeem, S.; Ijaz, S., E-mail: shagufta.me2011@yahoo.com

    2016-07-15

    In this paper hemodynamics of stenosis are discussed to predict effect of atherosclerosis by means of mathematical models in the presence of uniform transverse magnetic field. The analysis is carried out using silver and copper nanoparticles as a drug carrier. Exact solution for the fluid temperature, velocity, axial induced magnetic field and current density distribution are obtained under mild stenosis approximation. The results indicate that with an increase in the concentration of nanoparticle hemodynamics effects of stenosis reduces throughout the inclined composite stenosed arteries. The considered analysis also summarizes that the drug silver nanoparticles is more efficient to reduce hemodynamics of stenosis when compare to the drug copper nanoparticle. In future this model could be helpful to predict important properties in some biomedical applications. - Highlights: • The contribution of copper and silver nanoparticles as drug carrier reveals that they are important to reduce hemodynamic of stenosis. • The heat is dissipated throughout the considered inclined artery with an increase in the nanoparticle volume fraction. • The stress on the wall of inclined arteries decreases with an increase in the magnetic Reynolds number and Strommers number.

  15. Synthesis of a smart pH-responsive magnetic nanocomposite as high loading carrier of pharmaceutical agents.

    Science.gov (United States)

    Berah, Razieh; Ghorbani, Mohsen; Moghadamnia, Ali Akbar

    2017-06-01

    To create facile external controlled drug delivery system, a magnetic porous carrier based on Tin oxide nanoparticles was synthesized by an inexpensive and versatile hydrothermal strategy and used for in-vitro process. Magnetic nanocomposites were qualified by Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Vibrational Sample Magnetometer (VSM) and Transmission Electron Microscopy (TEM). Results showed that nanoparticles were synthesized successfully with good dispersion of magnetic nanoparticles in cavity, uniform particle size distribution with average size of 65nm and high magnetization of 33.75 emu/mg. Furthermore, the nano-porosity and magnetism allowed high efficiency and remote controlled drug release. In this study, anti-migraine Sumatriptan was used as drug sample and the effect of drug concentration, Fe/Sn ratio and loading time on drug absorption were investigated. The best result was checked for stability at body temperature and different body pH. The sample with drug concentration of 0.25(mg/ml), Fe/Sn=0.22 and loading time of 1.5h had the highest drug efficiency (70%). Finally, in order to simulate the in vivo process for in-vitro step, Amnion was used and drug diffusion rate was measured in different intervals and different pH values. The result illustrated that after 25h, diffusion reached 65% at pH=2 and 56% at pH=7, and then became constant. Based on the above mentioned results, the carrier has an acceptable in vitro yield and therefore could be chosen for future in vivo researches. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Review Article: Fabricated Microparticles: An Innovative Method to Minimize the Side Effects of NSAIDs in Arthritis.

    Science.gov (United States)

    Abadi, Shaivad Shabee Hulhasan; Moin, Afrasim; Veerabhadrappa, Gangadharappa Hosahalli

    2016-01-01

    Microparticles are polymeric bodies ranging 1-1000 µm that constitute a variety of forms such as microcapsules, microspheres, microcages, microshells, microrods, biosensors microparticles, radiolabeled microparticles, and so forth. This review focuses on general microparticles, mainly microcapsules and microspheres. Nonsteriodal anti-inflammatory drugs (NSAIDs) are one of the mostcommonly prescribed medications in the world. Most of the NSAIDs available have severe side effects. With increased awareness of NSAID-induced gastrointestinal (GI) side effects, safety has become a priority in treatment of arthritis and other inflammatory diseases with NSAIDs. A trend in NSAID development has been to improve therapeutic efficacy while reducing the severity of GI side effects by altering dosage through modified release to optimize drug delivery. One such approach is the use of fabricated microparticles such as microcapsules and microspheres as carriers of drugs. Microparticles provide delivery of macromolecules and micromolecules via different routes and effectively control the release profile of such drugs. Microcapsules and microspheres are compatible with most natural and synthetic polymers and can be used for several routes of administration, including parenteral, oral, nasal, intra-ocular, topical, and the like. Because of greater stability and multiple manufacturing techniques, microspheres and microcapsules are preferred as drug carriers over other colloidal drug delivery systems. Microparticles provide effective protection of the encapsulated agent against degradation by enzymatic activities, controlled and confined delivery of drugs from a few hours to months, and ingenious administration compared to alternative forms of controlled-release parenteral dosages, such as macro-sized implants. This comprehensive overview of fabricated microparticles describes microencapsulation technologies to produce microparticles for targeted therapy of arthritis and other

  17. A concept of ferroelectric microparticle propulsion thruster

    International Nuclear Information System (INIS)

    Yarmolich, D.; Vekselman, V.; Krasik, Ya. E.

    2008-01-01

    A space propulsion concept using charged ferroelectric microparticles as a propellant is suggested. The measured ferroelectric plasma source thrust, produced mainly by microparticles emission, reaches ∼9x10 -4 N. The obtained trajectories of microparticles demonstrate that the majority of the microparticles are positively charged, which permits further improvement of the thruster

  18. Application of magnetic carriers to two examples of quantitative cell analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Chen; Qian, Zhixi; Choi, Young Suk; David, Allan E. [Department of Chemical Engineering, 212 Ross Hall, Auburn University, Auburn, AL 36849 (United States); Todd, Paul, E-mail: pwtodd@hotmail.com [Techshot, Inc., 7200 Highway 150, Greenville, IN 47124 (United States); Hanley, Thomas R. [Department of Chemical Engineering, 212 Ross Hall, Auburn University, Auburn, AL 36849 (United States)

    2017-04-01

    The use of magnetophoretic mobility as a surrogate for fluorescence intensity in quantitative cell analysis was investigated. The objectives of quantitative fluorescence flow cytometry include establishing a level of labeling for the setting of parameters in fluorescence activated cell sorters (FACS) and the determination of levels of uptake of fluorescently labeled substrates by living cells. Likewise, the objectives of quantitative magnetic cytometry include establishing a level of labeling for the setting of parameters in flowing magnetic cell sorters and the determination of levels of uptake of magnetically labeled substrates by living cells. The magnetic counterpart to fluorescence intensity is magnetophoretic mobility, defined as the velocity imparted to a suspended cell per unit of magnetic ponderomotive force. A commercial velocimeter available for making this measurement was used to demonstrate both applications. Cultured Gallus lymphoma cells were immunolabeled with commercial magnetic beads and shown to have adequate magnetophoretic mobility to be separated by a novel flowing magnetic separator. Phagocytosis of starch nanoparticles having magnetic cores by cultured Chinese hamster ovary cells, a CHO line, was quantified on the basis of magnetophoretic mobility. - Highlights: • Commercial particle tracking velocimetry measures magnetophoretic mobility of labeled cells. • Magnetically labeled tumor cells were shown to have adequate mobility for capture in a specific sorter. • The kinetics of nonspecific endocytosis of magnetic nanomaterials by CHO cells was characterized. • Magnetic labeling of cells can be used like fluorescence flow cytometry for quantitative cell analysis.

  19. Aerosol-Assisted Fast Formulating Uniform Pharmaceutical Polymer Microparticles with Variable Properties toward pH-Sensitive Controlled Drug Release

    Directory of Open Access Journals (Sweden)

    Hong Lei

    2016-05-01

    Full Text Available Microencapsulation is highly attractive for oral drug delivery. Microparticles are a common form of drug carrier for this purpose. There is still a high demand on efficient methods to fabricate microparticles with uniform sizes and well-controlled particle properties. In this paper, uniform hydroxypropyl methylcellulose phthalate (HPMCP-based pharmaceutical microparticles loaded with either hydrophobic or hydrophilic model drugs have been directly formulated by using a unique aerosol technique, i.e., the microfluidic spray drying technology. A series of microparticles of controllable particle sizes, shapes, and structures are fabricated by tuning the solvent composition and drying temperature. It is found that a more volatile solvent and a higher drying temperature can result in fast evaporation rates to form microparticles of larger lateral size, more irregular shape, and denser matrix. The nature of the model drugs also plays an important role in determining particle properties. The drug release behaviors of the pharmaceutical microparticles are dependent on their structural properties and the nature of a specific drug, as well as sensitive to the pH value of the release medium. Most importantly, drugs in the microparticles obtained by using a more volatile solvent or a higher drying temperature can be well protected from degradation in harsh simulated gastric fluids due to the dense structures of the microparticles, while they can be fast-released in simulated intestinal fluids through particle dissolution. These pharmaceutical microparticles are potentially useful for site-specific (enteric delivery of orally-administered drugs.

  20. Preparation of donut-shaped starch microparticles by aqueous-alcoholic treatment.

    Science.gov (United States)

    Farrag, Yousof; Sabando, Constanza; Rodríguez-Llamazares, Saddys; Bouza, Rebeca; Rojas, Claudio; Barral, Luís

    2018-04-25

    A simple method for producing donut-shaped starch microparticles by adding ethanol to a heated aqueous slurry of corn starch is presented. The obtained microparticles were analysed by SEM, XRD and DSC. The average size of microparticles was 14.1 ± 0.3 μm with holes of an average size of 4.6 ± 0.2 μm. The crystalline arrangement of the microparticles was of a V-type single helix. The change in crystallinity from A-type of the starch granules to a more open structure, where water molecules could penetrate easier within the microparticles, substantially increased their solubility and swelling power. The microparticles exhibited a higher gelatinization temperature and a lower gelatinization enthalpy than did the starch granules. The donut-shaped microparticles were stable for more than 18 months and can be used as a carrier of an active compound or as a filler in bioplastics. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Magnetic Particles as Multifunctional Transport Carriers and Fluid Drivers in Micro Systems

    NARCIS (Netherlands)

    Derks, R.J.S.; Frijns, A.J.H.; Prins, M.W.J.; Dietzel, A.H.

    2008-01-01

    Magnetic actuation principles using superparamagnetic particles suspended in a fluid are studied in this paper. Two experimental setups for different magnetic field settings are designed and fabricated. On the basis of optical velocity measurements, the induced behavior of single and ordered chains

  2. Design and characterization of core-shell mPEG-PLGA composite microparticles for development of cell-scaffold constructs

    DEFF Research Database (Denmark)

    Wen, Yanhong; Gallego, Monica Ramos; Nielsen, Lene Feldskov

    2013-01-01

    /DS or Alg/CS/DS particles in the mPEG-PLGA microparticles were significantly dependent on the operating conditions, including the flow rate ratio (Qout/Qin) and the viscosity of the polymer solutions (Vout, Vin) between the outer and the inner feeding channels. The core-shell composite microparticles.......e. more sustainable cell growth was induced by the DS released from the core-shell composite microparticles comprising Alg/CS/DS particles. After seeding fibroblasts onto the composite microparticles, excellent cell adhesion was observed, and a successful assembly of the cell-scaffold constructs...... was induced within 7 days. Therefore, the present study demonstrates a novel strategy for fabrication of core-shell composite microparticles comprising additional particulate drug carriers in the core, which provides controlled delivery of DS and favorable cell biocompatibility; an approach to potentially...

  3. DNA tagged microparticles

    Science.gov (United States)

    Farquar, George R.; Leif, Roald N.; Wheeler, Elizabeth

    2016-03-22

    In one embodiment, a product includes a plurality of particles, each particle including: a carrier that includes a non-toxic material; and at least one DNA barcode coupled to the carrier, where the particles each have a diameter in a range from about 1 nanometer to about 100 microns.

  4. Four-dimensional (4D) tracking of high-temperature microparticles

    International Nuclear Information System (INIS)

    Wang, Zhehui; Liu, Q.; Waganaar, W.; Fontanese, J.; James, D.; Munsat, T.

    2016-01-01

    High-speed tracking of hot and molten microparticles in motion provides rich information about burning plasmas in magnetic fusion. An exploding-wire apparatus is used to produce moving high-temperature metallic microparticles and to develop four-dimensional (4D) or time-resolved 3D particle tracking techniques. The pinhole camera model and algorithms developed for computer vision are used for scene calibration and 4D reconstructions. 3D positions and velocities are then derived for different microparticles. Velocity resolution approaches 0.1 m/s by using the local constant velocity approximation.

  5. Membrane microparticles and diseases.

    Science.gov (United States)

    Wu, Z-H; Ji, C-L; Li, H; Qiu, G-X; Gao, C-J; Weng, X-S

    2013-09-01

    Membrane microparticles (MPs) are plasma membrane-derived vesicles shed by various types of activated or apoptotic cells including platelets, monocytes, endothelial cells, red blood cells, and granulocytes. MPs are being increasingly recognized as important regulators of cell-to-cell interactions. Recent evidences suggest they may play important functions not only in homeostasis but also in the pathogenesis of a number of diseases such as vascular diseases, cancer, infectious diseases and diabetes mellitus. Accordingly, inhibiting the production of MPs may serve as a novel therapeutic strategy for these diseases. Here we review recent advances on the mechanism underlying the generation of MPs and the role of MPs in vascular diseases, cancer, diabetes, inflammation, and pathogen infection.

  6. Magnetic dipole self-organization of charge carriers in high-temperature superconductors and kinetics of phase transformation

    CERN Document Server

    Voronov, A V; Shuvalov, V V

    2001-01-01

    The phenomenological model, describing the magnetic dipole self-organization of charge carriers (formation of so-called stripe-structures and energy gap in the states spectrum), is designed for interpreting the data on the nonstationary nonlinear spectroscopy of the high-temperature superconductors. It is shown that after fast heating of the superconducting sample the kinetics of the subsequent phase transition depends on the initial temperature T. The destruction of the stripe-structures at low overheating T* < T < T sub m approx = (1.4-1.5)T*, whereby T sub c and T* approx = T sub c are the temperatures of transition into the superconducting state and formation of the stripe-structures occurs slowly (the times above 10 sup - sup 9 s) in spite of practically instantaneous disappearance of the superconductivity

  7. Polylactide-based magnetic spheres as efficient carriers for anticancer drug delivery

    CSIR Research Space (South Africa)

    Mhlanga, N

    2015-09-01

    Full Text Available To improve traditional cancer therapies, we synthesized polylactide (PLA) spheres coencapsulating magnetic nanoparticles (MNPs, Fe(sub3)O(sub4)) and an anticancer drug (doxorubicin, DOX). The synthesis process involves the preparation of Fe(sub3)O...

  8. Furosemide Loaded Silica-Lipid Hybrid Microparticles: Formulation Development, in vitro and ex vivo Evaluation.

    Science.gov (United States)

    Sambaraj, Swapna; Ammula, Divya; Nagabandi, Vijaykumar

    2015-09-01

    The main objective of the current research work was to formulate and evaluate furosemide loaded silica lipid hybrid microparticles for improved oral delivery. A novel silica-lipid hybrid microparticulate system is used for enhancing the oral absorption of low solubility and low permeability of (BCS Class IV) drugs. Silica-lipid hybrid microparticles include the drug solubilising effect of dispersed lipids and stabilizing effect of hydrophilic silica particles to increase drug solubilisation, which leads to enhanced oral bioavailability. The slica lipid hybrid (SLH) microparticles were composed of poorly soluble drug (furosemide), dispersion of oil phase (Soya bean oil and miglyol) in lecithin (Phospholipoid 90H), non-ionic surfactant (Polysorbate 80) and adsorbent (Aerosol 380). Saturation solubility studies were performed in different oils and surfactants with increased concentration of drug revealed increased solubility of furosemide. In vitro dissolution studies conducted under simulated gastric medium revealed 2-4 fold increase in dissolution efficiencies for SLH microparticles compared to that of pure drug (furosemide) and marketed formulation Lasix®. Ex vivo studies showed enhanced lipid digestibility, which improved drug permeability. Solid-state characterization of SLH microparticles by X-ray powder diffraction and Fourier transform infrared spectroscopic analysis confirmed non-crystalline nature and more compatibility of furosemide in silica-lipid hybrid microparticles. It can be concluded that the role of lipids and hydrophilic silica based carrier highlighted in enhancing solubility and permeability, and hence the oral bioavailability of poorly soluble drugs.

  9. Potential roles of cell-derived microparticles in ischemic brain disease.

    Science.gov (United States)

    Horstman, Lawrence L; Jy, Wenche; Bidot, Carlos J; Nordberg, Mary L; Minagar, Alireza; Alexander, J Steven; Kelley, Roger E; Ahn, Yeon S

    2009-10-01

    The objective of this study is to review the role of cell-derived microparticles in ischemic cerebrovascular diseases. An extensive PubMed search of literature pertaining to this study was performed in April 2009 using specific keyword search terms related to cell-derived microparticles and ischemic stroke. Some references are not cited here as it is not possible to be all inclusive or due to space limitation. Cell-derived microparticles are small membranous vesicles released from the plasma membranes of platelets, leukocytes, red cells and endothelial cells in response to diverse biochemical agents or mechanical stresses. They are the main carriers of circulating tissue factor, the principal initiator of intravascular thrombosis, and are implicated in a variety of thrombotic and inflammatory disorders. This review outlines evidence suggesting that cell-derived microparticles are involved predominantly with microvascular, as opposed to macrovascular, thrombosis. More specifically, cell-derived microparticles may substantially contribute to ischemic brain disease in several settings, as well as to neuroinflammatory conditions. If further work confirms this hypothesis, novel therapeutic strategies for minimizing cell-derived microparticles-mediated ischemia are available or can be developed, as discussed.

  10. Magnetic permeability based diagnostic test for the determination of the canine C-reactive protein concentration in undiluted whole blood

    International Nuclear Information System (INIS)

    Ibraimi, Filiz; Kriz, Kirstin; Merin, Henrik; Kriz, Dario

    2009-01-01

    We describe an one-step 11-min magnetic permeability based two-site immunoassay for C-reactive protein (CRP) utilizing polyclonal anti-canine CRP antibody conjugated dextran iron oxide nanoparticles (79 nm) as superparamagnetic labels and polyclonal anti-canine CRP conjugated silica microparticles (15 to 40 μm) as carriers. An inductance based magnetic permeability reader was used to detect the target analyte, CRP, in 10 μL whole blood samples, by measuring the magnetic permeability increase of the silica microparticle sediment due to immuno complex superparamagnetic nanoparticles. Measurements on standards showed a linear response between 0 and 17.5 mg/L CRP. Measurements performed on 16 whole blood samples from mixed breeds showed good correlation with a commercially available ELISA assay.

  11. Reconfigurable engineered motile semiconductor microparticles.

    Science.gov (United States)

    Ohiri, Ugonna; Shields, C Wyatt; Han, Koohee; Tyler, Talmage; Velev, Orlin D; Jokerst, Nan

    2018-05-03

    Locally energized particles form the basis for emerging classes of active matter. The design of active particles has led to their controlled locomotion and assembly. The next generation of particles should demonstrate robust control over their active assembly, disassembly, and reconfiguration. Here we introduce a class of semiconductor microparticles that can be comprehensively designed (in size, shape, electric polarizability, and patterned coatings) using standard microfabrication tools. These custom silicon particles draw energy from external electric fields to actively propel, while interacting hydrodynamically, and sequentially assemble and disassemble on demand. We show that a number of electrokinetic effects, such as dielectrophoresis, induced charge electrophoresis, and diode propulsion, can selectively power the microparticle motions and interactions. The ability to achieve on-demand locomotion, tractable fluid flows, synchronized motility, and reversible assembly using engineered silicon microparticles may enable advanced applications that include remotely powered microsensors, artificial muscles, reconfigurable neural networks and computational systems.

  12. The appearance of microparticles in accelerator tubes

    International Nuclear Information System (INIS)

    Griffiths, G.L.; Eastham, D.A.; Kivlin, F.J.

    1978-07-01

    Microparticles have been found in submodules of accelerator tubes during the voltage conditioning process. The microparticle detector uses electrostatic induction and time-of-flight measurements to determine the charge and velocity of microparticles. Preliminary measurements with a charge sensitive limit of about 5 x 10 -15 C proves the presence of microparticles at a threshold voltage well below the onset of microdischarges or voltage breakdown. No direct evidence relating microparticles to the initiation of electrical breakdown has been found in this experiment. (author)

  13. Preparation, structural and magnetic investigation, and toxicity assays of SPIONs as carriers of nitric oxide

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Luana Caroline; Seabra, Amedea Barozzi; Haddad, Paula Silvia, E-mail: luana.unifesp@gmail.com [Universidade Federal de Sao Paulo (UNIFESP), Sao Paulo, SP (Brazil)

    2016-07-01

    Full text: The features of nanoparticles and their biocompatibility are being the subject of great interest in biomedical areas. Structural and magnetic features and the evaluation of cytotoxicity of nanoparticles (NPs) are extremely important in nanomedicine [1]. In this scenario, the present work is focused on the synthesis, characterization and cytotoxic evaluation of superparamagnetic iron oxide nanoparticles (SPIONs). The nanoparticle of magnetite (Fe{sub 3}O{sub 4}) was obtained from thermal decomposition [2] of Fe(acac){sub 3} compound. At first, we investigated the synthetic parameters, such as temperature and reaction time, in order to improve physicochemical properties of the nanoparticles. In addition, the surface of synthesized NPs was functionalized with mercaptosuccinic acid (MSA) to form thiolate nanoparticles. Free thiol groups of thiolate nanoparticles were nitrosated leading to S-nitrosothiol groups (-SNO), which are able to release the free radical nitric oxide (NO), involved in several biological processes. The structural characterization was done by FTIR and XRD techniques, showing the formation of Fe{sub 3}O{sub 4} with size of 11 nm, in solid state. Moreover, magnetization measurements showed superparamagnetic behavior. The amount of free - SH groups onto surface of NPs was found to be 2,81 ± 1.63 μmol SH per gram of NP. Dynamic light scattering revealed the hydrodynamic size of 412.10 ± 3.20 nm, polidispersitivity of 0.32 and zeta potential of -22.10. Upon nitrosation of thiolate NPs, 8.38 ± 4.71 mmol of NO per gram of NPs were obtained, revealing that NPs are able to spontaneously release therapeutic amount of NO suggesting the promising biomedical applications of these materials. References: [1] A. B. SEABRA e P. S. HADDAD 'Cytotoxicity and genotoxicity of iron oxide nanoparticles' in: Nanotoxicology, 1. ed., vol. 1, New York, Springer, p. 265-280, 2014. (author)

  14. Magnetic cross-linked enzyme aggregates (CLEAs): a novel concept towards carrier free immobilization of lignocellulolytic enzymes.

    Science.gov (United States)

    Bhattacharya, Abhishek; Pletschke, Brett I

    2014-01-01

    The enzymatic conversion of lignocellulosic biomass into biofuels has been identified as an excellent strategy to generate clean energy. However, the current process is cost-intensive as an effective immobilization approach to reuse the enzyme(s) has been a major challenge. The present study introduces the concept and application of novel magnetic cross-linked enzyme aggregates (mag-CLEAs). Both mag-CLEAs and calcium-mag-CLEAs (Ca-mag-CLEAs) exhibited a 1.35 fold higher xylanase activity compared to the free enzyme and retained more than 80.0% and 90.0% activity, respectively, after 136h of incubation at 50°C, compared to 50% activity retained by CLEAs. A 7.4 and 9.0 fold higher sugar release from lime-pretreated and NH4OH pre-treated sugar bagasse, respectively, was achieved with Ca-mag-CLEAs compared to the free enzymes. The present study promotes the successful application of mag-CLEAs and Ca-mag-CLEAs as carrier free immobilized enzymes for the effective hydrolysis of lignocellulolytic biomass and associated biofuel feedstocks. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Free Rhodium (II) citrate and rhodium (II) citrate magnetic carriers as potential strategies for breast cancer therapy

    Science.gov (United States)

    2011-01-01

    Background Rhodium (II) citrate (Rh2(H2cit)4) has significant antitumor, cytotoxic, and cytostatic activity on Ehrlich ascite tumor. Although toxic to normal cells, its lower toxicity when compared to carboxylate analogues of rhodium (II) indicates Rh2(H2cit)4 as a promising agent for chemotherapy. Nevertheless, few studies have been performed to explore this potential. Superparamagnetic particles of iron oxide (SPIOs) represent an attractive platform as carriers in drug delivery systems (DDS) because they can present greater specificity to tumor cells than normal cells. Thus, the association between Rh2(H2cit)4 and SPIOs can represent a strategy to enhance the former's therapeutic action. In this work, we report the cytotoxicity of free rhodium (II) citrate (Rh2(H2cit)4) and rhodium (II) citrate-loaded maghemite nanoparticles or magnetoliposomes, used as drug delivery systems, on both normal and carcinoma breast cell cultures. Results Treatment with free Rh2(H2cit)4 induced cytotoxicity that was dependent on dose, time, and cell line. The IC50 values showed that this effect was more intense on breast normal cells (MCF-10A) than on breast carcinoma cells (MCF-7 and 4T1). However, the treatment with 50 μM Rh2(H2cit)4-loaded maghemite nanoparticles (Magh-Rh2(H2cit)4) and Rh2(H2cit)4-loaded magnetoliposomes (Lip-Magh-Rh2(H2cit)4) induced a higher cytotoxicity on MCF-7 and 4T1 than on MCF-10A (p rhodium (II) citrate-loaded maghemite nanoparticles and magnetoliposomes induced more specific cytotoxicity on breast carcinoma cells than on breast normal cells, which is the opposite of the results observed with free Rh2(H2cit)4 treatment. Thus, magnetic nanoparticles represent an attractive platform as carriers in Rh2(H2cit)4 delivery systems, since they can act preferentially in tumor cells. Therefore, these nanopaticulate systems may be explored as a potential tool for chemotherapy drug development. PMID:21443799

  16. Circulating Microparticles in Patients with Benign and Malignant Ovarian Tumors

    NARCIS (Netherlands)

    Rank, A.; Liebhardt, S.; Zwirner, J.; Burges, A.; Nieuwland, R.; Toth, B.

    2012-01-01

    Background: Microparticles are known to be increased in various malignancies. In this prospective study, microparticle levels were evaluated in patients with benign and malignant ovarian lesions. Patients and Methods: Microparticles from platelets/megakaryocytes, activated platelets and endothelial

  17. Bio-threat microparticle simulants

    Science.gov (United States)

    Farquar, George Roy; Leif, Roald N

    2012-10-23

    A bio-threat simulant that includes a carrier and DNA encapsulated in the carrier. Also a method of making a simulant including the steps of providing a carrier and encapsulating DNA in the carrier to produce the bio-threat simulant.

  18. Bio-threat microparticle simulants

    Energy Technology Data Exchange (ETDEWEB)

    Farquar, George Roy; Leif, Roald

    2014-09-16

    A bio-threat simulant that includes a carrier and DNA encapsulated in the carrier. Also a method of making a simulant including the steps of providing a carrier and encapsulating DNA in the carrier to produce the bio-threat simulant.

  19. Microparticles as Potential Biomarkers of Cardiovascular Disease

    International Nuclear Information System (INIS)

    França, Carolina Nunes; Izar, Maria Cristina de Oliveira; Amaral, Jônatas Bussador do; Tegani, Daniela Melo; Fonseca, Francisco Antonio Helfenstein

    2015-01-01

    Primary prevention of cardiovascular disease is a choice of great relevance because of its impact on health. Some biomarkers, such as microparticles derived from different cell populations, have been considered useful in the assessment of cardiovascular disease. Microparticles are released by the membrane structures of different cell types upon activation or apoptosis, and are present in the plasma of healthy individuals (in levels considered physiological) and in patients with different pathologies. Many studies have suggested an association between microparticles and different pathological conditions, mainly the relationship with the development of cardiovascular diseases. Moreover, the effects of different lipid-lowering therapies have been described in regard to measurement of microparticles. The studies are still controversial regarding the levels of microparticles that can be considered pathological. In addition, the methodologies used still vary, suggesting the need for standardization of the different protocols applied, aiming at using microparticles as biomarkers in clinical practice

  20. Microparticles as Potential Biomarkers of Cardiovascular Disease

    Energy Technology Data Exchange (ETDEWEB)

    França, Carolina Nunes, E-mail: carolufscar24@gmail.com [Universidade Federal de São Paulo - UNIFESP - UNISA, SP, São Paulo (Brazil); Universidade de Santo Amaro - UNISA, SP, São Paulo (Brazil); Izar, Maria Cristina de Oliveira; Amaral, Jônatas Bussador do; Tegani, Daniela Melo; Fonseca, Francisco Antonio Helfenstein [Universidade Federal de São Paulo - UNIFESP - UNISA, SP, São Paulo (Brazil)

    2015-02-15

    Primary prevention of cardiovascular disease is a choice of great relevance because of its impact on health. Some biomarkers, such as microparticles derived from different cell populations, have been considered useful in the assessment of cardiovascular disease. Microparticles are released by the membrane structures of different cell types upon activation or apoptosis, and are present in the plasma of healthy individuals (in levels considered physiological) and in patients with different pathologies. Many studies have suggested an association between microparticles and different pathological conditions, mainly the relationship with the development of cardiovascular diseases. Moreover, the effects of different lipid-lowering therapies have been described in regard to measurement of microparticles. The studies are still controversial regarding the levels of microparticles that can be considered pathological. In addition, the methodologies used still vary, suggesting the need for standardization of the different protocols applied, aiming at using microparticles as biomarkers in clinical practice.

  1. Proton magnetic resonance spectroscopy of a boron neutron capture therapy 10B-carrier, L-p-boronophenylalanine-fructose complex

    Energy Technology Data Exchange (ETDEWEB)

    Timonen, M.

    2010-07-01

    Boron neutron capture therapy (BNCT) is a radiotherapy that has mainly been used to treat malignant brain tumours, melanomas, and head and neck cancer. In BNCT, the patient receives an intravenous infusion of a 10B-carrier, which accumulates in the tumour area. The tumour is irradiated with epithermal or thermal neutrons, which result in a boron neutron capture reaction that generates heavy particles to damage tumour cells. In Finland, boronophenylalanine fructose (BPA-F) is used as the 10B-carrier. Currently, the drifting of boron from blood to tumour as well as the spatial and temporal accumulation of boron in the brain, are not precisely known. Proton magnetic resonance spectroscopy (1H MRS) could be used for selective BPA-F detection and quantification as aromatic protons of BPA resonate in the spectrum region, which is clear of brain metabolite signals. This study, which included both phantom and in vivo studies, examined the validity of 1H MRS as a tool for BPA detection. In the phantom study, BPA quantification was studied at 1.5 and 3.0 T with single voxel 1H MRS, and at 1.5 T with magnetic resonance imaging (MRSI). The detection limit of BPA was determined in phantom conditions at 1.5 T and 3.0 T using single voxel 1H MRS, and at 1.5 T using MRSI. In phantom conditions, BPA quantification accuracy of +- 5% and +- 15% were achieved with single voxel MRS using external or internal (internal water signal) concentration references, respectively. For MRSI, a quantification accuracy of <5% was obtained using an internal concentration reference (creatine). The detection limits of BPA in phantom conditions for the PRESS sequence were 0.7 (3.0 T) and 1.4 mM (1.5 T) mM with 20 x 20 single voxel MRS, and 1.0 mM with acquisition-weighted MRSI, respectively. In the in vivo study, an MRSI or single voxel MRS or both was performed for ten patients (patients 1-10) on the day of BNCT. Three patients had glioblastoma multiforme (GBM), and five patients had a recurrent or

  2. Smart swelling biopolymer microparticles by a microfluidic approach: synthesis, in situ encapsulation and controlled release.

    Science.gov (United States)

    Fang, Aiping; Cathala, Bernard

    2011-01-01

    This paper reports a microfluidic synthesis of biopolymer microparticles aiming at smart swelling. Monodisperse aqueous emulsion droplets comprising biopolymer and its cross-linking agent were formed in mineral oil and solidified in the winding microfluidic channels by in situ chaotic mixing, which resulted in internal chemical gelation for hydrogels. The achievement of pectin microparticles from in situ mixing pectin with its cross-linking agent, calcium ions, successfully demonstrates the reliability of this microfluidic synthesis approach. In order to achieve hydrogels with smart swelling, the following parameters and their impacts on the swelling behaviour, stability and morphology of microparticles were investigated: (1) the type of biopolymers (alginate or mixture of alginate and carboxymethylcellulose, A-CMC); (2) rapid mixing; (3) concentration and type of cross-linking agent. Superabsorbent microparticles were obtained from A-CMC mixture by using ferric chloride as an additional external cross-linking agent. The in situ encapsulation of a model protein, bovine serum albumin (BSA), was also carried out. As a potential protein drug-delivery system, the BSA release behaviours of the biopolymer particles were studied in simulated gastric and intestinal fluids. Compared with alginate and A-CMC microparticles cross-linked with calcium ions, A-CMC microparticles cross-linked with both calcium and ferric ions demonstrate a significantly delayed release. The controllable release profile, the facile encapsulation as well as their biocompatibility, biodegradability, mucoadhesiveness render this microfluidic approach promising in achieving biopolymer microparticles as protein drug carrier for site-specific release. Copyright © 2010 Elsevier B.V. All rights reserved.

  3. Functional magnetic resonance imaging (fMRI of attention processes in presumed obligate carriers of schizophrenia: preliminary findings

    Directory of Open Access Journals (Sweden)

    Morris Robin G

    2008-10-01

    Full Text Available Abstract Background Presumed obligate carriers (POCs are the first-degree relatives of people with schizophrenia who, although do not exhibit the disorder, are in direct lineage of it. Thus, this subpopulation of first-degree relatives could provide very important information with regard to the investigation of endophenotypes for schizophrenia that could clarify the often contradictory findings in schizophrenia high-risk populations. To date, despite the extant literature on schizophrenia endophenotypes, we are only aware of one other study that examined the neural mechanisms that underlie cognitive abnormalities in this group. The aim of this study was to investigate whether a more homogeneous group of relatives, such as POCs, have neural abnormalities that may be related to schizophrenia. Methods We used functional magnetic resonance imaging (fMRI to collect blood oxygenated level dependent (BOLD response data in six POCs and eight unrelated healthy controls while performing under conditions of sustained, selective and divided attention. Results The POCs indicated alterations in a widely distributed network of regions involved in attention processes, such as the prefrontal and temporal (including the parahippocampal gyrus cortices, in addition to the anterior cingulate gyrus. More specifically, a general reduction in BOLD response was found in these areas compared to the healthy participants during attention processes. Conclusion These preliminary findings of decreased activity in POCs indicate that this more homogeneous population of unaffected relatives share similar neural abnormalities with people with schizophrenia, suggesting that reduced BOLD activity in the attention network may be an intermediate marker for schizophrenia.

  4. Spray-dried Eudragit® L100 microparticles containing ferulic acid: Formulation, in vitro cytoprotection and in vivo anti-platelet effect

    Energy Technology Data Exchange (ETDEWEB)

    Nadal, Jessica Mendes; Gomes, Mona Lisa Simionatto [Postgraduate Program in Pharmaceutical Sciences, Department of Pharmacy, Federal University of Paraná (Brazil); Borsato, Débora Maria [Postgraduate Program in Pharmaceutical Sciences, Department of Pharmaceutical Sciences, State University of Ponta Grossa (Brazil); Almeida, Martinha Antunes [Postgraduate Program in Chemistry, Department of Chemistry, Federal University of Paraná (Brazil); Barboza, Fernanda Malaquias [Postgraduate Program in Pharmaceutical Sciences, Department of Pharmaceutical Sciences, State University of Ponta Grossa (Brazil); Zawadzki, Sônia Faria [Postgraduate Program in Chemistry, Department of Chemistry, Federal University of Paraná (Brazil); Kanunfre, Carla Cristine [Postgraduate Program in Biomedical Science, Department of General Biology, State University of Ponta Grossa (Brazil); Farago, Paulo Vitor, E-mail: pvfarago@gmail.com [Postgraduate Program in Pharmaceutical Sciences, Department of Pharmaceutical Sciences, State University of Ponta Grossa (Brazil); Zanin, Sandra Maria Warumby [Postgraduate Program in Pharmaceutical Sciences, Department of Pharmacy, Federal University of Paraná (Brazil)

    2016-07-01

    This paper aimed to obtain new spray-dried microparticles containing ferulic acid (FA) prepared by using a methacrylic polymer (Eudragit® L100). Microparticles were intended for oral use in order to provide a controlled release, and improved in vitro and in vivo biological effects. FA-loaded Eudragit® L100 microparticles were obtained by spray-drying. Physicochemical properties, in vitro cell-based effects, and in vivo platelet aggregation were investigated. FA-loaded Eudragit® L100 microparticles were successfully prepared by spray-drying. Formulations showed suitable encapsulation efficiency, i.e. close to 100%. Microparticles were of spherical and almost-spherical shape with a smooth surface and a mean diameter between 2 and 3 μm. Fourier-transformed infrared spectra demonstrated no chemical bond between FA and polymer. X-ray diffraction and differential scanning calorimetry analyses indicated that microencapsulation led to drug amorphization. FA-loaded microparticles showed a slower dissolution rate than pure drug. The chosen formulation demonstrated higher in vitro cytoprotection, anti-inflammatory and immunomodulatory potential and also improved in vivo anti-platelet effect. These results support an experimental basis for the use of FA spray-dried microparticles as a feasible oral drug delivery carrier for the controlled release of FA and improved cytoprotective and anti-platelet effects. - Highlights: • Ferulic acid-loaded Eudragit® L100 microparticles with high drug-loading were obtained. • Spray-dried Eudragit® L100 microparticles containing ferulic acid showed improved in vitro cytoprotective effect. • Ferulic acid spray-dried microparticles had potential as in vitro anti-inflammatory and immunomodulatory. • In vivo studies demonstrated an enhanced antiplatelet effect for ferulic acid-loaded Eudragit® L100 microparticles.

  5. Spray-dried Eudragit® L100 microparticles containing ferulic acid: Formulation, in vitro cytoprotection and in vivo anti-platelet effect

    International Nuclear Information System (INIS)

    Nadal, Jessica Mendes; Gomes, Mona Lisa Simionatto; Borsato, Débora Maria; Almeida, Martinha Antunes; Barboza, Fernanda Malaquias; Zawadzki, Sônia Faria; Kanunfre, Carla Cristine; Farago, Paulo Vitor; Zanin, Sandra Maria Warumby

    2016-01-01

    This paper aimed to obtain new spray-dried microparticles containing ferulic acid (FA) prepared by using a methacrylic polymer (Eudragit® L100). Microparticles were intended for oral use in order to provide a controlled release, and improved in vitro and in vivo biological effects. FA-loaded Eudragit® L100 microparticles were obtained by spray-drying. Physicochemical properties, in vitro cell-based effects, and in vivo platelet aggregation were investigated. FA-loaded Eudragit® L100 microparticles were successfully prepared by spray-drying. Formulations showed suitable encapsulation efficiency, i.e. close to 100%. Microparticles were of spherical and almost-spherical shape with a smooth surface and a mean diameter between 2 and 3 μm. Fourier-transformed infrared spectra demonstrated no chemical bond between FA and polymer. X-ray diffraction and differential scanning calorimetry analyses indicated that microencapsulation led to drug amorphization. FA-loaded microparticles showed a slower dissolution rate than pure drug. The chosen formulation demonstrated higher in vitro cytoprotection, anti-inflammatory and immunomodulatory potential and also improved in vivo anti-platelet effect. These results support an experimental basis for the use of FA spray-dried microparticles as a feasible oral drug delivery carrier for the controlled release of FA and improved cytoprotective and anti-platelet effects. - Highlights: • Ferulic acid-loaded Eudragit® L100 microparticles with high drug-loading were obtained. • Spray-dried Eudragit® L100 microparticles containing ferulic acid showed improved in vitro cytoprotective effect. • Ferulic acid spray-dried microparticles had potential as in vitro anti-inflammatory and immunomodulatory. • In vivo studies demonstrated an enhanced antiplatelet effect for ferulic acid-loaded Eudragit® L100 microparticles.

  6. Use of the spray chilling method to deliver hydrophobic components: physical characterization of microparticles

    Directory of Open Access Journals (Sweden)

    Izabela Dutra Alvim

    2013-02-01

    Full Text Available Food industry has been developing products to meet the demands of increasing number of consumers who are concerned with their health and who seek food products that satisfy their needs. Therefore, the development of processed foods that contain functional components has become important for this industry. Microencapsulation can be used to reduce the effects of processing on functional components and preserve their bioactivity. The present study investigated the production of lipid microparticles containing phytosterols by spray chilling. The matrices comprised mixtures of stearic acid and hydrogenated vegetable fat, and the ratio of the matrix components to phytosterols was defined by an experimental design using the mean diameters of the microparticles as the response variable. The melting point of the matrices ranged from 44.5 and 53.4 ºC. The process yield was melting point dependent; the particles that exhibited lower melting point had greater losses than those with higher melting point. The microparticles' mean diameters ranged from 13.8 and 32.2 µm and were influenced by the amount of phytosterols and stearic acid. The microparticles exhibited spherical shape and typical polydispersity of atomized products. From a technological and practical (handling, yield, and agglomeration points of view, lipid microparticles with higher melting point proved promising as phytosterol carriers.

  7. Polyamide Microparticles Containing Vitamin C by Interfacial Polymerization: An Approach by Design of Experimentation

    Directory of Open Access Journals (Sweden)

    Lionel Ripoll

    2016-11-01

    Full Text Available Vitamin C is widely use in cosmetics and pharmaceutics products for its active properties. However ascorbic acid shows unfavourable chemical instability such as oxidation leading to formulation problems. Therefore, carriers, such as micro- and nanoparticles, have been widely investigated as delivery systems for vitamin C to improve its beneficial effects in skin treatment. However, none of the previous studies have been able to produce microparticles with a high encapsulation entrapment of vitamin C. The aim of the present study is to use an experimental design to optimize the synthesis of polyamide microparticles for the delivery of ascorbic acid. The effect of four formulation parameters on microparticles properties (size and morphology, encapsulation efficiency and yield, release kinetics were investigated using a surface response design. Finally, we were able to obtain stable microparticles containing more than 65% of vitamin C. This result confirms the effectiveness of using design of experiments for the optimisation of microparticle formulation and supports the proposal of using them as candidate for the delivery of vitamin C in skin treatment.

  8. Hydrophilic porous magnetic poly(GMA-MBAA-NVP) composite microspheres containing oxirane groups: An efficient carrier for immobilizing penicillin G acylase

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Ping; Su, Weiguang, E-mail: weiguangsu@nxu.edu.cn; Gu, Yaohua; Liu, Haifeng; Wang, Julan

    2015-03-15

    Magnetic hydrophilic polymeric microspheres containing oxirane groups were prepared by inverse suspension polymerization of glycidyl methacrylate (GMA), N, N′-methylene bisacrylamide (MBAA) and N-vinyl pyrrolidone (NVP) in the existence of formamide, which were denoted as magnetic poly(GMA-MBAA-NVP) microspheres. The magnetic poly(GMA-MBAA-NVP) microspheres were characterized by scanning electron microscopy (SEM), FT-IR spectroscopy, X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and so on. The results showed that poly(GMA-MBAA-NVP) microspheres possessed well spherical shape, narrow size distribution, abundant porous structure, reactive oxirane groups and superparamagnetic properties. Formamide used in the present work served as a modifier, a dispersant and a porogen to form final porous polymer microspheres. The penicillin G acylase (PGA) was covalently immobilized onto the magnetic microspheres through the reaction between the amino groups of enzyme and the oxirane groups on the microspheres for producing 6-aminopenicillanic acid (6-APA). The effects of GMA/NVP ratio and crosslink density on the activity of immobilized PGA were investigated. The highest apparent activity, enzyme loading and coupling yield of immobilized PGA were 821 IU/g, 65.3 mg/g and 42.3% respectively when the mass ratio of GMA/NVP was 1:1 and crosslink density was 60%. Compared with the free PGA, immobilized PGA showed a wider range of pH value and reaction temperature. The relative activity and reaction rate of immobilized PGA remained almost constant after 20 recycles. The magnetic poly(GMA-MBAA-NVP) microspheres would be very promising carriers for immobilizing enzymes in industrial application. - Highlights: • The magnetic poly(GMA-MBAA-NVP) microspheres were successfully synthesized. • Formamide served as a modifier, a dispersant and a porogen to form microspheres. • The magnetic microspheres were highly efficient carriers for immobilizing PGA. • Immobilized PGA

  9. Pharmaceutical microparticle engineering with electrospraying

    DEFF Research Database (Denmark)

    Bohr, Adam; Wan, Feng; Kristensen, Jakob

    2015-01-01

    Microparticles of Celecoxib, dispersed in a matrix of poly(lactic-co-glycolic acid) (PLGA), were prepared by electrospraying using different solvent mixtures to investigate the influence upon particle formation and the resulting particle characteristics. Mixtures consisting of a good solvent, ace...... demonstrated by the increasingly higher drug release rates. The results demonstrate the importance of solvent composition in particle preparation and indicate potential for exploiting this dependence to improve pharmaceutical particle design and performance....

  10. Regional brain metabolite abnormalities in inherited prion disease and asymptomatic gene carriers demonstrated in vivo by quantitative proton magnetic resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Waldman, A.D.; Cordery, R.J.; Godbolt, A.; Rossor, M.N. [University College London, Dementia Research Group, Department of Neurodegenerative Disease, Institute of Neurology, London (United Kingdom); Imperial College of Science, Technology and Medicine, Division of Neuroscience and Psychological Medicine, Faculty of Medicine, London (United Kingdom); MacManus, D.G. [University College London, NMR Research Unit, Department of Clinical Neurology, Institute of Neurology, London (United Kingdom); Collinge, J. [University College London, MRC Prion Unit, Department of Neurodegenerative Disease, Institute of Neurology, London (United Kingdom)

    2006-06-15

    Inherited prion diseases are caused by mutations in the gene which codes for prion protein (PrP), leading to proliferation of abnormal PrP isomers in the brain and neurodegeneration; they include Gerstmann-Straeussler-Scheinker disease (GSS), fatal familial insomnia (FFI) and familial Creutzfeldt-Jakob disease (fCJD). We studied two patients with symptomatic inherited prion disease (P102L) and two pre-symptomatic P102L gene carriers using quantitative magnetic resonance spectroscopy (MRS). Short echo time spectra were acquired from the thalamus, caudate region and frontal white matter, metabolite levels and ratios were measured and z-scores calculated for individual patients relative to age-matched normal controls. MRS data were compared with structural magnetic resonance imaging. One fCJD case had generalised atrophy and showed increased levels of myo-inositol (MI) in the thalamus (z=3.7). The other had decreased levels of N-acetylaspartate (z=4) and diffuse signal abnormality in the frontal white matter. Both asymptomatic gene carriers had normal imaging, but increased frontal white matter MI (z=4.3, 4.1), and one also had increased MI in the caudate (z=5.3). Isolated MI abnormalities in asymptomatic gene carriers are a novel finding and may reflect early glial proliferation, prior to significant neuronal damage. MRS provides potential non-invasive surrogate markers of early disease and progression in inherited prion disease. (orig.)

  11. Regional brain metabolite abnormalities in inherited prion disease and asymptomatic gene carriers demonstrated in vivo by quantitative proton magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Waldman, A.D.; Cordery, R.J.; Godbolt, A.; Rossor, M.N.; MacManus, D.G.; Collinge, J.

    2006-01-01

    Inherited prion diseases are caused by mutations in the gene which codes for prion protein (PrP), leading to proliferation of abnormal PrP isomers in the brain and neurodegeneration; they include Gerstmann-Straeussler-Scheinker disease (GSS), fatal familial insomnia (FFI) and familial Creutzfeldt-Jakob disease (fCJD). We studied two patients with symptomatic inherited prion disease (P102L) and two pre-symptomatic P102L gene carriers using quantitative magnetic resonance spectroscopy (MRS). Short echo time spectra were acquired from the thalamus, caudate region and frontal white matter, metabolite levels and ratios were measured and z-scores calculated for individual patients relative to age-matched normal controls. MRS data were compared with structural magnetic resonance imaging. One fCJD case had generalised atrophy and showed increased levels of myo-inositol (MI) in the thalamus (z=3.7). The other had decreased levels of N-acetylaspartate (z=4) and diffuse signal abnormality in the frontal white matter. Both asymptomatic gene carriers had normal imaging, but increased frontal white matter MI (z=4.3, 4.1), and one also had increased MI in the caudate (z=5.3). Isolated MI abnormalities in asymptomatic gene carriers are a novel finding and may reflect early glial proliferation, prior to significant neuronal damage. MRS provides potential non-invasive surrogate markers of early disease and progression in inherited prion disease. (orig.)

  12. Preparation of Starch/Gelatin Blend Microparticles by a Water-in-Oil Emulsion Method for Controlled Release Drug Delivery.

    Science.gov (United States)

    Phromsopha, Theeraphol; Baimark, Yodthong

    2014-01-01

    Information on the preparation and properties of starch/gelatin blend microparticles with and without crosslinking for drug delivery is presented. The blend microparticles were prepared by the water-in-oil emulsion solvent diffusion method. Glutaraldehyde and methylene blue were used as the crosslinker and the water-soluble drug model, respectively. The blend microparticles were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and UV-Vis spectroscopy. The functional groups of the starch and gelatin blend matrices were determined from the FTIR spectra. Blend microparticles with a nearly spherical shape and internal porous structure were observed from SEM images. The average particle size of the gelatin microparticles depended on the crosslinker ratio but not on the starch/gelatin blend ratio. The in vitro drug release content significantly decreased as the crosslinker ratio increased and the starch blend ratio decreased. The results demonstrated that the starch/gelatin blend microparticles should be a useful controlled release delivery carrier for water-soluble drugs.

  13. Laser ablation of microparticles for nanostructure generation

    International Nuclear Information System (INIS)

    Waraich, Palneet Singh; Tan, Bo; Venkatakrishnan, Krishnan

    2011-01-01

    The process of laser ablation of microparticles has been shown to generate nanoparticles from microparticles; but the generation of nanoparticle networks from microparticles has never been reported before. We report a unique approach for the generation of nanoparticle networks through ablation of microparticles. Using this approach, two samples containing microparticles of lead oxide (Pb 3 O 4 ) and nickel oxide (NiO), respectively, were ablated under ambient conditions using a femtosecond laser operating in the MHz repetition rate regime. Nanoparticle networks with particle diameter ranging from 60 to 90 nm were obtained by ablation of microparticles without use of any specialized equipment, catalysts or external stimulants. The formation of finer nanoparticle networks has been explained by considering the low pressure region created by the shockwave, causing rapid condensation of microparticles into finer nanoparticles. A comparison between the nanostructures generated by ablating microparticle and those by ablating bulk substrate was carried out; and a considerable reduction in size and narrowed size distribution was observed. Our nanostructure fabrication technique will be a unique process for nanoparticle network generation from a vast array of materials.

  14. Improved intestinal absorption of a poorly water-soluble oral drug using mannitol microparticles containing a nanosolid drug dispersion.

    Science.gov (United States)

    Nishino, Yukiko; Kubota, Aya; Kanazawa, Takanori; Takashima, Yuuki; Ozeki, Tetsuya; Okada, Hiroaki

    2012-11-01

    A nozzle for a spray dryer that can prepare microparticles of water-soluble carriers containing various nanoparticles in a single step was previously developed in our laboratory. To enhance the solubility and intestinal absorption of poorly water-soluble drugs, we used probucol (PBL) as a poorly water-soluble drug, mannitol (MAN) as a water-soluble carrier for the microparticles, and EUDRAGIT (EUD) as a polymer vehicle for the solid dispersion. PBL-EUD-acetone-methanol and aqueous MAN solutions were simultaneously supplied through different liquid passages of the spray nozzle and dried together. PBL-EUD solid dispersion was nanoprecipitated in the MAN solution using an antisolvent mechanism and rapidly dried by surrounding it with MAN. PBL in the dispersion vehicle was amorphous and had higher physical stability according to powder X-ray diffraction and differential scanning calorimetry analysis. The bioavailability of PBL in PBL-EUD S-100-MAN microparticles after oral administration in rats was markedly higher (14- and 6.2-fold, respectively) than that of the original PBL powder and PBL-MAN microparticles. These results demonstrate that the composite microparticles containing a nanosized solid dispersion of a poorly water-soluble drug prepared using the spray nozzle developed by us should be useful to increase the solubility and bioavailability of drugs after oral administration. Copyright © 2012 Wiley Periodicals, Inc.

  15. Physical and arsenic adsorption properties of maghemite and magnetite sub-microparticles

    Science.gov (United States)

    Mejia-Santillan, M. E.; Pariona, N.; Bravo-C., J.; Herrera-Trejo, M.; Montejo-Alvaro, F.; Zarate, A.; Perry, D. L.; Mtz-Enriquez, A. I.

    2018-04-01

    The topotactic transformation from magnetite to maghemite sub-microparticles was demonstrated by a variety of techniques that include X-ray diffraction, Raman spectroscopy, electron microscopy, Mössbauer spectroscopy, magnetic measurements, and vis-NIR diffuse reflectance. The physical, chemical, and morphological properties of the particles were correlated with their adsorptive properties in water with respect to arsenic (V). The adsorptive properties of the iron oxide are increased by changing the crystal phases involved, specifically, the transformation of magnetite to maghemite. Maghemite sub-microparticles are capable of efficiently decreasing the arsenic content in water from 100 ppb to below the World Health Organization (WHO) guideline of 10 ppb.

  16. Possible role of rf melted microparticles on the operation of high-gradient accelerating structures

    Directory of Open Access Journals (Sweden)

    G. S. Nusinovich

    2009-10-01

    Full Text Available High-gradient accelerating structures should operate reliably for a long time. Therefore studies of various processes which may lead to disruption of such an operation are so important. In the present paper, the dissipation of rf electromagnetic energy in metallic microparticles is analyzed accounting for the temperature dependence of the skin depth. Such particles may appear in structures, for example, due to mechanical fracture of irises in strong rf electric fields. It is shown that such microparticles with dimensions on the order of the skin depth, being immersed in the region of strong rf magnetic field, can absorb enough energy in long-pulse operation to be melted. Then, the melted clumps can impinge on the surface of a structure and create nonuniformities leading to field enhancement and corresponding emission of dark current. Results are given for several geometries and materials of microparticles.

  17. Taste-masking assessment of orally disintegrating tablets and lyophilisates with cetirizine dihydrochloride microparticles

    Directory of Open Access Journals (Sweden)

    Aleksandra Amelian

    2017-12-01

    Full Text Available Orally disintegrating tablets and oral lyophilisates are novel attractive dosage forms that disintegrate or dissolve in the buccal cavity within seconds without necessity of drinking. The major limitation in designing of these dosage forms is unpleasant taste of the drug substance. Cetirizine dihydrochloride is a H1-antihistamine substance indicated for the treatment of allergy. It is characterized by extremely bitter taste, therefore in order to deliver cetirizine dihydrochloride using orodispersible formulations, effective taste-masking is required. The aim of this study was to investigate whether microparticles containing cetirizine dihydrochloride could be successfully used to formulate orally disintegrating tablets by direct compression method and oral lyophilisates by freeze-drying process. Taste masking of cetirizine dihydrochloride was achieved by the spray-drying technique using Eudragit® E PO as the drug agent carrier. Based on the preliminary studies, optimal compositions of microparticles, tablets and lyophilisates were chosen. Obtained dosage forms were characterized for drug content, disintegration time and mechanical properties. In order to determine whether the microparticles subjected to direct compression and freeze-drying process effectively mask the bitter taste of cetirizine dihydrochloride, the in vivo and in vitro evaluation was performed. The results showed that designed formulates with microparticles containing cetirizine dihydrochloride were characterized by appropriate mechanical properties, uniformity of weight and thickness, short disintegration time, and the uniform content of the drug substance. Taste-masking assessment performed by three independent methods (e-tongue evaluation, human test panel and the in vitro drug release revealed that microparticles with Eudragit® E PO are effective taste – masking carriers of cetirizine dihydrochloride and might be used to formulate orally disintegrating tablets and oral

  18. Laser plasma jet driven microparticles for DNA/drug delivery.

    Directory of Open Access Journals (Sweden)

    Viren Menezes

    Full Text Available This paper describes a microparticle delivery device that generates a plasma jet through laser ablation of a thin metal foil and uses the jet to accomplish particle delivery into soft living targets for transferring biological agents. Pure gold microparticles of 1 µm size were coated with a plasmid DNA, pIG121Hm, and were deposited as a thin layer on one surface of an aluminum foil. The laser (Nd:YAG, 1064 nm wavelength ablation of the foil generated a plasma jet that carried the DNA coated particles into the living onion cells. The particles could effectively penetrate the target cells and disseminate the DNA, effecting the transfection of the cells. Generation of the plasma jet on laser ablation of the foil and its role as a carrier of microparticles was visualized using a high-speed video camera, Shimadzu HPV-1, at a frame rate of 500 kfps (2 µs interframe interval in a shadowgraph optical set-up. The particle speed could be measured from the visualized images, which was about 770 m/s initially, increased to a magnitude of 1320 m/s, and after a quasi-steady state over a distance of 10 mm with an average magnitude of 1100 m/s, started declining, which typically is the trend of a high-speed, pulsed, compressible jet. Aluminum launch pad (for the particles was used in the present study to make the procedure cost-effective, whereas the guided, biocompatible launch pads made of gold, silver or titanium can be used in the device during the actual clinical operations. The particle delivery device has a potential to have a miniature form and can be an effective, hand-held drug/DNA delivery device for biological applications.

  19. Cavitational micro-particles: plasma formation mechanisms

    International Nuclear Information System (INIS)

    Bica, Ioan

    2005-01-01

    Cavitational micro-particles are a class to which the micro-spheres, the micro-tubes and the octopus-shaped micro-particles belong. The cavitational micro-particles (micro-spheres, micro-tubes and octopus-shaped micro-particles) at an environmental pressure. The micro-spheres, the micro-tubes and the ligaments of the octopus-shaped micro-particles are produced in the argon plasma and are formed of vapors with low values of the molar concentration in comparison with the molar density of the gas and vapor mixture, the first one on the unstable and the last two on the stable movement of the vapors. The ligaments of the octopus-shaped micro-particles are open at the top for well-chosen values of the sub-cooling of the vapor and gas cylinders. The nitrogen in the air favors the formation of pores in the wall of the micro-spheres. In this paper we present the cavitational micro-particles, their production in the plasma and some mechanisms for their formation in the plasma. (author)

  20. Obtain and characterization of chitosan / propranolol microparticles by spray drying; Obtencao e caracterizacao de microparticulas de quitosana / propranolol por spray drying

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Ednaldo G. do; Silva Junior, Arnobio A. da, E-mail: ednaldogn@yahoo.com.br [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Santos, Katia S.C.R. dos [Universidade Federal do Amazonas (UFAM), Manaus, AM (brazil)

    2015-07-01

    The study investigated the application of chitosan microparticles as carriers into hard gelatin capsule containing propranolol, evaluating the variability of the molecular weight and the chitosan particles by spray drying. The formulations were characterized by average weight, dosing unit dose uniformity and dissolution profile according to the pharmacopoeia. While the microparticles were characterized by Fourier transformed infrared spectroscopy, scanning electron microscopy and X-ray diffraction. The results showed that chitosan microparticles obtained without the drug and then physically mixed with propranolol promoted a modified release 85% of the drug after 5 hours. While, chitosan microparticles sprayed with propranolol released only 55% at 5 hours is presented both as a modified release system. Samples of dried chitosan showed up amorphous and homogeneous and spherical morphology. (author)

  1. Composite microparticles of halloysite clay nanotubes bound by calcium carbonate.

    Science.gov (United States)

    Jin, Yi; Yendluri, Raghuvara; Chen, Bin; Wang, Jingbo; Lvov, Yuri

    2016-03-15

    Natural halloysite clay nanotubes with 15 nm inner and 75 nm outer diameters have been used as vehicles for sustained release of drugs in composite hollow microparticles "glued" with CaCO3. We used a layer-by layer assembly accomplished alginate binding with Ca(2+) followed by CO2 bubbling to prepare the composite microspheres of CaCO3 and polyelectrolytes (PE) modified halloysite nanotubes (HNTs-PE2/CaCO3) with the diameter of about 5-10 μm. These microparticles have empty spherical structure and abundant pore distributions with maxima at 2.5, 3.9, 6.0 and 13.3 nm, and higher surface area of 82.3 m(2) g(-1) as characterized by SEM and BET test. We loaded drugs in these micro-nano carriers of tight piles of halloysite nanotube with end clogged with CaCO3. The sustained release of Nifedipine drug from HNTs-PE2/CaCO3 composite microspheres was slower than for pristine halloysite nanotubes. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Relaxation of microparticles exposed to hydrodynamic forces in microfluidic conduits.

    Science.gov (United States)

    Janča, Josef; Halabalová, Věra; Polášek, Vladimír; Vašina, Martin; Menshikova, Anastasia Yu

    2011-02-01

    The behavior of microparticles exposed to gravitational and lift forces and to the velocity gradient in flow velocity profile formed in microfluidic conduits is studied from the viewpoint of the transient period (the relaxation) between the moment at which a particle starts to be transported by the hydrodynamic flow and the time at which it reaches an equilibrium position, characterized by a balance of all active forces. The theoretical model allowing the calculation of the relaxation time is proposed. The numerical calculus based on the proposed model is compared with the experimental data obtained under different experimental conditions, namely, for different lengths of microfluidic channels, different average linear velocities of the carrier liquid, and different sizes and densities of the particles used in the study. The results are important for the optimization of microfluidic separation units such as microthermal field-flow fractionation channels in which the separation or manipulation of the microparticles of various origin, synthetic, natural, biological, etc., is performed under similar experimental conditions but by applying an additional thermodynamic force.

  3. A novel bio-safe phase separation process for preparing open-pore biodegradable polycaprolactone microparticles.

    Science.gov (United States)

    Salerno, Aurelio; Domingo, Concepción

    2014-09-01

    Open-pore biodegradable microparticles are object of considerable interest for biomedical applications, particularly as cell and drug delivery carriers in tissue engineering and health care treatments. Furthermore, the engineering of microparticles with well definite size distribution and pore architecture by bio-safe fabrication routes is crucial to avoid the use of toxic compounds potentially harmful to cells and biological tissues. To achieve this important issue, in the present study a straightforward and bio-safe approach for fabricating porous biodegradable microparticles with controlled morphological and structural features down to the nanometer scale is developed. In particular, ethyl lactate is used as a non-toxic solvent for polycaprolactone particles fabrication via a thermal induced phase separation technique. The used approach allows achieving open-pore particles with mean particle size in the 150-250 μm range and a 3.5-7.9 m(2)/g specific surface area. Finally, the combination of thermal induced phase separation and porogen leaching techniques is employed for the first time to obtain multi-scaled porous microparticles with large external and internal pore sizes and potential improved characteristics for cell culture and tissue engineering. Samples were characterized to assess their thermal properties, morphology and crystalline structure features and textural properties. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Hybrid calcium carbonate/polymer microparticles containing silver nanoparticles as antibacterial agents

    Science.gov (United States)

    Długosz, Maciej; Bulwan, Maria; Kania, Gabriela; Nowakowska, Maria; Zapotoczny, Szczepan

    2012-12-01

    We report here on synthesis and characterization of novel hybrid material consisting of silver nanoparticles (nAgs) embedded in calcium carbonate microparticles (μ-CaCO3) serving as carriers for sustained release. nAgs are commonly used as antimicrobial agents in many commercial products (textiles, cosmetics, and drugs). Although they are considered to be safe, their interactions with human organisms are still not fully understood; therefore it is important to apply them with caution and limit their presence in the environment. The synthesis of the new material was based on the co-precipitation of CaCO3 and nAg in the presence of poly(sodium 4-styrenesulfonate). Such designed system enables sustained release of nAg to the environment. This hybrid colloidal material (nAg/μ-CaCO3) was characterized by microscopic and spectroscopic methods. The release of nAg from μ-CaCO3 microparticles was followed in water at various pH values. Microbiological tests confirmed the effectiveness of these microparticles as an antibacterial agent. Importantly, the material can be stored as a dry powder and subsequently re-suspended in water without the risk of losing its antimicrobial activity. nAg/μ-CaCO3 was applied here to insure bacteriostatic properties of down feathers that may significantly prolong their lifetime in typical applications. Such microparticles may be also used as, e.g., components of coatings and paints protecting various surfaces against microorganism colonization.

  5. Hybrid calcium carbonate/polymer microparticles containing silver nanoparticles as antibacterial agents

    International Nuclear Information System (INIS)

    Długosz, Maciej; Bulwan, Maria; Kania, Gabriela; Nowakowska, Maria; Zapotoczny, Szczepan

    2012-01-01

    We report here on synthesis and characterization of novel hybrid material consisting of silver nanoparticles (nAgs) embedded in calcium carbonate microparticles (μ-CaCO 3 ) serving as carriers for sustained release. nAgs are commonly used as antimicrobial agents in many commercial products (textiles, cosmetics, and drugs). Although they are considered to be safe, their interactions with human organisms are still not fully understood; therefore it is important to apply them with caution and limit their presence in the environment. The synthesis of the new material was based on the co-precipitation of CaCO 3 and nAg in the presence of poly(sodium 4-styrenesulfonate). Such designed system enables sustained release of nAg to the environment. This hybrid colloidal material (nAg/μ-CaCO 3 ) was characterized by microscopic and spectroscopic methods. The release of nAg from μ-CaCO 3 microparticles was followed in water at various pH values. Microbiological tests confirmed the effectiveness of these microparticles as an antibacterial agent. Importantly, the material can be stored as a dry powder and subsequently re-suspended in water without the risk of losing its antimicrobial activity. nAg/μ-CaCO 3 was applied here to insure bacteriostatic properties of down feathers that may significantly prolong their lifetime in typical applications. Such microparticles may be also used as, e.g., components of coatings and paints protecting various surfaces against microorganism colonization.

  6. Chained Iron Microparticles for Directionally Controlled Actuation of Soft Robots.

    Science.gov (United States)

    Schmauch, Marissa M; Mishra, Sumeet R; Evans, Benjamin A; Velev, Orlin D; Tracy, Joseph B

    2017-04-05

    Magnetic field-directed self-assembly of magnetic particles in chains is useful for developing directionally responsive materials for applications in soft robotics. Using materials with greater complexity allows advanced functions, while still using simple device architectures. Elastomer films containing chained magnetic microparticles were prepared through solvent casting and formed into magnetically actuated lifters, accordions, valves, and pumps. Chaining both enhances actuation and imparts a directional response. Cantilevers used as lifters were able to lift up to 50 times the mass of the polymer film. We introduce the "specific torque", the torque per field per mass of magnetic particles, as a figure of merit for assessing and comparing the performance of lifters and related devices. Devices in this work generated specific torques of 68 Nm/kgT, which is significantly higher than in previously reported actuators. Applying magnetic fields to folded accordion structures caused extension and compression, depending on the accordion's orientation. In peristaltic pumps comprised of composite tubes containing embedded chains, magnetic fields caused a section of the tube to pinch closed where the field was applied. These results will facilitate both the further development of soft robots based on chained magnetic particles and efforts to engineer materials with higher specific torque.

  7. PLGA/DPPC/trimethylchitosan spray-dried microparticles for the nasal delivery of ropinirole hydrochloride: in vitro, ex vivo and cytocompatibility assessment

    Energy Technology Data Exchange (ETDEWEB)

    Karavasili, Christina [Laboratory of Pharmaceutical Technology, Department of Pharmacy, Aristotle University of Thessaloniki, 54124 (Greece); Bouropoulos, Nikolaos [Department of Materials Science, University of Patras, 26504 Rio, Patras (Greece); Foundation for Research and Technology, Hellas-Institute of Chemical Engineering and High Temperature, P.O. Box 1414, 26504 Patras (Greece); Sygellou, Lamprini [Foundation for Research and Technology, Hellas-Institute of Chemical Engineering and High Temperature, P.O. Box 1414, 26504 Patras (Greece); Amanatiadou, Elsa P.; Vizirianakis, Ioannis S. [Laboratory of Pharmacology, Department of Pharmaceutical Sciences, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); Fatouros, Dimitrios G., E-mail: dfatouro@pharm.auth.gr [Laboratory of Pharmaceutical Technology, Department of Pharmacy, Aristotle University of Thessaloniki, 54124 (Greece)

    2016-02-01

    In the present study we investigated polymer-lipid microparticles loaded with ropinirole hydrochloride (RH) for nasal delivery. RH microparticles were further evaluated by means of scanning electron microscopy (SEM), ζ-potential measurements, Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD). In vitro release studies were performed in simulated nasal electrolyte solution (SNES) pH 5.5 at 35 °C. Ex vivo permeation studies were conducted across sheep nasal mucosa. Cytocompatibility was tested in cultured human airway epithelial cells (Calu-3). SEM studies revealed spheroid microparticles in the range of 2.09 μm to 2.41 μm. The presence of trimethylchitosan (TMC) induced a slight shift towards less negative ζ-potential values. Surface chemistry (XPS) revealed the presence of dipalmitoylphospatidylcholine (DPPC) and poly(lactic-co-glycolic acid) (PLGA) onto microparticles' surface, further corroborating the FT-IR and XRD findings. In vitro release studies showed that the microparticle composition can partly modulate the release of RH. Ex vivo studies demonstrated a 2.35-folded enhancement of RH permeation when RH was co-formulated with TMC of low molecular weight, compared to the control. All formulations tested were found to be non-toxic to cells. The results suggest that polymer-lipid microparticles may be a promising carrier for the nasal delivery of RH. - Highlights: • Development of microparticles comprising PLGA/DPPC/TMC for nasal drug delivery. • Physicochemical characterization showed that DPPC dominated microparticles' surface. • Microparticles enhanced permeation of ropinirole across sheep nasal epithelium. • The cytotoxicity assay with Calu-3 cells demonstrated satisfactory cell viability.

  8. PLGA/DPPC/trimethylchitosan spray-dried microparticles for the nasal delivery of ropinirole hydrochloride: in vitro, ex vivo and cytocompatibility assessment

    International Nuclear Information System (INIS)

    Karavasili, Christina; Bouropoulos, Nikolaos; Sygellou, Lamprini; Amanatiadou, Elsa P.; Vizirianakis, Ioannis S.; Fatouros, Dimitrios G.

    2016-01-01

    In the present study we investigated polymer-lipid microparticles loaded with ropinirole hydrochloride (RH) for nasal delivery. RH microparticles were further evaluated by means of scanning electron microscopy (SEM), ζ-potential measurements, Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD). In vitro release studies were performed in simulated nasal electrolyte solution (SNES) pH 5.5 at 35 °C. Ex vivo permeation studies were conducted across sheep nasal mucosa. Cytocompatibility was tested in cultured human airway epithelial cells (Calu-3). SEM studies revealed spheroid microparticles in the range of 2.09 μm to 2.41 μm. The presence of trimethylchitosan (TMC) induced a slight shift towards less negative ζ-potential values. Surface chemistry (XPS) revealed the presence of dipalmitoylphospatidylcholine (DPPC) and poly(lactic-co-glycolic acid) (PLGA) onto microparticles' surface, further corroborating the FT-IR and XRD findings. In vitro release studies showed that the microparticle composition can partly modulate the release of RH. Ex vivo studies demonstrated a 2.35-folded enhancement of RH permeation when RH was co-formulated with TMC of low molecular weight, compared to the control. All formulations tested were found to be non-toxic to cells. The results suggest that polymer-lipid microparticles may be a promising carrier for the nasal delivery of RH. - Highlights: • Development of microparticles comprising PLGA/DPPC/TMC for nasal drug delivery. • Physicochemical characterization showed that DPPC dominated microparticles' surface. • Microparticles enhanced permeation of ropinirole across sheep nasal epithelium. • The cytotoxicity assay with Calu-3 cells demonstrated satisfactory cell viability.

  9. Trojan Microparticles for Drug Delivery

    Directory of Open Access Journals (Sweden)

    Thierry F. Vandamme

    2012-01-01

    Full Text Available During the last decade, the US Food and Drug Administration (FDA have regulated a wide range of products, (foods, cosmetics, drugs, devices, veterinary, and tobacco which may utilize micro and nanotechnology or contain nanomaterials. Nanotechnology allows scientists to create, explore, and manipulate materials in nano-regime. Such materials have chemical, physical, and biological properties that are quite different from their bulk counterparts. For pharmaceutical applications and in order to improve their administration (oral, pulmonary and dermal, the nanocarriers can be spread into microparticles. These supramolecular associations can also modulate the kinetic releases of drugs entrapped in the nanoparticles. Different strategies to produce these hybrid particles and to optimize the release kinetics of encapsulated drugs are discussed in this review.

  10. Preparation and chemical stability of iron-nitride-coated iron microparticles

    International Nuclear Information System (INIS)

    Luo Xin; Liu Shixiong

    2007-01-01

    Iron-nitride-coated iron microparticles were prepared by nitridation of the surface of iron microparticles with ammonia gas at a temperature of 510 deg. C. The phases, composition, morphology, magnetic properties, and chemical stability of the particles were studied. The phases were α-Fe, ε-Fe 3 N, and γ-Fe 4 N. The composition varied from the core to the surface, with 99.8 wt% Fe in the core, and 93.8 wt% Fe and 6 wt% N in the iron-nitride coating. The thickness of the iron-nitride coating was about 0.28 μm. The chemical stability of the microparticles was greatly improved, especially the corrosion resistance in corrosive aqueous media. The saturation magnetization and the coercive force were 17.1x10 3 and 68 kA/m, respectively. It can be concluded that iron-nitride-coated iron microparticles will be very useful in many fields, such as water-based magnetorheological fluids and polishing fluids

  11. Hydrophilic porous magnetic poly(GMA-MBAA-NVP) composite microspheres containing oxirane groups: An efficient carrier for immobilizing penicillin G acylase

    Science.gov (United States)

    Xue, Ping; Su, Weiguang; Gu, Yaohua; Liu, Haifeng; Wang, Julan

    2015-03-01

    Magnetic hydrophilic polymeric microspheres containing oxirane groups were prepared by inverse suspension polymerization of glycidyl methacrylate (GMA), N, N‧-methylene bisacrylamide (MBAA) and N-vinyl pyrrolidone (NVP) in the existence of formamide, which were denoted as magnetic poly(GMA-MBAA-NVP) microspheres. The magnetic poly(GMA-MBAA-NVP) microspheres were characterized by scanning electron microscopy (SEM), FT-IR spectroscopy, X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and so on. The results showed that poly(GMA-MBAA-NVP) microspheres possessed well spherical shape, narrow size distribution, abundant porous structure, reactive oxirane groups and superparamagnetic properties. Formamide used in the present work served as a modifier, a dispersant and a porogen to form final porous polymer microspheres. The penicillin G acylase (PGA) was covalently immobilized onto the magnetic microspheres through the reaction between the amino groups of enzyme and the oxirane groups on the microspheres for producing 6-aminopenicillanic acid (6-APA). The effects of GMA/NVP ratio and crosslink density on the activity of immobilized PGA were investigated. The highest apparent activity, enzyme loading and coupling yield of immobilized PGA were 821 IU/g, 65.3 mg/g and 42.3% respectively when the mass ratio of GMA/NVP was 1:1 and crosslink density was 60%. Compared with the free PGA, immobilized PGA showed a wider range of pH value and reaction temperature. The relative activity and reaction rate of immobilized PGA remained almost constant after 20 recycles. The magnetic poly(GMA-MBAA-NVP) microspheres would be very promising carriers for immobilizing enzymes in industrial application.

  12. Development of Alginate/Chitosan Microparticles for Dust Mite ...

    African Journals Online (AJOL)

    Erah

    surface of chitosan microparticles [4]. .... The reverse-phase high performance liquid .... The surface charge of alginate ... negative charge was as a result of the alginate on the microparticle surface. ... electrostatic interaction of the positively-.

  13. Microparticles and exosomes: impact on normal and complicated pregnancy

    NARCIS (Netherlands)

    Toth, Bettina; Lok, Christianne A. R.; Böing, Anita; Diamant, Michaela; van der Post, Joris A. M.; Friese, Klaus; Nieuwland, Rienk

    2007-01-01

    Eukaryotic cells release vesicles into their environment by membrane shedding (ectosomes or microparticles) and secretion (exosomes). Microparticles and exosomes occur commonly in vitro and in vivo. The occurrence, composition and function(s) of these vesicles change during disease (progression).

  14. Biomass-based magnetic fluorescent nanoparticles: One-step scalable synthesis, application as drug carriers and mechanism study.

    Science.gov (United States)

    Li, Lei; Wang, Feijun; Shao, Ziqiang

    2018-03-15

    A biomass-based magnetic fluorescent nanoparticle (MFNPs) was successively in situ synthesized via a one-step high-gravity approach, which constructed by a magnetic core of Fe 3 O 4 nanoparticles, the fluorescent marker of carbon dots (CDs), and shells of chitosan (CS). The obtained MFNPs had a 10 nm average diameter and narrow particle size distribution, low cytotoxicity, superior fluorescent emission and superparamagnetic properties. The encapsulating and release 5-fluorouracil experiments confirmed that the introduction of CS/CDs effectively improved the drug loading capacity. Mechanism and kinetic studies proved that: (i) the monolayer adsorption was the main sorption mode under the studied conditions; (ii) the whole adsorption process was controlled by intra-liquid diffusion mass transfer and governed by chemisorption; and (iii) the release process was controlled by Fickian diffusion. These results demonstrated this method to one-step continuously produce MFNPs and the construction of non-toxic nanostructure possessed great superiority in currently Nano-delivery systems, which would show high application value in targeted drug delivery, magnetic fluid hyperthermia treatment, magnetic resonance imaging (MRI), in vitro testing and relative research. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. The formulation, characterization and in vivo evaluation of a magnetic carrier for brain delivery of NIR dye

    Energy Technology Data Exchange (ETDEWEB)

    Raut, S L; Kirthivasan, B; Bommana, M M; Squillante, E; Sadoqi, M, E-mail: squillae@stjohns.edu, E-mail: sadoqim@stjohns.edu [College of Pharmacy and Allied Health Professions, St John' s University, Queens, NY 11439 (United States)

    2010-10-01

    This work reports the targeting of the near infrared (NIR) dye indocyanine green (ICG) to the brain using composite nanoparticles. Thermal decomposition of iron pentacarbonyl was used to synthesize monodisperse oleic acid coated magnetic nanoparticles (OAMNP). Synthesized OAMNP and ICG were encapsulated in a poly (lactide-co-glycolide) matrix using an emulsion evaporation method. Different batches containing OAMNP:PLGA ratios (1:4, 1:2 and 3:4) were prepared with ICG (group B-1, 2, 3) and without ICG (group A-1, 2, 3) loading. All the formulations were characterized in terms of morphology, particle size, zeta potential, magnetic content, ICG encapsulation efficiency and the spectral properties of ICG. The optimized formulation showed an encapsulation efficiency of 56 {+-} 4.6% for ICG and 57 {+-} 1.37% for OAMNP. The biodistribution and brain targeting study involved three groups of six animals, each with 0.4 mg kg{sup -1} equivalent of ICG, given as neat ICG solution, composite nanoparticles without the aid of a magnetic field, and composite nanoparticles under the influence of a magnetic field (8000 G) to groups 1, 2 and 3 respectively. The tissue analysis and microscopy images revealed a significantly higher brain concentration of ICG (p < 0.05) for group 3 than the two control groups. These results are encouraging for the brain delivery of hydrophilic dyes/drugs using this method for biomedical applications.

  16. Application of magnetic carriers for whole DNA isolation and detection of probiotic Lactobacillus gasseri K7 strain in complex samples

    Czech Academy of Sciences Publication Activity Database

    Trachtová, Š.; Obermajer, T.; Španová, A.; Bogovič, M. B.; Rogelj, I.; Horák, Daniel; Rittich, B.

    -, č. 4 (2009), A27-A28 ISSN 1727-7906. [International Congress of the SOMED /32./ - Probiotics 2009. 29.10.2009-30.10.2009, St. Petersburg] R&D Projects: GA MŠk 2B06053 Institutional research plan: CEZ:AV0Z40500505 Keywords : magnetic * DNA * microsphers Subject RIV: EE - Microbiology, Virology

  17. Magnetic particles as liquid carriers in the microfluidic lab-in-tube approach to detect phase change.

    Science.gov (United States)

    Blumenschein, Nicholas A; Han, Daewoo; Caggioni, Marco; Steckl, Andrew J

    2014-06-11

    Magnetic beads (MBs) with ∼1.9 μm average diameter were used to transport specific microliter-scale volumes of liquids between adjacent reservoirs within a closed tube under the influence of a magnetic field. The tube's inner surface is coated with a hydrophobic layer, enabling the formation of a surface tension valve by inserting an air gap between reservoirs. This transfer process was implemented by keeping the MBs stationary with a fixed external magnet while the liquid reservoirs were translated by a computer-controlled syringe pump system. The magnet induces the aggregation of MBs in a loosely packed cluster (void volume ∼90-95%) against the tube's inner wall. The liquid trapped in the MB cluster is transported across the air gap between reservoirs. Fluorescence intensity from a dye placed in one reservoir is used to measure the volume of liquid transferred between reservoirs. The carry-over liquid volume is controlled by the mass of the MBs within the device. The typical volume of liquid carried by the MB cluster is ∼2 to 3 μL/mg of beads, allowing the use of small samples. This technique can be used to study the effect of small compositional variation on the properties of fluid mixtures. The feasibility of this "lab-in-tube" approach for binary phase diagram determination in a water-surfactant (C12E5) system was demonstrated.

  18. Use of microparticles as internal targets for nuclear physics with storage rings

    Energy Technology Data Exchange (ETDEWEB)

    Berdoz, A; Heinz, A; Meyer, H O; Pancella, P; Rinckel, T; Ross, A; Sperisen, F; Young, D

    1989-04-01

    We report on the development of ultrathin (10/sup 14/ to 10/sup 16/ at/cm/sup 2/) internal targets for storage rings using microparticles. A ''dust beam'' is created by a gas-particle mixture flowing through a capillary into vacuum. In a laminar flow, the viscous drag accelerates the particles in the direction of the gas flow, while the Bernoulli force concentrates them near the axis of the tube. At the exist of the tube the gas diffuses, but the particles, due to their inertia, continue with small divergence. This property will allow us to differentially pump the carrier gas along the dust beam axis before the microparticles enter the high vacuum of the storage ring. (orig.).

  19. Use of microparticles as internal targets for nuclear physics with storage rings

    International Nuclear Information System (INIS)

    Berdoz, A.; Heinz, A.; Meyer, H.O.; Pancella, P.; Rinckel, T.; Ross, A.; Sperisen, F.; Young, D.

    1989-01-01

    We report on the development of ultrathin (10 14 to 10 16 at/cm 2 ) internal targets for storage rings using microparticles. A ''dust beam'' is created by a gas-particle mixture flowing through a capillary into vacuum. In a laminar flow, the viscous drag accelerates the particles in the direction of the gas flow, while the Bernoulli force concentrates them near the axis of the tube. At the exist of the tube the gas diffuses, but the particles, due to their inertia, continue with small divergence. This property will allow us to differentially pump the carrier gas along the dust beam axis before the microparticles enter the high vacuum of the storage ring. (orig.)

  20. Cell behavior on microparticles with different surface morphology

    International Nuclear Information System (INIS)

    Huang Sha; Fu Xiaobing

    2010-01-01

    Microparticles can serve as substrates for cell amplification and deliver the cell aggregation to the site of the defect for tissue regeneration. To develop favorable microparticles for cell delivery application, we fabricated and evaluated three types of microparticles that differ in surface properties. The microparticles with varied surface morphology (smooth, pitted and multicavity) were created from chemically crosslinked gelatin particles that underwent various drying treatments. Three types of microparticles were characterized and assessed in terms of the cell behavior of human keratinocytes and fibroblasts seeded on them. The cells could attach, spread and proliferate on all types of microparticles but spread and populated more slowly on the microparticles with smooth surfaces than on those with pitted or multicavity surfaces. Microparticles with a multicavity surface demonstrated the highest cell attachment and growth rate. Furthermore, cells tested on microparticles with a multicavity surface exhibited better morphology and induced the earlier formation of extracellular-based cell-microparticle aggregation than those on microparticles with other surface morphology (smooth and pitted). Thus, microparticles with a multicavity surface show promise for attachment and proliferation of cells in tissue engineering.

  1. Influence of microparticle size on cavitation noise during ultrasonic vibration

    Directory of Open Access Journals (Sweden)

    H. Ge

    2015-09-01

    Full Text Available The cavitation noise in the ultrasonic vibration system was found to be influenced by the size of microparticles added in water. The SiO2 microparticles with the diameter smaller than 100 μm reduced the cavitation noise, and the reason was attributed to the constrained oscillation of the cavitation bubbles, which were stabilized by the microparticles.

  2. Nanocomposite of CeO.sub.2./sub. and high-coercivity magnetic carrier with large specific surface area

    Czech Academy of Sciences Publication Activity Database

    Řezníčková Mantlíková, Alice; Plocek, Jiří; Pacáková, Barbara; Kubíčková, Simona; Vik, Ondřej; Nižňanský, D.; Šlouf, Miroslav; Vejpravová, Jana

    2016-01-01

    Roč. 2016, Nov (2016), s. 1-13, č. článku 7091241. ISSN 1687-4110 R&D Projects: GA ČR(CZ) GA15-01953S; GA MŠk(CZ) LO1507 Institutional support: RVO:68378271 ; RVO:61388980 ; RVO:61389013 Keywords : cobalt ferrite * cerium oxide * nanoparticles * catalysis Subject RIV: BM - Solid Matter Physics ; Magnetism; CD - Macromolecular Chemistry (UMCH-V); CA - Inorganic Chemistry (UACH-T) Impact factor: 1.871, year: 2016

  3. Circulating microparticles: square the circle

    Science.gov (United States)

    2013-01-01

    Background The present review summarizes current knowledge about microparticles (MPs) and provides a systematic overview of last 20 years of research on circulating MPs, with particular focus on their clinical relevance. Results MPs are a heterogeneous population of cell-derived vesicles, with sizes ranging between 50 and 1000 nm. MPs are capable of transferring peptides, proteins, lipid components, microRNA, mRNA, and DNA from one cell to another without direct cell-to-cell contact. Growing evidence suggests that MPs present in peripheral blood and body fluids contribute to the development and progression of cancer, and are of pathophysiological relevance for autoimmune, inflammatory, infectious, cardiovascular, hematological, and other diseases. MPs have large diagnostic potential as biomarkers; however, due to current technological limitations in purification of MPs and an absence of standardized methods of MP detection, challenges remain in validating the potential of MPs as a non-invasive and early diagnostic platform. Conclusions Improvements in the effective deciphering of MP molecular signatures will be critical not only for diagnostics, but also for the evaluation of treatment regimens and predicting disease outcomes. PMID:23607880

  4. Fabrication and manipulation of polymeric magnetic particles with magnetorheological fluid

    International Nuclear Information System (INIS)

    Rodríguez-López, Jaime; Shum, Ho Cheung; Elvira, Luis; Montero de Espinosa, Francisco; Weitz, David A.

    2013-01-01

    Polymeric magnetic microparticles have been created using a microfluidic device via ultraviolet (UV) polymerization of double emulsions, resulting in cores of magnetorheological (MR) fluids surrounded by polymeric shells. We demonstrate that the resultant particles can be manipulated magnetically to achieve triggered rupture of the capsules. This illustrates the great potential of our capsules for triggered release of active ingredients encapsulated in the polymeric magnetic microparticles. - Highlights: ► Polymeric microparticles encapsulating MR fluids have been fabricated. ► A double-emulsion-templated approach using microfluidic techniques has been used. ► The monodisperse microparticles obtained are easily manipulated under magnetic field. ► These microparticles have great potential for encapsulation-and-release applications.

  5. Agglomeration of microparticles in complex plasmas

    International Nuclear Information System (INIS)

    Du, Cheng-Ran; Thomas, Hubertus M.; Ivlev, Alexei V.; Konopka, Uwe; Morfill, Gregor E.

    2010-01-01

    Agglomeration of highly charged microparticles was observed and studied in complex plasma experiments carried out in a capacitively coupled rf discharge. The agglomeration was caused by strong waves triggered in a particle cloud by decreasing neutral gas pressure. Using a high-speed camera during this unstable regime, it was possible to resolve the motion of individual microparticles and to show that the relative velocities of some particles were sufficiently high to overcome the mutual Coulomb repulsion and hence to result in agglomeration. After stabilizing the cloud again through the increase of the pressure, we were able to observe the aggregates directly with a long-distance microscope. We show that the agglomeration rate deduced from our experiments is in good agreement with theoretical estimates. In addition, we briefly discuss the mechanisms that can provide binding of highly charged microparticles in a plasma.

  6. Field Effect Microparticle Generation for Cell Microencapsulation.

    Science.gov (United States)

    Hsu, Brend Ray-Sea; Fu, Shin-Huei

    2017-01-01

    The diameter and sphericity of alginate-poly-L-lysine-alginate microcapsules, determined by the size and the shape of calcium alginate microspheres, affect their in vivo durability and biocompatibility and the results of transplantation. The commonly used air-jet spray method generates microspheres with a wider variation in diameter, larger sphere morphology, and evenly distributed encapsulated cells. In order to overcome these drawbacks, we designed a field effect microparticle generator to create a stable electric field to prepare microparticles with a smaller diameter and more uniform morphology. Using this electric field microparticle generator the encapsulated cells will be located at the periphery of the microspheres, and thus the supply of oxygen and nutrients for the encapsulated cells will be improved compared with the centrally located encapsulated cells in the air-jet spray method.

  7. Disposable Amperometric Immunosensor for the Determination of Human P53 Protein in Cell Lysates Using Magnetic Micro-Carriers

    Directory of Open Access Journals (Sweden)

    María Pedrero

    2016-11-01

    Full Text Available An amperometric magnetoimmunosensor for the determination of human p53 protein is described in this work using a sandwich configuration involving the covalent immobilization of a specific capture antibody onto activated carboxylic-modified magnetic beads (HOOC-MBs and incubation of the modified MBs with a mixture of the target protein and horseradish peroxidase-labeled antibody (HRP-anti-p53. The resulting modified MBs are captured by a magnet placed under the surface of a disposable carbon screen-printed electrode (SPCE and the amperometric responses are measured at −0.20 V (vs. an Ag pseudo-reference electrode, upon addition of hydroquinone (HQ as a redox mediator and H2O2 as the enzyme substrate. The magnetoimmunosensing platform was successfully applied for the detection of p53 protein in different cell lysates without any matrix effect after a simple sample dilution. The results correlated accurately with those provided by a commercial ELISA kit, thus confirming the immunosensor as an attractive alternative for rapid and simple determination of this protein using portable and affordable instrumentation.

  8. Amine-modified magnetic iron oxide nanoparticle as a promising carrier for application in bio self-healing concrete.

    Science.gov (United States)

    Seifan, Mostafa; Ebrahiminezhad, Alireza; Ghasemi, Younes; Samani, Ali Khajeh; Berenjian, Aydin

    2018-01-01

    Self-healing mechanisms are a promising solution to address the concrete cracking issue. Among the investigated self-healing strategies, the biotechnological approach is distinguished itself by inducing the most compatible material with concrete composition. In this method, the potent bacteria and nutrients are incorporated into the concrete matrix. Once cracking occurs, the bacteria will be activated, and the induced CaCO 3 crystals will seal the concrete cracks. However, the effectiveness of a bio self-healing concrete strictly depends on the viability of bacteria. Therefore, it is required to protect the bacteria from the resulted shear forces caused by mixing and drying shrinkage of concrete. Due to the positive effects on mechanical properties and the high compatibility of metallic nanoparticles with concrete composition, for the first time, we propose 3-aminopropyltriethoxy silane-coated iron oxide nanoparticles (APTES-coated IONs) as a biocompatible carrier for Bacillus species. This study was aimed to investigate the effect of APTES-coated IONs on the bacterial viability and CaCO 3 yield for future application in the concrete structures. The APTES-coated IONs were successfully synthesized and characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results show that the presence of 100 μg/mL APTES-coated IONs could increase the bacterial viability. It was also found that the CaCO 3 -specific yield was significantly affected in the presence of APTES-coated IONs. The highest CaCO 3 -specific yield was achieved when the cells were decorated with 50 μg/mL of APTES-coated IONs. This study provides new insights for the application of APTES-coated IONs in designing bio self-healing strategies.

  9. Circulating Microparticles Alter Formation, Structure, and Properties of Fibrin Clots.

    Science.gov (United States)

    Zubairova, Laily D; Nabiullina, Roza M; Nagaswami, Chandrasekaran; Zuev, Yuriy F; Mustafin, Ilshat G; Litvinov, Rustem I; Weisel, John W

    2015-12-04

    Despite the importance of circulating microparticles in haemostasis and thrombosis, there is limited evidence for potential causative effects of naturally produced cell-derived microparticles on fibrin clot formation and its properties. We studied the significance of blood microparticles for fibrin formation, structure, and susceptibility to fibrinolysis by removing them from platelet-free plasma using filtration. Clots made in platelet-free and microparticle-depleted plasma samples from the same healthy donors were analyzed in parallel. Microparticles accelerate fibrin polymerisation and support formation of more compact clots that resist internal and external fibrinolysis. These variations correlate with faster thrombin generation, suggesting thrombin-mediated kinetic effects of microparticles on fibrin formation, structure, and properties. In addition, clots formed in the presence of microparticles, unlike clots from the microparticle-depleted plasma, contain 0.1-0.5-μm size granular and CD61-positive material on fibres, suggesting that platelet-derived microparticles attach to fibrin. Therefore, the blood of healthy individuals contains functional microparticles at the levels that have a procoagulant potential. They affect the structure and stability of fibrin clots indirectly through acceleration of thrombin generation and through direct physical incorporation into the fibrin network. Both mechanisms underlie a potential role of microparticles in haemostasis and thrombosis as modulators of fibrin formation, structure, and resistance to fibrinolysis.

  10. Magnetic field dependence of conductivity and effective mass of carriers in a model of Mott-Hubbard material

    Directory of Open Access Journals (Sweden)

    L.Didukh

    2005-01-01

    Full Text Available The effect of external magnetic field h on a static conductivity of Mott-Hubbard material which is described by the model with correlated hopping of electrons has been investigated. By means of canonical transformation, the effective Hamiltonian is obtained which takes into account strong intra-site Coulomb repulsion and correlated hopping. Using a variant of generalized Hartree-Fock approximation the single-electron Green function and quasiparticle energy spectrum of the model have been calculated. The static conductivity σ has been calculated as a function of h, electron concentration n and temperature T. The correlated hopping is shown to cause the electron-hole asymmetry of transport properties of narrow band materials.

  11. Strategy for the hemocompatibility testing of microparticles.

    Science.gov (United States)

    Braune, S; Basu, S; Kratz, K; Johansson, J Bäckemo; Reinthaler, M; Lendlein, A; Jung, F

    2016-01-01

    Polymer-based microparticles are applied as non-thrombogenic or thrombogenic materials in a wide variety of intra- or extra-corporeal medical devices. As demanded by the regulatory agencies, the hemocompatibility of these blood contacting biomaterials has to be evaluated in vitro to ensure that the particle systems appropriately fulfill the envisioned function without causing undesired events such as thrombosis or inflammation. Currently described in vitro assays for hemocompatibility testing of particles comprise tests with different single cell types (e.g. erythrocytes or leukocytes), varying concentrations/dilutions of the used blood cells or whole blood, which are not standardized.Here, we report about an in vitro dynamic test system for studying the hemocompatibility of polymeric microparticles utilizing fresh human whole blood from apparently healthy subjects, collected and processed under standardized conditions. Spherical poly(ether imide) microparticles with an average diameter of 140±30 μm were utilized as model systems. Reported as candidate materials for the removal of uremic toxins, these microparticles are anticipated to facilitate optimal flow conditions in a dialyzer with minimal backflow and blood cell damage. Pristine (PEI) and potassium hydroxide (PEI-KOH) functionalized microparticles exhibited similarly nanoporous surfaces (PEI: ØExternal pore = 90±60 nm; PEI-KOH ØExternal pore = 150±130 nm) but varying water wettabilities (PEI: θadv = 112±10° PEI-KOH θadv = 60±2°). The nanoporosity of the microparticle surfaces allows the exchange of toxic solutes from blood towards the interconnective pores in the particle core, while an immigration of the substantially larger blood cells is inhibited.Sterilized PEI microparticles were incorporated -air-free -in a syringe-based test system and exposed to whole blood for 60 minutes under gentle agitation. Thereafter, thrombi formation on the particles surfaces were analyzed

  12. Radionuclide carrier

    International Nuclear Information System (INIS)

    Hartman, F.A.; Kretschmar, H.C.; Tofe, A.J.

    1978-01-01

    A physiologically acceptable particulate radionuclide carrier is described. It comprises a modified anionic starch derivative with 0.1% to 1.5% by weight of a reducing agent and 1 to 20% by weight of anionic substituents

  13. Carrier Screening

    Science.gov (United States)

    ... How accurate is carrier screening? No test is perfect. In a small number of cases, test results ... in which an egg is removed from a woman’s ovary, fertilized in a laboratory with the man’s ...

  14. Duchenne muscular dystrophy carriers

    International Nuclear Information System (INIS)

    Matsumura, K.; Nakano, I.

    1989-01-01

    By means of magnetic resonance imaging (MRI), the proton spin-lattice relaxation times (T1 values) of the skeletal muscles were measured in Duchenne muscular dystrophy (DMD) carriers and normal controls. The bound water fraction (BWF) was calculated from the T1 values obtained, according to the fast proton diffusion model. In the DMD carriers, T1 values of the gluteus maximus and quadriceps femoris muscles were significantly higher, and BWFs of these muscles were significantly lower than in normal control. Degenerative muscular changes accompanied by interstitial edema were presumed responsible for this abnormality. No correlation was observed between the muscle T1 and serum creatine kinase values. The present study showed that MRI could be a useful method for studying the dynamic state of water in both normal and pathological skeletal muscles. Its possible utility for DMD carrier detection was discussed briefly. (orig.)

  15. XPS and Raman study of zinc containing silica microparticles loaded with insulin

    Energy Technology Data Exchange (ETDEWEB)

    Vanea, E.; Simon, V., E-mail: viorica.simon@phys.ubbcluj.ro

    2013-09-01

    Zinc–silica microparticles obtained by sol–gel method solely or by combining sol–gel chemistry with freeze-drying and spray-drying procedures were explored as potential insulin drug delivery carriers for their improved loading efficiency. Zinc containing silica hosts of different specific surface area and mean pore volume loaded with insulin under similar conditions were investigated by X-ray photoelectron spectroscopy (XPS) and confocal micro-Raman spectroscopy in order to assess the insulin adherence to these matrices and the biologically active state of the insulin after embedding.

  16. Innovation in detection of microparticles and exosomes

    NARCIS (Netherlands)

    van der Pol, E.; Coumans, F.; Varga, Z.; Krumrey, M.; Nieuwland, R.

    2013-01-01

    Cell-derived or extracellular vesicles, including microparticles and exosomes, are abundantly present in body fluids such as blood. Although such vesicles have gained strong clinical and scientific interest, their detection is difficult because many vesicles are extremely small with a diameter of

  17. Microparticles and Exosomes in Gynecologic Neoplasias

    NARCIS (Netherlands)

    Nieuwland, Rienk; van der Post, Joris A. M.; Lok Gemma, Christianne A. R.; Kenter, G.; Sturk, Augueste

    2010-01-01

    This review presents an overview of the functions of microparticles and exosomes in gynecologic neoplasias. Growing evidence suggests that vesicles released from cancer cells in gynecologic malignancies contribute to the hypercoagulable state of these patients and contribute to tumor progression by

  18. Microparticles in high-voltage accelerator tubes

    International Nuclear Information System (INIS)

    Griffith, G.L.; Eastham, D.A.

    1979-01-01

    Microparticles with radii greater than 2 μm have been observed in a high voltage vacuum accelerator tube. The charge acquired by most of the particles is similar to the contact charging of a conducting sphere on a plane. (author)

  19. Heterogeneous membranes filled with hypercrosslinked microparticle adsorbent

    Czech Academy of Sciences Publication Activity Database

    Hradil, Jiří; Krystl, V.; Hrabánek, P.; Bernauer, B.; Kočiřík, Milan

    2005-01-01

    Roč. 65, 1-2 (2005), s. 57-68 ISSN 1381-5148 R&D Projects: GA ČR GA104/03/0680 Institutional research plan: CEZ:AV0Z40500505 Keywords : heterogeneous membranes * hypercrosslinked adsorbent * microparticle s Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.565, year: 2005

  20. Diving with microparticles in acoustic fields

    DEFF Research Database (Denmark)

    2012-01-01

    Sound can move particles. A good example of this phenomenon is the Chladni plate, in which an acoustic wave is induced in a metallic plate and particles migrate to the nodes of the acoustic wave. For several years, acoustophoresis has been used to manipulate microparticles in microscopic scales...

  1. Cisplatin-Loaded Porous Si Microparticles Capped by Electroless Deposition of Platinum

    Science.gov (United States)

    Park, Jennifer S.; Kinsella, Joseph M.; Jandial, Danielle D.; Howell, Stephen B.

    2012-01-01

    The loading and release of the anti-cancer drug platinum cis-dichlorodiamine (cisplatin) from mesoporous silicon (pSi) microparticles is studied. The pSi microparticles are modified with 1-dodecene or with 1,12-undecylenic acid by hydrosilylation, and each modified pSi material acts as a reducing agent, forming a deposit of Pt on its surface that nucleates further deposition, capping the mesoporous structure and trapping free (unreduced) cisplatin within. Slow oxidation and hydrolytic dissolution of the Si/SiO2 matrix in buffer solution or in culture medium leads to the release of drugs from the microparticles. The drug-loaded particles show significantly greater toxicity toward human ovarian cancer cells (in vitro), relative to an equivalent quantity of free cisplatin. This result is consistent with the mechanism of drug release, which generates locally high concentrations of the drug in the vicinity of the degrading particles. Control assays with pSi particles loaded in a similar manner with the therapeutically inactive trans isomer of the platinum drug, and with pSi particles containing no drug, result in low cellular toxicity. A hydrophobic prodrug, cis,trans,cis-[Pt(NH3)2(O2C(CH2)8CH3)2Cl2], is loaded into the pSi films from chloroform without concomitant reduction of the pSi carrier. PMID:21630444

  2. In vitro and in vivo antitumor effects of doxorubicin loaded with bacterial magnetosomes (DBMs) on H22 cells: the magnetic bio-nanoparticles as drug carriers.

    Science.gov (United States)

    Sun, Jian-Bo; Duan, Jin-Hong; Dai, Shun-Ling; Ren, Jun; Zhang, Yan-Dong; Tian, Jie-Sheng; Li, Ying

    2007-12-08

    Hepatocellular carcinoma (HCC) is the most common form of cancer although effective therapeutic strategy especially targeted therapy is lacking. We recently employed bacterial magnetosomes (BMs) as the magnetic-targeted drug carrier and found an antitumor effect of doxorubicin (DOX)-loaded BMs (DBMs) in EMT-6 and HL60 cell lines. The aim of this study was to evaluate the in vitro and in vivo anti-neoplastic effects of DBMs on hepatic cancer. DBMs, DOX and BMs displayed tumor suppression rates of 86.8%, 78.6% and 4.3%, respectively, in H22 cell-bearing mice. The mortality rates following administration of DBMs, DOX and BMs were 20%, 80% and 0%, respectively. Pathological examination of hearts and tumors revealed that both DBMs and DOX effectively inhibited tumor growth although DBMs displayed a much lower cardiac toxicity compared with DOX. The DBMs were cytotoxic to H22 cells manifested as inhibition of cell proliferation and c-myc expression, consistent with DOX. The IC(50) of DOX, DBMs and BMs in target cells were 5.309 +/- 0.010, 4.652 +/- 0.256 and 22.106 +/- 3.330 microg/ml, respectively. Our data revealed both in vitro and in vivo antitumor property of DBMs similar to that of DOX. More importantly, the adverse cardiac toxicity was significantly reduced in DBMs compared with DOX. Collectively, our study suggests the therapeutic potential of DBMs in target-therapy against liver cancer.

  3. 4-Aminobenzoic Acid-Coated Maghemite Nanoparticles as Potential Anticancer Drug Magnetic Carriers: A Case Study on Highly Cytotoxic Cisplatin-Like Complexes Involving 7-Azaindoles

    Directory of Open Access Journals (Sweden)

    Pavel Štarha

    2014-01-01

    Full Text Available This study describes a one-pot synthesis of superparamagnetic maghemite-based 4-aminobenzoic acid-coated spherical core-shell nanoparticles (PABA@FeNPs as suitable nanocomposites potentially usable as magnetic carriers for drug delivery. The PABA@FeNPs system was subsequently functionalized by the activated species (1* and 2* of highly in vitro cytotoxic cis-[PtCl2(3Claza2] (1; 3Claza stands for 3-chloro-7-azaindole or cis-[PtCl2(5Braza2] (2; 5Braza stands for 5-bromo-7-azaindole, which were prepared by a silver(I ion assisted dechlorination of the parent dichlorido complexes. The products 1*@PABA@FeNPs and 2*@PABA@FeNPs, as well as an intermediate PABA@FeNPs, were characterized by a combination of various techniques, such as Mössbauer, FTIR and EDS spectroscopy, thermal analysis, SEM and TEM. The results showed that the products consist of well-dispersed maghemite-based nanoparticles of 13 nm average size that represent an easily obtainable system for delivery of highly cytotoxic cisplatin-like complexes in oncological practice.

  4. Heterogeneity in Neutrophil Microparticles Reveals Distinct Proteome and Functional Properties*

    Science.gov (United States)

    Dalli, Jesmond; Montero-Melendez, Trinidad; Norling, Lucy V; Yin, Xiaoke; Hinds, Charles; Haskard, Dorian; Mayr, Manuel; Perretti, Mauro

    2013-01-01

    Altered plasma neutrophil microparticle levels have recently been implicated in a number of vascular and inflammatory diseases, yet our understanding of their actions is very limited. Herein, we investigate the proteome of neutrophil microparticles in order to shed light on their biological actions. Stimulation of human neutrophils, either in suspension or adherent to an endothelial monolayer, led to the production of microparticles containing >400 distinct proteins with only 223 being shared by the two subsets. For instance, postadherent microparticles were enriched in alpha-2 macroglobulin and ceruloplasmin, whereas microparticles produced by neutrophils in suspension were abundant in heat shock 70 kDa protein 1. Annexin A1 and lactotransferrin were expressed in both microparticle subsets. We next determined relative abundance of these proteins in three types of human microparticle samples: healthy volunteer plasma, plasma of septic patients and skin blister exudates finding that these proteins were differentially expressed on neutrophil microparticles from these samples reflecting in part the expression profiles we found in vitro. Functional assessment of the neutrophil microparticles subsets demonstrated that in response to direct stimulation neutrophil microparticles produced reactive oxygen species and leukotriene B4 as well as locomoted toward a chemotactic gradient. Finally, we investigated the actions of the two neutrophil microparticles subsets described herein on target cell responses. Microarray analysis with human primary endothelial cells incubated with either microparticle subset revealed a discrete modulation of endothelial cell gene expression profile. These findings demonstrate that neutrophil microparticles are heterogenous and can deliver packaged information propagating the activation status of the parent cell, potentially exerting novel and fundamental roles both under homeostatic and disease conditions. PMID:23660474

  5. Design of a gelatin microparticle-containing self-microemulsifying formulation for enhanced oral bioavailability of dutasteride

    Directory of Open Access Journals (Sweden)

    Baek I

    2015-06-01

    Full Text Available In-hwan Baek,1,* Eun-Sol Ha,2,* Jin-Wook Yoo,2 Yunjin Jung,2 Min-Soo Kim21College of Pharmacy, Kyungsung University, 2College of Pharmacy, Pusan National University, Busan, Republic of Korea*These authors contributed equally to this workAbstract: In this study, a gelatin microparticle-containing self-microemulsifying formulation (SMF was developed using a spray-drying method to enhance the oral delivery of the poorly water-soluble therapeutic dutasteride. The effect of the amount of gelatin and the type and amount of hydrophilic additives, namely, Gelucire® 44/14, poloxamer 407, sodium lauryl sulfate, Soluplus®, Solutol™ HS15, and D-α-tocopheryl polyethylene glycol 1000 succinate, on the droplet size, dissolution, and oral absorption of dutasteride from the SMF was investigated. Upon dispersion of the gelatin microparticle-containing SMF in water after spray-drying, the mean droplet size of the aqueous dispersion was in the range of 110–137 nm. The in vitro dissolution and recrystallization results showed that gelatin could be used as a solid carrier and recrystallization inhibitor for the SMF of dutasteride. Furthermore, combination of the gelatin microparticle-containing SMF and Soluplus enhanced the dissolution properties and oral absorption of dutasteride. The results of our study suggest that the gelatin microparticle-containing SMF in combination with Soluplus could be useful to enhance the oral absorption of dutasteride.Keywords: dissolution, solubility, bioavailability, dutasteride

  6. Hybrid calcium carbonate/polymer microparticles containing silver nanoparticles as antibacterial agents

    Energy Technology Data Exchange (ETDEWEB)

    Dlugosz, Maciej; Bulwan, Maria; Kania, Gabriela; Nowakowska, Maria; Zapotoczny, Szczepan, E-mail: zapotocz@chemia.uj.edu.pl [Jagiellonian University, Faculty of Chemistry (Poland)

    2012-12-15

    We report here on synthesis and characterization of novel hybrid material consisting of silver nanoparticles (nAgs) embedded in calcium carbonate microparticles ({mu}-CaCO{sub 3}) serving as carriers for sustained release. nAgs are commonly used as antimicrobial agents in many commercial products (textiles, cosmetics, and drugs). Although they are considered to be safe, their interactions with human organisms are still not fully understood; therefore it is important to apply them with caution and limit their presence in the environment. The synthesis of the new material was based on the co-precipitation of CaCO{sub 3} and nAg in the presence of poly(sodium 4-styrenesulfonate). Such designed system enables sustained release of nAg to the environment. This hybrid colloidal material (nAg/{mu}-CaCO{sub 3}) was characterized by microscopic and spectroscopic methods. The release of nAg from {mu}-CaCO{sub 3} microparticles was followed in water at various pH values. Microbiological tests confirmed the effectiveness of these microparticles as an antibacterial agent. Importantly, the material can be stored as a dry powder and subsequently re-suspended in water without the risk of losing its antimicrobial activity. nAg/{mu}-CaCO{sub 3} was applied here to insure bacteriostatic properties of down feathers that may significantly prolong their lifetime in typical applications. Such microparticles may be also used as, e.g., components of coatings and paints protecting various surfaces against microorganism colonization.

  7. Effect of the levitating microparticle cloud on radiofrequency argon plasma

    International Nuclear Information System (INIS)

    Mitic, S.; Pustylnik, M. Y.; Klumov, B. A.; Morfill, G. E.

    2010-01-01

    The effect of a levitating cloud of microparticles on the parameters of a radiofrequency (RF) plasma has been studied by means of two experimental techniques. Axial distributions of 1s excited states of argon were measured by a self-absorption method. A correction of a standard self-absorption method for the extinction of the light by the levitating microparticles is proposed. In addition the electron temperature was estimated using the optical emission spectroscopy. Measurements at the same discharge conditions in a microparticle-free discharge and discharge, containing a cloud of levitating microparticles, revealed the non-local influence of the microparticle cloud on the discharge plasma. The most probable cause of this influence is the disturbance of the ionization balance by the levitating microparticles.

  8. Development of a novel and customizable two-solution mixing type spray nozzle for one-step preparation of nanoparticle-containing microparticles.

    Science.gov (United States)

    Ozeki, Tetsuya; Akiyama, Yusuke; Takahashi, Norimitsu; Tagami, Tatsuaki; Tanaka, Toshiyuki; Fujii, Masashi; Okada, Hiroaki

    2012-01-01

    Production of drug nanoparticles is an effective strategy to enhance solubility and oral absorption of water-insoluble drugs. The handling of drug nanoparticles has been an important issue in drug formulation because nanoparticles easily aggregate each other and redispersion of these particles is very difficult. In the present study, we developed a unique two-solution mixing type spray nozzle that can prepare drug nanoparticles in microparticles in one step without any common solvent and surfactant, and then, the prepared formulation were evaluated. Ethylcellulose (EC) and mannitol (MAN) were used as a model polymer of water-insoluble compound and a water-soluble carrier, respectively. We characterized the EC/MAN microparticles produced by the novel spray nozzle when customizing the nozzle parts to mix EC and MAN solution. Relatively smaller EC nanoparticles (customizable parts in the nozzle. In addition, the core of EC nanoparticles (<50 nm) was also observed by atomic force microscopy. We also found that the mixing time in the nozzle parts affected the size and the standard deviation of EC nanoparticles. These results suggest that the size of EC nanoparticles in MAN microparticles is controllable by using this unique nozzle. After all, we could prepare MAN microparticles containing EC nanoparticles in one step by using the novel nozzle. The drug/MAN microparticles formulation produced by the nozzle may be useful for the handling of drug nanoparticles.

  9. Application of conjugated heparin-albumin microparticles with laser-balloon angioplasty: a potential method for reducing adverse biologic reactivity after angioplasty

    Science.gov (United States)

    Kundu, Sourav K.; McMath, Linda P.; Zaidan, Jonathan T.; Spears, J. Richard

    1991-05-01

    Laser-balloon angioplasty (LBA) may potentially be used for local application of pharmacologically active agents which will reduce thrombogenic and proliferative responses after the angioplasty. In this study, the feasibility of applying covalently conjugated heparin- albumin microparticles onto arterial luminal surface was demonstrated. The covalent linkages were formed by reaction with 1-ethyl-3-dimethyl-aminopropyl-carbodiimide (EDC), and the resultant conjugates were used for preparation of microparticles by employing standard emulsification and heat-crosslinking techniques. The heparin release rate from the microparticles was found to be dependent upon the degree of crosslinking. When a thin coagulum of a suspension of microparticles was formed with heat on a glass surface, the treated surface demonstrated resistance to clot formation in contact with non-anticoagulated blood. A suspension of the microparticles applied during laser-balloon angioplasty onto the luminal surface of dog carotid and femoral arteries showed persistence for up to one week without thrombus formation or occlusion of the vessel. Since the rate of biodegradation is primarily dictated by the extent of crosslinking, an optimal degree of thermal denaturation will permit longer persistence of the carrier while allowing adequate release of the entrapped pharmacologic agent. A variety of antithrombotic and antiinflammatory agents are being considered as candidate bioprotective materials for local application after angioplasty.

  10. Superparamagnetic iron oxide nanoparticles (SPIONs)-loaded Trojan microparticles for targeted aerosol delivery to the lung.

    Science.gov (United States)

    Tewes, Frederic; Ehrhardt, Carsten; Healy, Anne Marie

    2014-01-01

    Targeted aerosol delivery to specific regions of the lung may improve therapeutic efficiency and minimise unwanted side effects. Targeted delivery could potentially be achieved with porous microparticles loaded with superparamagnetic iron oxide nanoparticles (SPIONs)-in combination with a target-directed magnetic gradient field. The aim of this study was to formulate and evaluate the aerodynamic properties of SPIONs-loaded Trojan microparticles after delivery from a dry powder inhaler. Microparticles made of SPIONs, PEG and hydroxypropyl-β-cyclodextrin (HPβCD) were formulated by spray drying and characterised by various physicochemical methods. Aerodynamic properties were evaluated using a next generation cascade impactor (NGI), with or without a magnet positioned at stage 2. Mixing appropriate proportions of SPIONs, PEG and HPβCD allowed Trojan microparticle to be formulated. These particles had a median geometric diameter of 2.8±0.3μm and were shown to be sensitive to the magnetic field induced by a magnet having a maximum energy product of 413.8kJ/m(3). However, these particles, characterised by a mass median aerodynamic diameter (MMAD) of 10.2±2.0μm, were considered to be not inhalable. The poor aerodynamic properties resulted from aggregation of the particles. The addition of (NH4)2CO3 and magnesium stearate (MgST) to the formulation improved the aerodynamic properties of the Trojan particles and resulted in a MMAD of 2.2±0.8μm. In the presence of a magnetic field on stage 2 of the NGI, the amount of particles deposited at this stage increased 4-fold from 4.8±0.7% to 19.5±3.3%. These Trojan particles appeared highly sensitive to the magnetic field and their deposition on most of the stages of the NGI was changed in the presence compared to the absence of the magnet. If loaded with a pharmaceutical active ingredient, these particles may be useful for treating localised lung disease such as cancer nodules or bacterial infectious foci. Copyright

  11. Thermal History Using Microparticle Trap Luminescence

    Science.gov (United States)

    2012-06-01

    the size and shape of bacterial or viral agents and dispersed in a burst vessel . After the test, luminescence from the microparticles is measured to...platinum resistor sputtered on 1 nm adhesion layer of chrome, in turn on a 200nm LPCVD nitride; silicon wet -etching makes this a platform suspended...increased to 500°C until combustion occurred (- 7 min). The remaining powder was collected, crushed in a agate mortar, and annealed (typically at 900

  12. Coherent beam combination via microparticle plasma modes

    International Nuclear Information System (INIS)

    Rogovin, D.; Shen, T.P.

    1988-01-01

    Recently, there have been interesting observations and calculations on phase conjugation via degenerate four-wave mixing in gold colloids. The generation of phase conjugate radiation in these media arises from and reflects the creation of static index grating imposed on the electronic wave functions within the microparticles. These encouraging findings motivate us to consider the possibility of generating moving index gratings in these media with possible applications to coherent beam combination

  13. Endothelial microparticles: Sophisticated vesicles modulating vascular function

    Science.gov (United States)

    Curtis, Anne M; Edelberg, Jay; Jonas, Rebecca; Rogers, Wade T; Moore, Jonni S; Syed, Wajihuddin; Mohler, Emile R

    2015-01-01

    Endothelial microparticles (EMPs) belong to a family of extracellular vesicles that are dynamic, mobile, biological effectors capable of mediating vascular physiology and function. The release of EMPs can impart autocrine and paracrine effects on target cells through surface interaction, cellular fusion, and, possibly, the delivery of intra-vesicular cargo. A greater understanding of the formation, composition, and function of EMPs will broaden our understanding of endothelial communication and may expose new pathways amenable for therapeutic manipulation. PMID:23892447

  14. SIMS depth profile analysis of environmental microparticles

    International Nuclear Information System (INIS)

    Konarski, P.

    2000-01-01

    Environmental and technological research demands chemical characterization of aerosol particles so minute in size, that conventional methods for bulk analyses are simply not applicable. In this work novel application of secondary ion mass spectrometry (SIMS) for characterization of microparticles suspended in atmosphere of the working environment of glass plant Thomson Polkolor, Piaseczno and steelworks Huta Sendzimira, Cracow is presented. The new technique based on sample rotation in depth profile analysis of sub-micrometer particulate material was performed on SAJW-02 analyser equipped with Balzers 16 mm quadrupole spectrometer and sample rotation manipulator using 5 keV Ar + and O 2 + ion beams. The results were compared with the standard method used on ims-3f Cameca analyser 12 keV O 2 + ion beam. Grain size distributions of aerosol microparticles were estimated using eight-stage cascade impactor with particle size range of 0.2 μm to 15 μm. Elemental concentration and crystalline structure of the collected dust particles were performed using spark source mass spectrometry and X-ray diffraction methods. SIMS depth profile analysis shows that sub-micrometer particles do not have uniform morphology, The core-shell structure has been observed for particles collected in both factories. Presented models show that the steelworks particles consists mainly of iron and manganese cores. At the shells of these microparticles :lead, chlorine and fluorine are found. The cores of glass plant submicrometer particles consists mainly of lead-zirconium glass covered by a shell containing carbon and copper. Sample rotation technique applied SIMS appears to be an effective tool for environmental microparticle morphology studies. (author)

  15. Circulating procoagulant microparticles in cancer patients

    OpenAIRE

    Thaler, Johannes; Ay, Cihan; Weinstabl, Harald; Dunkler, Daniela; Simanek, Ralph; Vormittag, Rainer; Freyssinet, Jean-Marie; Zielinski, Christoph; Pabinger, Ingrid

    2010-01-01

    Abstract Accumulating evidence indicates that microparticles (MPs) are important mediators of the interaction between cancer and the hemostatic system. We conducted a large prospective cohort study to determine whether the number of circulating procoagulant MPs is elevated in cancer patients and whether the elevated MP levels are predictive of occurrence of venous thrombembolism (VTE). We analyzed plasma samples of 728 cancer patients from the ongoing prospective observational Vien...

  16. Detection of microparticles in dynamic processes

    International Nuclear Information System (INIS)

    Ten, K A; Pruuel, E R; Kashkarov, A O; Rubtsov, I A; Shechtman, L I; Zhulanov, V V; Tolochko, B P; Rykovanov, G N; Muzyrya, A K; Smirnov, E B; Stolbikov, M Yu; Prosvirnin, K M

    2016-01-01

    When a metal plate is subjected to a strong shock impact, its free surface emits a flow of particles of different sizes (shock-wave “dusting”). Traditionally, the process of dusting is investigated by the methods of pulsed x-ray or piezoelectric sensor or via an optical technique. The particle size ranges from a few microns to hundreds of microns. The flow is assumed to include also finer particles, which cannot be detected with the existing methods yet. On the accelerator complex VEPP-3-VEPP-4 at the BINP there are two experiment stations for research on fast processes, including explosion ones. The stations enable measurement of both passed radiation (absorption) and small-angle x-ray scattering on synchrotron radiation (SR). Radiation is detected with a precision high-speed detector DIMEX. The detector has an internal memory of 32 frames, which enables recording of the dynamics of the process (shooting of movies) with intervals of 250 ns to 2 μ s. Flows of nano- and microparticles from free surfaces of various materials (copper and tin) have been examined. Microparticle flows were emitted from grooves of 50-200 μ s in size and joints (gaps) between metal parts. With the soft x-ray spectrum of SR one can explore the dynamics of a single microjet of micron size. The dynamics of density distribution along micro jets were determined. Under a shock wave (∼ 60 GPa) acting on tin disks, flows of microparticles from a smooth surface were recorded. (paper)

  17. Cardiac involvement in female Duchenne and Becker muscular dystrophy carriers in comparison to their first-degree male relatives: a comparative cardiovascular magnetic resonance study.

    Science.gov (United States)

    Florian, Anca; Rösch, Sabine; Bietenbeck, Michael; Engelen, Markus; Stypmann, Jörg; Waltenberger, Johannes; Sechtem, Udo; Yilmaz, Ali

    2016-03-01

    Duchenne (DMD) and Becker (BMD) muscular dystrophies are X-linked recessive disorders associated with both skeletal myopathy and progressive cardiomyopathy in males. Female DMD/BMD carriers (DMDc/BMDc) are mostly free of skeletal muscle symptoms, but they are also prone to cardiomyopathy. The aim of the current study was to characterize the frequency, pattern, and extent of cardiomyopathy in female DMD/BMD carriers (DMDc/BMDc) in comparison to their first-degree male MD relatives. Thirty-six (age 44 ± 14 years) female MD carriers (20 DMDc and 16 BMDc) constituted the 'MD carrier group' and were prospectively enrolled. All MD carriers underwent a complete CMR study comprising cine- and late gadolinium enhancement (LGE) imaging. In 22 of these women ('female MD carrier comparison group', 7 DMD and 15 BMD), at least one first-degree male relative with a previously established diagnosis of MD underwent the same CMR protocol and was assigned to the 'male MD comparison group' (n = 24, 6 DMD and 18 BMD). In the total MD carrier group, 17 (47%) MD carriers had at least one pathological CMR finding [5 (14%) with a reduced left ventricular ejection fraction (LV-EF) and 16 (44%) with the presence of LGE]. All LGE-positive patients (n = 16) showed non-ischaemic LGE with subepicardial involvement of the LV lateral free wall being the most frequent pattern (13/16, 81%). Compared with BMDc, DMDc demonstrated more frequently a pathological CMR result (65 vs. 19%; P = 0.008)--in spite of being significantly younger (40 ± 11 vs. 50 ± 16 years, P = 0.038). In the male MD comparison group, the same LGE pattern as in female carriers was seen, but with a significantly higher prevalence of cardiac abnormalities compared with their female carrier relatives constituting the female MD comparison group (75 vs. 27%; P = 0.003). Cardiac involvement is a frequent finding in female carriers of DMD, but less frequently observed in carriers of BMD. Those DMDc and BMDc with cardiac involvement

  18. Fabrication of chitosan microparticles loaded in chitosan and poly

    Indian Academy of Sciences (India)

    In recent decades, the use of microparticle-mediated drug delivery is widely applied in the field of biomedicalapplication. Here, we report the new dressing material with ciprofloxacin-loaded chitosan microparticle (CMP) impregnatedin chitosan (CH) and poly(vinyl alcohol) (PVA) scaffold for effective delivery of drug in a ...

  19. Dynamic release and clearance of circulating microparticles during cardiac stress.

    Science.gov (United States)

    Augustine, Daniel; Ayers, Lisa V; Lima, Eduardo; Newton, Laura; Lewandowski, Adam J; Davis, Esther F; Ferry, Berne; Leeson, Paul

    2014-01-03

    Microparticles are cell-derived membrane vesicles, relevant to a range of biological responses and known to be elevated in cardiovascular disease. To investigate microparticle release during cardiac stress and how this response differs in those with vascular disease. We measured a comprehensive panel of circulating cell-derived microparticles by a standardized flow cytometric protocol in 119 patients referred for stress echocardiography. Procoagulant, platelet, erythrocyte, and endothelial but not leukocyte, granulocyte, or monocyte-derived microparticles were elevated immediately after a standardized dobutamine stress echocardiogram and decreased after 1 hour. Twenty-five patients developed stress-induced wall motion abnormalities suggestive of myocardial ischemia. They had similar baseline microparticle levels to those who did not develop ischemia, but, interestingly, their microparticle levels did not change during stress. Furthermore, no stress-induced increase was observed in those without inducible ischemia but with a history of vascular disease. Fourteen patients subsequently underwent coronary angiography. A microparticle rise during stress echocardiography had occurred only in those with normal coronary arteries. Procoagulant, platelet, erythrocyte, and endothelial microparticles are released during cardiac stress and then clear from the circulation during the next hour. This stress-induced rise seems to be a normal physiological response that is diminished in those with vascular disease.

  20. Cyclosporine Induces Endothelial Cell Release of Complement-Activating Microparticles

    Science.gov (United States)

    Renner, Brandon; Klawitter, Jelena; Goldberg, Ryan; McCullough, James W.; Ferreira, Viviana P.; Cooper, James E.; Christians, Uwe

    2013-01-01

    Defective control of the alternative pathway of complement is an important risk factor for several renal diseases, including atypical hemolytic uremic syndrome. Infections, drugs, pregnancy, and hemodynamic insults can trigger episodes of atypical hemolytic uremic syndrome in susceptible patients. Although the mechanisms linking these clinical events with disease flares are unknown, recent work has revealed that each of these clinical conditions causes cells to release microparticles. We hypothesized that microparticles released from injured endothelial cells promote intrarenal complement activation. Calcineurin inhibitors cause vascular and renal injury and can trigger hemolytic uremic syndrome. Here, we show that endothelial cells exposed to cyclosporine in vitro and in vivo release microparticles that activate the alternative pathway of complement. Cyclosporine-induced microparticles caused injury to bystander endothelial cells and are associated with complement-mediated injury of the kidneys and vasculature in cyclosporine-treated mice. Cyclosporine-induced microparticles did not bind factor H, an alternative pathway regulatory protein present in plasma, explaining their complement-activating phenotype. Finally, we found that in renal transplant patients, the number of endothelial microparticles in plasma increases 2 weeks after starting tacrolimus, and treatment with tacrolimus associated with increased C3 deposition on endothelial microparticles in the plasma of some patients. These results suggest that injury-associated release of endothelial microparticles is an important mechanism by which systemic insults trigger intravascular complement activation and complement-dependent renal diseases. PMID:24092930

  1. Evaluating conditions for the formation of chitosan/gelatin microparticles

    Directory of Open Access Journals (Sweden)

    Marcia C. Silva

    2009-06-01

    Full Text Available Chitosan/gelatin microparticles were prepared by complex coacervation. Three chitosan (CH samples, with different acetylation degrees and intrinsic viscosities, were used together with commercial gelatin (G samples. Microparticles formation was investigated at various CH/G ratios, within the pH range of 3.5 to 6.0. Reactions were carried out at 40 and 60 ºC, for 2, 4, and 6 hours. Turbidity measurements performed at 633 nm were used to monitor the process. The resulting curves revealed maximum values, which were correlated to the glucosamine content of CH samples. After isolation, yields were determined, and the microparticles were characterized by infrared spectroscopy (FTIR and thermogravimetry (TGA. Both techniques evidenced the formation of coacervate microparticles. The highest yields in microparticles were determined for the system comprising the CH sample with the lowest degree of acetylation and intrinsic viscosity, and the gelatin sample with the lowest bloom strength.

  2. Delivery of chemotherapeutic drugs in tumour cell-derived microparticles.

    Science.gov (United States)

    Tang, Ke; Zhang, Yi; Zhang, Huafeng; Xu, Pingwei; Liu, Jing; Ma, Jingwei; Lv, Meng; Li, Dapeng; Katirai, Foad; Shen, Guan-Xin; Zhang, Guimei; Feng, Zuo-Hua; Ye, Duyun; Huang, Bo

    2012-01-01

    Cellular microparticles are vesicular plasma membrane fragments with a diameter of 100-1,000 nanometres that are shed by cells in response to various physiological and artificial stimuli. Here we demonstrate that tumour cell-derived microparticles can be used as vectors to deliver chemotherapeutic drugs. We show that tumour cells incubated with chemotherapeutic drugs package these drugs into microparticles, which can be collected and used to effectively kill tumour cells in murine tumour models without typical side effects. We describe several mechanisms involved in this process, including uptake of drug-containing microparticles by tumour cells, synthesis of additional drug-packaging microparticles by these cells that contribute to the cytotoxic effect and the inhibition of drug efflux from tumour cells. This study highlights a novel drug delivery strategy with potential clinical application.

  3. Fission product release from HTGR coated microparticles and fuel elements

    International Nuclear Information System (INIS)

    Gusev, A.A.; Deryugin, A.I.; Lyutikov, R.A.; Chernikov, A.S.

    1991-01-01

    The article presents the results of the investigation of fission products release from microparticles with UO 2 core and five-layer HII PyC- and SiC base protection layers of TRICO type as well as from spherical fuel elements based thereon. It is shown that relative release of short-lived xenon and crypton from microparticles does not exceed (2-3) 10 -7 . The release of gaseous fission products from fuel elements containing no damaged coated microparticles, is primarily determined by the contamination of matrix graphite with fuel. An analytical dependence is derived, the dependence described the relation between structural parameters of coated microparticles, irradiation conditions and fuel burnup at which depressurization of coated microparticles starts

  4. SU-8 micropatterning for microfluidic droplet and microparticle focusing

    International Nuclear Information System (INIS)

    Debuisson, Damien; Senez, Vincent; Arscott, Steve

    2011-01-01

    We demonstrate micropatterned surfaces consisting of concentric circles and spirals which can focus an evaporating sessile droplet to a specific location on a surface. We also study the micropattern geometry to focus microparticles contained within the droplet. The micropatterned surfaces are fabricated using the photoresist SU-8. Our process enables the modification of the surface wetting via the formation of smooth trench-like defects in the SU-8 which define the micropatterns; the geometry of these micropatterns determines the droplet/microparticle focusing. It is clearly shown that the introduction of small gaps into the micropatterns promotes microparticle centring due to the modification of the depinning angle of the droplet. We also show that the use of spiral micropatterns promotes microparticle centring. Finally, microparticle focusing can be enhanced by modification of surface wetting via the addition of a thin fluorocarbon hydrophobic layer onto the SU-8

  5. Cell-derived microparticles in haemostasis and vascular medicine.

    Science.gov (United States)

    Burnier, Laurent; Fontana, Pierre; Kwak, Brenda R; Angelillo-Scherrer, Anne

    2009-03-01

    Considerable interest for cell-derived microparticles has emerged, pointing out their essential role in haemostatic response and their potential as disease markers, but also their implication in a wide range of physiological and pathological processes. They derive from different cell types including platelets - the main source of microparticles - but also from red blood cells, leukocytes and endothelial cells, and they circulate in blood. Despite difficulties encountered in analyzing them and disparities of results obtained with a wide range of methods, microparticle generation processes are now better understood. However, a generally admitted definition of microparticles is currently lacking. For all these reasons we decided to review the literature regarding microparticles in their widest definition, including ectosomes and exosomes, and to focus mainly on their role in haemostasis and vascular medicine.

  6. Aircraft Carriers

    DEFF Research Database (Denmark)

    Nødskov, Kim; Kværnø, Ole

    as their purchases of aircraft carrier systems, makes it more than likely that the country is preparing such an acquisition. China has territorial disputes in the South China Sea over the Spratly Islands and is also worried about the security of its sea lines of communications, by which China transports the majority......, submarines, aircraft and helicopters, is not likely to be fully operational and war-capable until 2020, given the fact that China is starting from a clean sheet of paper. The United States of America (USA), the United Kingdom (UK), Russia and India are currently building or have made decisions to build new...

  7. Technical note: a noninvasive method for measuring mammary apoptosis and epithelial cell activation in dairy animals using microparticles extracted from milk.

    Science.gov (United States)

    Pollott, G E; Wilson, K; Jerram, L; Fowkes, R C; Lawson, C

    2014-01-01

    Milk production from dairy animals has been described in terms of 3 processes: the increase in secretory cell numbers in late pregnancy and early lactation, secretion rate of milk per cell, and the decline in cell numbers as lactation progresses. This latter process is thought to be determined by the level of programmed cell death (apoptosis) found in the animal. Until now, apoptosis has been measured by taking udder biopsies, using magnetic resonance imaging scans, or using animals postmortem. This paper describes an alternative, noninvasive method for estimating apoptosis by measuring microparticles in milk samples. Microparticles are the product of several processes in dairy animals, including apoptosis. Milk samples from 12 Holstein cows, at or past peak lactation, were collected at 5 monthly samplings. The samples (n=57) were used to measure the number of microparticles and calculate microparticle density for 4 metrics: annexin V positive and merocyanine 540 dye positive, for both and total particles, in both whole milk (WM) and spun milk. Various measures of milk production were also recorded for the 12 cows, including daily milk yield, fat and protein percentage in the milk, somatic cell count, and the days in milk when the samples were taken. A high correlation was found between the 4 WM microparticle densities and days in milk (0.46 to 0.64), and a moderate correlation between WM microparticle densities and daily milk yield (-0.33 to -0.44). No significant relationships were found involving spun milk samples, somatic cell count, or fat and protein percentage. General linear model analyses revealed differences between cows for both level of microparticle density and its rate of change in late lactation. Persistency of lactation was also found to be correlated with the WM microparticle traits (-0.65 to -0.32). As apoptosis is likely to be the major contributor to microparticle numbers in late lactation, this work found a noninvasive method for estimating

  8. Acoustic radiation- and streaming-induced microparticle velocities determined by microparticle image velocimetry in an ultrasound symmetry plane

    DEFF Research Database (Denmark)

    Barnkob, Rune; Augustsson, Per; Laurell, Thomas

    2012-01-01

    We present microparticle image velocimetry measurements of suspended microparticles of diameters from 0.6 to 10μm undergoing acoustophoresis in an ultrasound symmetry plane in a microchannel. The motion of the smallest particles is dominated by the Stokes drag from the induced acoustic streaming...

  9. CIRCULATING MICROPARTICLES IN PATIENTS WITH ANTIPHOSPHOLIPID ANTIBODIES: CHARACTERIZATION AND ASSOCIATIONS

    Science.gov (United States)

    Chaturvedi, Shruti; Cockrell, Erin; Espinola, Ricardo; Hsi, Linda; Fulton, Stacey; Khan, Mohammad; Li, Liang; Fonseca, Fabio; Kundu, Suman; McCrae, Keith R.

    2014-01-01

    The antiphospholipid syndrome is characterized by venous or arterial thrombosis and/or recurrent fetal loss in the presence of circulating antiphospholipid antibodies. These antibodies cause activation of endothelial and other cell types leading to the release of microparticles with procoagulant and pro-inflammatory properties. The aims of this study were to characterize the levels of endothelial cell, monocyte, platelet derived, and tissue factor-bearing microparticles in patients with antiphospholipid antibodies, to determine the association of circulating microparticles with anticardiolipin and anti-β2-glycoprotein antibodies, and to define the cellular origin of microparticles that express tissue factor. Microparticle content within citrated blood from 47 patients with antiphospholipid antibodies and 144 healthy controls was analyzed within 2 hours of venipuncture. Levels of Annexin-V, CD105 and CD144 (endothelial derived), CD41 (platelet derived) and tissue factor positive microparticles were significantly higher in patients than controls. Though levels of CD14 (monocyte-derived) microparticles in patient plasma were not significantly increased, increased levels of CD14 and tissue factor positive microparticles were observed in patients. Levels of microparticles that stained for CD105 and CD144 showed a positive correlation with IgG (R = 0.60, p=0.006) and IgM anti-beta2-glycoprotein I antibodies (R=0.58, p=0.006). The elevation of endothelial and platelet derived microparticles in patients with APS and their correlation with anti-β2-glycoprotein I antibodies suggests a chronic state of vascular cell activation in these individuals and an important role for β2-glycoprotein I in development of the pro-thrombotic state associated with antiphospholipid antibodies. PMID:25467081

  10. Study on the technical parameters of two different systems of RIA performed with solid-phase antibody test tubes prepared with magnetic microparticle covalence conjagation or conventional physical absorption

    International Nuclear Information System (INIS)

    Chen Zhiqiang; Wang Chengmin; Tang Baojun

    2007-01-01

    Objective: To investigate a new method of preparation of solid-phase antibody with flurorescein isothioeynate (FITC)-anti FITC magnetic nanoparticles system (for FT 3 and TSH). Methods: FT 3 and TSH monoclonal antibody IgC was la- belied with FITC. Anti-FITC magnetic mieroparticles was prepared and conjugated with the FITC labelled antibody to form the solid - phase coated test tube for RIA. Solid-phase test tube prepared with the conventional physical absorption method was also used for RIA and the technical parameters of the two systems were compared. Results: For FT 3 , the sensitivity was 0.18pmol/L with the new method and 0.43pmol/L with the conventional method. Other parameters were; intra-CV, 8.96% vs 16.26%; inter-CV, 15.25% vs 18.83%, correlation with PR method r=0.9825 vs r=0.9102. For TSH, sensitivity was 0.061 μIU/ml vs 0.04 μ IU/ml, intra- CV, 7.6% vs 6.92%, inter-CV, 8.55% vs 14.23%, correlation between the new and conventional method, r=0. 9987. TSH RIA was especially rapid with the new technic: 79 min vs 190 min. Conclusion: For FT 3 and TSH RIA, the new method takes much less time with increased homogeniety. (authors)

  11. Endothelial microparticles (EMP in physiology and pathology

    Directory of Open Access Journals (Sweden)

    Ewa Sierko

    2015-08-01

    Full Text Available Endothelial microparticles (EMP are released from endothelial cells (ECs in the process of activation and/or apoptosis. They harbor adhesive molecules, enzymes, receptors and cytoplasmic structures and express a wide range of various constitutive antigens, typical for ECs, at their surface. Under physiological conditions the concentration of EMP in the blood is clinically insignificant. However, it was reported that under pathological conditions EMP concentration in the blood might slightly increase and contribute to blood coagulation, angiogenesis and inflammation. It has been shown that EMP directly and indirectly contribute to the activation of blood coagulation. Endothelial microparticles directly participate in blood coagulation through their surface tissue factor (TF – a major initiator of blood coagulation. Furthermore, EMP exhibit procoagulant potential via expression of negatively charged phospholipids at their surface, which may promote assembly of coagulation enzymes (TF/VII, tenases and prothrombinase complexes, leading to thrombus formation. In addition, they provide a binding surface for coagulation factors: IXa, VIII, Va and IIa. Moreover, it is possible that EMP transfer TF from TF-bearing EMP to activated platelets and monocytes by binding them through adhesion molecules. Also, EMP express von Willebrand factor, which may facilitate platelet aggregation. Apart from their procoagulant properties, it was demonstrated that EMP may express adhesive molecules and metalloproteinases (MMP-2, MMP-9 at their surface and release growth factors, which may contribute to angiogenesis. Additionally, surface presence of C3 and C4 – components of the classical pathway – suggests pro-inflammatory properties of these structures. This article contains a summary of available data on the biology and pathophysiology of endothelial microparticles and their potential role in blood coagulation, angiogenesis and inflammation.

  12. Anti-neutrophil cytoplasmic antibodies stimulate release of neutrophil microparticles.

    LENUS (Irish Health Repository)

    Hong, Ying

    2012-01-01

    The mechanisms by which anti-neutrophil cytoplasmic antibodies (ANCAs) may contribute to the pathogenesis of ANCA-associated vasculitis are not well understood. In this study, both polyclonal ANCAs isolated from patients and chimeric proteinase 3-ANCA induced the release of neutrophil microparticles from primed neutrophils. These microparticles expressed a variety of markers, including the ANCA autoantigens proteinase 3 and myeloperoxidase. They bound endothelial cells via a CD18-mediated mechanism and induced an increase in endothelial intercellular adhesion molecule-1 expression, production of endothelial reactive oxygen species, and release of endothelial IL-6 and IL-8. Removal of the neutrophil microparticles by filtration or inhibition of reactive oxygen species production with antioxidants abolished microparticle-mediated endothelial activation. In addition, these microparticles promoted the generation of thrombin. In vivo, we detected more neutrophil microparticles in the plasma of children with ANCA-associated vasculitis compared with that in healthy controls or those with inactive vasculitis. Taken together, these results support a role for neutrophil microparticles in the pathogenesis of ANCA-associated vasculitis, potentially providing a target for future therapeutics.

  13. Chitosan microparticles for sustaining the topical delivery of minoxidil sulphate.

    Science.gov (United States)

    Gelfuso, Guilherme Martins; Gratieri, Taís; Simão, Patrícia Sper; de Freitas, Luís Alexandre Pedro; Lopez, Renata Fonseca Vianna

    2011-01-01

    Given the hypothesis that microparticles can penetrate the skin barrier along the transfollicular route, this work aimed to obtain and characterise chitosan microparticles loaded with minoxidil sulphate (MXS) and to study their ability to sustain the release of the drug, attempting a further application utilising them in a targeted delivery system for the topical treatment of alopecia. Chitosan microparticles, containing different proportions of MXS/polymer, were prepared by spray drying and were characterised by yield, encapsulation efficiency, size and morphology. Microparticles selected for further studies showed high encapsulation efficiency (∼82%), a mean diameter of 3.0 µm and a spherical morphology without porosities. When suspended in an ethanol/water solution, chitosan microparticles underwent instantaneous swelling, increasing their mean diameter by 90%. Release studies revealed that the chitosan microparticles were able to sustain about three times the release rate of MXS. This feature, combined with suitable size, confers to these microparticles the potential to target and improve topical therapy of alopecia with minoxidil.

  14. Fabrication and characterization of carboxymethyl cellulose novel microparticles for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Gaihre, Bipin [Department of Bioengineering, The University of Toledo, Toledo, OH 43614 (United States); Jayasuriya, Ambalangodage C., E-mail: a.jayasuriya@utoledo.edu [Department of Bioengineering, The University of Toledo, Toledo, OH 43614 (United States); Department of Orthopaedic Surgery, University of Toledo Medical Center, Toledo, OH 43614 (United States)

    2016-12-01

    In this study we developed carboxymethyl cellulose (CMC) microparticles through ionic crosslinking with the aqueous ion complex of zirconium (Zr) and further complexing with chitosan (CS) and determined the physio-chemical and biological properties of these novel microparticles. In order to assess the role of Zr, microparticles were prepared in 5% and 10% (w/v) zirconium tetrachloride solution. Scanning electron microscopy (SEM) with energy dispersive X-ray spectrometer (EDS) results showed that Zr was uniformly distributed on the surface of the microparticles as a result of which uniform groovy surface was obtained. We found that Zr enhances the surface roughness of the microparticles and stability studies showed that it also increases the stability of microparticles in phosphate buffered saline. The crosslinking of anionic CMC with cationic Zr and CS was confirmed by Fourier transform infrared spectroscopy (FTIR) results. The response of murine pre-osteoblasts (OB-6) when cultured with microparticles was investigated. Live/dead cell assay showed that microparticles did not induce any cytotoxic effects as cells were attaching and proliferating on the well plate as well as along the surface of microparticles. In addition, SEM images showed that microparticles support the attachment of cells and they appeared to be directly interacting with the surface of microparticle. Within 10 days of culture most of the top surface of microparticles was covered with a layer of cells indicating that they were proliferating well throughout the surface of microparticles. We observed that Zr enhances the cell attachment and proliferation as more cells were present on microparticles with 10% Zr. These promising results show the potential applications of CMC-Zr microparticles in bone tissue engineering. - Highlights: • Zirconium ions crosslinked carboxymethyl cellulose microparticles were fabricated. • The microparticles were further stabilized by complexation with chitosan.

  15. Fabrication and characterization of carboxymethyl cellulose novel microparticles for bone tissue engineering

    International Nuclear Information System (INIS)

    Gaihre, Bipin; Jayasuriya, Ambalangodage C.

    2016-01-01

    In this study we developed carboxymethyl cellulose (CMC) microparticles through ionic crosslinking with the aqueous ion complex of zirconium (Zr) and further complexing with chitosan (CS) and determined the physio-chemical and biological properties of these novel microparticles. In order to assess the role of Zr, microparticles were prepared in 5% and 10% (w/v) zirconium tetrachloride solution. Scanning electron microscopy (SEM) with energy dispersive X-ray spectrometer (EDS) results showed that Zr was uniformly distributed on the surface of the microparticles as a result of which uniform groovy surface was obtained. We found that Zr enhances the surface roughness of the microparticles and stability studies showed that it also increases the stability of microparticles in phosphate buffered saline. The crosslinking of anionic CMC with cationic Zr and CS was confirmed by Fourier transform infrared spectroscopy (FTIR) results. The response of murine pre-osteoblasts (OB-6) when cultured with microparticles was investigated. Live/dead cell assay showed that microparticles did not induce any cytotoxic effects as cells were attaching and proliferating on the well plate as well as along the surface of microparticles. In addition, SEM images showed that microparticles support the attachment of cells and they appeared to be directly interacting with the surface of microparticle. Within 10 days of culture most of the top surface of microparticles was covered with a layer of cells indicating that they were proliferating well throughout the surface of microparticles. We observed that Zr enhances the cell attachment and proliferation as more cells were present on microparticles with 10% Zr. These promising results show the potential applications of CMC-Zr microparticles in bone tissue engineering. - Highlights: • Zirconium ions crosslinked carboxymethyl cellulose microparticles were fabricated. • The microparticles were further stabilized by complexation with chitosan.

  16. Magnetism of Carbonados

    Science.gov (United States)

    Kletetschka, G.; Taylor, P. T.; Wasilewski, P. J.

    2000-01-01

    Origin of Carbonado is not clear. Magnetism of Carbonado comes from the surface, indicating contemporary formation of both the surface and magnetic carriers. The interior of carbonado is relatively free of magnetic phases.

  17. Stimuli sensitive polymethacrylic acid microparticles (PMAA)--oral insulin delivery.

    Science.gov (United States)

    Victor, Sunita Prem; Sharma, Chandra P

    2002-10-01

    This study investigated polymethacrylic acid (PMAA) microparticles for controlled release of Insulin in oral administration. The microparticles were characterised by scanning electron microscopy (SEM) for morphological studies. The swelling behaviour and drug release profile in various pH media were studied. The % swelling of gels was found to be inversely related to the amount of crosslinker added. Inclusion complex of betaCD and Insulin was studied using polyacrylamide gel electrophoresis (PAGE). Optimum complexation was obtained in the ratio 100 mg betaCD: 200 IU Insulin. The release pattern of Insulin from Insulin-betaCD complex encapsulated PMAA microparticles showed release of Insulin for more than seven hours.

  18. Magnets

    International Nuclear Information System (INIS)

    Young, I.R.

    1984-01-01

    A magnet pole piece for an NMR imaging magnet is made of a plurality of magnetic wires with one end of each wire held in a non-magnetic spacer, the other ends of the wires being brought to a pinch, and connected to a magnetic core. The wires may be embedded in a synthetic resin and the magnetisation and uniformity thereof can be varied by adjusting the density of the wires at the spacer which forms the pole piece. (author)

  19. Disintegration of nano-embedded microparticles after deposition on mucus: A mechanistic study.

    Science.gov (United States)

    Ruge, Christian A; Bohr, Adam; Beck-Broichsitter, Moritz; Nicolas, Valérie; Tsapis, Nicolas; Fattal, Elias

    2016-03-01

    The conversion of colloidal drug carriers/polymeric nanoparticles into dry microparticulate powders (e.g., by spray-drying) is a prominent approach to overcome the aerodynamic limitations of these formulations for delivery via inhalation. However, to what extent such nano-embedded microparticles disintegrate into individual/intact nanoparticles after contacting relevant physiological media has so far not been addressed. Polymeric nanoparticles were spray-dried into nano-embedded microparticles (NEMs) using different amounts of trehalose as embedding matrix excipient. Formulations were characterized and then evaluated for their disintegration behavior after aerosolization onto model mucus. Although a rapid and complete aqueous redispersion was observed for specific excipient/nanoparticle weight ratios (i.e., greater than 1/1), the same formulations revealed no disintegration after deposition onto a static mucus layer. Double-labeled NEMs powders (i.e., dual color staining of polymeric nanoparticles and trehalose) demonstrated rapid matrix dissolution, while the nanoparticle aggregates persisted. When deposited onto agitated mucus, however, sufficient disintegration of NEMs into individual polymeric nanoparticles was observed. These findings indicate that mechanical forces are necessary to overcome the attraction between individual nanoparticles found within the NEMs. Thus, it remains questionable whether the lung mechanics (e.g., breathing, mucociliary clearance) acting on these formulations will contribute to the overall disintegration process. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Bulk manufacture of concentrated oxygen gas-filled microparticles for intravenous oxygen delivery.

    Science.gov (United States)

    Kheir, John N; Polizzotti, Brian D; Thomson, Lindsay M; O'Connell, Daniel W; Black, Katherine J; Lee, Robert W; Wilking, James N; Graham, Adam C; Bell, David C; McGowan, Francis X

    2013-08-01

    Self-assembling, concentrated, lipid-based oxygen microparticles (LOMs) have been developed to administer oxygen gas when injected intravenously, preventing organ injury and death from systemic hypoxemia in animal models. Distinct from blood substitutes, LOMs are a one-way oxygen carrier designed to rescue patients who experience life-threatening hypoxemia, as caused by airway obstruction or severe lung injury. Here, we describe methods to manufacture large quantities of LOMs using an in-line, recycling, high-shear homogenizer, which can create up to 4 liters of microparticle emulsion in 10 minutes, with particles containing a median diameter of 0.93 microns and 60 volume% of gas phase. Using this process, we screen 30 combinations of commonly used excipients for their ability to form stable LOMs. LOMs composed of DSPC and cholesterol in a 1:1 molar ratio are stable for a 100 day observation period, and the number of particles exceeding 10 microns in diameter does not increase over time. When mixed with blood in vitro, LOMs fully oxygenate blood within 3.95 seconds of contact, and do not cause hemolysis or complement activation. LOMs can be manufactured in bulk by high shear homogenization, and appear to have a stability and size profile which merit further testing. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Detection and quantification of microparticles from different cellular lineages using flow cytometry. Evaluation of the impact of secreted phospholipase A2 on microparticle assessment.

    Science.gov (United States)

    Rousseau, Matthieu; Belleannee, Clemence; Duchez, Anne-Claire; Cloutier, Nathalie; Levesque, Tania; Jacques, Frederic; Perron, Jean; Nigrovic, Peter A; Dieude, Melanie; Hebert, Marie-Josee; Gelb, Michael H; Boilard, Eric

    2015-01-01

    Microparticles, also called microvesicles, are submicron extracellular vesicles produced by plasma membrane budding and shedding recognized as key actors in numerous physio(patho)logical processes. Since they can be released by virtually any cell lineages and are retrieved in biological fluids, microparticles appear as potent biomarkers. However, the small dimensions of microparticles and soluble factors present in body fluids can considerably impede their quantification. Here, flow cytometry with improved methodology for microparticle resolution was used to detect microparticles of human and mouse species generated from platelets, red blood cells, endothelial cells, apoptotic thymocytes and cells from the male reproductive tract. A family of soluble proteins, the secreted phospholipases A2 (sPLA2), comprises enzymes concomitantly expressed with microparticles in biological fluids and that catalyze the hydrolysis of membrane phospholipids. As sPLA2 can hydrolyze phosphatidylserine, a phospholipid frequently used to assess microparticles, and might even clear microparticles, we further considered the impact of relevant sPLA2 enzymes, sPLA2 group IIA, V and X, on microparticle quantification. We observed that if enriched in fluids, certain sPLA2 enzymes impair the quantification of microparticles depending on the species studied, the source of microparticles and the means of detection employed (surface phosphatidylserine or protein antigen detection). This study provides analytical considerations for appropriate interpretation of microparticle cytofluorometric measurements in biological samples containing sPLA2 enzymes.

  2. Leukocyte- and endothelial-derived microparticles: a circulating source for fibrinolysis

    Science.gov (United States)

    Lacroix, Romaric; Plawinski, Laurent; Robert, Stéphane; Doeuvre, Loïc; Sabatier, Florence; Martinez de Lizarrondo, Sara; Mezzapesa, Anna; Anfosso, Francine; Leroyer, Aurelie S.; Poullin, Pascale; Jourde, Noémie; Njock, Makon-Sébastien; Boulanger, Chantal M.; Anglés-Cano, Eduardo; Dignat-George, Françoise

    2012-01-01

    Background We recently assigned a new fibrinolytic function to cell-derived microparticles in vitro. In this study we explored the relevance of this novel property of microparticles to the in vivo situation. Design and Methods Circulating microparticles were isolated from the plasma of patients with thrombotic thrombocytopenic purpura or cardiovascular disease and from healthy subjects. Microparticles were also obtained from purified human blood cell subpopulations. The plasminogen activators on microparticles were identified by flow cytometry and enzyme-linked immunosorbent assays; their capacity to generate plasmin was quantified with a chromogenic assay and their fibrinolytic activity was determined by zymography. Results Circulating microparticles isolated from patients generate a range of plasmin activity at their surface. This property was related to a variable content of urokinase-type plasminogen activator and/or tissue plasminogen activator. Using distinct microparticle subpopulations, we demonstrated that plasmin is generated on endothelial and leukocyte microparticles, but not on microparticles of platelet or erythrocyte origin. Leukocyte-derived microparticles bear urokinase-type plasminogen activator and its receptor whereas endothelial microparticles carry tissue plasminogen activator and tissue plasminogen activator/inhibitor complexes. Conclusions Endothelial and leukocyte microparticles, bearing respectively tissue plasminogen activator or urokinase-type plasminogen activator, support a part of the fibrinolytic activity in the circulation which is modulated in pathological settings. Awareness of this blood-borne fibrinolytic activity conveyed by microparticles provides a more comprehensive view of the role of microparticles in the hemostatic equilibrium. PMID:22733025

  3. Development of a Sustainable Release System for a Ranibizumab Biosimilar Using Poly(lactic-co-glycolic acid) Biodegradable Polymer-Based Microparticles as a Platform.

    Science.gov (United States)

    Tanetsugu, Yusuke; Tagami, Tatsuaki; Terukina, Takayuki; Ogawa, Takaya; Ohta, Masato; Ozeki, Tetsuya

    2017-01-01

    Ranibizumab is a humanized monoclonal antibody fragment against vascular endothelial growth factor (VEGF)-A and is widely used to treat age-related macular degeneration (AMD) caused by angiogenesis. Ranibizumab has a short half-life in the eye due to its low molecular weight and susceptibility to proteolysis. Monthly intravitreal injection of a large amount of ranibizumab formulation is a burden for both patients and medical staff. We therefore sought to develop a sustainable release system for treating the eye with ranibizumab using a drug carrier. A ranibizumab biosimilar (RB) was incorporated into microparticles of poly(lactic-co-glycolic acid) (PLGA) biodegradable polymer. Ranibizumab was sustainably released from PLGA microparticles (80+% after 3 weeks). Assay of tube formation by endothelial cells indicated that RB released from PLGA microparticles inhibited VEGF-induced tube formation and this tendency was confirmed by a cell proliferation assay. These results indicate that RB-loaded PLGA microparticles are useful for sustainable RB release and suggest the utility of intraocular sustainable release systems for delivering RB site-specifically to AMD patients.

  4. Pluronic-Functionalized Silica-Lipid Hybrid Microparticles: Improving the Oral Delivery of Poorly Water-Soluble Weak Bases.

    Science.gov (United States)

    Rao, Shasha; Richter, Katharina; Nguyen, Tri-Hung; Boyd, Ben J; Porter, Christopher J H; Tan, Angel; Prestidge, Clive A

    2015-12-07

    A Pluronic-functionalized silica-lipid hybrid (Plu-SLH) microparticle system for the oral delivery of poorly water-soluble, weak base drugs is reported for the first time. A highly effective Plu-SLH microparticle system was composed of Labrasol as the lipid phase, Pluronic F127 as the polymeric precipitation inhibitor (PPI), and silica nanoparticles as the solid carrier. For the model drug cinnarizine (CIN), the Plu-SLH delivery system was shown to offer significant biopharmaceutical advantages in comparison with unformulated drug and drug in the silica-lipid hybrid (SLH) system. In vitro two-phase dissolution studies illustrated significantly reduced pH provoked CIN precipitation and an 8- to 14-fold improvement in the extent of dissolution in intestinal conditions. In addition, under simulated intestinal digesting conditions, the Plu-SLH provided approximately three times more drug solubilization than the SLH. Oral administration in rats resulted in superior bioavailability for Plu-SLH microparticles, i.e., 1.6- and 2.1-fold greater than the SLH and the unformulated CIN, respectively. A physical mixture of Pluronic and SLH (Plu&SLH), having the same composition as Plu-SLH, was also evaluated, but showed no significant increase in CIN absorption when compared to unmodified CIN or SLH. This work represents the first study where different methods of incorporating PPI to formulate solid-state lipid-based formulations were compared for the impact on the biopharmaceutical performance. The data suggest that the novel physicochemical properties and structure of the fabricated Plu-SLH microparticle delivery system play an important role in facilitating the synergistic advantage of Labrasol and Pluronic F127 in preventing drug precipitation, and the Plu-SLH provides efficient oral delivery of poorly water-soluble weak bases.

  5. Distinct proteome pathology of circulating microparticles in systemic lupus erythematosus

    DEFF Research Database (Denmark)

    Østergaard, Ole; Nielsen, Christoffer Tandrup; Tanassi, Julia T

    2017-01-01

    BACKGROUND: The pathogenesis of systemic lupus erythematosus (SLE) is poorly understood but has been linked to defective clearance of subcellular particulate material from the circulation. This study investigates the origin, formation, and specificity of circulating microparticles (MPs) in patients...

  6. Drug loading into porous calcium carbonate microparticles by solvent evaporation.

    Science.gov (United States)

    Preisig, Daniel; Haid, David; Varum, Felipe J O; Bravo, Roberto; Alles, Rainer; Huwyler, Jörg; Puchkov, Maxim

    2014-08-01

    Drug loading into porous carriers may improve drug release of poorly water-soluble drugs. However, the widely used impregnation method based on adsorption lacks reproducibility and efficiency for certain compounds. The aim of this study was to evaluate a drug-loading method based on solvent evaporation and crystallization, and to investigate the underlying drug-loading mechanisms. Functionalized calcium carbonate (FCC) microparticles and four drugs with different solubility and permeability properties were selected as model substances to investigate drug loading. Ibuprofen, nifedipine, losartan potassium, and metronidazole benzoate were dissolved in acetone or methanol. After dispersion of FCC, the solvent was removed under reduced pressure. For each model drug, a series of drug loads were produced ranging from 25% to 50% (w/w) in steps of 5% (w/w). Loading efficiency was qualitatively analyzed by scanning electron microscopy (SEM) using the presence of agglomerates and drug crystals as indicators of poor loading efficiency. The particles were further characterized by mercury porosimetry, specific surface area measurements, differential scanning calorimetry, and USP2 dissolution. Drug concentration was determined by HPLC. FCC-drug mixtures containing equivalent drug fractions but without specific loading strategy served as reference samples. SEM analysis revealed high efficiency of pore filling up to a drug load of 40% (w/w). Above this, agglomerates and separate crystals were significantly increased, indicating that the maximum capacity of drug loading was reached. Intraparticle porosity and specific surface area were decreased after drug loading because of pore filling and crystallization on the pore surface. HPLC quantification of drugs taken up by FCC showed only minor drug loss. Dissolution rate of FCC loaded with metronidazole benzoate and nifedipine was faster than the corresponding FCC-drug mixtures, mainly due to surface enlargement, because only small

  7. Droplet-based microfluidic method for synthesis of microparticles

    CSIR Research Space (South Africa)

    Mbanjwa, MB

    2012-10-01

    Full Text Available Droplet-based microfluidics has, in recent years, received increased attention as an important tool for performing numerous methods in modern day chemistry and biology such as the synthesis of hydrogel microparticles. Hydrogels have been used in many..., in recent years, received increased attention as an important tool for performing numerous methods in modern day chemistry and biology, such as synthesis of hydrogel microparticles. CONCLUSION AND OUTLOOK The droplet-based microfluidic method offers...

  8. Carboxymethyl starch/montmorillonite composite microparticles: Properties and controlled release of isoproturon.

    Science.gov (United States)

    Wilpiszewska, Katarzyna; Spychaj, Tadeusz; Paździoch, Waldemar

    2016-01-20

    Preparation of novel high substituted carboxymethyl starch-based microparticles containing sodium montmorillonite (MMT) by crosslinking with Al(3+) was described. For preparing nanocomposite granules carboxymethyl starch (CMS) from native potato starch as well as CMS from amylopectin has been used. The hydrophilic CMS/MMT composite systems were used for herbicide, i.e. isoproturon encapsulation (ca. 75% encapsulation efficiency). The herbicide release rate from CMS/MMT composites in water was significantly reduced when compared to commercial isoproturon: 95% released after ca. 700 h and ca. 24h, respectively. Leaching in soil from composite systems was relatively slower than release in water. After a series of eight irrigations leached about 10% of isoproturon loaded. The CMS/MMT carriers could reduce the potential leaching of herbicide and beneficially reduce pollution of the environment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Preparation of 5-fluorouracil loaded chitosan microparticle and its drug release properties

    Directory of Open Access Journals (Sweden)

    Li Mingming

    2017-01-01

    Full Text Available Chitosan is one kind of good biocompatible polymer and is suitble for drug carriers. Preparation of 5-fluorouracil (5-Fu loaded chitosan (CS particles and in vitro release experiment were performed using ionic crosslinking method with sodium tripolyphosphate (TPP as crosslinker. The optimal preparing parameters were verified by 5-Fu release experiments. The drug loading, and release behavior of drug loaded microparticles in vitro were investigated. The optimal preparation conditions were: the temperature 25°C, the ratio of CS to TPP 5:1, the CS concentration 1.5g/L, stirring speed 650rpm. Under these conditions, the drug loading of particles was up to 45%.

  10. "Thunderstruck": Plasma-Polymer-Coated Porous Silicon Microparticles As a Controlled Drug Delivery System.

    Science.gov (United States)

    McInnes, Steven J P; Michl, Thomas D; Delalat, Bahman; Al-Bataineh, Sameer A; Coad, Bryan R; Vasilev, Krasimir; Griesser, Hans J; Voelcker, Nicolas H

    2016-02-01

    Controlling the release kinetics from a drug carrier is crucial to maintain a drug's therapeutic window. We report the use of biodegradable porous silicon microparticles (pSi MPs) loaded with the anticancer drug camphothecin, followed by a plasma polymer overcoating using a loudspeaker plasma reactor. Homogenous "Teflon-like" coatings were achieved by tumbling the particles by playing AC/DC's song "Thunderstruck". The overcoating resulted in a markedly slower release of the cytotoxic drug, and this effect correlated positively with the plasma polymer coating times, ranging from 2-fold up to more than 100-fold. Ultimately, upon characterizing and verifying pSi MP production, loading, and coating with analytical methods such as time-of-flight secondary ion mass spectrometry, scanning electron microscopy, thermal gravimetry, water contact angle measurements, and fluorescence microscopy, human neuroblastoma cells were challenged with pSi MPs in an in vitro assay, revealing a significant time delay in cell death onset.

  11. Manipulation of magnetic particles in microfluidic volumes

    NARCIS (Netherlands)

    Gao, Y.; Reenen, van A.; Hulsen, M.A.; Jong, de A.M.; Prins, M.W.J.; Toonder, den J.M.J.

    2013-01-01

    This paper reports various ways of field-based manipulation of magnetic colloidal particles to enhance biochemical reactions in lab-on-chip systems [1]. For one (I), we show the possibility to assemble the suspended magnetic micro-particles as tunable re-formable micro-stirrers capable of performing

  12. Effects of microparticle size and Fc density on macrophage phagocytosis.

    Directory of Open Access Journals (Sweden)

    Patricia Pacheco

    Full Text Available Controlled induction of phagocytosis in macrophages offers the ability to therapeutically regulate the immune system as well as improve delivery of chemicals or biologicals for immune processing. Maximizing particle uptake by macrophages through Fc receptor-mediated phagocytosis could lead to new delivery mechanisms in drug or vaccine development. Fc ligand density and particle size were examined independently and in combination in order to optimize and tune the phagocytosis of opsonized microparticles. We show the internalization efficiency of small polystyrene particles (0.5 µm to 2 µm is significantly affected by changes in Fc ligand density, while particles greater than 2 µm show little correlation between internalization and Fc density. We found that while macrophages can efficiently phagocytose a large number of smaller particles, the total volume of phagocytosed particles is maximized through the non-specific uptake of larger microparticles. Therefore, larger microparticles may be more efficient at delivering a greater therapeutic payload to macrophages, but smaller opsonized microparticles can deliver bio-active substances to a greater percentage of the macrophage population. This study is the first to treat as independent variables the physical and biological properties of Fc density and microparticle size that initiate macrophage phagocytosis. Defining the physical and biological parameters that affect phagocytosis efficiency will lead to improved methods of microparticle delivery to macrophages.

  13. Preparation and Characterization of Keratin/Alginate Blend Microparticles

    Directory of Open Access Journals (Sweden)

    Yaowalak Srisuwan

    2018-01-01

    Full Text Available The water-in-oil (W/O emulsification-diffusion method was used for construction of keratin (Ker, alginate (Alg, and Ker/Alg blend microparticles. The Ker, Alg, and Ker/Alg blend solutions were used as the water phase, while ethyl acetate was used as the oil phase. Firstly, different concentrations of Ker solution was used to find suitable content. 1.6% w/v Ker solution was blended with the same concentration of the Alg solution for further microparticle construction. Results from scanning electron microscope analysis show that the microparticles have different shapes: spherical, bowl-like, porous, and hollow, with several sizes depending on the blend ratio. FTIR and TG analyses indicated that the secondary structure and thermal stability of the microparticles were influenced by the Ker/Alg blend ratio. The interaction between functional groups of keratin and alginate was the main factor for both β-sheet structure and Td,max values of the microparticles. The results suggested that Ker/Alg blend microparticles might be applied in many fields by varying the Ker/Alg ratio.

  14. In vitro release kinetics of Tolmetin from tabletted Eudragit microparticles.

    Science.gov (United States)

    Pignatello, R; Consoli, P; Puglisi, G

    2000-01-01

    In a previous paper the preparation has been described, by three different techniques, of microparticles made of Eudragit RS 100 and RL 100 containing a NSAI agent, Tolmetin. Freely flowing microparticles failed to affect significantly the in vitro drug release, which displayed a similar dissolution profile after micro-encapsulation to the free drug powder. Microparticles were then converted into tablets and the effect of compression on drug delivery, as well as that of the presence of co-additives, was studied in the present work. Furthermore, microparticles were also prepared by adding MgO to the polymer matrix, to reduce the sensitivity of the drug to pH changes during its dissolution. Similarly, magnesium stearate was also used for microparticle formation as a droplet stabilizer, in order to reduce particle size and hinder rapid drug release. A mathematical evaluation, by using two semi-empirical equations, was applied to evaluate the influence of dissolution and diffusion phenomena upon drug release from microparticle tablets.

  15. Magnetic separation from superparamagnetic particle suspensions

    International Nuclear Information System (INIS)

    Sinha, Ashok; Ganguly, Ranjan; Puri, Ishwar K.

    2009-01-01

    We investigate the magnetophoretic separation of magnetic microparticles from a non-dilute flow in a microfluidic channel and their subsequent field-induced aggregation under the influence of an externally applied magnetic force. This force induces dipolar interactions between the particles that aid in their separation from the flow. Existing analytical models for dilute suspensions cannot be extended to non-dilute suspensions in which interparticle magnetic interactions play an important role. We therefore conduct a parametric investigation of the mechanics of this problem in a microcapillary flow through simulations and experimental visualization. When a magnetic field is applied, the magnetic microparticles form an aggregate on the channel wall that is influenced by the competition between the holding magnetic force and the aggregate-depleting flow shear force. Microparticle collection in the aggregate increases linearly with increasing magnetic field strength and is characterized by distinct buildup and washaway phases. The collected microparticle volume fraction in an aggregate is found to depend on a single dimensional group that depends upon characteristic system parameters.

  16. Rod-Shaped Magnetite Nano/Microparticles Synthesis at Ambient Temperature

    Directory of Open Access Journals (Sweden)

    Balaprasad Ankamwar

    2013-01-01

    Full Text Available Here, we reported room temperature synthesis of Fe3O4 rod-shaped nano/microparticles by chemical reduction method from FeCl3 precursor and NaBH4 as the reducing agent in the presence of the pyrrole as a capping agent. The magnetic Fe3O4 particles were characterized by several methods, such as SEM, XRD, FTIR, and TGA. The average aspect ratio of Fe3O4 rod-shaped particles was ~2.8. These particles were redispersed in deionised water to form a colloidal solution and showed magnetic properties. This economical synthesis route is scalable, and Fe3O4 particles can be exploited for various applications such as MRI contrast enhancement, biodiseperations, Ni-Fe batteries, and as a catalyst.

  17. Carrier-inside-carrier: polyelectrolyte microcapsules as reservoir for drug-loaded liposomes.

    Science.gov (United States)

    Maniti, Ofelia; Rebaud, Samuel; Sarkis, Joe; Jia, Yi; Zhao, Jie; Marcillat, Olivier; Granjon, Thierry; Blum, Loïc; Li, Junbai; Girard-Egrot, Agnès

    2015-01-01

    Conventional liposomes have a short life-time in blood, unless they are protected by a polymer envelope, most often polyethylene glycol. However, these stabilizing polymers frequently interfere with cellular uptake, impede liposome-membrane fusion and inhibit escape of liposome content from endosomes. To overcome such drawbacks, polymer-based systems as carriers for liposomes are currently developed. Conforming to this approach, we propose a new and convenient method for embedding small size liposomes, 30-100 nm, inside porous calcium carbonate microparticles. These microparticles served as templates for deposition of various polyelectrolytes to form a protective shell. The carbonate particles were then dissolved to yield hollow polyelectrolyte microcapsules. The main advantage of using this method for liposome encapsulation is that carbonate particles can serve as a sacrificial template for deposition of virtually any polyelectrolyte. By carefully choosing the shell composition, bioavailability of the liposomes and of the encapsulated drug can be modulated to respond to biological requirements and to improve drug delivery to the cytoplasm and avoid endosomal escape.

  18. Magnetic alginate microparticles for purification of .alpha.-amylases

    Czech Academy of Sciences Publication Activity Database

    Šafaříková, Miroslava; Roy, I.; Gupta, M. N.; Šafařík, Ivo

    2003-01-01

    Roč. 105, - (2003), s. 255-260 ISSN 0168-1656 R&D Projects: GA MŠk OC 523.80; GA AV ČR IBS6087204 Institutional research plan: CEZ:AV0Z6087904 Keywords : alginate * ferrofluid * amalyses Subject RIV: CE - Biochemistry Impact factor: 2.543, year: 2003

  19. Influence of Magnetic Microparticles Isolation on Adenine Homonucleotides Structure

    Directory of Open Access Journals (Sweden)

    Monika Kremplova

    2014-02-01

    Full Text Available The electroactivity of purine and pyrimidine bases is the most important property of nucleic acids that is very useful for determining oligonucleotides using square wave voltammetry. This study was focused on the electrochemical behavior of adenine-containing oligonucleotides before and after their isolation using paramagnetic particles. Two peaks were detected—peak A related to the reduction of adenine base and another peak B involved in the interactions between individual adenine strands and contributes to the formation of various spatial structures. The influence of the number of adenine bases in the strand in the isolation process using paramagnetic particles was investigated too.

  20. Cell-derived microparticles in the pathogenesis of cardiovascular disease: friend or foe?

    Science.gov (United States)

    Tushuizen, Maarten E; Diamant, Michaela; Sturk, Augueste; Nieuwland, Rienk

    2011-01-01

    Microparticles are ascribed important roles in coagulation, inflammation, and endothelial function. These processes are mandatory to safeguard the integrity of the organism, and their derangements contribute to the development of atherosclerosis and cardiovascular disease. More recently, the presumed solely harmful role of microparticles has been challenged because microparticles may also be involved in the maintenance and preservation of cellular homeostasis and in promoting defense mechanisms. Here, we summarize recent studies revealing these 2 faces of microparticles in cardiovascular disease.

  1. Physical and electrochemical study of cobalt oxide nano- and microparticles

    Energy Technology Data Exchange (ETDEWEB)

    Alburquenque, D. [Dpto. de Química de los Materiales, USACh, Av. L.B.O.‘Higgins 3363, 9170022 Santiago (Chile); Dpto. de Metalurgia, USACh, Av. Ecuador 3469, 9170124, Santiago (Chile); Vargas, E. [Dpto. de Física, USACh and CEDENNA, Av. Ecuador 3493, 9170124 Santiago (Chile); Dpto. de Metalurgia, USACh, Av. Ecuador 3469, 9170124, Santiago (Chile); Denardin, J.C.; Escrig, J. [Dpto. de Física, USACh and CEDENNA, Av. Ecuador 3493, 9170124 Santiago (Chile); Marco, J.F. [Instituto de Química Física “Rocasolano”, CSIC, c/Serrano 119, 28006 Madrid (Spain); Ortiz, J. [Dpto. de Química de los Materiales, USACh, Av. L.B.O.‘Higgins 3363, 9170022 Santiago (Chile); Gautier, J.L., E-mail: juan.gautier@usach.cl [Dpto. de Química de los Materiales, USACh, Av. L.B.O.‘Higgins 3363, 9170022 Santiago (Chile)

    2014-07-01

    Cobalt oxide nanocrystals of size 17–21 nm were synthesized by a simple reaction between cobalt acetate (II) and dodecylamine. On the other hand, micrometric Co{sub 3}O{sub 4} was prepared using the ceramic method. The structural examination of these materials was performed using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM and HRTEM). XRD studies showed that the oxides were pure, well-crystallized, spinel cubic phases with a-cell parameter of 0.8049 nm and 0.8069 nm for the nano and micro-oxide, respectively. The average particle size was 19 nm (nano-oxide) and 1250 μm (micro-oxide). Morphological studies carried out by SEM and TEM analyses have shown the presence of octahedral particles in both cases. Bulk and surface properties investigated by X-ray photoelectron spectroscopy (XPS), point zero charge (pzc), FTIR and cyclic voltammetry indicated that there were no significant differences in the composition on both materials. The magnetic behavior of the samples was determined using a vibrating sample magnetometer. The compounds showed paramagnetic character and no coercivity and remanence in all cases. Galvanostatic measurements of electrodes formed with nanocrystals showed better performance than those built with micrometric particles. - Highlights: • Spinel Co{sub 3}O{sub 4} nanoparticles and microparticles with same structure but with different cell parameters, particle size and surface area were synthesized. • Oxide nanoparticles showed better electrochemical behavior than micrometric ones due to area effect.

  2. MAGNET

    CERN Multimedia

    by B. Curé

    2011-01-01

    The magnet operation was very satisfactory till the technical stop at the end of the year 2010. The field was ramped down on 5th December 2010, following the successful regeneration test of the turbine filters at full field on 3rd December 2010. This will limit in the future the quantity of magnet cycles, as it is no longer necessary to ramp down the magnet for this type of intervention. This is made possible by the use of the spare liquid Helium volume to cool the magnet while turbines 1 and 2 are stopped, leaving only the third turbine in operation. This obviously requires full availability of the operators to supervise the operation, as it is not automated. The cryogenics was stopped on 6th December 2010 and the magnet was left without cooling until 18th January 2011, when the cryoplant operation resumed. The magnet temperature reached 93 K. The maintenance of the vacuum pumping was done immediately after the magnet stop, when the magnet was still at very low temperature. Only the vacuum pumping of the ma...

  3. Liposomes self-assembled from electrosprayed composite microparticles

    International Nuclear Information System (INIS)

    Yu Dengguang; Yang Junhe; Wang Xia; Tian Feng

    2012-01-01

    Composite microparticles, consisting of polyvinylpyrrolidone (PVP), naproxen (NAP) and lecithin (PC), have been successfully prepared using an electrospraying process and exploited as templates to manipulate molecular self-assembly for the synthesis of liposomes in situ. Field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) observations demonstrate that the microparticles have an average diameter of 960 ± 140 nm and a homogeneous structure. X-ray diffraction (XRD) patterns, differential scanning calorimetry (DSC) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) results verify that the building blocks NAP and PC are scattered in the polymer matrix in a molecular way owing to the very fast drying of the electrospraying process and the favorable secondary interactions among the components. FESEM, scanning probe microscope (SPM) and TEM observations demonstrate that the liposomes can be achieved through molecular self-assembly in situ when the microparticles contact water thanks to ‘like prefers like’ and by means of the confinement effect of the microparticles. The liposomes have an encapsulation rate of 91.3%, and 80.7% of the drug in the liposomes can be freed into the dissolution medium in a sustained way and by a diffusion mechanism over a period of 24 h. The developed strategy not only provides a new, facile, and effective method to assemble and organize molecules of multiple components into liposomes with electrosprayed microparticles as templates, but also opens a new avenue for nanofabrication in a step-by-step and controllable way. (paper)

  4. Preparation and characterisation of ethylcellulose microparticles containing propolis

    Directory of Open Access Journals (Sweden)

    G. B. AVANçO

    2009-02-01

    Full Text Available

    Ethylcellulose microparticles containing propolis ethanolic extract (PE were prepared by the emulsification and solvent evaporation method. Three ratios of ethylcellulose to PE dry residue value (DR were tested (1:0.25, 1:4 and 1:10. Moreover, polysorbate 80 was used as emulsifier in the external phase (1.0 or 1.5% w/w. Regular particle morphology without amorphous and/or sticking characteristics was achieved only when an ethylcellulose:DR ratio of 1:0.25 and 1.0% polysorbate 80 were used. Microparticles had a mean diameter of 85.83 µm. The entrapment efficiency for propolis of the microparticles was 62.99 ± 0.52%. These ethylcellulose microparticles containing propolis would be useful for developing propolis aqueous dosage forms without the strong and unpleasant taste, aromatic odour and high ethanol concentration of PE. Keywords: Brazilian propolis; ethylcellulose; emulsification and solvent evaporation; microparticle characterisation; optimisation.

  5. Bioinspired methodology for preparing magnetic responsive chitosan beads to be integrated in a tubular bioreactor for biomedical applications.

    Science.gov (United States)

    Song, Wenlong; Oliveira, Mariana B; Sher, Praveen; Gil, Sara; Nóbrega, J Miguel; Mano, João F

    2013-08-01

    Magnetic responsive chitosan beads were prepared using a methodology inspired by the rolling of water droplets over lotus leaves. Liquid precursors containing chitosan and magnetic microparticles were dispensed in the form of spherical droplets and crosslinked with genipin over synthetic superhydrophobic surfaces. Scanning electronic microscopy, histology and micro-computed tomography were employed to characterize the structure of the prepared composite beads and the inner distribution of the magnetic particles. Cellular metabolic activity tests showed that fibroblasts-like (L929 cell line) can adhere and proliferate on the prepared chitosan beads. We hypothesize that such spherical biomaterials could be integrated in a new concept of tubular bioreactor. The magnetic beads can be immobilized by an external magnetic field at specific positions and may be transported along the bioreactor by the drag of the culture medium flow. The system behavior was also studied through numerical modeling, which allowed to identify the relative importance of the main parameters, and to conclude that the distance between carrier beads plays a major role on their interaction with the culture medium and, consequently, on the overall system performance. In an up-scaled version of this bioreactor, the herein presented system may comprise different chambers in serial or parallel configurations. This constitutes a simple way of preparing magnetic responsive beads combined with a new design of bioreactor, which may find application in biomedicine and biotechnology, including in cell expansion for tissue engineering or for the production of therapeutic proteins to be used in cell therapies.

  6. Bioinspired methodology for preparing magnetic responsive chitosan beads to be integrated in a tubular bioreactor for biomedical applications

    International Nuclear Information System (INIS)

    Song, Wenlong; Oliveira, Mariana B; Sher, Praveen; Gil, Sara; Mano, João F; Nóbrega, J Miguel

    2013-01-01

    Magnetic responsive chitosan beads were prepared using a methodology inspired by the rolling of water droplets over lotus leaves. Liquid precursors containing chitosan and magnetic microparticles were dispensed in the form of spherical droplets and crosslinked with genipin over synthetic superhydrophobic surfaces. Scanning electronic microscopy, histology and micro-computed tomography were employed to characterize the structure of the prepared composite beads and the inner distribution of the magnetic particles. Cellular metabolic activity tests showed that fibroblasts-like (L929 cell line) can adhere and proliferate on the prepared chitosan beads. We hypothesize that such spherical biomaterials could be integrated in a new concept of tubular bioreactor. The magnetic beads can be immobilized by an external magnetic field at specific positions and may be transported along the bioreactor by the drag of the culture medium flow. The system behavior was also studied through numerical modeling, which allowed to identify the relative importance of the main parameters, and to conclude that the distance between carrier beads plays a major role on their interaction with the culture medium and, consequently, on the overall system performance. In an up-scaled version of this bioreactor, the herein presented system may comprise different chambers in serial or parallel configurations. This constitutes a simple way of preparing magnetic responsive beads combined with a new design of bioreactor, which may find application in biomedicine and biotechnology, including in cell expansion for tissue engineering or for the production of therapeutic proteins to be used in cell therapies. (paper)

  7. Microparticles as immune regulators in infectious disease

    Directory of Open Access Journals (Sweden)

    Zheng Lung Ling

    2011-11-01

    Full Text Available Despite their clear relationship to immunology, few existing studies have examined potential role of microparticles (MP in infectious disease. Infection with pathogens usually leads to the expression of a range of inflammatory cytokines and chemokines, as well as significant stress in both infected and uninfected cells. It is thus reasonable to infer from studies to date that infection-associated inflammation also leads to MP production. MP are produced by most of the major cell types in the immune system, and appear to be involved at both the innate and adaptive levels, potentially serving different functions at each level. Thus, MP do not appear to have a universal function; instead their functions are source- or stimulus-dependent, although likely to be primarily either pro- or anti-inflammatory. Importantly, in infectious diseases MP may have the ability to deliver antigen to APC via the biological cargo acquired from their cells of origin. Another potential benefit of MP would be to transfer and/or disseminate phenotype and function to target cells. However, MP may also potentially be manipulated, particularly by intracellular pathogens for survival advantage.

  8. Characterization of spray dried bioadhesive metformin microparticles for oromucosal administration

    DEFF Research Database (Denmark)

    Sander, Camilla; Madsen, Katrine Dragsbæk; Hyrup, Birgitte

    2013-01-01

    delivery systems are considered a promising approach as they facilitate a close contact between the drug and the oral mucosa. In this study, bioadhesive chitosan-based microparticles of metformin hydrochloride were prepared by spray drying aqueous dispersions with different chitosan:metformin ratios...... be prepared and analyzed using the ex vivo retention model. We observed an increase in metformin retention on porcine mucosa with increasing chitosan:metformin ratios, while no effect of increasing the chitosan molecular weight was found. Rheological characterization of feeds for spray drying was performed...... and chitosan grades with increasing molecular weights. A recently developed ex vivo flow retention model with porcine buccal mucosa was used to evaluate the bioadhesive properties of spray dried microparticles. An important outcome of this study was that microparticles with the desired metformin content could...

  9. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    Operation of the magnet has gone quite smoothly during the first half of this year. The magnet has been at 4.5K for the full period since January. There was an unplanned short stop due to the CERN-wide power outage on May 28th, which caused a slow dump of the magnet. Since this occurred just before a planned technical stop of the LHC, during which access in the experimental cavern was authorized, it was decided to leave the magnet OFF until 2nd June, when magnet was ramped up again to 3.8T. The magnet system experienced a fault also resulting in a slow dump on April 14th. This was triggered by a thermostat on a filter choke in the 20kA DC power converter. The threshold of this thermostat is 65°C. However, no variation in the water-cooling flow rate or temperature was observed. Vibration may have been the root cause of the fault. All the thermostats have been checked, together with the cables, connectors and the read out card. The tightening of the inductance fixations has also been checked. More tem...

  10. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet was energised at the beginning of March 2012 at a low current to check all the MSS safety chains. Then the magnet was ramped up to 3.8 T on 6 March 2012. Unfortunately two days later an unintentional switch OFF of the power converter caused a slow dump. This was due to a misunderstanding of the CCC (CERN Control Centre) concerning the procedure to apply for the CMS converter control according to the beam-mode status at that time. Following this event, the third one since 2009, a discussion was initiated to define possible improvement, not only on software and procedures in the CCC, but also to evaluate the possibility to upgrade the CMS hardware to prevent such discharge from occurring because of incorrect procedure implementations. The magnet operation itself was smooth, and no power cuts took place. As a result, the number of magnetic cycles was reduced to the minimum, with only two full magnetic cycles from 0 T to 3.8 T. Nevertheless the magnet suffered four stops of the cryogeni...

  11. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      Following the unexpected magnet stops last August due to sequences of unfortunate events on the services and cryogenics [see CMS internal report], a few more events and initiatives again disrupted the magnet operation. All the magnet parameters stayed at their nominal values during this period without any fault or alarm on the magnet control and safety systems. The magnet was stopped for the September technical stop to allow interventions in the experimental cavern on the detector services. On 1 October, to prepare the transfer of the liquid nitrogen tank on its new location, several control cables had to be removed. One cable was cut mistakenly, causing a digital input card to switch off, resulting in a cold-box (CB) stop. This tank is used for the pre-cooling of the magnet from room temperature down to 80 K, and for this reason it is controlled through the cryogenics control system. Since the connection of the CB was only allowed for a field below 2 T to avoid the risk of triggering a fast d...

  12. Dynamics of magnetic particles in cylindrical Halbach array: implications for magnetic cell separation and drug targeting.

    Science.gov (United States)

    Babinec, Peter; Krafcík, Andrej; Babincová, Melánia; Rosenecker, Joseph

    2010-08-01

    Magnetic nanoparticles for therapy and diagnosis are at the leading edge of the rapidly developing field of bionanotechnology. In this study, we have theoretically studied motion of magnetic nano- as well as micro-particles in the field of cylindrical Halbach array of permanent magnets. Magnetic flux density was modeled as magnetostatic problem by finite element method and particle motion was described using system of ordinary differential equations--Newton law. Computations were done for nanoparticles Nanomag-D with radius 65 nm, which are often used in magnetic drug targeting, as well as microparticles DynaBeads-M280 with radius 1.4 microm, which can be used for magnetic separation. Analyzing snapshots of trajectories of hundred magnetite particles of each size in the water as well as in the air, we have found that optimally designed magnetic circuits of permanent magnets in quadrupolar Halbach array have substantially shorter capture time than simple blocks of permanent magnets commonly used in experiments, therefore, such a Halbach array may be useful as a potential source of magnetic field for magnetic separation and targeting of magnetic nanoparticles as well as microparticles for delivery of drugs, genes, and cells in various biomedical applications.

  13. Protein encapsulation via porous CaCO3 microparticles templating.

    Science.gov (United States)

    Volodkin, Dmitry V; Larionova, Natalia I; Sukhorukov, Gleb B

    2004-01-01

    Porous microparticles of calcium carbonate with an average diameter of 4.75 microm were prepared and used for protein encapsulation in polymer-filled microcapsules by means of electrostatic layer-by-layer assembly (ELbL). Loading of macromolecules in porous CaCO3 particles is affected by their molecular weight due to diffusion-limited permeation inside the particles and also by the affinity to the carbonate surface. Adsorption of various proteins and dextran was examined as a function of pH and was found to be dependent both on the charge of the microparticles and macromolecules. The electrostatic effect was shown to govern this interaction. This paper discusses the factors which can influence the adsorption capacity of proteins. A new way of protein encapsulation in polyelectrolyte microcapsules is proposed exploiting the porous, biocompatible, and decomposable microparticles from CaCO3. It consists of protein adsorption in the pores of the microparticles followed by ELbL of oppositely charged polyelectrolytes and further core dissolution. This resulted in formation of polyelectrolyte-filled capsules with protein incorporated in interpenetrating polyelectrolyte network. The properties of CaCO3 microparticles and capsules prepared were characterized by scanning electron microscopy, microelectrophoresis, and confocal laser scanning microscopy. Lactalbumin was encapsulated by means of the proposed technique yielding a content of 0.6 pg protein per microcapsule. Horseradish peroxidase saves 37% of activity after encapsulation. However, the thermostability of the enzyme was improved by encapsulation. The results demonstrate that porous CaCO3 microparticles can be applied as microtemplates for encapsulation of proteins into polyelectrolyte capsules at neutral pH as an optimal medium for a variety of bioactive material, which can also be encapsulated by the proposed method. Microcapsules filled with encapsulated material may find applications in the field of

  14. Microstructure of dimethylsiloxane based magnetic elastomers

    International Nuclear Information System (INIS)

    Balasoiu, M.; Craus, M.L.; Anitas, E.M.; Bica, I.; Plestil, J.; Kuklin, A.I.

    2009-01-01

    Dimethylsiloxane based elastomers filled with two types of magnetic particles (nano- and micro-sized) were investigated. It was obtained that doping with Fe 3 O 4 nanoparticles and applying of magnetic field during the polymerization process leads to a significant change of the local structure of elastomer. After filling the polymer with Fe 3 O 4 nanoparticles the magnetic elastomer presents a mass fractal structure. The mass fractal dimension is decreasing in the magnetic elastomer polymerized in magnetic field. For the elastomer filled with a large amount of Fe microparticles (75% particle concentration) a texture effect is detected; for the samples polymerized in magnetic field the texture effect is higher. Surface fractal property is obtained for all microparticle concentrations

  15. Development of electrosprayed mucoadhesive chitosan microparticles

    DEFF Research Database (Denmark)

    Moreno, Jorge Alberto S.; Mendes, Ana C.; Stephansen, Karen

    2018-01-01

    The efficacy of chitosan (CS) to be used as drug delivery carrier has previously been reported. However, limited work has been pursued to produce stable and mucoadhesive CS electrosprayed particles for oral drug delivery, which is the aim of this study. Various CS types with different molecular...

  16. Dielectrophoretic Manipulation and Separation of Microparticles Using Microarray Dot Electrodes

    Directory of Open Access Journals (Sweden)

    Bashar Yafouz

    2014-04-01

    Full Text Available This paper introduces a dielectrophoretic system for the manipulation and separation of microparticles. The system is composed of five layers and utilizes microarray dot electrodes. We validated our system by conducting size-dependent manipulation and separation experiments on 1, 5 and 15 μm polystyrene particles. Our findings confirm the capability of the proposed device to rapidly and efficiently manipulate and separate microparticles of various dimensions, utilizing positive and negative dielectrophoresis (DEP effects. Larger size particles were repelled and concentrated in the center of the dot by negative DEP, while the smaller sizes were attracted and collected by the edge of the dot by positive DEP.

  17. Biomimetic Molecular Signaling using DNA Walkers on Microparticles.

    Science.gov (United States)

    Damase, Tulsi Ram; Spencer, Adam; Samuel, Bamidele; Allen, Peter B

    2017-06-22

    We report the release of catalytic DNA walkers from hydrogel microparticles and the detection of those walkers by substrate-coated microparticles. This might be considered a synthetic biology analog of molecular signal release and reception. One type of particles was coated with components of a DNA one-step strand displacement (OSD) reaction to release the walker. A second type of particle was coated with substrate (or "track") for the molecular walker. We distinguish these particle types using fluorescence barcoding: we synthesized and distinguished multiple particle types with multicolor fluorescence microscopy and automated image analysis software. This represents a step toward amplified, multiplex, and microscopically localized detection based on DNA nanotechnology.

  18. Preparation and Characterization of Keratin/Alginate Blend Microparticles

    OpenAIRE

    Srisuwan, Yaowalak; Srihanam, Prasong

    2018-01-01

    The water-in-oil (W/O) emulsification-diffusion method was used for construction of keratin (Ker), alginate (Alg), and Ker/Alg blend microparticles. The Ker, Alg, and Ker/Alg blend solutions were used as the water phase, while ethyl acetate was used as the oil phase. Firstly, different concentrations of Ker solution was used to find suitable content. 1.6% w/v Ker solution was blended with the same concentration of the Alg solution for further microparticle construction. Results from scanning ...

  19. Facile fabrication of siloxane @ poly (methylacrylic acid) core-shell microparticles with different functional groups

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zheng-Bai; Tai, Li; Zhang, Da-Ming; Jiang, Yong, E-mail: yj@seu.edu.cn [Southeast University, School of Chemistry and Chemical Engineering (China)

    2017-02-15

    Siloxane @ poly (methylacrylic acid) core-shell microparticles with functional groups were prepared by a facile hydrolysis-condensation method in this work. Three different silane coupling agents 3-methacryloxypropyltrimethoxysilane (MPS), 3-triethoxysilylpropylamine (APTES), and 3-glycidoxypropyltrimethoxysilane (GPTMS) were added along with tetraethoxysilane (TEOS) into the polymethylacrylic acid (PMAA) microparticle ethanol dispersion to form the Si@PMAA core-shell microparticles with different functional groups. The core-shell structure and the surface special functional groups of the resulting microparticles were measured by transmission electron microscopy and FTIR. The sizes of these core-shell microparticles were about 350–400 nm. The corresponding preparation conditions and mechanism were discussed in detail. This hydrolysis-condensation method also could be used to functionalize other microparticles which contain active groups on the surface. Meanwhile, the Si@PMAA core-shell microparticles with carbon-carbon double bonds and amino groups have further been applied to prepare hydrophobic coatings.

  20. Facile fabrication of siloxane @ poly (methylacrylic acid) core-shell microparticles with different functional groups

    International Nuclear Information System (INIS)

    Zhao, Zheng-Bai; Tai, Li; Zhang, Da-Ming; Jiang, Yong

    2017-01-01

    Siloxane @ poly (methylacrylic acid) core-shell microparticles with functional groups were prepared by a facile hydrolysis-condensation method in this work. Three different silane coupling agents 3-methacryloxypropyltrimethoxysilane (MPS), 3-triethoxysilylpropylamine (APTES), and 3-glycidoxypropyltrimethoxysilane (GPTMS) were added along with tetraethoxysilane (TEOS) into the polymethylacrylic acid (PMAA) microparticle ethanol dispersion to form the Si@PMAA core-shell microparticles with different functional groups. The core-shell structure and the surface special functional groups of the resulting microparticles were measured by transmission electron microscopy and FTIR. The sizes of these core-shell microparticles were about 350–400 nm. The corresponding preparation conditions and mechanism were discussed in detail. This hydrolysis-condensation method also could be used to functionalize other microparticles which contain active groups on the surface. Meanwhile, the Si@PMAA core-shell microparticles with carbon-carbon double bonds and amino groups have further been applied to prepare hydrophobic coatings.

  1. Photochemical half-cells using mixture films of fullerene-ethylenediamine adduct microparticles and polythiophene

    International Nuclear Information System (INIS)

    Akiyama, Tsuyoshi; Oku, Takeo; Matsumura, Satoshi; Matsuoka, Ken-ichi; Yamada, Sunao

    2013-01-01

    In this study, C 60 fullerene–ethylenediamine adduct microparticles were prepared. Mixture films of these microparticles and polythiophene were fabricated on indium–tin-oxide transparent electrodes by spin-coating. Incorporation of C 60 –ethylenediamine microparticles was verified by scanning electron microscopy (SEM) measurements. The coverage values of these microparticles were approximately 3–17%, which were calculated from SEM images of modified electrodes. Fluorescence spectra of modified electrodes indicated that the emission intensity of polythiophene in these mixture films was apparently quenched by these C 60 –ethylenediamine microparticles as compared with a polythiophene film without these microparticles. In the presence of methylviologen, these modified electrodes generated stable photocurrent. The photoexciting species was polythiophene, which was verified by profiles of photocurrent action spectra. The C 60 –ethylenediamine microparticles substantially enhanced the photocurrent signals generated by the polythiophene-modified electrode.

  2. Microparticle content of platelet concentrates is predicted by donor microparticles and is altered by production methods and stress

    DEFF Research Database (Denmark)

    Maurer-Spurej, Elisabeth; Larsen, Rune; Labrie, Audrey

    2016-01-01

    In circulation, shedding of microparticles from a variety of viable cells can be triggered by pathological activation of inflammatory processes, by activation of coagulation or complement systems, or by physical stress. Elevated microparticle content (MPC) in donor blood might therefore indicate...... a clinical condition of the donor which, upon transfusion, might affect the recipient. In blood products, elevated MPC might also represent product stress. Surprisingly, the MPC in blood collected from normal blood donors is highly variable, which raises the question whether donor microparticles are present...... in-vivo and transfer into the final blood component, and how production methods and post-production processing might affect the MPC. We measured MPC using ThromboLUX in (a) platelet-rich plasma (PRP) of 54 apheresis donors and the corresponding apheresis products, (b) 651 apheresis and 646 pooled...

  3. Preparation and anti-tumor efficiency evaluation of doxorubicin-loaded bacterial magnetosomes: magnetic nanoparticles as drug carriers isolated from Magnetospirillum gryphiswaldense.

    Science.gov (United States)

    Sun, Jian-Bo; Duan, Jin-Hong; Dai, Shun-Ling; Ren, Jun; Guo, Lin; Jiang, Wei; Li, Ying

    2008-12-15

    Bacterial magnetosomes (BMs) are commonly used as vehicles for certain enzymes, nucleic acids and antibodies, although they have never been considered drug carriers. To evaluate the clinical potential of BMs extracted from Magnetospirillum gryphiswaldense in cancer therapy, doxorubicin (DOX) was loaded onto the purified BMs at a ratio of 0.87 +/- 0.08 mg/mg using glutaraldehyde. The DOX-coupled BMs (DBMs) and BMs exhibited uniform sizes and morphology evaluated by TEM. The diameters of DBMs and BMs obtained by AFM were 71.02 +/- 6.73 and 34.93 +/- 8.24 nm, respectively. The DBMs released DOX slowly into serum and maintained at least 80% stability following 48 h of incubation. In vitro cytotoxic tests showed that the DBMs were cytotoxic to HL60 and EMT-6 cells, manifested as inhibition of cell proliferation and suppression in c-myc expression, consistent with DOX. These observations depicted in vitro antitumor property of DBMs similar to DOX. The approach of coupling DOX to magnetosomes may have clinical potential in anti-tumor drug delivery.

  4. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet and its sub-systems were stopped at the beginning of the winter shutdown on 8th December 2011. The magnet was left without cooling during the cryogenics maintenance until 17th January 2012, when the cryoplant operation resumed. The magnet temperature reached 93 K. The vacuum pumping was maintained during this period. During this shutdown, the yearly maintenance was performed on the cryogenics, the vacuum pumps, the magnet control and safety systems, and the power converter and discharge lines. Several preventive actions led to the replacement of the electrovalve command coils, and the 20A DC power supplies of the magnet control system. The filters were cleaned on the demineralised water circuits. The oil of the diffusion pumps was changed. On the cryogenics, warm nitrogen at 343 K was circulated in the cold box to regenerate the filters and the heat exchangers. The coalescing filters have been replaced at the inlet of both the turbines and the lubricant trapping unit. The active cha...

  5. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

      The magnet was operated without any problem until the end of the LHC run in February 2013, apart from a CERN-wide power glitch on 10 January 2013 that affected the CMS refrigerator, causing a ramp down to 2 T in order to reconnect the coldbox. Another CERN-wide power glitch on 15 January 2013 didn’t affect the magnet subsystems, the cryoplant or the power converter. At the end of the magnet run, the reconnection of the coldbox at 2.5 T was tested. The process will be updated, in particular the parameters of some PID valve controllers. The helium flow of the current leads was reduced but only for a few seconds. The exercise will be repeated with the revised parameters to validate the automatic reconnection process of the coldbox. During LS1, the water-cooling services will be reduced and many interventions are planned on the electrical services. Therefore, the magnet cryogenics and subsystems will be stopped for several months, and the magnet cannot be kept cold. In order to avoid unc...

  6. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet was successfully operated at the end of the year 2009 despite some technical problems on the cryogenics. The magnet was ramped up to 3.8 T at the end of November until December 16th when the shutdown started. The magnet operation met a few unexpected stops. The field was reduced to 3.5 T for about 5 hours on December 3rd due to a faulty pressure sensor on the helium compressor. The following day the CERN CCC stopped unintentionally the power converters of the LHC and the experiments, triggering a ramp down that was stopped at 2.7 T. The magnet was back at 3.8 T about 6 hours after CCC sent the CERN-wide command. Three days later, a slow dump was triggered due to a stop of the pump feeding the power converter water-cooling circuit, during an intervention on the water-cooling plant done after several disturbances on the electrical distribution network. The magnet was back at 3.8 T in the evening the same day. On December 10th a break occurred in one turbine of the cold box producing the liquid ...

  7. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The CMS magnet has been running steadily and smoothly since the summer, with no detected flaw. The magnet instrumentation is entirely operational and all the parameters are at their nominal values. Three power cuts on the electrical network affected the magnet run in the past five months, with no impact on the data-taking as the accelerator was also affected at the same time. On 22nd June, a thunderstorm caused a power glitch on the service electrical network. The primary water cooling at Point 5 was stopped. Despite a quick restart of the water cooling, the inlet temperature of the demineralised water on the busbar cooling circuit increased by 5 °C, up to 23.3 °C. It was kept below the threshold of 27 °C by switching off other cooling circuits to avoid the trigger of a slow dump of the magnet. The cold box of the cryogenics also stopped. Part of the spare liquid helium volume was used to maintain the cooling of the magnet at 4.5 K. The operators of the cryogenics quickly restarted ...

  8. Nicotine–magnesium aluminum silicate microparticle surface modified with chitosan for mucosal delivery

    Energy Technology Data Exchange (ETDEWEB)

    Kanjanakawinkul, Watchara [Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen 40002 (Thailand); Rades, Thomas [School of Pharmacy, University of Otago, Dunedin 9054 (New Zealand); Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen (Denmark); Puttipipatkhachorn, Satit [Department of Manufacturing Pharmacy, Faculty of Pharmacy, Mahidol University, Bangkok 10400 (Thailand); Pongjanyakul, Thaned, E-mail: thaned@kku.ac.th [Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen 40002 (Thailand)

    2013-04-01

    Magnesium aluminum silicate (MAS), a negatively charged clay, and nicotine (NCT), a basic drug, can interact electrostatically to form microparticles. Chitosan (CS) was used for the surface modification of the microparticles, and a lyophilization method was used to preserve the original particle morphology. The microparticles were characterized in terms of their physicochemical properties, NCT content, mucoadhesive properties, and release and permeation across porcine esophageal mucosa. The results showed that the microparticles formed via electrostatic interaction between MAS and protonated NCT had an irregular shape and that their NCT content increased with increasing NCT ratios in the microparticle preparation solution. High molecular weight CS (800 kDa) adsorbed to the microparticle surface and induced a positive surface charge. CS molecules intercalated into the MAS silicate layers and decreased the crystallinity of the microparticles, leading to an increase in the release rate and diffusion coefficient of NCT from the microparticles. Moreover, the microparticle surface modified with CS was found to have higher NCT permeation fluxes and mucoadhesive properties, which indicated the significant role of CS for NCT mucosal delivery. However, the enhancement of NCT permeation and of mucoadhesive properties depended on the molecular weight and concentration of CS. These findings suggest that NCT-MAS microparticle surface modified with CS represents a promising mucosal delivery system for NCT. Highlights: ► Nicotine–magnesium aluminum silicate microparticles were prepared using electrostatic interaction. ► Lyophilization was used for drying and maintaining an original morphology of the microparticles. ► Chitosan (CS) was used for surface modification of the microparticles at acidic pH. ► Surface modification using CS caused an increase in release and permeation of nicotine. ► Microparticle surface-modified with CS presented better mucoadhesive properties.

  9. Nicotine–magnesium aluminum silicate microparticle surface modified with chitosan for mucosal delivery

    International Nuclear Information System (INIS)

    Kanjanakawinkul, Watchara; Rades, Thomas; Puttipipatkhachorn, Satit; Pongjanyakul, Thaned

    2013-01-01

    Magnesium aluminum silicate (MAS), a negatively charged clay, and nicotine (NCT), a basic drug, can interact electrostatically to form microparticles. Chitosan (CS) was used for the surface modification of the microparticles, and a lyophilization method was used to preserve the original particle morphology. The microparticles were characterized in terms of their physicochemical properties, NCT content, mucoadhesive properties, and release and permeation across porcine esophageal mucosa. The results showed that the microparticles formed via electrostatic interaction between MAS and protonated NCT had an irregular shape and that their NCT content increased with increasing NCT ratios in the microparticle preparation solution. High molecular weight CS (800 kDa) adsorbed to the microparticle surface and induced a positive surface charge. CS molecules intercalated into the MAS silicate layers and decreased the crystallinity of the microparticles, leading to an increase in the release rate and diffusion coefficient of NCT from the microparticles. Moreover, the microparticle surface modified with CS was found to have higher NCT permeation fluxes and mucoadhesive properties, which indicated the significant role of CS for NCT mucosal delivery. However, the enhancement of NCT permeation and of mucoadhesive properties depended on the molecular weight and concentration of CS. These findings suggest that NCT-MAS microparticle surface modified with CS represents a promising mucosal delivery system for NCT. Highlights: ► Nicotine–magnesium aluminum silicate microparticles were prepared using electrostatic interaction. ► Lyophilization was used for drying and maintaining an original morphology of the microparticles. ► Chitosan (CS) was used for surface modification of the microparticles at acidic pH. ► Surface modification using CS caused an increase in release and permeation of nicotine. ► Microparticle surface-modified with CS presented better mucoadhesive properties

  10. Effect of interlayer tunneling on the electronic structure of bilayer cuprates and quantum phase transitions in carrier concentration and high magnetic field

    International Nuclear Information System (INIS)

    Ovchinnikov, S. G.; Makarov, I. A.; Shneyder, E. I.

    2011-01-01

    We present a theoretical study of the electronic structure of bilayer HTSC cuprates and its evolution under doping and in a high magnetic field. Analysis is based on the t-t′-t″-J* model in the generalized Hartree-Fock approximation. Possibility of tunneling between CuO2 layers is taken into account in the form of a nonzero integral of hopping between the orbitals of adjacent planes and is included in the scheme of the cluster form of perturbation theory. The main effect of the coupling between two CuO 2 layers in a unit cell is the bilayer splitting manifested in the presence of antibonding and bonding bands formed by a combination of identical bands of the layers themselves. A change in the doping level induces reconstruction of the band structure and the Fermi surface, which gives rise to a number of quantum phase transitions. A high external magnetic field leads to a fundamentally different form of electronic structure. Quantum phase transitions in the field are observed not only under doping, but also upon a variation of the field magnitude. Because of tunneling between the layers, quantum transitions are also split; as a result, a more complex sequence of the Lifshitz transitions than in single-layer structures is observed.

  11. Dextran-based hydrogel containing chitosan microparticles loaded with growth factors to be used in wound healing

    International Nuclear Information System (INIS)

    Ribeiro, M.P.; Morgado, P.I.; Miguel, S.P.; Coutinho, P.; Correia, I.J.

    2013-01-01

    Skin injuries are traumatic events, which are seldom accompanied by complete structural and functional restoration of the original tissue. Different strategies have been developed in order to make the wound healing process faster and less painful. In the present study in vitro and in vivo assays were carried out to evaluate the applicability of a dextran hydrogel loaded with chitosan microparticles containing epidermal and vascular endothelial growth factors, for the improvement of the wound healing process. The carriers' morphology was characterized by scanning electron microscopy. Their cytotoxicity profile and degradation by-products were evaluated through in vitro assays. In vivo experiments were also performed to evaluate their applicability for the treatment of skin burns. The wound healing process was monitored through macroscopic and histological analysis. The macroscopic analysis showed that the period for wound healing occurs in animals treated with microparticle loaded hydrogels containing growth factors that were considerably smaller than that of control groups. Moreover, the histological analysis revealed the absence of reactive or granulomatous inflammatory reaction in skin lesions. The results obtained both in vitro and in vivo disclosed that these systems and its degradation by-products are biocompatible, contributed to the re-establishment of skin architecture and can be used in a near future for the controlled delivery of other bioactive agents used in regenerative medicine. - Highlights: • Evaluation of a hydrogel loaded with microparticles containing growth factors for wound healing • In vitro and in vivo assays were performed to characterize the properties of the skin substitute. • The monitoring of the wound healing process was done by macroscopic and histological analysis

  12. Dextran-based hydrogel containing chitosan microparticles loaded with growth factors to be used in wound healing

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, M.P. [CICS-UBI, Health Sciences Research Center, Faculty of Health Sciences, University of Beira Interior, Covilhã (Portugal); UDI-IPG, Research Unit for Inland Development, Polytechnic Institute of Guarda, Guarda (Portugal); Morgado, P.I.; Miguel, S.P. [CICS-UBI, Health Sciences Research Center, Faculty of Health Sciences, University of Beira Interior, Covilhã (Portugal); Coutinho, P. [CICS-UBI, Health Sciences Research Center, Faculty of Health Sciences, University of Beira Interior, Covilhã (Portugal); UDI-IPG, Research Unit for Inland Development, Polytechnic Institute of Guarda, Guarda (Portugal); Correia, I.J., E-mail: icorreia@ubi.pt [CICS-UBI, Health Sciences Research Center, Faculty of Health Sciences, University of Beira Interior, Covilhã (Portugal)

    2013-07-01

    Skin injuries are traumatic events, which are seldom accompanied by complete structural and functional restoration of the original tissue. Different strategies have been developed in order to make the wound healing process faster and less painful. In the present study in vitro and in vivo assays were carried out to evaluate the applicability of a dextran hydrogel loaded with chitosan microparticles containing epidermal and vascular endothelial growth factors, for the improvement of the wound healing process. The carriers' morphology was characterized by scanning electron microscopy. Their cytotoxicity profile and degradation by-products were evaluated through in vitro assays. In vivo experiments were also performed to evaluate their applicability for the treatment of skin burns. The wound healing process was monitored through macroscopic and histological analysis. The macroscopic analysis showed that the period for wound healing occurs in animals treated with microparticle loaded hydrogels containing growth factors that were considerably smaller than that of control groups. Moreover, the histological analysis revealed the absence of reactive or granulomatous inflammatory reaction in skin lesions. The results obtained both in vitro and in vivo disclosed that these systems and its degradation by-products are biocompatible, contributed to the re-establishment of skin architecture and can be used in a near future for the controlled delivery of other bioactive agents used in regenerative medicine. - Highlights: • Evaluation of a hydrogel loaded with microparticles containing growth factors for wound healing • In vitro and in vivo assays were performed to characterize the properties of the skin substitute. • The monitoring of the wound healing process was done by macroscopic and histological analysis.

  13. Albumin microparticles as the carriers for allopurinol and applicable for the treatment of ischemic stroke

    Science.gov (United States)

    Aganyants, Hovsep Alexandr; Nikohosyan, Gayane; Danielyan, Kristine Edgar

    2016-11-01

    Albumin nanoparticles are already used for the treatment of the cancer. In our current work, it is presented the technique for the preparation of small-size 1- to 5-micron particles coated with the allopurinol. We propose that this combination of the compounds might be useful for the ischemic stroke treatment as the agent preventing formation of the brain edema, reactive oxygen species, and initiation of cells regeneration. Glutaraldehyde was used for the polymerization of albumin. Determination of the particle size was performed by the light as well as phase contrast microscopies and analyzed by Pixcavator 6.0 and Image Tool programs. Modification and establishment of iodine-based method served as the base for quantification of bound with the particles and free allopurinol. As a consequence of the experiments, the best formulation of glutaraldehyde ratio and albumin quantity as well as conditions for the formation of the smallest sized spheroid-shaped particles were found for the further in vivo application.

  14. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The magnet ran smoothly in the last few months until a fast dump occurred on 9th May 2011. Fortunately, this occurred in the afternoon of the first day of the technical stop. The fast dump was due to a valve position controller that caused the sudden closure of a valve. This valve is used to regulate the helium flow on one of the two current leads, which electrically connects the coil at 4.5 K to the busbars at room temperature. With no helium flow on the lead, the voltage drop and the temperatures across the leads increase up to the defined thresholds, triggering a fast dump through the Magnet Safety System (MSS). The automatic reaction triggered by the MSS worked properly. The helium release was limited as the pressure rise was just at the limit of the safety valve opening pressure. The average temperature of the magnet reached 72 K. It took four days to recover the temperature and refill the helium volumes. The faulty valve controller was replaced by a spare one before the magnet ramp-up resumed....

  15. Distinct proteome pathology of circulating microparticles in systemic lupus erythematosus

    DEFF Research Database (Denmark)

    Østergaard, Ole; Nielsen, Christoffer Tandrup; Tanassi, Julia Tanas

    2017-01-01

    BACKGROUND: The pathogenesis of systemic lupus erythematosus (SLE) is poorly understood but has been linked to defective clearance of subcellular particulate material from the circulation. This study investigates the origin, formation, and specificity of circulating microparticles (MPs) in patien...... generation of MPs may partake in the pathology of SLE and that new diagnostic, monitoring, and treatment strategies targeting these processes may be advantageous....

  16. Electroless or autocatalytic coating of microparticles for laser fusion targets

    International Nuclear Information System (INIS)

    Mayer, A.; Catlett, D.S.

    1977-04-01

    Use of a novel device for applying uniform metallic coatings to spherical microparticles is described. The apparatus deposits electroless metal coatings on hollow, thin-walled metal or sensitized nonmetallic micromandrels. The apparatus and process were developed for fabrication of microsphere pressure vessels for use as targets in laser-initiated fusion research

  17. Electrolytic coating of microparticles for laser fusion targets

    International Nuclear Information System (INIS)

    Mayer, A.; Catlett, D.S.

    1977-04-01

    An electroplating apparatus for applying uniform metallic coatings that have excellent surface finishes to discrete microparticles is described. The device is used to electrodeposit metals onto thin-walled metal, metallized glass, or plastic mandrels. The apparatus and process were developed for fabrication of microsphere pressure vessels to be used as targets in laser fusion research

  18. Manipulation of microparticles and red blood cells using ...

    Indian Academy of Sciences (India)

    2014-02-13

    Feb 13, 2014 ... Abstract. We report the development of an optoelectronic tweezers set-up which works by light- induced dielectrophoresis mechanism to manipulate microparticles. We used thermal evaporation technique for coating the organic polymer, titanium oxide phthalocyanine (TiOPc), as a photo- conductive layer ...

  19. The effects of buserelin microparticles on ovarian function in healthy ...

    African Journals Online (AJOL)

    The effects of buserelin microparticles on ovarian function in healthy women. ... A single-blind, randomised, parallel-group design was used to investigate the ... to at least 8 nmoVI (a sign of ovulation) and oestradiol concentrations increased to ...

  20. Controlled electrosprayed formation of non-spherical microparticles

    Science.gov (United States)

    Jeyhani, Morteza; Mak, Sze Yi; Sammut, Stephen; Shum, Ho Cheung; Hwang, Dae Kun; Tsai, Scott S. H.

    2017-11-01

    Fabrication of biocompatible microparticles, such as alginate particles, with the possibility of controlling the particles' morphology in a high-throughput manner, is essential for pharmaceutical and cosmetic industries. Even though the shape of alginate particles has been shown to be an important parameter in controlling drug delivery, there are very limited manufacturing methods to produce non-spherical alginate microparticles in a high-throughput fashion. Here, we present a system that generates non-spherical biocompatible alginate microparticles with a tunable size and shape, and at high-throughput, using an electrospray technique. Alginate solution, which is a highly biocompatible material, is flown through a needle using a constant flow rate syringe pump. The alginate phase is connected to a high-voltage power supply to charge it positively. There is a metallic ring underneath the needle that is charged negatively. The applied voltage creates an electric field that forces the dispensing droplets to pass through the metallic ring toward the collection bath. During this migration, droplets break up to smaller droplets to dissipate their energy. When the droplets reach the calcium chloride bath, polymerization happens and solidifies the droplets. We study the effects of changing the distance from the needle to the bath, and the concentration of calcium chloride in the bath, to control the size and the shape of the resulting microparticles.

  1. Inhibition of microparticle release triggers endothelial cell apoptosis and detachment

    NARCIS (Netherlands)

    Abid Hussein, Mohammed N.; Böing, Anita N.; Sturk, Augueste; Hau, Chi M.; Nieuwland, Rienk

    2007-01-01

    Endothelial cell cultures contain caspase 3-containing microparticles (EMP), which are reported to form during or after cell detachment. We hypothesize that also adherent endothelial cells release EMP, thus protecting these cells from caspase 3 accumulation, detachment and apoptosis. Human umbilical

  2. Ultrasound-induced acoustophoretic motion of microparticles in three dimensions

    DEFF Research Database (Denmark)

    Muller, Peter Barkholt; Rossi, M.; Marín, Á. G.

    2013-01-01

    We derive analytical expressions for the three-dimensional (3D) acoustophoretic motion of spherical microparticles in rectangular microchannels. The motion is generated by the acoustic radiation force and the acoustic streaming-induced drag force. In contrast to the classical theory of Rayleigh...

  3. Non-paraxial beam to push and pull microparticles

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Qiu, C.-W.

    2011-01-01

    We discuss a feasibility of the pulling (backward) force acting on a spherical microparticle in a non-paraxial Bessel beam. The effect can be explained by the strong interaction of particle's multipoles or by the conservation of momentum in the system “photons-particle.” It is remarkable that the...

  4. Development of a microparticle-based dry powder inhalation formulation of ciprofloxacin hydrochloride applying the quality by design approach

    Directory of Open Access Journals (Sweden)

    Karimi K

    2016-10-01

    Full Text Available Keyhaneh Karimi, Edina Pallagi, Piroska Szabó-Révész, Ildikó Csóka, Rita Ambrus Faculty of Pharmacy, Institute of Pharmaceutical Technology and Regulatory Affairs, University of Szeged, Szeged, Hungary Abstract: Pulmonary drug delivery of ciprofloxacin hydrochloride offers effective local antibacterial activity and convenience of easy application. Spray drying is a trustworthy technique for the production of ciprofloxacin hydrochloride microparticles. Quality by design (QbD, an up-to-date regulatory-based quality management method, was used to predict the final quality of the product. According to the QbD-based theoretical preliminary parameter ranking and priority classification, dry powder inhalation formulation tests were successfully performed in practice. When focusing on the critical parameters, the practical development was more effective and was in correlation with our previous findings. Spray drying produced spherical microparticles. The dry powder formulations prepared were examined by particle size analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray powder diffraction, differential scanning calorimetry, and in vitro drug release and aerodynamic particle size analyses were also performed. These formulations showed an appropriate particle size ranging between 2 and 4 µm and displayed an enhanced aerosol performance with fine particle fraction up to 80%. Keywords: antibiotic, carrier-free formulation, quality by design, aerodynamic evaluation, dry powder for inhalation

  5. Characterization and taste masking evaluation of microparticles with cetirizine dihydrochloride and methacrylate-based copolymer obtained by spray drying

    Directory of Open Access Journals (Sweden)

    Amelian Aleksandra

    2017-03-01

    Full Text Available Taste of a pharmaceutical formulation is an important parameter for the effectiveness of pharmacotherapy. Cetirizine dihydrochloride (CET is a second-generation antihistamine that is commonly administered in allergy treatment. CET is characterized by extremely bitter taste and it is a great challenge to successfully mask its taste; therefore the goal of this work was to formulate and characterize the microparticles obtained by the spray drying method with CET and poly(butyl methacrylate-co-(2-dimethylaminoethyl methacrylate-co-methyl methacrylate 1:2:1 copolymer (Eudragit E PO as a barrier coating. Assessment of taste masking by the electronic tongue has revealed that designed formulations created an effective taste masking barrier. Taste masking effect was also confirmed by the in vivo model and the in vitro release profile of CET. Obtained data have shown that microparticles with a drug/polymer ratio (0.5:1 are promising CET carriers with efficient taste masking potential and might be further used in designing orodispersible dosage forms with CET.

  6. Assessing the biodegradability of microparticles disposed down the drain.

    Science.gov (United States)

    McDonough, Kathleen; Itrich, Nina; Casteel, Kenneth; Menzies, Jennifer; Williams, Tom; Krivos, Kady; Price, Jason

    2017-05-01

    Microparticles made from naturally occurring materials or biodegradable plastics such as poly(3-hydroxy butyrate)-co-(3-hydroxy valerate), PHBV, are being evaluated as alternatives to microplastics in personal care product applications but limited data is available on their ultimate biodegradability (mineralization) in down the drain environmental compartments. An OECD 301B Ready Biodegradation Test was used to quantify ultimate biodegradability of microparticles made of PHBV foam, jojoba wax, beeswax, rice bran wax, stearyl stearate, blueberry seeds and walnut shells. PHBV polymer was ready biodegradable reaching 65.4 ± 4.1% evolved CO 2 in 5 d and 90.5 ± 3.1% evolved CO 2 in 80 d. PHBV foam microparticles (125-500 μm) were mineralized extensively with >66% CO 2 evolution in 28 d and >82% CO 2 evolution in 80 d. PHBV foam microparticles were mineralized at a similar rate and extent as microparticles made of jojoba wax, beeswax, rice bran wax, and stearyl stearate which reached 84.8  ± 4.8, 84.9  ± 2.2, 82.7  ± 4.7, and 86.4 ± 3.2% CO 2 evolution respectively in 80 d. Blueberry seeds and walnut shells mineralized more slowly only reaching 39.3  ± 6.9 and 5.1 ± 2.8% CO 2 evolution in 80 d respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Formation of monodisperse mesoporous silica microparticles via spray-drying.

    Science.gov (United States)

    Waldron, Kathryn; Wu, Winston Duo; Wu, Zhangxiong; Liu, Wenjie; Selomulya, Cordelia; Zhao, Dongyuan; Chen, Xiao Dong

    2014-03-15

    In this work, a protocol to synthesize monodisperse mesoporous silica microparticles via a unique microfluidic jet spray-drying route is reported for the first time. The microparticles demonstrated highly ordered hexagonal mesostructures with surface areas ranging from ~900 up to 1500 m(2)/g and pore volumes from ~0.6 to 0.8 cm(3)/g. The particle size could be easily controlled from ~50 to 100 μm from the same diameter nozzle via changing the initial solute content, or changing the drying temperature. The ratio of the surfactant (CTAB) and silica (TEOS), and the amount of water in the precursor were found to affect the degree of ordering of mesopores by promoting either the self-assembly of the surfactant-silica micelles or the condensation of the silica as two competing processes in evaporation induced self-assembly. The drying rate and the curvature of particles also affected the self-assembly of the mesostructure. The particle mesostructure is not influenced by the inlet drying temperature in the range of 92-160 °C, with even a relatively low temperature of 92 °C producing highly ordered mesoporous microparticles. The spray-drying derived mesoporous silica microparticles, while of larger sizes and more rapidly synthesized, showed a comparable performance with the conventional mesoporous silica MCM-41 in controlled release of a dye, Rhodamine B, indicating that these spray dried microparticles could be used for the immobilisation and controlled release of small molecules. Copyright © 2013 Elsevier Inc. All rights reserved.

  8. IGF-1 release kinetics from chitosan microparticles fabricated using environmentally benign conditions

    Energy Technology Data Exchange (ETDEWEB)

    Mantripragada, Venkata P. [Biomedical Engineering Program, The University of Toledo, Toledo, OH 43614-5807 (United States); Jayasuriya, Ambalangodage C., E-mail: a.jayasuriya@utoledo.edu [Biomedical Engineering Program, The University of Toledo, Toledo, OH 43614-5807 (United States); Department of Orthopaedic Surgery, The University of Toledo, Toledo, OH 43614-5807 (United States)

    2014-09-01

    The main objective of this study is to maximize growth factor encapsulation efficiency into microparticles. The novelty of this study is to maximize the encapsulated growth factors into microparticles by minimizing the use of organic solvents and using relatively low temperatures. The microparticles were fabricated using chitosan biopolymer as a base polymer and cross-linked with tripolyphosphate (TPP). Insulin like-growth factor-1 (IGF-1) was encapsulated into microparticles to study release kinetics and bioactivity. In order to authenticate the harms of using organic solvents like hexane and acetone during microparticle preparation, IGF-1 encapsulated microparticles prepared by the emulsification and coacervation methods were compared. The microparticles fabricated by emulsification method have shown a significant decrease (p < 0.05) in IGF-1 encapsulation efficiency, and cumulative release during the two-week period. The biocompatibility of chitosan microparticles and the bioactivity of the released IGF-1 were determined in vitro by live/dead viability assay. The mineralization data observed with von Kossa assay, was supported by mRNA expression levels of osterix and runx2, which are transcription factors necessary for osteoblasts differentiation. Real time RT-PCR data showed an increased expression of runx2 and a decreased expression of osterix over time, indicating differentiating osteoblasts. Chitosan microparticles prepared in optimum environmental conditions are a promising controlled delivery system for cells to attach, proliferate, differentiate and mineralize, thereby acting as a suitable bone repairing material. - Highlights: • Coacervation chitosan microparticles were biocompatible and biodegradable. • IGF-1 encapsulation efficiency increased with coacervation chitosan microparticles. • Coacervation chitosan microparticles support osteoblast attachment and differentiation. • Coacervation chitosan microparticles support osteoblast mineralization.

  9. IGF-1 release kinetics from chitosan microparticles fabricated using environmentally benign conditions

    International Nuclear Information System (INIS)

    Mantripragada, Venkata P.; Jayasuriya, Ambalangodage C.

    2014-01-01

    The main objective of this study is to maximize growth factor encapsulation efficiency into microparticles. The novelty of this study is to maximize the encapsulated growth factors into microparticles by minimizing the use of organic solvents and using relatively low temperatures. The microparticles were fabricated using chitosan biopolymer as a base polymer and cross-linked with tripolyphosphate (TPP). Insulin like-growth factor-1 (IGF-1) was encapsulated into microparticles to study release kinetics and bioactivity. In order to authenticate the harms of using organic solvents like hexane and acetone during microparticle preparation, IGF-1 encapsulated microparticles prepared by the emulsification and coacervation methods were compared. The microparticles fabricated by emulsification method have shown a significant decrease (p < 0.05) in IGF-1 encapsulation efficiency, and cumulative release during the two-week period. The biocompatibility of chitosan microparticles and the bioactivity of the released IGF-1 were determined in vitro by live/dead viability assay. The mineralization data observed with von Kossa assay, was supported by mRNA expression levels of osterix and runx2, which are transcription factors necessary for osteoblasts differentiation. Real time RT-PCR data showed an increased expression of runx2 and a decreased expression of osterix over time, indicating differentiating osteoblasts. Chitosan microparticles prepared in optimum environmental conditions are a promising controlled delivery system for cells to attach, proliferate, differentiate and mineralize, thereby acting as a suitable bone repairing material. - Highlights: • Coacervation chitosan microparticles were biocompatible and biodegradable. • IGF-1 encapsulation efficiency increased with coacervation chitosan microparticles. • Coacervation chitosan microparticles support osteoblast attachment and differentiation. • Coacervation chitosan microparticles support osteoblast mineralization

  10. Composite magnetorheological elastomers as dielectrics for plane capacitors: Effects of magnetic field intensity

    Directory of Open Access Journals (Sweden)

    Maria Balasoiu

    Full Text Available The fabrication of composite magnetorheological elastomers (MRECs based on silicone rubber, carbonyl iron microparticles (10% vol. and polyurethane elastomer doped with 0%, 10% and 20% volume concentration TiO2 microparticles is presented. The obtained MRECs have the shape of thin foils and are used as dielectric materials for manufacturing plane capacitors. Using the plane capacitor method and expression of capacitance as a function of magnetic field intensity, combined with linear elasticity theory, the static magnetoelastic model of the composite is obtained and analyzed. Keywords: Magnetorheological elastomer, TiO2 microparticles, Silicone rubber, Carbonyl iron, Plane capacitor, Magnetoelasticity

  11. Imaging ballistic carrier trajectories in graphene using scanning gate microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Morikawa, Sei; Masubuchi, Satoru [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Dou, Ziwei; Wang, Shu-Wei; Smith, Charles G.; Connolly, Malcolm R., E-mail: mrc61@cam.ac.uk [Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB3 0HE (United Kingdom); Watanabe, Kenji; Taniguchi, Takashi [National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); Machida, Tomoki, E-mail: tmachida@iis.u-tokyo.ac.jp [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Institute for Nano Quantum Information Electronics, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan)

    2015-12-14

    We use scanning gate microscopy to map out the trajectories of ballistic carriers in high-mobility graphene encapsulated by hexagonal boron nitride and subject to a weak magnetic field. We employ a magnetic focusing geometry to image carriers that emerge ballistically from an injector, follow a cyclotron path due to the Lorentz force from an applied magnetic field, and land on an adjacent collector probe. The local electric field generated by the scanning tip in the vicinity of the carriers deflects their trajectories, modifying the proportion of carriers focused into the collector. By measuring the voltage at the collector while scanning the tip, we are able to obtain images with arcs that are consistent with the expected cyclotron motion. We also demonstrate that the tip can be used to redirect misaligned carriers back to the collector.

  12. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet worked very well at 3.8 T as expected, despite a technical issue that manifested twice in the cryogenics since June. All the other magnet sub-systems worked without flaw. The issue in the cryogenics was with the cold box: it could be observed that the cold box was getting progressively blocked, due to some residual humidity and air accumulating in the first thermal exchanger and in the adsorber at 65 K. This was later confirmed by the analysis during the regeneration phases. An increase in the temperature difference between the helium inlet and outlet across the heat exchanger and a pressure drop increase on the filter of the adsorber were observed. The consequence was a reduction of the helium flow, first compensated by the automatic opening of the regulation valves. But once they were fully opened, the flow and refrigeration power reduced as a consequence. In such a situation, the liquid helium level in the helium Dewar decreased, eventually causing a ramp down of the magnet current and a field...

  13. MAGNET

    CERN Multimedia

    B. Curé

    MAGNET During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bough...

  14. MAGNET

    CERN Multimedia

    Benoit Curé.

    The magnet operation restarted end of June this year. Quick routine checks of the magnet sub-systems were performed at low current before starting the ramps up to higher field. It appeared clearly that the end of the field ramp down to zero was too long to be compatible with the detector commissioning and operations plans. It was decided to perform an upgrade to keep the ramp down from 3.8T to zero within 4 hours. On July 10th, when a field of 1.5T was reached, small movements were observed in the forward region support table and it was decided to fix this problem before going to higher field. At the end of July the ramps could be resumed. On July 28th, the field was at 3.8T and the summer CRAFT exercise could start. This run in August went smoothly until a general CERN wide power cut took place on August 3rd, due to an insulation fault on the high voltage network outside point 5. It affected the magnet powering electrical circuit, as it caused the opening of the main circuit breakers, resulting in a fast du...

  15. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

    The magnet is fully stopped and at room temperature. The maintenance works and consolidation activities on the magnet sub-systems are progressing. To consolidate the cryogenic installation, two redundant helium compressors will be installed as ‘hot spares’, to avoid the risk of a magnet downtime in case of a major failure of a compressor unit during operation. The screw compressors, their motors, the mechanical couplings and the concrete blocks are already available and stored at P5. The metallic structure used to access the existing compressors in SH5 will be modified to allow the installation of the two redundant ones. The plan is to finish the installation and commissioning of the hot spare compressors before the summer 2014. In the meantime, a bypass on the high-pressure helium piping will be installed for the connection of a helium drier unit later during the Long Shutdown 1, keeping this installation out of the schedule critical path. A proposal is now being prepared for the con...

  16. Magnetic movement of biological fluid droplets

    International Nuclear Information System (INIS)

    Garcia, Antonio A.; Egatz-Gomez, Ana; Lindsay, Solitaire A.; Dominguez-Garcia, P.; Melle, Sonia; Marquez, Manuel; Rubio, Miguel A.; Picraux, S.T.; Yang, Dongqing; Aella, P.; Hayes, Mark A.; Gust, Devens; Loyprasert, Suchera; Vazquez-Alvarez, Terannie; Wang, Joseph

    2007-01-01

    Magnetic fields can be used to control the movement of aqueous drops on non-patterned, silicon nanowire superhydrophobic surfaces. Drops of aqueous and biological fluids are controlled by introducing magnetizable carbonyl iron microparticles into the liquid. Key elements of operations such as movement, coalescence, and splitting of water and biological fluid drops, as well as electrochemical measurement of an analyte are demonstrated. Superhydrophobic surfaces were prepared using vapor-liquid-solid (VLS) growth systems followed by coating with a perfluorinated hydrocarbon molecule. Drops were made from aqueous and biological fluid suspensions with magnetizable microparticle concentrations ranging from 0.1 to 10 wt%

  17. Acrylic microspheres in vivo. X. Elimination of circulating cells by active targeting using specific monoclonal antibodies bound to microparticles

    International Nuclear Information System (INIS)

    Laakso, T.; Andersson, J.; Artursson, P.; Edman, P.; Sjoeholm, I.

    1986-01-01

    The elimination from the blood of 51 Cr-labelled mouse erythrocytes modified with trinitrophenyl (TNP) groups was followed in mice. After 24 hours, when a stable concentration of the labelled erythrocytes has been attained, monoclonal anti-TNP-antibodies were given intravenously, either in free, soluble form, or bound to microparticles containing immobilized protein A. The anti-TNP-antibodies induced a rapid elimination of the TNP- and 51 Cr-labelled erythrocytes. Over the 8-hours time period studied, the elimination rate was significantly faster when the antibodies were administered bound to the particles. After the elimination of the target cells, the radioactivity was found in the liver, spleen and bone marrow. These results and relevant control experiments indicate that a solid carrier (1) can be directed to a specific target cell with a specific antibody and (2) can induce a rapid elimination of the target cell from the circulation. 31 references, 1 figure, 2 tables

  18. Diagnostics of the influence of levitating microparticles on the radiofrequency argon plasma

    International Nuclear Information System (INIS)

    Pustylnik, Mikhail Y.; Mitic, Slobodan; Klumov, Boris A.; Morfill, Gregor E.

    2010-01-01

    The effect of a levitating cloud of microparticles on the parameters of a radiofrequency (RF) plasma has been studied by means of two experimental techniques. Axial distributions of 1 s excited states of argon were measured by a self-absorption method. A correction of a standard self-absorption method for the extinction of the light by the levitating microparticles is proposed. In addition the electron temperature was estimated using the optical emission spectroscopy. Measurements at the same discharge conditions in a microparticle-free discharge and discharge, containing a cloud of levitating microparticles, revealed the non-local influence of the microparticle cloud on the discharge plasma. The most probable cause of this influence is the disturbance of the ionization balance by the levitating microparticles.

  19. MAGNET

    CERN Multimedia

    Benoit Curé

    The magnet subsystems resumed operation early this spring. The vacuum pumping was restarted mid March, and the cryogenic power plant was restarted on March 30th. Three and a half weeks later, the magnet was at 4.5 K. The vacuum pumping system is performing well. One of the newly installed vacuum gauges had to be replaced at the end of the cool-down phase, as the values indicated were not coherent with the other pressure measurements. The correction had to be implemented quickly to be sure no helium leak could be at the origin of this anomaly. The pressure measurements have been stable and coherent since the change. The cryogenics worked well, and the cool-down went quite smoothly, without any particular difficulty. The automated start of the turbines had to be fine-tuned to get a smooth transition, as it was observed that the cooling power delivered by the turbines was slightly higher than needed, causing the cold box to stop automatically. This had no consequence as the cold box safety system acts to keep ...

  20. MAGNET

    CERN Multimedia

    B. Curé

    During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bought. Th...

  1. DNA-tagged Microparticles for Tracing Water Flows and Travel Times in Natural Systems: The First results from Controlled Laboratory Experiments

    Science.gov (United States)

    Bogaard, T.; Bandyopadhyay, S.; Foppen, J. W.

    2017-12-01

    Societal demand for water safety is continuously increasing, being it resilient against flood/droughts, clean water for ecosystems, recreation or safe drinking water. Robust methods to measure temporal and spatial patterns of water and contaminant pathways are still lacking. Our research project aims to develop and apply (1) innovative, robust, and environmental-friendly silica-protected iron oxide micro-particles tagged with artificial DNA to trace contaminant movement and travel times of water in natural systems and (2) an innovative coupled model approach to capture dynamics in hydrological pathways and their effects on water quality. The exceptional property of DNA-tagging is the infinite number of unique tracers that can be produced and their detectability at extreme low concentrations. The advantage of the iron-core of the particle is the magnetic harvesting of the particles from water-samples. Such tracers are thought to give the water sector a unique tool for in-situ mapping of transport of contaminants and pathogenic microorganisms in water systems. However, the characteristics of the particle like magnetic property of the iron-core and surface potential of the silica layer, are of key importance for the behaviour of the particle in surface water and in soils. Furthermore, the application of such micro-particles requires strict protocols for the experiment, sampling and laboratory handling which are currently not available. We used two different types of silica-protected DNA-tagged micro-particles. We performed batch, column and flow experiments to assess the behaviour of the particles. We will present the first results of the controlled laboratory experiments for hydrological tracing. We will discuss the results and link it to the differences in particles design. Furthermore, we will draw conclusions and discuss knowledge gaps for future application of silica-protected DNA-tagged micro-particles in hydrological research.

  2. Endothelial cell-derived microparticles induce plasmacytoid dendritic cell maturation: potential implications in inflammatory diseases.

    Science.gov (United States)

    Angelot, Fanny; Seillès, Estelle; Biichlé, Sabeha; Berda, Yael; Gaugler, Béatrice; Plumas, Joel; Chaperot, Laurence; Dignat-George, Françoise; Tiberghien, Pierre; Saas, Philippe; Garnache-Ottou, Francine

    2009-11-01

    Increased circulating endothelial microparticles, resulting from vascular endothelium dysfunction, and plasmacytoid dendritic cell activation are both encountered in common inflammatory disorders. The aim of our study was to determine whether interactions between endothelial microparticles and plasmacytoid dendritic cells could contribute to such pathologies. Microparticles generated from endothelial cell lines, platelets or activated T cells were incubated with human plasmacytoid dendritic cells sorted from healthy donor blood or with monocyte-derived dendritic cells. Dendritic cell maturation was evaluated by flow cytometry, cytokine secretion as well as naive T-cell activation and polarization. Labeled microparticles were also used to study cellular interactions. Endothelial microparticles induced plasmacytoid dendritic cell maturation. In contrast, conventional dendritic cells were resistant to endothelial microparticle-induced maturation. In addition to upregulation of co-stimulatory molecules, endothelial microparticle-matured plasmacytoid dendritic cells secreted inflammatory cytokines (interleukins 6 and 8, but no interferon-alpha) and also induced allogeneic naive CD4(+) T cells to proliferate and to produce type 1 cytokines such as interferon-gamma and tumor necrosis factor-alpha. Endothelial microparticle endocytosis by plasmacytoid dendritic cells appeared to be required for plasmacytoid dendritic cell maturation. Importantly, the ability of endothelial microparticles to induce plasmacytoid dendritic cells to mature was specific as microparticles derived from activated T cells or platelets (the major source of circulating microparticules in healthy subjects) did not induce such plasmacytoid dendritic cell maturation. Our data show that endothelial microparticles specifically induce plasmacytoid dendritic cell maturation and production of inflammatory cytokines. This novel activation pathway may be implicated in various inflammatory disorders and

  3. Microparticles variability in fresh frozen plasma: preparation protocol and storage time effects.

    Science.gov (United States)

    Kriebardis, Anastasios G; Antonelou, Marianna H; Georgatzakou, Hara T; Tzounakas, Vassilis L; Stamoulis, Konstantinos E; Papassideri, Issidora S

    2016-05-01

    Extracellular vesicles or microparticles exhibiting procoagulant and thrombogenic activity may contribute to the haemostatic potential of fresh frozen plasma. Fresh frozen plasma was prepared from platelet-rich plasma at 20 °C (Group-1 donors) or directly from whole blood at 4 °C (Group-2 donors). Each unit was aseptically divided into three parts, stored frozen for specific periods of time, and analysed by flow cytometry for procoagulant activity immediately after thaw or following post-thaw storage for 24 h at 4 °C. Donors' haematologic, biochemical and life-style profiles as well as circulating microparticles were analysed in parallel. Circulating microparticles exhibited a considerable interdonor but not intergroup variation. Fresh frozen plasma units were enriched in microparticles compared to plasma in vivo. Duration of storage significantly affected platelet- and red cell-derived microparticles. Fresh frozen plasma prepared directly from whole blood contained more residual platelets and more platelet-derived microparticles compared to fresh frozen plasma prepared from platelet-rich plasma. Consequently, there was a statistically significant difference in total, platelet- and red cell-derived microparticles between the two preparation protocols over storage time in the freezer. Preservation of the thawed units for 24 h at 4 °C did not significantly alter microparticle accumulation. Microparticle accumulation and anti-oxidant capacity of fresh frozen plasma was positively or negatively correlated, respectively, with the level of circulating microparticles in individual donors. The preparation protocol and the duration of storage in the freezer, independently and in combination, influenced the accumulation of microparticles in fresh frozen plasma units. In contrast, storage of thawed units for 24 h at 4 °C had no significant effect on the concentration of microparticles.

  4. One-step magnetic modification of non-magnetic solid materials

    Czech Academy of Sciences Publication Activity Database

    Šafařík, Ivo; Šafaříková, Miroslava

    2014-01-01

    Roč. 105, č. 1 (2014), s. 104-107 ISSN 1862-5282 R&D Projects: GA MŠk LH12190 Institutional support: RVO:67179843 Keywords : magnetic iron oxide microparticles * microwave assisted synthesis * postmagnetization * magentic separation Subject RIV: EI - Biotechnology ; Bionics Impact factor: 0.639, year: 2014

  5. pH-Sensitive Microparticles with Matrix-Dispersed Active Agent

    Science.gov (United States)

    Li, Wenyan (Inventor); Buhrow, Jerry W. (Inventor); Jolley, Scott T. (Inventor); Calle, Luz M. (Inventor)

    2014-01-01

    Methods to produce pH-sensitive microparticles that have an active agent dispersed in a polymer matrix have certain advantages over microcapsules with an active agent encapsulated in an interior compartment/core inside of a polymer wall. The current invention relates to pH-sensitive microparticles that have a corrosion-detecting or corrosion-inhibiting active agent or active agents dispersed within a polymer matrix of the microparticles. The pH-sensitive microparticles can be used in various coating compositions on metal objects for corrosion detecting and/or inhibiting.

  6. Improved circulating microparticle analysis in acid-citrate dextrose (ACD) anticoagulant tube.

    Science.gov (United States)

    György, Bence; Pálóczi, Krisztina; Kovács, Alexandra; Barabás, Eszter; Bekő, Gabriella; Várnai, Katalin; Pállinger, Éva; Szabó-Taylor, Katalin; Szabó, Tamás G; Kiss, Attila A; Falus, András; Buzás, Edit I

    2014-02-01

    Recently extracellular vesicles (exosomes, microparticles also referred to as microvesicles and apoptotic bodies) have attracted substantial interest as potential biomarkers and therapeutic vehicles. However, analysis of microparticles in biological fluids is confounded by many factors such as the activation of cells in the blood collection tube that leads to in vitro vesiculation. In this study we aimed at identifying an anticoagulant that prevents in vitro vesiculation in blood plasma samples. We compared the levels of platelet microparticles and non-platelet-derived microparticles in platelet-free plasma samples of healthy donors. Platelet-free plasma samples were isolated using different anticoagulant tubes, and were analyzed by flow cytometry and Zymuphen assay. The extent of in vitro vesiculation was compared in citrate and acid-citrate-dextrose (ACD) tubes. Agitation and storage of blood samples at 37 °C for 1 hour induced a strong release of both platelet microparticles and non-platelet-derived microparticles. Strikingly, in vitro vesiculation related to blood sample handling and storage was prevented in samples in ACD tubes. Importantly, microparticle levels elevated in vivo remained detectable in ACD tubes. We propose the general use of the ACD tube instead of other conventional anticoagulant tubes for the assessment of plasma microparticles since it gives a more realistic picture of the in vivo levels of circulating microparticles and does not interfere with downstream protein or RNA analyses. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Counter-Propagating Optical Trapping System for Size and Refractive Index Measurement of Microparticles

    National Research Council Canada - National Science Library

    Flynn, Richard A; Shao, Bing; Chachisvilis, Mirianas; Ozkan, Mihrimah; Esener, Sadik C

    2005-01-01

    .... Different from the current best technique for microparticles refractive index measurement, refractometry, a bulk technique requiring changing the fluid composition of the sample, our optical trap...

  8. On the origin of microparticles: From “platelet dust” to mediators of intercellular communication

    Science.gov (United States)

    Hargett, Leslie A.; Bauer, Natalie N.

    2013-01-01

    Microparticles are submicron vesicles shed from a variety of cells. Peter Wolf first identified microparticles in the midst of ongoing blood coagulation research in 1967 as a product of platelets. He termed them platelet dust. Although initially thought to be useless cellular trash, decades of research focused on the tiny vesicles have defined their roles as participators in coagulation, cellular signaling, vascular injury, and homeostasis. The purpose of this review is to highlight the science leading up to the discovery of microparticles, feature discoveries made by key contributors to the field of microparticle research, and discuss their positive and negative impact on the pulmonary circulation. PMID:24015332

  9. Encapsulation of antigen-loaded silica nanoparticles into microparticles for intradermal powder injection.

    Science.gov (United States)

    Deng, Yibin; Mathaes, Roman; Winter, Gerhard; Engert, Julia

    2014-10-15

    Epidermal powder immunisation (EPI) is being investigated as a promising needle-free delivery methods for vaccination. The objective of this work was to prepare a nanoparticles-in-microparticles (nano-in-micro) system, integrating the advantages of nanoparticles and microparticles into one vaccine delivery system for epidermal powder immunisation. Cationic mesoporous silica nanoparticles (MSNP-NH2) were prepared and loaded with ovalbumin as a model antigen. Loading was driven by electrostatic interactions. Ovalbumin-loaded silica nanoparticles were subsequently formulated into sugar-based microparticles by spray-freeze-drying. The obtained microparticles meet the size requirement for EPI. Confocal microscopy was used to demonstrate that the nanoparticles are homogeneously distributed in the microparticles. Furthermore, the silica nanoparticles in the dry microparticles can be re-dispersed in aqueous solution showing no aggregation. The recovered ovalbumin shows integrity compared to native ovalbumin. The present nano-in-micro system allows (1) nanoparticles to be immobilized and finely distributed in microparticles, (2) microparticle formation and (3) re-dispersion of nanoparticles without subsequent aggregation. The nanoparticles inside microparticles can (1) adsorb proteins to cationic shell/surface voids in spray-dried products without detriment to ovalbumin stability, (2) deliver antigens in nano-sized modes to allow recognition by the immune system. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Carrier concentration induced ferromagnetism in semiconductors

    International Nuclear Information System (INIS)

    Story, T.

    2007-01-01

    In semiconductor spintronics the key materials issue concerns ferromagnetic semiconductors that would, in particular, permit an integration (in a single multilayer heterostructure) of standard electronic functions of semiconductors with magnetic memory function. Although classical semiconductor materials, such as Si or GaAs, are nonmagnetic, upon substitutional incorporation of magnetic ions (typically of a few atomic percents of Mn 2+ ions) and very heavy doping with conducting carriers (at the level of 10 20 - 10 21 cm -3 ) a ferromagnetic transition can be induced in such diluted magnetic semiconductors (also known as semimagnetic semiconductors). In the lecture the spectacular experimental observations of carrier concentration induced ferromagnetism will be discussed for three model semiconductor crystals. p - Ga 1-x Mn x As currently the most actively studied and most perspective ferromagnetic semiconductor of III-V group, in which ferromagnetism appears due to Mn ions providing both local magnetic moments and acting as acceptor centers. p - Sn 1-x Mn x Te and p - Ge 1-x Mn x Te classical diluted magnetic semiconductors of IV-VI group, in which paramagnet-ferromagnet and ferromagnet-spin glass transitions are found for very high hole concentration. n - Eu 1-x Gd x Te mixed magnetic crystals, in which the substitution of Gd 3+ ions for Eu 2+ ions creates very high electron concentration and transforms antiferromagnetic EuTe (insulating compound) into ferromagnetic n-type semiconductor alloy. For each of these materials systems the key physical features will be discussed concerning: local magnetic moments formation, magnetic phase diagram as a function of magnetic ions and carrier concentration as well as Curie temperature and magnetic anisotropy engineering. Various theoretical models proposed to explain the effect of carrier concentration induced ferromagnetism in semiconductors will be briefly discussed involving mean field approaches based on Zener and RKKY

  11. Peptide-Carrier Conjugation

    DEFF Research Database (Denmark)

    Hansen, Paul Robert

    2015-01-01

    To produce antibodies against synthetic peptides it is necessary to couple them to a protein carrier. This chapter provides a nonspecialist overview of peptide-carrier conjugation. Furthermore, a protocol for coupling cysteine-containing peptides to bovine serum albumin is outlined....

  12. Air Carrier Traffic Statistics.

    Science.gov (United States)

    2013-11-01

    This report contains airline operating statistics for large certificated air carriers based on data reported to U.S. Department of Transportation (DOT) by carriers that hold a certificate issued under Section 401 of the Federal Aviation Act of 1958 a...

  13. Air Carrier Traffic Statistics.

    Science.gov (United States)

    2012-07-01

    This report contains airline operating statistics for large certificated air carriers based on data reported to U.S. Department of Transportation (DOT) by carriers that hold a certificate issued under Section 401 of the Federal Aviation Act of 1958 a...

  14. Fatty acids profile of chia oil-loaded lipid microparticles

    Directory of Open Access Journals (Sweden)

    M. F. Souza

    Full Text Available ABSTRACT Encapsulation of poly-unsaturated fatty acid (PUFAis an alternative to increase its stability during processing and storage. Chia (Salvia hispanica L. oil is a reliable source of both omega-3 and omega-6 and its encapsulation must be better evaluated as an effort to increase the number of foodstuffs containing PUFAs to consumers. In this work chia oil was extracted and encapsulated in stearic acid microparticles by the hot homogenization technique. UV-Vis spectroscopy coupled with Multivariate Curve Resolution with Alternating Least-Squares methodology demonstrated that no oil degradation or tocopherol loss occurred during heating. After lyophilization, the fatty acids profile of the oil-loaded microparticles was determined by gas chromatography and compared to in natura oil. Both omega-3 and omega-6 were effectively encapsulated, keeping the same omega-3:omega-6 ratio presented in the in natura oil. Calorimetric analysis confirmed that encapsulation improved the thermal stability of the chia oil.

  15. Self-organized internal architectures of chiral micro-particles

    International Nuclear Information System (INIS)

    Provenzano, Clementina; Mazzulla, Alfredo; Desiderio, Giovanni; Pagliusi, Pasquale; De Santo, Maria P.; Cipparrone, Gabriella; Perrotta, Ida

    2014-01-01

    The internal architecture of polymeric self-assembled chiral micro-particles is studied by exploring the effect of the chirality, of the particle sizes, and of the interface/surface properties in the ordering of the helicoidal planes. The experimental investigations, performed by means of different microscopy techniques, show that the polymeric beads, resulting from light induced polymerization of cholesteric liquid crystal droplets, preserve both the spherical shape and the internal self-organized structures. The method used to create the micro-particles with controlled internal chiral architectures presents great flexibility providing several advantages connected to the acquired optical and photonics capabilities and allowing to envisage novel strategies for the development of chiral colloidal systems and materials

  16. Microparticles based on natural and synthetic polymers for ophthalmic applications.

    Science.gov (United States)

    Tataru, G; Popa, M; Costin, D; Desbrieres, J

    2012-05-01

    Sodium salt of carboxymethylcellulose/poly(vinyl alcohol) particles suitable for application in ocular drug administration were prepared by crosslinking with epichlorohydrin in an alkaline medium, in reverse emulsion. The influence of parameters related with the particles elaboration process (ratio between polymer mixture and crosslinking agent, concentration of polymer solution, duration of crosslinking reaction, stirring intensity, etc.) based on their composition, size, and swelling ability was studied. Obtained microparticles fulfill the requirements for biomaterials-they are formed from biocompatible polymers; the acute toxicity value (LD(50)) is high enough to consider these materials as weakly toxic (hence able to introduce within the organism); they are able to include and release drugs in a controlled way. The in vivo adrenalin ocular delivery from the microparticles was tested on voluntary human patient. The particles showed good adhesion properties without irritation to the patient and proved the capability to treat the ocular congestion. Copyright © 2012 Wiley Periodicals, Inc.

  17. Principles of transverse flow fractionation of microparticles in superhydrophobic channels.

    Science.gov (United States)

    Asmolov, Evgeny S; Dubov, Alexander L; Nizkaya, Tatiana V; Kuehne, Alexander J C; Vinogradova, Olga I

    2015-07-07

    We propose a concept of fractionation of micron-sized particles in a microfluidic device with a bottom wall decorated by superhydrophobic stripes. The stripes are oriented at an angle α to the direction of a driving force, G, which generally includes an applied pressure gradient and gravity. Separation relies on the initial sedimentation of particles under gravity in the main forward flow, and their subsequent lateral deflection near a superhydrophobic wall due to generation of a secondary flow transverse to G. We provide some theoretical arguments allowing us to quantify the transverse displacement of particles in the microfluidic channel, and confirm the validity of theoretical predictions in test experiments with monodisperse fractions of microparticles. Our results can guide the design of superhydrophobic microfluidic devices for efficient sorting of microparticles with a relatively small difference in size and density.

  18. Magnetic GMI sensor for detection of biomolecules

    International Nuclear Information System (INIS)

    Chiriac, Horia; Tibu, Mihai; Moga, Anca-Eugenia; Herea, Dumitru D.

    2005-01-01

    A magnetic sensor based on the giant magnetoimpedance (GMI) effect for the detection of biomolecules was made with a CoFeSiB amorphous magnetic microwire as sensing element. Using soft ferromagnetic cobalt microparticles and field sensitivities of the impedance of about 2.5%/A m -1 in the very low field region (less than 200 A m -1 ) at frequencies close to 10 MHz, a highly sensitive response was measured, appropriate for the detection of low biomolecule concentrations

  19. Microfluidic device for the assembly and transport of microparticles

    Science.gov (United States)

    James, Conrad D [Albuquerque, NM; Kumar, Anil [Framingham, MA; Khusid, Boris [New Providence, NJ; Acrivos, Andreas [Stanford, CA

    2010-06-29

    A microfluidic device comprising independently addressable arrays of interdigitated electrodes can be used to assembly and transport large-scale microparticle structures. The device and method uses collective phenomena in a negatively polarized suspension exposed to a high-gradient strong ac electric field to assemble the particles into predetermined locations and then transport them collectively to a work area for final assembly by sequentially energizing the electrode arrays.

  20. Application of Flow Focusing to the Break-Up of a Magnetite Suspension Jet for the Production of Paramagnetic Microparticles

    International Nuclear Information System (INIS)

    Banderas, L.M.; Arevalo, M.F.; Banderas, L.M.; Flores-Mosquera, M.; Arevalo, M.F.; Ganan-Calvo, A.M.; Gonzalez-Prieto, R.; Rodriguez-Gi, A.; Chavez, S.; Ganan-Calvo, A.M.

    2009-01-01

    Paramagnetic particles offer an extensive improvement in the magnetic separation or purification of a wide variety of protein molecules. Most commercial paramagnetic particles are synthesized by laborious and costly procedures. A straightforward production of paramagnetic microparticles with homogeneous and selectable sizes using flow focusing (FF) technology is described in this work. The development of an initial formulation of a stable iron oxide suspension compatible with the FF requirements is also reported. The obtained particles, below 10 microns in diameter and presenting smooth and reactive surface, were codified with an organic fluorophore and showed excellent properties for covalent attachment of biomolecules such as proteins and its subsequent recognition by flow cytometry. Furthermore, particles with suitable magnetite content resulted as well-suited for commercial magnet separators for these purposes

  1. Phospholipid composition of cell-derived microparticles determined by one-dimensional high-performance thin-layer chromatography

    NARCIS (Netherlands)

    Weerheim, A. M.; Kolb, A. M.; Sturk, A.; Nieuwland, R.

    2002-01-01

    Microparticles in the circulation activate the coagulation system and may activate the complement system via C-reactive protein upon conversion of membrane phospholipids by phospholipases. We developed a sensitive and reproducible method to determine the phospholipid composition of microparticles.

  2. Restructuring of microparticles in nuclear ceramic materials. Part II. Analytical derivation of the steady-state size distribution

    International Nuclear Information System (INIS)

    Lameiras, F.S.

    1991-01-01

    Two fundamental principles were assumed to govern the restructuring of microparticles: minimization and uniformization in space of the interface energy. Five fundamental ways, independent of each other and acting simultaneously, were identified, through which a microparticle set can be restructured according to the fundamental principles: a) decrease of the number of microparticles; b) modification of the microparticle size distribution; c) modification of the microparticles from tending to an equiaxial one; d) tendency to the distribution of microparticles uniform in space; e) tendency to the distribution of the interface energy uniform per microparticle. This presents an analytical derivation of the steady-state microparticle size distribution due to the simultaneous action of the fundamental ways b) and e). (author)

  3. Characterization of hybrid microparticles/Montmorillonite composite with raspberry-like morphology for Atorvastatin controlled release.

    Science.gov (United States)

    García-Guzmán, Perla; Medina-Torres, Luis; Calderas, Fausto; Bernad-Bernad, María Josefa; Gracia-Mora, Jesús; Mena, Baltasar; Manero, Octavio

    2018-07-01

    In this work, we prepared a novel composite based on hybrid gelatin carriers and montmorillonite clay (MMT) to analyze its viability as controlled drug delivery system. The objective of this research involves the characterization of composites formed by structured lipid-gelatin micro-particles (MP) and MMT clay. This analysis included the evaluation of the composite according to its rheological properties, morphology (SEM), particle size, XRD, FT-IR, and in vitro drug release. The effect of pH in the properties of the composite is evaluated. A novel raspberry-like or armor MP/MMT clay composite is reported, in which the pH has an important effect on the final structure of the composite for ad-hoc drug delivery systems. For pH values below the isoelectric point, we obtained defined morphologies with entrapment efficiencies up to 67%. The pH level controls the MP/MMT composite release mechanism, restringing drug release in the stomach-like environment. Intended for oral administration, these results evidence that the MP/MMT composite represents an attractive alternative for intestinal-colonic controlled drug delivery systems. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Some mechanisms for the formation of octopus-shaped iron micro-particles

    International Nuclear Information System (INIS)

    Bica, Ioan

    2004-01-01

    Fluid spheres (micro-spheres or/and drops) are formed out of the metallic solid (the carbon steel semi-finished product) in the argon plasma of the transferred electric arc. For short intervals of time, the spheres are at rest with relation to vapors. The movement of the vapors around the spheres is in the same plane. It consists of a movement around a circle combined with the movement produced by a definitely located whirl. The molar concentration of the vapors is small in comparison with the molar density of the mixture formed of vapors and gas. At the intersection of the sphere and the plane of movement of the vapors, distinct stagnation point is formed. They constitute points of the beginning/and end of the current lines. Each current line is a carrier of a vapor cylinder. In time, the cylinder-gas interface reaches points of temperature equal to that of the 'dew point' for iron. On this occasion a liquid membrane is formed. It delimits the vapor-gas mixture from the rest of the gas. Subsequent to the process of diffusion in non-stationary condition, the membrane becomes thicker and no vapors exist inside the tube. Needle-shaped micro-tubes are formed, in liquid phase, around the fluid sphere. By solidification, micro-particles occur, consisting of a central nucleus around which ligaments branch out

  5. Some mechanisms for the formation of octopus-shaped iron micro-particles

    Science.gov (United States)

    Bica, Ioan

    2004-08-01

    Fluid spheres (micro-spheres or/and drops) are formed out of the metallic solid (the carbon steel semi-finished product) in the argon plasma of the transferred electric arc. For short intervals of time, the spheres are at rest with relation to vapors. The movement of the vapors around the spheres is in the same plane. It consists of a movement around a circle combined with the movement produced by a definitely located whirl. The molar concentration of the vapors is small in comparison with the molar density of the mixture formed of vapors and gas. At the intersection of the sphere and the plane of movement of the vapors, distinct stagnation point is formed. They constitute points of the beginning/and end of the current lines. Each current line is a carrier of a vapor cylinder. In time, the cylinder-gas interface reaches points of temperature equal to that of the "dew point" for iron. On this occasion a liquid membrane is formed. It delimits the vapor-gas mixture from the rest of the gas. Subsequent to the process of diffusion in non-stationary condition, the membrane becomes thicker and no vapors exist inside the tube. Needle-shaped micro-tubes are formed, in liquid phase, around the fluid sphere. By solidification, micro-particles occur, consisting of a central nucleus around which ligaments branch out.

  6. Some mechanisms for the formation of octopus-shaped iron micro-particles

    Energy Technology Data Exchange (ETDEWEB)

    Bica, Ioan E-mail: ibica2@yahoo.com

    2004-08-01

    Fluid spheres (micro-spheres or/and drops) are formed out of the metallic solid (the carbon steel semi-finished product) in the argon plasma of the transferred electric arc. For short intervals of time, the spheres are at rest with relation to vapors. The movement of the vapors around the spheres is in the same plane. It consists of a movement around a circle combined with the movement produced by a definitely located whirl. The molar concentration of the vapors is small in comparison with the molar density of the mixture formed of vapors and gas. At the intersection of the sphere and the plane of movement of the vapors, distinct stagnation point is formed. They constitute points of the beginning/and end of the current lines. Each current line is a carrier of a vapor cylinder. In time, the cylinder-gas interface reaches points of temperature equal to that of the 'dew point' for iron. On this occasion a liquid membrane is formed. It delimits the vapor-gas mixture from the rest of the gas. Subsequent to the process of diffusion in non-stationary condition, the membrane becomes thicker and no vapors exist inside the tube. Needle-shaped micro-tubes are formed, in liquid phase, around the fluid sphere. By solidification, micro-particles occur, consisting of a central nucleus around which ligaments branch out.

  7. Modulating thrombotic diathesis in hereditary thrombophilia and antiphospholipid antibody syndrome: a role for circulating microparticles?

    Science.gov (United States)

    Campello, Elena; Radu, Claudia M; Spiezia, Luca; Simioni, Paolo

    2017-06-27

    Over the past decades, there have been great advances in the understanding of the pathogenesis of venous thromboembolism (VTE) in patients with inherited and acquired thrombophilia [mainly antiphospholipid antibody syndrome (APS)]. However, a number of questions remain unanswered. Prognostic markers capable of estimating the individual VTE risk would be of great use. Microparticles (MPs) are sub-micron membrane vesicles constitutively released from the surface of cells after cellular activation and apoptosis. The effects of MPs on thrombogenesis include the exposure of phopshatidylserine and the expression of tissue factor and MPs have been described in clinical studies as possible diagnostic and prognostic biomarkers for VTE. This review will provide a novel perspective on the current knowledge and research trends on the possible role of MPs in hereditary thrombophilia and APS. Basically, the published data show that circulating MPs may contribute to the development of VTE in thrombophilic carriers, both in mild and severe states. Moreover, the presence of endothelial-MPs and platelet-MPs has been described in antiphospholipid syndrome and seems to be directly linked to antiphospholipid antibodies and not to other underlying autoimmune disorders or the thrombotic event itself. In conclusion, circulating MPs may constitute an epiphenomenon of thrombophilia itself and could be up-regulated in acute particular conditions, promoting a global prothrombotic state up to the threshold of the clinical relevant thrombotic event.

  8. Recent advances in engineering microparticles and their nascent utilization in biomedical delivery and diagnostic applications.

    Science.gov (United States)

    Choi, Andrew; Seo, Kyoung Duck; Kim, Do Wan; Kim, Bum Chang; Kim, Dong Sung

    2017-02-14

    Complex microparticles (MPs) bearing unique characteristics such as well-tailored sizes, various morphologies, and multi-compartments have been attempted to be produced by many researchers in the past decades. However, a conventionally used method of fabricating MPs, emulsion polymerization, has a limitation in achieving the aforementioned characteristics and several approaches such as the microfluidics-assisted (droplet-based microfluidics and flow lithography-based microfluidics), electrohydrodynamics (EHD)-based, centrifugation-based, and template-based methods have been recently suggested to overcome this limitation. The outstanding features of complex MPs engineered through these suggested methods have provided new opportunities for MPs to be applied in a wider range of applications including cell carriers, drug delivery agents, active pigments for display, microsensors, interface stabilizers, and catalyst substrates. Overall, the engineered MPs expose their potential particularly in the field of biomedical engineering as the increased complexity in the engineered MPs fulfills well the requirements of the high-end applications. This review outlines the current trends of newly developed techniques used for engineered MPs fabrication and focuses on the current state of engineered MPs in biomedical applications.

  9. Development and Characterization of Nanoembedded Microparticles for Pulmonary Delivery of Antitubercular Drugs against Experimental Tuberculosis.

    Science.gov (United States)

    Goyal, Amit Kumar; Garg, Tarun; Rath, Goutam; Gupta, Umesh Datta; Gupta, Pushpa

    2015-11-02

    The foremost objective of the present research study was to develop and evaluate the potential of rifampicin (RIF) and isoniazid (INH) loaded spray dried nanoembedded microparticles against experimental tuberculosis (TB). In this study, RIF-INH loaded various formulations (chitosan, guar gum, mannan, and guar gum coated chitosan) were prepared by spray drying and characterized on the basis of in vitro as well as in vivo studies. Results showed that guar gum spray dried particles showed uniform size distribution with smooth surface as compare to mannan formulations. Guar gum batches exhibited excellent flow ability attributed to their optimum moisture content and uniform size distribution. The drug release showed the biphasic pattern of release, i.e., initial burst followed by a sustained release pattern. The preferential uptake of guar gum coated formulations suggested the presence and selective uptake capability of mannose moiety to the specific cell surface of macrophages. In vivo lung distribution study showed that guar gum coated chitosan (GCNP) batches demonstrated prolonged residence at the target site and thereby improve the therapeutic utility of drug with a significant reduction in systemic toxicity. Optimized drug loaded GCNP formulation has resulted in almost 5-fold reduction of the number of bacilli as compared to control group. Histopathology study also demonstrated that none of the treated groups show any evidence of lung tissue abnormality. Hence, GCNPs could be a promising carrier for selective delivery of antitubercular drugs to alveolar macrophages with the interception of minimal side effects, for efficient management of TB.

  10. Spray drying of silica microparticles for sustained release application with a new sol-gel precursor.

    Science.gov (United States)

    Wang, Bifeng; Friess, Wolfgang

    2017-10-30

    A new precursor, tetrakis(2-methoxyethyl) orthosilicate (TMEOS) was used to fabricate microparticles for sustained release application, specifically for biopharmaceuticals, by spray drying. The advantages of TMEOS over the currently applied precursors are its water solubility and hydrolysis at moderate pH without the need of organic solvents or catalyzers. Thus a detrimental effect on biomolecular drug is avoided. By generating spray-dried silica particles encapsulating the high molecular weight model compound FITC-dextran 150 via the nano spray dryer Büchi-90, we demonstrated how formulation parameters affect and enable control of drug release properties. The implemented strategies to regulate release included incorporating different quantities of dextrans with varying molecular weight as well as adjusting the pH of the precursor solution to modify the internal microstructures. The addition of dextran significantly altered the released amount, while the release became faster with increasing dextran molecular weight. A sustained release over 35days could be achieved with addition of 60 kD dextran. The rate of FITC-Dextran 150 release from the dextran 60 containing particles decreased with higher precursor solution pH. In conclusion, the new precursor TMEOS presents a promising alternative sol-gel technology based carrier material for sustained release application of high molecular weight biopharmaceutical drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Thulium-170-labeled microparticles for local radiotherapy: preliminary studies.

    Science.gov (United States)

    Polyak, Andras; Das, Tapas; Chakraborty, Sudipta; Kiraly, Reka; Dabasi, Gabriella; Joba, Robert Peter; Jakab, Csaba; Thuroczy, Julianna; Postenyi, Zita; Haasz, Veronika; Janoki, Gergely; Janoki, Gyozo A; Pillai, Maroor R A; Balogh, Lajos

    2014-10-01

    The present article describes the preparation, characterization, and biological evaluation of Thulium-170 ((170)Tm) [T1/2 = 128.4 days; Eβmax = 968 keV; Eγ = 84 keV (3.26%)] labeled tin oxide microparticles for its possible use in radiation synovectomy (RSV) of medium-sized joints. (170)Tm was produced by irradiation of natural thulium oxide target. 170Tm-labeled microparticles were synthesized with high yield and radionuclidic purity (> 99%) along with excellent in vitro stability by following a simple process. Particle sizes and morphology of the radiolabeled particles were examined by light microscope, dynamic light scattering, and transmission electron microscope and found to be of stable spherical morphology within the range of 1.4-3.2 μm. The preparation was injected into the knee joints of healthy Beagle dogs intraarticularly for biological studies. Serial whole-body and regional images were taken by single-photon-emission computed tomography (SPECT) and SPECT-CT cameras up to 9 months postadministration, which showed very low leakage (compound did not show any possible radiotoxicological effect. These preliminary studies showed that 170Tm-labeled microparticles could be a promising nontoxic and effective radiopharmaceutical for RSV applications or later local antitumor therapy.

  12. Functionalized diatom silica microparticles for removal of mercury ions

    International Nuclear Information System (INIS)

    Yu Yang; Addai-Mensah, Jonas; Losic, Dusan

    2012-01-01

    Diatom silica microparticles were chemically modified with self-assembled monolayers of 3-mercaptopropyl-trimethoxysilane (MPTMS), 3-aminopropyl-trimethoxysilane (APTES) and n-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPTMS), and their application for the adsorption of mercury ions (Hg(II)) is demonstrated. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy analyses revealed that the functional groups (–SH or –NH 2 ) were successfully grafted onto the diatom silica surface. The kinetics and efficiency of Hg(II) adsorption were markedly improved by the chemical functionalization of diatom microparticles. The relationship among the type of functional groups, pH and adsorption efficiency of mercury ions was established. The Hg(II) adsorption reached equilibrium within 60 min with maximum adsorption capacities of 185.2, 131.7 and 169.5 mg g -1 for particles functionalized with MPTMS, APTES and AEAPTMS, respectively. The adsorption behavior followed a pseudo-second-order reaction model and Langmuirian isotherm. These results show that mercapto- or amino-functionalized diatom microparticles are promising natural, cost-effective and environmentally benign adsorbents suitable for the removal of mercury ions from aqueous solutions.

  13. Study of Formulation Variables Influencing Polymeric Microparticles by Experimental Design

    Directory of Open Access Journals (Sweden)

    Jitendra B. Naik

    2014-04-01

    Full Text Available The objective of this study was to prepare diclofenac sodium loaded microparticles by single emulsion [oil-in-water (o/w] solvent evaporation method. The 22 experimental design methodology was used to evaluate the effect of two formulation variables on microspheres properties using the Design-Expert® software and evaluated for their particle size, morphology, and encapsulation efficiency and in vitro drug release. The graphical and mathematical analysis of the design showed that the independent variables were a significant effect on the encapsulation efficiency and drug release of microparticles. The low magnitudes of error and significant values of R2 prove the high prognostic ability of the design. The microspheres showed high encapsulation efficiency with an increase in the amount of polymer and decrease in the amount of PVA in the formulation. The particles were found to be spherical with smooth surface. Prolonged drug release and enhancement of encapsulation efficiency of polymeric microparticles can be successfully obtained with an application of experimental design technique.

  14. Moldless PEGDA-Based Optoelectrofluidic Platform for Microparticle Selection

    Directory of Open Access Journals (Sweden)

    Shih-Mo Yang

    2011-01-01

    Full Text Available This paper reports on an optoelectrofluidic platform which consists of the organic photoconductive material, titanium oxide phthalocyanine (TiOPc, and the photocrosslinkable polymer, poly (ethylene glycol diacrylate (PEGDA. TiOPc simplifies the fabrication process of the optoelectronic chip due to requiring only a single spin-coating step. PEGDA is applied to embed the moldless PEGDA-based microchannel between the top ITO glass and the bottom TiOPc substrate. A real-time control interface via a touch panel screen is utilized to select the target 15 μm polystyrene particles. When the microparticles flow to an illuminating light bar, which is oblique to the microfluidic flow path, the lateral driving force diverts the microparticles. Two light patterns, the switching oblique light bar and the optoelectronic ladder phenomenon, are designed to demonstrate the features. This work integrating the new material design, TiOPc and PEGDA, and the ability of mobile microparticle manipulation demonstrates the potential of optoelectronic approach.

  15. Circulating cell-derived microparticles in women with pregnancy loss.

    Science.gov (United States)

    Alijotas-Reig, Jaume; Palacio-Garcia, Carles; Farran-Codina, Immaculada; Zarzoso, Cristina; Cabero-Roura, Luis; Vilardell-Tarres, Miquel

    2011-09-01

    To analyze cell-derived microparticles (cMP) in pregnancy loss (PL), both recurrent miscarriages (RM) and unexplained fetal loss (UFL). Non-matched case-control study was performed at Vall d'Hebron Hospital. Cell-derived microparticles of 53 PL cases, 30 with RM, 16 with UFL, and 7 (RM + UFL), were compared to 38 healthy pregnant women. Twenty healthy non-pregnant women act as controls. Cell-derived microparticles were analyzed through flow cytometry. Results are given as total annexin (A5+), endothelial-(CD144+/CD31+ CD41-), platelet-(CD41+), leukocyte-(CD45+) and CD41- c-MP/μL of plasma. Antiphospholipid antibodies (aPLA) were analyzed according to established methods. Comparing PL versus healthy pregnant, we observed a significant endothelial cMP decrease in PL. When comparing RM subgroup with controls, we observed significant decreases in endothelial cMP. When comparing the PL positive for aPLA versus PL-aPLA-negative, no cMP numbering differences were seen. Pregnancy loss seems to be related to endothelial cell activation and/or consumption. A relationship between aPLA and cMP could not be demonstrated. © 2011 John Wiley & Sons A/S.

  16. Interface recombination influence on carrier transport

    International Nuclear Information System (INIS)

    Konin, A

    2013-01-01

    A theory of interface recombination in the semiconductor–semiconductor junction is developed. The interface recombination rate dependence on the nonequilibrium carrier densities is derived on the basis of a model in which the interface recombination occurs through the mechanism of trapping. The general relation between the interface recombination parameters at small carrier density deviation from the equilibrium ones is obtained. The validity of this relation is proved considering the generation of the Hall electric field in the extrinsic semiconductor sample. The anomalous Hall electromotive force in a weak magnetic field was investigated and interpreted by means of a new interface recombination model. The experimental data corroborate the developed theory. (paper)

  17. Magnetic

    Science.gov (United States)

    Aboud, Essam; El-Masry, Nabil; Qaddah, Atef; Alqahtani, Faisal; Moufti, Mohammed R. H.

    2015-06-01

    The Rahat volcanic field represents one of the widely distributed Cenozoic volcanic fields across the western regions of the Arabian Peninsula. Its human significance stems from the fact that its northern fringes, where the historical eruption of 1256 A.D. took place, are very close to the holy city of Al-Madinah Al-Monawarah. In the present work, we analyzed aeromagnetic data from the northern part of Rahat volcanic field as well as carried out a ground gravity survey. A joint interpretation and inversion of gravity and magnetic data were used to estimate the thickness of the lava flows, delineate the subsurface structures of the study area, and estimate the depth to basement using various geophysical methods, such as Tilt Derivative, Euler Deconvolution and 2D modeling inversion. Results indicated that the thickness of the lava flows in the study area ranges between 100 m (above Sea Level) at the eastern and western boundaries of Rahat Volcanic field and getting deeper at the middle as 300-500 m. It also showed that, major structural trend is in the NW direction (Red Sea trend) with some minor trends in EW direction.

  18. MAGNET

    CERN Multimedia

    Benoit Curé

    The cooling down to the nominal temperature of 4.5 K was achieved at the beginning of August, in conjunction with the completion of the installation work of the connection between the power lines and the coil current leads. The temperature gradient on the first exchanger of the cold box is now kept within the nominal range. A leak of lubricant on a gasket of the helium compressor station installed at the surface was observed and several corrective actions were necessary to bring the situation back to normal. The compressor had to be refilled with lubricant and a regeneration of the filters and adsorbers was necessary. The coil cool down was resumed successfully, and the cryogenics is running since then with all parameters being nominal. Preliminary tests of the 20kA coil power supply were done earlier at full current through the discharge lines into the dump resistors, and with the powering busbars from USC5 to UXC5 without the magnet connected. On Monday evening August 25th, at 8pm, the final commissionin...

  19. MAGNET

    CERN Document Server

    B. Curé

    The first phase of the commissioning ended in August by a triggered fast dump at 3T. All parameters were nominal, and the temperature recovery down to 4.5K was carried out in two days by the cryogenics. In September, series of ramps were achieved up to 3 and finally 3.8T, while checking thoroughly the detectors in the forward region, measuring any movement of and around the HF. After the incident of the LHC accelerator on September 19th, corrective actions could be undertaken in the forward region. When all these displacements were fully characterized and repetitive, with no sign of increments in displacement at each field ramp, it was possible to start the CRAFT, Cosmic Run at Four Tesla (which was in fact at 3.8T). The magnet was ramped up to 18.16kA and the 3 week run went smoothly, with only 4 interruptions: due to the VIP visits on 21st October during the LHC inauguration day; a water leak on the cooling demineralized water circuit, about 1 l/min, that triggered a stop of the cooling pumps, and resulte...

  20. MAGNET

    CERN Multimedia

    Benoit Curé

    2013-01-01

    Maintenance work and consolidation activities on the magnet cryogenics and its power distribution are progressing according to the schedules. The manufacturing of the two new helium compressor frame units has started. The frame units support the valves, all the sensors and the compressors with their motors. This activity is subcontracted. The final installation and the commissioning at CERN are scheduled for March–April 2014. The overhauls of existing cryogenics equipment (compressors, motors) are in progress. The reassembly of the components shall start in early 2014. The helium drier, to be installed on the high-pressure helium piping, has been ordered and will be delivered in the first trimester of 2014. The power distribution for the helium compressors in SH5 on the 3.3kV network is progressing. The 3.3kV switches, between each compressor and its hot spare compressor, are being installed, together with the power cables for the new compressors. The 3.3kV electrical switchboards in SE5 will ...

  1. Microparticle counts in platelet-rich and platelet-free plasma, effect of centrifugation and sample-processing protocols.

    Science.gov (United States)

    Chandler, Wayne L

    2013-03-01

    This study provides the first estimates of microparticle numbers in platelet-rich plasma (PRP) from normal individuals, closer to in-vivo levels, using higher-resolution flow cytometry. We measured platelet (CD41+) and annexin V+ microparticles in fresh and frozen aliquots of PRP, platelet-poor plasma, platelet-free plasma (PFP), and microparticles isolated by high-speed centrifugation. PRP from healthy individuals contained 730,000/μl total microparticles based on light-scattering measurements. A median of 27,000/μl microparticles in PRP were of platelet origin and 120,000/μl annexin V+, and of these, 24,000/μl were dual-positive procoagulant platelet microparticles. Double centrifugation of PRP removed 99% of platelets, but also 80% of annexin V+ CD41+, 93% of annexin V+ CD41-, and 58% of annexin V- CD41+ microparticles. Loss of microparticles with centrifugation varied from individual to individual. Microparticle counts after isolation by centrifugation and double washing were not significantly different than counts in the original PFP sample, but lower than in PRP. Freeze-thawing of PFP had no effect on platelet microparticle counts, but slightly increased annexin V+, CD41- counts. Freeze-thawing of isolated washed microparticles resulted in a 30-50% increase in annexin V+ microparticles. PRP contains large numbers of cellular microparticles, including platelet and annexin V+ microparticles, which are lost to varying degrees when PRP is double centrifuged to remove platelets. Microparticles remaining in PFP can be recovered by high-speed centrifugation without loss compared to the original PFP sample. Freeze-thawing has variable effects on microparticle counts depending on the sample preparation used.

  2. Magnetically responsive enzyme powders

    Energy Technology Data Exchange (ETDEWEB)

    Pospiskova, Kristyna, E-mail: kristyna.pospiskova@upol.cz [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Safarik, Ivo, E-mail: ivosaf@yahoo.com [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Department of Nanobiotechnology, Institute of Nanobiology and Structural Biology of GCRC, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic)

    2015-04-15

    Powdered enzymes were transformed into their insoluble magnetic derivatives retaining their catalytic activity. Enzyme powders (e.g., trypsin and lipase) were suspended in various liquid media not allowing their solubilization (e.g., saturated ammonium sulfate and highly concentrated polyethylene glycol solutions, ethanol, methanol, 2-propanol) and subsequently cross-linked with glutaraldehyde. Magnetic modification was successfully performed at low temperature in a freezer (−20 °C) using magnetic iron oxides nano- and microparticles prepared by microwave-assisted synthesis from ferrous sulfate. Magnetized cross-linked enzyme powders were stable at least for two months in water suspension without leakage of fixed magnetic particles. Operational stability of magnetically responsive enzymes during eight repeated reaction cycles was generally without loss of enzyme activity. Separation of magnetically modified cross-linked powdered enzymes from reaction mixtures was significantly simplified due to their magnetic properties. - Highlights: • Cross-linked enzyme powders were prepared in various liquid media. • Insoluble enzymes were magnetized using iron oxides particles. • Magnetic iron oxides particles were prepared by microwave-assisted synthesis. • Magnetic modification was performed under low (freezing) temperature. • Cross-linked powdered trypsin and lipase can be used repeatedly for reaction.

  3. Formulation of porous poly(lactic-co-glycolic acid) microparticles by electrospray deposition method for controlled drug release

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Shilei; Wang, Yazhou; Wang, Bochu, E-mail: wangbc2000@126.com; Deng, Jia; Zhu, Liancai; Cao, Yang

    2014-06-01

    In the present study, the electrospray deposition was successfully applied to prepare the porous poly(lactic-co-glycolic acid) (PLGA) microparticles by one-step processing. Metronidazole was selected as the model drug. The porous PLGA microparticles had high drug loading and low density, and the porous structure can be observed by scanning electron microscope (SEM) and transmission electron microscopy (TEM). The production time has been shortened considerably compared with that of the traditional multi-emulsion method. In addition, no chemical reaction occurred between the drug and polymer in the preparation of porous microparticles, and the crystal structure of drug did not change after entrapment into the porous microparticles. The porous microparticles showed a sustained release in the simulated gastric fluid, and the release followed non-Fickian or case II transport. Furthermore, porous microparticles showed a slight cytotoxicity in vitro. The results indicated that electrospray deposition is a good technique for preparation of porous microparticles, and the low-density porous PLGA microparticles has a potential for the development of gastroretentive systems or for pulmonary drug delivery. - Highlights: • The porous PLGA microparticles were successfully prepared by the electrospray deposition method at one step. • The porous microparticles had high loading capacity and low density. • The microparticle showed a sustained release in the simulated gastric liquid. • The microparticles showed a slight cytotoxicity in vitro.

  4. Formulation of porous poly(lactic-co-glycolic acid) microparticles by electrospray deposition method for controlled drug release

    International Nuclear Information System (INIS)

    Hao, Shilei; Wang, Yazhou; Wang, Bochu; Deng, Jia; Zhu, Liancai; Cao, Yang

    2014-01-01

    In the present study, the electrospray deposition was successfully applied to prepare the porous poly(lactic-co-glycolic acid) (PLGA) microparticles by one-step processing. Metronidazole was selected as the model drug. The porous PLGA microparticles had high drug loading and low density, and the porous structure can be observed by scanning electron microscope (SEM) and transmission electron microscopy (TEM). The production time has been shortened considerably compared with that of the traditional multi-emulsion method. In addition, no chemical reaction occurred between the drug and polymer in the preparation of porous microparticles, and the crystal structure of drug did not change after entrapment into the porous microparticles. The porous microparticles showed a sustained release in the simulated gastric fluid, and the release followed non-Fickian or case II transport. Furthermore, porous microparticles showed a slight cytotoxicity in vitro. The results indicated that electrospray deposition is a good technique for preparation of porous microparticles, and the low-density porous PLGA microparticles has a potential for the development of gastroretentive systems or for pulmonary drug delivery. - Highlights: • The porous PLGA microparticles were successfully prepared by the electrospray deposition method at one step. • The porous microparticles had high loading capacity and low density. • The microparticle showed a sustained release in the simulated gastric liquid. • The microparticles showed a slight cytotoxicity in vitro

  5. Vascular complications in diabetes: Microparticles and microparticle associated microRNAs as active players.

    Science.gov (United States)

    Alexandru, Nicoleta; Badila, Elisabeta; Weiss, Emma; Cochior, Daniel; Stępień, Ewa; Georgescu, Adriana

    2016-03-25

    The recognition of the importance of diabetes in vascular disease has greatly increased lately. Common risk factors for diabetes-related vascular disease include hyperglycemia, insulin resistance, dyslipidemia, inflammation, hypercoagulability, hypertension, and atherosclerosis. All of these factors contribute to the endothelial dysfunction which generates the diabetic complications, both macro and microvascular. Knowledge of diabetes-related vascular complications and of associated mechanisms it is becoming increasingly important for therapists. The discovery of microparticles (MPs) and their associated microRNAs (miRNAs) have opened new perspectives capturing the attention of basic and clinical scientists for their potential to become new therapeutic targets and clinical biomarkers. MPs known as submicron vesicles generated from membranes of apoptotic or activated cells into circulation have the ability to act as autocrine and paracrine effectors in cell-to-cell communication. They operate as biological vectors modulating the endothelial dysfunction, inflammation, coagulation, angiogenesis, thrombosis, subsequently contributing to the progression of macro and microvascular complications in diabetes. More recently, miRNAs have started to be actively investigated, leading to first exciting reports, which suggest their significant role in vascular physiology and disease. The contribution of MPs and also of their associated miRNAs to the development of vascular complications in diabetes was largely unexplored and undiscussed. In essence, with this review we bring light upon the understanding of impact diabetes has on vascular biology, and the significant role of MPs and MPs associated miRNAs as novel mediators, potential biomarkers and therapeutic targets in vascular complications in diabetes. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Evaluating tamsulosin hydrochloride-released microparticles prepared using single-step matrix coating.

    Science.gov (United States)

    Maeda, Atsushi; Shinoda, Tatsuki; Ito, Naoki; Baba, Keizo; Oku, Naoto; Mizumoto, Takao

    2011-04-15

    The objective of the present study was to determine the optimum composition for sustained-release of tamsulosin hydrochloride from microparticles intended for orally disintegrating tablets. Microparticles were prepared from an aqueous ethylcellulose dispersion (Aquacoa®), and an aqueous copolymer based on ethyl acrylate and methyl methacrylate dispersion (Eudragit®) NE30D), with microcrystalline cellulose as core particles with a fluidized bed coating process. Prepared microparticles were about 200 μm diameter and spherical. The microparticles were evaluated for in vitro drug release and in vivo absorption to assess bioequivalence in a commercial product, Harnal® pellets. The optimum ratio of Aquacoat® and Eudragit® NE30D in the matrix was 9:1. We observed similar drug release profiles in microparticles and Harnal® pellets. Higuchi model analysis of the in vitro drug release from microparticles was linear up to 80% release, typical of Fickian diffusion sustained-release profile. The in vivo absorption properties from microparticles were comparable to Harnal® pellets, and there was a linear relationship between in vitro drug release and in vivo drug release. In conclusion, this development produces microparticles in single-step coating, that provided a sustained-release of tamsulosin hydrochloride comparable to Harnal® pellets. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. Detection of circulating microparticles by flow cytometry: influence of centrifugation, filtration of buffer, and freezing.

    Science.gov (United States)

    Dey-Hazra, Emily; Hertel, Barbara; Kirsch, Torsten; Woywodt, Alexander; Lovric, Svjetlana; Haller, Hermann; Haubitz, Marion; Erdbruegger, Uta

    2010-12-06

    The clinical importance of microparticles resulting from vesiculation of platelets and other blood cells is increasingly recognized, although no standardized method exists for their measurement. Only a few studies have examined the analytical and preanalytical steps and variables affecting microparticle detection. We focused our analysis on microparticle detection by flow cytometry. The goal of our study was to analyze the effects of different centrifugation protocols looking at different durations of high and low centrifugation speeds. We also analyzed the effect of filtration of buffer and long-term freezing on microparticle quantification, as well as the role of Annexin V in the detection of microparticles. Absolute and platelet-derived microparticles were 10- to 15-fold higher using initial lower centrifugation speeds at 1500 × g compared with protocols using centrifugation speeds at 5000 × g (P centrifugation speeds. Filtration of buffer with a 0.2 μm filter reduced a significant amount of background noise. Storing samples for microparticle detection at -80°C decreased microparticle levels at days 28, 42, and 56 (P centrifugation speeds should be used to minimize contamination by smaller size platelets.

  8. Micro-particle filter made in SU-8 for biomedical applications

    DEFF Research Database (Denmark)

    Noeth, Nadine-Nicole; Keller, Stephan Urs; Fetz, Stefanie

    2009-01-01

    We have integrated a micro-particle filter in a polymer cantilever to filter micro-particles from a fluid while simultaneously measuring the amount of filtered particles. In a 3,8 mum thick SU-8 cantilever a filter was integrated with pore sizes between 3 and 30 mum. The chip was inserted in a mi...

  9. Nicotine-magnesium aluminum silicate microparticle surface modified with chitosan for mucosal delivery

    DEFF Research Database (Denmark)

    Kanjanakawinkul, Watchara; Rades, Thomas; Puttipipatkhachorn, Satit

    2013-01-01

    Magnesium aluminum silicate (MAS), a negatively charged clay, and nicotine (NCT), a basic drug, can interact electrostatically to form microparticles. Chitosan (CS) was used for the surface modification of the microparticles, and a lyophilization method was used to preserve the original particle...

  10. On-chip microparticle detection and sizing using a dual-wavelength waveguide laser

    NARCIS (Netherlands)

    Bernhardi, Edward H.; van der Werf, Kees O; Hollink, Anton J F; Worhoff, Kerstin; De Ridder, Rene M.; Subramaniam, Vinod; Pollnau, Markus

    2013-01-01

    An integrated intra-laser-cavity microparticle sensor based on a dual-phase-shift, dual-wavelength distributed-feedback channel waveguide laser in Al2O3:Yb3+ is presented. Real-time detection and accurate size measurement of single microparticles with diameters ranging between 1 μm and 20 μm are

  11. Intra-laser-cavity microparticle sensing with a dual-wavelength distributed-feedback laser

    NARCIS (Netherlands)

    Bernhardi, Edward H.; van der Werf, Kees O; Hollink, Anton J F; Wörhoff, Kerstin; de Ridder, René M; Subramaniam, Vinod; Pollnau, Markus

    An integrated intra-laser-cavity microparticle sensor based on a dual-wavelength distributed-feedback channel waveguide laser in ytterbium-doped amorphous aluminum oxide on a silicon substrate is demonstrated. Real-time detection and accurate size measurement of single micro-particles with diameters

  12. Effect of Formulation and Process Parameters on Chitosan Microparticles Prepared by an Emulsion Crosslinking Technique.

    Science.gov (United States)

    Rodriguez, Lidia B; Avalos, Abraham; Chiaia, Nicholas; Nadarajah, Arunan

    2017-05-01

    There are many studies about the synthesis of chitosan microparticles; however, most of them have very low production rate, have wide size distribution, are difficult to reproduce, and use harsh crosslinking agents. Uniform microparticles are necessary to obtain repeatable drug release behavior. The main focus of this investigation was to study the effect of the process and formulation parameters during the preparation of chitosan microparticles in order to produce particles with narrow size distribution. The technique evaluated during this study was emulsion crosslinking technique. Chitosan is a biocompatible and biodegradable material but lacks good mechanical properties; for that reason, chitosan was ionically crosslinked with sodium tripolyphosphate (TPP) at three different ratios (32, 64, and 100%). The model drug used was acetylsalicylic acid (ASA). During the preparation of the microparticles, chitosan was first mixed with ASA and then dispersed in oil containing an emulsifier. The evaporation of the solvents hardened the hydrophilic droplets forming microparticles with spherical shape. The process and formulation parameters were varied, and the microparticles were characterized by their morphology, particle size, drug loading efficiency, and drug release behavior. The higher drug loading efficiency was achieved by using 32% mass ratio of TPP to chitosan. The average microparticle size was 18.7 μm. The optimum formulation conditions to prepare uniform spherical microparticles were determined and represented by a region in a triangular phase diagram. The drug release analyses were evaluated in phosphate buffer solution at pH 7.4 and were mainly completed at 24 h.

  13. Improved positioning and detectability of microparticles in droplet microfluidics using two-dimensional acoustophoresis

    DEFF Research Database (Denmark)

    Ohlin, M.; Fornell, A.; Bruus, Henrik

    2017-01-01

    , by using acoustic actuation, (99.8 ± 0.4)% of all encapsulated microparticles can be detected compared to only (79.0 ± 5.1)% for unactuated operation. In our experiments we observed a strong ordering of the microparticles in distinct patterns within the droplet when using 2D acoustophoresis; to explain...

  14. On-chip microparticle detection and sizing using a dual-wavelength waveguide laser

    NARCIS (Netherlands)

    Bernhardi, Edward; van der Werf, Kees; Hollink, Anton; Worhoff, Kerstin; de Ridder, R.M.; Subramaniam, Vinod; Pollnau, Markus

    An integrated intra-laser-cavity microparticle sensor based on a dual-phase-shift, dual-wavelength distributed-feedback channel waveguide laser in ytterbium-doped aluminium oxide is presented. Single micro-particles with diameters ranging between 1 μm and 20 μm are detected.

  15. Distinct features of circulating microparticles and their relationship to clinical manifestations in systemic lupus erythematosus

    DEFF Research Database (Denmark)

    Nielsen, Christoffer T; Østergaard, Ole; Johnsen, Christina

    2011-01-01

    Characterization of the abundance, origin, and annexin V (AnxV)-binding capabilities of circulating microparticles (MPs) in SLE patients and healthy controls and to determine any associations with clinical parameters.......Characterization of the abundance, origin, and annexin V (AnxV)-binding capabilities of circulating microparticles (MPs) in SLE patients and healthy controls and to determine any associations with clinical parameters....

  16. Fabrication of starch-based microparticles by an emulsification-crosslinking method

    Science.gov (United States)

    Starch-based microparticles (MPs) fabricated by a water-in-water (w/w) emulsification-crosslinking method could be used as a controlled-release delivery vehicle for food bioactives. Due to the processing route without the use of toxic organic solvents, it is expected that these microparticles can be...

  17. Characterization of microparticles prepared by emulsion method from pectin and protein

    Science.gov (United States)

    In this study, pectin was extracted from apple peel and formulated into microparticles in combination with zein, an edible food protein. The physical, chemical, and structural properties of the resultant pectin structures were evaluated. The resultant microparticles were also examined in vitro for c...

  18. Concentration of nanoparticles and/or microparticles in flow conditions by dielectrophoresis

    DEFF Research Database (Denmark)

    2017-01-01

    A device for concentration of nanoparticles and/or microparticles in liquid flow conditions by dielectrophoresis is disclosed in this invention.......A device for concentration of nanoparticles and/or microparticles in liquid flow conditions by dielectrophoresis is disclosed in this invention....

  19. Proteomic Analysis of Serum Opsonins Impacting Biodistribution and Cellular Association of Porous Silicon Microparticles

    Directory of Open Access Journals (Sweden)

    Rita E. Serda

    2011-01-01

    Full Text Available Mass transport of drug delivery vehicles is guided by particle properties, such as size, shape, composition, and surface chemistry, as well as biomolecules and serum proteins that adsorb to the particle surface. In an attempt to identify serum proteins influencing cellular associations and biodistribution of intravascularly injected particles, we used two-dimensional gel electrophoresis and mass spectrometry to identify proteins eluted from the surface of cationic and anionic silicon microparticles. Cationic microparticles displayed a 25-fold greater abundance of Ig light variable chain, fibrinogen, and complement component 1 compared to their anionic counterparts. Anionic microparticles were found to accumulate in equal abundance in murine liver and spleen, whereas cationic microparticles showed preferential accumulation in the spleen. Immunohistochemistry supported macrophage uptake of both anionic and cationic microparticles in the liver, as well as evidence of association of cationic microparticles with hepatic endothelial cells. Furthermore, scanning electron micrographs supported cellular competition for cationic microparticles by endothelial cells and macrophages. Despite high macrophage content in the lungs and tumor, microparticle uptake by these cells was minimal, supporting differences in the repertoire of surface receptors expressed by tissue-specific macrophages. In summary, particle surface chemistry drives selective binding of serum components impacting cellular interactions and biodistribution.

  20. Magnetorheological fluids based on a hyperbranched polycarbosilane matrix and iron microparticles

    International Nuclear Information System (INIS)

    Vasiliev, V G; Buzin, M I; Papkov, V S; Muzafarov, A M; Kramarenko, E Yu; Sheremetyeva, N A; Turenko, D V; Klepikov, I A; Razumovskaya, I V

    2016-01-01

    Magnetorheological fluids (MFs) based on hyperbranched polycarbosilanes as a carrier medium and micron-sized carbonyl iron particles as filler have been synthesized for the first time. Their magnetorheological (MR) behavior has been studied in steady-state flow regime and under dynamic torsion oscillations on a commercial rheometer. At zero magnetic field, in spite of a rather high molecular mass, the hyperbranched polymers as well as their magnetic compositions with up to 72 mass% of magnetic filler demonstrate Newtonian behavior, and their viscosity considerably increases with magnetic filler content. In magnetic fields MFs show a huge MR response. Namely, in steady-state flow experiments a five orders of magnitude increase in viscosity was observed accompanied by magnetic-field-induced well-pronounced non-Newtonian behavior and a non-zero yield stress. Dynamic experiments demonstrate the transition from liquid-like to solid-like behavior of MFs with a large increase in both the storage and loss moduli under application of a magnetic field. In magnetic fields, the rheological behavior of the obtained MF resembles that of soft MR elastomers being mainly determined by the magnetic particle network formed due to magnetic interactions. In particular, like MR elastomers the MFs exhibit the Payne effect, i.e. dependence of the dynamic modulus on the strain amplitude. (paper)

  1. Ethanol oxidation on a nichrome-supported spherical platinum microparticle electrocatalyst prepared by electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhen-Hui; Li, Jing; Dong, Xiaoya; Wang, Dong; Chen, Tiwei; Qiao, Haiyan; Huang, Aiping [College of Chemistry and Environmental Science, Henan Key Laboratory for Environmental Pollution Control, Henan Normal University, Jianshe Road, Xinxiang 453007 (China)

    2008-11-15

    A novel electrode was rapidly prepared by depositing microparticle platinum onto a nichrome substrate in dilute chloroplatinic acid solution by cyclic voltammetry. The SEM results revealed that the deposits were composed of spherical Pt microparticles. Cyclic voltammetry and chronoamperometry were used for the characterization of the electrodes. Results of the electrochemical measurements showed that the spherical Pt microparticle electrodes retained the properties of metal platinum, increased the catalytic activity and promoted the electrocatalytic oxidation of ethanol. Moreover, the deposited Pt microparticles improved the electrochemical properties of the support material and reduced the dosage of noble metal platinum remarkably. The cost could be reduced dramatically by decreasing the contents of platinum. The spherical Pt microparticles deposited on the nichrome supports are likely a potential electrocatalyst for ethanol electrooxidation. (author)

  2. Spectroscopic evaluation of the effect of the microparticles on radiofrequency argon plasma

    International Nuclear Information System (INIS)

    Mitic, S; Pustylnik, M Y; Morfill, G E

    2009-01-01

    Axial distributions of 1s excited states of argon were measured in a radiofrequency (RF) discharge by a self-absorption method. Experiments were performed in the PK-3+ chamber, designed for microgravity experiments in complex (dusty) plasmas on board the International Space Station. A correction of a standard self-absorption method for the extinction of the light by the levitating microparticles is proposed. Distributions, measured at the same discharge conditions in a microparticle-free discharge and a discharge containing a cloud of levitating microparticles, revealed the non-local influence of the microparticle cloud on the discharge plasma. The most probable cause of this influence is the disturbance of the ionization balance by the levitating microparticles.

  3. Physicochemical characteristics of uranium microparticles collected at nuclear fuel cycle plants

    International Nuclear Information System (INIS)

    Kaurov, G.; Stebelkov, V.; Kolesnikov, O.; Frolov, D.

    2001-01-01

    Any industrial process is accompanied by appearance of some quantity of microparticles of processed matter in the environment in immediate proximity to the manufacturing object. These particles can be transferred in atmosphere and can be collected at some distances from the plant. The determination of characteristics of industrial dust microparticles at nuclear fuel cycle plants (form, size, structure of surface, elemental composition, isotopic composition, presence of fission products, presence of activation products) in conjunction with the ability to connect these characteristics with certain nuclear manufacturing processes can become the main technical method of detecting of undeclared nuclear activity. Systematization of the experimental data on morphology, elemental and isotopic composition of uranium microparticles, collected at nuclear fuel cycle plants, is given. The purpose of this work is to establish the relationship between morphological characteristics of uranium dust microparticles and types of nuclear manufacture and to define the reference attributes of the most informative microparticles

  4. Microparticle injection effects on microwave transmission through an overly dense plasma layer

    Energy Technology Data Exchange (ETDEWEB)

    Gillman, Eric D., E-mail: eric.gillman@nrl.navy.mil; Amatucci, W. E. [Naval Research Laboratory, Washington, DC 20375 (United States); Williams, Jeremiah [Wittenberg University, Springfield, Ohio 45501 (United States); Compton, C. S. [Sotera Defense Solutions, Herndon, Virginia 20171 (United States)

    2015-04-15

    Microparticles injected into a plasma have been shown to deplete the free electron population as electrons are collected through the process of microparticles charging to the plasma floating potential. However, these charged microparticles can also act to scatter electromagnetic signals. These experiments investigate microwave penetration through a previously impenetrable overly dense plasma layer as microparticles are injected and the physical phenomena associated with the competing processes that occur due to electron depletion and microwave scattering. The timescales for when each of these competing processes dominates is analyzed in detail. It was found that while both processes play a significant and dominant role at different times, ultimately, transmission through this impenetrable plasma layer can be significantly increased with microparticle injection.

  5. Detection of microparticles from human red blood cells by multiparametric flow cytometry

    Science.gov (United States)

    Grisendi, Giulia; Finetti, Elena; Manganaro, Daniele; Cordova, Nicoletta; Montagnani, Giuliano; Spano, Carlotta; Prapa, Malvina; Guarneri, Valentina; Otsuru, Satoru; Horwitz, Edwin M.; Mari, Giorgio; Dominici, Massimo

    2015-01-01

    Background During storage, red blood cells (RBC) undergo chemical and biochemical changes referred to as “storage lesions”. These events determine the loss of RBC integrity, resulting in lysis and release of microparticles. There is growing evidence of the clinical importance of microparticles and their role in blood transfusion-related side effects and pathogen transmission. Flow cytometry is currently one of the most common techniques used to quantify and characterise microparticles. Here we propose multiparametric staining to monitor and quantify the dynamic release of microparticles by stored human RBC. Material and methods RBC units (n=10) were stored under blood bank conditions for up to 42 days. Samples were tested at different time points to detect microparticles and determine the haemolysis rate (HR%). Microparticles were identified by flow cytometry combining carboxyfluorescein diacetate succinimidyl ester (CFSE) dye, annexin V and anti-glycophorin A antibody. Results We demonstrated that CFSE can be successfully used to label closed vesicles with an intact membrane. The combination of CFSE and glycophorin A antibody was effective for monitoring and quantifying the dynamic release of microparticles from RBC during storage. Double staining with CFSE/glycophorin A was a more precise approach, increasing vesicle detection up to 4.7-fold vs the use of glycophorin A/annexin V alone. Moreover, at all the time points tested, we found a robust correlation (R=0.625; p=0.0001) between HR% and number of microparticles detected. Discussion Multiparametric staining, based on a combination of CFSE, glycophorin A antibody and annexin V, was able to detect, characterise and monitor the release of microparticles from RBC units during storage, providing a sensitive approach to labelling and identifying microparticles for transfusion medicine and, more broadly, for cell-based therapies. PMID:25369588

  6. Phospholipid Binding Protein C Inhibitor (PCI) Is Present on Microparticles Generated In Vitro and In Vivo

    Science.gov (United States)

    Einfinger, Katrin; Badrnya, Sigrun; Furtmüller, Margareta; Handschuh, Daniela; Lindner, Herbert; Geiger, Margarethe

    2015-01-01

    Protein C inhibitor is a secreted, non-specific serine protease inhibitor with broad protease reactivity. It binds glycosaminoglycans and anionic phospholipids, which can modulate its activity. Anionic phospholipids, such as phosphatidylserine are normally localized to the inner leaflet of the plasma membrane, but are exposed on activated and apoptotic cells and on plasma membrane-derived microparticles. In this report we show by flow cytometry that microparticles derived from cultured cells and activated platelets incorporated protein C inhibitor during membrane blebbing. Moreover, protein C inhibitor is present in/on microparticles circulating in normal human plasma as judged from Western blots, ELISAs, flow cytometry, and mass spectrometry. These plasma microparticles are mainly derived from megakaryocytes. They seem to be saturated with protein C inhibitor, since they do not bind added fluorescence-labeled protein C inhibitor. Heparin partially removed microparticle-bound protein C inhibitor, supporting our assumption that protein C inhibitor is bound via phospholipids. To assess the biological role of microparticle-bound protein C inhibitor we performed protease inhibition assays and co-precipitated putative binding partners on microparticles with anti-protein C inhibitor IgG. As judged from amidolytic assays microparticle-bound protein C inhibitor did not inhibit activated protein C or thrombin, nor did microparticles modulate the activity of exogenous protein C inhibitor. Among the proteins co-precipitating with protein C inhibitor, complement factors, especially complement factor 3, were most striking. Taken together, our data do not support a major role of microparticle-associated protein C inhibitor in coagulation, but rather suggest an interaction with proteins of the complement system present on these phospholipid vesicles. PMID:26580551

  7. Carboxylated mesoporous carbon microparticles as new approach to improve the oral bioavailability of poorly water-soluble carvedilol.

    Science.gov (United States)

    Zhang, Yanzhuo; Zhi, Zhizhuang; Li, Xue; Gao, Jian; Song, Yaling

    2013-09-15

    The main objective of this study was to develop carboxylated ordered mesoporous carbon microparticles (c-MCMs) loaded with a poorly water-soluble drug, intended to be orally administered, able to enhance the drug loading capacity and improve the oral bioavailability. A model drug, carvedilol (CAR), was loaded onto c-MCMs via a procedure involving a combination of adsorption equilibrium and solvent evaporation. The physicochemical properties of the drug-loaded composites were systematically studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption, powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and HPLC. It was found that c-MCM has a high drug loading level up to 41.6%, and higher than that of the mesoporous silica template. Incorporation of CAR in both drug carriers enhanced the solubility and dissolution rate of the drug, compared to the pure crystalline drug. After loading CAR into c-MCMs, its oral bioavailability was compared with the marketed product in dogs. The results showed that the bioavailability of CAR was improved 179.3% compared with that of the commercial product when c-MCM was used as the drug carrier. We believe that the present study will help in the design of oral drug delivery systems for enhanced oral bioavailability of poorly water-soluble drugs. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. 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.

  9. Galectin-3 binding protein links circulating microparticles with electron dense glomerular deposits in lupus nephritis.

    Science.gov (United States)

    Nielsen, C T; Østergaard, O; Rekvig, O P; Sturfelt, G; Jacobsen, S; Heegaard, N H H

    2015-10-01

    A high level of galectin-3-binding protein (G3BP) appears to distinguish circulating cell-derived microparticles in systemic lupus erythematosus (SLE). The aim of this study is to characterize the population of G3BP-positive microparticles from SLE patients compared to healthy controls, explore putative clinical correlates, and examine if G3BP is present in immune complex deposits in kidney biopsies from patients with lupus nephritis. Numbers of annexin V-binding and G3BP-exposing plasma microparticles from 56 SLE patients and 36 healthy controls were determined by flow cytometry. Quantitation of microparticle-associated G3BP, C1q and immunoglobulins was obtained by liquid chromatography tandem mass spectrometry (LC-MS/MS). Correlations between microparticle-G3BP data and clinical parameters were analyzed. Co-localization of G3BP with in vivo-bound IgG was examined in kidney biopsies from one non-SLE control and from patients with class IV (n = 2) and class V (n = 1) lupus nephritis using co-localization immune electron microscopy. Microparticle-G3BP, microparticle-C1q and microparticle-immunoglobulins were significantly (P microparticle populations could be discerned by flow cytometry, including two subpopulations that were significantly increased in SLE samples (P = 0.01 and P = 0.0002, respectively). No associations of G3BP-positive microparticles with clinical manifestations or disease activity were found. Immune electron microscopy showed co-localization of G3BP with in vivo-bound IgG in glomerular electron dense immune complex deposits in all lupus nephritis biopsies. Both circulating microparticle-G3BP numbers as well as G3BP expression are increased in SLE patients corroborating G3BP being a feature of SLE microparticles. By demonstrating G3BP co-localized with deposited immune complexes in lupus nephritis, the study supports cell-derived microparticles as a major autoantigen source and provides a new understanding of the origin of

  10. Live cell refractometry based on non-SPR microparticle sensor.

    Science.gov (United States)

    Liu, Chang; Chen, David D Y; Yu, Lirong; Luo, Yong

    2013-06-01

    Unlike the nanoparticles with surface plasmon resonance, the optical response of polystyrene microparticles (PSMPs) is insensitive to the chemical components of the surrounding medium under the wavelength-dependent differential interference contrast microscopy. This fact is exploited for the measurement of the refractive index of cytoplasm in this study. PSMPs of 400 nm in diameter were loaded into the cell to contact cytoplasm seamlessly, and the refractive index information of cytoplasm could be extracted by differential interference contrast microscopy operated at 420 nm illumination wavelength through the contrast analysis of PSMPs images. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Studies of microparticles in patients with the antiphospholipid syndrome (APS).

    Science.gov (United States)

    Vikerfors, A; Mobarrez, F; Bremme, K; Holmström, M; Ågren, A; Eelde, A; Bruzelius, M; Antovic, A; Wallén, H; Svenungsson, E

    2012-06-01

    To study circulating platelet, monocyte and endothelial microparticles (PMPs, MMPs and EMPs) in patients with antiphospholipid syndrome (APS) in comparison with healthy controls. Fifty-two patients with APS and 52 healthy controls were investigated. MPs were measured on a flow cytometer (Beckman Gallios) and defined as particles sized APS patients versus controls (p APS patients. We observed a high number of EMPs expressing TF in APS patients. The numbers of MMPs and total EMPs were also higher as compared with healthy controls but in contrast to previous reports, the number of PMPs did not differ between groups.

  12. Size-controlled fabrication of zein nano/microparticles by modified anti-solvent precipitation with/without sodium caseinate

    Directory of Open Access Journals (Sweden)

    Li F

    2017-11-01

    Full Text Available Feng Li,1 Yan Chen,1,2 Shubo Liu,1 Jian Qi,1 Weiying Wang,1 Chenhua Wang,1 Ruiyue Zhong,1 Zhijun Chen,1 Xiaoming Li,1 Yuanzhou Guan,1 Wei Kong,1,2 Yong Zhang1,2 1National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 2Key Laboratory for Molecular Enzymology and Engineering, the Ministry of Education, School of Life Sciences, Jilin University, Changchun, China Abstract: Zein-based nano/microparticles have been demonstrated to be promising carrier systems for both the food industry and biomedical applications. However, the fabrication of size-controlled zein particles has been a challenging issue. In this study, a modified anti-solvent precipitation method was developed, and the effects of various factors, such as mixing method, solvent/anti-solvent ratio, temperature, zein concentrations and the presence of sodium caseinate (SC on properties of zein particles were investigated. Evidence is presented that, among the previously mentioned factors, the mixing method, especially mixing rate, could be used as an effective parameter to control the size of zein particles without changing other parameters. Moreover, through fine-tuning the mixing rate together with zein concentration, particles with sizes ranging from nanometers to micrometers and low polydispersity index values could be easily obtained. Based on the size-controlled fabrication method, SC-coated zein nanoparticles could also be obtained in a size-controlled manner by incubation of the coating material with the already-formed zein particles. The resultant nanoparticles showed better performance in both drug loading and controlled release, compared with zein/SC hybrid nanoparticles fabricated by adding aqueous ethanol solution to SC solution. The possible mechanisms of the nanoprecipitation process and self-assembly formation of these nanoparticles are discussed. Keywords: zein, phase separation, microparticle, nanoparticle, encapsulation

  13. Magnetic properties of diluted magnetic semiconductors

    NARCIS (Netherlands)

    Jonge, de W.J.M.; Swagten, H.J.M.

    1991-01-01

    A review will be given of the magnetic characteristics of diluted magnetic semiconductors and the relation with the driving exchange mechanisms. II–VI as well as IV–VI compounds will be considered. The relevance of the long-range interaction and the role of the carrier concentration will be

  14. Microparticle content of platelet concentrates is predicted by donor microparticles and is altered by production methods and stress.

    Science.gov (United States)

    Maurer-Spurej, Elisabeth; Larsen, Rune; Labrie, Audrey; Heaton, Andrew; Chipperfield, Kate

    2016-08-01

    In circulation, shedding of microparticles from a variety of viable cells can be triggered by pathological activation of inflammatory processes, by activation of coagulation or complement systems, or by physical stress. Elevated microparticle content (MPC) in donor blood might therefore indicate a clinical condition of the donor which, upon transfusion, might affect the recipient. In blood products, elevated MPC might also represent product stress. Surprisingly, the MPC in blood collected from normal blood donors is highly variable, which raises the question whether donor microparticles are present in-vivo and transfer into the final blood component, and how production methods and post-production processing might affect the MPC. We measured MPC using ThromboLUX in (a) platelet-rich plasma (PRP) of 54 apheresis donors and the corresponding apheresis products, (b) 651 apheresis and 646 pooled platelet concentrates (PCs) with plasma and 414 apheresis PCs in platelet additive solution (PAS), and (c) apheresis PCs before and after transportation, gamma irradiation, and pathogen inactivation (N = 8, 7, and 12 respectively). ThromboLUX-measured MPC in donor PRP and their corresponding apheresis PC samples were highly correlated (r = 0.82, P = .001). The average MPC in pooled PC was slightly lower than that in apheresis PC and substantially lower in apheresis PC stored with PAS rather than plasma. Mirasol Pathogen Reduction treatment significantly increased MPC with age. Thus, MPC measured in donor samples might be a useful predictor of product stability, especially if post-production processes are necessary. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Preparation and evaluation of microparticles from thiolated polymers via air jet milling.

    Science.gov (United States)

    Hoyer, Herbert; Schlocker, Wolfgang; Krum, Kafedjiiski; Bernkop-Schnürch, Andreas

    2008-06-01

    Microparticles were formulated by incorporation of the model protein horseradish peroxidase in (thiolated) chitosan and (thiolated) poly(acrylic acid) via co-precipitation. Dried protein/polymer complexes were ground with an air jet mill and resulting particles were evaluated regarding size distribution, shape, zeta potential, drug load, protein activity, release pattern, swelling behaviour and cytotoxicity. The mean particle size distribution was 0.5-12 microm. Non-porous microparticles with a smooth surface were prepared. Microparticles from (thiolated) chitosan had a positive charge whereas microparticles from (thiolated) poly(acrylic acid) were negatively charged. The maximum protein load for microparticles based on chitosan, chitosan-glutathione (Ch-GSH), poly(acrylic acid) (PAA) and for poly(acrylic acid)-glutathione (PAA-GSH) was 7+/-1%, 11+/-2%, 4+/-0.2% and 7+/-2%, respectively. The release profile of all microparticles followed a first order release kinetic. Chitosan (0.5mg), Ch-GSH, PAA and PAA-GSH particles showed a 31.4-, 13.8-, 54.2- and a 42.2-fold increase in weight, respectively. No significant cytotoxicity could be found. Thiolated microparticles prepared by jet milling technique were shown to be stable and to have controlled drug release characteristics. After further optimizations the preparation method described here might be a useful tool for the production of protein loaded drug delivery systems.

  16. Novel hierarchical microparticles super-assembled from nanoparticles with the induction of casein micelles

    Science.gov (United States)

    Xiong, Xiaopeng; Duan, Jiangjiang; Wang, Yong; Yu, Zhaoju

    2013-08-01

    We have demonstrated a solution-based synthesis of novel waxberry-like hierarchical ZnO microparticles in the presence casein micelles under mild conditions. The microstructures of the sub-micrometer-sized hierarchical microparticles were characterized, and the synthesis conditions were optimized. The formation mechanism of the hierarchical microparticle was analyzed through control experiments. The hierarchical ZnO microparticles are found to be super-assemblies of 30-70 nm ZnO nanoparticles, which are thought to be based on casein micelle induction followed by Ostwald ripening. In the same manner, copper-based hierarchical microparticles with a similar morphology have also been successfully synthesized. By controlling the synthetic time or temperature, solid or hollow microparticles can be fabricated. The narrowly distributed ZnO microparticles have a high specific surface area, exhibiting great potential application in fields such as photocatalytic and energy conversion. Our findings may meanwhile open a new bottom-up strategy in order to construct structurally sophisticated nanomaterials.

  17. Novel hierarchical microparticles super-assembled from nanoparticles with the induction of casein micelles

    International Nuclear Information System (INIS)

    Xiong, Xiaopeng; Duan, Jiangjiang; Wang, Yong; Yu, Zhaoju

    2013-01-01

    We have demonstrated a solution-based synthesis of novel waxberry-like hierarchical ZnO microparticles in the presence casein micelles under mild conditions. The microstructures of the sub-micrometer-sized hierarchical microparticles were characterized, and the synthesis conditions were optimized. The formation mechanism of the hierarchical microparticle was analyzed through control experiments. The hierarchical ZnO microparticles are found to be super-assemblies of 30–70 nm ZnO nanoparticles, which are thought to be based on casein micelle induction followed by Ostwald ripening. In the same manner, copper-based hierarchical microparticles with a similar morphology have also been successfully synthesized. By controlling the synthetic time or temperature, solid or hollow microparticles can be fabricated. The narrowly distributed ZnO microparticles have a high specific surface area, exhibiting great potential application in fields such as photocatalytic and energy conversion. Our findings may meanwhile open a new bottom-up strategy in order to construct structurally sophisticated nanomaterials

  18. Incorporation of essential oil in alginate microparticles by multiple emulsion/ionic gelation process.

    Science.gov (United States)

    Hosseini, Seyede Marzieh; Hosseini, Hedayat; Mohammadifar, Mohammad Amin; Mortazavian, Amir Mohammad; Mohammadi, Abdorreza; Khosravi-Darani, Kianoosh; Shojaee-Aliabadi, Saeedeh; Dehghan, Solmaz; Khaksar, Ramin

    2013-11-01

    In this study, an o/w/o multiple emulsion/ionic gelation method was developed for production of alginate microparticles loaded with Satureja hortensis essential oil (SEO). It was found that the essential oil concentration has significant influence on encapsulation efficiency (EE), loading capacity (LC) and size of microparticles. The values of EE, LC and particle mean diameter were about 52-66%, 20-26%, and 47-117 μm, respectively, when the initial SEO content was 1-3% (v/v) .The essential oil-loaded microparticles were porous, as displayed by scanning electron micrograph. The presence of SEO in alginate microparticles was confirmed by Fourier transform-infrared (FT-IR) spectroscopy and differential scanning calorimetry (DSC) analyses. SEO-loaded microparticles showed good antioxidant (with DPPH radical scavenging activity of 40.7-73.5%) and antibacterial properties; this effect was greatly improved when the concentration of SEO was 3% (v/v). S. aureus was found to be the most sensitive bacterium to SEO and showed a highest inhibition zone of 304.37 mm(2) in the microparticles incorporated with 3% (v/v) SEO. In vitro release studies showed an initial burst release and followed by a slow release. In addition, the release of SEO from the microparticles followed Fickian diffusion with acceptable release. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Novel hierarchical microparticles super-assembled from nanoparticles with the induction of casein micelles

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Xiaopeng, E-mail: xpxiong@xmu.edu.cn; Duan, Jiangjiang; Wang, Yong; Yu, Zhaoju [Xiamen University, Department of Materials Science and Engineering, College of Materials (China)

    2013-08-15

    We have demonstrated a solution-based synthesis of novel waxberry-like hierarchical ZnO microparticles in the presence casein micelles under mild conditions. The microstructures of the sub-micrometer-sized hierarchical microparticles were characterized, and the synthesis conditions were optimized. The formation mechanism of the hierarchical microparticle was analyzed through control experiments. The hierarchical ZnO microparticles are found to be super-assemblies of 30-70 nm ZnO nanoparticles, which are thought to be based on casein micelle induction followed by Ostwald ripening. In the same manner, copper-based hierarchical microparticles with a similar morphology have also been successfully synthesized. By controlling the synthetic time or temperature, solid or hollow microparticles can be fabricated. The narrowly distributed ZnO microparticles have a high specific surface area, exhibiting great potential application in fields such as photocatalytic and energy conversion. Our findings may meanwhile open a new bottom-up strategy in order to construct structurally sophisticated nanomaterials.

  20. Heat exchange between a microparticle and plasma. Contribution of charge transfer processes

    International Nuclear Information System (INIS)

    Uglov, A.A.; Gnedovets, A.G.

    1983-01-01

    Heat- and mass-transfer in interaction of a microparticle with a dense plasma have been considered analytically. At that, calculation methods developed as applied to probe diagnostics of slightly ionized plasma are also used in the case of relatively high degrees of ionization, at which heat flows of plasma charged particles Qe and Qi become comparable with molecular ones. High efficiency of energy transfer during electron and ion collisions with a microparticle is due to the following: 1) effective cross section of ion collision with a microparticle, which acquires in a quasineutral plasma the potential phisub(f) < 0, surpasses the geometric one; the maximum contribution of electron and ion constituent is achieved when the cross section ion collisions with a microparticle is linearly connected with its potential, 2) with a charged microparticle electrons from distribution function ''tail'' collide, their energy exceeds potential barrier near the surface and, consequently, the mean heat energy; 3) besides the energy of a microparticle thermal movement during electron recombination and ion neutralization on its surface the heat Qsub(e) and Qsub(i), which considerably exceed the heat of molecular adsorption and mean heat energy of plasma particles at kT approximately 1 eV, are transmitted to the microparticle

  1. Circulating erythrocyte-derived microparticles are associated with coagulation activation in sickle cell disease

    Science.gov (United States)

    van Beers, Eduard J.; Schaap, Marianne C.L.; Berckmans, René J.; Nieuwland, Rienk; Sturk, Augueste; van Doormaal, Frederiek F.; Meijers, Joost C.M.; Biemond, Bart J.

    2009-01-01

    Background Sickle cell disease is characterized by a hypercoagulable state as a result of multiple factors, including chronic hemolysis and circulating cell-derived microparticles. There is still no consensus on the cellular origin of such microparticles and the exact mechanism by which they may enhance coagulation activation in sickle cell disease. Design and Methods In the present study, we analyzed the origin of circulating microparticles and their procoagulant phenotype during painful crises and steady state in 25 consecutive patients with sickle cell disease. Results The majority of microparticles originated from platelets (GPIIIa,CD61) and erythrocytes (glycophorin A,CD235), and their numbers did not differ significantly between crisis and steady state. Erythrocyte-derived microparticles strongly correlated with plasma levels of markers of hemolysis, i.e. hemoglobin (r=−0.58, pmicroparticles (r=0.63, p0.05). The extent of factor XI inhibition was associated with erythrocyte-derived microparticles (r=0.50, p=0.023). Conclusions We conclude that the procoagulant state in sickle cell disease is partially explained by the factor XI-dependent procoagulant properties of circulating erythrocyte-derived microparticles. PMID:19815831

  2. Proteomic Analysis of Serum Opsonins Impacting Biodistribution and Cellular Association of Porous Silicon Microparticles

    Science.gov (United States)

    Serda, Rita E.; Blanco, Elvin; Mack, Aaron; Stafford, Susan J.; Amra, Sarah; Li, Qingpo; van de Ven, Anne L.; Tanaka, Takemi; Torchilin, Vladimir P.; Wiktorowicz, John E.; Ferrari, Mauro

    2014-01-01

    Mass transport of drug delivery vehicles is guided by particle properties, such as shape, composition and surface chemistry, as well as biomolecules and serum proteins that adsorb to the particle surface. In an attempt to identify serum proteins influencing cellular associations and biodistribution of intravascularly injected particles, we used two dimensional gel electrophoresis and mass spectrometry to identify proteins eluted from the surface of cationic and anionic silicon microparticles. Cationic microparticles displayed a 25-fold greater abundance of Ig light chain variable region, fibrinogen, and complement component 1 compared to their anionic counterparts. The anionic-surface favored equal accumulation of microparticles in the liver and spleen, while cationic-surfaces favored preferential accumulation in the spleen. Immunohistochemistry supported macrophage internalization of both anionic and cationic silicon microparticles in the liver, as well as evidence of association of cationic microparticles with hepatic endothelial cells. Furthermore, scanning electron micrographs supported cellular competition for cationic microparticles by endothelial cells and macrophages. Despite high macrophage content in the lungs and tumor, microparticle uptake by these cells was minimal, supporting differences in the repertoire of surface receptors expressed by tissue-specific macrophages. In summary, particle surface chemistry drives selective binding of serum components impacting cellular interactions and biodistribution. PMID:21303614

  3. Porous Polystyrene Monoliths and Microparticles Prepared from Core Cross-linked Star (CCS) Polymers-Stabilized Emulsions.

    Science.gov (United States)

    Chen, Qijing; Shi, Ting; Han, Fei; Li, Zihan; Lin, Chao; Zhao, Peng

    2017-08-17

    A hydrophobic CCS polymer of poly(benzyl methacrylate) (PBzMA) was prepared in toluene by reversible addition-fragmentation chain transfer (RAFT)-mediated dispersion polymerization. The CCS polymer, with poly(benzyl methacrylate) as the arm and crosslinked N, N'-bis(acryloyl)cystamine (BAC) as the core, was confirmed by characterization with gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy. Three kinds of oils (toluene, anisole and styrene) were chosen to study the emulsification properties of PBzMA CCS polymer. The oils can be emulsified by CCS polymer to form water-in-oil (w/o) emulsions. Moreover, w/o high internal phase emulsions (HIPEs) can be obtained with the increase of toluene and styrene volume fractions from 75% to 80%. Porous polystyrene monolith and microparticles were prepared from the emulsion templates and characterized by the scanning electronic microscopy (SEM). With the internal phase volume fraction increased, open-pore porous monolith was obtained.

  4. The Young's Modulus, Fracture Stress, and Fracture Strain of Gellan Hydrogels Filled with Whey Protein Microparticles.

    Science.gov (United States)

    Lam, Cherry Wing Yu; Ikeda, Shinya

    2017-05-01

    Texture modifying abilities of whey protein microparticles are expected to be dependent on pH during heat-induced aggregation of whey protein in the microparticulation process. Therefore, whey protein microparticles were prepared at either pH 5.5 or 6.8 and their effects on small and large deformation properties of gellan gels containing whey protein microparticles as fillers were investigated. The majority of whey protein microparticles had diameters around 2 μm. Atomic force microscopy images showed that whey protein microparticles prepared at pH 6.8 partially collapsed and flatted by air-drying, while those prepared at pH 5.5 did not. The Young's modulus of filled gels adjusted to pH 5.5 decreased by the addition of whey protein microparticles, while those of filled gels adjusted to pH 6.8 increased with increasing volume fraction of filler particles. These results suggest that filler particles were weakly bonded to gel matrices at pH 5.5 but strongly at pH 6.8. Whey protein microparticles prepared at pH 5.5 showed more enhanced increases in the Young's modulus than those prepared at pH 6.8 at volume fractions between 0.2 and 0.4, indicating that microparticles prepared at pH 5.5 were mechanically stronger. The fracture stress of filled gels showed trends somewhat similar to those of the Young's modulus, while their fracture strains decreased by the addition of whey protein microparticles in all examined conditions, indicating that the primary effect of these filler particles was to enhance the brittleness of filled gels. © 2017 Institute of Food Technologists®.

  5. Microparticle Shedding from Neural Progenitor Cells and Vascular Compartment Cells Is Increased in Ischemic Stroke.

    Science.gov (United States)

    Chiva-Blanch, Gemma; Suades, Rosa; Crespo, Javier; Peña, Esther; Padró, Teresa; Jiménez-Xarrié, Elena; Martí-Fàbregas, Joan; Badimon, Lina

    2016-01-01

    Ischemic stroke has shown to induce platelet and endothelial microparticle shedding, but whether stroke induces microparticle shedding from additional blood and vascular compartment cells is unclear. Neural precursor cells have been shown to replace dying neurons at sites of brain injury; however, if neural precursor cell activation is associated to microparticle shedding, and whether this activation is maintained at long term and associates to stroke type and severity remains unknown. We analyzed neural precursor cells and blood and vascular compartment cells microparticle shedding after an acute ischemic stroke. Forty-four patients were included in the study within the first 48h after the onset of stroke. The cerebral lesion size was evaluated at 3-7 days of the stroke. Circulating microparticles from neural precursor cells and blood and vascular compartment cells (platelets, endothelial cells, erythrocytes, leukocytes, lymphocytes, monocytes and smooth muscle cells) were analyzed by flow cytometry at the onset of stroke and at 7 and 90 days. Forty-four age-matched high cardiovascular risk subjects without documented vascular disease were used as controls. Compared to high cardiovascular risk controls, patients showed higher number of neural precursor cell- and all blood and vascular compartment cell-derived microparticles at the onset of stroke, and after 7 and 90 days. At 90 days, neural precursor cell-derived microparticles decreased and smooth muscle cell-derived microparticles increased compared to levels at the onset of stroke, but only in those patients with the highest stroke-induced cerebral lesions. Stroke increases blood and vascular compartment cell and neural precursor cell microparticle shedding, an effect that is chronically maintained up to 90 days after the ischemic event. These results show that stroke induces a generalized blood and vascular cell activation and the initiation of neuronal cell repair process after stroke. Larger cerebral lesions

  6. Microparticle Shedding from Neural Progenitor Cells and Vascular Compartment Cells Is Increased in Ischemic Stroke.

    Directory of Open Access Journals (Sweden)

    Gemma Chiva-Blanch

    Full Text Available Ischemic stroke has shown to induce platelet and endothelial microparticle shedding, but whether stroke induces microparticle shedding from additional blood and vascular compartment cells is unclear. Neural precursor cells have been shown to replace dying neurons at sites of brain injury; however, if neural precursor cell activation is associated to microparticle shedding, and whether this activation is maintained at long term and associates to stroke type and severity remains unknown. We analyzed neural precursor cells and blood and vascular compartment cells microparticle shedding after an acute ischemic stroke.Forty-four patients were included in the study within the first 48h after the onset of stroke. The cerebral lesion size was evaluated at 3-7 days of the stroke. Circulating microparticles from neural precursor cells and blood and vascular compartment cells (platelets, endothelial cells, erythrocytes, leukocytes, lymphocytes, monocytes and smooth muscle cells were analyzed by flow cytometry at the onset of stroke and at 7 and 90 days. Forty-four age-matched high cardiovascular risk subjects without documented vascular disease were used as controls.Compared to high cardiovascular risk controls, patients showed higher number of neural precursor cell- and all blood and vascular compartment cell-derived microparticles at the onset of stroke, and after 7 and 90 days. At 90 days, neural precursor cell-derived microparticles decreased and smooth muscle cell-derived microparticles increased compared to levels at the onset of stroke, but only in those patients with the highest stroke-induced cerebral lesions.Stroke increases blood and vascular compartment cell and neural precursor cell microparticle shedding, an effect that is chronically maintained up to 90 days after the ischemic event. These results show that stroke induces a generalized blood and vascular cell activation and the initiation of neuronal cell repair process after stroke. Larger

  7. Liver cell-derived microparticles activate hedgehog signaling and alter gene expression in hepatic endothelial cells.

    Science.gov (United States)

    Witek, Rafal P; Yang, Liu; Liu, Renshui; Jung, Youngmi; Omenetti, Alessia; Syn, Wing-Kin; Choi, Steve S; Cheong, Yeiwon; Fearing, Caitlin M; Agboola, Kolade M; Chen, Wei; Diehl, Anna Mae

    2009-01-01

    Angiogenesis contributes to vascular remodeling during cirrhosis. In cirrhotic livers, cholangiocytes, and myofibroblastic hepatic stellate cells (MF-HSC) produce Hedgehog (Hh) ligands. During embryogenesis Hh ligands are released from ligand-producing cells in microparticles and activate Hh signaling in endothelial cells. We studied whether adult liver cell-derived microparticles contain Hh ligands that alter hepatic sinusoidal endothelial cells (SEC). MF-HSC and cholangiocytes were exposed to platelet-derived growth factor to induce Hh ligands; microparticles were isolated from medium, analyzed by transmission electron microscopy and immunoblots, and applied to Hh-reporter-containing cells. Microparticles were obtained from serum and bile of rats after bile duct ligation (BDL) or sham surgery and applied to normal primary liver SEC with or without cyclopamine, an Hh signaling inhibitor. Effects on SEC gene expression were evaluated by quantitative reverse-transcription polymerase chain reaction and immunoblotting. Hh target gene expression and SEC activation markers were compared in primary SEC and in liver sections from healthy and BDL rats. Platelet-derived growth factor-treated MF-HSC and cholangiocytes released exosome-enriched microparticles containing biologically-active Hh ligands. BDL increased release of Hh-containing exosome-enriched microparticles into plasma and bile. Transmission electron microscopy and immunoblots revealed similarities among microparticles from all sources; all microparticles induced similar Hh-dependent changes in SEC gene expression. SEC from healthy livers did not express Hh target genes or activation markers, but both were up-regulated in SEC after BDL. Hh-containing exosome-enriched microparticles released from liver cells alter hepatic SEC gene expression, suggesting a novel mechanism for cirrhotic vasculopathy.

  8. In vitro assessment of biopolymer-modified porous silicon microparticles for wound healing applications.

    Science.gov (United States)

    Mori, Michela; Almeida, Patrick V; Cola, Michela; Anselmi, Giulia; Mäkilä, Ermei; Correia, Alexandra; Salonen, Jarno; Hirvonen, Jouni; Caramella, Carla; Santos, Hélder A

    2014-11-01

    The wound healing stands as very complex and dynamic process, aiming the re-establishment of the damaged tissue's integrity and functionality. Thus, there is an emerging need for developing biopolymer-based composites capable of actively promoting cellular proliferation and reconstituting the extracellular matrix. The aims of the present work were to prepare and characterize biopolymer-functionalized porous silicon (PSi) microparticles, resulting in the development of drug delivery microsystems for future applications in wound healing. Thermally hydrocarbonized PSi (THCPSi) microparticles were coated with both chitosan and a mixture of chondroitin sulfate/hyaluronic acid, and subsequently loaded with two antibacterial model drugs, vancomycin and resveratrol. The biopolymer coating, drug loading degree and drug release behavior of the modified PSi microparticles were evaluated in vitro. The results showed that both the biopolymer coating and drug loading of the THCPSi microparticles were successfully achieved. In addition, a sustained release was observed for both the drugs tested. The viability and proliferation profiles of a fibroblast cell line exposed to the modified THCPSi microparticles and the subsequent reactive oxygen species (ROS) production were also evaluated. The cytotoxicity and proliferation results demonstrated less toxicity for the biopolymer-coated THCPSi microparticles at different concentrations and time points comparatively to the uncoated counterparts. The ROS production by the fibroblasts exposed to both uncoated and biopolymer-coated PSi microparticles showed that the modified PSi microparticles did not induce significant ROS production at the concentrations tested. Overall, the biopolymer-based PSi microparticles developed in this study are promising platforms for wound healing applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Salbutamol sulphate-ethylcellulose microparticles: formulation and in-vitro evaluation with emphasis on mathematical approaches

    Directory of Open Access Journals (Sweden)

    G Murtaza

    2009-10-01

    Full Text Available "n "nBackground and the purpose of the study: This study reports the laboratory optimization for the preparation of salbutamol sulphate-ethylcellulose microparticles by a non-solvent addition coacervation technique through adjustment of the ratio of salbutamol sulphate to ethylcellulose. The variation of drug release between the microparticles and tabletted microparticles was also investigated. "nMethods: In vitro release profiles of developed microparticles and tabletted microparticles were studied using USP XXIV dissolution apparatus I and II, respectively, in 450 ml double distilled water at 50 rpm maintained at 37°C. "nResults: White microparticles with no definite shape having good entrapment efficiency (96.68 to 97.83% and production yield (97.48 ± 1.21 to 98.35 ± 1.08% were obtained. In this investigation, initial burst effect was observed in the drug release behavior. The rate of drug release from microparticles decreased as the concentration of polyisobutylene was increased from 6% to 12% during microencapsulation. The release pattern of tabletted microparticles was affected significantly (p < 0.05 by the addition of hydroxy propyl methyl cellulose (HPMC as excepient and insignificantly (p > 0.05 by the type of dissolution media and stirring speed. Tabletted microparticles showed good stability and reproducibility. Ethylcellulose was found to be compatible with salbutamol sulphate. The drug release from all formulations was best fit to Higuchi's equation and the mechanism of drug release was anomalous diffusion from all formulations. "nConclusion: The results of this study suggest that by using ethylcellulose it is possible to design a single-unit, sustained-release oral dosage form of salbutamol sulphate for indication of twice a day.

  10. Microparticles engineered to highly express peroxisome proliferator-activated receptor-γ decreased inflammatory mediator production and increased adhesion of recipient monocytes.

    Directory of Open Access Journals (Sweden)

    Julie Sahler

    Full Text Available Circulating blood microparticles are submicron vesicles released primarily by megakaryocytes and platelets that act as transcellular communicators. Inflammatory conditions exhibit elevated blood microparticle numbers compared to healthy conditions. Direct functional consequences of microparticle composition, especially internal composition, on recipient cells are poorly understood. Our objective was to evaluate if microparticle composition could impact the function of recipient cells, particularly during inflammatory provocation. We therefore engineered the composition of megakaryocyte culture-derived microparticles to generate distinct microparticle populations that were given to human monocytes to assay for influences recipient cell function. Herein, we tested the responses of monocytes exposed to either control microparticles or microparticles that contain the anti-inflammatory transcription factor, peroxisome proliferator-activated receptor-γ (PPARγ. In order to normalize relative microparticle abundance from two microparticle populations, we implemented a novel approach that utilizes a Nanodrop Spectrophotometer to assay for microparticle density rather than concentration. We found that when given to peripheral blood mononuclear cells, microparticles were preferentially internalized by CD11b+ cells, and furthermore, microparticle composition had a profound functional impact on recipient monocytes. Specifically, microparticles containing PPARγ reduced activated monocyte production of the proinflammatory cytokines interleukin-8 and monocyte chemotactic protein-1 compared to activated monocytes exposed to control microparticles. Additionally, treatment with PPARγ microparticles greatly increased monocyte cell adherence. This change in morphology occurred simultaneously with increased production of the key extracellular matrix protein, fibronectin and increased expression of the fibronectin-binding integrin, ITGA5. PPARγ microparticles

  11. Microparticles engineered to highly express peroxisome proliferator-activated receptor-γ decreased inflammatory mediator production and increased adhesion of recipient monocytes.

    Science.gov (United States)

    Sahler, Julie; Woeller, Collynn F; Phipps, Richard P

    2014-01-01

    Circulating blood microparticles are submicron vesicles released primarily by megakaryocytes and platelets that act as transcellular communicators. Inflammatory conditions exhibit elevated blood microparticle numbers compared to healthy conditions. Direct functional consequences of microparticle composition, especially internal composition, on recipient cells are poorly understood. Our objective was to evaluate if microparticle composition could impact the function of recipient cells, particularly during inflammatory provocation. We therefore engineered the composition of megakaryocyte culture-derived microparticles to generate distinct microparticle populations that were given to human monocytes to assay for influences recipient cell function. Herein, we tested the responses of monocytes exposed to either control microparticles or microparticles that contain the anti-inflammatory transcription factor, peroxisome proliferator-activated receptor-γ (PPARγ). In order to normalize relative microparticle abundance from two microparticle populations, we implemented a novel approach that utilizes a Nanodrop Spectrophotometer to assay for microparticle density rather than concentration. We found that when given to peripheral blood mononuclear cells, microparticles were preferentially internalized by CD11b+ cells, and furthermore, microparticle composition had a profound functional impact on recipient monocytes. Specifically, microparticles containing PPARγ reduced activated monocyte production of the proinflammatory cytokines interleukin-8 and monocyte chemotactic protein-1 compared to activated monocytes exposed to control microparticles. Additionally, treatment with PPARγ microparticles greatly increased monocyte cell adherence. This change in morphology occurred simultaneously with increased production of the key extracellular matrix protein, fibronectin and increased expression of the fibronectin-binding integrin, ITGA5. PPARγ microparticles also changed monocyte

  12. Circulating Endothelial Microparticles: A Key Hallmark of Atherosclerosis Progression

    Directory of Open Access Journals (Sweden)

    Keshav Raj Paudel

    2016-01-01

    Full Text Available The levels of circulating microparticles (MPs are raised in various cardiovascular diseases. Their increased level in plasma is regarded as a biomarker of alteration in vascular function. The prominent MPs present in blood are endothelial microparticles (EMPs described as complex submicron (0.1 to 1.0 μm vesicles like structure, released in response to endothelium cell activation or apoptosis. EMPs possess both physiological and pathological effects and may promote oxidative stress and vascular inflammation. EMPs release is triggered by inducer like angiotensin II, lipopolysaccharide, and hydrogen peroxide leading to the progression of atherosclerosis. However, there are multiple physiological pathways for EMPs generation like NADPH oxidase derived endothelial ROS formation, Rho kinase pathway, and mitogen-activated protein kinases. Endothelial dysfunction is a key initiating event in atherosclerotic plaque formation. Atheroemboli, resulting from ruptured carotid plaques, is a major cause of stroke. Increasing evidence suggests that EMPs play an important role in the pathogenesis of cardiovascular disease, acting as a marker of damage, either exacerbating disease progression or triggering a repair response. In this regard, it has been suggested that EMPs have the potential to act as biomarkers of disease status. This review aims to provide updated information of EMPs in relation to atherosclerosis pathogenesis.

  13. New alginic acid–atenolol microparticles for inhalatory drug targeting

    Energy Technology Data Exchange (ETDEWEB)

    Ceschan, Nazareth Eliana; Bucalá, Verónica [Planta Piloto de Ingeniería Química (PLAPIQUI), CONICET, Universidad Nacional del Sur (UNS), Camino La Carrindanga Km 7, 8000 Bahía Blanca (Argentina); Departamento de Ingeniería Química, UNS, Avenida Alem 1253, 8000 Bahía Blanca (Argentina); Ramírez-Rigo, María Verónica, E-mail: vrrigo@plapiqui.edu.ar [Planta Piloto de Ingeniería Química (PLAPIQUI), CONICET, Universidad Nacional del Sur (UNS), Camino La Carrindanga Km 7, 8000 Bahía Blanca (Argentina); Departamento de Biología, Bioquímica y Farmacia, UNS, San Juan 670, 8000 Bahía Blanca (Argentina)

    2014-08-01

    The inhalatory route allows drug delivery for local or systemic treatments in a noninvasively way. The current tendency of inhalable systems is oriented to dry powder inhalers due to their advantages in terms of stability and efficiency. In this work, microparticles of atenolol (AT, basic antihypertensive drug) and alginic acid (AA, acid biocompatible polyelectrolyte) were obtained by spray drying. Several formulations, varying the relative composition AT/AA and the total solid content of the atomized dispersions, were tested. The powders were characterized by: Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry and Powder X-ray Diffraction, while also the following properties were measured: drug load efficiency, flow properties, particles size and density, moisture content, hygroscopicity and morphology. The ionic interaction between AA and AT was demonstrated, then the new chemical entity could improve the drug targeting to the respiratory membrane and increase its time residence due to the mucoadhesive properties of the AA polymeric chains. Powders exhibited high load efficiencies, low moisture contents, adequate mean aerodynamic diameters and high cumulative fraction of respirable particles (lower than 10 μm). - Highlights: • Novel particulate material to target atenolol to the respiratory membrane was developed. • Crumbled microparticles were obtained by spray drying of alginic–atenolol dispersions. • Ionic interaction between alginic acid and atenolol was demonstrated in the product. • Amorphous solids with low moisture content and high load efficiency were produced. • Relationships between the feed formulation and the product characteristics were found.

  14. Micro-Particles Motion in an Evaporating Droplet

    International Nuclear Information System (INIS)

    Jung, Jung Yeul; Yoo, Jung Yul; Kim, Young Won

    2007-01-01

    Nano-particles (on the order of 1 to 100 nm) contained within the droplet are moved by liquid flow and stacked at the contact line. The self-pinned contact line under the evaporating droplet is very interesting in the field of patterning and separation of particles and biocells. Models accounting for the nano-particles' flow and deposit patterns have been reported and verified by various experiments. Here, we report for the first time a phenomenon where micro-particles (on the order of 1 μm) in the colloid droplet flow to the center of droplet. There are three modes of fluid and particle flow in the evaporating droplet. In the first mode, a self-pinned contact line is maintained and the fluid and micro/nano-particles flow to the contact line. In the second mode, micro/nano-particles self-assemble at the near contact line, as reported by Jung and Kwak. In the final mode, only micro-particles are adverted to the center of the droplet due to movement of the contact line

  15. Optical binding of two microparticles levitated in vacuum

    Science.gov (United States)

    Arita, Yoshihiko; Wright, Ewan M.; Dholakia, Kishan

    2017-04-01

    Optical binding refers to an optically mediated inter-particle interaction that creates new equilibrium positions for closely spaced particles [1-5]. Optical binding of mesoscopic particles levitated in vacuum can pave the way towards the realisation of a large scale quantum bound array in cavity-optomechanics [6-9]. Recently we have demonstrated trapping and rotation of two mesoscopic particles in vacuum using a spatial-light-modulator-based approach to trap more than one particle, induce controlled rotation of individual particles, and mediate interparticle separation [10]. By trapping and rotating two vaterite particles, we observe intensity modulation of the scattered light at the sum and difference frequencies with respect to the individual rotation rates. This first demonstration of optical interference between two microparticles in vacuum has lead to a platform to explore optical binding. Here we demonstrate for the first time optically bound two microparticles mediated by light scattering in vacuum. We investigate autocorrelations between the two normal modes of oscillation, which are determined by the centre-of-mass and the relative positions of the two-particle system. In situ determination of the optical restoring force acting on the bound particles are based on measurement of the oscillation frequencies of the autocorrelation functions of the two normal modes, thereby providing a powerful and original platform to explore multiparticle entanglement in cavity-optomechanics.

  16. A stochastic DNA walker that traverses a microparticle surface

    Science.gov (United States)

    Jung, C.; Allen, P. B.; Ellington, A. D.

    2016-02-01

    Molecular machines have previously been designed that are propelled by DNAzymes, protein enzymes and strand displacement. These engineered machines typically move along precisely defined one- and two-dimensional tracks. Here, we report a DNA walker that uses hybridization to drive walking on DNA-coated microparticle surfaces. Through purely DNA:DNA hybridization reactions, the nanoscale movements of the walker can lead to the generation of a single-stranded product and the subsequent immobilization of fluorescent labels on the microparticle surface. This suggests that the system could be of use in analytical and diagnostic applications, similar to how strand exchange reactions in solution have been used for transducing and quantifying signals from isothermal molecular amplification assays. The walking behaviour is robust and the walker can take more than 30 continuous steps. The traversal of an unprogrammed, inhomogeneous surface is also due entirely to autonomous decisions made by the walker, behaviour analogous to amorphous chemical reaction network computations, which have been shown to lead to pattern formation.

  17. Acoustic bubble enhanced pinched flow fractionation for microparticle separation

    International Nuclear Information System (INIS)

    Zhou, Ran; Wang, Cheng

    2015-01-01

    Pinched flow fractionation is a simple method for separating micron-sized particles by size, but has certain intrinsic limitations, e.g. requirement of a pinched segment similar to particle size and limited separation distance. In this paper, we developed an acoustic bubble enhanced pinched flow fractionation (PFF) method for microparticle separation. The proposed technique utilized microbubble streaming flows to overcome the limitations of conventional PFF. Our device has demonstrated separation of different sized microparticles (diameters 10 and 2 μm) with a larger pinched segment (60 μm) and at different buffer/particle solution flow rate ratios (5–25). The separation distances between particles are larger (as much as twice as large) than those achieved with conventional PFF. In addition, the separation position and distance can be adjusted by changing the driving voltage. The robust performance is due to the unique features of the flow field inside the pinched segment. We investigated several factors, including flow rate ratio, total flow rate and driving voltage, that affect the separation performance. (paper)

  18. Delivery Systems for Biopharmaceuticals. Part I: Nanoparticles and Microparticles.

    Science.gov (United States)

    Silva, Ana C; Lopes, Carla M; Lobo, José M S; Amaral, Maria H

    2015-01-01

    Pharmaceutical biotechnology has been showing therapeutic success never achieved with conventional drug molecules. Therefore, biopharmaceutical products are currently well-established in clinic and the development of new ones is expected. These products comprise mainly therapeutic proteins, although nucleic acids and cells are also included. However, according to their sensitive molecular structures, the efficient delivery of biopharmaceuticals is challenging. Several delivery systems (e.g. microparticles and nanoparticles) composed of different materials (e.g. polymers and lipids) have been explored and demonstrated excellent outcomes, such as: high cellular transfection efficiency for nucleic acids, cell targeting, increased proteins and peptides bioavailability, improved immune response in vaccination, and viability maintenance of microencapsulated cells. Nonetheless, important issues need to be addressed before they reach clinics. For example, more in vivo studies in animals, accessing the toxicity potential and predicting in vivo failure of these delivery systems are required. This is the Part I of two review articles, which presents the state of the art of delivery systems for biopharmaceuticals. Part I deals with microparticles and polymeric and lipid nanoparticles.

  19. Circulating Red Cell–derived Microparticles in Human Malaria

    Science.gov (United States)

    Nantakomol, Duangdao; Dondorp, Arjen M.; Krudsood, Srivicha; Udomsangpetch, Rachanee; Pattanapanyasat, Kovit; Combes, Valery; Grau, Georges E.; White, Nicholas J.; Viriyavejakul, Parnpen; Day, Nicholas P.J.

    2011-01-01

    In patients with falciparum malaria, plasma concentrations of cell-derived microparticles correlate with disease severity. Using flow cytometry, we quantified red blood cell–derived microparticles (RMPs) in patients with malaria and identified the source and the factors associated with production. RMP concentrations were increased in patients with Plasmodium falciparum (n = 29; median, 457 RMPs/μL [range, 13–4,342 RMPs/μL]), Plasmodium vivax (n = 5; median, 409 RMPs/μL [range, 281–503/μL]), and Plasmodium malariae (n = 2; median, 163 RMPs/μL [range, 127–200 RMPs/μL]) compared with those in healthy subjects (n = 11; median, 8 RMPs/μL [range, 3–166 RMPs/μL]; P = .01). RMP concentrations were highest in patients with severe falciparum malaria (P = .01). Parasitized red cells produced >10 times more RMPs than did unparasitized cells, but the overall majority of RMPs still derived from uninfected red blood cells (URBCs). In cultures, RMP production increased as the parasites matured. Hemin and parasite products induced RMP production in URBCs, which was inhibited by N-acetylcysteine, suggesting heme-mediated oxidative stress as a pathway for the generation of RMPs. PMID:21282195

  20. Circulating red cell-derived microparticles in human malaria.

    Science.gov (United States)

    Nantakomol, Duangdao; Dondorp, Arjen M; Krudsood, Srivicha; Udomsangpetch, Rachanee; Pattanapanyasat, Kovit; Combes, Valery; Grau, Georges E; White, Nicholas J; Viriyavejakul, Parnpen; Day, Nicholas P J; Chotivanich, Kesinee

    2011-03-01

    In patients with falciparum malaria, plasma concentrations of cell-derived microparticles correlate with disease severity. Using flow cytometry, we quantified red blood cell-derived microparticles (RMPs) in patients with malaria and identified the source and the factors associated with production. RMP concentrations were increased in patients with Plasmodium falciparum (n = 29; median, 457 RMPs/μL [range, 13-4,342 RMPs/μL]), Plasmodium vivax (n = 5; median, 409 RMPs/μL [range, 281-503/μL]), and Plasmodium malariae (n = 2; median, 163 RMPs/μL [range, 127-200 RMPs/μL]) compared with those in healthy subjects (n = 11; median, 8 RMPs/μL [range, 3-166 RMPs/μL]; P = .01). RMP concentrations were highest in patients with severe falciparum malaria (P = .01). Parasitized red cells produced >10 times more RMPs than did unparasitized cells, but the overall majority of RMPs still derived from uninfected red blood cells (URBCs). In cultures, RMP production increased as the parasites matured. Hemin and parasite products induced RMP production in URBCs, which was inhibited by N-acetylcysteine, suggesting heme-mediated oxidative stress as a pathway for the generation of RMPs.

  1. Cytotoxicity assessment of porous silicon microparticles for ocular drug delivery.

    Science.gov (United States)

    Korhonen, Eveliina; Rönkkö, Seppo; Hillebrand, Satu; Riikonen, Joakim; Xu, Wujun; Järvinen, Kristiina; Lehto, Vesa-Pekka; Kauppinen, Anu

    2016-03-01

    Porous silicon (PSi) is a promising material for the delivery and sustained release of therapeutic molecules in various tissues. Due to the constant rinsing of cornea by tear solution as well as the short half-life of intravitreal drugs, the eye is an attractive target for controlled drug delivery systems, such as PSi microparticles. Inherent barriers ensure that PSi particles are retained in the eye, releasing drugs at the desired speed until they slowly break down into harmless silicic acid. Here, we have examined the in vitro cytotoxicity of positively and negatively charged thermally oxidized (TOPSi) and thermally carbonized (TCPSi) porous silicon microparticles on human corneal epithelial (HCE) and retinal pigment epithelial (ARPE-19) cells. In addition to ocular assessment under an inverted microscope, cellular viability was evaluated using the CellTiter Blue™, CellTiter Fluor™, and lactate dehydrogenase (LDH) assays. CellTiter Fluor proved to be a suitable assay but due to non-specific and interfering responses, neither CellTiter Blue nor LDH assays should be used when evaluating PSi particles. Our results suggest that the toxicity of PSi particles is concentration-dependent, but at least at concentrations less than 200μg/ml, both positively and negatively charged PSi particles are well tolerated by human corneal and retinal epithelial cells and therefore applicable for delivering drug molecules into ocular tissues. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Asymmetric Carrier Random PWM

    DEFF Research Database (Denmark)

    Mathe, Laszlo; Lungeanu, Florin; Rasmussen, Peter Omand

    2010-01-01

    index. The flat motor current spectrum generates an acoustical noise close to the white noise, which may improve the acoustical performance of the drive. The new carrier wave is easy to implement digitally, without employing any external circuits. The modulation method can be used in open, as well...

  3. Willis H Carrier

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 17; Issue 2. Willis H. Carrier - Father of Air Conditioning. R V Simha. General Article Volume 17 Issue 2 February 2012 pp 117-138. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/017/02/0117-0138 ...

  4. Early results of microwave transmission experiments through an overly dense rectangular plasma sheet with microparticle injection

    Energy Technology Data Exchange (ETDEWEB)

    Gillman, Eric D., E-mail: eric.gillman.ctr@nrl.navy.mil [National Research Council Postdoctoral Associate at the U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Amatucci, W. E. [U.S. Naval Research Laboratory, Washington, DC 20375 (United States)

    2014-06-15

    These experiments utilize a linear hollow cathode to create a dense, rectangular plasma sheet to simulate the plasma layer surrounding vehicles traveling at hypersonic velocities within the Earth's atmosphere. Injection of fine dielectric microparticles significantly reduces the electron density and therefore lowers the electron plasma frequency by binding a significant portion of the bulk free electrons to the relatively massive microparticles. Measurements show that microwave transmission through this previously overly dense, impenetrable plasma layer increases with the injection of alumina microparticles approximately 60 μm in diameter. This method of electron depletion is a potential means of mitigating the radio communications blackout experienced by hypersonic vehicles.

  5. Concept of safe tank-type water cooled and moderated reactor with HTGR microparticle fuel compacts

    International Nuclear Information System (INIS)

    Gol'tsev, A.O.; Kukharkin, N.E.; Mosevitskij, I.S.; Ponomarev-Stepnoj, N.N.; Popov, S.V.; Udyanskij, Yu.N.; Tsibul'skij, V.F.

    1993-01-01

    Concept of safe tank-type water-cooled and moderated reactor on the basis of HTGR fuel microparticles which enable to avoid environment contamination with radioactive products under severe accidents, is proposed. Results of neutron-physical and thermal-physical studies of water cooled and moderated reactor with HTGR microparticle compacts are presented. Characteristics of two reactors with thermal power of 500 and 1500 MW are indicated within the concept frames. The reactor behaviour under severe accident connected with complete loss of water coolant is considered. It is shown that under such an accident the fission products release from fuel microparticles does not occur

  6. Sealed substrate carrier for electroplating

    Science.gov (United States)

    Ganti, Kalyana Bhargava [Fremont, CA

    2012-07-17

    One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The substrate carrier includes a non-conductive carrier body on which the substrates are held, and conductive lines are embedded within the carrier body. A conductive bus bar is embedded into a top side of the carrier body and is conductively coupled to the conductive lines. A thermoplastic overmold covers a portion of the bus bar, and there is a plastic-to-plastic bond between the thermoplastic overmold and the non-conductive carrier body. Other embodiments, aspects and features are also disclosed.

  7. Comparison of spray congealing and melt emulsification methods for the incorporation of the water-soluble salbutamol sulphate in lipid microparticles.

    Science.gov (United States)

    Scalia, Santo; Traini, Daniela; Young, Paul M; Di Sabatino, Marcello; Passerini, Nadia; Albertini, Beatrice

    2013-02-01

    Salbutamol sulphate is widely used as bronchodilator for the treatment of asthma. Its use is limited by the relatively short duration of action and hence sustained delivery of salbutamol sulphate offers potential benefits to patients. This study explores the preparation of lipid microparticles (LMs) as biocompatible carrier for the prolonged release of salbutamol sulphate. The LMs were produced using different lipidic materials and surfactants, by classical melt emulsification-based methods (oil-in-water and water-in-oil-in-water emulsions) and the spray congealing technique. For the LMs obtained by melt emulsification a lack of release modulation was observed. On the other hand, the sustained release of salbutamol sulphate was achieved with glyceryl behenate microparticles prepared by spray congealing. These LMs were characterized by scanning electron microscopy, X-ray diffractometry and differential scanning calorimetry. The drug loading was 4.72% (w/w). The particle size distribution measured by laser diffraction and electrical zone sensing was represented by a volume median diameter (Dv(50)) of 51.7-71.4 µm. Increasing the atomization air pressure from 4 to 8 bar produced a decrease of the Dv(50) to 12.7-17.5 µm. Incorporation of the hydrophilic salbutamol sulphate into LMs with sustained release characteristics was achieved by spray congealing.

  8. Development of a magnetic system for the treatment of Helicobacter pylori infections

    International Nuclear Information System (INIS)

    Silva, Erica L.; Carvalho, Juliana F.; Pontes, Thales R.F.; Oliveira, Elquio E.; Francelino, Barbara L.; Medeiros, Aldo C.; Egito, E. Socrates T. do; Araujo, Jose H.; Carrico, Artur S.

    2009-01-01

    We report a study to develop a magnetic system for local delivery of amoxicillin. Magnetite microparticles produced by coprecipitation were coated with a solution of amoxicillin and Eudragit S100 by spray drying. Scanning electron microscopy, optical microscopy, X-ray powder diffraction and vibrating sample magnetometry revealed that the particles were superparamagnetic, with an average diameter of 17.2 μm, and an initial susceptibility controllable by the magnetite content in the suspension feeding the sprayer. Our results suggest a possible way to treat Helicobacter pylori infections, using an oral drug delivery system, and open prospects to coat magnetic microparticles by spray drying for biomedical applications.

  9. Development of a magnetic system for the treatment of Helicobacter pylori infections

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Erica L.; Carvalho, Juliana F.; Pontes, Thales R.F.; Oliveira, Elquio E. [Departamento de Farmacia, Universidade Federal do Rio Grande do Norte, Rua Gal Gustavo Cordeiro de Farias s.n, Petropolis, 59010-180 Natal-RN (Brazil); Francelino, Barbara L.; Medeiros, Aldo C. [Departamento de Medicina, Universidade Federal do Rio Grande do Norte, Rua Gal Gustavo Cordeiro de Farias s.n, Petropolis, 59010-180 Natal-RN (Brazil); Egito, E. Socrates T. do [Departamento de Farmacia, Universidade Federal do Rio Grande do Norte, Rua Gal Gustavo Cordeiro de Farias s.n, Petropolis, 59010-180 Natal-RN (Brazil); Araujo, Jose H. [Departamento de Fisica Teorica e Experimental, Universidade Federal do Rio Grande do Norte, Campus Universitario, 59078-970 Natal-RN (Brazil); Carrico, Artur S. [Departamento de Fisica Teorica e Experimental, Universidade Federal do Rio Grande do Norte, Campus Universitario, 59078-970 Natal-RN (Brazil)], E-mail: ascarrico@dfte.ufrn.br

    2009-05-15

    We report a study to develop a magnetic system for local delivery of amoxicillin. Magnetite microparticles produced by coprecipitation were coated with a solution of amoxicillin and Eudragit S100 by spray drying. Scanning electron microscopy, optical microscopy, X-ray powder diffraction and vibrating sample magnetometry revealed that the particles were superparamagnetic, with an average diameter of 17.2 {mu}m, and an initial susceptibility controllable by the magnetite content in the suspension feeding the sprayer. Our results suggest a possible way to treat Helicobacter pylori infections, using an oral drug delivery system, and open prospects to coat magnetic microparticles by spray drying for biomedical applications.

  10. Maltodextrin: A consummate carrier for spray-drying of xylooligosaccharides.

    Science.gov (United States)

    Zhang, Liangqing; Zeng, Xianhai; Fu, Nan; Tang, Xing; Sun, Yong; Lin, Lu

    2018-04-01

    The aim of this study was to evaluate the influence of spray-drying on the powder qualities and microstructures of prebiotic xylooligosaccharides (XOS). The relationships between glass transition temperature (T g ) and XOS retention, moisture content, drying yield as well as specific surface area under different inlet air temperatures and maltodextrin concentrations were investigated. Antioxidant activity retention, hygroscopicity, color attributes, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) of the spray-dried XOS product were also assessed. The results indicated that an increase in inlet air temperature decreased the moisture content, hence the T g value was increased. Higher maltodextrin concentration increased the T g value, and was attributed to the molecular weight increase. The wall deposition was a tendency to occur when the temperature beyond the T g , reduced the drying yield. Higher temperature and wall deposition promoted the decomposition of XOS into monosaccharide. The crust formation rate of droplets and stickiness of microparticles were affected by T g , and hence, influenced the specific surface area. The antioxidant activity retention of XOS exhibited a concentration-dependent behavior. The hygroscopicity of the microparticles could be reduced by both of the low inlet air temperature and high maltodextrin concentration. According to the results of color attributes, XRD and SEM, the particles were colorless and amorphous, and tended to become more spherical and scattered with the addition of maltodextrin. The FT-IR analysis confirmed that no chemical reaction occurred between XOS and agent, which indicated that maltodextrin is a promising carrier for producing bioactive XOS powder. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Magnetic filtered plasma deposition and implantation technique

    CERN Document Server

    Zhang Hui Xing; Wu Xian Ying

    2002-01-01

    A high dense metal plasma can be produced by using cathodic vacuum arc discharge technique. The microparticles emitted from the cathode in the metal plasma can be removed when the metal plasma passes through the magnetic filter. It is a new technique for making high quality, fine and close thin films which have very widespread applications. The authors describe the applications of cathodic vacuum arc technique, and then a filtered plasma deposition and ion implantation system as well as its applications

  12. Postprandial changes in the phospholipid composition of circulating microparticles are not associated with coagulation activation

    NARCIS (Netherlands)

    Tushuizen, Maarten E.; Diamant, Michaela; Peypers, Erik G.; Hoek, Frans J.; Heine, Robert J.; Sturk, Augueste; Nieuwland, Rienk

    2012-01-01

    Introduction: Evidence is present that the phospholipid composition of circulating cell-derived microparticles (MP) affects coagulation in vivo, and that postprandial metabolic alterations may be associated with hypercoagulable state. Our objective was to investigate whether postprandial metabolic

  13. Biodegradable Microparticles for Simultaneous Detection of Counterfeit and Deteriorated Edible Products

    NARCIS (Netherlands)

    Rehor, Ivan; van Vreeswijk, Sophie; Vermonden, Tina; Hennink, Wim E.; Kegel, Willem K.; Eral, Huseyin Burak

    2017-01-01

    In an era of globalized trade relations where food and pharmaceutical products cross borders effortlessly, consumers face counterfeit and deteriorated products at elevated rates. This paper presents multifunctional, biodegradable hydrogel microparticles that can provide information on the

  14. Distinct features of circulating microparticles and their relationship to clinical manifestations in systemic lupus erythematosus

    DEFF Research Database (Denmark)

    Nielsen, Christoffer T; Østergaard, Ole; Johnsen, Christina

    2011-01-01

    Characterization of the abundance, origin, and annexin V (AnxV)-binding capabilities of circulating microparticles (MPs) in SLE patients and healthy controls and to determine any associations with clinical parameters....

  15. Apheresis platelet concentrates contain platelet-derived and endothelial cell-derived microparticles

    NARCIS (Netherlands)

    Rank, A.; Nieuwland, R.; Liebhardt, S.; Iberer, M.; Grützner, S.; Toth, B.; Pihusch, R.

    2011-01-01

    Background and Objectives Microparticles (MP) are membrane vesicles with thrombogenic and immunomodulatory properties. We determined MP subgroups from resting platelets, activated platelets and endothelial cells in donors and apheresis platelet concentrates (PC). Material and Methods MP were double

  16. Preparation of Antheraea pernyi Silk Fibroin Microparticles through a Facile Electrospinning Method

    Directory of Open Access Journals (Sweden)

    Xiufang Li

    2016-01-01

    Full Text Available The goal of this study was to fabricate Antheraea pernyi silk fibroin (ASF microparticles using electrospinning under mild processing conditions. To improve processability of the ASF solution, poly(ethylene oxide (PEO was used to regulate viscosity of ASF solution for electrospinning. It was found that the blend of ASF with PEO could form a bead-on-string structure with well spherical particles. Furthermore, aqueous ethanol and ultrasonic treatments could disrupt the nanofibrillar string structure between particles and ultimately produced water-insoluble ASF particles with submicron scale. Cell viability studies indicated that the ASF microparticles were nontoxic to EA926 cells. Moreover, fluorescent images based on FITC labeling showed that the ASF microparticles were easily uptaken by the cells. Aqueous-based electrospinning provides a potentially useful option for the fabrication of ASF microparticles based on this unique fibrous protein.

  17. Reciprocity Method for Obtaining the Far Fields Generated by a Source Inside or Near a Microparticle

    National Research Council Canada - National Science Library

    Hill, Steven

    1997-01-01

    We show that the far fields generated by a source inside or near a microparticle can be obtained readily by using the reciprocity theorem along with the internal or near fields generated by plane wave illumination...

  18. Restructuring of microparticles in nuclear ceramic materials. Part III. Form distribution

    International Nuclear Information System (INIS)

    Lameiras, F.S.

    1991-01-01

    According to the present model, the modification of the microparticle form, tending to an equiaxial one, is a way to decrease the interface energy of a microparticle set. If the microparticles are dispersed, these ones tend to the spherical form. If they form aggregates (grains), the interface energy is stored in the grain boundaries, triple lines and quadruple points. A mean topological structure combining two kinds of nearly equiaxed polyhedra is proposed for aggregates of microparticles in order to minimize the surface of the grain boundaries, the length of the triple lines and the number of the quadruple points. As the restructuring evolutes, the average grain form tends to take the one of this polyhedra structure. (author)

  19. Multipole electrodynamic ion trap geometries for microparticle confinement under standard ambient temperature and pressure conditions

    Energy Technology Data Exchange (ETDEWEB)

    Mihalcea, Bogdan M., E-mail: bogdan.mihalcea@inflpr.ro; Vişan, Gina T.; Ganciu, Mihai [National Institute for Laser, Plasma and Radiation Physics (INFLPR), Atomiştilor Str. Nr. 409, 077125 Măgurele, Ilfov (Romania); Giurgiu, Liviu C. [University of Bucharest, Faculty of Physics, Atomistilor Str. Nr. 405, 077125 Măgurele (Romania); Stan, Cristina [Department of Physics, Politehnica University, 313 Splaiul Independenţei, RO-060042 Bucharest (Romania); Filinov, Vladimir; Lapitsky, Dmitry, E-mail: dmitrucho@yandex.ru; Deputatova, Lidiya; Syrovatka, Roman [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya Str. 13, Bd. 2, 125412 Moscow (Russian Federation)

    2016-03-21

    Trapping of microparticles and aerosols is of great interest for physics and chemistry. We report microparticle trapping in case of multipole linear Paul trap geometries, operating under standard ambient temperature and pressure conditions. An 8- and 12-electrode linear trap geometries have been designed and tested with an aim to achieve trapping for larger number of particles and to study microparticle dynamical stability in electrodynamic fields. We report emergence of planar and volume ordered structures of microparticles, depending on the a.c. trapping frequency and particle specific charge ratio. The electric potential within the trap is mapped using the electrolytic tank method. Particle dynamics is simulated using a stochastic Langevin equation. We emphasize extended regions of stable trapping with respect to quadrupole traps, as well as good agreement between experiment and numerical simulations.

  20. Multipole electrodynamic ion trap geometries for microparticle confinement under standard ambient temperature and pressure conditions

    International Nuclear Information System (INIS)

    Mihalcea, Bogdan M.; Vişan, Gina T.; Ganciu, Mihai; Giurgiu, Liviu C.; Stan, Cristina; Filinov, Vladimir; Lapitsky, Dmitry; Deputatova, Lidiya; Syrovatka, Roman

    2016-01-01

    Trapping of microparticles and aerosols is of great interest for physics and chemistry. We report microparticle trapping in case of multipole linear Paul trap geometries, operating under standard ambient temperature and pressure conditions. An 8- and 12-electrode linear trap geometries have been designed and tested with an aim to achieve trapping for larger number of particles and to study microparticle dynamical stability in electrodynamic fields. We report emergence of planar and volume ordered structures of microparticles, depending on the a.c. trapping frequency and particle specific charge ratio. The electric potential within the trap is mapped using the electrolytic tank method. Particle dynamics is simulated using a stochastic Langevin equation. We emphasize extended regions of stable trapping with respect to quadrupole traps, as well as good agreement between experiment and numerical simulations.

  1. Counter-Propagating Optical Trapping System for Size and Refractive Index Measurement of Microparticles

    National Research Council Canada - National Science Library

    Flynn, Richard A; Shao, Bing; Chachisvilis, Mirianas; Ozkan, Mihrimah; Esener, Sadik C

    2005-01-01

    We propose and demonstrate a novel approach to measure the size and refractive index of microparticles based on two beam optical trapping, where forward scattered light is detected to give information about the particle...

  2. Optical and non-optical methods for detection and characterization of microparticles and exosomes

    NARCIS (Netherlands)

    van der Pol, E.; Hoekstra, A.G.; Sturk, A.; Otto, C.; van Leeuwen, T.G.; Nieuwland, R.

    2010-01-01

    Microparticles and exosomes are cell-derived microvesicles present in body fluids that play a role in coagulation, inflammation, cellular homeostasis and survival, intercellular communication, and transport. Despite increasing scientific and clinical interest, no standard procedures are available

  3. Functionalised alginate flow seeding microparticles for use in Particle Image Velocimetry (PIV).

    Science.gov (United States)

    Varela, Sylvana; Balagué, Isaac; Sancho, Irene; Ertürk, Nihal; Ferrando, Montserrat; Vernet, Anton

    2016-01-01

    Alginate microparticles as flow seeding fulfil all the requirements that are recommended for the velocity measurements in Particle Image Velocimetry (PIV). These spherical microparticles offer the advantage of being environmentally friendly, having excellent seeding properties and they can be produced via a very simple process. In the present study, the performances of alginate microparticles functionalised with a fluorescent dye, Rhodamine B (RhB), for PIV have been studied. The efficacy of fluorescence is appreciated in a number of PIV applications since it can boost the signal-to-noise ratio. Alginate microparticles functionalised with RhB have high emission efficiency, desirable match with fluid density and controlled size. The study of the particles behaviour in strong acid and basic solutions and ammonia is also included. This type of particles can be used for measurements with PIV and Planar Laser Induced Fluorescence (PLIF) simultaneously, including acid-base reactions.

  4. Motor carrier evaluation program

    International Nuclear Information System (INIS)

    Portsmouth, James

    1992-01-01

    The U.S. Department of Energy-Headquarters (DOE-HQ), Transportation Management Program (TMP) has the overall responsibility to provide a well-managed transportation program for the safe, efficient, and economical transportation of DOE-owned materials. The DOE-TMP has established an excellent safety record in the transportation of hazardous materials including radioactive materials and radioactive wastes. This safety record can be maintained only through continued diligence and sustained effort on the part of the DOE-TMP, its field offices, and the contractors' organizations. Key elements in the DOE'S effective hazardous and radioactive materials shipping program are (1) integrity of packages, (2) strict adherence to regulations and procedures, (3) trained personnel, (4) complete management support, and (5) use of the best commercial carriers. The DOE Motor Carrier Evaluation Program was developed to better define the criteria and methodology needed to identify motor carriers for use in the transportation of Highway Route Controlled Quantities (HRCQ), Truck Load (TL) quantities of radioactive materials, hazardous materials and waste. (author)

  5. Carrier transport uphill. I. General

    DEFF Research Database (Denmark)

    Rosenberg, T; Wilbrandt, W

    1963-01-01

    A quantitative treatment of a carrier pump operating with two carrier forms C and Z is presented. Asymmetric metabolic reactions are assumed to transform Z into C on one and C into Z on the other side of the membrane, establishing a carrier cycle. The kinetical consequences of this mechanism...

  6. Analysis of sorption into single ODS-silica gel microparticles in acetonitrile-water.

    Science.gov (United States)

    Nakatani, Kiyoharu; Kakizaki, Hiroshi

    2003-08-01

    Intraparticle mass transfer processes of Phenol Blue (PB) in single octadecylsilyl (ODS)-silica gel microparticles in acetonitrile-water were analyzed by microcapillary manipulation and microabsorption methods. An absorption maximum of PB, the sorption isotherm parameters, and the sorption rate in the microparticle system were highly dependent on the percentage of acetonitrile in solution. The results are discussed in terms of the microscopic polarity surrounding PB in the ODS phase and the relationship between the isotherm parameters and the sorption rate.

  7. Increased CD39 Nucleotidase Activity on Microparticles from Patients with Idiopathic Pulmonary Arterial Hypertension

    Science.gov (United States)

    Visovatti, Scott H.; Hyman, Matthew C.; Bouis, Diane; Neubig, Richard; McLaughlin, Vallerie V.; Pinsky, David J.

    2012-01-01

    Background Idiopathic pulmonary arterial hypertension (IPAH) is a devastating disease characterized by increased pulmonary vascular resistance, smooth muscle and endothelial cell proliferation, perivascular inflammatory infiltrates, and in situ thrombosis. Circulating intravascular ATP, ADP, AMP and adenosine activate purinergic cell signaling pathways and appear to induce many of the same pathologic processes that underlie IPAH. Extracellular dephosphorylation of ATP to ADP and AMP occurs primarily via CD39 (ENTPD1), an ectonucleotidase found on the surface of leukocytes, platelets, and endothelial cells [1]. Microparticles are micron-sized phospholipid vesicles formed from the membranes of platelets and endothelial cells. Objectives: Studies here examine whether CD39 is an important microparticle surface nucleotidase, and whether patients with IPAH have altered microparticle-bound CD39 activity that may contribute to the pathophysiology of the disease. Methodology/ Principal Findings Kinetic parameters, inhibitor blocking experiments, and immunogold labeling with electron microscopy support the role of CD39 as a major nucleotidase on the surface of microparticles. Comparison of microparticle surface CD39 expression and nucleotidase activity in 10 patients with advanced IPAH and 10 healthy controls using flow cytometry and thin layer chromatograph demonstrate the following: 1) circulating platelet (CD39+CD31+CD42b+) and endothelial (CD39+CD31+CD42b−) microparticle subpopulations in patients with IPAH show increased CD39 expression; 2) microparticle ATPase and ADPase activity in patients with IPAH is increased. Conclusions/ Significance We demonstrate for the first time increased CD39 expression and function on circulating microparticles in patients with IPAH. Further research is needed to elucidate whether these findings identify an important trigger for the development of the disease, or reflect a physiologic response to IPAH. PMID:22792409

  8. The van der Waals interaction of microparticles with a substrate characterized by a nonlocal response

    International Nuclear Information System (INIS)

    Dorofeyev, Illarion

    2007-01-01

    The van der Waals energy of the system constituted by a microparticle and a solid surface characterized by a nonlocal response is calculated taking into account an influence of another microparticle. A saturation of the dispersion interaction at short distances from the surface both for the spectral density of energy and for the total energy is shown. The known McLachlan expression for the pair and triple energies in the case of local media directly follows from the obtained general expression

  9. Investigation of Water Absorption and Diffusion in Microparticles Containing Xylitol to Provide a Cooling Effect by Thermal Analysis

    Science.gov (United States)

    Salaün, F.; Bedek, G.; Devaux, E.; Dupont, D.; Deranton, D.

    2009-08-01

    Polyurethane microparticles containing xylitol as a sweat sensor system were prepared by interfacial polymerization. The structural and thermal properties of the resultant microparticles were studied. The surface morphology and chemical structure of microparticles were investigated using an optical microscope (OM) and a Fourier-transform infrared spectroscope (FTIR), respectively. The thermal properties of samples were investigated by thermogravimetric analysis (TGA) and by differential scanning calorimetry (DSC). Thus, two types of microparticles were synthesized by varying the percentage of monomers introduced. The obtained morphology is directly related to the synthesis conditions. DSC analysis indicated that the mass content of crystalline xylitol was up to 63.8 %, which resulted in a high enthalpy of dilution of 127.7 J · g-1. Furthermore, the water release rate monitored by TGA analysis was found to be faster from the microparticles than from raw xylitol. Thus, the microparticles could be applied for thermal energy storage and moisture sensor enhancement.

  10. A study on arrangement characteristics of microparticles in sedimentation on flat and round substrates

    Science.gov (United States)

    Yeo, Eunju; Son, Minhee; Kim, Kwanoh; Kim, Jeong Hwan; Yoo, Yeong-Eun; Choi, Doo-Sun; Kim, Jungchul; Yoon, Seok Ho; Yoon, Jae Sung

    2017-12-01

    Recent advances of microfabrication techniques have enabled diverse structures and devices on the microscale. This fabrication method using microparticles is one of the most promising technologies because it can provide a cost effective process for large areas. So, many researchers are studying modulation and manipulation of the microparticles in solution to obtain a proper arrangement. However, the microparticles are in sedimentation status during the process in many cases, which makes it difficult to control their arrangement. In this study, droplets containing microparticles were placed on a substrate with minimal force and we investigated the arrangement of these microparticles after evaporation of the liquid. Experiments have been performed with upward and downward substrates to change the direction of gravity. The geometry of substrates was also changed, which were flat or round. The results show that the arrangement depends on the size of particles and gravity and geometry of the substrate. The arrangement also depends on the movement of the contact line of the droplets, which may recede or be pinned during evaporation. This study is expected to provide a method of the fabrication process for microparticles which may not be easily manipulated due to sedimentation.

  11. Circulating endothelial cells and procoagulant microparticles in patients with glioblastoma: prognostic value.

    Directory of Open Access Journals (Sweden)

    Gaspar Reynés

    Full Text Available AIM: Circulating endothelial cells and microparticles are prognostic factors in cancer. However, their prognostic and predictive value in patients with glioblastoma is unclear. The objective of this study was to investigate the potential prognostic value of circulating endothelial cells and microparticles in patients with newly diagnosed glioblastoma treated with standard radiotherapy and concomitant temozolomide. In addition, we have analyzed the methylation status of the MGMT promoter. METHODS: Peripheral blood samples were obtained before and at the end of the concomitant treatment. Blood samples from healthy volunteers were also obtained as controls. Endothelial cells were measured by an immunomagnetic technique and immunofluorescence microscopy. Microparticles were quantified by flow cytometry. Microparticle-mediated procoagulant activity was measured by endogen thrombin generation and by phospholipid-dependent clotting time. Methylation status of MGMT promoter was determined by multiplex ligation-dependent probe amplification. RESULTS: Pretreatment levels of circulating endothelial cells and microparticles were higher in patients than in controls (p<0.001. After treatment, levels of microparticles and thrombin generation decreased, and phospholipid-dependent clotting time increased significantly. A high pretreatment endothelial cell count, corresponding to the 99(th percentile in controls, was associated with poor overall survival. MGMT promoter methylation was present in 27% of tumor samples and was associated to a higher overall survival (66 weeks vs 30 weeks, p<0.004. CONCLUSION: Levels of circulating endothelial cells may have prognostic value in patients with glioblastoma.

  12. Preparation, Characterization and Properties of Alginate/Poly(γ-glutamic acid) Composite Microparticles.

    Science.gov (United States)

    Tong, Zongrui; Chen, Yu; Liu, Yang; Tong, Li; Chu, Jiamian; Xiao, Kecen; Zhou, Zhiyu; Dong, Wenbo; Chu, Xingwu

    2017-04-11

    Alginate (Alg) is a renewable polymer with excellent hemostatic properties and biocapability and is widely used for hemostatic wound dressing. However, the swelling properties of alginate-based wound dressings need to be promoted to meet the requirements of wider application. Poly( γ -glutamic acid) (PGA) is a natural polymer with high hydrophility. In the current study, novel Alg/PGA composite microparticles with double network structure were prepared by the emulsification/internal gelation method. It was found from the structure characterization that a double network structure was formed in the composite microparticles due to the ion chelation interaction between Ca 2+ and the carboxylate groups of Alg and PGA and the electrostatic interaction between the secondary amine group of PGA and the carboxylate groups of Alg and PGA. The swelling behavior of the composite microparticles was significantly improved due to the high hydrophility of PGA. Influences of the preparing conditions on the swelling behavior of the composites were investigated. The porous microparticles could be formed while compositing of PGA. Thermal stability was studied by thermogravimetric analysis method. Moreover, in vitro cytocompatibility test of microparticles exhibited good biocompatibility with L929 cells. All results indicated that such Alg/PGA composite microparticles are a promising candidate in the field of wound dressing for hemostasis or rapid removal of exudates.

  13. Properties of gelatin-based films incorporated with chitosan-coated microparticles charged with rutin.

    Science.gov (United States)

    Dammak, Ilyes; Bittante, Ana Mônica Quinta Barbosa; Lourenço, Rodrigo Vinicius; do Amaral Sobral, Paulo José

    2017-08-01

    The aim of this study was development an active film based on gelatin incorporated with antioxidant, rutin carried into microparticles. The complexation between oppositely charged lecithin and chitosan was applied to prepare the chitosan-coated microparticles. The generated microparticles had an average size of 520±4nm and a span of 0.3 were formulated by a rotor-stator homogenize at the homogenization speed 10,000rpm. Composite films were prepared by incorporating chitosan-coated microparticles, at various concentrations (0.05, 0.1, 0.5, or 1% (based on the weight of the gelatin powder)) in the gelatin-based films. For the prepared films, the results showed that obtained physicochemical, water vapor barrier, and mechanical were compared with native gelatin film with a slight decrease for chitosan concentration higher than 0.5%. The microstructure studies done by scanning electron microscopes, revealed different micropores embedded with oil resulting from the incorporation of the microparticles into the gelatin matrix. Moreover, the calorimetric results were comparable to those of gelatin control film with T g value 45°C and increased crystallinity percentage with increasing incorporation of microparticles. This original concept of composite biodegradable films may thus be a good alternative to incorporate liposoluble active compounds to design an active packaging with good properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Thiol functionalized polymethacrylic acid-based hydrogel microparticles for oral insulin delivery.

    Science.gov (United States)

    Sajeesh, S; Vauthier, C; Gueutin, C; Ponchel, G; Sharma, Chandra P

    2010-08-01

    In the present study thiol functionalized polymethacrylic acid-polyethylene glycol-chitosan (PCP)-based hydrogel microparticles were utilized to develop an oral insulin delivery system. Thiol modification was achieved by grafting cysteine to the activated surface carboxyl groups of PCP hydrogels (Cys-PCP). Swelling and insulin loading/release experiments were conducted on these particles. The ability of these particles to inhibit protease enzymes was evaluated under in vitro experimental conditions. Insulin transport experiments were performed on Caco-2 cell monolayers and excised intestinal tissue with an Ussing chamber set-up. Finally, the efficacy of insulin-loaded particles in reducing the blood glucose level in streptozotocin-induced diabetic rats was investigated. Thiolated hydrogel microparticles showed less swelling and had a lower insulin encapsulation efficiency as compared with unmodified PCP particles. PCP and Cys-PCP microparticles were able to inhibit protease enzymes under in vitro conditions. Thiolation was an effective strategy to improve insulin absorption across Caco-2 cell monolayers, however, the effect was reduced in the experiments using excised rat intestinal tissue. Nevertheless, functionalized microparticles were more effective in eliciting a pharmacological response in diabetic animal, as compared with unmodified PCP microparticles. From these studies thiolation of hydrogel microparticles seems to be a promising approach to improve oral delivery of proteins/peptides. Copyright 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  15. Development of biodegradable methylprednisolone microparticles for treatment of articular pathology using a spray-drying technique

    Science.gov (United States)

    Tobar-Grande, Blanca; Godoy, Ricardo; Bustos, Paulina; von Plessing, Carlos; Fattal, Elias; Tsapis, Nicolas; Olave, Claudia; Gómez-Gaete, Carolina

    2013-01-01

    In this work, microparticles were prepared by spray-drying using albumin, chondroitin sulfate, and hyaluronic acid as excipients to create a controlled-release methylprednisolone system for use in inflammatory disorders such as arthritis. Scanning electron microscopy demonstrated that these microparticles were almost spherical, with development of surface wrinkling as the methylprednisolone load in the formulation was increased. The methylprednisolone load also had a direct influence on the mean diameter and zeta potential of the microparticles. Interactions between formulation excipients and the active drug were evaluated by x-ray diffraction, differential scanning calorimetry, and thermal gravimetric analysis, showing limited amounts of methylprednisolone in a crystalline state in the loaded microparticles. The encapsulation efficiency of methylprednisolone was approximately 89% in all formulations. The rate of methylprednisolone release from the microparticles depended on the initial drug load in the formulation. In vitro cytotoxic evaluation using THP-1 cells showed that none of the formulations prepared triggered an inflammatory response on release of interleukin-1β, nor did they affect cellular viability, except for the 9.1% methylprednisolone formulation, which was the maximum test concentration used. The microparticles developed in this study have characteristics amenable to a therapeutic role in inflammatory pathology, such as arthritis. PMID:23737670

  16. Luminescence investigation of Yb3+/Er3+ codoped single LiYF4 microparticle

    International Nuclear Information System (INIS)

    Gao, Wei; Zheng, Hairong; He, Enjie; Lu, Ying; Gao, Fangqi

    2014-01-01

    Tetragonal phase LiYF 4 :Yb 3+ /Er 3+ microparticles are synthesized via facile hydrothermal method. Single LiYF 4 microparticle is excited with IR laser at 980 nm in a confocal setup, and strong green and weak red emissions are observed. It is found that single LiYF 4 :Yb 3+ /Er 3+ microparticle with sub-structure presents stronger upconversion luminescence emission and smaller intensity ratio of red to green emission than that from LiYF 4 :Yb 3+ /Er 3+ microparticle with no sub-structure. The possible mechanism, the influence of particle size and the existence of EDTA on the upconversion luminescence emission are investigated. The current study suggests that the luminescence observation with single micropaticle can effectively avoid the influence of environment and neighbor particles, which is important for investigating the luminescence properties of micro- or nano-crystals and for extending their application. - Highlights: • Single LiYF 4 microparticle is excited with IR laser at 980 nm in a confocal setup, and strong green and weak red emissions are observed. • Single LiYF 4 microparticle with different morphology exhibits different fluorescence emission intensity and intensity ratio of red to green emission. • The possible mechanism, the influence of particle size and the existence of EDTA on the upconversion emission are investigated

  17. Identification of second harmonic optical effects from vaccine coated gold microparticles

    International Nuclear Information System (INIS)

    Jumah, N A; Ameer-Beg, S M; White, N S; Prasad, K V R; Bellhouse, B J

    2004-01-01

    This study investigates the optical effects observed from uncoated and protein vaccine coated gold microparticles while imaging with two-photon excitation in the Mie scattering regime. When observed with time correlated single photon counting fluorescence lifetime microscopy, the emission from the gold microparticles appeared as an intense instrument-limited temporal response. The intensity of the emission showed a second-order dependence on the laser power and frequency doubling of the emitted light was observed for fundamental light between 890 and 970 nm. The optical effect was attributed to two-photon induced second harmonic generation. The vaccine coated gold microparticles had a much weaker second harmonic signal than the uncoated gold microparticles. Chemical analysis of the surface of the gold microparticles revealed that the vaccine coating decreases the surface charge thereby diminishing the observed second harmonic signal. These optical properties can be exploited to identify both the location of the protein vaccine coating as well as the gold microparticles in vitro and potentially to investigate the vaccine delivery kinetics in vivo

  18. Functionalized Raspberry-Like Microparticles obtained by Assembly of Nanoparticles during Electrospraying

    International Nuclear Information System (INIS)

    Cho, Eun Chul; Jeong, Unyong; Hwang, Yoon Kyun

    2014-01-01

    The present study suggests a novel method to produce raspberry-like microparticles containing diverse functional materials inside. The raspberry-like microparticles were produced from a random assembly of uniformly-sized poly(methyl methacrylate) (PMMA) nanoparticles via electrospraying. The solution containing the PMMA nanoparticles were supplied through the inner nozzle and compressed air was emitted through the outer nozzle. The air supply helped fast evaporation of acetone, so it enabled copious amount of microparticles as dry powder. The microparticles were highly porous both on the surface and interiors, hence various materials with a function of UV-blocking (TiO 2 nanoparticles and methoxyphenyl triazine) or anti-aging (ethyl(4-(2,3-dihydro-1H-indene-5-carboxyamido) benzoate)) were loaded in large amount (17 wt % versus PMMA). The surface and interior structures of the microparticles were dependent on the characteristics of functional materials. The results clearly suggest that the process to prepare the raspberry-like microparticles can be an excellent approach to generate functional microstructures

  19. Physical Characterization of Mouse Deep Vein Thrombosis Derived Microparticles by Differential Filtration with Nanopore Filters

    Directory of Open Access Journals (Sweden)

    Antonio Peramo

    2011-12-01

    Full Text Available With the objective of making advancements in the area of pro-thrombotic microparticle characterization in cardiovascular biology, we present a novel method to separate blood circulating microparticles using a membrane-based, nanopore filtration system. In this qualitative study, electron microscopy observations of these pro-thrombotic mouse microparticles, as well as mouse platelets and leukocytes obtained using a mouse inferior vena cava ligation model of deep-vein thrombosis are presented. In particular, we present mouse microparticle morphology and microstructure using SEM and TEM indicating that they appear to be mostly spherical with diameters in the 100 to 350 nm range. The nanopore filtration technique presented is focused on the development of novel methodologies to isolate and characterize blood circulating microparticles that can be used in conjunction with other methodologies. We believe that determination of microparticle size and structure is a critical step for the development of reliable assays with clinical or research application in thrombosis and it will contribute to the field of nanomedicine in thrombosis.

  20. Chitosan-modified porous silicon microparticles for enhanced permeability of insulin across intestinal cell monolayers.

    Science.gov (United States)

    Shrestha, Neha; Shahbazi, Mohammad-Ali; Araújo, Francisca; Zhang, Hongbo; Mäkilä, Ermei M; Kauppila, Jussi; Sarmento, Bruno; Salonen, Jarno J; Hirvonen, Jouni T; Santos, Hélder A

    2014-08-01

    Porous silicon (PSi) based particulate systems are emerging as an important drug delivery system due to its advantageous properties such as biocompatibility, biodegradability and ability to tailor the particles' physicochemical properties. Here, annealed thermally hydrocarbonized PSi (AnnTHCPSi) and undecylenic acid modified AnnTHCPSi (AnnUnTHCPSi) microparticles were developed as a PSi-based platform for oral delivery of insulin. Chitosan (CS) was used to modify the AnnUnTHCPSi microparticles to enhance the intestinal permeation of insulin. Surface modification with CS led to significant increase in the interaction of PSi microparticles with Caco-2/HT-29 cell co-culture monolayers. Compared to pure insulin, the CS-conjugated microparticles significantly improved the permeation of insulin across the Caco-2/HT-29 cell monolayers, with ca. 20-fold increase in the amount of insulin permeated and ca. 7-fold increase in the apparent permeability (P(app)) value. Moreover, among all the investigated particles, the CS-conjugated microparticles also showed the highest amount of insulin associated with the mucus layer and the intestinal Caco-2 cells and mucus secreting HT-29 cells. Our results demonstrate that CS-conjugated AnnUnTHCPSi microparticles can efficiently enhance the insulin absorption across intestinal cells, and thus, they are promising microsystems for the oral delivery of proteins and peptides across the intestinal cell membrane. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Cutting-edge analysis of extracellular microparticles using ImageStream(X) imaging flow cytometry.

    Science.gov (United States)

    Headland, Sarah E; Jones, Hefin R; D'Sa, Adelina S V; Perretti, Mauro; Norling, Lucy V

    2014-06-10

    Interest in extracellular vesicle biology has exploded in the past decade, since these microstructures seem endowed with multiple roles, from blood coagulation to inter-cellular communication in pathophysiology. In order for microparticle research to evolve as a preclinical and clinical tool, accurate quantification of microparticle levels is a fundamental requirement, but their size and the complexity of sample fluids present major technical challenges. Flow cytometry is commonly used, but suffers from low sensitivity and accuracy. Use of Amnis ImageStream(X) Mk II imaging flow cytometer afforded accurate analysis of calibration beads ranging from 1 μm to 20 nm; and microparticles, which could be observed and quantified in whole blood, platelet-rich and platelet-free plasma and in leukocyte supernatants. Another advantage was the minimal sample preparation and volume required. Use of this high throughput analyzer allowed simultaneous phenotypic definition of the parent cells and offspring microparticles along with real time microparticle generation kinetics. With the current paucity of reliable techniques for the analysis of microparticles, we propose that the ImageStream(X) could be used effectively to advance this scientific field.

  2. Raman Spectroscopy of Optically Trapped Single Biological Micro-Particles

    Science.gov (United States)

    Redding, Brandon; Schwab, Mark J.; Pan, Yong-le

    2015-01-01

    The combination of optical trapping with Raman spectroscopy provides a powerful method for the study, characterization, and identification of biological micro-particles. In essence, optical trapping helps to overcome the limitation imposed by the relative inefficiency of the Raman scattering process. This allows Raman spectroscopy to be applied to individual biological particles in air and in liquid, providing the potential for particle identification with high specificity, longitudinal studies of changes in particle composition, and characterization of the heterogeneity of individual particles in a population. In this review, we introduce the techniques used to integrate Raman spectroscopy with optical trapping in order to study individual biological particles in liquid and air. We then provide an overview of some of the most promising applications of this technique, highlighting the unique types of measurements enabled by the combination of Raman spectroscopy with optical trapping. Finally, we present a brief discussion of future research directions in the field. PMID:26247952

  3. Quantitative proteome profiling of normal human circulating microparticles

    DEFF Research Database (Denmark)

    Østergaard, Ole; Nielsen, Christoffer T; Iversen, Line V

    2012-01-01

    Circulating microparticles (MPs) are produced as part of normal physiology. Their numbers, origin, and composition change in pathology. Despite this, the normal MP proteome has not yet been characterized with standardized high-resolution methods. We here quantitatively profile the normal MP...... proteome using nano-LC-MS/MS on an LTQ-Orbitrap with optimized sample collection, preparation, and analysis of 12 different normal samples. Analytical and procedural variation were estimated in triply processed samples analyzed in triplicate from two different donors. Label-free quantitation was validated...... by the correlation of cytoskeletal protein intensities with MP numbers obtained by flow cytometry. Finally, the validity of using pooled samples was evaluated using overlap protein identification numbers and multivariate data analysis. Using conservative parameters, 536 different unique proteins were quantitated...

  4. Fabrication of fillable microparticles and other complex 3D microstructures

    Science.gov (United States)

    McHugh, Kevin J.; Nguyen, Thanh D.; Linehan, Allison R.; Yang, David; Behrens, Adam M.; Rose, Sviatlana; Tochka, Zachary L.; Tzeng, Stephany Y.; Norman, James J.; Anselmo, Aaron C.; Xu, Xian; Tomasic, Stephanie; Taylor, Matthew A.; Lu, Jennifer; Guarecuco, Rohiverth; Langer, Robert; Jaklenec, Ana

    2017-09-01

    Three-dimensional (3D) microstructures created by microfabrication and additive manufacturing have demonstrated value across a number of fields, ranging from biomedicine to microelectronics. However, the techniques used to create these devices each have their own characteristic set of advantages and limitations with regards to resolution, material compatibility, and geometrical constraints that determine the types of microstructures that can be formed. We describe a microfabrication method, termed StampEd Assembly of polymer Layers (SEAL), and create injectable pulsatile drug-delivery microparticles, pH sensors, and 3D microfluidic devices that we could not produce using traditional 3D printing. SEAL allows us to generate microstructures with complex geometry at high resolution, produce fully enclosed internal cavities containing a solid or liquid, and use potentially any thermoplastic material without processing additives.

  5. Micro-particles in ITER: A comprehensive review

    International Nuclear Information System (INIS)

    Grisolia, C.; Rosanvallon, S.; Sharpe, Ph.; Winter, J.

    2009-01-01

    In a fusion reactor like ITER, in-vessel materials are subjected to interactions with the plasma. One of the main consequences of these plasma-material interactions is the creation of co-deposited layers. Due to internal stresses, part of these layers can crack leading to micro particle creation. The purpose of the following paper is to review the Tokamak operation processes which lead to erosion and layer creation. Then, the proportion of these layers that is converted into micro-particles will be evaluated in the case of Tore Supra experiments and extrapolated for ITER. It is major importance to measure the ITER mobilizable dusts present in the Vacuum Vessel and compare the measured quantity with the safety limits. When approaching these limits, removal systems must be used in order to control the in-vessel dust inventory. In the second part of the paper, diagnostics and removal system under development will be presented.

  6. Observation of Various and Spontaneous Magnetic Skyrmionic Bubbles at Room Temperature in a Frustrated Kagome Magnet with Uniaxial Magnetic Anisotropy

    KAUST Repository

    Hou, Zhipeng; Ren, Weijun; Ding, Bei; Xu, Guizhou; Wang, Yue; Yang, Bing; Zhang, Qiang; Zhang, Ying; Liu, Enke; Xu, Feng; Wang, Wenhong; Wu, Guangheng; Zhang, Xixiang; Shen, Baogen; Zhang, Zhidong

    2017-01-01

    to various external stimuli acting as information carriers in spintronic devices. Here, the first observation of skyrmionic magnetic bubbles with variable topological spin textures formed at room temperature in a frustrated kagome Fe3 Sn2 magnet with uniaxial

  7. Precipitation of fluticasone propionate microparticles using supercritical antisolvent

    Directory of Open Access Journals (Sweden)

    A Vatanara

    2009-03-01

    Full Text Available ABSTRACT Background: The ability of supercritical fluids (SCFs, such as carbon dioxide, to dissolve and expand or extract organic solvents and as result lower their solvation power, makes it possible the use of SCFs for the precipitation of solids from organic solutions. The process could be the injection of a solution of the substrate in an organic solvent into a vessel which is swept by a supercritical fluid. The aim of this study was to ascertain the feasibility of supercritical processing to prepare different particulate forms of fluticasone propionate (FP, and to evaluate the influence of different liquid solvents and precipitation temperatures on the morphology, size and crystal habit of particles. Method: The solution of FP in organic solvents, was precipitated by supercritical carbon dioxide (SCCO2 at two pressure and temperature levels. Effects of process parameters on the physicochemical characteristics of harvested microparticles were evaluated. Results: Particle formation was observed only at the lower selected pressure, whilst at the higher pressure, no precipitation of particles was occurred due to dissolution of FP in supercritical antisolvent. The micrographs of the produced particles showed different morphologies for FP obtained from different conditions. The results of thermal analysis of the resulted particles showed that changes in the processing conditions didn't influence thermal behavior of the precipitated particles. Evaluation of the effect of temperature on the size distribution of particles showed that increase in the temperature from 40 oC to 50 oC, resulted in reduction of the mean particle size from about 30 µm to about 12 μm. ‍Conclusion: From the results of this study it may be concluded that, processing of FP by supercritical antisolvent could be an approach for production of diverse forms of the drug and drastic changes in the physical characteristics of microparticles could be achieved by changing the

  8. Carbon monoxide inhalation increases microparticles causing vascular and CNS dysfunction

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jiajun; Yang, Ming [Department of Emergency Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104 (United States); Kosterin, Paul [Department of Neuroscience, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104 (United States); Salzberg, Brian M. [Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104 (United States); Milovanova, Tatyana N.; Bhopale, Veena M. [Department of Emergency Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104 (United States); Thom, Stephen R., E-mail: sthom@smail.umaryland.edu [Department of Emergency Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104 (United States)

    2013-12-01

    We hypothesized that circulating microparticles (MPs) play a role in pro-inflammatory effects associated with carbon monoxide (CO) inhalation. Mice exposed for 1 h to 100 ppm CO or more exhibit increases in circulating MPs derived from a variety of vascular cells as well as neutrophil activation. Tissue injury was quantified as 2000 kDa dextran leakage from vessels and as neutrophil sequestration in the brain and skeletal muscle; and central nervous system nerve dysfunction was documented as broadening of the neurohypophysial action potential (AP). Indices of injury occurred following exposures to 1000 ppm for 1 h or to 1000 ppm for 40 min followed by 3000 ppm for 20 min. MPs were implicated in causing injuries because infusing the surfactant MP lytic agent, polyethylene glycol telomere B (PEGtB) abrogated elevations in MPs, vascular leak, neutrophil sequestration and AP prolongation. These manifestations of tissue injury also did not occur in mice lacking myeloperoxidase. Vascular leakage and AP prolongation were produced in naïve mice infused with MPs that had been obtained from CO poisoned mice, but this did not occur with MPs obtained from control mice. We conclude that CO poisoning triggers elevations of MPs that activate neutrophils which subsequently cause tissue injuries. - Highlights: • Circulating microparticles (MPs) increase in mice exposed to 100 ppm CO or more. • MPs are lysed by infusing the surfactant polyethylene glycol telomere B. • CO-induced MPs cause neutrophil activation, vascular leak and CNS dysfunction. • Similar tissue injuries do not arise with MPs obtained from air-exposed, control mice.

  9. Influence of red blood cell-derived microparticles upon vasoregulation.

    Science.gov (United States)

    Said, Ahmed S; Doctor, Allan

    2017-10-01

    Here we review recent data and the evolving understanding of the role of red blood cell-derived microparticles (RMPs) in normal physiology and in disease progression. Microparticles (MPs) are small membrane vesicles derived from various parent cell types. MPs are produced in response to a variety of stimuli through several cytoskeletal and membrane phospholipid changes. MPs have been investigated as potential biomarkers for multiple disease processes and are thought to have biological effects, most notably in: promotion of coagulation, production and handling of reactive oxygen species, immune modulation, angiogenesis, and in apoptosis. Specifically, RMPs are produced normally during RBC maturation and their production is accelerated during processing and storage for transfusion. Several factors during RBC storage are known to trigger RMP production, including: increased intracellular calcium, increased potassium leakage, and energy failure with ATP depletion. Of note, RMP composition differs from that of intact RBCs, and the nature and composition of RMP components are affected by both storage duration and the character of storage solutions. Recognised RMP bioactivities include: promotion of coagulation, immune modulation, and promotion of endothelial adhesion, as well as influence upon vasoregulation via nitric oxide (NO) scavenging. Of particular relevance, RMPs are more avid NO scavengers than intact RBCs and this feature has been proposed as a mechanism for the impaired oxygen delivery homeostasis that has been observed following transfusion. Preliminary human studies demonstrate that circulating RMP abundance increases with RBC transfusion and is associated with altered plasma vasoactivity and abnormal vasoregulation. In summary, RMPs are submicron particles released from stored RBCs, with demonstrated vasoactive properties that appear to disturb oxygen delivery homeostasis. The clinical impact of RMPs in transfusion recipients is an area of continued

  10. Preparation of Starch/Gelatin Blend Microparticles by a Water-in-Oil Emulsion Method for Controlled Release Drug Delivery

    OpenAIRE

    Phromsopha, Theeraphol; Baimark, Yodthong

    2014-01-01

    Information on the preparation and properties of starch/gelatin blend microparticles with and without crosslinking for drug delivery is presented. The blend microparticles were prepared by the water-in-oil emulsion solvent diffusion method. Glutaraldehyde and methylene blue were used as the crosslinker and the water-soluble drug model, respectively. The blend microparticles were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and UV-Vis spe...

  11. Circulating levels of cell-derived microparticles are reduced by mild hypobaric hypoxia: data from a randomised controlled trial.

    Science.gov (United States)

    Ayers, Lisa; Stoewhas, Anne-Christin; Ferry, Berne; Latshang, Tsogyal D; Lo Cascio, Christian M; Sadler, Ross; Stadelmann, Katrin; Tesler, Noemi; Huber, Reto; Achermann, Peter; Bloch, Konrad E; Kohler, Malcolm

    2014-05-01

    Hypoxia is known to induce the release of microparticles in vitro. However, few publications have addressed the role of hypoxia in vivo on circulating levels of microparticles. This randomised, controlled, crossover trial aimed to determine the effect of mild hypoxia on in vivo levels of circulating microparticles in healthy individuals. Blood was obtained from 51 healthy male volunteers (mean age of 26.9 years) at baseline altitude (490 m) and after 24 and 48 h at moderate altitude (2,590 m). The order of altitude exposure was randomised. Flow cytometry was used to assess platelet-poor plasma for levels of circulating microparticles derived from platelets, endothelial cells, leucocytes, granulocytes, monocytes, red blood cells and procoagulant microparticles. Mean (standard deviation) oxygen saturation was significantly lower on the first and second day after arrival at 2,590 m, 91.0 (2.0) and 92.0 (2.0) %, respectively, compared to 490 m, 96 (1.0) %, p microparticles (annexin V+ -221/μl 95 % CI -370.8/-119.0, lactadherin+ -202/μl 95 % CI -372.2/-93.1), platelet-derived microparticles (-114/μl 95 % CI -189.9/-51.0) and red blood cell-derived microparticles (-81.4 μl 95 % CI -109.9/-57.7) after 48 h at moderate altitude was found. Microparticles derived from endothelial cells, granulocytes, monocytes and leucocytes were not significantly altered by exposure to moderate altitude. In healthy male individuals, mild hypobaric hypoxia, induced by a short-term stay at moderate altitude, is associated with lower levels of procoagulant microparticles, platelet-derived microparticles and red blood cell-derived microparticles, suggesting a reduction in thrombotic potential.

  12. Maintainable substrate carrier for electroplating

    Science.gov (United States)

    Chen, Chen-An [Milpitas, CA; Abas, Emmanuel Chua [Laguna, PH; Divino, Edmundo Anida [Cavite, PH; Ermita, Jake Randal G [Laguna, PH; Capulong, Jose Francisco S [Laguna, PH; Castillo, Arnold Villamor [Batangas, PH; Ma,; Xiaobing, Diana [Saratoga, CA

    2012-07-17

    One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The carrier includes a non-conductive carrier body on which the substrates are placed and conductive lines embedded within the carrier body. A plurality of conductive clip attachment parts are attached in a permanent manner to the conductive lines embedded within the carrier body. A plurality of contact clips are attached in a removable manner to the clip attachment parts. The contact clips hold the substrates in place and conductively connecting the substrates with the conductive lines. Other embodiments, aspects and features are also disclosed.

  13. Controlled release of beta-estradiol from PLAGA microparticles: the effect of organic phase solvent on encapsulation and release.

    Science.gov (United States)

    Birnbaum, D T; Kosmala, J D; Henthorn, D B; Brannon-Peppas, L

    2000-04-03

    To determine the effect of the organic solvent used during microparticle preparation on the in vitro release of beta-estradiol, a number of formulations were evaluated in terms of size, shape and drug delivery performance. Biodegradable microparticles of poly(lactide-co-glycolide) were prepared containing beta-estradiol that utilized dichloromethane, ethyl acetate or a mixture of dichloromethane and methanol as the organic phase solvent during the particle preparation. The drug delivery behavior from the microparticles was studied and comparisons were made of their physical properties for different formulations. The varying solubilities of beta-estradiol and poly(lactide-co-glycolide) in the solvents studied resulted in biodegradable microparticles with very different physical characteristics. Microparticles prepared from solid suspensions of beta-estradiol using dichloromethane as the organic phase solvent were similar in appearance to microparticles prepared without drug. Microparticles prepared from dichloromethane/methanol solutions appeared transparent to translucent depending on the initial amount of drug used in the formulation. Microparticles prepared using ethyl acetate appeared to have the most homogeneous encapsulation of beta-estradiol, appearing as solid white spheres regardless of initial drug content. Studies showed that microparticles prepared from either ethyl acetate or a mixture of dichloromethane and methanol gave a more constant release profile of beta-estradiol than particles prepared using dichloromethane alone. For all formulations, an initial burst of release increased with increasing drug loading, regardless of the organic solvent used.

  14. A Comparison of Aerosolization and Homogenization Techniques for Production of Alginate Microparticles for Delivery of Corticosteroids to the Colon.

    Science.gov (United States)

    Samak, Yassmin O; El Massik, Magda; Coombes, Allan G A

    2017-01-01

    Alginate microparticles incorporating hydrocortisone hemisuccinate were produced by aerosolization and homogenization methods to investigate their potential for colonic drug delivery. Microparticle stabilization was achieved by CaCl 2 crosslinking solution (0.5 M and 1 M), and drug loading was accomplished by diffusion into blank microparticles or by direct encapsulation. Homogenization method produced smaller microparticles (45-50 μm), compared to aerosolization (65-90 μm). High drug loadings (40% wt/wt) were obtained for diffusion-loaded aerosolized microparticles. Aerosolized microparticles suppressed drug release in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) prior to drug release in simulated colonic fluid (SCF) to a higher extent than homogenized microparticles. Microparticles prepared using aerosolization or homogenization (1 M CaCl 2 , diffusion loaded) released 5% and 17% of drug content after 2 h in SGF and 4 h in SIF, respectively, and 75% after 12 h in SCF. Thus, aerosolization and homogenization techniques show potential for producing alginate microparticles for colonic drug delivery in the treatment of inflammatory bowel disease. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  15. Polyelectrolyte microparticles for enhancing anode performance in an air–cathode μ-Liter microbial fuel cell

    International Nuclear Information System (INIS)

    Chen, Yan-Yu; Wang, Hsiang-Yu

    2015-01-01

    Highlights: • Microparticles with high consistency and surface area per volume are fabricated. • P(DADMAC) microparticles facilitate microorganism accumulation and charge transfer. • Microbes in microparticles are capable of proliferation and electricity generation. • Microparticles increase limiting current/power output to more than 200% of biofilm. • Microparticles decrease the anode charge-transfer resistance to 44% of biofilm. - Abstract: Microbial fuel cell (MFC) is considered an environmentally friendly energy source because it generates electrical power by digesting organic substrates in the wastewater. However, it is still challenging for MFC to become an economically affordable and highly efficient energy source due to its relatively low power output and coulombic efficiency. The aim of this study is to increase the performance of anode by using polyelectrolyte microparticles to facilitate the accumulation of microorganisms and the collection of electrons. The polyelectrolyte microparticle is subjected to microscopy, cyclic voltammetry, electrochemical impedance spectroscopy and continuous electricity generation in an air–cathode μ-Liter MFC (μMFC) to validate its biocompatibility, ability in retaining redox species, reduced electron transfer resistance, and sustained energy generation. During the 168-hour operation, microorganisms proliferate inside the microparticle and generate around 250% power output and 200% limiting current of those from microorganism biofilm. The polyelectrolyte microparticle also decreased charge-transfer resistance of anode electrode in air–cathode μMFC by 56% compared with biofilm.

  16. Systems and methods for creation of conducting networks of magnetic particles through dynamic self-assembly process

    Science.gov (United States)

    Snezhko, Oleksiy [Woodridge, IL; Aronson, Igor [Darien, IL; Kwok, Wai-Kwong [Downers Grove, IL

    2011-01-25

    Self-assembly of magnetic microparticles in AC magnetic fields. Excitation of the system by an AC magnetic field provides a variety of patterns that can be controlled by adjusting the frequency and the amplitude of the field. At low particle densities the low-frequency magnetic excitation favors cluster phase formation, while high frequency excitation favors chains and netlike structures. For denser configurations, an abrupt transition to the network phase was obtained.

  17. Autonomous component carrier selection

    DEFF Research Database (Denmark)

    Garcia, Luis Guilherme Uzeda; Pedersen, Klaus; Mogensen, Preben

    2009-01-01

    management and efficient system operation. Due to the expected large number of user-deployed cells, centralized network planning becomes unpractical and new scalable alternatives must be sought. In this article, we propose a fully distributed and scalable solution to the interference management problem...... in local areas, basing our study case on LTE-Advanced. We present extensive network simulation results to demonstrate that a simple and robust interference management scheme, called autonomous component carrier selection allows each cell to select the most attractive frequency configuration; improving...... the experience of all users and not just the few best ones; while overall cell capacity is not compromised....

  18. Microparticles containing guaraná extract obtained by spray-drying technique: development and characterization

    Directory of Open Access Journals (Sweden)

    Traudi Klein

    Full Text Available AbstractGuaraná (Paullinia cupana Kunth, Sapindaceae is well known for its dietary and pharmaceutical potential, and the semipurified extract of guaraná shows antidepressant and panicolytic effects. However, the low solubility, bioavailability and stability of the semipurified extract limit its use as a component of pharmaceutical agents. Delivery of the semipurified extract in a microparticle form could help to optimize its stability. In this study, microparticles containing semipurified extract of guaraná were obtained by the spray-drying technique, using a combination of maltodextrin and gum arabic. The raw materials and microparticles produced were characterized by particle size analysis, differential scanning calorimetry, thermogravimetric analysis, and scanning electron microscopy. The drug content and antioxidant capacity were also evaluated. In vitrodissolution tests using flow cell dissolution apparatus, were carried out to investigate the influence of formulation parameters on the release of semipurified extract of guaraná from the microparticles. The spray-drying technique and the processing conditions selected gave satisfactory encapsulation efficiency (80–110% and product yield (55–60%. The mean diameter of microparticles was around 4.5 µm. The DPPH radical scavenging capacity demonstrated that microparticles can protect the semipurified extract of guaraná from the effect of high temperatures during the process maintained the antioxidant capacity. Differential scanning calorimetry results indicated an interaction between semipurified extract of guaraná and gum arabic: maltodextrin in the microparticles, and thermogravimetric analysis indicate that the profile curves of the microparticles are similar to the adjuvants used in drying, probably due to the higher proportion of adjuvants compared to semipurified extract of guaraná. In vitro dissolution tests demonstrate that all formulations complete dissolution within 60 min

  19. Enhanced bioavailability and anthelmintic efficacy of mebendazole in redispersible microparticles with low-substituted hydroxypropylcellulose

    Directory of Open Access Journals (Sweden)

    Torre-Iglesias PM

    2014-09-01

    Full Text Available Paloma Marina de la Torre-Iglesias,1,2 Juan José García-Rodriguez,3 Guillermo Torrado,4 Susana Torrado,1,2 Santiago Torrado-Santiago,1,5 Francisco Bolás-Fernández3 1Department of Pharmaceutical Technology, Faculty of Pharmacy, Complutense University, Madrid, Spain; 2Institute of Industrial Pharmacy, Complutense University, Madrid, Spain; 3Department of Parasitology, Faculty of Pharmacy, Complutense University, Madrid, Spain; 4Department of Pharmaceutical Technology, Faculty of Pharmacy, Alcala University, Alcala de Henares (Madrid, Spain; 5Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD, Madrid, Spain Background: Mebendazole (MBZ is an extremely insoluble and therefore poorly absorbed drug and the variable clinical results may correlate with blood concentrations. The necessity of a prolonged high dose treatment of this drug increases the risk of adverse effects. Methods: In the present study we prepared redispersible microparticles (RDM containing MBZ, an oral, poorly water-soluble drug, in different proportions of low-substituted hydroxypropylcellulose (L-HPC. We investigated the microparticulate structures that emerge spontaneously upon dispersion of an RDM in aqueous medium and elucidated their influence on dissolution, and also on their oral bioavailability and therapeutic efficiency using a murine model of infection with the nematode parasite Trichinella spiralis.Results: Elevated percentages of dissolved drug were obtained with RDM at 1:2.5 and 1:5 ratios of MBZ: L-HPC. Thermal analysis showed an amorphization of MBZ in the RDM by the absence of a clear MBZ melting peak in formulations. The rapid dissolution behavior could be due to the decreased drug crystallinity, the fast dissolution time of carriers as L-HPC, together with its superior dispersibility and excellent wetting properties. RDM-1:2.5 and RDM-1:5 resulted in increased maximum plasma concentration and area(s under the curve (AUC0

  20. Preparation of bovine serum albumin hollow microparticles by the water-in-oil emulsion solvent diffusion technique for drug delivery applications

    International Nuclear Information System (INIS)

    Baimark, Y.; Srisa-Ard, M.; Srihaman, P.

    2012-01-01

    Biodegradable bovine serum albumin (BSA) hollow microparticles have been prepared by a single step and rapid water-in-oil emulsion solvent diffusion method without any emulsifiers and templates. Aqueous BSA solution and ethyl acetate were used as water and oil phases, respectively. BSA solution was cross-linked with polyethylene glycol diglycidyl ether (PEGDE) before microparticle formation. Methylene blue (MB) was used as a water-soluble model drug to entrap in the microparticle matrix. The non-cross-linked and cross-linked BSA microparticles contained empty core structure with outer smooth surface. Inner surface and matrix of hollow microparticles consisted void structure. Drug loading did not affect the microparticle morphology. Cumulative drug released from microparticles was decreased steadily as decreasing of MB ratio and increasing of PEGDE ratio. The BSA hollow microparticles may have potential application in controlled release drug delivery application. (author)

  1. Size-controlled fabrication of zein nano/microparticles by modified anti-solvent precipitation with/without sodium caseinate.

    Science.gov (United States)

    Li, Feng; Chen, Yan; Liu, Shubo; Qi, Jian; Wang, Weiying; Wang, Chenhua; Zhong, Ruiyue; Chen, Zhijun; Li, Xiaoming; Guan, Yuanzhou; Kong, Wei; Zhang, Yong

    2017-01-01

    Zein-based nano/microparticles have been demonstrated to be promising carrier systems for both the food industry and biomedical applications. However, the fabrication of size-controlled zein particles has been a challenging issue. In this study, a modified anti-solvent precipitation method was developed, and the effects of various factors, such as mixing method, solvent/anti-solvent ratio, temperature, zein concentrations and the presence of sodium caseinate (SC) on properties of zein particles were investigated. Evidence is presented that, among the previously mentioned factors, the mixing method, especially mixing rate, could be used as an effective parameter to control the size of zein particles without changing other parameters. Moreover, through fine-tuning the mixing rate together with zein concentration, particles with sizes ranging from nanometers to micrometers and low polydispersity index values could be easily obtained. Based on the size-controlled fabrication method, SC-coated zein nanoparticles could also be obtained in a size-controlled manner by incubation of the coating material with the already-formed zein particles. The resultant nanoparticles showed better performance in both drug loading and controlled release, compared with zein/SC hybrid nanoparticles fabricated by adding aqueous ethanol solution to SC solution. The possible mechanisms of the nanoprecipitation process and self-assembly formation of these nanoparticles are discussed.

  2. 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.

  3. External and Intraparticle Diffusion of Coumarin 102 with Surfactant in the ODS-silica Gel/water System by Single Microparticle Injection and Confocal Fluorescence Microspectroscopy

    OpenAIRE

    NAKATANI, Kiyoharu; MATSUTA, Emi

    2015-01-01

    The release mechanism of coumarin 102 from a single ODS-silica gel microparticle into the water phase in the presence of Triton X-100 was investigated by confocal fluorescence microspectroscopy combined with the single microparticle injection technique. The release rate significantly depended on the Triton X-100 concentration in the water phase and was not limited by diffusion in the pores of the microparticle. The release rate constant was inversely proportional to the microparticle radius s...

  4. Micro-particle transporting system using galvanotactically stimulated apo-symbiotic cells of Paramecium bursaria.

    Science.gov (United States)

    Furukawa, Shunsuke; Karaki, Chiaki; Kawano, Tomonori

    2009-01-01

    It is well known that Paramecium species including green paramecia (Paramecium bursaria) migrate towards the anode when exposed to an electric field in a medium. This type of a cellular movement is known as galvanotaxis. Our previous study revealed that an electric stimulus given to P bursaria is converted to a galvanotactic cellular movement by involvement of T-type calcium channel on the plasma membrane [Aonuma et al. (2007), Z. Naturforsch. 62c, 93-102]. This phenomenon has attracted the attention of bioengineers in the fields of biorobotics or micro-robotics in order to develop electrically controllable micromachineries. Here, we demonstrate the galvanotactic controls of the cellular migration of P bursaria in capillary tubes (diameter, 1-2 mm; length, 30-240 mm). Since the Paramecium cells take up particles of various sizes, we attempted to use the electrically stimulated cells of P bursaria as the vehicle for transportation of micro-particles in the capillary system. By using apo-symbiotic cells of P bursaria obtained after forced removal of symbiotic algae, the uptake of the particles could be maximized and visualized. Then, electrically controlled transportations of particle-filled apo-symbiotic P bursaria cells were manifested. The particles transported by electrically controlled cells (varying in size from nm to /m levels) included re-introduced green algae, fluorescence-labeled polystyrene beads, magnetic microspheres, emerald green fluorescent protein (EmGFP)-labeled cells of E. coli, Indian ink, and crystals of zeolite (hydrated aluminosilicate minerals with a micro-porous structure) and some metal oxides. Since the above demonstrations were successful, we concluded that P bursaria has a potential to be employed as one of the micro-biorobotic devices used in BioMEMS (biological micro-electro-mechanical systems).

  5. LIQUIFIED NATURAL GAS (LNG CARRIERS

    Directory of Open Access Journals (Sweden)

    Daniel Posavec

    2010-12-01

    Full Text Available Modern liquefied natural gas carriers are double-bottom ships classified according to the type of LNG tank. The tanks are specially designed to store natural gas cooled to -161°C, the boiling point of methane. Since LNG is highly flammable, special care must be taken when designing and operating the ship. The development of LNG carriers has begun in the middle of the twentieth century. LNG carrier storage space has gradually grown to the current maximum of 260000 m3. There are more than 300 LNG carriers currently in operation (the paper is published in Croatian.

  6. 77 FR 42548 - Privacy Act of 1974; Department of Transportation, Federal Motor Carrier Safety Administration...

    Science.gov (United States)

    2012-07-19

    ... motor carrier business models which may include the use of industry service providers to directly hire... in secure facilities. Electronic records may be stored on magnetic disc, tape, digital media, and CD...

  7. An experimental comparison of path planning techniques applied to micro-sized magnetic agents

    NARCIS (Netherlands)

    Scheggi, Stefano; Misra, Sarthak; Haliyo, S.; Sill, A.; Regnier, S.; Fatikow, S.

    2016-01-01

    Micro-sized agents can be used in applications suchas microassembly, micromanipulation, and minimally invasive surgeries. Magnetic agents such as paramagnetic microparticles can be controlled to deliver pharmaceutical agents to difficult-toaccess regions within the human body. In order to

  8. Development of thiolated poly(acrylic acid) microparticles for the nasal administration of exenatide.

    Science.gov (United States)

    Millotti, Gioconda; Vetter, Anja; Leithner, Katharina; Sarti, Federica; Shahnaz Bano, Gul; Augustijns, Patrick; Bernkop-Schnürch, Andreas

    2014-12-01

    The purpose of this study was to develop a microparticulate formulation for nasal delivery of exenatide utilizing a thiolated polymer. Poly(acrylic acid)-cysteine (PAA-cys) and unmodified PAA microparticles loaded with exenatide were prepared via coprecipitation of the drug and the polymer followed by micronization. Particle size, drug load and release of incorporated exenatide were evaluated. Permeation enhancing properties of the formulations were investigated on excised porcine respiratory mucosa. The viability of the mucosa was investigated by histological studies. Furthermore, ciliary beat frequency (CBF) studies were performed. Microparticles displayed a mean size of 70-80 µm. Drug encapsulation was ∼80% for both thiolated and non-thiolated microparticles. Exenatide was released from both thiolated and non-thiolated particles in comparison to exenatide in buffer only within 40 min. As compared to exenatide dissolved in buffer only, non-thiolated and thiolated microparticles resulted in a 2.6- and 4.7-fold uptake, respectively. Histological studies performed before and after permeation studies showed that the mucosa is not damaged during permeation studies. CBF studies showed that the formulations were cilio-friendly. Based on these results, poly(acrylic acid)-cysteine-based microparticles seem to be a promising approach starting point for the nasal delivery of exenatide.

  9. Heparin induced alterations in clearance and distribution of blood-borne microparticles following operative trauma.

    Science.gov (United States)

    Saba, T M; Antikatzides, T G

    1979-04-01

    The influence of systemic heparin administration on the vascular clearance and tissue distribution of blood-borne microparticles was evaluated in normal rats and rats after operation (laparotomy plus intestinal manipulation) utilizing an (131)I- colloid which is phagocytized by the reticuloendothelial system (RES). Intravenous heparin administration (100 USP/100g body weight) into normal animals three minutes prior to colloid injection (50 mg/lOOg) induced a significant increase in pulmonary localization of the microparticles as compared to nonheparinized control rats, while hepatic and splenic uptake were decreased. Surgical trauma decreased hepatic RE uptake and increased pulmonary localization of the microparticles when injected systemically at 60 minutes postsurgery. Heparin administration 60 minutes after surgery and three minutes prior to colloid injection, magnified the increased pulmonary localization response with an associated further depression of the RES. The ability of heparin to alter both RE clearance function and lung localization of microparticles was dose dependent and a function of the interval between heparin administration and systemic particulate infusion. Thus, low dose heparin administration was capable of stimulating RE activity while heparin in doses of excess of 50 USP units/lOOg body weight decreased RE function. These findings suggest that the functional state of the hepatic RE system can be greatly affected in a dose-dependent manner by systemic heparin administration which may influence distribution of blood-borne microparticles.

  10. Formulation and Evaluation of Organogels Containing Hyaluronan Microparticles for Topical Delivery of Caffeine.

    Science.gov (United States)

    Simsolo, Erol Eli; Eroğlu, İpek; Tanrıverdi, Sakine Tuncay; Özer, Özgen

    2018-04-01

    Cellulite is a dermal disorder including the extracellular matrix, the lymphatic and microcirculatory systems and the adipose tissue. Caffeine is used as the active moiety depending its preventive effect on localization of fat in the cellular structure. Hyaluronic acid (hyaluronan-HA) is a natural constituent of skin that generates formation and poliferation of new cells having a remarkable moisturizing ability. The aim of this study is to formulate HA microparticles loaded with caffeine via spray-drying method. Resulting microparticle formulations (33.97 ± 0.3 μm, span < 2, 88.56 ± 0.42% encapsulation efficiency) were distributed in lecithin organogels to maintain the proper viscosity for topical application. Following the characterization and cell culture studies, in vitro drug release and ex vivo permeation studies were performed. The accumulated amount of caffeine was twice higher than the aqueous solution for the microparticle-loaded organogels at 24 h (8262,673 μg/cm 2 versus 4676,691 μg/cm 2 ). It was related to the sustained behaviour of caffeine release from the microparticles. As a result, lecithin organogel containing HA-encapsulated microparticles could be considered as suitable candidate formulations for efficient topical drug delivery system of caffeine. In addition to that, synergistic effect of this combination appears as a promising approach for long-acting treatment of cellulite.

  11. Effect of cracks in coating on gas release from a fuel microparticle

    International Nuclear Information System (INIS)

    Bondarenko, A.G.; Gudkov, A.N.; Tselishchev, Yu.V.

    1988-01-01

    Effect of cracks in protective coating on gas release from a fuel microparticle is investigated in a general form. A fuel microparticle comprizing a kern, a buffer layer and an external protective coating is considered. The pressure of radioactive inert gases in the microparticle buffer layer is evaluated within the 1000-1800 K temperature range on the base of diffusion-defect-trap transport theory. It is shown that the process of radionuclide adsorption interaction with the coating material leads to a more abrupt than by exponent, weakening of mass transfer coefficient. In this case for long-living isotopes the effect of adsorption processes manifests weaker than for short-living ones. Mass transfer coefficient for the crack system depends sufficiently on the total pressure of gas mixture under the coating while for a single cracks such dependence is not observed. A conclusion is drawn that the obtained ratios can be applied for evaluating the character of fuel microparticle protective coating destruction (single non-intersecting cracks or a crack system) using the data on various nuclide release. These ratios can be also applied for the choice of the coating thichness under which gaseous fission product release from the fuel microparticle in case of its protective coating failure does not exceed the acceptable limits

  12. Effect of strenuous physical exercise on circulating cell-derived microparticles.

    Science.gov (United States)

    Chaar, Vicky; Romana, Marc; Tripette, Julien; Broquere, Cédric; Huisse, Marie-Geneviève; Hue, Olivier; Hardy-Dessources, Marie-Dominique; Connes, Philippe

    2011-01-01

    Strenuous exercise is associated with an inflammatory response involving the activation of several types of blood cells. In order to document the specific activation of these cell types, we studied the effect of three maximal exercise tests conducted to exhaustion on the quantitative and qualitative pattern of circulating cell-derived microparticles and inflammatory molecules in healthy subjects. This study mainly indicated that the plasma concentration of microparticles from platelets and polymorphonuclear neutrophils (PMN) was increased immediately after the strenuous exercise. In addition, the increase in plasma concentration of microparticles from PMN and platelets was still observed after 2 hours of recovery. A similar pattern was observed for the IL-6 plasma level. In contrast, no change was observed for either soluble selectins or plasma concentration of microparticles from red blood cells, monocytes and endothelial cells. In agreement, sVCAM-1 and sICAM-1 levels were not changed by the exercise. We conclude that a strenuous exercise is accompanied by platelet- and PMN-derived microparticle production that probably reflects the activation of these two cell types.

  13. Selective microrobot control using a thermally responsive microclamper for microparticle manipulation

    International Nuclear Information System (INIS)

    Go, Gwangjun; Choi, Hyunchul; Ko, Seong Young; Park, Jong-Oh; Park, Sukho; Jeong, Semi

    2016-01-01

    Microparticle manipulation using a microrobot in an enclosed environment, such as a lab-on-a-chip, has been actively studied because an electromagnetic actuated microrobot can have accurate motility and wireless controllability. In most studies on electromagnetic actuated microrobots, only a single microrobot has been used to manipulate cells or microparticles. However, the use of a single microrobot can pose several limitations when performing multiple roles in microparticle manipulation. To overcome the limitations associated with using a single microrobot, we propose a new method for the control of multiple microrobots. Multiple microrobots can be controlled independently by an electromagnetic actuation system and multiple microclampers combined with microheaters. To select a specific microrobot among multiple microrobots, we propose a microclamper composed of a clamper structure using thermally responsive hydrogel and a microheater for controlling the microclamper. A fundamental test of the proposed microparticle manipulation system is performed by selecting a specific microrobot among multiple microrobots. Through the independent locomotion of multiple microrobots with U- and V-shaped tips, heterogeneous microparticle manipulation is demonstrated in the creation of a two-dimensional structure. In the future, our proposed multiple-microrobot system can be applied to tasks that are difficult to perform using a single microrobot, such as cell manipulation, cargo delivery, tissue assembly, and cloning. (paper)

  14. Magnetic properties of novel dynamic self-assembled structures generated on the liquid/air interface

    International Nuclear Information System (INIS)

    Snezhko, A.; Aranson, I.S.

    2007-01-01

    We report on experimental and theoretical studies of magnetic properties of recently discovered dynamic multi-segment self-organized structures ('magnetic snakes'). Magnetic order and response of such snakes are determined by a novel unconventional mechanism provided by a self-induced surface wave. It gives rise to a nontrivial magnetic order: the segments of the snake exhibit long-range antiferromagnetic order mediated by the surface waves, while each segment is composed of ferromagnetically aligned chains of microparticles. Magnetic properties of the snakes are probed by in-plane magnetic field. A phenomenological model is proposed to explain the experimental observations

  15. One-Step Production of Protein-Loaded PLGA Microparticles via Spray Drying Using 3-Fluid Nozzle

    DEFF Research Database (Denmark)

    Wan, Feng; Maltesen, Morten Jonas; Andersen, Sune Klint

    2014-01-01

    The aim of this study was to investigate the potential of using a spray-dryer equipped with a 3-fluid nozzle to microencapsulate protein drugs into polymeric microparticles.......The aim of this study was to investigate the potential of using a spray-dryer equipped with a 3-fluid nozzle to microencapsulate protein drugs into polymeric microparticles....

  16. Effect of poly(lactide-co-glycolide) molecular weight on the release of dexamethasone sodium phosphate from microparticles.

    Science.gov (United States)

    Jaraswekin, Saowanee; Prakongpan, Sompol; Bodmeier, Roland

    2007-03-01

    The objective of this study was to investigate the effect of poly(lactide-co-glycolide) (PLGA) molecular weight (Resomer RG 502H, RG 503H, and RG 504H) on the release behavior of dexamethasone sodium phosphate-loaded microparticles. The microparticles were prepared by three modifications of the solvent evaporation method (O/W-cosolvent, O/W-dispersion, and W/O/W-methods). The encapsulation efficiency of microparticles prepared by the cosolvent- and W/O/W-methods increased from approximately 50% to >90% upon addition of NaCl to the external aqueous phase, while the dispersion method resulted in lower encapsulation efficiencies. The release of dexamethasone sodium phosphate from PLGA microparticles (>50 microm) was biphasic. The initial burst release correlated well with the porosity of the microparticles, both of which increased with increasing polymer molecular weight (RG 504H > 503H > 502H). The burst was also dependent on the method of preparation and was in the order of dispersion method > WOW method > consolvent method. In contrast to the higher molecular weight PLGA microparticles, the release from RG 502H microparticles prepared by cosolvent method was not affected by volume of organic solvent (1.5-3.0 ml) and drug loading (4-13%). An initial burst of approximately 10% followed by a 5-week sustained release phase was obtained. Microparticles with a size <50 microm released in a triphasic manner; an initial burst was followed by a slow release phase and then by a second burst.

  17. Neurokinin 1 Receptor Mediates Membrane Blebbing and Sheer Stress-Induced Microparticle Formation in HEK293 Cells

    Science.gov (United States)

    Chen, Panpan; Douglas, Steven D.; Meshki, John; Tuluc, Florin

    2012-01-01

    Cell-derived microparticles participate in intercellular communication similar to the classical messenger systems of small and macro-molecules that bind to specialized membrane receptors. Microparticles have been implicated in the regulation of a variety of complex physiopathologic processes, such as thrombosis, the control of innate and adaptive immunity, and cancer. The neurokinin 1 receptor (NK1R) is a Gq-coupled receptor present on the membrane of a variety of tissues, including neurons in the central and peripheral nervous system, immune cells, endocrine and exocrine glands, and smooth muscle. The endogenous agonist of NK1R is the undecapeptide substance P (SP). We have previously described intracellular signaling mechanisms that regulate NK1R-mediated rapid cell shape changes in HEK293 cells and U373MG cells. In the present study, we show that the activation of NK1R in HEK293 cells, but not in U373MG cells, leads to formation of sheer-stress induced microparticles that stain positive with the membrane-selective fluorescent dye FM 2–10. SP-induced microparticle formation is independent of elevated intracellular calcium concentrations and activation of NK1R present on HEK293-derived microparticles triggers detectable calcium increase in SP-induced microparticles. The ROCK inhibitor Y27632 and the dynamin inhibitor dynasore inhibited membrane blebbing and microparticle formation in HEK293 cells, strongly suggesting that microparticle formation in this cell type is dependent on membrane blebbing. PMID:23024816

  18. Neurokinin 1 receptor mediates membrane blebbing and sheer stress-induced microparticle formation in HEK293 cells.

    Directory of Open Access Journals (Sweden)

    Panpan Chen

    Full Text Available Cell-derived microparticles participate in intercellular communication similar to the classical messenger systems of small and macro-molecules that bind to specialized membrane receptors. Microparticles have been implicated in the regulation of a variety of complex physiopathologic processes, such as thrombosis, the control of innate and adaptive immunity, and cancer. The neurokinin 1 receptor (NK1R is a Gq-coupled receptor present on the membrane of a variety of tissues, including neurons in the central and peripheral nervous system, immune cells, endocrine and exocrine glands, and smooth muscle. The endogenous agonist of NK1R is the undecapeptide substance P (SP. We have previously described intracellular signaling mechanisms that regulate NK1R-mediated rapid cell shape changes in HEK293 cells and U373MG cells. In the present study, we show that the activation of NK1R in HEK293 cells, but not in U373MG cells, leads to formation of sheer-stress induced microparticles that stain positive with the membrane-selective fluorescent dye FM 2-10. SP-induced microparticle formation is independent of elevated intracellular calcium concentrations and activation of NK1R present on HEK293-derived microparticles triggers detectable calcium increase in SP-induced microparticles. The ROCK inhibitor Y27632 and the dynamin inhibitor dynasore inhibited membrane blebbing and microparticle formation in HEK293 cells, strongly suggesting that microparticle formation in this cell type is dependent on membrane blebbing.

  19. Quasi-static motion of microparticles at the depinning contact line of an evaporating droplet on PDMS surface

    Science.gov (United States)

    Yu, Ying-Song; Xia, Xue-Lian; Zheng, Xu; Huang, Xianfu; Zhou, Jin-Zhi

    2017-09-01

    In this paper, evaporation of sessile water droplets containing fluorescent polystyrene (PS) microparticles on polydimethylsiloxane (PDMS) surfaces with different curing ratios was studied experimentally using laser confocal microscopy. At the beginning, there were some microparticles located at the contact line and some microparticles moved towards the line. Due to contact angle hysteresis, at first both the contact line and the microparticles were pinned. With the depinning contact line, the microparticles moved together spontaneously. Using the software ImageJ, the location of contact lines at different time were acquired and the circle centers and radii of the contact lines were obtained via the least square method. Then the average distance of two neighbor contact lines at a certain time interval was obtained to characterize the motion of the contact line. Fitting the distance-time curve at the depinning contact line stage with polynomials and differentiating the polynomials with time, we obtained the velocity and acceleration of both the contact line and the microparticles located at the line. The velocity and the maximum acceleration were, respectively, of the orders of 1 μm/s and 20-200 nm/s2, indicating that the motion of the microparticles located at the depinning contact line was quasi-static. Finally, we presented a theoretical model to describe the quasi-static process, which may help in understanding both self-pinning and depinning of microparticles.

  20. The recognition and interpretation of micro-particle impacts on space craft surfaces

    Science.gov (United States)

    Kearsley, Anton

    Modern analysis instruments now allow the rapid examination of returned spacecraft surfaces, enabling the location and identification of impact features, and the attribution of their impactor origins. This paper describes application of novel electron, ion and micro-X-ray Fluorescence techniques to impacts on diverse compositions of substrate, including solar cell glass, poly-sulfone and fluoro-polymer-impregnated glass fibre composites, multilayer insulation foils, aluminium and titanium alloys. Examples will include two generations of solar cells and stiffener materials from the Hubble Space Telescope (HST), Beta-cloth from the NASA Mir-Trek cover blanket, aluminised Kapton foils from the Japanese Space Flyer Unit (SFU) and the European Retrievable Carrier (EuReCa), Al-alloy plates from the Long Duration Exposure Facility (LDEF), Al foils from the NASA Stardust mission, Al-alloy and Zinc orthotitanate (ZOT) painted alloy plate from HST, and titanium alloys from a re-entered titanium pressure tank. Each type of spacecraft surface poses unique problems of analysis, especially in the recognition of extraneous signatures from the impacting particle, especially if a complex chemical composition is already present in the target. For example, solar cells provide an excellent capture and analysis medium for monitoring fluxes of micrometre-scale orbital debris from solid rocket motor firings in low Earth orbit. However, they provide a hard and dense capture medium upon which substantial modification of the impactor may occur, making the precise identification of micrometeoroid components difficult. Unfortunately, extensive spallation by larger (> 100 micrometre) particle impacts on the thin and brittle structure of solar cells also usually results in complete loss of impactor signature. Although thick alloy surfaces may prevent complete impact penetration, the analysis of particle residues within their deep concavity has proven difficult, until the recent introduction of