WorldWideScience

Sample records for monodisperse polymer microspheres

  1. PREPARATION OF MONODISPERSE CROSSLINKED POLYMER MICROSPHERES HAVING CHLOROMETHYL GROUP BY DISTILLATION-PRECIPITATION POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Shu-Feng Li; Xin-Lin Yang; Wen-Qiang Huang

    2005-01-01

    Monodisperse crosslinked poly(chloromethylstyrene-co-divinylbenzene) (poly(CMSt-co-DVB)) microspheres were prepared by distillation-precipitation copolymerization of chloromethylstyrene (CMSt) and divinylbenzene (DVB) in neat acetonitrile. The polymer particles had clean surfaces due to the absence of any added stabilizer. The size of the particles ranges from 2.59 μm to 3.19 μm and with mono-dispersity around 1.002-1.014. The effects of monomer feed in copolymerization on the microsphere formation were described. The polymer microspheres were characterized by SEM and chlorinity elemental analysis.

  2. Preparation of monodisperse magnetic polymer microspheres by swelling and thermolysis technique.

    Science.gov (United States)

    Yang, Chengli; Shao, Qian; He, Jie; Jiang, Biwang

    2010-04-06

    A novel process for the preparation of monodisperse magnetic polymer microspheres by uniquely combining swelling and thermolysis technique was reported. The monodisperse polystyrene microspheres were first prepared by dispersion polymerization and swelled in chloroform. Then, ferric oleate was dispersed in chloroform as a precursor and impregnated into the swollen polymer microspheres. Subsequently, the iron oxide nanoparticles were formed within the polymer matrix by thermal decomposition of ferric oleate. The morphology, inner structure, and magnetic properties of the magnetic polymer microspheres were studied with a field emission scanning electron microscope (SEM), transmission electron microscope (TEM), and superconducting quantum interference device (SQUID) magnetometer. The results showed that the average diameter of the magnetic polymer microspheres was 5.1 microm with a standard deviation of 0.106, and the magnetic polymer microspheres with saturation magnetization of 12.6 emu/g exhibited distinct superparamagnetic characteristics at room temperature. More interestingly, the magnetite nanoparticles with a spinel structure are evenly distributed over the whole area of the polymer microspheres. These magnetic polymer microspheres have potential applications in biotechnology.

  3. Producing monodisperse drug-loaded polymer microspheres via cross-flow membrane emulsification: the effects of polymers and surfactants.

    Science.gov (United States)

    Meyer, Robert F; Rogers, W Benjamin; McClendon, Mark T; Crocker, John C

    2010-09-21

    Cross-flow membrane emulsification (XME) is a method for producing highly uniform droplets by forcing a fluid through a small orifice into a transverse flow of a second, immiscible fluid. We investigate the feasibility of using XME to produce monodisperse solid microspheres made of a hydrolyzable polymer and a hydrophobic drug, a model system for depot drug delivery applications. This entails the emulsification of a drug and polymer-loaded volatile solvent into water followed by evaporation of the solvent. We use a unique side-view visualization technique to observe the details of emulsion droplet production, providing direct information regarding droplet size, dripping frequency, wetting of the membrane surface by the two phases, neck thinning during droplet break off, and droplet deformation before and after break off. To probe the effects that dissolved polymers, surfactants, and dynamic interfacial tension may have on droplet production, we compare our results to a polymer and surfactant-free fluid system with closely matched physical properties. Comparing the two systems, we find little difference in the variation of particle size as a function of continuous phase flow rate. In contrast, at low dripping frequencies, dynamic interfacial tension causes the particle size to vary significantly with drip frequency, which is not seen in simple fluids. No effects due to shear thinning or fluid elasticity are detected. Overall, we find no significant impediments to the application of XME to forming highly uniform drug-loaded microspheres.

  4. Self-assembly of monodisperse polymer microspheres from PPQ-b-PEG rod-coil block copolymers in selective solvents

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xueao; CHEN Ke; XIE Kai; LONG Yongfu

    2005-01-01

    Poly(phenylquinoline)-block-poly(ethylene glycol)(PPQ-b-PEG) rod-coil block copolymers possess the self-assembly behavior in selective solvents. The copolymers in the mixed solvents of V(trifluoroacetic acid, TFA):V(dichloromethane, DCM)=1:1 can self-assemble into polymer hollow microspheres with diameters of a few micrometers. The polymer hollow microspheres are monodisperse, and the diameters of them increase with an increased polymerization degree of the PPQ rigid-rod block. The solution concentration has no effect on the microsphere diameter, but spherical surface shows burrs when the solution concentration is too low. It has been found that the obtained dilute solution has the strongest absorption peak at 376 nm and strongest emission peak at 604 nm by the spectroscopy analysis.

  5. Comparative DNA isolation behaviours of silica and polymer based sorbents in batch fashion: monodisperse silica microspheres with bimodal pore size distribution as a new sorbent for DNA isolation.

    Science.gov (United States)

    Günal, Gülçin; Kip, Çiğdem; Eda Öğüt, S; İlhan, Hasan; Kibar, Güneş; Tuncel, Ali

    2017-03-22

    Monodisperse silica microspheres with bimodal pore-size distribution were proposed as a high performance sorbent for DNA isolation in batch fashion under equilibrium conditions. The proposed sorbent including both macroporous and mesoporous compartments was synthesized 5.1 μm in-size, by a "staged shape templated hydrolysis and condensation method". Hydrophilic polymer based sorbents were also obtained in the form of monodisperse-macroporous microspheres ca 5.5 μm in size, with different functionalities, by a developed "multi-stage microsuspension copolymerization" technique. The batch DNA isolation performance of proposed material was comparatively investigated using polymer based sorbents with similar morphologies. Among all sorbents tried, the best DNA isolation performance was achieved with the monodisperse silica microspheres with bimodal pore size distribution. The collocation of interconnected mesoporous and macroporous compartments within the monodisperse silica microspheres provided a high surface area and reduced the intraparticular mass transfer resistance and made easier both the adsorption and desorption of DNA. Among the polymer based sorbents, higher DNA isolation yields were achieved with the monodisperse-macroporous polymer microspheres carrying trimethoxysilyl and quaternary ammonium functionalities. However, batch DNA isolation performances of polymer based sorbents were significantly lower with respect to the silica microspheres.

  6. Monodisperse raspberry-like multihollow polymer/Ag nanocomposite microspheres for rapid catalytic degradation of methylene blue.

    Science.gov (United States)

    Tian, Qiong; Yu, Xiaojing; Zhang, Lifeng; Yu, Demei

    2017-04-01

    Raspberry-like multihollow polymer microspheres were prepared by seeded swelling polymerization and decorated with silver nanoparticles (AgNPs) in the presence of polyvinylpyrrolidone (PVP) which acted as both reducing and stabilizing agent. Formation mechanism of the raspberry-like multihollow microsphere was discussed on the basis of water absorption of sulfonated groups in the seeded swelling polymerization. Effects of weight ratio of sodium 4-vinylbenzenesulfonate to styrene (NaSS/St) of the seed particles, the concentration of PVP and [Ag(NH3)2](+) ions on the properties of polymer/Ag nanocomposite microspheres were investigated by microscopic observation, nitrogen adsorption/desorption isotherms, UV-vis absorption spectra, X-ray diffraction patterns and thermogravimetric analysis. The results demonstrated that the raspberry-like multihollow microspheres were successfully fabricated by controlling over the NaSS/St of the seed particles in the seeded swelling polymerization by which the fabrication of hollow structure became simple and convenient. The spherical AgNPs were loaded on the polymer microsphere by in-situ chemical reduction due to the stabilization and reduction of PVP and the attraction between sulfonated groups and [Ag(NH3)2](+) ions. The raspberry-like multihollow polymer/Ag microspheres showed good catalytic activity and reusability in the degradation of methylene blue in the presence of NaBH4.

  7. Growth Kinetics of Monodisperse Polystyrene Microspheres Prepared by Dispersion Polymerization

    Directory of Open Access Journals (Sweden)

    Fan Li

    2013-01-01

    Full Text Available Dispersion polymerization has been widely applied to the synthesis of monodisperse micron-sized polymer colloidal spheres. Many efforts have been devoted to studying the influence of initial conditions on the size and uniformity of the resultant microspheres, aiming to synthesize micron-size monodisperse colloidal spheres. However, the inner contradiction between the size and the size distribution of colloidal spheres hinders the realization of this goal. In this work, we drew our attention from the initial conditions to the growth stage of dispersion polymerization. We tracked the size evolution of colloidal sphere during the dispersion polymerization, through which we established a kinetic model that described the relationship between the monomer concentration and the reaction time. The model may provide a guideline to prepare large polymer colloidal spheres with good monodispersity by continuous monomer feeding during the growth stage to maintain the concentration of monomer at a constant value in a dispersion polymerization process.

  8. Preparation of monodisperse, superparamagnetic, luminescent, and multifunctional PGMA microspheres with amino-groups

    Institute of Scientific and Technical Information of China (English)

    WANG WeiCai; ZHANG Qi; ZHANG BingBo; LI DeNa; DONG XiaoQing; ZHANG Lei; CHANG Jin

    2008-01-01

    Micron-sized, monodisperse, superparamagnetic, luminescent composite poly(glycidyl methacrylate) (PGMA) microspheres with functional amino-groups were successfully synthesized in this study. The process of preparation was as follows: preparation of monodisperse poly(glycidyl methacrylate) mi-crospheres by dispersion polymerization method; modification of poly(glycidyl methacrylate) micro-spheres with ethylene diamine to form amino-groups; impregnation of iron ions (Fe2+ and Fe3+) inside the microspheres and subsequently precipitating them with ammonium hydroxide to form magnetite (Fe3O,4>) nanoparticles within the polymer microspheres; infusion of CdSe/CdS core-shell quantum dots (QDs) into magnetic polymer microspheres. Scanning electron microscopy (SEM) was used to char-acterize surface morphology and size distribution of composite microspheres. The average size of mi-crospheres was 1.42μm with a size variation of 3.8%, The composite microspheres were bright enough and easily observed using a conventional fluorescence microscope, The composite microspheres were easily separated from solution by magnetic decantation using a permanent magnet. The new multi-functional composite microspheres are promising to be used in a variety of bioanalytical assays in-volving luminescence detection and magnetic separation.

  9. Preparation and characterization of monodisperse large-porous silica microspheres as the matrix for protein separation.

    Science.gov (United States)

    Xia, Hongjun; Wan, Guangping; Zhao, Junlong; Liu, Jiawei; Bai, Quan

    2016-11-04

    High performance liquid chromatography (HPLC) is a kind of efficient separation technology and has been used widely in many fields. Micro-sized porous silica microspheres as the most popular matrix have been used for fast separation and analysis in HPLC. In this paper, the monodisperse large-porous silica microspheres with controllable size and structure were successfully synthesized with polymer microspheres as the templates and characterized. First, the poly(glycidyl methacrylate-co-ethyleneglycol dimethacrylate) microspheres (PGMA-EDMA) were functionalized with tetraethylenepentamine (TEPA) to generate amino groups which act as a catalyst in hydrolysis of tetraethyl orthosilicate (TEOS) to form Si-containing low molecular weight species. Then the low molecular weight species diffused into the functionalized PGMA-EDMA microspheres by induction force of the amino groups to form polymer/silica hybrid microspheres. Finally, the organic polymer templates were removed by calcination, and the large-porous silica microspheres were obtained. The compositions, morphology, size distribution, specific surface area and pore size distribution of the porous silica microspheres were characterized by infrared analyzer, scanning-electron microscopy, dynamic laser scattering, the mercury intrusion method and thermal gravimetric analysis, respectively. The results show that the agglomeration of the hybrid microspheres can be overcome when the templates were functionalized with TEPA as amination reagent, and the yield of 95.7% of the monodisperse large-porous silica microspheres can be achieved with high concentration of polymer templates. The resulting large-porous silica microspheres were modified with octadecyltrichlorosilane (ODS) and the chromatographic evaluation was performed by separating the proteins and the digest of BSA. The baseline separation of seven kinds of protein standards was achieved, and the column delivered a better performance when separating BSA digests

  10. Facile Method for Preparation of Silica Coated Monodisperse Superparamagnetic Microspheres

    Directory of Open Access Journals (Sweden)

    Xuan-Hung Pham

    2016-01-01

    Full Text Available This paper presents a facile method for preparation of silica coated monodisperse superparamagnetic microsphere. Herein, monodisperse porous polystyrene-divinylbenzene microbeads were prepared by seeded emulsion polymerization and subsequently sulfonated with acetic acid/H2SO4. The as-prepared sulfonated macroporous beads were magnetized in presence of Fe2+/Fe3+ under alkaline condition and were subjected to silica coating by sol-gel process, providing water compatibility, easily modifiable surface form, and chemical stability. FE-SEM, TEM, FT-IR, and TGA were employed to characterize the silica coated monodisperse magnetic beads (~7.5 μm. The proposed monodisperse magnetic beads can be used as mobile solid phase particles candidate for protein and DNA separation.

  11. Synthesis of monodisperse crosslinked polystyrene microspheres

    Institute of Scientific and Technical Information of China (English)

    Jiang Kai; Chen Sheng-Li; Dong Peng; Liu Renxiao

    2008-01-01

    Monodisperse crosslinked polystyrene (CPS) particles were prepared through the normal emulsion polymerization method by adding crosslinker-divinylbenzene (DVB) into the reaction system after polystyrene (PS) particles grew to ~80% of the final size. When the amount of crosslinker DVB added was less than 6.17 wt% based on styrene, the prepared CPS particles were spherical and uniform and the size of the CPS particles could be predicted through the normal emulsion method. The glass transition temperature (Tg) of the prepared CPS particles was higher than that of un-crosslinked PS particles and, the more crosslinker that was added, the higher the Tg of CPS Particles. The prepared CPS particles had strong resistance to organic solvents.

  12. Synthesis and characterization of monodispersed inorganic/organic core/shell microspheres with fluorescence

    Institute of Scientific and Technical Information of China (English)

    ZHANG Kai; HAN Kun; ZHANG Xuehai; YANG Bai

    2005-01-01

    @@ In recent years, the semiconductor nanocrystals (NCs) have attracted great interest due to their potentials in photonics, electronics, magnetics and catalysis, and the monodispersed organic or inorganic microspheres doped NCs display predominant characteristics in the fabrication and study for photonic crystals[1,2], and considerable effort has been devoted to the design and synthesis of CdTe NCs doped colloid with well fluorescence[3-8]. For example, CdTe NCs were fabricated on the surfaces of silica or polymer microspheres by the methods of layer-by-layer assembly, and CdTe NCs were also doped into inorganic or organic microspheres through sol-gel process or swell- ing.

  13. Biotemplate synthesis of monodispersed iron phosphate hollow microspheres.

    Science.gov (United States)

    Cao, Feng; Li, Dongxu

    2010-03-01

    Monodispersed iron phosphate hollow microspheres with a high degree of crystallization were prepared through a facile in situ deposition method using rape pollen grains as a biotemplate. The functional group on the surface of the pollen grains could adsorb Fe(3+), which provided the nucleation sites for growth of iron phosphate nanoparticles. After being sintered at 600 degrees C for 10 h, the pollen grains were removed and iron phosphate hollow microspheres were obtained. A scanning electron microscope and x-ray diffraction were applied to characterize the morphology and crystalline structure of the pollen grains, iron phosphate-coated pollen grains and iron phosphate hollow microspheres. Differential scanning calorimetry and thermogravity analyses were performed to investigate the thermal behavior of the iron phosphate-coated pollen grains during the calcinations. Energy dispersive spectroscopy and Fourier transform infrared spectroscopy were utilized to investigate the interaction between the pollen grains and iron phosphate. The effect of the pollen wall on the surface morphology of these iron phosphate hollow microspheres was also proven in this work.

  14. Biotemplate synthesis of monodispersed iron phosphate hollow microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Cao Feng; Li Dongxu, E-mail: dongxuli@njut.edu.c [College of Materials Science and Engineering, Nanjing University of Technology, Jiangsu Nanjing 210009 (China)

    2010-03-15

    Monodispersed iron phosphate hollow microspheres with a high degree of crystallization were prepared through a facile in situ deposition method using rape pollen grains as a biotemplate. The functional group on the surface of the pollen grains could adsorb Fe{sup 3+}, which provided the nucleation sites for growth of iron phosphate nanoparticles. After being sintered at 600 deg. C for 10 h, the pollen grains were removed and iron phosphate hollow microspheres were obtained. A scanning electron microscope and x-ray diffraction were applied to characterize the morphology and crystalline structure of the pollen grains, iron phosphate-coated pollen grains and iron phosphate hollow microspheres. Differential scanning calorimetry and thermogravity analyses were performed to investigate the thermal behavior of the iron phosphate-coated pollen grains during the calcinations. Energy dispersive spectroscopy and Fourier transform infrared spectroscopy were utilized to investigate the interaction between the pollen grains and iron phosphate. The effect of the pollen wall on the surface morphology of these iron phosphate hollow microspheres was also proven in this work.

  15. Spontaneous Breakup of Extended Monodisperse Polymer Melts

    DEFF Research Database (Denmark)

    Rasmussen, Henrik K.; Yu, Kaijia

    2011-01-01

    We apply continuum mechanical based, numerical modeling to study the dynamics of extended monodisperse polymer melts during the relaxation. The computations are within the ideas of the microstructural ‘‘interchain pressure’’ theory. The computations show a delayed necking resulting in a rupture...

  16. Polymer microspheres with structured surfaces

    NARCIS (Netherlands)

    Wagdare, N.A.; Baggerman, J.; Marcelis, A.T.M.; Boom, R.M.; Rijn, van C.J.M.

    2011-01-01

    Microspheres from polymethyl methacrylate (PMMA) and Eudragit FS 30D (a commercial copolymer of poly(methyl acrylate-co-methyl methacrylate-co-methacrylic acid) 7:3:1) were prepared using microsieve emulsification. A mixture of these polymers in dichloromethane (DCM) was dispersed into water, leadin

  17. Studies on Monodispersed Microspheres of Zinc Sulfide Doped with Mn2+

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, zinc acetate, manganese acetate and thiacetamide are used as raw materials to successfully synthesize monodispersed ZnS:Mn2+ microspheres by using hydrothermal method and taking P123 surfactant as a template. The products were characterized by XRD, STEM,FT-IR and N2 adsorption-desorption. And the results show that the diameter of this microsphere is 1.0 μm or so, which is larger than that of ZnS microsphere without Mn2+ doping, and it has monodispersion, smooth surface and uniform size. The doping of Mn2+ does not obviously change the structure of monodispersed ZnS microsphere. The photoluminescence peak lies in a wide band ranging from 450 to 650 nm, and the microspheres emit orange light;with the increase of Mn2+concentration, fluorescence intensity of ZnS:Mn2+ microsphere changes, and when the mole ratio of Mn2+:Zn2+is 0.3:1, the fluorescence intensity is the strongest.

  18. Facile Synthesis of Mono-Dispersed Polystyrene (PS/Ag Composite Microspheres via Modified Chemical Reduction

    Directory of Open Access Journals (Sweden)

    Wen Zhu

    2013-12-01

    Full Text Available A modified method based on in situ chemical reduction was developed to prepare mono-dispersed polystyrene/silver (PS/Ag composite microspheres. In this approach; mono-dispersed PS microspheres were synthesized through dispersion polymerization using poly-vinylpyrrolidone (PVP as a dispersant at first. Then, poly-dopamine (PDA was fabricated to functionally modify the surfaces of PS microspheres. With the addition of [Ag(NH32]+ to the PS dispersion, [Ag(NH32]+ complex ions were absorbed and reduced to silver nanoparticles on the surfaces of PS-PDA microspheres to form PS/Ag composite microspheres. PVP acted both as a solvent of the metallic precursor and as a reducing agent. PDA also acted both as a chemical protocol to immobilize the silver nanoparticles at the PS surface and as a reducing agent. Therefore, no additional reducing agents were needed. The resulting composite microspheres were characterized by TEM, field emission scanning electron microscopy (FESEM, energy-dispersive X-ray spectroscopy (EDS, XRD, UV-Vis and surface-enhanced Raman spectroscopy (SERS. The results showed that Ag nanoparticles (NPs were homogeneously immobilized onto the PS microspheres’ surface in the presence of PDA and PVP. PS/Ag composite microspheres were well formed with a uniform and compact shell layer and were adjustable in terms of their optical property.

  19. On-demand one-step synthesis of monodisperse functional polymeric microspheres with droplet microfluidics.

    Science.gov (United States)

    Yu, Xu; Cheng, Gong; Zhou, Ming-Da; Zheng, Si-Yang

    2015-04-07

    A simple and robust method for one-step synthesis of monodisperse functional polymeric microspheres was established by generation of reversed microemulsion droplets in aqueous phase inside microfluidic chips and controlled evaporation of the organic solvent. Using this method, water-soluble nanomaterials can be easily encapsulated into biodegradable Poly(D,L-lactic-co-glycolic acid) (PLGA) to form functional microspheres. By controlling the flow rate of microemulsion phase, PLGA polymeric microspheres with narrow size distribution and diameters in the range of ∼50-100 μm were obtained. As a demonstration of the versatility of the approach, high-quality fluorescent CdTe:Zn(2+) quantum dots (QDs) of various emission spectra, superparamagnetic Fe3O4 nanoparticles, and water-soluble carbon nanotubes (CNTs) were used to synthesize fluorescent PLGA@QDs, magnetic PLGA@Fe3O4, and PLGA@CNTs polymeric microspheres, respectively. In order to show specific applications, the PLGA@Fe3O4 were modified with polydopamine (PDA), and then the silver nanoparticles grew on the surfaces of the PLGA@Fe3O4@PDA polymeric microspheres by reducting the Ag(+) to Ag(0). The as-prepared PLGA@Fe3O4@PDA-Ag microspheres showed a highly efficient catalytic reduction of the 4-nitrophenol, a highly toxic substance. The monodisperse uniform functional PLGA polymeric microspheres can potentially be critically important for multiple biomedical applications.

  20. Effect of Mixed Solvent on Fabrication, Morphology and Monodispersity of Microspheres with Hydrophobic Poly(butyl methacrylate) Shells

    Institute of Scientific and Technical Information of China (English)

    XIAO Xincai; LU Cheng

    2012-01-01

    Monodisperse microspheres (mean diameter 200-300 nm) with polystyrene cores and poly(acrylamide-co-buty1 methacrylate) shells were prepared by using a free radical polymerization method.Moreover,the effect of mixed solvent on the preparation,morphology and monodispersity was investigated.The experimental results showed that solubility parameter of butyl methacrylate and solvent affected mainly the molding of monodisperse core-shell microspheres.When the microspheres were fabricated in a sequential synthesis process,addition of hydrophilic and organic solvent including butyl methacrylate led to spherical degree of the particles becoming worse,and the mean diameter of the microspheres decreased and the monodispersity became better with increasing the crosslinker methylenebisacrylamide dosage.

  1. Preparation and characterization of monodispersed PS/Ag composite microspheres through modified electroless plating

    Energy Technology Data Exchange (ETDEWEB)

    Ma Yuehui [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Zhang Qinghua, E-mail: qhzhang@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China)

    2012-07-15

    A modified electroless silver-plating process has been devised for the preparation of monodispersed, polystyrene/silver (PS/Ag) composite microspheres with tunable shell thickness. Tailoring was achieved by altering the concentration of the silver precursor in the plating bath. PS/Ag composite microspheres were characterized by field-emission scanning electron microscopy, ultraviolet-visible absorption, X-ray diffraction and thermogravimetric analysis. The results showed that a dense, stable and uniform silver nanoshell was formed on the surface of PS microspheres in the presence of poly(vinylpyrrolidone) and glucose. The bulk conductivity of the PS/Ag composites increased from 1.16 S/m to 3.57 Multiplication-Sign 10{sup 4} S/m, corresponding to a shell thickness of 35-198 nm. The PS/Ag composite microspheres with diameters of ca. 3 {mu}m might have great potential to be used as fillers in anisotropic conductive films because of the uniform diameter, low density and good conductivity of the microspheres.

  2. Preparation of monodisperse aqueous microspheres containing high concentration of l-ascorbic acid by microchannel emulsification.

    Science.gov (United States)

    Khalid, Nauman; Kobayashi, Isao; Neves, Marcos A; Uemura, Kunihiko; Nakajima, Mitsutoshi; Nabetani, Hiroshi

    2015-01-01

    Monodisperse aqueous microspheres containing high concentrations of l-ascorbic acid with different concentrations of sodium alginate (Na-ALG) and magnesium sulfate (MgSO4) were prepared by using microchannel emulsification (MCE). The continuous phase was water-saturated decane containing a 5% (w/w) hydrophobic emulsifier. The flow rate of the continuous phase was maintained at 10 mL h(-1), whereas the pressure applied to the disperse phase was varied between 3 and 25 kPa. The disperse phase optimized for successfully generating aqueous microspheres included 2% (w/w) Na-ALG and 1% (w/w) MgSO4. At a higher MgSO4 concentration, the generated microspheres resulted in coalescence and subsequent bursting. At a lower MgSO4 concentration, unstable and polydisperse microspheres were obtained. The aqueous microspheres generated from the MCs under optimized conditions had a mean particle diameter (dav) of 14-16 µm and a coefficient of variation (CV) of less than 8% at the disperse phase pressures of 5-15 kPa.

  3. Mono-dispersed cross-linked polystyrene micro-spheres prepared by seed swelling polymerization method

    Institute of Scientific and Technical Information of China (English)

    Dongsha WANG; Yanjun LIU

    2008-01-01

    A two-step swelling procedure was adopted to synthesize mono-dispersed and highly cross-linked poly (St-divinylbenzene) particles with PSt micro-spheres (1.80 μmin diameter). The PSt micro-spheres were prepared by a dispersion polymerization method and used as seeds. The effects of monomer concentration, ratio of ethanol to water, swelling reagents, crosslinking reagents, swelling temper-ature and agitation speed on particle size were investigated in detail. The morphologies and size distributions of these micro-spheres were examined by SEM and particle size analysis (PSA). The Tg of the micro-spheres was measured by DSC. The results indicate that the particles (6.20 μm in diameter) exhibit excellent mono dispersed property and high crosslinking degree when the concentration of the swelling reagent was 25%, the concentration of the cross-linking reagents was 23%, the swelling temperature was 30℃ and the stirring speed was 150 r/min.

  4. Preparation and Characterization of Gd3+-doped Monodisperse TiO2 Hollow Microsphere

    Institute of Scientific and Technical Information of China (English)

    JI; Feng; SHANG; Pengbo; ZHENG; Yuying

    2015-01-01

    Gd3+-doped monodisperse TiO2 hollow microspheres with various molar ratios of Gd3+/TBOT were synthesized via a novel process, which involved the preparation of SiO2 templates, deposition of Gd3+-doped TiO2 by sol-gel, SiO2 coating, heat treatment to induce crystallization of TiO2, and finally etching away the inner SiO2 templates and outer SiO2 layers. The synthesized samples were characterized by transmission electron microscopy(TEM), scanning electron microscopy(SEM), X-ray diffraction(XRD), diffuse reflection spectroscopy(DRS), specific surface area measurement(BET) and X-ray photoelectron spectroscopy(XPS), respectively. The photocatalytic activity of Gd3+-doped samples was evaluated via photocatalytic degradation of Methyl orange under UV irradiation. The results show that the SiO2 layers prevent aggregation of TiO2 hollow microspheresand improve the thermal stability of the synthesized samples. Also, the photocatalytic activity of monodisperse TiO2 hollow microspheres can be enhanced at the optimal molar ration of Gd3+/TBOT of 0.7%.

  5. Templated synthesis of monodisperse mesoporous maghemite/silica microspheres for magnetic separation of genomic DNA

    Science.gov (United States)

    Chen, Feng; Shi, Ruobing; Xue, Yun; Chen, Lei; Wan, Qian-Hong

    2010-08-01

    A novel method is described for the preparation of superparamagnetic mesoporous maghemite (γ-Fe 2O 3)/silica (SiO 2) composite microspheres to allow rapid magnetic separation of DNA from biological samples. With magnetite (Fe 3O 4) and silica nanoparticles as starting materials, such microspheres were synthesized by the following two consecutive steps: (1) formation of monodispersed organic/inorganic hybrid microspheres through urea-formaldedyde (UF) polymerization and (2) removal of the organic template and phase transformation of Fe 3O 4 to γ-Fe 2O 3 by calcination at elevated temperatures. The as-synthesized particles obtained by heating at temperature 300 °C feature spherical shape and uniform particle size ( dparticle=1.72 μm), high saturation magnetization ( Ms=17.22 emu/g), superparamagnetism ( Mr/ Ms=0.023), high surface area ( SBET=240 m 2/g), and mesoporosity ( dpore=6.62 nm). The composite microsphere consists of interlocked amorphous SiO 2 nanoparticles, in which cubic γ-Fe 2O 3 nanocrystals are homogeneously dispersed and thermally stable against γ- to α-phase transformation at temperatures up to 600 °C. With the exposed iron oxide nanoparticles coated with a thin layer of silica shell, the magnetic microspheres were used as a solid-phase adsorbent for rapid extraction of genomic DNA from plant samples. The results show that the DNA templates isolated from pea and green pepper displayed single bands with molecular weights greater than 8 kb and A260/ A280 values of 1.60-1.72. The PCR amplification of a fragment encoding the endogenous chloroplast ndhB gene confirmed that the DNA templates obtained were inhibitor-free and amenable to sensitive amplification-based DNA technologies.

  6. Templated synthesis of monodisperse mesoporous maghemite/silica microspheres for magnetic separation of genomic DNA

    Energy Technology Data Exchange (ETDEWEB)

    Chen Feng; Shi Ruobing; Xue Yun; Chen Lei [School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072 (China); Wan Qianhong, E-mail: qhwan@tju.edu.c [School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072 (China)

    2010-08-15

    A novel method is described for the preparation of superparamagnetic mesoporous maghemite (gamma-Fe{sub 2}O{sub 3})/silica (SiO{sub 2}) composite microspheres to allow rapid magnetic separation of DNA from biological samples. With magnetite (Fe{sub 3}O{sub 4}) and silica nanoparticles as starting materials, such microspheres were synthesized by the following two consecutive steps: (1) formation of monodispersed organic/inorganic hybrid microspheres through urea-formaldedyde (UF) polymerization and (2) removal of the organic template and phase transformation of Fe{sub 3}O{sub 4} to gamma-Fe{sub 2}O{sub 3} by calcination at elevated temperatures. The as-synthesized particles obtained by heating at temperature 300 deg. C feature spherical shape and uniform particle size (d{sub particle}=1.72 mum), high saturation magnetization (M{sub s}=17.22 emu/g), superparamagnetism (M{sub r}/M{sub s}=0.023), high surface area (S{sub BET}=240 m{sup 2}/g), and mesoporosity (d{sub pore}=6.62 nm). The composite microsphere consists of interlocked amorphous SiO{sub 2} nanoparticles, in which cubic gamma-Fe{sub 2}O{sub 3} nanocrystals are homogeneously dispersed and thermally stable against gamma- to alpha-phase transformation at temperatures up to 600 deg. C. With the exposed iron oxide nanoparticles coated with a thin layer of silica shell, the magnetic microspheres were used as a solid-phase adsorbent for rapid extraction of genomic DNA from plant samples. The results show that the DNA templates isolated from pea and green pepper displayed single bands with molecular weights greater than 8 kb and A{sub 260}/A{sub 280} values of 1.60-1.72. The PCR amplification of a fragment encoding the endogenous chloroplast ndhB gene confirmed that the DNA templates obtained were inhibitor-free and amenable to sensitive amplification-based DNA technologies.

  7. Chemical template-assisted synthesis of monodisperse rattle-type Fe3O4@C hollow microspheres as drug carrier.

    Science.gov (United States)

    Cheng, Lin; Ruan, Weimin; Zou, Bingfang; Liu, Yuanyuan; Wang, Yongqiang

    2017-08-01

    A chemical template strategy was put forward to synthesize monodisperse rattle-type magnetic carbon (Fe3O4@C) hollow microspheres. During the synthesis procedure, monodisperse Fe2O3 microspheres were used as chemical template, which released Fe(3+) ions in acidic solution and initiated the in-situ polymerization of pyrrole into polypyrrole (PPy) shell. With the continual acidic etching of Fe2O3 microspheres, rattle-type Fe2O3@PPy microspheres were generated with the cavity appearing between the PPy shell and left Fe2O3 core, which were then transformed into Fe3O4@C hollow microspheres through calcination in nitrogen atmosphere. Compared with traditional physical template, the shell and cavity of rattle-type hollow microspheres were generated in one step using the chemical template method, which obviously saved the complex procedures including the coating and removal of middle shells. The experimental results exhibited that the rattle-type Fe3O4@C hollow microspheres with different parameters could be regulated through controlled synthesis of the intermediate Fe2O3@PPy product. Moreover, when the rattle-type Fe3O4@C hollow microspheres were investigated as drug carrier, they manifested sustained-release behaviour of doxorubicin, justifying their promising applications as carriers in drug delivery. The aim of the present study was first to synthesize rattle-type Fe3O4@C hollow microspheres through a simple synthesis method as a drug carrier. Here a chemical template synthesis of rattle-type hollow microspheres was developed, which saved the complex procedures including the coating and removal of middle shells in traditional physical template. Second, all the influence factors in the reaction processes were systematically investigated to obtain rattle-type Fe3O4@C hollow microspheres with controlled parameters. Third, the rattle-type Fe3O4@C hollow microspheres were studied as drug carriers and the influences of their structural parameters on drug loading and

  8. Poly(styrene-acrylic acid) magnetic polymer microspheres

    Institute of Scientific and Technical Information of China (English)

    Yanling CHENG; Liuqiang MA; Ruohui LI

    2008-01-01

    Magnetic polymer microspheres have been considered as a kind of new biopolymer materials with great advantages in bioseparation engineering and biome-dicine engineering because they have not only polymer functional groups but also magnetic characteristics. Styrene-acrylic acid copolymer (p(S-AA)) magnetic microspheres were synthesized by dispersion polymeriza-tion with Fe3O4 as core and p(S-AA) as shell. The micro-spheres were characterized by SEM, size analysis, molecular weight and solid content measurement. All of them indicate that the microspheres are small in size, nar-row in distribution, stable in chemistry and rich in func-tional groups on their surface.

  9. PREPARATION OF MONODISPERSE POLYSTYRENE MICROSPHERES BY SHELL POROUS GLASS-SUSPENSION POLYMERIZATION%用多孔玻璃膜管-悬浮聚合法制备单分散性聚苯乙烯微球

    Institute of Scientific and Technical Information of China (English)

    范星河; 谢晓峰

    2001-01-01

    Monodisperse polystyrene microspheres are prepared by shell porous glass(SPG)-suspension polymerization. The influences of SPG on size and size dispersity of the microspheres are investigated. The properties of the microspheres are studied by GPC, TEM and SEM. The results indicate that the polystyrene microspheres possess definite monodispersibity and their particle size is in the range of 5~12μm.

  10. Interfacial Fast Release Layer in Monodisperse Poly (lactic-co-glycolic acid) Microspheres Accelerates the Drug Release.

    Science.gov (United States)

    Wu, Jun; Zhao, Xiaoli; Yeung, Kelvin W K; To, Michael K T

    2016-01-01

    Understanding microstructural evolutions of drug delivery devices during drug release process is essential for revealing the drug release mechanisms and controlling the drug release profiles. In this study, monodisperse poly (lactic-co-glycolic acid) microspheres in different diameters were fabricated by microfluidics in order to find out the relationships between the microstructural evolutions and the drug release profiles. It was found that poly (lactic-co-glycolic acid) microspheres underwent significant size expansion which took place from the periphery to the center, resulting in the formation of interfacial fast release layers. At the same time, inner pores were created and the diffusion rate was increased so that the early stage drug release was accelerated. Due to the different expansion rates, small poly (lactic-co-glycolic acid) microspheres tendered to follow homogeneous drug release while large poly (lactic-co-glycolic acid) microspheres tendered to follow heterogeneous drug release. This study suggests that the size expansion and the occurrence of interfacial fast release layer were important mechanisms for early stage drug release of poly (lactic-co-glycolic acid) microspheres.

  11. Solvothermal synthesis of monodispersed CoZr{sub 4}(PO{sub 4}){sub 6} microspheres and their application as microwave absorber

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Tingting [College of Chemistry, Beijing Normal University, Beijing 100875 (China); Sun, Genban, E-mail: gbsun@bnu.edu.cn [College of Chemistry, Beijing Normal University, Beijing 100875 (China); Ma, Shulan; Yang, Xiaojing [College of Chemistry, Beijing Normal University, Beijing 100875 (China); Hu, Changwen [Key Laboratory of Cluster Science, Ministry of Education of China and Department of Chemistry, Beijing Institute of Technology, Beijing 100081 (China)

    2012-03-15

    Graphical abstract: Monodispersed CoZr{sub 4}(PO{sub 4}){sub 6} porous microspheres with shell structure were synthesized via a combined solvothermal method and calcination route. The radar-wave absorbability of the purple sample calcined at 900 Degree-Sign C was strongest at the frequency of about 8.5 GHz. Highlights: Black-Right-Pointing-Pointer In this study we synthesized monodispersed CoZr{sub 4}(PO{sub 4}){sub 6} porous microspheres as microwave absorber. Black-Right-Pointing-Pointer The relationship between microstructures and the electromagnetic properties was indicated. Black-Right-Pointing-Pointer The radar-wave absorbability of the sample was included. -- Abstract: Monodispersed CoZr{sub 4}(PO{sub 4}){sub 6} microspheres with a diameter of 40 {mu}m were achieved via a combining solvothermal and calcination route. The crystallinity of the calcined microspheres with shell structure was improved, while the monodisperse property and morphologies remained. The possible formation mechanism of the porous CoZr{sub 4}(PO{sub 4}){sub 6} microspheres with nanoshell was proposed. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectra (FT-IR) technologies, thermal analysis (TG and DSC), nitrogen adsorption-desorption isotherms and network analyzer. The sample calcined at 900 Degree-Sign C shows a strongest absorbability in the radar-wave absorbability test.

  12. Spherical and polygonal shape of Au nanoparticles coated functionalized polymer microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ting; Li, Yingzhi; Zhang, Junxian; Qi, Yalong; Zhao, Xin; Zhang, Qinghua, E-mail: qhzhang@dhu.edu.cn

    2015-08-01

    Highlights: • PS/PPy with well-defined core/shell structures was prepared in aqueous solution. • Au NPs were coated on PS/PPy by the fixation and continuous growth process. • Mercapto-groups played a role in the number and morphology of Au shell. • PS/PPy/Au had homogeneous and dense Au coatings with different shape. - Abstract: Uniform polystyrene (PS)/polypyrrole (PPy) composite microspheres with well-defined core/shell structures are synthesized by chemical oxidative polymerization. Gold nanoparticles (Au NPs) are successfully coated on the surface of PS/PPy microspheres by means of electrostatic interactions due to the functionalized PPy coatings supplying sufficient amino groups and the additive of mercapto acetic acid. Furthermore, the as-prepared PS/PPy/Au microspheres serving as seeds facilitate Au NPs further growth by in situ reduction in HAuCl{sub 4} solution to obtain PS/PPy/Au spheres with the core/shell/shell structure. Morphology observation demonstrates that the monodisperse PS/PPy/Au microspheres compose of uniform cores and the compact coatings containing distinct two layers. X-ray diffraction and X-ray photoelectron spectroscope confirm the existence of PPy and Au on the surface of the composite spheres. This facile approach to preparing metal-coated polymer spheres supplies the potential applications in biosensors, electronics and medical diagnosis.

  13. One-pot synthesis and visible light photocatalytic activity of monodispersed AgIn{sub 5}S{sub 8} microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiangqing [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China); Wang, Lei; Wei, Dailong [School of Chemistry and Molecular Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China); Kang, Shizhao [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China); Mu, Jin, E-mail: mujin@sit.edu.cn [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China)

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► Monodispersed AgIn{sub 5}S{sub 8} microspheres were prepared in a one-pot process. ► The process is environmental friendly. ► The AgIn{sub 5}S{sub 8} microspheres display high photocatalytic activity. -- Abstract: Monodispersed AgIn{sub 5}S{sub 8} microspheres were synthesized using a one-pot solution method and characterized with X-ray diffraction, UV–vis diffuse reflectance spectroscopy, scanning electron microscope, energy dispersive X-ray spectroscopy and N{sub 2} adsorption–desorption isotherm. The results indicated that the AgIn{sub 5}S{sub 8} microspheres were of cubic spinel structure and the mean diameter of about 0.5 μm. In addition, the visible light photocatalytic activity of AgIn{sub 5}S{sub 8} microspheres was also investigated at room temperature. The AgIn{sub 5}S{sub 8} microspheres showed very high photocatalytic activity for the degradation of methyl orange with a degradation efficiency of about 98% under visible light irradiation for 20 min.

  14. Contact electrification in aerosolized monodispersed silica microspheres quantified using laser based velocimetry

    DEFF Research Database (Denmark)

    Alois, Stefano; Merrison, Jonathan P.; Iversen, Jens Jacob

    2017-01-01

    The contact electrification of aerosolized micro particles has been studied using a novel technique involving laser velocimetry. This has allowed the simultaneous determination of size and electrical charge of individual silica microspheres (in the range 1 – 8 µm). Interestingly the particles...

  15. Micro-spherical cochleate composites: method development for monodispersed cochleate system.

    Science.gov (United States)

    Nagarsekar, Kalpa; Ashtikar, Mukul; Steiniger, Frank; Thamm, Jana; Schacher, Felix H; Fahr, Alfred

    2017-03-01

    Cochleates have been of increasing interest in pharmaceutical research due to their extraordinary stability. However the existing techniques used in the production of cochleates still need significant improvements to achieve sufficiently monodispersed formulations. In this study, we report a simple method for the production of spherical composite microparticles (3-5 μm in diameter) made up of nanocochleates from phosphatidylserine and calcium (as binding agent). Formulations obtained from the proposed method were evaluated using electron microscopy and small angle X-ray scattering and were compared with conventional cochleate preparation techniques. In this new method, an ethanolic lipid solution and aqueous solution of a binding agent is subjected to rapid and uniform mixing with a microfluidic device. The presence of high concentration of organic solvent promotes the formation of composite microparticles made of nanocochleates. This simple methodology eliminates elaborate preparation methods, while providing a monodisperse cochleate system with analogous quality.

  16. 单分散ZnO微球的合成及表征%Synthesis of monodispersed ZnO microspheres and characterizations

    Institute of Scientific and Technical Information of China (English)

    颜蔚; 安明; 王响; 董琪琪; 孙丽宁; 施利毅; 邓维

    2012-01-01

    采用简单的两步法合成了直径范围从50~200 nm的单分散的ZnO微球:在第一步反应中制备了ZnO纳米粒子的乙醇分散液;然后在第二步反应中加入适量的ZnO纳米粒子的乙醇分散液,从而合成出单分散的ZnO微球.通过改变第二步反应中所加入的ZnO纳米粒子的乙醇分散液的量,可以改变制备的单分散ZnO微球的直径.通过透射电子显微镜和X-射线衍射分析可以得知,ZnO微球是由ZnO纳米粒子聚集而成.不论ZnO微球的直径是多少,其多分散指数均小于1,并且当ZnO微球的直径为150 nm时,其多分散指数仅为0.16.%In this paper, monodispersed ZnO microspheres in sizes from 50 to 200 nm were synthesized with a developed two-step method. In the primary reaction, ethanol suspension of ZnO nanoparticles was prepared, and monodispersed ZnO microspheres were synthesized in the secondary reaction by adding the ZnO nanoparticles suspension into the reaction solution. Diameter of the ZnO microspheres could be controlled by varying the volume of QDs suspension added. The transmission microscopy images and X-ray diffraction patterns of the ZnO microspheres showed that no matter their diameters, the ZnO microspheres were formed by aggregation of well crystallized ZnO nanoparticles. The polydispersity indexes (PDI) of ZnO microspheres were detected. It is found that PDI values of the microspheres were all less than 1. 0, suggesting the monodispersi-ty of the ZnO microspheres. The PDI value was only 0. 16 when the diameter of the ZnO microspheres was 150 nm.

  17. Dynamic dilution exponent in monodisperse entangled polymer solutions

    DEFF Research Database (Denmark)

    Shahid, T.; Huang, Qian; Oosterlinck, F.

    2017-01-01

    We study and model the linear viscoelastic properties of several entangled semi-dilute and concentrated solutions of linear chains of different molar masses and at different concentrations dissolved in their oligomers. We discuss the dilution effect of the oligomers on the entangled long chains...... of the long chain extremities. Then we discuss the influence of the polymer concentration on the terminal relaxation time of the solutions and how this can be modelled by the enhanced contour length fluctuation process (CR-CLF). We point out that this larger dilution effect is not only a function...... of concentration but also depends on the molar mass of the chains. While the proposed approach successfully explains the viscoelastic properties of a large number of semi-dilute solutions of polymers in their own oligomers, important discrepancies are found for semi-dilute entangled polymers in small...

  18. Upconversion Nanoparticles and Monodispersed Magnetic Polystyrene Microsphere Based Fluorescence Immunoassay for the Detection of Sulfaquinoxaline in Animal-Derived Foods.

    Science.gov (United States)

    Hu, Gaoshuang; Sheng, Wei; Zhang, Yan; Wang, Junping; Wu, Xuening; Wang, Shuo

    2016-05-18

    A novel fluorescence immunoassay for detecting sulfaquinoxaline (SQX) in animal-derived foods was developed using NaYF4:Yb/Tm upconversion nanoparticles (UCNPs) conjugated with antibodies as fluorescence signal probes, and monodisperse magnetic polystyrene microspheres (MMPMs) modified with coating antigen as immune-sensing capture probes for trapping and separating the signal probes. Based on a competitive immunoassay format, the detection limit of the proposed method for detecting SQX was 0.1 μg L(-1) in buffer and 0.5 μg kg(-1) in food samples. The recoveries of SQX in spiked samples ranged from 69.80 to 133.00%, with coefficients of variation of 0.24-25.06%. The extraction procedure was fast, simple, and environmentally friendly, requiring no organic solvents. In particular, milk samples can be analyzed directly after simple dilution. This method has appealing properties, such as sensitive fluorescence response, a simple and fast extraction procedure, and environmental friendliness, and could be applied to detecting SQX in animal-derived foods.

  19. HIGH IMMOBILIZATION OF ANTIBACTERIAL MOIETIES ONTO MONODISPERSE MICROSPHERES BY DISPERSION POLYMERIZATION USING BICATIONIC VIOLOGEN SURFMER

    Institute of Scientific and Technical Information of China (English)

    Sheng-liu Wang; Xiao-fang Yang; Lian-ying Liu; Wan-tai Yang

    2012-01-01

    In order to achieve monodisperse particles with high content of antibacterial groups covalently bonded on surface,a bicationic viologen,N-hexyl-N'-(4-vinylbenzyl)-4,4'-bipyridinium bromide chloride (HVV) was devised as a surfmer in dispersion polymerization of styrene (St) using a mixture of methanol (or ethylene glycol) and water as media.Effects of content of HVV,its addition profile and composition of reaction media on particles size and incorporation of HVV moieties were mainly investigated.The attachment of silver and gold nanoparticles on particle surface under UV irradiation ascertained the surface-bonded HVV segments.SEM,TEM observations and XPS,zata potential measurements indicated that increase of initial HVV contents and addition of HVV (when polymerization had been performed for 3 h) led to grown particles and enhanced immobilization of HVV moieties.Using a mixture of ethylene glycol and water as reaction media,small particles (520-142 nm) with highly attached HVV moieties were prepared.Furthermore,antibacterial efficacy of the resultant particles against S.aureus was assayed,and particles with more HVV moieties anchored on surface demonstrated greater efficiency of antibacterial activity.

  20. Monodisperse REPO4 (RE = Yb, Gd, Y) hollow microspheres covered with nanothorns as affinity probes for selectively capturing and labeling phosphopeptides.

    Science.gov (United States)

    Cheng, Gong; Zhang, Ji-Lin; Liu, Yan-Lin; Sun, De-Hui; Ni, Jia-Zuan

    2012-02-13

    Rare-earth phosphate microspheres with unique structures were developed as affinity probes for the selective capture and tagging of phosphopeptides. Prickly REPO(4) (RE = Yb, Gd, Y) monodisperse microspheres, that have hollow structures, low densities, high specific surface areas, and large adsorptive capacities were prepared by an ion-exchange method. The elemental compositions and crystal structures of these affinity probes were confirmed by energy-dispersive spectroscopy (EDS), powder X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectroscopy. The morphologies of these compounds were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen-adsorption isotherms. The potential ability of these microspheres for selectively capturing and labeling target biological molecules was evaluated by using protein-digestion analysis and a real sample as well as by comparison with the widely used TiO(2) affinity microspheres. These results show that these porous rare-earth phosphate microspheres are highly promising probes for the rapid purification and recognition of phosphopeptides.

  1. Temperature influence in crystallinity of polymer microspheres; Influencia da temperatura na cristalinidade de microesferas polimericas

    Energy Technology Data Exchange (ETDEWEB)

    Rezende, Cristiane de P.; Novack, Katia M., E-mail: knovack@iceb.ufop.br [Universidade Federal de Ouro Preto - UFOP, ICEB, DEQUI, Ouro Preto, MG (Brazil)

    2011-07-01

    Drug delivery technology is evolving through the creation of new techniques of drug delivery effectively. The new methods used in drugs administration are based in microencapsulation process. Microsphere encapsulation modifies drug delivery bringing benefits and efficiency. In this work has been evaluated the influence of temperature in microspheres preparation. Microspheres were obtained by PMMA-co-PEG (COP) copolymer with indomethacin inserted in polymer matrix. Samples were characterized by SEM, DSC and XRD. SEM micrographs confirmed the formation of different sizes of microspheres and it was verified that higher temperatures make more crystalline microspheres. (author)

  2. A review of recent progress in preparation of hollow polymer microspheres

    Institute of Scientific and Technical Information of China (English)

    Wei Bin; Wang Shujun; Song Hongguang; Liu Hongyan; Li Jie; Liu Ning

    2009-01-01

    The preparation methods of hollow polymer microspheres both at home and abroad are summarized, and their preparation mechanisms and developmental states are presented. These methods include the liquid droplet method, dried-gel droplet method, self-assembly method, microencapsulation method, emulsion polymerization method and the template method. Hollow polystyrene microspheres are the most extensively studied in the research of hollow polymer microspheres. Through comparison of the advantages and disadvantages of different preparation methods, it is concluded that microencapsulation method is most suitable for preparing polystyrene hollow microspheres.

  3. FORMULATION AND EVALUATION OF MUCOADHESIVE MICROSPHERES OF PIOGLITAZONE HYDROCHLORIDE USING A NATURAL POLYMER

    Directory of Open Access Journals (Sweden)

    Mobeen Mohd.

    2015-04-01

    Full Text Available The objective of the present investigation was to design a controlled release dosage form for a thiazolidinedione oral hypoglycemic drug i.e., pioglitazone hydrochloride employing a natural polymer. The present study was also aimed to increase the biological half-life by developing it in the form of sustained release microspheres. The present study aimed at employing a natural polymer in formulating the mucoadhesive microspheres and estimate its effect over the controlled release of the drug from the formulation. The microspheres of pioglitazone hydrochloride were prepared by employing sodium alginate as a cell forming polymer and by using a natural bio-adhesive polymer viz. goru gum in the ratios of 1:1, 1:1.5 and 1:2, by orifice ion gelation method with varying concentrations of calcium chloride. Six batches of microspheres (MS1 – MS6 were prepared. The microspheres were evaluated for various micromeritic properties and it was observed that all the batches exhibited free-flowing properties. Scanning electron microscopy results showed that the microspheres were almost spherical in shape and discrete. The FTIR results showed that there were no interactions between the drug and the excipients. The in vitro release profile indicated that all the batches of microspheres showed controlled and prolonged drug release over an extended period, with acceptable release kinetics. The work demonstrated that among all the formulations of microspheres, the microspheres of the formulation MS4 are promising candidates for the sustained release of pioglitazone hydrochloride.

  4. Monodisperse magnetic hydroxyapatite/Fe{sub 3}O{sub 4} microspheres for removal of lead(II) from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Fuqiang [Faculty of Electrical Engineering and Computer Science, Ningbo University, Ningbo 315211 (China); Tan, Ruiqin, E-mail: tanruiqin@nbu.edu.cn [Faculty of Electrical Engineering and Computer Science, Ningbo University, Ningbo 315211 (China); Shen, Wenfeng; Zhang, Xianpeng; Xu, Wei; Song, Weijie [Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

    2015-07-15

    Highlights: • Monodisperse HAp/Fe{sub 3}O{sub 4} microspheres were explored for the removal of lead(II). • The sorption capacity toward Pb{sup 2+} reached 440 mg/g at pH 3.0. • Pb{sup 2+}-loaded HAp/Fe{sub 3}O{sub 4} microspheres can be easily collected by magnetic separation. • The removal mechanism of Pb{sup 2+} was different at pH 2.0–6.0. - Abstract: Monodisperse magnetic hydroxyapatite (HAp)/Fe{sub 3}O{sub 4} microspheres were successfully synthesized and explored for the removal of lead(II) from aqueous solution. The mechanism of Pb{sup 2+} uptake was characterized using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. The sorption capacity toward Pb{sup 2+} reached 440 mg/g at pH 3.0 and equilibrium was achieved within 1 h. The experimental data followed the Langmuir isotherm model (R{sup 2} = 0.9969) and the kinetic results accorded with the pseudo-second-order model (R{sup 2} = 0.9970). The sorption of Pb{sup 2+} on the surfaces of HAp/Fe{sub 3}O{sub 4} and the following ion exchange are the primary mechanism at pH 3.0–6.0. The dissolution–precipitation mechanism response to the removal of Pb{sup 2+} when pH varied from 3.0 to 2.0. The Pb{sup 2+}-loaded magnetic HAp/Fe{sub 3}O{sub 4} could be separated conveniently.

  5. 单分散介孔二氧化硅微球的制备%Synthesis of monodisperse mesoporous silica microsphere

    Institute of Scientific and Technical Information of China (English)

    钟立峰; 宁海金; 徐先进; 廖道发

    2012-01-01

    Modified Stober method was used to prepare monodisperse mesoporous silica microsphere by two-step reaction including hydrolysis and condensation of tetraethyl orthosilicate(TEOS)with ammonia as catalyst.Effects of the reaction parameters on the size and mono-disperse of the microsphere were discussed based on many characterization tests.Results showed: the microsphere size increased with the increment of ammonia and TEOS concentrations while decreased at higher temperature due to the evaporation of ammonia;effects of the reaction time on the particle distribution existed mainly in the initial stage,then got smooth gradually.The comparison of small angle X ray analysis suggested that peak intensity of silica microsphere increased and the overlapping peaks drifted rightward after calcination,indicating that the surfactant molecules were removed from the hole and the aperture shrank at the same time.In addition,the texture of the product was affected by reaction conditions to some extent.The mechanism study revealed the formation of silica microsphere was achieved through TEOS hydrolysis and polycondensation two steps successively.This is a simple,effective and repeatable method,which may be used for mass production,for the preparation of mono-dispersed mesoporous silica microspheres.%在Stober方法基础上制备了单分散二氧化硅微球,系统研究了反应条件对成球粒径以及单分散性的影响。通过多种测试手段,发现随着正硅酸乙酯和氨水浓度的提高,成球的粒径逐渐增大;而温度的提高会促使氨水挥发而使得成球的粒径降低;反应时间在反应初期对成球粒径的影响很大,然后逐渐趋于平缓。经对煅烧前后产物的小角X射线衍射对比分析,发现煅烧后产物的峰强度增加,并且重叠峰向右漂移,指示表面活性剂分子从孔中移除并发生了孔径收缩现象,同时发现不同反应条件对产物的织构性质有一定的影响。研究了相关的反应机

  6. Ti(IV) carrying polydopamine-coated, monodisperse-porous SiO2 microspheres with stable magnetic properties for highly selective enrichment of phosphopeptides.

    Science.gov (United States)

    Salimi, Kouroush; Usta, Duygu Deniz; Çelikbıçak, Ömür; Pinar, Asli; Salih, Bekir; Tuncel, Ali

    2017-05-01

    A marked decrease in the saturation magnetization by the formation of functional shells around the magnetic core is an important disadvantage of magnetic core-shell nanoparticles. Another drawback of Ti(IV)-functionalized immobilized metal affinity chromatography (IMAC) sorbents is the acidic character of the binding medium used for Ti(4+) attachment onto composite magnetic nanoparticles, which causes an additional decrease in the saturation magnetization owing to the chemical interaction between the acidic moiety and the magnetic core. An IMAC sorbent in the form of magnetic microspheres with superior and stable magnetic properties with respect to magnetic core-shell nanoparticles was designed for phosphopeptide enrichment. Magnetic, monodisperse-porous silica microspheres (MagSiO2) 6μm in size were synthesized by a new staged-shape template hydrolysis-condensation protocol. A porous-silica shell layer was generated around the microspheres to protect the magnetic core from the acidic medium during Ti(4+) attachment (MagSiO2@SiO2). The MagSiO2@SiO2 microspheres were coated with a polydopamine shell (MagSiO2@SiO2@PDA) and Ti(4+) was attached onto the composite microspheres (MagSiO2@SiO2@PDA@Ti(IV)). Formation of the PDA layer and Ti(4+) attachment did not cause any significant decrease in the saturation magnetization. The platform exhibited excellent performance for phosphopeptide enrichment from the digests of phosphorylated proteins. Selectivity was investigated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The detection limit for phosphopeptide enrichment by the MagSiO2@SiO2@PDA@Ti(IV) microspheres from the tryptic digests of β-casein was 50 fmol/mL. Usability of the proposed magnetic sorbent with complex biological samples was demonstrated by successful enrichment of four phosphopeptides from human serum. The proposed sorbent showed stable performance over five repeated uses. Copyright © 2017 Elsevier B.V. All rights

  7. A new and facile method for measurement of apparent density of monodisperse polymer beads.

    Science.gov (United States)

    Zhang, Qi; Srinivasan, Balasubramanian; Li, Yuanpeng; Jing, Ying; Xing, Chengguo; Chang, Jin; Wang, Jian-Ping

    2010-03-15

    The apparent density, an intrinsic physical property of polymer beads, plays an important role in the application of beads in micro-total analysis systems and separation. Here we have developed a new, facile and milligram-scale method to describe the motion of beads in aqueous solution and further detect the apparent density of beads. The motion of beads in solutions is determined by the viscosity of solutions and the density difference between beads and solutions. In this study, using various glycerol aqueous solutions with certain viscosities and densities, the motion time (i.e. floating or sedimentation time) of hybrid polymer beads was experimentally measured and theoretically deduced, and consequently, the apparent density of monodisperse beads can be quickly and easily calculated. The results indicated that the present method provided a more precise way to predict the movement of hybrid beads in aqueous solution compared with the approach for commercial use. This new method can be potentially employed in flow cytometry, suspension stability, and particle analysis systems.

  8. Invertase immobilization by adsorption on polymer microspheres studied by radioiodination technique

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz, Alvaro A.A. de [Universidade Federal de Itajuba, MG (Brazil). Inst. de Ciencias Exatas. Dept. de Fisica e Quimica]. E-mail: alencar@unifei.edu.br; Pontin, Luiz F. [Universidade Federal de Itajuba, MG (Brazil). Inst. de Ciencias Exatas. Dept. de Matematica e Computacao]. E-mail: pontin@unifei.edu.br; Higa, Olga Z.; Ribela, Maria Tereza C.P. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Lab. de Biologia Molecular]. E-mail: ozahiga@ipen.br; Tomotani, Ester J.; Vitolo, Michele [Sao Paulo Univ., SP (Brazil). Faculdade de Ciencias Farmaceuticas. Dept. de Tecnologia Bioquimico-Farmaceutica]. E-mail: michenzi@usp.br

    2005-07-01

    In this paper, we report the study of the diffusion behavior of invertase onto polystyrene-divinylbenzene (PS-DVB) microspheres. To detect the surface concentration of protein adsorbed on the microspheres, the chloramine-T method was used to label invertase and has been applied to the study of protein sorption properties on the microspheres. The sorption isotherms and the diffusion coefficient (D{sub f}) were computed from experimental results and the concentration of bound invertase was determined in terms of the Fick's law. The Hill equation was applied to the data and the binding capacity of the microspheres were estimated. The results of adsorption show that the radiolabelling invertase method are efficacious at the protein surface concentration detection and can be used to investigate the enzyme immobilization by sorption properties of polymer microspheres. (author)

  9. Preparation of CdTe nanocrystal-polymer composite microspheres in aqueous solution by dispersing method

    Institute of Scientific and Technical Information of China (English)

    LI Minjie; WANG Chunlei; HAN Kun; YANG Bai

    2005-01-01

    Highly fluorescent CdTe nanocrystals were synthesized in aqueous solution, and then processible CdTe nanocrystal-polymer composites were fabricated by coating the aqueous nanocrystals with copolymers of styrene and octadecyl-p-vinyl-benzyldimethylammonium chloride (SOV- DAC) directly. A dichloromethane solution of CdTe nano- crystal-polymer composites was dispersed in the aqueous solution of poly (vinyl alcohol) (PVA) generating highly fluorescent microspheres. Experimental parameters such as the concentration of nanocrystal-polymer composites, the concentration of PVA, and stirring speed which had important effect on the preparation of the microspheres were investigated in detail with fluorescent microscope characterization.

  10. MAGNETIC POLYMER MICROSPHERE STABILIZED GOLD NANOCOLLOIDS AS A FACILELY RECOVERABLE CATALYST

    Institute of Scientific and Technical Information of China (English)

    Han Zhang; Xin-lin Yang

    2011-01-01

    Magnetically responsive hierarchical magnetite/silica/poly(ethyleneglycol dimethacrylate-co-4-vinylpyridine) (Fe3O4/SiO2/P(EGDMA-co-VPy)) tri-layer microspheres were used as stabilizers for gold metallic nanocolloids as a facilely recoverable catalyst with the reduction of 4-nitrophenol to 4-aminophenol as a model reaction. The magnetic microsphere stabilized gold metallic nanocolloids were prepared by in situ reduction of gold chloride trihydrate with borohydride as reductant via the stabilization effect of the pyridyl groups to gold nanoparticles on the surface of the outer shell-layer of the inorganic/polymer fri-layer microspheres.

  11. Synthetic Polymers at Interfaces: Monodisperse Emulsions Multiple Emulsions and Liquid Marbles

    Science.gov (United States)

    Sun, Guanqing

    The adsorption of polymeric materials at interfaces is an energetically favorable process which is investigated in much diversified fields, such as emulsions, bubbles, foams, liquid marbles. Pickering emulsion, which is emulsion stabilized by solid particles has been investigated for over one century and preparation of Pickering emulsion with narrow size distribution is crucial for both the theoretical study of the stabilization mechanism and practical application, such as templated fabrication of colloidosomes. The precise control over the size and functionality of polymer latices allows the preparation of monodisperse Pickering emulsions with desired sizes through SPG membrane emulsification at rather rapid rate compared to microfludic production. Double or multiple emulsions have long been investigated but its rapid destabilization has always been a major obstacle in applying them into practical applications. The modern living polymerization techniques allow us to prepare polymers with designed structure of block copolymers which makes it possible to prepare ultra-stable multiple emulsions. The precise tuning of the ratio of hydrophobic part over the hydrophilic can unveil the stabilization mechanism. Liquid marble is a new type of materials of which liquid droplets are coated by dry particles. The coating of an outer layer of dry particles renders the liquid droplets non-sticky at solid surface which is useful in transportation of small amount of liquid without leakage at extreme low friction force. The property of liquid marbles relies largely on the stabilizers and the drying condition of polymeric latices is shown to have great influence on the property of liquid marbles. Firstly, an introduction to the interfacial and colloidal science with special attention to topics on emulsions, multiple emulsion and liquid marbles is given in Chapter 1. The unique features of an interface and a discussion on the definition of colloids are introduced prior to the

  12. Microspheres

    Science.gov (United States)

    1990-01-01

    Vital information on a person's physical condition can be obtained by identifying and counting the population of T-cells and B-cells, lymphocytes of the same shape and size that help the immune system protect the body from the invasion of disease. The late Dr. Alan Rembaum developed a method for identifying the cells. The method involved tagging the T-cells and B-cells with microspheres of different fluorescent color. Microspheres, which have fluorescent dye embedded in them, are chemically treated so that they can link with antibodies. With the help of a complex antibody/antigen reaction, the microspheres bind themselves to specific 'targets,' in this case the T-cells or B-cells. Each group of cells can then be analyzed by a photoelectronic instrument at different wavelengths emitted by the fluorescent dyes. Same concept was applied to the separation of cancer cells from normal cells. Microspheres were also used to conduct many other research projects. Under a patent license Magsphere, Inc. is producing a wide spectrum of microspheres on a large scale and selling them worldwide for various applications.

  13. Synthesis and characterization of magnetic polymer microspheres with a core-shell structure

    Institute of Scientific and Technical Information of China (English)

    Ming; Lu; Shu; Bai; Kun; Yang; Yan; Sun

    2007-01-01

    Non-porous magnetic polymer microspheres with a core-shell structure were prepared by a novel micro-suspension polymerization technique.A stable iron oxide ferrofluid was used to supply the magnetic core, and the polymeric shell was made of glycidyl methacrylate (GMA monomer)and ethylene dimethacrylate (cross-linker). In the preparation, polyvinyl alcohol was used as the stabilizer, and a lauryl alcohol mixture as the dispersant. The influence of various conditions such as aqueous phase volume, GMA and initiator amounts, reaction time and stirring speed on the character of the microspheres was investigated. The magnetic microspheres were then characterized briefly. The results indicate that the microspheres with active epoxy groups had a narrow size distribution range from 1 to 10 μm with a volume-weighted mean diameter of 4.5 μm.The saturation magnetization reached 19.9 emu/g with little coercivity and remanence.

  14. PREPARATION OF POLYMER MICROSPHERES WITH PYRIDYL GROUP AND THEIR STABILIZED GOLD METALLIC COLLOIDS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Narrow disperse poly(ethyleneglycol dimethacrylate-co-4-vinylpyridine) (poly(EGDMA-co-4-VPy)) microspheres were prepared by distillation-precipitation copolymerization of ethyleneglycol dimethacrylate (EGDMA) and 4-vinylpyridine (4-VPy) with 2,2'-azobisisobutyronitrile (AIBN) as initiator in neat acetonitrile. The polymer microspheres containing pyridyl group were then utilized as stabilizer for gold metallic colloids with the diameter around 7 nm, which were prepared by the in situ reduction of gold chloride trihydrate with sodium borohydride through the coordination of the pyridyl group on the gel layer and surface of the microsphere with the gold metallic nano-particles. The catalytic properties of the pyridyl-functionalized microsphere-stabilized gold metallic colloids and the behavior of the stabilized-catalyst for the recycling were investigated with reduction of 4-nitrophenol to 4-aminophenol as a model reaction.

  15. Perfluoroalkyl-Functionalized Hyperbranched Polyglycerol as Pore Forming Agents and Supramolecular Hosts in Polymer Microspheres

    Directory of Open Access Journals (Sweden)

    Olaf Wagner

    2015-08-01

    Full Text Available Perfluoroalkyl-functionalized, hyperbranched polyglycerols that produce stable microbubbles are integrated into a microfluidic emulsion to create porous microspheres. In a previously-presented work a dendrimer with a perfluorinated shell was used. By replacing this dendrimer core with a hyperbranched core and evaluating different core sizes and degrees of fluorinated shell functionalization, we optimized the process to a more convenient synthesis and higher porosities. The new hyperbranched polyglycerol porogens produced more pores and can be used to prepare microspheres with porosity up to 12% (v/v. The presented preparation forms pores with a perfluoroalkyl-functionalized surface that enables the resulting microspheres to act as supramolecular host systems. The microspheres can incorporate gases into the pores and actives in the polymer matrix, while the perfluoroalkylated pore surface can be used to immobilize perfluoro-tagged molecules onto the pores by fluorous-fluorous interaction.

  16. Rose-like monodisperse bismuth subcarbonate hierarchical hollow microspheres: One-pot template-free fabrication and excellent visible light photocatalytic activity and photochemical stability for NO removal in indoor air

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Fan [College of Environmental and Biological Engineering, Chongqing Technology and Business University, Chongqing, 400067 (China); Department of Civil and Structural Engineering, Research Center for Environmental Technology and Management, The Hong Kong Polytechnic University, Hong Kong (China); Department of Environmental Engineering, Zhejiang University, Hangzhou 310027 (China); Lee, S.C., E-mail: ceslee@polyu.edu.hk [Department of Civil and Structural Engineering, Research Center for Environmental Technology and Management, The Hong Kong Polytechnic University, Hong Kong (China); Wu, Zhongbiao [Department of Environmental Engineering, Zhejiang University, Hangzhou 310027 (China); Huang, Yu [Department of Civil and Structural Engineering, Research Center for Environmental Technology and Management, The Hong Kong Polytechnic University, Hong Kong (China); Fu, Min [College of Environmental and Biological Engineering, Chongqing Technology and Business University, Chongqing, 400067 (China); Ho, Wing-Kei [Nano and Advanced Materials Institute Limited, Hosted by The Hong Kong University of Science and Technology, Hong Kong (China); Zou, Shichun [School of Marine Sciences, Sun Yat-Sen University, Guangzhou, 510275 (China); Wang, Bo [Department of Civil and Structural Engineering, Research Center for Environmental Technology and Management, The Hong Kong Polytechnic University, Hong Kong (China)

    2011-11-15

    Graphical abstract: Rose-like monodisperse hierarchical nitrogen doped (BiO){sub 2}CO{sub 3} hollow microspheres fabricated by a one-pot template-free method exhibit excellent visible light photocatalytic activity and photochemical stability in the removal of NO in indoor air. The special hierarchical microstructure, the high charge separation efficiency and two-band-gap structure in all contribute to the outstanding photocatalytic performance. Highlights: {yields} Rose-like monodisperse hierarchical (BiO){sub 2}CO{sub 3} hollow microspheres are fabricated. {yields} The (BiO){sub 2}CO{sub 3} microspheres are self-assembled of single-crystalline nanosheets. {yields} Nitrogen is in situ doped into the lattice of hierarchical (BiO){sub 2}CO{sub 3} microspheres. {yields} The (BiO){sub 2}CO{sub 3} microspheres exhibit outstanding visible light activity for NO removal. {yields} The (BiO){sub 2}CO{sub 3} microspheres also exhibit high photochemical stability. - Abstract: Rose-like monodisperse hierarchical (BiO){sub 2}CO{sub 3} hollow microspheres are fabricated by a one-pot template-free method for the first time based on hydrothermal treatment of ammonia bismuth citrate and urea in water. The microstructure and band structure of the as-prepared (BiO){sub 2}CO{sub 3} superstructure are characterized in detail by X-ray diffraction, Raman spectroscopy, Fourier transform-infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, N{sub 2} adsorption-desorption isotherms, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The monodisperse hierarchical (BiO){sub 2}CO{sub 3} microspheres are constructed by the self-assembly of single-crystalline nanosheets. The aggregation of nanosheets result in the formation of three dimensional hierarchical framework containing mesopores and macropores, which is favorable for efficient transport of reaction molecules and harvesting of photo-energy. The result reveals the existence of

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

    Science.gov (United States)

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

    2001-07-10

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

  18. Preparation and Determination of Drug-Polymer Interaction and In-vitro Release of Mefenamic Acid Microspheres Made of CelluloseAcetate Phthalate and/or Ethylcellulose Polymers

    Science.gov (United States)

    Jelvehgari, Mitra; Hassanzadeh, Davoud; Kiafar, Farhad; Delf Loveym, Badir; Amiri, Sara

    2011-01-01

    The objective of this study was to formulate and evaluate the drug-polymer interaction of mefenamic acid (MA) using two polymers with different characteristics as ethylcellulose (EC) and/or cellulose acetate phthalate (CAP). Microspheres were prepared by the modified emulsion solvent evaporation (MESE). The effect of drug-polymer interaction was studied for each of microspheres. Important parameters in the evaluation of a microencapsulation technique are encapsulation efficiency, yield production, particle size, surface characteristics of microspheres, scanning electronic microscopy (SEM), powder X-ray diffraction analysis (XRD), and differential scanning calorimetry (DSC). The in-vitro release studies are performed in Tris buffer (pH 9) with Sodium lauryl sulfate (SLS). Microspheres containing CAP and EC showed 68-97% and 63-76% of entrapment efficiency, respectively. The thermogram X-ray and DSC showed stable character of MA in the microspheres and revealed an absence of drug polymer interaction. The prepared microspheres were spherical in shape and had a size range of 235-436 μm for CAP-microspheres and 358-442 μm for EC-microspheres. The results suggest that MA was successfully and efficiently encapsulated; the release rates of matrix microspheres are related to the type of polymer, only when polymers (EC and CAP combine with 1 : 1 ratio) were used to get prolonged drug release with reducing the polymers content in the microspheres. Data obtained from in-vitro release for microspheres and commercial capsule were fitted to various kinetic models and the high correlation was obtained in the peppas model. Mefenamic acid, Ethylcellulose, Cellulose acetate phthalate, Microparticles, Modified emulsion-solvent evaporation. PMID:24250377

  19. Molecularly imprinted polymer microspheres for optical measurement of ultra trace nonfluorescent cyhalothrin in honey.

    Science.gov (United States)

    Gao, Lin; Li, Xiuying; Zhang, Qi; Dai, Jiangdong; Wei, Xiao; Song, Zhilong; Yan, Yongsheng; Li, Chunxiang

    2014-08-01

    In this study, we first present a general protocol for making fluorescent molecularly imprinted polymer microspheres via precipitation polymerisation. We first prepared the fluorescent molecularly imprinted polymer microspheres upon copolymerisation of acrylamide with a small quantity of allyl fluorescein in the presence of cyhalothrin to form recognition sites without doping. The as-synthesised microspheres exhibited spherical shape, high fluorescence intensity and highly selective recognition. Under optical conditions, polymer microspheres were successfully applied to selectively and sensitively detect cyhalothrin, and a linear relationship could be obtained covering the lower concentration range of 0-1.0nM with a correlation coefficient of 0.9936 described by the Stern-Volmer equation. A lower limit of detection was found to be 0.004nM. The results of practical detection suggested that the developed method was satisfactory for determination of cyhalothrin in honey samples. This study therefore demonstrated the potential of molecularly imprinted polymers for detection of cyhalothrin in food.

  20. Preparation and Determination of Drug-Polymer Interaction and In-vitro Release of Didanosine Microspheres made of Cellulose Acetate Phthalate or Ethyl cellulose Polymers

    OpenAIRE

    Sethi R. K; Barik B. B.; Sahoo S. K.

    2013-01-01

    The objective of this study was to formulate and evaluate the drug-polymer interaction of Didanosine using two polymers with different characteristics as Ethyl cellulose or Cellulose acetate phthalate. Microspheres were prepared by the emulsion solvent evaporation. The effect of drug-polymer interaction was studied for each of microspheres. Important parameters in the evaluation of a microencapsulation technique are encapsulation efficiency, yield production, particle size, surface characteri...

  1. Preparation and Characterization of Monodisperse Polystyrene Microspheres%单分散性聚苯乙烯微球的制备与表征

    Institute of Scientific and Technical Information of China (English)

    万纪强; 石志琪

    2012-01-01

    Appropriate amount of sodium styrene sulfonate is introduced into the system of styrene emulsion polymerization in copolymerization by using emulsifier-free emulsion polymerization. The polymerization process is divided into two stages, in the first stage the ratio of sodium styrene sulfonate and styrene is the key factor which determines latex diameter and the monodispersity. When the reaction achieves high conversion rate, the second stage's monomer mixture is added into the reactant. The ratio of the sodium styrene sulfonate and styrene in this stage determines the particle's final surface charge density. Through the above two stages by emulsifier-free emulsion polymerization, latex particle of particle size of 100~400nm, good monodispersity, high surface charge density with the core-shell structure is successfully prepared. On this foundation, the influence of the ratio of styrene and sodium styrene sulfonate in the first stage on latex particle diameter and the influence of latex particle diameter on the microsphere's surface charge density are discussed.%利用无皂乳液聚合[1,2],在苯乙烯的乳液聚合体系中引入适量的苯乙烯磺酸钠参与共聚合.聚合过程中分两阶段料,第一阶段中苯乙烯磺酸钠与苯乙烯的比例是决定乳胶粒粒径及单分散性的关键因素.当反应达到较高的转化率时,加入第二阶段单体混合物,此阶段中的苯乙烯磺酸钠与苯乙烯的比例决定了最终胶粒表面电荷密度.利用上述两阶段无皂乳液聚合法制备了粒径在100~400nm,单分散性较好,表面电荷密度较高并且具有核壳结构的乳胶粒.在此基础上,讨论了的第一阶段中苯乙烯和苯乙烯磺酸钠的比例对乳胶粒粒径的影响以及乳胶粒粒径对微球表面电荷密度的影响.

  2. Synthesis of biodegradable polymer-mesoporous silica composite microspheres for DNA prime-protein boost vaccination.

    Science.gov (United States)

    Ho, Jenny; Huang, Yi; Danquah, Michael K; Wang, Huanting; Forde, Gareth M

    2010-03-18

    DNA vaccines or proteins are capable of inducing specific immunity; however, the translation to the clinic has generally been problematic, primarily due to the reduced magnitude of immune response and poor pharmacokinetics. Herein we demonstrate a composite microsphere formulation, composed of mesoporous silica spheres (MPS) and poly(D,L-lactide-co-glycolide) (PLGA), enables the controlled delivery of a prime-boost vaccine via the encapsulation of plasmid DNA (pDNA) and protein in different compartments. Method with modified dual-concentric-feeding needles attached to a 40 kHz ultrasonic atomizer was studied. These needles focus the flow of two different solutions, which passed through the ultrasonic atomizer. The process synthesis parameters, which are important to the scale-up of composite microspheres, were also studied. These parameters include polymer concentration, feed flowrate, and volumetric ratio of polymer and pDNA-PEI/MPS-BSA. This fabrication technique produced composite microspheres with mean D[4,3] ranging from 6 to 34 microm, depending upon the microsphere preparation. The resultant physical morphology of composite microspheres was largely influenced by the volumetric ratio of pDNA-PEI/MPS-BSA to polymer, and this was due to the precipitation of MPS at the surface of the microspheres. The encapsulation efficiencies were predominantly in the range of 93-98% for pDNA and 46-68% for MPS. In the in vitro studies, the pDNA and protein showed different release kinetics in a 40 day time frame. The dual-concentric-feeding in ultrasonic atomization was shown to have excellent reproducibility. It was concluded that this fabrication technique is an effective method to prepare formulations containing a heterologous prime-boost vaccine in a single delivery system.

  3. Hydrogel microspheres from biodegradable polymers as drug delivery systems

    Science.gov (United States)

    A series of hydrogel microspheres were prepared from pectin, a hydrophilic biopolymer, and zein, a hydrophobic biopolymer, at varying weight ratios. The hydrogel formulation was conducted in the presence of calcium or other divalent metal ions at room temperature under mild conditions. Studies of ...

  4. High-density cell systems incorporating polymer microspheres as microenvironmental regulators in engineered cartilage tissues.

    Science.gov (United States)

    Solorio, Loran D; Vieregge, Eran L; Dhami, Chirag D; Alsberg, Eben

    2013-06-01

    To address the significant clinical need for tissue-engineered therapies for the repair and regeneration of articular cartilage, many systems have recently been developed using bioactive polymer microspheres as regulators of the chondrogenic microenvironment within high-density cell cultures. In this review, we highlight various densely cellular systems utilizing polymer microspheres as three-dimensional (3D) structural elements within developing engineered cartilage tissue, carriers for cell expansion and delivery, vehicles for spatiotemporally controlled growth factor delivery, and directors of cell behavior via regulation of cell-biomaterial interactions. The diverse systems described herein represent a shift from the more traditional tissue engineering approach of combining cells and growth factors within a biomaterial scaffold, to the design of modular systems that rely on the assembly of cells and bioactive polymer microspheres as building blocks to guide the creation of articular cartilage. Cell-based assembly of 3D microsphere-incorporated structures represents a promising avenue for the future of tissue engineering.

  5. Thermal evolution of structure and photocatalytic activity in polymer microsphere templated TiO2 microbowls

    Science.gov (United States)

    Erdogan, Deniz Altunoz; Polat, Meryem; Garifullin, Ruslan; Guler, Mustafa O.; Ozensoy, Emrah

    2014-07-01

    Polystyrene cross-linked divinyl benzene (PS-co-DVB) microspheres were used as an organic template in order to synthesize photocatalytic TiO2 microspheres and microbowls. Photocatalytic activity of the microbowl surfaces were demonstrated both in the gas phase via photocatalytic NO(g) oxidation by O2(g) as well as in the liquid phase via Rhodamine B degradation. Thermal degradation mechanism of the polymer template and its direct influence on the TiO2 crystal structure, surface morphology, composition, specific surface area and the gas/liquid phase photocatalytic activity data were discussed in detail. With increasing calcination temperatures, spherical polymer template first undergoes a glass transition, covering the TiO2 film, followed by the complete decomposition of the organic template to yield TiO2 exposed microbowl structures. TiO2 microbowl systems calcined at 600 °C yielded the highest per-site basis photocatalytic activity. Crystallographic and electronic properties of the TiO2 microsphere surfaces as well as their surface area play a crucial role in their ultimate photocatalytic activity. It was demonstrated that the polymer microsphere templated TiO2 photocatalysts presented in the current work offer a promising and a versatile synthetic platform for photocatalytic DeNOx applications for air purification technologies.

  6. Forces between insulin microspheres and polymers surfaces for a dry powder inhaler.

    Science.gov (United States)

    Strathmann, Steve C; Murphy, Mary Ann; Goeckner, Bruce A; Carter, Phillip W; Green, John-Bruce D

    2009-05-08

    Here we demonstrate the use of a colloidal probe atomic force microscope (AFM) to compare the interactions between a model protein microsphere (insulin) and a set of common device polymers (polytetrafluoroethylene, polyethylene and polypropylene) with and without antistatic additive. For inhalation-based delivery devices the solid protein microspheres will interact with the device surfaces under ambient atmospheric conditions, and as such we studied the particle device interaction at a range of relative humidities. The results clearly discriminate between the five different polymer choices, and the impact of the antistatic additive. Although the mechanistic understanding is incomplete, it is evident that the polypropylene with antistatic additive gives consistent and relatively small interaction forces over the entire humidity range. The other polymer surfaces have humidity ranges where the pull-off forces are substantially greater. At 80% relative humidity, the insulin-polymer adhesion forces were similar for all the polymers probably due to the dominance of static charge mitigation and surface hydration effects. Overall, direct measurement of adhesion forces between pharmaceutical microspheres and container substrates can help direct rational choice of plastics/coatings for medical devices.

  7. Preparation of P(DVB-co-MPS) inorganic-organic hybrid polymer microspheres

    Science.gov (United States)

    Wu, Chunrong; Zhang, Jimei; Dai, Zhao; Chen, Xiaoyu

    2010-07-01

    A novel inorganic-organic hybrid polymer microspheres were facilely synthesised by distillation-precipitation polymerization in absence of any stabilizer or surfcant. The process were conducted with [3-(Methacryloyloxy) propyl] trimethoxysilan (MPS) as monomer, divinyl benzene (DVB) as cross linking agent and azobisisobutyronitrile (AIBN) as initator in acetonitrile. A series of silica nanoparticles were prepared in accordance with the volume ratio of MPS, which was varied in the range of 10% to 50%. However, there is no microspheres obtained while the ratio up to 50%. Products were charactered by transmission electron micrograph (TEM) and fourier transform infrared spectroscopy (FTIR). We may infer it from the constructional formular and FTIR graph that there were silicon hydroxyl remained in the microsphere surface.

  8. Synthesis and Characterization of Molecular Imprinting Polymer Microspheres of Piperine: Extraction of Piperine from Spiked Urine

    Science.gov (United States)

    Roland, Rachel Marcella

    2016-01-01

    Molecularly imprinted polymer (MIP) microspheres for Piperine were synthesized by precipitation polymerization with a noncovalent approach. In this research Piperine was used as a template, acrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, and 2,2′-azobisisobutyronitrile (AIBN) as an initiator and acetonitrile as a solvent. The imprinted and nonimprinted polymer particles were characterized by using Fourier transform infrared spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM). The synthesized polymer particles were further evaluated for their rebinding efficiency by batch binding assay. The highly selected imprinted polymer for Piperine was MIP 3 with a composition (molar ratio) of 0.5 : 3 : 8, template : monomer : cross-linker, respectively. The MIP 3 exhibits highest binding capacity (84.94%) as compared to other imprinted and nonimprinted polymers. The extraction efficiency of highly selected imprinted polymer of Piperine from spiked urine was above 80%. PMID:28018704

  9. Lanthanide-containing polymer microspheres by multiple-stage dispersion polymerization for highly multiplexed bioassays.

    Science.gov (United States)

    Abdelrahman, Ahmed I; Dai, Sheng; Thickett, Stuart C; Ornatsky, Olga; Bandura, Dmitry; Baranov, Vladimir; Winnik, Mitchell A

    2009-10-28

    We describe the synthesis and characterization of metal-encoded polystyrene microspheres by multiple-stage dispersion polymerization with diameters on the order of 2 mum and a very narrow size distribution. Different lanthanides were loaded into these microspheres through the addition of a mixture of lanthanide salts (LnCl(3)) and excess acrylic acid (AA) or acetoacetylethyl methacrylate (AAEM) dissolved in ethanol to the reaction after about 10% conversion of styrene, that is, well after the particle nucleation stage was complete. Individual microspheres contain ca. 10(6)-10(8) chelated lanthanide ions, of either a single element or a mixture of elements. These microspheres were characterized one-by-one utilizing a novel mass cytometer with an inductively coupled plasma (ICP) ionization source and time-of-flight (TOF) mass spectrometry detection. Microspheres containing a range of different metals at different levels of concentration were synthesized to meet the requirements of binary encoding and enumeration encoding protocols. With four different metals at five levels of concentration, we could achieve a variability of 624, and the strategy we report should allow one to obtain much larger variability. To demonstrate the usefulness of element-encoded beads for highly multiplexed immunoassays, we carried out a proof-of-principle model bioassay involving conjugation of mouse IgG to the surface of La and Tm containing particles and its detection by an antimouse IgG bearing a metal-chelating polymer with Pr.

  10. Novel smart yolk/shell polymer microspheres as a multiply responsive cargo delivery system.

    Science.gov (United States)

    Du, Pengcheng; Liu, Peng

    2014-03-25

    An effective strategy was developed to fabricate the novel dually thermo- and pH-responsive yolk/shell polymer microspheres as a drug delivery system (DDS) for the controlled release of anticancer drugs via two-stage distillation precipitation polymerization and seed precipitation polymerization. Their pH-induced thermally responsive polymer shells act as a smart "valve" to adjust the diffusion of the loaded drugs in/out of the polymer containers according to the body environments, while the movable P(MAA-co-EGDMA) cores enhance the drug loading capacity for the anticancer drug doxorubicin hydrochloride (DOX). The yolk/shell polymer microspheres show a low leakage at high pH values but significantly enhanced release at lower pH values equivalent to the tumor body fluid environments at human body temperature, exhibiting the apparent tumor-environment-responsive controlled "on-off" drug release characteristics. Meanwhile, the yolk/shell microspheres expressed very low in vitro cytotoxicity on HepG2 cells. Consequently, their precise tumor-environment-responsive drug delivery performance and high drug loading capacity offer promise for tumor therapy.

  11. Computer Modeling Assisted Design of Monodisperse PLGA Microspheres with Controlled Porosity Affords Zero Order Release of an Encapsulated Macromolecule for 3 Months

    NARCIS (Netherlands)

    Kazazi-Hyseni, Filis; Landin, Mariana; Lathuile, Audrey; Veldhuis, Gert J.; Rahimian, Sima; Hennink, Wim E.; Kok, Robbert Jan; van Nostrum, Cornelus F.

    2014-01-01

    Purpose The aim of this study was the development of poly(D,L-lactide-co-glycolide) (PLGA) microspheres with controlled porosity, to obtain microspheres that afford continuous release of a macromolecular model compound (blue dextran). Methods PLGA microspheres with a size of around 40 μm and narrow

  12. Utilizing microsphere-based enhanced-intensity laser ablation for nanopatterning polymers

    Science.gov (United States)

    Peer, Akshit; Biswas, Rana

    2017-02-01

    We use rigorous scattering matrix simulations to develop a pathway for synthesizing nanopatterns on polymer surfaces. We consider a system in which the polymer surfaces are initially coated with periodic microspheres in a close packed lattice. When such a lattice is irradiated with a laser of desired wavelength and power, the electric field intensity beneath the spheres is enhanced by more than an order of magnitude, generating localized heating that can remove nanometersize volume of the material in a periodic array of nanocavities. The array of glass spheres can be self-assembled on any curved surface, and these spheres can be utilized as an optical lens to focus light energy within the surface. Our simulations show that the depth and size of the nano-cavities depends critically on the size of microspheres.

  13. Rose-like monodisperse bismuth subcarbonate hierarchical hollow microspheres: one-pot template-free fabrication and excellent visible light photocatalytic activity and photochemical stability for NO removal in indoor air.

    Science.gov (United States)

    Dong, Fan; Lee, S C; Wu, Zhongbiao; Huang, Yu; Fu, Min; Ho, Wing-Kei; Zou, Shichun; Wang, Bo

    2011-11-15

    Rose-like monodisperse hierarchical (BiO)(2)CO(3) hollow microspheres are fabricated by a one-pot template-free method for the first time based on hydrothermal treatment of ammonia bismuth citrate and urea in water. The microstructure and band structure of the as-prepared (BiO)(2)CO(3) superstructure are characterized in detail by X-ray diffraction, Raman spectroscopy, Fourier transform-infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, N(2) adsorption-desorption isotherms, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The monodisperse hierarchical (BiO)(2)CO(3) microspheres are constructed by the self-assembly of single-crystalline nanosheets. The aggregation of nanosheets result in the formation of three dimensional hierarchical framework containing mesopores and macropores, which is favorable for efficient transport of reaction molecules and harvesting of photo-energy. The result reveals the existence of special two-band-gap structure (3.25 and 2.0 eV) for (BiO)(2)CO(3). The band gap of 3.25 eV is intrinsic and the formation of smaller band gap of 2.0 eV can be ascribed to the in situ doped nitrogen in lattice. The performance of hierarchical (BiO)(2)CO(3) microspheres as efficient photocatalyst are further demonstrated in the removal of NO in indoor air under both visible light and UV irradiation. It is found that the hierarchical (BiO)(2)CO(3) microspheres not only exhibit excellent photocatalytic activity but also high photochemical stability during long term photocatalytic reaction. The special microstructure, the high charge separation efficiency due to the inductive effect, and two-band-gap structure in all contribute to the outstanding photocatalytic activities. The discovery of monodisperse hierarchical nitrogen doped (BiO)(2)CO(3) hollow structure is significant because of its potential applications in environmental pollution control, solar energy conversion, catalysis and other related

  14. Immunocapture of CD133-positive cells from human cancer cell lines by using monodisperse magnetic poly(glycidyl methacrylate) microspheres containing amino groups

    Energy Technology Data Exchange (ETDEWEB)

    Kuan, Wei-Chih [Department of Chemical Engineering, Systems Biology and Tissue Engineering Research Center, National Chung Cheng University, Minhisung 621, Taiwan (China); Horák, Daniel, E-mail: horak@imc.cas.cz [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6 (Czech Republic); Plichta, Zdeněk [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6 (Czech Republic); Lee, Wen-Chien [Department of Chemical Engineering, Systems Biology and Tissue Engineering Research Center, National Chung Cheng University, Minhisung 621, Taiwan (China)

    2014-01-01

    Magnetic poly(glycidyl methacrylate)-based macroporous microspheres with an average particle size of 4.2 μm were prepared using a modified multi-step swelling polymerization method and by introducing amino functionality on their surfaces. Antibody molecules were oxidized on their carbohydrate moieties and bound to the amino-containing magnetic microspheres via a site-directed procedure. CD133-positive cells could be effectively captured from human cancer cell lines (HepG2, HCT116, MCF7, and IMR-32) by using magnetic microspheres conjugated to an anti-human CD133 antibody. After further culture, the immunocaptured CD133-expressing cells from IMR-32 proliferated and gradually detached from the magnetic microspheres. Flow-cytometric analysis confirmed the enrichment of CD133-expressing cells by using the antibody-bound magnetic microspheres. Such microspheres suitable for immunocapture are very promising for cancer diagnosis because the CD133-expressing cells in cancer cell lines have been suggested to be cancer stem cells. - Highlights: • Multi-step swelling polymerization produced poly(glycidyl methacrylate) microspheres. • Anti-human CD133 antibodies were bound to the amino-containing magnetic microspheres. • CD133-positive cells were effectively captured from human cancer cell lines. • Immunocaptured CD133-expressing cells proliferated and were detached from microspheres. • Enrichment of CD133-expressing cells was confirmed by flow-cytometric analysis.

  15. Preparation of highly monodisperse fluorescent polymer particles by miniemulsion polymerization of styrene with a polymerizable surfactant.

    Science.gov (United States)

    Taniguchi, Tatsuo; Takeuchi, Naoki; Kobaru, Shotaro; Nakahira, Takayuki

    2008-11-01

    Miniemulsion polymerization of styrene (St) in the presence of a hydrophobe (hexadecane:HD) using a cationic polymerizable surfactant (N,N-dimethyl-N-n-dodecyl-N-2-methacryloyloxyethylammonium bromide:C(12)Br) and a cationic initiator (2,2'-azobis(2-amidinopropane) dihydrochloride:V50), called St/C(12)Br/V50 hereafter, proceeded efficiently compared with that using sodium dodecyl sulfate (SDS) and potassium persulfate (KPS), i.e., St/SDS/KPS, providing monodisperse polystyrene latex particles with a narrower particle size distribution. In St/C(12)Br/AIBN, where an oil-soluble initiator, i.e., 2,2'-azobisisobutyronitrile (AIBN), was used in place of V50, little changes in polymerization kinetics or in particle size distribution were observed, while a significant drop in polymerization rate and a broad particle size distribution were observed with St/SDS/AIBN. A polymerizable pyrene derivative (1-pyrenylmethyl methacrylate: PyMMA) was quantitatively incorporated into monodisperse latex particles in St/PyMMA/C(12)Br/V50 compared to pyrene (Py) in St/Py/C(12)Br/V50. Contrary to our expectation, however, increased excimer emission was observed with St/PyMMA/C(12)Br/V50 particles, indicating less evenly distributed pyrene chromophores in the particles. The fluorescence lifetime of pyrene chromophores in St/Py/C(12)Br/V50 particles was determined to be 286 ns, which was 17 times longer than that of pyrene in THF solution.

  16. 膜乳化法制备尺寸均-P(NIPAM-co-AAc)微球及其羧基分布%Distribution of Carboxyl Groups in Monodispersed Poly(N-Isopropylacylamide-co-Acrylic Acid) Microspheres Prepared by Membrane Emulsification

    Institute of Scientific and Technical Information of China (English)

    司天保; 秦佳; 王玉霞; 马光辉

    2011-01-01

    Temperature-/pH-responsive monodispersed poly(N-isopropyl acrylamide-co-acrylic acid) [P(NIPAM-co-AAc)] microspheres were prepared by Shirasu porous glass membrane emulsification at room temperature with N,N,N',N'-tetramethylethylenediamine as accelerator and cyclohexane/trichluromethane mixture as oil phase. The monodispersed P(NIPAM-co-AAc) microspheres with controllable diameter could be reproducibly obtained with cyclohexane-trichloromethane mixture (volumetric ratio 7:3) as oil phase and two stage stirring speeds (140 and and 170 r/min) under the membrane emulsification pressure of 2 kPa. Conductometric titration was used to determine the distribution of carboxyl groups in the microspheres. Four-step titration curves of all the P(NIPAM-co-AAc)microspheres with different acrylic acid contents were obtained. With the increase of AAc content, the amounts of both exterior carboxyl and embeded carboxyl groups increased gradually, but the percentage of exterior carboxyl groups increased firstly, then remained at a fixed value. The highest percentage of exterior carboxyl groups was obtained with 15%(ω) acrylic acid in the microspheres.%采用膜乳化法,以环己烷和氯仿混合溶液为油相,在室温下通过加入加速剂TEMED引发聚合反应,制备了一系列不同内烯酸含量的P(NIPAM-co-AAc)微球.结果表明,在压力2 kPa、环己烷/氯仿体积比7:3、第一和第二阶段过膜搅拌速度分别为140和170 r/min的条件下,可制备粒径均一、大小可控、重复性较好的P(NlPAM-co-AAc)微球.用电导滴定法测定微球中羧基分布,所有不同丙烯酸含量的P(NIPAM-co-AAc)微球电导滴定曲线均为4阶梯形状,随其含量增加,微球外层羧基含量和内层包埋的羧基含量均逐渐增加,但外层羧基占总羧基含量比例先增大然后趋于不变,丙烯酸含量为15%时达最大值.

  17. Self-Templated Stepwise Synthesis of Monodispersed Nanoscale Metalated Covalent Organic Polymers for In Vivo Bioimaging and Photothermal Therapy.

    Science.gov (United States)

    Shi, Yanshu; Deng, Xiaoran; Bao, Shouxin; Liu, Bei; Liu, Bin; Ma, Ping'an; Cheng, Ziyong; Pang, Maolin; Lin, Jun

    2017-07-10

    Size- and shape-controlled growth of nanoscale microporous organic polymers (MOPs) is a big challenge scientists are confronted with; meanwhile, rendering these materials for in vivo biomedical applications is still scarce. In this study, a monodispersed nanometalated covalent organic polymer (MCOP, M=Fe, Gd) with sizes around 120 nm was prepared by a self-templated two-step solution-phase synthesis method. The metal ions (Fe(3+) , Gd(3+) ) played important roles in generating a small particle size and in the functionalization of the products during the reaction with p-phenylenediamine (Pa). The resultant Fe-Pa complex was used as a template for the subsequent formation of MCOP following the Schiff base reaction with 1,3,5-triformylphloroglucinol (Tp). A high tumor suppression efficiency for this Pa-based COP is reported for the first time. This study demonstrates the potential use of MCOP as a photothermal agent for photothermal therapy (PTT) and also provides an alternative route to fabricate nano-sized MCOPs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Evaporative purification to produce highly monodisperse polymers: Application to polystyrene for n =3 -13 and quantification of Tg from oligomer to polymer

    Science.gov (United States)

    Zhu, S.; Chai, Y.; Forrest, J. A.

    2017-07-01

    We demonstrate the use of selective thermal evaporation to separate and purify small molecular weight polymers into highly monodisperse polymers over an extended range of polymerization index. By exploiting the calculated dependence of polymer vapor pressure on polymerization index N and temperature T , we can isolate individual components (N -mers) of an initially polydisperse mixture. To demonstrate this ability, we consider polystyrene samples of Mw=600 g/mol and Mw=890 g/mol with narrow molecular weight distributions, as well as a Mw=1200 g/mol sample with a broader distribution. In each case we are able to separate the sample into milligram quantities of many different components. Using this technique, we have been able to isolate N -mers from 3 to 13. We use differential scanning calorimetry to measure the Tg values of these components, and find that the components have the same Tg values independent of the Mw or polydispersity of the sample they originate from. We find that even initially narrow molecular weight distributions have many different components whose Tg values can differ by more than 50 K. Calculations suggest the isolated components have Mw/Mn values less than 1.001 and through a second iteration of the process could become as low as 1.000 003. The measured Tg values for the N -mers as well as large N polymers are well described by a simple relation derived from the Fox equation for the Tg of mixtures.

  19. Preparation and evaluation of biodegradable microspheres containing a new potent osteogenic compound and new synthetic polymers for sustained release.

    Science.gov (United States)

    Umeki, Nobuo; Sato, Takayuki; Harada, Masahiro; Takeda, Junko; Saito, Shuji; Iwao, Yasunori; Itai, Shigeru

    2010-06-15

    In order to achieve the sustained release of 3-ethyl-4-(4-methylisoxazol-5-yl)-5-(methylthio) thiophene-2-carboxamide (BFB0261), a new potent osteogenic compound for the treatment of bone disorders, we prepared microspheres containing BFB0261 and newly synthesized three poly (D, L-lactic acid) (PLA), four poly (D, L-lactic acid-co-glycolic acid) (PLGA), and eight poly (D, L-lactic acid)-block-poly(ethylene glycol) (PLA-PEG) biodegradable polymers or copolymers, and evaluated the release pattern of BFB0261 from the microspheres in vitro and in vivo. The mean particle size of the microspheres, except for the microspheres constructed from PLA-PEG with a greater than 20% PEG component, was in the range of approximately 10-50 microm, and the preparations showed a spherical shape with a smooth surface. In an in vitro release study, the release of BFB0261 from PLA-1 (Mw: 36 kDa), PLAPEG9604H (PLA/PEG ratio: 96:4, Mw: 181 kDa), or PLAPEG8317 (PLA/PEG ratio: 83:17, Mw: 106 kDa) microspheres occurred in a zero-order manner with a slow release, and more than 50% of BFB0261 remained in each type of microsphere at 12 weeks after incubation. When the BFB0261 microspheres constructed from various polymers were intramuscularly administered to the rat femur, the microspheres constructed from PLA-1 or PLAPEG9604H were able to achieve a sustained release of BFB0261 at the injection site for 6 weeks. The present information indicates that microspheres constructed from PLA-1 or PLAPEG9604H may be feasible for bone engineering. Copyright 2010 Elsevier B.V. All rights reserved.

  20. Controlled release metformin hydrochloride microspheres of ethyl cellulose prepared by different methods and study on the polymer affected parameters.

    Science.gov (United States)

    Choudhury, Pratim K; Kar, Mousumi

    2009-02-01

    The objectives of this investigation were to prepare microspheres of the anti-diabetic drug, metformin hydrochloride, using ethyl cellulose as the polymer and evaluate the encapsulation efficiency and release characteristics in vitro and in vivo; utilizing different microencapsulation techniques. Different proportions of polymer were used to obtain varying drug-polymer ratios. Physical properties, loading efficiency and dissolution rate were dependent on the method chosen for preparation and also on the drug-to-polymer ratio. The addition of surfactant during emulsification and petroleum ether in non-solvent addition process affected release of drug and also size distribution of microspheres. To investigate the type of mechanism that occurs, dissolution data were plotted according to different kinetic models. In vitro release studies show first order and Higuchi model release characteristics being exhibited. All the results were treated statistically to validate the findings. Significant differences in percentage yield, entrapment efficiency and sustaining capacity were seen with microspheres prepared by two different methods. In vivo studies in normal and hyperglycemic mice show faster glucose reduction with microspheres prepared by the evaporation method, whereas the release sustaining effect was more pronounced with microspheres prepared by the non-solvent addition method.

  1. Microfluidic Fabrication of Porous Polymer Microspheres: Dual Reactions in Single Droplets

    KAUST Repository

    Gong, Xiuqing

    2009-06-16

    We report the microfluidic fabrication of macroporous polymer microspheres via the simultaneous reactions within single droplets, induced by LTV irradiation. The aqueous phase of the reaction is the decomposition of H 2O2 to yield oxygen, whereas the organic phase is the polymerization of NO A 61, ethylene glycol dimethacrylate (EGDMA), and tri (propylene glycol) diacrylate (TPGDA) precursors. We first used a liquid polymer precursor to encapsulate a multiple number of magnetic Fe3O 4 colloidal suspension (MCS) droplets in a core-shell structure, for the purpose of studying the number of such encapsulated droplets that can be reliably controlled through the variation of flow rates. It was found that the formation of one shell with one, two, three, or more encapsulated droplets is possible. Subsequently, the H2O2 solution was encapsulated in the same way, after which we investigated its decomposition under UV irradiation, which simultaneously induces the polymerization of the encapsulating shell. Because the H2O2 decomposition leads to the release of oxygen, porous microspheres were obtained from a combined H2O2 decomposition/polymer precursor polymerization reaction. The multiplicity of the initially encapsulated H2O 2 droplets ensures the homogeneous distribution of the pores. The pores inside the micrometer-sized spheres range from several micrometers to tens of micrometers, and the maximum internal void volume fraction can attain 70%, similar to that of high polymerized high internal phase emulsion (polyHIPE). © 2009 American Chemical Society.

  2. Prediction of dexamethasone release from PLGA microspheres prepared with polymer blends using a design of experiment approach.

    Science.gov (United States)

    Gu, Bing; Burgess, Diane J

    2015-11-10

    Hydrophobic drug release from poly (lactic-co-glycolic acid) (PLGA) microspheres typically exhibits a tri-phasic profile with a burst release phase followed by a lag phase and a secondary release phase. High burst release can be associated with adverse effects and the efficacy of the formulation cannot be ensured during a long lag phase. Accordingly, the development of a long-acting microsphere product requires optimization of all drug release phases. The purpose of the current study was to investigate whether a blend of low and high molecular weight polymers can be used to reduce the burst release and eliminate/minimize the lag phase. A single emulsion solvent evaporation method was used to prepare microspheres using blends of two PLGA polymers (PLGA5050 (25 kDa) and PLGA9010 (113 kDa)). A central composite design approach was applied to investigate the effect of formulation composition on dexamethasone release from these microspheres. Mathematical models obtained from this design of experiments study were utilized to generate a design space with maximized microsphere drug loading and reduced burst release. Specifically, a drug loading close to 15% can be achieved and a burst release less than 10% when a composition of 80% PLGA9010 and 90 mg of dexamethasone is used. In order to better describe the lag phase, a heat map was generated based on dexamethasone release from the PLGA microsphere/PVA hydrogel composite coatings. Using the heat map an optimized formulation with minimum lag phase was selected. The microspheres were also characterized for particle size/size distribution, thermal properties and morphology. The particle size was demonstrated to be related to the polymer concentration and the ratio of the two polymers but not to the dexamethasone concentration.

  3. Surface modification of imprinted polymer microspheres with ultrathin hydrophilic shells to improve selective recognition of glutathione in aqueous media.

    Science.gov (United States)

    Song, Renyuan; Hu, Xiaoling; Guan, Ping; Li, Ji; Du, Chunbao; Qian, Liwei; Wang, Chaoli

    2016-03-01

    A universal, effective approach addressing the classical limitations of hydrophobic molecularly imprinted polymer (MIP) microspheres was described. Two water-compatible MIP microspheres with ultrathin hydrophilic shells were synthesized by controllable surface-graft polymerization using a charged monomer (methacrylic acid) and uncharged monomer (N-isopropylacrylamide) as the hydrophilic functional monomers for the recognition of glutathione in the aqueous medium. The morphological and chemical characteristics of the as-prepared water-compatible MIP microspheres were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy and contact angle measurements. Their selective recognition properties were investigated by static binding tests and compared with those of the ungrafted MIP microspheres. The results of this study showed that the both as-prepared water-compatible MIP microspheres effectively decreased non-specific binding and enhanced the imprinting factor significantly, and the water-compatible MIP microspheres prepared using N-isopropylacrylamide as monomer exhibited a more remarkable recognition property. In addition, the thickness of surface-grafted hydrophilic layer was well controlled by adjusting the irradiation time to obtain the excellent recognition property. Finally, the applicability of the as-prepared water-compatible MIP microspheres as solid-phase extraction materials was investigated by competitive binding tests using a mixture of glutathione and its analogs.

  4. Synthesis and Characterization of Molecular Imprinting Polymer Microspheres of Piperine: Extraction of Piperine from Spiked Urine

    Directory of Open Access Journals (Sweden)

    Rachel Marcella Roland

    2016-01-01

    Full Text Available Molecularly imprinted polymer (MIP microspheres for Piperine were synthesized by precipitation polymerization with a noncovalent approach. In this research Piperine was used as a template, acrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, and 2,2′-azobisisobutyronitrile (AIBN as an initiator and acetonitrile as a solvent. The imprinted and nonimprinted polymer particles were characterized by using Fourier transform infrared spectroscopy (FT-IR and Scanning Electron Microscopy (SEM. The synthesized polymer particles were further evaluated for their rebinding efficiency by batch binding assay. The highly selected imprinted polymer for Piperine was MIP 3 with a composition (molar ratio of 0.5 : 3 : 8, template : monomer : cross-linker, respectively. The MIP 3 exhibits highest binding capacity (84.94% as compared to other imprinted and nonimprinted polymers. The extraction efficiency of highly selected imprinted polymer of Piperine from spiked urine was above 80%.

  5. NARROW-DISPERSED CROSSLINKED CORE-SHELL POLYMER MICROSPHERES PREPARED BY SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Yu-zeng Zhao; Xin-lin Yang; Feng Bai; Wen-qiang Huang

    2005-01-01

    Grafting of polystyrene with narrowly dispersed polymer microspheres through surface-initiated atom transfer radical polymerization (ATRP) was investigated. Polydivinylbenzene (PDVB) microspheres were prepared by dispersion polymerization with poly(N-vinyl pyrrolidone) (PVP) as stabilizer. The surfaces of PDVB microspheres were chloromethylated by chloromethyl methyl ether in the presence of zinc chloride as catalyst to form chloromethylbenzene initiating core sites for subsequent ATRP grafting of styrene using CuC1/bpy as catalytic system. Polystyrene was found to be grafted not only from the particle surfaces but also from within a thin shell layer, resulting in the formation of particles size increased from 2.38-2.58 μm, which can further grow to 2.93 μm during secondary grafting polymerization of styrene. This demonstrates that grafting polymerization proceeds through a typical ATRP procedure with living nature. All of the prepared microspheres have narrow particle size distribution with coefficient of variation around 10%.

  6. Crystallisation and structural studies of monodisperse nylon oligomers and related polymers

    CERN Document Server

    Sikorski, P T

    2001-01-01

    Examination of the chain conformation for this phase shows that most of peptide units have backbone torsional angles around 60 deg away from the beta-conformation. When this liquid-crystalline phase was partially dried, it transformed into metastable phase, described in the literature as silk I. The properties of this silk I phase are discussed. of hydrogen-bonded sheet formed by these molecules can influence the way in which these sheets stack to form crystals. In addition, a study of the 9-amide molecule showed that a particular type of hydrogen-bonded sheet, a-sheet, is preferred for nylon 4 6. This discovery suggests that an amide unit is found in the fold in the chain-folded nylon 4 6 polymer crystals, to allow the a-sheets to be formed. It is not a consequence of a need to form a stress-free fold. In the regular adjacent re-entry chain-folded crystals, one amide unit must be removed from straight-stems in order for the a-sheets to be formed. For the 4-amide nylon 4 6 molecule changes in the unit cell on...

  7. Release and pharmacokinetics of near-infrared labeled albumin from monodisperse poly(D,L-lactic-co-hydroxymethyl glycolic acid) microspheres after subcapsular renal injection

    NARCIS (Netherlands)

    Kazazi-Hyseni, F.; Van Vuuren, S. H.; Van Der Giezen, D. M.; Pieters, E. H.; Ramazani, F.; Rodriguez, S.; Veldhuis, G. J.; Goldschmeding, R.; Van Nostrum, C. F.; Hennink, W. E.; Kok, R. J.

    2015-01-01

    Subcapsular renal injection is a novel administration method for local delivery of therapeutics for the treatment of kidney related diseases. The aim of this study was to investigate the feasibility of polymeric microspheres for sustained release of protein therapeutics in the kidney and study the s

  8. High Ionic Conductivity of Composite Solid Polymer Electrolyte via In Situ Synthesis of Monodispersed SiO2 Nanospheres in Poly(ethylene oxide).

    Science.gov (United States)

    Lin, Dingchang; Liu, Wei; Liu, Yayuan; Lee, Hye Ryoung; Hsu, Po-Chun; Liu, Kai; Cui, Yi

    2016-01-13

    High ionic conductivity solid polymer electrolyte (SPE) has long been desired for the next generation high energy and safe rechargeable lithium batteries. Among all of the SPEs, composite polymer electrolyte (CPE) with ceramic fillers has garnered great interest due to the enhancement of ionic conductivity. However, the high degree of polymer crystallinity, agglomeration of ceramic fillers, and weak polymer-ceramic interaction limit the further improvement of ionic conductivity. Different from the existing methods of blending preformed ceramic particles with polymers, here we introduce an in situ synthesis of ceramic filler particles in polymer electrolyte. Much stronger chemical/mechanical interactions between monodispersed 12 nm diameter SiO2 nanospheres and poly(ethylene oxide) (PEO) chains were produced by in situ hydrolysis, which significantly suppresses the crystallization of PEO and thus facilitates polymer segmental motion for ionic conduction. In addition, an improved degree of LiClO4 dissociation can also be achieved. All of these lead to good ionic conductivity (1.2 × 10(-3) S cm(-1) at 60 °C, 4.4 × 10(-5) S cm(-1) at 30 °C). At the same time, largely extended electrochemical stability window up to 5.5 V can be observed. We further demonstrated all-solid-state lithium batteries showing excellent rate capability as well as good cycling performance.

  9. Surface modification of imprinted polymer microspheres with ultrathin hydrophilic shells to improve selective recognition of glutathione in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Song, Renyuan, E-mail: songrenyuan0726@163.com; Hu, Xiaoling; Guan, Ping; Li, Ji; Du, Chunbao; Qian, Liwei; Wang, Chaoli

    2016-03-01

    A universal, effective approach addressing the classical limitations of hydrophobic molecularly imprinted polymer (MIP) microspheres was described. Two water-compatible MIP microspheres with ultrathin hydrophilic shells were synthesized by controllable surface-graft polymerization using a charged monomer (methacrylic acid) and uncharged monomer (N-isopropylacrylamide) as the hydrophilic functional monomers for the recognition of glutathione in the aqueous medium. The morphological and chemical characteristics of the as-prepared water-compatible MIP microspheres were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy and contact angle measurements. Their selective recognition properties were investigated by static binding tests and compared with those of the ungrafted MIP microspheres. The results of this study showed that the both as-prepared water-compatible MIP microspheres effectively decreased non-specific binding and enhanced the imprinting factor significantly, and the water-compatible MIP microspheres prepared using N-isopropylacrylamide as monomer exhibited a more remarkable recognition property. In addition, the thickness of surface-grafted hydrophilic layer was well controlled by adjusting the irradiation time to obtain the excellent recognition property. Finally, the applicability of the as-prepared water-compatible MIP microspheres as solid-phase extraction materials was investigated by competitive binding tests using a mixture of glutathione and its analogs. - Highlights: • Ultrathin hydrophilic shell was synthesized by controllable SIP approach. • Low nonspecific binding, high imprinting factor and selectivity were achieved. • Value of imprinting factor was controlled by adjusting irradiation time. • Selective solid-phase extraction of glutathione from a mixed solution of peptides.

  10. 单分散间苯二酚-甲醛气凝胶微球的制备工艺%Preparation of Monodisperse Resorcinol-formaldehyde Aerogel Microspheres

    Institute of Scientific and Technical Information of China (English)

    侯海乾; 王朝阳; 唐永建; 付志兵; 周莹

    2009-01-01

    采用T型微流体注射成型技术,以邻苯二甲酸二丁酯、液体石蜡和司班80为油相,间苯二酚/甲醛(RF)溶液为水相,经过溶胶-凝胶、溶剂交换、超临界干燥等过程制备了单分散RF气凝胶微球,并就制备过程中RF溶液与分散剂油相的选择、预聚时间、流速比、搅拌速率、固化温度等影响因素进行了初步讨论.当RF溶液质量分数为10%,60℃预聚1.5 h,间苯二酚与碳酸钠的物质的量之比为100,邻苯二甲酸二丁酯与液体石蜡的质量比为8:1,流速比控制在8~16,搅拌速率为65~90r/min,固化温度为35℃时,制备得到了RF乳液,其粒径分布系数小于2%.%Based on a novel T-shaped microfluidic device, monodisperse RF aerogel microspheres are prepared by using dibutyl phthalate,atoleine and span 80 as oil phase, RF solution as water phase, and by sol-gel, solvent exchanging and supercritical drying. The factors such as the choice of RF solution and oil, prepolymerization time, the flow rate ratio of oil to water phase, stirring rate and solidification temperature, which affect the process have been preliminarily discussed. When the polymerization reaction occur in the following conditions: RF solution is 10% ,prepolymerization time is 1. 5 hours at 60℃, the molar ratio of resorcinol to sodium carbonate is 100, the mass ratio of dibutyl phthalate to atoleine is 8,the flow rate ratio of oil to water phase is 8-16, stirring rate is 65~90r/min and solidification temperature is 35℃, the experiment has fabricated monodisperse RF aerogel microspheres, whose coefficient of variation (CV value) of all the RF droplets is below 2% .

  11. Preparation, Characterization of Monodisperse Polysiloxane Microspheres and Its Application as Light Scattering Agents%单分散聚硅氧烷微球的制备表征及作为光散射剂的应用

    Institute of Scientific and Technical Information of China (English)

    马文石; 张冬桥; 段宇; 万兆荣; 王洪; 徐迎宾

    2012-01-01

    以乳液聚合法制备粒径分布均匀、球形度良好的聚硅氧烷微球。采用扫描电镜(SEM)、动态光散射(DLS)、红外光谱(FT-IR)、X射线衍射(XRD)、热重分析(TGA)和接触角等测试技术对微球的微观形貌、粒径大小及分布、聚集态结构、耐热性、疏水性等进行了表征。将平均粒径为1.5μm的聚硅氧烷微球作为光散射剂添加到光学级聚甲基丙烯酸甲酯(PMMA)树脂中,可制备出性能优良的光散射材料。当聚硅氧烷微球添加质量分数约0.6%时,光散射材料的透光率是86.1%,雾度是91.25%,拉伸强度达到最大值77.2 MPa,弯曲强度是87.2 MPa,简支梁缺口冲击强度是2.16 kJ/m2,悬臂梁缺口冲击强度是2.71 kJ/m2,综合性能良好。%Highly uniform and monodisperse polysiloxane microspheres were prepared by emulsion polymeration.The morphology,size distribution,and state of aggregation were characterized by SEM,dynamic light scattering(DLS),FT-IR and XRD.The thermodecomposition and hydrophobicity of these microspheres were investigated with TGA and water contact angle measurement.Light scattering material with excellent performance could be prepared by blending polysiloxane microspheres(the average size of 1.5 μm) with optical-grade polymethylmethacylate(PMMA).When the mass fraction of microspheres is about 0.6%,the transmittance of composite material is 86.1% and the haze is 91.25%,the tensile strength reaches its maximum,namely 77.2 MPa,the bending strength is 87.2 MPa,the charpy notched impact strength is 2.16 kJ/m^2,the Izod notched impact strength is 2.71 kJ/m^2.The comprehensive properties of the composite material are excellent.

  12. Engineered monodisperse mesoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Saunders, R.S.; Small, J.H.; Lagasse, R.R.; Schroeder, J.L.; Jamison, G.M.

    1997-08-01

    Porous materials technology has developed products with a wide variety of pore sizes ranging from 1 angstrom to 100`s of microns and beyond. Beyond 15{angstrom} it becomes difficult to obtain well ordered, monodisperse pores. In this report the authors describe efforts in making novel porous material having monodisperse, controllable pore sizes spanning the mesoporous range (20--500 {angstrom}). They set forth to achieve this by using unique properties associated with block copolymers--two linear homopolymers attached at their ends. Block copolymers phase separate into monodisperse mesophases. They desired to selectively remove one of the phases and leave the other behind, giving the uniform monodisperse pores. To try to achieve this the authors used ring-opening metathesis polymerization to make the block copolymers. They synthesized a wide variety of monomers and surveyed their polymers by TGA, with the idea that one phase could be made thermally labile while the other phase would be thermally stable. In the precipitated and sol-gel processed materials, they determined by porosimetry measurements that micropores, mesopores, and macropores were created. In the film processed sample there was not much porosity present. They moved to a new system that required much lower thermal treatments to thermally remove over 90% of the labile phase. Film casting followed by thermal treatment and solvent extraction produced the desired monodisperse materials (based solely on SEM results). Modeling using Density Functional Theory was also incorporated into this project. The modeling was able to predict accurately the domain size and spacing vs. molecular weight for a model system, as well as accurate interfacial thicknesses.

  13. Preparation and Characterization in vitro of Sustained-release Captopril/Chitosan-gelatin Net-polymer Microspheres(Cap/CGNPMs)

    Institute of Scientific and Technical Information of China (English)

    SONG Yimin; CHEN Xiguang; TANG Xuexi; LIU Chengshen; MENG Xianghong; YU Luojun

    2006-01-01

    The captopril/Chitosan-gelatin net-polymer microspheres (Cap/CGNPMs) were prepared using Chitosan(CS) and gelatin(Gel) by the methods of emulsification. A cross linked reagent alone or in combination with microcrystalline cellulose(MCC) was added in the process of preparation of microspheres to eliminate dose dumping and burst phenomenon of microspheres for the improvement of the therapeutic efficiency and the decrease of the side effects of captopril(Cap). The results indicate that Cap/CGNPMs have a spherical shape , smooth surface morphology and integral inside structure and no adhesive phenomena and good mobility,and the size distribution is mainly from 220 to 280 μm. Researches on the Cap release test in vitro demonstrate that Cap/CGNPMs are of the role of retarding release of Cap compared with Cap ordinary tablets (COT), embedding ratio (ER) ,drug loading (DL), and swelling ratio (SR), and release behaviors of CGNPMS are influenced by process conditions of preparation such as experimental material ratio (EMR) , composition of cross linking reagents. Among these factors , the EMR(1/4),CLR (FOR+TPP) and 0.75% microcrystalline cellulose (MCC) added to the microspheres are the optimal scheme to the preparation of Cap/CGNPMs. The Cap/CGNPMs have a good characteristic of sustained release of drug, and the process of emulsification and cross-linking process is simple and stable. The CGNPMs is probable to be one of an ideal sustained release system for water-soluble drugs.

  14. Cross-linked branching nanohybrid polymer electrolyte with monodispersed TiO2 nanoparticles for high performance lithium-ion batteries

    Science.gov (United States)

    Ma, Cheng; Zhang, Jinfang; Xu, Mingquan; Xia, Qingbing; Liu, Jiatu; Zhao, Shuai; Chen, Libao; Pan, Anqiang; Ivey, Douglas G.; Wei, Weifeng

    2016-06-01

    Nanohybrid polymer electrolytes (NHPE) with ceramic particles have attracted significant attention owing to their improvement in electrochemical performance. However, particle aggregation and weak nanoparticle/polymer matrix interaction restrict their further application in lithium-ion batteries (LIBs). We demonstrate a facile in-situ polymerization/crystallization method to synthesize a homogeneous TiO2-grafted NHPE with a cross-linked branching structure, comprised of ion-conducting poly(ethylene glycol) methyl ether methacrylate (PEGMEM) and non-polar stearyl methacrylate (SMA). This technique is different from existing methods of blending functionalized ceramic particles into the polymer matrix. Highly monodispersed TiO2 nanocrystals enhance the effective interfacial interactions between particles and polymer matrix, which suppress the crystallization of ethylene oxide (EO) groups and facilitate forming continuously interconnected ion-conducting channels. Moreover, an increased dissociation degree of Li salt can also be achieved. The TiO2-grafted NHPE exhibits superior electrochemical properties with an ionic conductivity of 1.1 × 10-4 S cm-1 at 30 °C, a high lithium ion transference number and excellent interfacial compatibility with the lithium electrode. In particular, a lithium-ion battery based on TiO2-grafted NHPE demonstrates good C-rate performance, as well as excellent cycling stability with an initial discharge capacity of 153.5 mAh g-1 and a capacity retention of 96% after 300 cycles at 1 C (80 °C).

  15. Characterization of Fe3O4/P(St-MPEO) Amphiphilic Magnetic Polymer Microspheres

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Amphiphilic magnetic microspheres consisting of styrene and poly(ethylene oxide) macromonomer(MPEO) were prepared by dispersion copolymerization in the presence of Fe3O4 magnetic fluid in an ethanol/water medium. The sizes of the magnetic microspheres and their distribution were characterized by means of scanning electron microscopy(SEM). The surface morphology and the average surface roughness of the microspheres were investigated by virtue of atomic force microscopy(AFM). It was found that the microspheres exhibit microscopic phase-separate and the mean square surface roughness of the microspheres increases with increasing MPEO used in the copolymerization. The amphiphilic magnetic microspheres containing 0.4-3.5 mg/g hydroxyl groups could be prepared from MPEO with different concentrations and styrene.

  16. Cellulose acetate butyrate-pH/thermosensitive polymer microcapsules containing aminated poly(vinyl alcohol) microspheres for oral administration of DNA.

    Science.gov (United States)

    Fundueanu, Gheorghe; Constantin, Marieta; Bortolotti, Fabrizio; Cortesi, Rita; Ascenzi, Paolo; Menegatti, Enea

    2007-04-01

    The aim of this work is to safely transport bioadhesive microspheres loaded with DNA to intestine and to test their bioadhesive properties. Poly(vinyl alcohol) (PVA) microspheres were prepared by dispersion reticulation with glutaraldehyde and further aminated. These microspheres were firstly loaded with plasmid DNA by electrostatic interactions and then entrapped in cellulose acetate butyrate (CAB) microcapsules for gastric protection. The entrapped PVA microspheres do not have enough force by swelling to produce the rupture of CAB shell, therefore the resistance of microcapsules was weakened by incorporating different amount of the pH/thermosensitive polymer (SP) based on poly(N-isopropylacrylamide-co-methyl methacrylate-co-methacrylic acid) (NIPAAm-co-MM-co-MA). This polymer is insoluble in gastric juice at pH 1.2 and 37 degrees C, but quickly solubilized in intestinal fluids (pH 6.8 and pH 7.4). Therefore, DNA loaded PVA microspheres were not expelled in acidic media but were almost entirely discharged in small intestine or colon. The integrity of DNA after entrapment was tested by agarose gel electrophoresis indicating that no DNA degradation occurs during encapsulation. The percentage of adhered microspheres on the mucus surface of everted intestinal tissue was 65+/-18% for aminated PVA microspheres without DNA and almost 50+/-15% for those loaded with DNA. Non-aminated PVA microspheres display the lowest adhesive properties (33+/-12%). In conclusion DNA loaded microspheres were progressively discharged in intestine. The integrity of DNA was not modified after entrapment and release, as proved by agarose gel electrophoresis. Both loaded and un-loaded aminated microspheres display good bioadhesive properties.

  17. Controllable assembly of well-defined monodisperse Au nanoparticles on hierarchical ZnO microspheres for enhanced visible-light-driven photocatalytic and antibacterial activity

    Science.gov (United States)

    Wang, Yuan; Fang, Hua-Bin; Zheng, Yan-Zhen; Ye, Rongqin; Tao, Xia; Chen, Jian-Feng

    2015-11-01

    A high-efficiency visible-light-driven photocatalyst composed of homogeneously distributed Au nanoparticles (AuNPs) well-defined on hierarchical ZnO microspheres (ZMS) via a controllable layer-by-layer self-assembly technique is demonstrated. The gradual growth of the characteristic absorption bands of Au loaded on ZnO in the visible light region with an increasing number of assemblies indicates the enhancement of the light harvesting ability of the ZMS/Au composites as well as the reproducibility and controllability of the entire assembly process. Results on the photoelectrochemical performance characterized by EIS and transient photocurrent response spectra indicate that the ZMS/Au composites possess increased photoinduced charge separation and transfer efficiency compared to the pure ZMS film. As a result, the hybrid composites exhibited enhanced decomposition activity for methylene blue and salicylic acid as well as antibacterial activity in killing S. aureus and E. coli under visible light irradiation. It can be noted that well-distributed Au components even at a rather low Au/ZnO weight ratio of ~1.2% also exhibited extraordinary photocatalysis. Such a facile and controllable self-assembly approach may be viable for preparing high-performance visible-light-driven ZMS/Au photocatalysts in a simple and controllable way, and consequently, the technology may extend to other plasmon-enhanced heterostructures made of nanostructured semiconductors and noble metals for great potential application in environmental protection.A high-efficiency visible-light-driven photocatalyst composed of homogeneously distributed Au nanoparticles (AuNPs) well-defined on hierarchical ZnO microspheres (ZMS) via a controllable layer-by-layer self-assembly technique is demonstrated. The gradual growth of the characteristic absorption bands of Au loaded on ZnO in the visible light region with an increasing number of assemblies indicates the enhancement of the light harvesting ability of

  18. Chromatographic comparison of bupivacaine imprinted polymers prepared in crushed monolith, microsphere, silica-based composite and capillary monolith formats.

    Science.gov (United States)

    Oxelbark, Joakim; Legido-Quigley, Cristina; Aureliano, Carla S A; Titirici, Maria-Magdalena; Schillinger, Eric; Sellergren, Börje; Courtois, Julien; Irgum, Knut; Dambies, Laurent; Cormack, Peter A G; Sherrington, David C; De Lorenzi, Ersilia

    2007-08-10

    A comprehensive comparison of five chromatographic stationary phases based on molecularly imprinted polymers is presented. Efficiency, imprinting factors, water compatibility and batch-to-batch reproducibility are discussed for crushed monolith, microspheres, two silica-based composites and capillary monoliths, all imprinted with the local anaesthetic bupivacaine. Synthesis protocol and chromatographic test conditions have been kept fixed within certain limits, in order to provide further insight into the strengths and weaknesses of the different formats. Excluding microparticles, all formats give satisfactory performance, especially in aqueous mobile phases. An assessment of batch-to-batch reproducibility in different mobile phases adds further value to this comparison study.

  19. Preparation and in vitro release performance of sustained-release captopril/Chitosan-gelatin net-polymer microspheres

    Science.gov (United States)

    Zhou, Li; Xu, Junming; Song, Yimin; Gao, Yuanyuan; Chen, Xiguang

    2007-07-01

    The captopril/Chitosan-gelatin net-polymer microspheres (CTP/CGNPMs) were prepared using Chitosan (CTS) and gelatin (GT) by the methods of emulsification, cross-linked reagent alone or in combination and microcrystalline cellulose (MCC) added in the process of preparation of microspheres, which aimed to eliminate dose dumping and burst phenomenon of microspheres for the improvement of the therapeutic efficiency and the decrease of the side effects of captopril (CTP). The results indicated that CTP/CGNPMs had a spherical shape, smooth surface and integral structure inside but no adhesive phenomena in the preparation. The size distribution ranged from 220 μm to 280 μm. The CTP release test in vitro demonstrated that CTP/CGNPMs played the role of retarding the release of CTP compared with ordinary CTP tablets. The release behaviors of CGNPMS were influenced by preparation conditions such as experimental material ratio (EMR) and composition of cross linking reagents. Among these factors, the EMR (1/4), CLR (FA+SPP) and 0.75% microcrystalline cellulose (MCC) added to the microspheres constituted the optimal scheme for the preparation of CTP/CGNPMs. The ER, DL and SR of CTP/CGNPMs prepared according to the optimal scheme were 46.23±4.51%, 9.95±0.77% and 261±42%, respectively. The CTP/CGNPMs had the good characteristics of sustained release of drug and the process of emulsification and cross-linking were simple and stable. The CGNPMs are likely to be an ideal sustained release formulation for water-soluble drugs.

  20. Preparation and in vitro Release Performance of Sustained-release Captopril/Chitosan-gelatin Net-polymer Microspheres

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The captopril/Chitosan-gelatin net-polymer microspheres (CTP/CGNPMs) were prepared using Chitosan (CTS) and gelatin (GT) by the methods of emulsification, cross-linked reagent alone or in combination and microcrystalline cellulose (MCC) added in the process of preparation of microspheres, which aimed to eliminate dose dumping and burst phenomenon of microspheres for the improvement of the therapeutic efficiency and the decrease of the side effects of captopril (CTP). The results indicated that CTP/CGNPMs had a spherical shape, smooth surface and integral structure inside but no adhesive phenomena in the preparation. The size distribution ranged from 220 μm to 280 μm. The CTP release test in vitro demonstrated that CTP/CGNPMs played the role of retarding the release of CTP compared with ordinary CTP tablets. The release behaviors of CGNPMS were influenced by preparation conditions such as experimental material ratio (EMR) and composition of cross linking reagents. Among these factors, the EMR (1/4), CLR (FA+SPP) and 0.75% microcrystalline cellulose (MCC) added to the microspheres constituted the optimal scheme for the preparation of CTP/CGNPMs. The ER, DL and SR of CTP/CGNPMs prepared according to the optimal scheme were 46.23±4.51%, 9.95±0.77% and 261±42%, respectively. The CTP/CGNPMs had the good characteristics of sustained release of drug and the process of emulsification and cross-linking were simple and stable. The CGNPMs are likely to be an ideal sustained release formulation for water-soluble drugs.

  1. PREPARATION OF POLY(ETHYLENEGLYCOL-co-ACRYLIC ACID) MICROSPHERES WITH DIVINYLBENZNE AS CROSSLINKER BY DISTILLATION-PRECIPITATION POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Zhao Dai; Xin-lin Yang; Wen-qiang Huang

    2007-01-01

    Monodisperse poly(poly(ethyleneglycol) methyl ether acrylate-co-acrylic acid) (poly(PEGMA-co-AA))microspheres were prepared by distillation-precipitation polymerization with divinylbenzene (DVB) as crosslinker with 2,2'-azobisisobutyronitrile (AIBN) as initiator in neat acetonitrile without stirring. Under various reaction conditions, four distinct morphologies including the sol, microemulsion, microgels and microspheres were formed during the distillation of the solvent from the reaction system. A 2D morphological map was established as a function of crosslinker concentration and the polar monomer AA concentration, in comonomer feed in the transition between the morphology domains. The effect of the covalent crosslinker DVB on the morphology of the polymer network was investigated in detail at AA fraction of 40 vol%.The ratios of acid to ethylene oxide units presenting in the comonomers dramatically affected the polymer-polymer interaction and hence the morphology of the resultant polymer network. The covalent crosslinking by DVB and the hydrogen bonding crosslinking between two acid units as well as between the acid and ethylene oxide unit played key roles in the formation of monodisperse polymer microspheres.

  2. Removal of Chromium(VI from Aqueous Solutions Using Fe3O4 Magnetic Polymer Microspheres Functionalized with Amino Groups

    Directory of Open Access Journals (Sweden)

    Kai Wang

    2015-12-01

    Full Text Available Magnetic polymer microspheres (MPMs using glycidylmethacrylate (GMA as a functional monomer were synthesized in the presence of Fe3O4 nanoparticles via dispersion polymerization. After polymerization, the magnetic polymer microbeads were modified with ethylenediamine (EDA. The obtained ethylenediamine-functionalized magnetic microspheres (EDA-MPMs were characterized by scanning electron microscope (SEM, X-ray diffraction (XRD, vibrating-sample magnetometer (VSM and Fourier transform infrared (FT-IR spectroscopy. Then the EDA-MPMs were applied as adsorbents for the removal of Cr(VI from aqueous solution. Langmuir equation was appropriate to describe the experimental data. The maximum adsorption capacities obtained from the Langmuir model were 236.9, 242.1 and 253.2 mg/g at 298, 308 and 318 K, respectively. The Cr(VI adsorption equilibrium was established within 120 min and the adsorption kinetics was compatibly described by the pseudo-second order equation. The thermodynamic parameters (ΔG°, ΔH°, ΔS° of the sorption process revealed that the adsorption was spontaneous and was an endothermic process. The regeneration study demonstrated that the EDA-MPMs could be repeatedly utilized with no significant loss of adsorption efficiency.

  3. Removal of Chromium(VI) from Aqueous Solutions Using Fe₃O₄ Magnetic Polymer Microspheres Functionalized with Amino Groups.

    Science.gov (United States)

    Wang, Kai; Qiu, Guangming; Cao, Hongyu; Jin, Ruifa

    2015-12-03

    Magnetic polymer microspheres (MPMs) using glycidylmethacrylate (GMA) as a functional monomer were synthesized in the presence of Fe₃O₄ nanoparticles via dispersion polymerization. After polymerization, the magnetic polymer microbeads were modified with ethylenediamine (EDA). The obtained ethylenediamine-functionalized magnetic microspheres (EDA-MPMs) were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), vibrating-sample magnetometer (VSM) and Fourier transform infrared (FT-IR) spectroscopy. Then the EDA-MPMs were applied as adsorbents for the removal of Cr(VI) from aqueous solution. Langmuir equation was appropriate to describe the experimental data. The maximum adsorption capacities obtained from the Langmuir model were 236.9, 242.1 and 253.2 mg/g at 298, 308 and 318 K, respectively. The Cr(VI) adsorption equilibrium was established within 120 min and the adsorption kinetics was compatibly described by the pseudo-second order equation. The thermodynamic parameters (ΔG°, ΔH°, ΔS°) of the sorption process revealed that the adsorption was spontaneous and was an endothermic process. The regeneration study demonstrated that the EDA-MPMs could be repeatedly utilized with no significant loss of adsorption efficiency.

  4. Synthesis and Characterization of Molecular Imprinting Polymer Microspheres of Cinnamic Acid: Extraction of Cinnamic Acid from Spiked Blood Plasma

    Directory of Open Access Journals (Sweden)

    Alvin Leong Joke Chow

    2016-01-01

    Full Text Available The molecular imprinting technique is used to create the molecularly imprinted polymers (MIPs with higher binding capacity towards the template. In this research precipitation polymerization method with noncovalent approach was used to synthesize imprinted polymer microspheres. The polymerization reaction was conducted in a flask containing acetonitrile as a porogen, cinnamic acid as a template (T, acrylic acid (AA as a monomer, divinylbenzene (DVB as a cross-linker, and azobisisobutyronitrile as an initiator. The polymer particles were characterized by using SEM and FTIR. The rebinding efficiency was conducted by batch binding assay and the results were monitored by using HPLC. The batch binding results suggested MIP1 (T : AA : DVB, 1 : 6 : 20 molar ratio is most suitable composition for the rebinding of cinnamic acid. The highly selective polymer (MIP1 was used for the extraction of cinnamic acid from human plasma. The extraction efficiency of imprinted polymer of cinnamic acid from spiked plasma was above 75%.

  5. Efficient synthesis of narrowly dispersed hydrophilic and magnetic molecularly imprinted polymer microspheres with excellent molecular recognition ability in a real biological sample.

    Science.gov (United States)

    Zhao, Man; Zhang, Cong; Zhang, Ying; Guo, Xianzhi; Yan, Husheng; Zhang, Huiqi

    2014-02-28

    A facile and highly efficient approach to obtain narrowly dispersed hydrophilic and magnetic molecularly imprinted polymer microspheres with molecular recognition ability in a real biological sample as good as what they show in the organic solvent-based media is described for the first time.

  6. Microencapsulation of chemotherapeutics into monodisperse and tunable biodegradable polymers via electrified liquid jets: control of size, shape, and drug release.

    Science.gov (United States)

    Fattahi, Pouria; Borhan, Ali; Abidian, Mohammad Reza

    2013-09-06

    This paper describes microencapsulation of antitumor agent 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU, Carmustine) into biodegradable polymer poly(lactic-co-glycolic) acid (PLGA) using an electrojetting technique. The resulting BCNU-loaded PLGA microcapsules have significantly higher drug encapsulation efficiency, more tunable drug loading capacity, and (3) narrower size distribution than those generated using other encapsulation methods.

  7. Tetracycline-HCl-loaded poly(DL-lactide-co-glycolide) microspheres prepared by a spray drying technique: influence of gamma-irradiation on radical formation and polymer degradation.

    Science.gov (United States)

    Bittner, B; Mäder, K; Kroll, C; Borchert, H H; Kissel, T

    1999-05-01

    Tetracycline-HCl (TCH)-loaded microspheres were prepared from poly(lactide-co-glycolide) (PLGA) by spray drying. The drug was incorporated in the polymer matrix either in solid state or as w/o emulsion. The spin probe 4-hydroxy-2,2,6, 6-tetramethyl-piperidine-1-oxyl (TEMPOL) and the spin trap tert-butyl-phenyl-nitrone (PBN) were co-encapsulated into the TCH-loaded and placebo particles. We investigated the effects of gamma-irradiation on the formation of free radicals in polymer and drug and the mechanism of chain scission after sterilization. Gamma-Irradiation was performed at 26.9 and 54.9 kGy using a 60Co source. The microspheres were characterized especially with respect to the formation of radicals and in vitro polymer degradation. Electron paramagnetic resonance (EPR) spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), high-performance liquid chromatography (HPLC), gas chromatography-mass spectroscopy (GC-MS), and scanning electron microscopy (SEM) were used for characterization of the microspheres. Using EPR spectroscopy, we successfully detected gamma-irradiation induced free radicals within the TCH-loaded microspheres, while unloaded PLGA did not contain radicals under the same conditions. The relatively low glass transition temperature of the poly(dl-lactide-co-glycolide) (37-39 degrees C) seems to favor subsequent reactions of free radicals due to the high mobility of the polymeric chains. Because of the high melting point of TCH (214 degrees C), the radicals can only be stabilized in drug loaded microspheres. In order to determine the mechanism of polymer degradation after exposure to gamma-rays, the spin trap PBN and the spin probe TEMPOL were encapsulated in the microspheres. gamma-Irradiation of microspheres containing PBN resulted in the formation of a lipophilic spin adduct, indicating that a polymeric radical was generated by random chain scission. Polymer degradation by an unzipping mechanism would have

  8. PREPARATION AND CHARACTERIZATION OF AFFINITY POLYMER BASIC MICROSPHERES BY SOAP-FREE EMULSION POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Jing-ning Lv; Shi-jiang Fang; Lei Chen

    2009-01-01

    Poly(styrene-co-glycidyl methacrylate) latex microspheres with uniform size and high-density epoxy groups on the surface were prepared by soap-free emulsion polymerization with batch wise operation mode in the presence of 2,2'azobis(2-methylpropionamidine) dihydrochloride as an initiator.The kinetics of soap-free emulsion polymerization and the effects of polymerization factors were examined.In addition,the optimum polymerization conditions of poly(styrene-coglycidyl methacrylate) latex microspheres for immobilization of biomolecules were obtained.

  9. Preparation of Highly Thermally Conductive Polymer Composite at Low Filler Content via a Self-Assembly Process between Polystyrene Microspheres and Boron Nitride Nanosheets.

    Science.gov (United States)

    Wang, Xiongwei; Wu, Peiyi

    2017-06-14

    Rational distribution and orientation of boron nitride nanosheets (BNNSs) are very significant for a polymer/BNNS composite to obtain a high thermal conductivity at low filler content. In this paper, a high-performance thermal interface material based on exfoliated BNNSs and polystyrene (PS) microspheres was fabricated by latex blending and subsequent compression molding. In this case, BNNSs and PS microspheres first self-assembled to form the complex microspheres via strong electrostatic interactions between them. The as-prepared complex microspheres were further hot-pressed around the glass transition temperature, which brought the selective distribution of BNNSs at the interface of the deformed PS microspheres. As a consequence, a polymer composite with homogeneous dispersion and high in-plane orientation of BNNSs in PS matrix was obtained. Benefitted from this unique structure, the resultant composite exhibits a significant thermal conductivity enhancement of 8.0 W m(-1) K(-1) at a low filler content of 13.4 vol %. This facile method provides a new strategy to design and fabricate highly thermally conductive composites.

  10. Polymeric microspheres

    Science.gov (United States)

    Walt, David R.; Mandal, Tarun K.; Fleming, Michael S.

    2004-04-13

    The invention features core-shell microsphere compositions, hollow polymeric microspheres, and methods for making the microspheres. The microspheres are characterized as having a polymeric shell with consistent shell thickness.

  11. [A new embolic material: super absorbent polymer (SAP) microsphere and its embolic effects].

    Science.gov (United States)

    Jiaqi, Y; Hori, S; Minamitani, K; Hashimoto, T; Yoshimura, H; Nomura, N; Ishida, T; Fukuda, H; Tomoda, K; Nakamura, H

    1996-01-01

    SAP-Microsphere (sodium acrylic acid-vinyl alcohol copolymer) has the ability to absorb fluids within a few minutes and increase its diameter. Its diameter can also be calibrated. The diameters in ionic contrast material and human serum are 2.1 and 3.5 times larger, respectively, than the original size. It can pass through a microcatheter with an ionic contrast material, and swells at the occluding point into the desired size. It can be recognized under fluoroscopy due to its absorption of contrast material. A total of 10 rabbit kidney embolizations were done followed by resection in 1-14 weeks. Recanalization was absent in all cases. No adhesion to the perirenal tissue was found. Limited reactive change in endothelial cells was found at one week. No changes in the smooth muscle layer were found at any time during the study. Limited infiltration of neutrophil cells was found in perivascular tissue within a period of one week. SAP-Microspheres maintained their spherical shape during a 14-week period. Extensive fibrosis and calcification were found after 4 weeks. SAP-Microspheres are promising as an embolic agent to obtain satisfactory results of embolization therapy.

  12. Well-defined hydrophilic molecularly imprinted polymer microspheres for efficient molecular recognition in real biological samples by facile RAFT coupling chemistry.

    Science.gov (United States)

    Zhao, Man; Chen, Xiaojing; Zhang, Hongtao; Yan, Husheng; Zhang, Huiqi

    2014-05-12

    A facile and highly efficient new approach (namely RAFT coupling chemistry) to obtain well-defined hydrophilic molecularly imprinted polymer (MIP) microspheres with excellent specific recognition ability toward small organic analytes in the real, undiluted biological samples is described. It involves the first synthesis of "living" MIP microspheres with surface-bound vinyl and dithioester groups via RAFT precipitation polymerization (RAFTPP) and their subsequent grafting of hydrophilic polymer brushes by the simple coupling reaction of hydrophilic macro-RAFT agents (i.e., hydrophilic polymers with a dithioester end group) with vinyl groups on the "living" MIP particles in the presence of a free radical initiator. The successful grafting of hydrophilic polymer brushes onto the obtained MIP particles was confirmed by SEM, FT-IR, static contact angle and water dispersion studies, elemental analyses, and template binding experiments. Well-defined MIP particles with densely grafted hydrophilic polymer brushes (∼1.8 chains/nm(2)) of desired chemical structures and molecular weights were readily obtained, which showed significantly improved surface hydrophilicity and could thus function properly in real biological media. The origin of the high grafting densities of the polymer brushes was clarified and the general applicability of the strategy was demonstrated. In particular, the well-defined characteristics of the resulting hydrophilic MIP particles allowed the first systematic study on the effects of various structural parameters of the grafted hydrophilic polymer brushes on their water-compatibility, which is of great importance for rationally designing more advanced real biological sample-compatible MIPs.

  13. Multiple patterns of polymer gels in microspheres due to the interplay among phase separation, wetting, and gelation.

    Science.gov (United States)

    Yanagisawa, Miho; Nigorikawa, Shinpei; Sakaue, Takahiro; Fujiwara, Kei; Tokita, Masayuki

    2014-11-11

    We report the spontaneous patterning of polymer microgels by confining a polymer blend within microspheres. A poly(ethylene glycol) (PEG) and gelatin solution was confined inside water-in-oil (W/O) microdroplets coated with a layer of zwitterionic lipids: dioleoylphosphatidylethanolamine (PE) and dioleoylphosphatidylcholine (PC). The droplet confinement affected the kinetics of the phase separation, wetting, and gelation after a temperature quench, which determined the final microgel pattern. The gelatin-rich phase completely wetted to the PE membrane and formed a hollow microcapsule as a stable state in the PE droplets. Gelation during phase separation varied the relation between the droplet size and thickness of the capsule wall. In the case of the PC droplets, phase separation was completed only for the smaller droplets, wherein the microgel partially wetted the PC membrane and had a hemisphere shape. In addition, the temperature decrease below the gelation point increased the interfacial tension between the PEG/gelatin phases and triggered a dewetting transition. Interestingly, the accompanying shape deformation to minimize the interfacial area was only observed for the smaller PC droplets. The critical size decreased as the gelatin concentration increased, indicating the role of the gel elasticity as an inhibitor of the deformation. Furthermore, variously patterned microgels with spherically asymmetric shapes, such as discs and stars, were produced as kinetically trapped states by regulating the incubation time, polymer composition, and droplet size. These findings demonstrate a way to regulate the complex shapes of microgels using the interplay among phase separation, wetting, and gelation of confined polymer blends in microdroplets.

  14. Embedding of Hollow Polymer Microspheres with Hydrophilic Shell in Nafion Matrix as Proton and Water Micro-Reservoir

    Directory of Open Access Journals (Sweden)

    Zhaolin Liu

    2012-08-01

    Full Text Available Assimilating hydrophilic hollow polymer spheres (HPS into Nafion matrix by a loading of 0.5 wt % led to a restructured hydrophilic channel, composed of the pendant sulfonic acid groups (–SO3H and the imbedded hydrophilic hollow spheres. The tiny hydrophilic hollow chamber was critical to retaining moisture and facilitating proton transfer in the composite membranes. To obtain such a tiny cavity structure, the synthesis included selective generation of a hydrophilic polymer shell on silica microsphere template and the subsequent removal of the template by etching. The hydrophilic HPS (100–200 nm possessed two different spherical shells, the styrenic network with pendant sulfonic acid groups and with methacrylic acid groups, respectively. By behaving as microreservoirs of water, the hydrophilic HPS promoted the Grotthus mechanism and, hence, enhanced proton transport efficiency through the inter-sphere path. In addition, the HPS with the –SO3H borne shell played a more effective role than those with the –CO2H borne shell in augmenting proton transport, in particular under low humidity or at medium temperatures. Single H2-PEMFC test at 70 °C using dry H2/O2 further verified the impactful role of hydrophilic HPS in sustaining higher proton flux as compared to pristine Nafion membrane.

  15. Microspheres Sensor Based on Molecularly Imprinted Polymer Synthesized by Precipitation Polymerization

    Institute of Scientific and Technical Information of China (English)

    ZHANG,Zhao-Hui; LONG,Yu-Mei; LIU,Ying-Ju; YAO,Shou-Zhuo

    2003-01-01

    A new biomimetic bulk acoustic wave sensor based on molecularly imprinted microspheres(MIM) technique was described.The sensing materials were synthesized by precipitation polymerization.By using the Scatchard analysis,the equilibrium dissociation constant KD and the apparent maximum number Qmax of the binding sites were calculated to be 3.70 mmol·L-1 and 9.11 μmol·g-1,respectively.The sensor exhibited a sensitive response to detection limit of 2×10-9 mol·L-1.The recoveries of the sensor were 95.1%-105.4%.Studies presented in this paper show that the stability of this sensor is excellent.The sensor has been applied successfully to the determination of dipyridmaole in human urine.

  16. PLGA Microspheres Incorporated Gelatin Scaffold: Microspheres Modulate Scaffold Properties

    OpenAIRE

    Indranil Banerjee; Debasish Mishra; Maiti, Tapas K.

    2009-01-01

    Freeze drying is one of the popular methods of fabrication for poly(lactide-co-glycolide) (PLGA) microspheres incorporated polymer scaffolds. However, the consequence of microspheres incorporation on physical and biological properties of scaffold has not been studied yet. In this study, attempt has been made to characterize the effect of PLGA microsphere incorporation on the physical properties of freeze-dried gelatin scaffold and its influence on cytocompatibility. Scaffolds loaded with va...

  17. Synthesis of Monodisperse Silica Particles Grafted with Concentrated Ionic Liquid-Type Polymer Brushes by Surface-Initiated Atom Transfer Radical Polymerization for Use as a Solid State Polymer Electrolyte

    Directory of Open Access Journals (Sweden)

    Takashi Morinaga

    2016-04-01

    Full Text Available A polymerizable ionic liquid, N,N-diethyl-N-(2-methacryloylethyl-N-methylammonium bis(trifluoromethylsulfonylimide (DEMM-TFSI, was polymerized via copper-mediated atom transfer radical polymerization (ATRP. The polymerization proceeded in a living manner producing well-defined poly(DEMM-TFSI of target molecular weight up to about 400 K (including a polycation and an counter anion. The accurate molecular weight as determined by a GPC analysis combined with a light scattering measurement, and the molecular weight values obtained exhibited good agreement with the theoretical values calculated from the initial molar ratio of DEMM-TFSI and the monomer conversion. Surface-initiated ATRP on the surface of monodisperse silica particles (SiPs with various diameters was successfully performed, producing SiPs grafted with well-defined poly(DEMM-TFSI with a graft density as high as 0.15 chains/nm2. Since the composite film made from the silica-particle-decorated polymer brush and ionic liquid shows a relatively high ionic conductivity, we have evaluated the relationship between the grafted brush chain length and the ionic conductivity.

  18. Micron-sized Magnetic Polymer Microspheres for Adsorption and Separation of Cr(VI) from Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    王强; 官月平; 刘翔; 杨明珠; 任秀峰

    2012-01-01

    The magnetic poly-(methacrylate-divinyl benzene) microspheres with micron size were synthesized by modified suspension polymerization method. Adsorption of Cr(VI) from aqueous solution by magnetic poly-(MA-DVB) microspheres with surface amination was investigated. The adsorption processes were carried out under diversified conditions of pH value, adsorption time and temperature to evaluate the perlbrmance of the magnetic microspheres. The optimum pH value for Cr(VI) adsorption was found as 3. The adsorption capacity increased with adsorption time and attained an optimum at 60 rain. The adsorption processes for magnetic microspheres was endothermic reaction, and the adsorption capacity increased with increasing temperature.

  19. Characterization and Compatibility Studies of Different Rate Retardant Polymer Loaded Microspheres by Solvent Evaporation Technique: In Vitro-In Vivo Study of Vildagliptin as a Model Drug

    Directory of Open Access Journals (Sweden)

    Irin Dewan

    2015-01-01

    Full Text Available The present study has been performed to microencapsulate the antidiabetic drug of Vildagliptin to get sustained release of drug. The attempt of this study was to formulate and evaluate the Vildagliptin loaded microspheres by emulsion solvent evaporation technique using different polymers like Eudragit RL100, Eudragit RS100, Ethyl cellulose, and Methocel K100M. In vitro dissolution studies were carried out in 0.1 N HCl for 8 hours according to USP paddle method. The maximum and minimum drug release were observed as 92.5% and 68.5% from microspheres, respectively, after 8 hours. Release kinetics were studied in different mathematical release models to find out the linear relationship and release rate of drug. The SEM, DSC, and FTIR studies have been done to confirm good spheres and smooth surface as well as interaction along with drug and polymer. In this experiment, it is difficult to explain the exact mechanism of drug release. But the drug might be released by both diffusion and erosion as the correlation coefficient (R2 best fitted with Korsmeyer model and release exponent (n was 0.45–0.89. At last it can be concluded that all in vitro and in vivo experiments exhibited promising result to treat type II diabetes mellitus with Vildagliptin microspheres.

  20. Novel molecular imprinted polymers over magnetic mesoporous silica microspheres for selective and efficient determination of protocatechuic acid in Syzygium aromaticum.

    Science.gov (United States)

    Xie, Lianwu; Guo, Junfang; Zhang, Yuping; Hu, Yunchu; You, Qingping; Shi, Shuyun

    2015-07-01

    Improving sites accessibility can increase the binding efficiency of molecular imprinted polymers (MIPs). In this work, we firstly synthesized MIPs over magnetic mesoporous silica microspheres (Fe3O4@mSiO2@MIPs) for the selective recognition of protocatechuic acid (PCA). The resulting Fe3O4@mSiO2@MIPs were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FT-IR), thermo-gravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), and vibration sample magnetometer (VSM), and evaluated by adsorption isotherms/kinetics and competitive adsorption. The maximum adsorption capacity of PCA on Fe3O4@mSiO2@MIPs was 17.2mg/g (2.3 times that on Fe3O4@SiO2@MIPs). In addition, Fe3O4@mSiO2@MIPs showed a short equilibrium time (140min), rapid magnetic separation (5s) and high stability (retained 94.4% after six cycles). Subsequently, Fe3O4@mSiO2@MIPs were successfully applied for the selective and efficient determination of PCA (29.3μg/g) from Syzygium aromaticum. Conclusively, we combined three advantages into Fe3O4@mSiO2@MIPs, namely, Fe3O4 core for quick separation, mSiO2 layer for enough accessible sites, and surface imprinting MIPs for fast binding and excellent selectivity, to extract PCA from complex systems.

  1. Reactive carbon microspheres prepared by surface-grafting 4-(chloromethyl)phenyltrimethoxysilane for preparing molecularly imprinted polymer

    Science.gov (United States)

    Liu, Weifeng; Zhao, Huijun; Yang, Yongzhen; Liu, Xuguang; Xu, Bingshe

    2013-07-01

    Carbon microspheres (CMSs) were oxidized by a mixture of concentrated sulfuric and nitric acids, and modified by 4-(chloromethyl)phenyltrimethoxysilane to give reactive surface. Then, by adopting the surface molecular imprinting technique, dibenzothiophene (DBT) molecule-imprinted material MIP-DBT/CMSs was prepared with methacrylic acid as functional monomer and ethylene glycol dimethacrylate as crosslinking agent. The binding character of MIP-DBT/CMSs toward DBT was investigated with static method by gas chromatography, using fluorene and biphenyl as the reference substances which are similar to DBT in chemical structure to a certain extent. The effects of reaction time, temperature, and coupling agent concentration during silanization were investigated. The results show that the optimized conditions of silanization were 0.3 g oxidized-CMSs, 5% of CMTMS, 80 °C and 4 h. On the basis of silanized-CMSs, MIP-DBT/CMSs was synthesized. The adsorption results show that MIP-DBT/CMSs possessed strong adsorption ability for DBT. The maximal adsorption amount reached up 88.83 mg/g, in comparison with 44.51 mg/g of the non-imprinted polymer. In addition, MIP-DBT/CMSs exhibited a good selective adsorption capacity for DBT than fluorene (19.86 mg/g) and biphenyl (15.33 mg/g). The adsorption behavior followed the pseudo second order kinetic model. And the Freundlich isotherm was found to describe well the equilibrium adsorption data.

  2. Immobilisation and characterisation of biocatalytic co-factor recycling enzymes, glucose dehydrogenase and NADH oxidase, on aldehyde functional ReSyn™ polymer microspheres.

    Science.gov (United States)

    Twala, Busisiwe V; Sewell, B Trevor; Jordaan, Justin

    2012-05-10

    The use of enzymes in industrial applications is limited by their instability, cost and difficulty in their recovery and re-use. Immobilisation is a technique which has been shown to alleviate these limitations in biocatalysis. Here we describe the immobilisation of two biocatalytically relevant co-factor recycling enzymes, glucose dehydrogenase (GDH) and NADH oxidase (NOD) on aldehyde functional ReSyn™ polymer microspheres with varying functional group densities. The successful immobilisation of the enzymes on this new high capacity microsphere technology resulted in the maintenance of activity of ∼40% for GDH and a maximum of 15.4% for NOD. The microsphere variant with highest functional group density of ∼3500 μmol g⁻¹ displayed the highest specific activity for the immobilisation of both enzymes at 33.22 U mg⁻¹ and 6.75 U mg⁻¹ for GDH and NOD with respective loading capacities of 51% (0.51 mg mg⁻¹) and 129% (1.29 mg mg⁻¹). The immobilised GDH further displayed improved activity in the acidic pH range. Both enzymes displayed improved pH and thermal stability with the most pronounced thermal stability for GDH displayed on ReSyn™ A during temperature incubation at 65 °C with a 13.59 fold increase, and NOD with a 2.25-fold improvement at 45 °C on the same microsphere variant. An important finding is the suitability of the microspheres for stabilisation of the multimeric protein GDH.

  3. DNA Microspheres Coated with Bioavailable Polymer as an Efficient Gene Expression Agent in Yeasts

    Directory of Open Access Journals (Sweden)

    Irena Reytblat

    2016-01-01

    Full Text Available Gene delivery is one of the steps necessary for gene therapy and for genetic modification. However, delivering DNA into cells is challenging due to its negative charge that leads to repulsion by the negative cell membrane. In the current research, DNA spheres with a DNA encoding to a certain gene were coated with bioavailable polymers, polyethylene imine (PEI and polycaprolactone (PCL, in a short, one-step sonochemical reaction. The polymers were used in order to neutralize the negative charge of the DNA. Our study shows that the DNA nanospheres not only managed to penetrate the cell without causing it any damage, but also expressed the desired gene inside it.

  4. Preparation of molecularly imprinted microspheres by photo-grafting on supports modified with iniferter

    Institute of Scientific and Technical Information of China (English)

    RONG Fei; FENG Xiaogang; LI Ping; YUAN Chunwei; FU Degang

    2006-01-01

    Molecularly imprinted microspheres (MIMs) of D-mandelic acid were synthesized in this study. Chloromethylated polystyrene beads modified with iniferter were used as supports for photo-grafting of a molecularly imprinted polymer (MIP) layer. The polymers were characterized by FT-IR, elemental analysis and thermo-gravimetric analysis to testify the polymer formation and its thermal stability. Scanning electron micrographs (SEM) show that the MIP particles are mono-dispersed and well-spherical, with the average diameter of 4.38 μm and size distribution coefficient of 1.02. Furthermore, the MIMs were packed in a stainless steel column and evaluated as stationary phases in high performance liquid chromatography (HPLC). The prepared MIP exhibited a considerable capability of chiral separation between template and its enantiomer. Accordingly, this kind of MIP is likely to have wide applications in chemical sensing, chromatographic analysis and solid phase extraction.

  5. Selective removal of diclofenac from contaminated water using molecularly imprinted polymer microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Dai Chaomeng [State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Department of Environmental Technology, Chair of Environmental Process Engineering, Technical University of Berlin, Berlin (Germany); Geissen, Sven-Uwe, E-mail: sven.geissen@tu-berlin.de [Department of Environmental Technology, Chair of Environmental Process Engineering, Technical University of Berlin, Berlin (Germany); Zhang Yalei, E-mail: zhangyalei@tongji.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Zhang Yongjun [Department of Environmental Technology, Chair of Environmental Process Engineering, Technical University of Berlin, Berlin (Germany); Zhou Xuefei [State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China)

    2011-06-15

    A molecularly imprinted polymer (MIP) was synthesized by precipitation polymerization using diclofenac (DFC) as a template. Binding characteristics of the MIP were evaluated using equilibrium binding experiments. Compared to the non-imprinted polymer (NIP), the MIP showed an outstanding affinity towards DFC in an aqueous solution with a binding site capacity (Q{sub max}) of 324.8 mg/g and a dissociation constant (K{sub d}) of 3.99 mg/L. The feasibility of removing DFC from natural water by the MIP was demonstrated by using river water spiked with DFC. Effects of pH and humic acid on the selectivity and adsorption capacity of MIP were evaluated in detail. MIP had better selectivity and higher adsorption efficiency for DFC as compared to that of powdered activated carbon (PAC). In addition, MIP reusability was demonstrated for at least 12 repeated cycles without significant loss in performance, which is a definite advantage over single-use activated carbon. - Highlights: > A MIP was synthesized by precipitation polymerization using DFC as template. > The MIP had better selectivity and higher adsorption efficiency for DFC. > The MIP is an effective method for selective removal of DFC from complex water. > MIP reusability is a definite advantage over single-use activated carbon. - A diclofenac molecularly imprinted polymer synthesized by precipitation polymerization was used for the selective removal of diclofenac from contaminated water.

  6. Molecularly imprinted polymer microspheres prepared by Pickering emulsion polymerization for selective solid-phase extraction of eight bisphenols from human urine samples.

    Science.gov (United States)

    Yang, Jiajia; Li, Yun; Wang, Jincheng; Sun, Xiaoli; Cao, Rong; Sun, Hao; Huang, Chaonan; Chen, Jiping

    2015-05-01

    The bisphenol A (BPA) imprinted polymer microspheres were prepared by simple Pickering emulsion polymerization. Compared to traditional bulk polymerization, both high yields of polymer and good control of particle sizes were achieved. The characterization results of scanning electron microscopy and nitrogen adsorption-desorption measurements showed that the obtained molecularly imprinted polymer microsphere (MIPMS) particles possessed regular spherical shape, narrow diameter distribution (30-60 μm), a specific surface area (S(BET)) of 281.26 m(2) g(-1) and a total pore volume (V(t)) of 0.459 cm(3) g(-1). Good specific adsorption capacity for BPA was obtained in the sorption experiment and good class selectivity for BPA and its seven structural analogs (bisphenol F, bisphenol B, bisphenol E, bisphenol AF, bisphenol S, bisphenol AP and bisphenol Z) was demonstrated by the chromatographic evaluation experiment. The MIPMS as solid-phase extraction (SPE) packing material was then evaluated for extraction and clean-up of these bisphenols (BPs) from human urine samples. An accurate and sensitive analytical method based on the MIPMS-SPE coupled with HPLC-DAD has been successfully established for simultaneous determination of eight BPs from human urine samples with detection limits of 1.2-2.2 ng mL(-1). The recoveries of BPs for urine samples at two spiking levels (100 and 500 ng mL(-1) for each BP) were in the range of 81.3-106.7% with RSD values below 8.3%.

  7. Microstructuring of polymer films by femtosecond pulses through optically trapped polystyrene microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Astaf' ev, A A; Shakhov, A M; Sarkisov, Oleg M; Nadtochenko, V A

    2013-04-30

    We report the laser ablation of polymers by femtosecond (18 and 54 fs) pulses focused by 1 and 3.8 {mu}m diameter spherical microlenses, which are held by optical traps. It is shown that this technique allows one to produce surface structures with lateral dimensions up to {lambda}/6 (125 nm). It is found that the size of the structures depends on the diameter of the microlens; the highest spatial resolution is achieved by using 1 {mu}m diameter microlenses. (extreme light fields and their applications)

  8. Characterization and Compatibility Studies of Different Rate Retardant Polymer Loaded Microspheres by Solvent Evaporation Technique: In Vitro-In Vivo Study of Vildagliptin as a Model Drug

    OpenAIRE

    2015-01-01

    The present study has been performed to microencapsulate the antidiabetic drug of Vildagliptin to get sustained release of drug. The attempt of this study was to formulate and evaluate the Vildagliptin loaded microspheres by emulsion solvent evaporation technique using different polymers like Eudragit RL100, Eudragit RS100, Ethyl cellulose, and Methocel K100M. In vitro dissolution studies were carried out in 0.1 N HCl for 8 hours according to USP paddle method. The maximum and minimum drug re...

  9. Rational design on controlled release ion-exchange polymeric microspheres and polymer-lipid hybrid nanoparticles for the delivery of water-soluble drugs through a multidisciplinary approach

    Science.gov (United States)

    Li, Yongqiang

    Sulfopropyl dextran sulfate (SP-DS) microspheres and polymer-lipid hybrid nanoparticles (PLN) for the delivery of water-soluble anticancer drugs and P-glycoprotein inhibitors were developed by our group recently and demonstrated effectiveness in local chemotherapy. To optimize the delivery performance of these particulate systems, particularly PLN, an integrated multidisciplinary approach was developed, based on an in-depth understanding of drug-excipient interactions, internal structure, drug loading and release mechanisms, and application of advanced modeling/optimization techniques. An artificial neural networks (ANN) simulator capable of formulation optimization and drug release prediction was developed. In vitro drug release kinetics of SP-DS microspheres, with various drug loading and in different release media, were predicted by ANN. The effects of independent variables on drug release were evaluated. Good modeling performance suggested that ANN is a useful tool to predict drug release from ion-exchange microspheres. To further improve the performance of PLN, drug-polymer-lipid interactions were characterized theoretically and experimentally using verapamil hydrochloride (VRP) as a model drug and dextran sulfate sodium (DS) as a counter-ion polymer. VRP-DS complexation followed a stoichiometric rule and solid-state transformation of VRP were observed. Dodecanoic acid (DA) was identified as the lead lipid carrier material. Based upon the optimized drug-polymer-lipid interactions, PLN with high drug loading capacity (36%, w/w) and sustained release without initial burst release were achieved. VRP remained amorphous and was molecularly dispersed within PLN. H-bonding contributed to the miscibility between the VRP-DS complex and DA. Drug release from PLN was mainly controlled by diffusion and ion-exchange processes. Drug loading capacity and particle size of PLN depend on the formulation factors of the weight ratio of drug to lipid and concentrations of

  10. Selective removal of diclofenac from contaminated water using molecularly imprinted polymer microspheres.

    Science.gov (United States)

    Dai, Chao-Meng; Geissen, Sven-Uwe; Zhang, Ya-Lei; Zhang, Yong-Jun; Zhou, Xue-Fei

    2011-06-01

    A molecularly imprinted polymer (MIP) was synthesized by precipitation polymerization using diclofenac (DFC) as a template. Binding characteristics of the MIP were evaluated using equilibrium binding experiments. Compared to the non-imprinted polymer (NIP), the MIP showed an outstanding affinity towards DFC in an aqueous solution with a binding site capacity (Q(max)) of 324.8 mg/g and a dissociation constant (K(d)) of 3.99 mg/L. The feasibility of removing DFC from natural water by the MIP was demonstrated by using river water spiked with DFC. Effects of pH and humic acid on the selectivity and adsorption capacity of MIP were evaluated in detail. MIP had better selectivity and higher adsorption efficiency for DFC as compared to that of powdered activated carbon (PAC). In addition, MIP reusability was demonstrated for at least 12 repeated cycles without significant loss in performance, which is a definite advantage over single-use activated carbon. Copyright © 2011. Published by Elsevier Ltd.

  11. Molecularly imprinted polymer microspheres for solid-phase extraction of protocatechuic acid in Rhizoma homalomenae.

    Science.gov (United States)

    Chen, Fang-Fang; Wang, Guo-Ying; Shi, Yan-Ping

    2011-10-01

    Molecularly imprinted polymers (MIPs) had been prepared by precipitation polymerization method using acrylamide as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, acetonitrile as the porogen solvent and protocatechuic acid (PA), one of phenolic acids, as the template molecule. The MIPs were characterized by scanning electron microscopy and Fourier transform infrared, and their performance relative to non-imprinted polymers was assessed by equilibrium binding experiments. Six structurally similar phenolic acids, including p-hydroxybenzoic acid, gallic acid, salicylic acid, syringic acid, vanillic acid, ferulic acid were selected to assess the selectivity and recognition capability of the MIPs. The MIPs were applied to extract PA from the traditional Chinese medicines as a solid-phase extraction sorbent. The resultant cartridge showed that the MIPs have a good extraction performance and were able to selectively extract almost 82% of PA from the extract of Rhizoma homalomenae. Thus, the proposed molecularly imprinted-solid phase extraction-high performance liquid chromatography method can be successfully used to extract and analyse PA in traditional Chinese medicines.

  12. Interchain tube pressure effect in extensional flows of oligomer diluted nearly monodisperse polystyrene melts

    DEFF Research Database (Denmark)

    Rasmussen, Henrik K.; Huang, Qian

    2014-01-01

    We have derived a constitutive equation to explain the extensional dynamics of oligomer-diluted monodisperse polymers, if the length of the diluent has at least two Kuhn steps. These polymer systems have a flow dynamics which distinguish from pure monodisperse melts and solutions thereof, if the ...

  13. Safety and efficacy of doxorubicin-eluting superabsorbent polymer microspheres for the treatment of liver metastases from neuroendocrine tumours: preliminary results

    Science.gov (United States)

    Verslype, Chris; Laenen, Annouschka; Cornelissen, Sandra; Deroose, Christophe M.; Prenen, Hans; Vandecaveye, Vincent; Van Cutsem, Eric; Maleux, Geert

    2017-01-01

    Abstract Background The aim of the study was to retrospectively evaluate the symptom control, tumour response, and complication rate in patients with liver-predominant metastatic neuroendocrine tumours treated with transarterial chemoembolization using doxorubicin-eluting superabsorbent polymer (SAP) microspheres. Patients and methods Patients with neuroendocrine liver metastases who underwent hepatic transarterial chemoembolization using doxorubicin-eluting SAP-microspheres (50–100 μm Hepasphere/Quadrasphere Microsphere® particles, Merit Medical, South Jordan, Utah, USA) were included in this study. Pre-and post-procedure imaging studies were evaluated to assess short and intermediate-term tumour response using modified RECIST criteria. Symptom relief and procedure-related complications were evaluated. Results A total of 27 embolization procedures were performed on 17 patients. Twelve of 17 patients (70%) were symptomatic, including carcinoid syndrome (n = 8) and severe, uncontrollable hypoglycemia (n = 4). Eight of 12 patients (67%) had complete symptom relief, and the remaining 4 (33%) had partial relief. One patient developed ischemic cholecystitis (6%). No other hepatobiliary complications occurred. Short-term and intermediate-term imaging follow-up was available for 15/17 patients (88%) and 12/14 patients (86%) respectively. At short-term follow-up ( 3 months), partial response, stable disease and progressive disease were found respectively in 7 (58%), 3 (25%) and 2 (17%) patients. Conclusions Chemoembolization with doxorubicin-eluting SAP-microspheres is a safe and effective treatment option for neuroendocrine liver metastases and is associated with a low complication rate. In particular, no clinically evident liver necrosis or bile duct complications were encountered. PMID:28265235

  14. Mucoadhesive, triclosan-loaded polymer microspheres for application to the oral cavity: preparation and controlled release characteristics.

    Science.gov (United States)

    Kockisch, Sandra; Rees, Gareth D; Tsibouklis, John; Smart, John D

    2005-01-01

    The aim of this study was to develop mucoadhesive microspheres that can be utilised for the controlled release of triclosan in oral-care formulations, specifically dental pastes. Using a double-emulsion solvent evaporation technique, triclosan was incorporated into microspheres that were prepared from Gantreztrade mark MS-955, Carbopol 974P, polycarbophil or chitosan and the profiles for its release were established under simulated 'in use' conditions. Triclosan was rapidly released into a sodium lauryl sulphate containing buffer from all but the chitosan microspheres. The release of triclosan from microspheres suspended in a non-aqueous paste, was found to be sustained over considerable time-periods, which were influenced strongly by the nature of the polymeric carrier. For microspheres that were fabricated from Gantrez, Carbopol or polycarbophil, the release appeared to obey zero-order kinetics whereas in the case of chitosan-derived vehicles, the release profile fitted the Baker and Lonsdale model. The work has demonstrated that these polymeric microspheres, particularly those of chitosan, are promising candidates for the sustained release of triclosan in the oral cavity.

  15. Molecularly imprinted polymers on the surface of silica microspheres via sol-gel method for the selective extraction of streptomycin in aqueous samples.

    Science.gov (United States)

    Junjie, Li; Mei, Yang; Danqun, Huo; Changjun, Hou; Xianliang, Li; Guomin, Wang; Dan, Feng

    2013-03-01

    Streptomycin-imprinted silica microspheres were prepared by combining a surface molecular-imprinting technique with the sol-gel method. A mixture of tetrahydrofuran, ethanol, and water (6:1:1, v/v/v) was selected as dispersing solvent while 3-aminopropyltriethoxysilane and triethoxyphenylsilane acted as functional monomers, and tetraethyl orthosilicate as a cross-linker. Characterization of the molecularly imprinted polymers was conducted using scanning electron microscope and dynamic binding experiments. As compared to the nonimprinted polymers, the imprinted polymers exhibited a higher degree of saturated adsorption volume up to 26.3 mg/g, and better selectivity even in an aqueous solution with interfering compounds, including dihydrostreptomycin, neomycin, and tetracycline. The adsorption ability and selectivity were observed to be influenced by the mole ratio of 3-aminopropyltriethoxysilane and triethoxyphenylsilane. Feasibility of the polymers to be used for actual application was also evaluated with spiked samples, indicating great potential for large-scale applications. Moreover, the streptomycin-imprinted polymers can be repeatedly used for 12 cycles without losing original performance, which is beneficial for commercial use.

  16. Molecularly imprinted polymer microspheres prepared by Pickering emulsion polymerization for selective solid-phase extraction of eight bisphenols from human urine samples

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jiajia [Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Li, Yun; Wang, Jincheng [Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China); Sun, Xiaoli; Cao, Rong [Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Sun, Hao [Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China); Department of Chemistry, Liaoning University, Shenyang 110000 (China); Huang, Chaonan [Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Chen, Jiping, E-mail: chenjp@dicp.ac.cn [Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China)

    2015-05-04

    Highlights: • BPA imprinted polymer microspheres were prepared by Pickering emulsion polymerization. • Regular spherical shape and narrow diameter distribution. • Good specific adsorption capacity for BPA. • Good class-selectivity and clean-up efficiency for bisphenols in human urine under SPE mode. • Good recoveries and sensitivity for bisphenols using the MIPMS-SPE coupled with HPLC-DAD method. - Abstract: The bisphenol A (BPA) imprinted polymer microspheres were prepared by simple Pickering emulsion polymerization. Compared to traditional bulk polymerization, both high yields of polymer and good control of particle sizes were achieved. The characterization results of scanning electron microscopy and nitrogen adsorption–desorption measurements showed that the obtained molecularly imprinted polymer microsphere (MIPMS) particles possessed regular spherical shape, narrow diameter distribution (30–60 μm), a specific surface area (S{sub BET}) of 281.26 m{sup 2} g{sup −1} and a total pore volume (V{sub t}) of 0.459 cm{sup 3} g{sup −1}. Good specific adsorption capacity for BPA was obtained in the sorption experiment and good class selectivity for BPA and its seven structural analogs (bisphenol F, bisphenol B, bisphenol E, bisphenol AF, bisphenol S, bisphenol AP and bisphenol Z) was demonstrated by the chromatographic evaluation experiment. The MIPMS as solid-phase extraction (SPE) packing material was then evaluated for extraction and clean-up of these bisphenols (BPs) from human urine samples. An accurate and sensitive analytical method based on the MIPMS-SPE coupled with HPLC-DAD has been successfully established for simultaneous determination of eight BPs from human urine samples with detection limits of 1.2–2.2 ng mL{sup −1}. The recoveries of BPs for urine samples at two spiking levels (100 and 500 ng mL{sup −1} for each BP) were in the range of 81.3–106.7% with RSD values below 8.3%.

  17. 基于动态溶胀法制备中空聚合物微球%Synthesis of hollow polymer microspheres by dynamic swelling method

    Institute of Scientific and Technical Information of China (English)

    段涛; 张力; 聂冬梅; 杨波; 姬彦玲; 唐永建

    2012-01-01

    以表面带正电荷的μm级聚苯乙烯微球为种子,经过甲苯、二乙烯基苯溶胀,聚合与包覆等过程制备了直径约5μm的中空聚合物微球.研究了溶剂类型、溶剂用量对动态溶胀法制备的中空聚合物微球粒径、分布和结构的影响,讨论了中空聚合物微球的形成机理.结果表明:添加一定量甲苯、二甲苯等挥发性溶剂是动态溶胀法形成中空聚合物微球的前提;甲苯用量越多,溶胀后形成的中空结构越明显,孔径越大;选择低溶解性的二甲苯溶剂更有利于中空结构的形成.%Hollow polymer microspheres about 5 μm in diameter were synthesized by dynamic swelling method using micron-sized polystyrene spheres with positive charges on surfaces as seeds. The synthesis process included swelling by organic solvents such as toluene and divinylbenzene, polymerizing and coating. The influences of variety and dosage of organic solvents on diameter, size distribution and hole structure of hollow microspheres were investigated, and the formation mechanism of hollow microspheres was discussed. It is indicated that some volatile organic solvents, such as toluene and dimethylbenzene, are crucial to hollow structure formation. Experimental results show that, more toluene leads to larger hollow structure after swelling, and dimethylbenzene is good for hollow structure formation, owing to its low solubility.

  18. General and Robust Strategies for Multifunctional Organic-Inorganic Nanocompositesvia Direct Growth of Monodisperse Nanocrystals Intimately and Permanently Connected with Polymers

    Science.gov (United States)

    2016-04-21

    amphiphilic copolymer brushes: Poly( ethylene oxide )-graft-polystyrene. J. Polym. Sci. Part A: Polym. Chem. 44, 4361-4371 (2006). 2. Mora-Pale, M., Meli, L...results are summarized as follows. Recent research has witnessed tremendous advances in isotropic nanomaterials synthesis , which has provided access...nanocrystals of both fundamental and practical interest.(12, 13) Current emerging synthesis approaches, including template-assisted synthesis ,(14-16

  19. Hybrid polymer microspheres

    Science.gov (United States)

    Rembaum, A.

    1980-01-01

    Techniques have been successfully tested for bonding polymeric spheres, typically 0.1 micron in diameter, to spheres with diameter up to 100 microns. Hybrids are being developed as improved packing material for ion-exchange columns, filters, and separators.

  20. Microspheres prepared with different co-polymers of poly(lactic-glycolic acid) (PLGA) or with chitosan cause distinct effects on macrophages.

    Science.gov (United States)

    Bitencourt, Claudia da Silva; Silva, Letícia Bueno da; Pereira, Priscilla Aparecida Tartari; Gelfuso, Guilherme Martins; Faccioli, Lúcia Helena

    2015-12-01

    Microencapsulation of bioactive molecules for modulating the immune response during infectious or inflammatory events is a promising approach, since microspheres (MS) protect these labile biomolecules against fast degradation, prolong the delivery over longer periods of time and, in many situations, target their delivery to site of action, avoiding toxic side effects. Little is known, however, about the influence of different polymers used to prepare MS on macrophages. This paper aims to address this issue by evaluating in vitro cytotoxicity, phagocytosis profile and cytokines release from alveolar macrophages (J-774.1) treated with MS prepared with chitosan, and four different co-polymers of PLGA [poly (lactic-co-glycolic acid)]. The five MS prepared presented similar diameter and zeta potential each other. Chitosan-MS showed to be cytotoxic to J-774.1 cells, in contrast to PLGA-MS, which were all innocuous to this cell linage. PLGA 5000-MS was more efficiently phagocytized by macrophages compared to the other MS tested. PLGA 5000-MS and 5002-MS induced significant production of TNF-α, while 5000-MS, 5004-MS and 7502-MS decreased spontaneous IL-6 release. Nevertheless, only PLGA 5002-MS induced significant NFkB/SEAP activation. These findings together show that MS prepared with distinct PLGA co-polymers are differently recognized by macrophages, depending on proportion of lactic and glycolic acid in polymeric chain, and on molecular weight of the co-polymer used. Selection of the most adequate polymer to prepare a microparticulate drug delivery system to modulate immunologic system may take into account, therefore, which kind of immunomodulatory response is more adequate for the required treatment.

  1. Large scale manufacture of magnetic polymer particles using membranes and microfluidic devices

    Institute of Scientific and Technical Information of China (English)

    Qingchun; Yuan; Richard; A.; Williams

    2007-01-01

    Magnetic polymer particles have found applications in diverse areas such as biomedical treatments, diagnosis and separation technology. These applications require the particles to have controlled sizes and narrow size distributions to gain better control and reproducibility in use. This paper reviews recent developments in the preparation of magnetic polymer particles at nano- and micro-scales by encapsulating magnetic components with dissolved or in situ formed polymers. Particle manufacture using emulsification and embedment methods produces magnetic polymer particles at micro-scale dimensions. However, the production of particles in this range using conventional emulsification methods affords very limited control over particle sizes and polydispersity. We report on alternative routes using membrane and microfluidics emulsification techniques, which have a capability to produce monodisperse emulsions and polymer microspheres (with coefficients of variation of less than 10%) in the range from submicrometer to a few 100 μm. The performance of these manufacturing methods is assessed with a view to future applications.

  2. Preparation and surface modification of magnetic poly(methyl methacrylate) microspheres

    Institute of Scientific and Technical Information of China (English)

    YANG; Chengli; GUAN; Yueping; XING; Jianmin; LIU; Junguo

    2004-01-01

    [1]Kronick, P., Gilpin, R. W., Use of superparamagnetic particles for isolation of cells, J. Biochem. Biophy. Methods, 1986, 12: 73-80.[2]Li, X. H., Sun, Z. H., Synthesis of magnetic polymer microspheres and application for immobilization of proteinase of balillus sublitis, J. Appl. Polym. Sci., 1995, 58: 1991-1997.[3]Abudiab, T., Beitle, R. R., Preparation of magnetic immobilized metal affinity separation media and its use in the isolation of proteins, J. Chromatogr. A, 1998, 795:211-217.[4]Josephson, L., Magnetic particles for use in separations, US Patent, 4 672 040, 1987-06-09.[5]Cupta, P. K., Hung, C. T., Magnetically controlled targeted mi cro-carrier systems, Life Sci., 1989, 44: 175-186.[6]Kondo, A., Kamura, H., Higashitahi, K., Development and application of thermosenstive magnetic immunomicrospheres for antibody purification, Appl. Microbiol. Biotechnol., 1994, 41: 99-105.[7]Horák, D., Magnetic polyglycidylmethacrylate microspheres by dispersion polymerization, J. Polym. Sci., Part A: Polym. Chem.,2001, 39: 3707-3715.[8]Lee, J., Senna, M., Preparation of monodispersed polystyrene microspheres uniformly coated by magnetite via heterogeneous polymerization, Colloid Polym. Sci., 1995, 273: 76-82.[9]Liu, X. Q., Guan, Y. P., Xing, J. M. et al., Synthesis and properties of micron-size magnetic polymeric spheres with epoxy group,Chinese J. Chem. Eng., 2003, 11: 731-735.[10]Daniel, Magnetic polymer latex and preparation process, US Patent, 4 358 388, 1982-11-09.[11]Ugelstad, J., Ellingsen, T., Berge, A. et al., Magnetic Polymer Particles, PCT Int. Appl., WO Patent, 8 303 920, 1983-11-10.[12]Liu, X. Q., Liu, H. Z., Xing, J. M. et al., Preparation and characterization of superparamagnetic functional polymeric microspheres, China Particuology, 2003, 1: 76-79.[13]Wu, J. G., Modern Fourier Transform Infrared Spectroscopy Technology and Its Application (in Chinese), Beijing: Literature Press of Science and Technology

  3. Thermo- and pH-responsive polymer brushes-grafted gigaporous polystyrene microspheres as a high-speed protein chromatography matrix.

    Science.gov (United States)

    Qu, Jian-Bo; Xu, Yu-Liang; Liu, Jun-Yi; Zeng, Jing-Bin; Chen, Yan-Li; Zhou, Wei-Qing; Liu, Jian-Guo

    2016-04-08

    Dual thermo- and pH-responsive chromatography has been proposed using poly(N-isopropylacrylamide-co-butyl methacrylate-co-N,N-dimethylaminopropyl acrylamide) (P(NIPAM-co-BMA-co-DMAPAAM)) brushes grafted gigaporous polystyrene microspheres (GPM) as matrix. Atom transfer radical polymerization (ATRP) initiator was first coupled onto GPM through Friedel-Crafts acylation with 2-bromoisobutyryl bromide. The dual-responsive polymer brushes were then grafted onto GPM via surface-initiated ATRP. The surface composition, gigaporous structure, protein adsorption and dual-responsive chromatographic properties of the matrix (GPM-P(NIPAM-co-BMA-co-DMAPAAM) were characterized in detail. Results showed that GPM were successfully grafted with thermoresponsive cationic polymer brushes and that the gigaporous structure was well maintained. A column packed with GPM-P(NIPAM-co-BMA-co-DMAPAAM presented low backpressure, good permeability and appreciable thermo-responsibility. By changing pH of the mobile phase and temperature of the column in turn, the column can separate three model proteins at the mobile phase velocity up to 2528cmh(-1). A separation mechanism of this matrix was also proposed. All results indicate that the dual thermo- and pH-responsive chromatography matrix has great potentials in 'green' high-speed protein chromatography.

  4. Core-double-shell Fe3O4@carbon@poly(In(III)-carboxylate) microspheres: cycloaddition of CO2 and epoxides on coordination polymer shells constituted by imidazolium-derived Al(III)-Salen bifunctional catalysts.

    Science.gov (United States)

    An, Qiao; Li, Zifeng; Graff, Robert; Guo, Jia; Gao, Haifeng; Wang, Changchun

    2015-03-01

    A hydrid microsphere Fe3O4@carbon@poly(In(III)-carboxylate) consisting of a cluster of Fe3O4 nanoparticles as the core, a carbon layer as the inner shell and a porous In(III)-carboxylate coordination polymer as the outer shell was prepared and applied as a recyclable catalyst for the cycloaddition reaction of CO2 and epoxides. Construction of this hybrid microsphere was achieved in the two steps, including (1) the one-pot solvothermal synthesis of Fe3O4@C particles with the abundant carboxylic groups on the carbon surface and (2) the subsequent growth of the outer shell polymers based on the precipitation coordination polymerization. Imidazolium-substituted Salen ligands were synthesized and chelated with the In(III) ions using the terminal carboxylic groups. The coordination polymer shell was formed on the Fe3O4@C particles, and the structures including shell thickness, surface area and porosity could be varied by tuning the feeding ratios of the In(III) ions and the ligands. The optimal structure of the coordination polymers showed a shell thickness of ca. 45 nm with ∼5 nm of mesopore, 174.7 m(2)/g of surface area and 0.2175 cm(3)/g of pore volume. In light of gas uptake capability, catalytic activity and magnetic susceptibility, cycloaddition of CO2 with a series of epoxides were studied by using Al-complexed Fe3O4@C@In(III)-[IL-Salen] microspheres. The results validated that the self-supporting catalytic layer with high surface area was of remarkable advantages, which were attributed from great increment of effective active sites and combination of nucleophilic/electrophilic synergistic property and CO2 uptake capability. Therefore, these hybrid microspheres provided excellent catalytic activity, prominent selectivity to cyclic carbonates and outstanding recyclability with the assistance of an applied magnetic field.

  5. Optical properties of metallo-dielectric microspheres in opal structures

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Y; Whitehouse, C; Li, Jensen; Tam, Wing Yim; Chan, C T; Sheng Ping [Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)

    2003-09-03

    We report the fabrication of opal structure using metallo-dielectric silica microspheres. Mono-dispersed silica microspheres were coated with silver using an electrode-less wet-plating technique. Thin slabs of opal were obtained by assembling the silver-coated microspheres between two glass plates using a forced-packing method. The optical properties of the resulting opal structure were studied in the infrared range. Good agreement is obtained with the predictions of a multiple scattering approach, provided that the silver layer is modelled as a silver composite.

  6. Polyacrolein microspheres

    Science.gov (United States)

    Rembaum, Alan (Inventor)

    1987-01-01

    Microspheres of acrolein homopolymers and copolymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

  7. Enhancement of cell-based therapeutic angiogenesis using a novel type of injectable scaffolds of hydroxyapatite-polymer nanocomposite microspheres.

    Directory of Open Access Journals (Sweden)

    Yohei Mima

    Full Text Available BACKGROUND: Clinical trials demonstrate the effectiveness of cell-based therapeutic angiogenesis in patients with severe ischemic diseases; however, their success remains limited. Maintaining transplanted cells in place are expected to augment the cell-based therapeutic angiogenesis. We have reported that nano-hydroxyapatite (HAp coating on medical devices shows marked cell adhesiveness. Using this nanotechnology, HAp-coated poly(l-lactic acid (PLLA microspheres, named nano-scaffold (NS, were generated as a non-biological, biodegradable and injectable cell scaffold. We investigate the effectiveness of NS on cell-based therapeutic angiogenesis. METHODS AND RESULTS: Bone marrow mononuclear cells (BMNC and NS or control PLLA microspheres (LA were intramuscularly co-implanted into mice ischemic hindlimbs. When BMNC derived from enhanced green fluorescent protein (EGFP-transgenic mice were injected into ischemic muscle, the muscle GFP level in NS+BMNC group was approximate fivefold higher than that in BMNC or LA+BMNC groups seven days after operation. Kaplan-Meier analysis demonstrated that NS+BMNC markedly prevented hindlimb necrosis (P<0.05 vs. BMNC or LA+BMNC. NS+BMNC revealed much higher induction of angiogenesis in ischemic tissues and collateral blood flow confirmed by three-dimensional computed tomography angiography than those of BMNC or LA+BMNC groups. NS-enhanced therapeutic angiogenesis and arteriogenesis showed good correlations with increased intramuscular levels of vascular endothelial growth factor and fibroblast growth factor-2. NS co-implantation also prevented apoptotic cell death of transplanted cells, resulting in prolonged cell retention. CONCLUSION: A novel and feasible injectable cell scaffold potentiates cell-based therapeutic angiogenesis, which could be extremely useful for the treatment of severe ischemic disorders.

  8. A facile method to produce highly monodispersed nanospheres of cystine aggregates

    Science.gov (United States)

    Han, Hongliang; Wang, Chungang; Ma, Zhanfang; Su, Zhongmin

    2006-10-01

    Multiple shapes of nano- and micro-structured cystine aggregates, including spheres, rods, spindles, dendrites, and multipods, were easily synthesized just by adjusting the concentrations and pH values of L-Cysteine solutions under ultrasonic irritation. Importantly, highly monodispersed nanospheres of cystine aggregates 225 nm in diameter without any other shapes were easily obtained for the system of 0.1 M L-Cysteine with pH 8. This will provide a very simple and effective approach to produce monodispersed cystine microspheres, which could promote new possibilities for future applications in biosensor, drug delivery, medicine, and the production of nanomaterials.

  9. A facile method to produce highly monodispersed nanospheres of cystine aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Han Hongliang; Wang Chungang; Ma Zhanfang; Su Zhongmin [Chemistry Department, Northeast Normal University, Changchun 130024 (China)

    2006-10-28

    Multiple shapes of nano- and micro-structured cystine aggregates, including spheres, rods, spindles, dendrites, and multipods, were easily synthesized just by adjusting the concentrations and pH values of L-Cysteine solutions under ultrasonic irritation. Importantly, highly monodispersed nanospheres of cystine aggregates 225 nm in diameter without any other shapes were easily obtained for the system of 0.1 M L-Cysteine with pH 8. This will provide a very simple and effective approach to produce monodispersed cystine microspheres, which could promote new possibilities for future applications in biosensor, drug delivery, medicine, and the production of nanomaterials.

  10. Monodisperse magnetite (Fe3O4) nanoparticles modified with water soluble polymers for the diagnosis of breast cancer by MRI method

    Science.gov (United States)

    Rezayan, Ali Hossein; Mousavi, Majid; Kheirjou, Somayyeh; Amoabediny, Ghasem; Ardestani, Mehdi Shafiee; Mohammadnejad, Javad

    2016-12-01

    In this study, magnetic nanoparticles (MNPs) were synthesized via co-precipitation method. To enhance the biocompatibility and colloidal stability of the synthesized nanoparticles, they were modified with carboxyl functionalized PEG via dopamine (DPA) linker. Both modified and unmodified Fe3O4 nanoparticles exhibited super paramagnetic behavior (particle size below 20 nm). The saturation magnetization (Ms) of PEGdiacid-modified Fe3O4 was 45 emu/g, which was less than the unmodified Fe3O4 nanoparticles (70 emu/g). This difference indicated that PEGdiacid polymer was immobilized on the surface of Fe3O4 nanoparticles successfully. To evaluate the efficiency of the resulting nanoparticles as contrast agents for magnetic resonance imaging (MRI), different concentration of MNPs and different value of echo time TE were investigated. The results showed that by increasing the concentration of the nanoparticles, transverse relaxation time (T2) decreased, which subsequently resulted in MR signal enhancement. T2-weighted MR images of the different concentration of MNPs in different value of echo time TE indicated that MR signal intensity increased with increase in TE value up to 66 and then remained constant. The cytotoxicity effect of the modified and unmodified nanoparticles was evaluated in three different concentrations (12, 60 and 312 mg l-1) on MDA-MB-231 cancer cells for 24 and 48 h. In both tested time (24 and 48 h) for all three samples, the modified nanoparticles had long life time than unmodified nanoparticles. Cellular uptake of modified MNPs was 80% and reduced to 9% by the unmodified MNPs.

  11. Simultaneous extraction and separation of flavonols and flavones from Chamaecyparis obtusa by multi-phase extraction using an ionic liquid-modified microsphere polymer.

    Science.gov (United States)

    Tian, Minglei; Bi, Wentao; Row, Kyung Ho

    2012-01-01

    Flavonols and flavones, especially quercitrin, myricetin and amentoflavone, are the main anti-bacterial and anti-cancer compounds in Chamaecyparis obtuse. Multi-phase extraction is a new method that can extract and separate target compounds simultaneously. An amino ionic liquid immobilised microsphere polymer was used as a multi-phase extraction sorbent to extract and separate quercitrin, myricetin and amentoflavone from Chamaecyparis obtusa. The sorbent and Chamaecyparis obtusa powder were packed into a single cartridge. Using a fixed volume of methanol with five repetitions, the target compounds were extracted from the powder to the sorbent. The sorbent was then washed with n-hexane to remove any interfering species and the target compounds were eluted sequentially using water, methanol and methanol containing 1% acetic acid (vol.). Under the optimised conditions, 0.45 mg/g of quercitrin, 0.18 mg/g of myricetin and 0.12 mg/g of amentoflavone from 2.0 g of powder were obtained by multi-phase extraction using 0.3 g of sorbent. The method described has a low deviation error, requires a small amount of solvent and is highly selective and reproducible. Copyright © 2012 John Wiley & Sons, Ltd.

  12. Thermo-responsive polymer tethered metal-organic framework core-shell magnetic microspheres for magnetic solid-phase extraction of alkylphenols from environmental water samples.

    Science.gov (United States)

    Jia, Yuqian; Su, Hao; Wong, Y-L Elaine; Chen, Xiangfeng; Dominic Chan, T-W

    2016-07-22

    In this work, the thermo-responsive polymer PNIPAM tethered to Fe3O4@SiO2@MOF core-shell magnetic microspheres was first synthesized by a surface-selective post-synthetic strategy and underwent highly efficient magnetic solid-phase extraction (MSPE) of alkylphenols from aqueous samples. Alkylphenols, including 4-tert-octylphenol (OP) and 4-n-nonylphenol (NP), were selected as target compounds. The sample quantification was carried out using LC-MS/MS in multiple reaction monitor (MRM) mode. Under optimal working conditions, the developed method showed good linearity in the range of 5-1000ngL(-1), a low limit of detection (1.5ngL(-1)), and good repeatability (relative standard deviation, <8%, n=5) for NP and OP. Owning to the hydrophilic/hydrophobic switchable properties of the nanocomposite, high recoveries (78.7-104.3%) of alkylphenols were obtained under different extraction conditions. The levels of OP and NP in environmental samples collected from local river, lake and pond waters were analyzed using the developed method. It was believed that the synthesized material with the thermo-responsive coating, large surface areas and magnetic properties should have great potential in the extraction and removal of alkylphenols from environmental samples.

  13. Preparation of large monodisperse vesicles.

    Directory of Open Access Journals (Sweden)

    Ting F Zhu

    Full Text Available Preparation of monodisperse vesicles is important both for research purposes and for practical applications. While the extrusion of vesicles through small pores (approximately 100 nm in diameter results in relatively uniform populations of vesicles, extrusion to larger sizes results in very heterogeneous populations of vesicles. Here we report a simple method for preparing large monodisperse multilamellar vesicles through a combination of extrusion and large-pore dialysis. For example, extrusion of polydisperse vesicles through 5-microm-diameter pores eliminates vesicles larger than 5 microm in diameter. Dialysis of extruded vesicles against 3-microm-pore-size polycarbonate membranes eliminates vesicles smaller than 3 microm in diameter, leaving behind a population of monodisperse vesicles with a mean diameter of approximately 4 microm. The simplicity of this method makes it an effective tool for laboratory vesicle preparation with potential applications in preparing large monodisperse liposomes for drug delivery.

  14. Labelling of silica microspheres with fluorescent lanthanide-doped LaF{sub 3} nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yong [Division of Bioengineering, Faculty of Engineering, National University of Singapore, 117576, Singapore (Singapore); Lu Meihua [Division of Bioengineering, Faculty of Engineering, National University of Singapore, 117576, Singapore (Singapore)

    2007-07-11

    Fluorescent microspheres have been demonstrated to be useful in a variety of biological applications. Fluorescent silica or polymer microspheres have been produced by incorporation of chromophores into the microspheres, which usually produces microspheres with nonuniform sizes and reduced fluorescence. Here we present a simple and straightforward method to produce silica microspheres with fluorescent lanthanide-doped LaF{sub 3} nanocrystals grown on the surface. LaF{sub 3} nanocrystals are in situ grown on silica microspheres of different sizes to form a raspberry-like structure. The microspheres exhibit strong fluorescence and the colour could be altered by changing the lanthanide ions doped in LaF{sub 3} nanocrystals.

  15. Remote activation of a microactuator using a photo-responsive nanoparticle-polymer composite

    Science.gov (United States)

    Zeberoff, Anthony

    Stimulus response materials are a class of novel materials that are currently being explored in various technologies, including biomedical devices and components, food packaging, fabrics, energy harvesting and conversion, and other elementary components such as sensors and actuators. Hybrid organic-inorganic materials such as nanoparticle-polymer composites are attractive candidates as their properties can be significantly tuned for particular applications where selectivity and localized responses are critical factors. In this work we developed and optimized a photo-responsive microactuator that can operate selectively to a specific wavelength of light. The photo-responsive microactuator is comprised of monodispersed microspheres that contain gold nanoparticles. Upon irradiation, these microspheres transduce optical energy to thermal energy, driving a localized phase change in the matrix in which they are embedded. Our remotely powered microactuator can be further realized in applications where decoupling the physical connection of the energy/control source from the actuating component is necessary.

  16. Molecularly imprinted polymer grafted on polysaccharide microsphere surface by the sol-gel process for protein recognition.

    Science.gov (United States)

    Li, Feng; Li, Jing; Zhang, Shusheng

    2008-02-15

    An interfacial organic-inorganic hybridization concept was applied to the preparation of a new spherical imprinted material for protein recognition. The functional biopolymer chitosan (CS), shaped as microsphere and high-density cross-linked, constituted of the polysaccharide core for surface imprinting. After the model template protein, bovine serum albumin, was covalently immobilized by forming imine bonds with the functional amine groups of CS, two kinds of organic siloxane (3-aminopropyltrimethoxysiloxane: APTMS, and tetraethoxysiloxane: TEOS) assembled and polymerized on the polysaccharide-protein surface via sol-gel process in aqueous solution at room temperature. After template removal, the protein-imprinted sol-gel surface exhibited a prevalent preference for the template protein in adsorption experiments, as compared with four contrastive proteins. Bioinformatics methods were also employed to investigate the imprinting process and the recognition effect. The influence of siloxane type, pH, siloxane/water ratio on template removal and recognition selectivity was assessed. Under optimized imprinting conditions, a large quantity of well-distributed pores was observed on the immobilized-template imprinted surface. The surface-imprinted adsorbent offered a fast kinetics for template re-adsorption and could be reused. Compared with the imprinted material prepared with free-template, material prepared with immobilized-template possessed higher adsorption capacity towards template protein. Easy preparation of the described imprinted material, high affinity and good reusability make this approach attractive and broadly applicable in biotechnology for down-stream processing and biosensor.

  17. Microspheres prepared with biodegradable PHBV and PLA polymers as prolonged-release system for ibuprofen: in vitro drug release and in vivo evaluation

    Directory of Open Access Journals (Sweden)

    Giovana Carolina Bazzo

    2012-12-01

    Full Text Available In this study, poly(hydroxybutyrate-co-hydroxyvalerate (PHBV and poly(l-lactide (PLA microspheres containing ibuprofen were prepared with the aim of prolonging the drug release. The oil-in-water (O/W emulsion solvent evaporation technique was used, varying the polymer ratio. All formulations provided spherical particles with drug crystals on the surface and a porous and rough polymeric matrix when PHBV was used and smooth external surface when prepared with PLA. The in vitro dissolution profiles show that the formulation containing PHBV/PLA at the proportion of 30/70 presented the best results in terms of prolonging the ibuprofen release. The analysis of the concentration of ibuprofen in the blood of rats showed that maximum levels were achieved at between one and two hours after administration of the immediate-release form (pure drug, while the prolonged microspheres led to a small amount of the drug being released within the first two hours and reached the maximum level after six hours of administration. It was concluded that it is possible to prolong the release of ibuprofen through its incorporation into PHBV/PLA microspheres.No presente estudo foram preparadas microesferas de poli(hidroxibutirato-co-hidroxivalerato (PHBV e poli(ácido láctico (PLA com o objetivo de prolongar a liberação do ibuprofeno, utilizado como fármaco modelo. Empregou-se o método de emulsificação e evaporação do solvente óleo em água (O/A, variando-se a proporção entre os polímeros. Todas as formulações originaram partículas esféricas com cristais de fármaco aderidos à superfície externa. As microesferas apresentaram superfície rugosa e porosa, quando o PHBV foi utilizado, e superfície externa lisa, quando preparadas com o PLA. Os perfis de dissolução in vitro evidenciaram que a formulação que continha PHBV/PLA na proporção de 30/70 apresentou melhores resultados para prolongar a liberação do ibuprofeno. Através da análise da concentra

  18. Photocatalytic reduction of CO{sub 2} into methanol and ethanol over conducting polymers modified Bi{sub 2}WO{sub 6} microspheres under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Weili, E-mail: wldai81@126.com; Xu, Hai; Yu, Juanjuan; Hu, Xu; Luo, Xubiao, E-mail: luoxubiao@126.com; Tu, Xinman; Yang, Lixia

    2015-11-30

    Graphical abstract: - Highlights: • Conducting polymers modified Bi{sub 2}WO{sub 6} HHMS (CP/Bi{sub 2}WO{sub 6}) was successfully synthesized. • The introduction of CP decreases the recombination of photogenerated e{sup –}–h{sup +} pairs. • The PTh/Bi{sub 2}WO{sub 6} exhibites good stability and recyclability for CO{sub 2} photoreduction. • The possible photocatalytic mechanism was discussed and proposed. - Abstract: Bi{sub 2}WO{sub 6} hierarchical hollow microspheres (HHMS) modified with different conducting polymers (polyaniline, polypyrrole, and polythiophene) were successfully synthesized by ‘in situ’ deposition oxidative polymerization method, and evaluated as photocatalysts for the photocatalytic reduction of CO{sub 2} with H{sub 2}O to methanol and ethanol. It was found that the introduction of conducting polymers obviously decreased the recombination of photogenerated electron–hole pairs, thus promoting the photocatalytic activity of Bi{sub 2}WO{sub 6}. Among the as-fabricated photocatalysts, polythiophene modified Bi{sub 2}WO{sub 6} (PTh/Bi{sub 2}WO{sub 6}) exhibited the best photoelectronic and photocatalytic performance, due to the narrow band gap and good charge mobility of polythiophene. The results demonstrate that the methanol and ethanol yield over PTh/Bi{sub 2}WO{sub 6} was 56.5 and 20.5 μmol g{sub cat}{sup −1} in 4 h, respectively. The total yield of hydrocarbons is 2.8 times higher than that over pure Bi{sub 2}WO{sub 6}. It is noted that the catalyst exhibits good recyclability and stability. After five consecutive runs, the PTh/Bi{sub 2}WO{sub 6} catalyst shows no significant loss of photocatalytic activity. The possible photocatalytic mechanism was proposed which is beneficial for further improving the activity of photocatalysts. The approach described in this study provides a simple and reliable strategy for the rational design of efficient visible light-driven photocatalysts for photoreduction of CO{sub 2} to hydrocarbons.

  19. Preparation and Sustained Release of Theophylline β-Cyclodextrin Polymer Microspheres Inclusion Compound%茶碱β-环糊精聚合物微球的制备与缓释性能

    Institute of Scientific and Technical Information of China (English)

    杨黎燕; 杨威; 尤静; 张静姝

    2011-01-01

    Objective:Theophylline β-cyclodextrin polymer(β-CDP) microspheres inclusion compound was prepared withβ-cyclodextrin as material by coprecipitation method.Method:The preparation process was optimized through the L9 ( 34 ) orthogonal experimental design and theophylline release from theophylline β-cyclodextrin polymer microspheres was evaluated in vitro.Theophylline β-cyclodextrin polymer microspheres was characterized by laser particle analyzer, FT-IR spectroscopy, thermogravimetric analysis (TGA) and X-ray diffraction (XRD).Result:The optimal procedure was β-CDP microspheres 1 g, theophylline 0.02 g, water 30 mL, time 3 h, and inclusion temperature 60 ℃.Average diameter of optimized products was 162.35 μm and the drug loading and drug encapsulation efficiency were 1.79% and 89.50% respectively.The drug release profile could be described by first-order release equation and Korsmeyer-Peppas equation.Conclusion:The sustained release microspheres had determinate effects be observed and this preparation method was reasonable and feasible.%目的:以β-环糊精为原料,采用共沉淀法制备茶碱β环糊精聚合物(CDP)微球.方法:通过L9(3(4))正交试验设计对制备工艺进行了优化,并采用体外动态释药法评价其释药特征.分别用激光粒度分布仪、红外光谱仪、综合热分析仪、X射线衍射仪对茶碱β-CDP载药微球进行表征.结果:最佳工艺条件是β-CDP微球1g、茶碱0.02 g,蒸馏水30 mL、反应时间3h,温度60℃.合成的载药微球形态良好,平均粒径为162.35μm,载药量为1.79%,包封率为89.50%.茶碱β-CDP微球体外释药规律符合一级释放方程和Korsmeyer-Peppas模型方程.结论:茶碱载药微球具有一定缓释效果,其制备方法合理可行.

  20. Removal of radioactive contaminants by polymeric microspheres.

    Science.gov (United States)

    Osmanlioglu, Ahmet Erdal

    2016-11-01

    Radionuclide removal from radioactive liquid waste by adsorption on polymeric microspheres is the latest application of polymers in waste management. Polymeric microspheres have significant immobilization capacity for ionic substances. A laboratory study was carried out by using poly(N-isopropylacrylamide) for encapsulation of radionuclide in the liquid radioactive waste. There are numbers of advantages to use an encapsulation technology in radioactive waste management. Results show that polymerization step of radionuclide increases integrity of solidified waste form. Test results showed that adding the appropriate polymer into the liquid waste at an appropriate pH and temperature level, radionuclide was encapsulated into polymer. This technology may provide barriers between hazardous radioactive ions and the environment. By this method, solidification techniques became easier and safer in nuclear waste management. By using polymer microspheres as dust form, contamination risks were decreased in the nuclear industry and radioactive waste operations.

  1. 共轴微反应器制备单分散聚N-异丙基丙烯酰胺/蒙脱石纳米复合微凝胶%Preparation of monodisperse poly(N-isopropylacrylamide)/clay nanocomposite hydrogel microspheres using coaxial microfluidic device

    Institute of Scientific and Technical Information of China (English)

    纪磊鹏; 张青红; 李耀刚; 王宏志

    2011-01-01

    A monodisperse nanocomposite poly ( N-isopropylacrylamide)/clay ( PNIPAm/Clay) microspheres is synthesized with coaxial microfluidic device using clay as cross-linker. The disperse phase contains the monomer ( N-isopropylacrylamide) ( NIPAm) , the initiator ( potassium peroxydisulfate) ( KPS ) , the cross-linker ( clay) and deionized water. The immiscible continuous phase is composed of soya-bean oil and the catalyst ( tetramethyl ethylene diamine) ( TEMED) . The monomer, NIPAm , has three distinctive absorbance peaks at 917 ,965 , 992 cm -1 ,indicating the vibration of the monomer's C -C double bond. However, these characteristic peaks disappear in the FF-IR spectra of PNIPAm/Clay and the Si-O characteristic peaks of clay,l 000 cm -1 ,appears in the FT-IR spectra of PNIPAm/Clay.The effects of changing tips, the flow rate of continuous phase and the content of the surfactant on the size of the microgels are studied. The results show that the microgels from 300 μn to 450 μm can be synthesized by changing the Lips of the dispersed phase injection tube;The size of the microgels between 315 and 435 μm with dispersion coefflcient below 5% can be adjusted by changing the flow rate of continuous phase;The diameter of the microgels decreases when the content of the surfactant( polyglycerol polyricinoleate) ( PGPR) in the continuous phase increases.%以蒙脱石(Clay)为交联剂,采用含有N,N,N'N'-四甲基乙二胺(TEMED)的豆油溶液为连续相,含有单体N-异丙基丙烯酞胺(NIPAm)、引发剂过硫酸钾(KPS)和分散有蒙脱石的水溶液为分散相,在共轴毛细管微反应器中制备了单分散聚N-异丙基丙烯酞胺/蒙脱石(PNIPAm/Clay)复合微凝胶.红外光谱分析表明:单体的C=C双键的红外特征峰917、965cm-1和992 cm-1在聚合后的微凝胶红外谱图中消失,而Clay的Si-O键特征峰1000 cm-1则出现在微凝胶的红外谱图中.研究了不同内径的管头、分散相的流速和表面活性剂的浓度对微

  2. Fluorescent microspheres

    Science.gov (United States)

    Rembaum, A.

    1978-01-01

    Latex particles with attached antibodies have potential biochemical and environmental applications. Human red blood cells and lymphocytes have been labeled with fluorescent microspheres by either direct or indirect immunological technique. Immunolatex spheres can also be used for detecting and localizing specific cell surface receptors. Hormones and toxins may also be bondable.

  3. Preparation of biodegradable microspheres and matrix devices containing naltrexone

    OpenAIRE

    DINARVAND, RASSOUL; Moghadam, Shadi H.; Mohammadyari-Fard, Leyla; Atyabi, Fatemeh

    2003-01-01

    In this study, the use of biodegradable polymers for microencapsulation of naltrexone using solvent evaporation technique is investigated. The use of naltrexone microspheres for the preparation of matrix devices is also studied. For this purpose, poly(L-lactide) (PLA) microspheres containing naltrexone prepared by solvent evaporation technique were compressed at temperatures above the Tg of the polymer. The effect of different process parameters, such as drug/polymer ratio and stirring rate d...

  4. Preparation of microstructured hydroxyapatite microspheres using oil in water emulsions

    Indian Academy of Sciences (India)

    T S Pradeesh; M C Sunny; H K Varma; P Ramesh

    2005-08-01

    Hydroxyapatite (HAP) microspheres with peculiar spheres-in-sphere morphology were prepared by using oil-in-water emulsions and solvent evaporation technique. Ethylene vinyl acetate co-polymer (EVA) was used as the binder material. Preparation of HAP/EVA microspheres was followed by the thermal debinding and sintering at 1150°C for 3 h to obtain HAP microspheres. Each microsphere of 100–1000 m was in turn composed of spherical hydroxyapatite granules of 2–15 m size which were obtained by spray drying the precipitated HAP. The parameters such as percentage of initial HAP loading, type of stabilizer, concentration of stabilizer, stirring speed and temperature of microsphere preparation were varied to study their effect on the particle size and geometry of the microspheres obtained. It was observed that these parameters do have an effect on the size and shape of the microspheres obtained, which in turn will affect the sintered HAP microstructure. Of the three stabilizers used viz. polyoxyethylene(20) sorbitan monopalmitate (Tween-40), sodium laurate and polyvinyl alcohol (PVA), only PVA with a concentration not less than 0.1 wt% showed controlled stabilization of HAP granules resulting in spherical microspheres of required size. Morphologically better spherical microspheres were obtained at 20°C. Increasing the stirring speed produced smaller microspheres. Smaller microspheres having size < 50 m were obtained at a stirring speed of 1500 ± 50 rpm. A gradual decrease in pore size was observed in the sintered microspheres with increase in HAP loading.

  5. PLGA and PHBV Microsphere Formulations and Solid-State Characterization

    DEFF Research Database (Denmark)

    Yang, Chiming; Plackett, David; Needham, David

    2009-01-01

    To develop and characterize the solid-state properties of poly(DL-lactic-co-glycolic acid) (PLGA) and poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV) microspheres for the localized and controlled release of fusidic acid (FA). The effects of FA loading and polymer composition on the mean...... diameter, encapsulation efficiency and FA released from the microspheres were determined. The solid-state and phase separation properties of the microspheres were characterized using DSC, XRPD, Raman spectroscopy, SEM, laser confocal and real time recording of single microspheres formation. Above a loading...... of 1% (w/w) FA phase separated from PLGA polymer and formed distinct spherical FA-rich amorphous microdomains throughout the PLGA microsphere. For FA-loaded PLGA microspheres, encapsulation efficiency and cumulative release increased with initial drug loading. Similarly, cumulative release from FA...

  6. Evaluation of glibenclamide microspheres for sustained release

    Directory of Open Access Journals (Sweden)

    Kambham Venkateswarlu

    2017-04-01

    Full Text Available Context: Sustained release drug delivery systems are more preferred than the conventional drug delivery systems due to its enhanced bioavailability and patient compliance. Earlier studies reported on glibenclamide (GBCM were not clear and hence, the step has been taken to explore the sustained release drug delivery system of GBCM. Aims: To evaluate the sustained release microspheres obtained of GBCM. Methods: Microspheres were prepared by ionic gelation method using the polymers like Eudragit RS 100 and xanthan gum. Polymers can sustain the drug release from microspheres. The prepared microspheres were subjected to micromeritic studies like Carr’s index, Hausner’s ratio and angle of repose. Results: Micromeritic studies confirmed that the microspheres possessing acceptable flow properties. It was observed from the in vitro release studies, formulations F8 and F9 showed sustained drug release for desired time of 12 h and when compared to F9, formulation F8 showed maximum drug release for 12 h. Conclusions: Results confirmed the formulation F8 consist of the polymers such as Eudragit RS 100 about 150 mg and xanthan gum about 100 mg showed desired sustained release of 12 h with 96.07% and kinetic studies confirmed that the release from microspheres followed non-Fickian diffusion mechanism. Due to its sustained release property, it could enhance the bioavailability of drug thereby improves the patient compliance and expect better treatment than conventional dosage forms.

  7. Study on the Degradation of Polylactide Microsphere In Vitro

    Institute of Scientific and Technical Information of China (English)

    HeYing; WeiShuli

    2001-01-01

    This report concentrated on the rules and mechanism of the degradation of polylactide and the microspheres. The rate of degradation was assessed with five methods: observation of microsphere surface morphology by SEM, determination of the weight loss of the microspheres, determination of the molecular mass of the polymers by GPC, determination of pH and determination of the contents of lactic acid by UV spectrophotometry. The degradation of polylactide microspheres showed two-phase characteristics. At the early stage of the degradation, the high molecular mass polymers were cleaved into lower molecular mass fractions and at the late stage, there was a period of erosion and weight loss of the microspheres. The degradation was much slower for polymers with a higher molecular mass. The polylactide degradation showed good regularity.

  8. Design and Preparation of Hairy Polymer Microspheres%毛发状高分子微球的设计与制备

    Institute of Scientific and Technical Information of China (English)

    张龙; 常成明; 周芳名; 任淑萍; 石山

    2016-01-01

    First,the monodisperse micron-sized polystyrene(PS) particles were prepared by dispersion polymerization using methanol as the dispersion medium,polyvinylpyrrolidone( PVP) as the stabilizer,and azobisisobutyronitrile( AIBN) as the initiator.Then,the as-synthesized PS particles were used as seed par-ticles for the preparation of PS/Poly ( styrene-co-4-vinylbenzyl N, N-diethyldithiocarbamate ) [ PS/Poly ( St-co-VBDC) ] composite particles using seeded soap-free emulsion polymerization with St and VBDC ( used as a kind of polymerable iniferter) as monomers.Finally,under the irradiation of UV,poly( acrylic acid) ( PAA) with different chain length was grafted onto the surface of PS/Poly( St-co-VBDC) particles by living radical polymerization.The resulted polymer particles were characterized by dynamic light scattering(DLS),IR,transmission electron microscopy(TEM),scanning electron microscopy(SEM),and so on.%以甲醇为分散介质、聚乙烯基吡咯烷酮( PVP)为分散剂、偶氮二异丁腈( AIBN)为引发剂,采用分散聚合法制备出单分散微米级聚苯乙烯( PS)微球。通过种子无皂乳液聚合法,以PS微球为种子、过硫酸钾( KPS)为引发剂,将一种可聚合光引发转移终止剂二乙基二硫代氨基甲酸对乙烯基苄酯( VBDC)和苯乙烯( St)的共聚物负载到PS种子微球表面,得到PS/Poly( St-co-VBDC)微球。通过活性自由基聚合在PS/Poly(St-co-VBDC)微球表面用紫外光引发接枝聚丙烯酸(PAA),制备一系列表面接枝不同长度PAA的PS/Poly(St-co-VBDC)毛发状微球。利用动态光散射(DLS)、红外光谱( IR)、扫描电子显微镜( SEM)、透射电子显微镜( TEM)等多种方法对所得各种高分子微球进行了详细表征。

  9. Hydrophilic gallic acid-imprinted polymers over magnetic mesoporous silica microspheres with excellent molecular recognition ability in aqueous fruit juices.

    Science.gov (United States)

    Hu, Xin; Xie, Lianwu; Guo, Junfang; Li, Hui; Jiang, Xinyu; Zhang, Yuping; Shi, Shuyun

    2015-07-15

    Hydrophilic molecularly imprinted polymers (MIPs) for gallic acid (GA) were prepared with excellent recognition ability in an aqueous solution. The proposed MIPs were designed by self-polymerization of dopamine (DA) on magnetic mesoporous silica (Fe3O4@SiO2@mSiO2, MMS) using GA as template. Resulting Fe3O4@SiO2@mSiO2@MIPs (MMS-MIPs) were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), vibrating sample magnetometer (VSM), and evaluated by adsorption isotherms/kinetics and competitive adsorption. The adsorption behavior between GA and MMS-MIPs followed Langmuir and Sips adsorption isotherms with a maximum adsorption capacity at 88.7 mg/g and pseudo-second-order reaction kinetics with fast binding (equilibrium time at 100 min). In addition, MMS-MIPs showed rapid magnetic separation (10 s) and stability (retained 95.2% after six cycles). Subsequently, MMS-MIPs were applied for the selective extraction and determination of GA from grape, apple, peach and orange juices (4.02, 3.91, 5.97, and 0.67 μg/g, respectively). Generally, the described method may pave the way towards rationally designing more advanced hydrophilic MIPs.

  10. Compression molding of aerogel microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Pekala, Richard W. (Pleasant Hill, CA); Hrubesh, Lawrence W. (Pleasanton, CA)

    1998-03-24

    An aerogel composite material produced by compression molding of aerogel microspheres (powders) mixed together with a small percentage of polymer binder to form monolithic shapes in a cost-effective manner. The aerogel composites are formed by mixing aerogel microspheres with a polymer binder, placing the mixture in a mold and heating under pressure, which results in a composite with a density of 50-800 kg/m.sup.3 (0.05-0.80 g/cc). The thermal conductivity of the thus formed aerogel composite is below that of air, but higher than the thermal conductivity of monolithic aerogels. The resulting aerogel composites are attractive for applications such as thermal insulation since fabrication thereof does not require large and expensive processing equipment. In addition to thermal insulation, the aerogel composites may be utilized for filtration, ICF target, double layer capacitors, and capacitive deionization.

  11. Compression molding of aerogel microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Pekala, R.W.; Hrubesh, L.W.

    1998-03-24

    An aerogel composite material produced by compression molding of aerogel microspheres (powders) mixed together with a small percentage of polymer binder to form monolithic shapes in a cost-effective manner is disclosed. The aerogel composites are formed by mixing aerogel microspheres with a polymer binder, placing the mixture in a mold and heating under pressure, which results in a composite with a density of 50--800 kg/m{sup 3} (0.05--0.80 g/cc). The thermal conductivity of the thus formed aerogel composite is below that of air, but higher than the thermal conductivity of monolithic aerogels. The resulting aerogel composites are attractive for applications such as thermal insulation since fabrication thereof does not require large and expensive processing equipment. In addition to thermal insulation, the aerogel composites may be utilized for filtration, ICF target, double layer capacitors, and capacitive deionization. 4 figs.

  12. Coacervate droplets, proteinoid microspheres, and the genetic apparatus

    Science.gov (United States)

    Fox, S. W.

    1974-01-01

    Differences between typical coacervate droplets and typical proteinoid microspheres are examined. It is pointed out that coacervate droplets are produced from polymers obtained from contemporary organisms. The microspheres considered are aggregates of proteinoid formed from monomeric amino acids under geologically relevant conditions. Aspects regarding the primordial sequence are discussed along with the origin of the genetic apparatus and the genetic code.

  13. Mesoporous phenylalanine ammonia lyase microspheres with improved stability through calcium carbonate templating.

    Science.gov (United States)

    Cui, Jiandong; Zhao, Yamin; Tan, Zhilei; Zhong, Cheng; Han, Peipei; Jia, Shiru

    2017-05-01

    Cross-linked enzyme aggregates (CLEAs) have recently emerged as a promising method for enzyme immobilization due to its simplicity and low cost. However, a lack of good size and morphological control over the as-prepared CLEAs has limited their practical applications in some cases. Here, monodisperse spherical CLEAs of phenylalanine ammonia lyase (PAL microspheres) were prepared based on CaCO3 microtemplates. The preparation procedure involves filling porous CaCO3 microtemplates with the protein by salt precipitation, glutaraldehyde crosslinking, and dissolution of the microtemplates. The formulation of CaCO3 templates with controlled size was studied in detail. Characterization of the prepared PAL microspheres was investigated. The results showed that the PAL microspheres with high immobilization efficiency (79%) exhibited excellent stability, including increased tolerance to proteolysis, low pH, and denaturants, and excellent mechanical properties. For example, free PAL almost lost all activity after they were incubated in the presence of trypsin for 2min, whereas PAL microspheres still retained 95% of their initial activity. Moreover, scanning electron microscope, transmission electron microscope, and N2 adsorption-desorption isotherms revealed that the resultant PAL microspheres possessed good monodispersity and mesoporous structure instead of the amorphous clusters of conventional CLEAs with few pores. Compared with conventional CLEAs, the monodisperse PAL microspheres with mesoporous make them more potentially useful for biomedical and biotechnological applications.

  14. 替米考星β-环糊精聚合物微球的制备与表征%Preparation and Characterization of Tilmicosin β-Cyclodextrin Polymer Microspheres Inclusion Compound

    Institute of Scientific and Technical Information of China (English)

    李仲谨; 韩春鹏; 苗宗成; 赵燕; 杨威; 赵艳

    2011-01-01

    [ Objective ]To optimize the preparation technology of Tilmicosin β-cyclodextrin polymer micro-spheres inclusion compound. [ Method] Tilmicosin β-cyclodextrin polymer microspheres inclusion compound was prepared by coprecipitation method. The preparation process was optimized through the L9(34) orthogonal experimental design, the regression analysis was based on the evaluation indicators of drug produce and encapsulation efficiency. Tilmicosin β-cyclodextrin polymer microspheres inclusion compound was characterized by SEM,laser particle analyzer,FT-IR spectroscopy and thermo gravimetric analysis (TGA). [ Result]The best technological conditions were showed as following: the quantity of β-cyclodextrin polymer mierospheres,Tilmicosin were 3 g,0.25 g respectively,the reacting temperature was 50 ℃, the reacting time was 3 h, stirring speed was 600 r/min. Under optimum conditions, the produce and drug encapsulation efficiency were 83.32% and 67.61% respectively.Through optimizing the preparation process,the loaded microspheres were endowed with good shape,and the average diameter of microparticle was 161.35 μm. Tilmicosin was dispersed with amorphous in microspheres,and it was ensured with good thermal stability. [ Conclusion ]The preparation method was reasonable and feasible.%[目的]优化替米考星β-环糊精聚合物(β-CDP)微球的制备工艺.[方法]采用共沉淀法制备替米考星β-CDP微球,以包封率和产率的回归分析综合得分为指标,通过L9(34)正交试验设计对制备工艺进行优化;采用扫描电镜、激光粒度分布仪、红外光谱仪和综合热分析仪对替米考星β-CDP微球进行表征.[结果]最佳工艺条件为:β-CDP微球3 g、替米考星 0.25 g、反应温度50 ℃、反应时间1 h、搅拌速度600 r/min;在最佳工艺条件下:产率为83.32%,包封率为67.61%.以优化工艺制备的载药微球形态良好,平均粒径为 161.35 μm;替米考星进入到β-CDP微球中的内部,且以无定

  15. Hybrid microspheres

    Science.gov (United States)

    Rembaum, Alan (Inventor); Yen, Richard C. K. (Inventor)

    1985-01-01

    Substrates, particularly inert synthetic organic resin beads (10) or sheet (12) such as polystyrene are coated with a covalently bound layer (24) of polyacrolein by irradiation a solution (14) of acrolein or other aldehyde with high intensity radiation. Individual microspheres (22) are formed which attach to the surface to form the aldehyde containing layer (24). The aldehyde groups can be converted to other functional groups by reaction with materials such as hydroxylamine. Adducts of proteins such as antibodies or enzymes can be formed by direct reaction with the surface aldehyde groups.

  16. Preparation of Micron-size Functional Fluorescent Microspheres

    Institute of Scientific and Technical Information of China (English)

    WANG Di-qiang; LIU Bai-ling; LI He; HU Jie

    2004-01-01

    As a kind of special functional microspheres, fluorescent polymer microspheres could be used in cell label and separation, blood flow assay, flow cytometer marking, chemical reaction assay,and in analyst of the transform and diffusion of particles in soil 1. However, one of the most important applications of fluorescent microspheres is in the high-throughput screening of drugs (HTS) 2. Through affinity interaction, radioactive ligands (latent drugs) are bound to fluorescent microspheres covered by receptor, and luminescence is produced by radioactivity, so ligands can be assayed and screened.In this study, we developed a technique for preparing micron-size fluorescent microspheres with different functional groups. The methods included the synthesis of micron-size polystyrene microspheres through the dispersion polymerization of styrene in different media such as ethanol,ethanol-water, and isopropanol; the functional polystyrene microspheres were prepared by introduction of functional monomers into the reaction system of styrene; the functional fluorescent microspheres were obtained by the way of dying functional microspheres in the fluorescent material's ethanol solvent.The average diameter of microspheres was in the range of 1~10 μm, and the distribution was normal distribution. The functional groups included -OH, -CHO, -COOH, -CONH2, and SO3H. The absorbing spectrum and exciting spectrum were tested, the results showed that the maximal absorbance of fluorescent microsphere was near 306.5 nm, and its maximal excitation was near 362 nm. The excitation spectrum of fluorescent material (DPO) and fluorescent microspheres were shown in figure 1, and it indicated that the developed fluorescent microspheres showed the same excitation behavior like DPO, which related to the fluorescent microspheres had stable luminescence property.

  17. Preparation and Characterization of Monodisperse Nickel Nanoparticles by Polyol Process

    Institute of Scientific and Technical Information of China (English)

    LI Peng; GUAN Jianguo; ZHANG Qingjie; ZHAO Wenyu

    2005-01-01

    Polymer-protected monodisperse nickel nanoparticles were synthesized by a modified polyol reduction method in the presence of poly ( N-vinyl- 2-pyrrolidone ). These nanoparticles were characterized by transmission electron microscopy (TEM), X- ray diffraction ( XRD ), selected area electron diffraction ( SAED ), as well as vibrating sample magnetometer (VSM). The experimental results show that the addition of PVP and the concentration of NaOH have strong influences on the size, agglomeration and uniformity of nanoparticles. In the presence of PVP and NaOH with low concentrations, monodisperse nickel nanoparticles with average diameters about 42 nm were obtained and characterized to be pure nickel crystalline with fcc structure. Secondary structures such as clusters, loops, and strings resulted from magnetic interactions between particles were observed. The chemical interaction between the PVP and nickel nanoparticles was found by FTIR. The saturation magnetization ( Ms ), remanent magnetization (Mr) and coercivity ( Hc ) of these nickel nanoparticles are lower than those of bulk nickel.

  18. CHARACTERIZATION OF CAPTOPRIL-ETHYL CELLULOSE MICROSPHERES BY THERMAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    RakeshGupta

    2010-06-01

    Full Text Available The objective of the present study was to study the physical characterization of Captopril-ethyl cellulose microspheres by thermal analysis such as Differential Scanning Calorimetry (DSC, Differential thermal analysis (DTA and Thermo gravimetry (TG. Drug polymer interaction can directly affect the dosage form stability, drug encapsulation into polymers and dissolution patterns. In this study thermal analysis has been carried out for the physical mixtures and microspheres of captopril and ethyl cellulose prepared by solvent evaporation method.

  19. Mucoadhesive Microsphere - Review

    Directory of Open Access Journals (Sweden)

    Ratnaparkhi M P

    2014-06-01

    Full Text Available Several approaches have been immerged to prolong the residence time of the dosage forms at the absorption site and one of them is the development of oral controlled release mucoadhesive system. Mucoadhesive drug delivery systems are used to enhance drug absorption in a site-specific manner. Bioadhesion has been defined as the attachment of synthetic or biological macromolecules to a biological tissue. The biological surface can be epithelial tissue or the mucous coat on the surface of a tissue. If adhesive attachment is to a mucous coat, the phenomenon is referred to as mucoadhesion. Mucus is a thin blanket covering all epithelia that are in contact with the external environment in the gastrointestinal, respiratory, and urogenital tracts. This approach involves the use of mucoadhesive polymers, which can adhere to the epithelial surface in the stomach. Carrier technology offers an intelligent approach for drug delivery by coupling the drug to a carrier particle such as microspheres, nanospheres, liposomes, nanoparticles, etc., which modulates the release and absorption of the drug. Microspheres constitute an important part of these particulate drug delivery systems by virtue of their small size and efficient carrier capacity.

  20. Molecularly imprinted microspheres prepared by precipitation polymerization at high monomer concentrations

    Directory of Open Access Journals (Sweden)

    Renkecz Tibor

    2014-01-01

    Full Text Available Highly crosslinked polymer microparticles have been prepared by precipitation polymerization using high monomer loadings (≥25 v/v % which generally would lead to bulk monoliths. The microparticle format was achieved by the use of non-solvating diluents either alone or in combination with co-solvents. Two distinct morphologies were observed. Monodisperse smooth microspheres were obtained using a thermodynamically good co-solvent whereas segmented irregular particles were formed with poorer co-solvents. It has been found that during polymerization the forming polymer particles were enriched in the co-solvent and this effect was more pronounced when good co-solvents were used. The type of functional monomer, crosslinker and co-solvent, and the non-solvent/co-solvent ratio were identified as influential parameters on the microparticle morphology. With the proposed methodology molecularly imprinted microparticles have been prepared successfully for three different templates, naproxen, diclofenac and toltrazuril using various functional monomers, crosslinkers and polymerization solvent mixtures.

  1. Aerosol fabrication methods for monodisperse nanoparticles

    Science.gov (United States)

    Jiang, Xingmao; Brinker, C Jeffrey

    2014-10-21

    Exemplary embodiments provide materials and methods for forming monodisperse particles. In one embodiment, the monodisperse particles can be formed by first spraying a nanoparticle-containing dispersion into aerosol droplets and then heating the aerosol droplets in the presence of a shell precursor to form core-shell particles. By removing either the shell layer or the nanoparticle core of the core-shell particles, monodisperse nanoparticles can be formed.

  2. One-step synthesis and properties of urchin-like PS/α-Fe2O3 composite hollow microspheres

    Science.gov (United States)

    Zhang, Yanping; Chu, Ying; Dong, Lihong

    2007-10-01

    A new progressive hard template method has been developed to synthesize uniform polystyrene (PS)/α-Fe2O3 composite hollow microspheres under hydrothermal conditions. Sulfonated polystyrene (PS) microspheres were used as templates as well as the endothecia of the composite microspheres; Fe2O3 shell was obtained through the reaction of FeSO4 and KClO3 under hydrothermal conditions. Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) studies showed that the as-obtained products consist of large scale monodisperse urchin-like hollow microspheres. In comparison with the Fe2O3 of other structures, the composite hollow microspheres have good photocatalytic activity, large surface area and a high remanent magnetization. A possible mechanism for the formation of composite hollow microspheres is also proposed in the paper.

  3. 替米考星β-CDP载药微球的制备及释药性能研究%Study on Preparation and Drug Release of Tilmicosin β-Cyclodextrin Polymer Microspheres

    Institute of Scientific and Technical Information of China (English)

    杨黎燕; 余丽丽; 姚琳; 尤静

    2013-01-01

    采用共沉淀法制备了替米考星β-CDP载药微球,讨论了投药比、反应时间、反应温度对替米考星β-CDP载药微球的影响,并探讨了其体外释药情况,运用红外光谱仪、电镜、粒度分析仪对产物进行了表征.结果表明,在β-CDP微球质量为3 g、替米考星质量为0.25 g、反应温度为50℃、反应时间为1.0h、搅拌速度为400 r· min-1的条件下制得的载药微球的产率为81.60%、包封率为66.05%.替米考星β-CDP载药微球粒径分布均匀,外观圆整,在pH值为7.4的PBS中释药效果较好.载药微球释药与Korsmeyer-Peppas方程有较好拟合.%Tilmicosin β-cyclodextrin polymer (β-CDP) microspheres was prepared by coprecipitation method. The influence of preparation conditions on tilmicosin β-CDP microspheres and its drug release in vitro were investigated. Fourier transform infrared spectroscopy (IR) .scanning electron microscopy (SEM) and granularity analyzer were used to character tilmicosin β-CDP microspheres. The results showed that the optimum preparation conditions were as follows:the quantity of β-CDP was 3 g"the quantity of tilmicosin was 0. 25 g,the reaction temperature was 50℃.the reaction time was 1. 0 h.the stirring speed was 400 r·min-1 The yield and drug encapsulation rate were 81. 60% and 66.05%, respectively under above conditions. The tilmicosin β-CDP microspheres was uniform in particle size distribution, was round in appearance,and had a good drug release in PBS(pH = 7. 4). And Korsmeyer-Peppas equation was adapted for its drug release characteristic.

  4. 香兰素分子印迹微球的制备及识别机理%Preparation and Recognition Mechanism of Vanillin Molecularly Imprinted Polymer Microspheres

    Institute of Scientific and Technical Information of China (English)

    王深旗; 彭海龙; 熊华; 阮霞; 黄声芳; 董丽玲

    2012-01-01

    以香兰素(Van)为模板、甲基丙烯酸(MAA)为功能单体、偶氮二异丁腈(AIBN)为引发剂和乙烯二醇二甲基丙烯酸酯(EDMA)为交联剂,采用沉淀聚合法合成一种新型的对Van有特异识别功能的分子印迹聚合物微球(MIPs)。通过UV、傅里叶变换红外光谱仪(FT-IR)和1H NMR光谱法研究模板与功能单体之间的相互作用和识别机理,采用扫描电镜(SEM)考察MIPs表面形态,通过平衡和等温吸附实验对MIPs和非分子印迹微球(NIPs)吸附性能进行研究。结果表明:MAA与Van之间通过氢键相互作用,MIPs具有表面光滑的规则球状结构,MIPs对Van的吸附和识别能力远高于NIPs,并且在120min后达到吸附平衡状态,Scatchard分析表明在MIPs上形成了均匀的对Van有特异性的结合位点,最大表观吸附量Qmax和平衡离解常数Kd分别为7.357μmol/g和4.243×10-5mol/L;选择性分离、分子印迹固相萃取(MIP-SPE)和HPLC实验分析表明,MIPs对Van具有很好的分离和富集能力。%Molecularly imprinted microspheres(MIPs) were synthesized by precipitation polymerization using vanillin as template molecule,methacrylic acid(MAA) as functional monomer,azodiisobutyronitrile(AIBN) as initiator and ethylene glycol dimethacrylate as cross-linker.The interaction of vanillin with MAA and the recognition mechanism of vanillin MIPs were studied by UV spectroscopy,Fourier transform infrared spectroscopy(FT-IR) and 1H-NMR,and their surface morphology was observed under a scanning electron microscope(SEM).Equilibrium adsorption and isothermal adsorption experiments were carried out to investigate the vanillin-binding capacities of MIPs and non-molecularly imprinted polymers(NIPs).Smooth and regularly shaped MIPs were formed from the hydrogen bonding interaction between vanillin and MAA.They could adsorb and recognize vanillin much better than NIPs and adsorption equilibrium was reached after 120 min

  5. A novel strategy for the preparation of porous microspheres and its application in peptide drug loading.

    Science.gov (United States)

    Wei, Yi; Wang, Yuxia; Zhang, Huixia; Zhou, Weiqing; Ma, Guanghui

    2016-09-15

    A new strategy is developed to prepare porous microspheres with narrow size distribution for peptides controlled release, involving a fabrication of porous microspheres without any porogens followed by a pore closing process. Amphiphilic polymers with different hydrophobic segments (poly(monomethoxypolyethylene glycol-co-d,l-lactide) (mPEG-PLA), poly(monomethoxypolyethylene glycol-co-d,l-lactic-co-glycolic acid) (mPEG-PLGA)) are employed as microspheres matrix to prepare porous microspheres based on a double emulsion-premix membrane emulsification technique combined with a solvent evaporation method. Both microspheres possess narrow size distribution and porous surface, which are mainly caused by (a) hydrophilic polyethylene glycol (PEG) segments absorbing water molecules followed by a water evaporation process and (b) local explosion of microspheres due to fast evaporation of dichloromethane (MC). Importantly, mPEG-PLGA microspheres have a honeycomb like structure while mPEG-PLA microspheres have a solid structure internally, illustrating that the different hydrophobic segments could modulate the affinity between solvent and matrix polymer and influence the phase separation rate of microspheres matrix. Long term release patterns are demonstrated with pore-closed microspheres, which are prepared from mPEG-PLGA microspheres loading salmon calcitonin (SCT). These results suggest that it is potential to construct porous microspheres for drug sustained release using permanent geometric templates as new porogens.

  6. Preparation of polysulfone hollow microspheres encapsulating DNA and their functional utilization.

    Science.gov (United States)

    Zhao, C; Liu, X D; Nomizu, M; Nishi, N

    2004-05-01

    Polysulfone hollow microspheres encapsulating DNA were prepared using a liquid-liquid phase separation technique. The microspheres were then used to absorb a DNA-binding intercalating material--ethidium bromide. The amount of DNA encapsulated in the microspheres depended on the concentration of the DNA solution used to prepare the microspheres, and the microsphere morphology depended on both the polymer concentration and the preparation conditions. The amount of ethidium bromide in the microspheres depended mainly on the amount of encapsulated DNA, and the microsphere morphology also affected the removal of the ethidium bromide. The new method of DNA encapsulation is proposed, and the microspheres encapsulating the DNA have the potential to be used in environmental applications.

  7. 盐酸小檗碱β-环糊精微球的制备及体外释药研究%Preparation and the berberine hydrochloride release behavior in vitro of β-cyclodextrin polymer microspheres

    Institute of Scientific and Technical Information of China (English)

    尤静; 余丽丽; 杨黎燕

    2013-01-01

    β-Cyclodextrin polymer microspheres (β-CDP) were obtained using epichlorohydrin as a crosslinking agent by inverse emulsion polymerization method and berberine hydrochloride β-cyclodextrin polymer microspheres ( BH-β-CDP) by co-precipitation method. BH-β-CDP of the drug release process were researched in the gastrointestinal environment. The results showed that the encapsulation efficiency of BH-β-CDPM was 70. 12% ;and the release rate of drug from BH-β-CDPM is much slowly in the intestinal environment than in the gastric environment. BH-β-CDP(20: 1) of drug release process in the intestinal environment attached both first-order kinetic equation and Korsmeyer-Peppas equation, which indicated that the drug release mainly is simple diffusion.%以环氧氯丙烷为交联剂用反相乳液聚合法制得β-环糊精微球,共沉淀法制备盐酸小檗碱β-环糊精微球(BH-β-CDP).研究了胃肠环境下BH-β-CDP的体外释药行为.结果表明,微球对盐酸小檗碱的最大包封率可达70.12%;肠环境下释药比较缓慢;BH-β-CDP(20:1)在胃肠环境中的释药动力学过程符合一级动力学和KorsmeyerPeppas模型,说明BH-β-CDP的释放机制为单纯扩散为主,Fick扩散为辅.

  8. Formulation, optimization and evaluation of sustained release microsphere of ketoprofen

    Directory of Open Access Journals (Sweden)

    V Chirag Prajapati

    2012-01-01

    Full Text Available The objective of this study is to formulate ketoprofen loaded microspheres of Acrycoat S100 by an o/w emulsion solvent evaporation method. It potently inhibits the enzyme cyclooxygenase resulting in prostaglandin synthesis inhibition. Ketoprofen causes an irritation in the gastrointestinal mucous membrane and possesses a bitter taste and aftertaste. The half-life in plasma is about 1-2hrs. This makes ketoprofen a very good candidate for the formulation of controlled release dosage forms. Ketoprofen microspheres help to protect the gastric mucous membrane from drug irritation and to mask its taste. The prepared microspheres were evaluated for micromeritic properties, particle size, effect of surfactant concentration, percentage yield, incorporation efficiency, drug polymer compatibility (IR and DSC study, scanning electron microscopy and in vitro drug release. The microspheres produced exhibited good encapsulation efficiencies and micromeritic properties. Encapsulation efficiency of microsphere is around 78%. The mean diameters of microspheres were found in required micrometer range. The results of optimized formulations showed a narrow size distribution and smooth surface. The DSC and the FTIR analysis showed the absence of any potent incompatibility between the drug and the polymer. In-vitro release showed 86.4% drug release after 12 hours. Results of present study suggest that Acrycoat S100 loaded microsphere of ketoprofen can be successfully designed to develop sustained drug delivery system. The solvent evaporation method is a suitable technique for the preparation of Acrycoat S100 microspheres for controlling the release of Ketoprofen for a prolonged duration.

  9. Design of sustained-release nitrendipine microspheres having solid dispersion structure by quasi-emulsion solvent diffusion method

    DEFF Research Database (Denmark)

    Cui, Fude; Yang, Mingshi; Jiang, Yanyan

    2003-01-01

    To improve the bioavailability of nitrendipine microspheres, a sustained-release microspheres having solid dispersion structure were prepared in one step. Two types of polymer, i.e. solid dispersing and sustained-release polymers, were employed to prepare the microspheres by the spherical...... crystallization technique, i.e. quasi-emulsion solvent diffusion method. The factors of effect on micromeritic properties and release profiles of the resultant microspheres were investigated. And the bioavailability of nitrendipine microspheres was evaluated in six healthy dogs. The results showed...... that the particle size of microspheres was determined mainly by the agitation speed. The dissolution rate of nitrendipine from microspheres was enhanced significantly with increasing the amount of dispersing agents, and sustained by adding retarding agents. The release rate of microspheres could be controlled...

  10. Controlled Delivery of Gentamicin Using Poly(3-hydroxybutyrate Microspheres

    Directory of Open Access Journals (Sweden)

    Ipsita Roy

    2011-07-01

    Full Text Available Poly(3-hydroxybutyrate, P(3HB, produced from Bacillus cereus SPV using a simple glucose feeding strategy was used to fabricate P(3HB microspheres using a solid-in-oil-water (s/o/w technique. For this study, several parameters such as polymer concentration, surfactant and stirring rates were varied in order to determine their effect on microsphere characteristics. The average size of the microspheres was in the range of 2 µm to 1.54 µm with specific surface areas varying between 9.60 m2/g and 6.05 m2/g. Low stirring speed of 300 rpm produced slightly larger microspheres when compared to the smaller microspheres produced when the stirring velocity was increased to 800 rpm. The surface morphology of the microspheres after solvent evaporation appeared smooth when observed under SEM. Gentamicin was encapsulated within these P(3HB microspheres and the release kinetics from the microspheres exhibiting the highest encapsulation efficiency, which was 48%, was investigated. The in vitro release of gentamicin was bimodal, an initial burst release was observed followed by a diffusion mediated sustained release. Biodegradable P(3HB microspheres developed in this research has shown high potential to be used in various biomedical applications.

  11. STRUCTURING OF DIAMOND FILMS USING MICROSPHERE LITHOGRAPHY

    Directory of Open Access Journals (Sweden)

    Mária Domonkos

    2014-10-01

    Full Text Available In this study, the structuring of micro- and nanocrystalline diamond thin films is demonstrated. The structuring of the diamond films is performed using the technique of microsphere lithography followed by reactive ion etching. Specifically, this paper presents a four-step fabrication process: diamond deposition (microwave plasma assisted chemical vapor deposition, mask preparation (by the standard Langmuir-Blodgett method, mask modification and diamond etching. A self-assembled monolayer of monodisperse polystyrene (PS microspheres with close-packed ordering is used as the primary template. Then the PS microspheres and the diamond films are processed in capacitively coupled radiofrequency plasma  using different plasma chemistries. This fabrication method illustrates the preparation of large arrays of periodic and homogeneous hillock-like structures. The surface morphology of processed diamond films is characterized by scanning electron microscopy and atomic force microscope. The potential applications of such diamond structures in various fields of nanotechnology are also briefly discussed.

  12. 当归精油β-环糊精微球的制备及其性能研究%The preparation and performance of angelica oil β-cyclodextrin polymer microspheres inclusion compound

    Institute of Scientific and Technical Information of China (English)

    尤静; 杨黎燕; 余丽丽

    2014-01-01

    β-Cyclodextrin Polymer microsPheres(β-CDP)were obtained by inverse emulsion Polymerization method and angelica oilβ-cyclodextrin Polymer microsPheres by saturated water solution method. The drug release behavior in vitro was studied. The result have shown that the encaPsulation efficiency was 75%. The drug release Profile could be described by Higuchi equation and Korsmeyer-PePPas equation,which indicated that the drug release mainly is simPle diffusion,and the heat stabilization is nice.%采用反相乳液聚合法制备β-环糊精微球(β-CDP),饱和水溶液法包合当归精油,并研究其体外释药行为。结果表明,微球对当归精油的包合率可达75%,包合效果良好,体外释药行为符合Higuchi和Korsmeyer-PePPas模型方程,说明当归精油微球释放机制以单纯扩散为主,具有一定缓释效果,且热稳定性良好。

  13. BIOCOMPATIBLE FLUORESCENT MICROSPHERES: SAFE PARTICLES FOR MATERIAL PENETRATION STUDIES

    Energy Technology Data Exchange (ETDEWEB)

    Farquar, G; Leif, R

    2009-07-15

    Biocompatible polymers with hydrolyzable chemical bonds have been used to produce safe, non-toxic fluorescent microspheres for material penetration studies. The selection of polymeric materials depends on both biocompatibility and processability, with tailored fluorescent properties depending on specific applications. Microspheres are composed of USFDA-approved biodegradable polymers and non-toxic fluorophores and are therefore suitable for tests where human exposure is possible. Micropheres were produced which contain unique fluorophores to enable discrimination from background aerosol particles. Characteristics that affect dispersion and adhesion can be modified depending on use. Several different microsphere preparation methods are possible, including the use of a vibrating orifice aerosol generator (VOAG), a Sono-Tek atomizer, an emulsion technique, and inkjet printhead. Applications for the fluorescent microspheres include challenges for biodefense system testing, calibrants for biofluorescence sensors, and particles for air dispersion model validation studies.

  14. Microsphere-Based Rapamycin Delivery, Systemic Versus Local Administration in a Rat Model of Renal Ischemia/Reperfusion Injury

    NARCIS (Netherlands)

    Zandstra, Jurjen; van Beuge, Marike M.; Zuidema, Johan; Petersen, Arjen H.; Staal, Mark; Duque, Luisa F.; Rodriguez, Sergio; Lathuile, Audrey A. R.; Veldhuis, Gert J.; Steendam, Rob; Bank, Ruud A.; Popa, Eliane R.

    2015-01-01

    The increasing prevalence and treatment costs of kidney diseases call for innovative therapeutic strategies that prevent disease progression at an early stage. We studied a novel method of subcapsular injection of monodisperse microspheres, to use as a local delivery system of drugs to the kidney. W

  15. Packaged chalcogenide microsphere resonator with high Q-factor

    Science.gov (United States)

    Wang, Pengfei; Ding, Ming; Lee, Timothy; Senthil Murugan, Ganapathy; Bo, Lin; Semenova, Yuliya; Wu, Qiang; Hewak, Dan; Brambilla, Gilberto; Farrell, Gerald

    2013-04-01

    The fabrication and characterization of a packaged As2S3 microsphere resonator coupled to a tapered fiber using a low refractive index UV-curable polymer are reported. Embedding provides an efficient means to remove the highest order whispering gallery modes in the microsphere resonator, thus cleaning the resonator spectrum. At wavelengths near 1549.5 nm, high-Q modes up to 1.8 × 105 can be efficiently excited in a 110 μm diameter chalcogenide microsphere via evanescent coupling from a 2 μm diameter tapered silica fiber. The device photosensitivity, useful for tuning, is still present and useable after the packaging process.

  16. Optimization of sustained release aceclofenac microspheres using response surface methodology.

    Science.gov (United States)

    Deshmukh, Rameshwar K; Naik, Jitendra B

    2015-03-01

    Polymeric microspheres containing aceclofenac were prepared by single emulsion (oil-in-water) solvent evaporation method using response surface methodology (RSM). Microspheres were prepared by changing formulation variables such as the amount of Eudragit® RS100 and the amount of polyvinyl alcohol (PVA) by statistical experimental design in order to enhance the encapsulation efficiency (E.E.) of the microspheres. The resultant microspheres were evaluated for their size, morphology, E.E., and in vitro drug release. The amount of Eudragit® RS100 and the amount of PVA were found to be significant factors respectively for determining the E.E. of the microspheres. A linear mathematical model equation fitted to the data was used to predict the E.E. in the optimal region. Optimized formulation of microspheres was prepared using optimal process variables setting in order to evaluate the optimization capability of the models generated according to IV-optimal design. The microspheres showed high E.E. (74.14±0.015% to 85.34±0.011%) and suitably sustained drug release (minimum; 40% to 60%; maximum) over a period of 12h. The optimized microspheres formulation showed E.E. of 84.87±0.005 with small error value (1.39). The low magnitudes of error and the significant value of R(2) in the present investigation prove the high prognostic ability of the design. The absence of interactions between drug and polymers was confirmed by Fourier transform infrared (FTIR) spectroscopy. Differential scanning calorimetry (DSC) and X-ray powder diffractometry (XRPD) revealed the dispersion of drug within microspheres formulation. The microspheres were found to be discrete, spherical with smooth surface. The results demonstrate that these microspheres could be promising delivery system to sustain the drug release and improve the E.E. thus prolong drug action and achieve the highest healing effect with minimal gastrointestinal side effects.

  17. Preparation and surface modification of magnetic poly(methyl methacrylate) microspheres

    Institute of Scientific and Technical Information of China (English)

    YANG Chengli; GUAN Yueping; XING Jianmin; LIU Junguo; AN Zhentao; LIU Huizhou

    2004-01-01

    A novel method for preparation of magnetic polymer microspheres by spraying suspension polymerization (SSP) was developed. Relatively uniform magnetic poly(methyl methacrylate) microspheres were prepared by the spraying suspension polymerization (SSP)using methyl methacrylate (MMA) as monomer, divinylbenzene (DVB) as cross-linking agent,benzoyl peroxide (BPO) as initiator and polyvinyl alcohol (PVA) as stabilizer in the presence of hydrophobic Fe3O4 magnetic fluid. The microspheres prepared were modified by surface chemical reaction. The magnetic properties and morphology of the microspheres were examined by SEM and VSM respectively. The active functional groups of microspheres were examined by infrared spectra. The results showed that microspheres with saturation magnetization of 16.8emu/g showed distinct superparamagnetic characteristics and the magnetic microspheres with a size of 10 μm were relatively uniform.

  18. INTERACTION OF ANTIGEN AND ANTIBODY ON CORE-SHELL POLYMERIC MICROSPHERES

    Institute of Scientific and Technical Information of China (English)

    Gang Li; Qing-bin Meng; Zhan-yong Li; Ying-li An; Xiao-xia Zhu

    2011-01-01

    Monodispersed microspheres with polystyrene as the core and poly(acrylamide-co-N-acryloxysuccinimide) as the shell were synthesized by a two-step surfactant-free emulsion copolymerization. The core-shell morphology of the microspheres was shown by scanning electron microscopy and transmission electron microscopy. Rabbit immunoglobulin G (as antigen) was covalently coupled onto the microspheres by the reaction between succinimide-activated ester groups on the shell of the microspheres and amino groups of the antigen molecules. The size of particles was characterized by dynamic light scattering technique and was found to vary upon bioconjugation and interaction with proteins. The binding process was shown to be specific to goat anti-rabbit immunoglobulin G (as antibody) and reversible upon the addition of free antigen into the system.

  19. Ultrasonic atomization for spray drying: a versatile technique for the preparation of protein loaded biodegradable microspheres.

    Science.gov (United States)

    Bittner, B; Kissel, T

    1999-01-01

    Bovine serum albumin (BDA) loaded microspheres with a spherical shape and smooth surface structure were successfully prepared from poly(lactide-co-glycolide) using an ultrasonic nozzle installed in a Niro laboratory spray dryer. Process and formulation parameters were investigated with respect to their influence on microsphere characteristics, such as particle size, loading capacity, and release properties. Preparation of microspheres in yields of more than 50% was achieved using an ultrasonic atomizer connected to a stream of carrier air. Microsphere characteristics could be modified by changing several technological parameters. An increased polymer concentration of the feed generated larger particles with a significantly reduced initial release of the protein. Moreover, microspheres with a smooth surface structure were obtained from the organic polymer solution with the highest viscosity. Microparticles with a low BSA loading showed a large central cavity surrounded by a thin polymer layer in scanning electron microspheres. A high protein loading led to an enlargement of the shell layer, or even to dense particles without any cavities. A continuous in vitro release pattern of BSA was obtained from the particles with low protein loading. Glass transition temperatures (Tg) of the microspheres before and after lyophilization did not differ from those of the BSA loaded particles prepared by spray drying with a rotary atomizer. Analysis of the polymer by gel permeation chromatography indicated that ultrasonication had no effect on polymer molecular weight. Molecular weight and polydispersity of the pure polymer, placebo microspheres prepared by spray drying, and placebo microspheres prepared using the ultrasonic nozzle were in the same range. In conclusion, ultrasonic atomization represents a versatile and reliable technique for the production of protein loaded biodegradable microspheres without inducing a degradation of the polymer matrix. Particle characteristics

  20. Influence of viscosity and uronic acid composition of alginates on the properties of alginate films and microspheres produced by emulsification.

    Science.gov (United States)

    Lee, Huey Ying; Chan, Lai Wah; Dolzhenko, Anton V; Heng, Paul Wan Sia

    2006-12-01

    This study investigated the influence of viscosity and uronic acid composition of alginates on the properties of alginate films and microspheres produced by emulsification. Tensile properties of films were determined while the yield, size, drug contents and release characteristics of the microspheres were examined. Tensile properties of calcium alginate matrix were significantly affected by the orientation and arrangement of the polymer chains. High viscosity alginates gave rise to higher yields and bigger microspheres. Generally, microspheres with high drug content and slower rate of drug release had high Ca2+ contents and were produced from alginates of higher viscosity. Within an alginate microsphere batch, small sized microsphere fractions had higher drug contents but showed faster drug release rates. Microspheres having a defined size range revealed great dependence of encapsulation efficiency and drug release rates on viscosity and extent of Ca2+-alginate interaction. Viscosity appeared to exert a predominant influence on the microsphere properties.

  1. Synthesis of 3D ordered macroporous indium tin oxide using polymer colloidal crystal template

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Xue'ao; MAN; Yahui; WANG; Jianfang; LIU; Changli; WU; Wenjian

    2006-01-01

    Three-dimensional (3D) ordered macroporous indium tin oxide (ITO) is prepared using a polymer colloidal crystal template that is formed by self-assembly of the monodisperse poly(methyl methacrylate) (PMMA) microspheres. The morphologies and BET surface area of the macroporous material is examined by scanning electron microscope, transmission electron microscopy and N2 adsorption/desorption. Results indicate that the macroporous material has highly ordered arrays of the uniform pores replicated from the PMMA colloidal crystal template when the polymer colloidal crystal template is removed by calcinations at 500℃. The pore diameter (about 450 nm) of macroporous ITO slightly shrank to the PMMA microspheres. The BET surface area and pore volume of the macroporous material are 389 m2·g-1 and 0.36 cm3·g-1, respectively. Moreover, the macroporous ITO, containing 5 mol% Sn and after annealing under vacuum, shows the minimum resistivity of ρ= 8.2×10-3 Ω· cm. The conductive mechanism of macroporous ITO is discussed, and it is believed that the oxygen vacancies are the major factor for excellent electrical properties.

  2. Autonomic shutdown of lithium-ion batteries using thermoresponsive microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Baginska, Marta; White, Scott R. [306 Talbot Laboratory, Department of Aerospace Engineering, University of Illinois Urbana-Champaign, Urbana, IL (United States); Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL (United States); Blaiszik, Benjamin J.; Sottos, Nancy R. [Department of Materials Science and Engineering, Materials Science and Engineering Building, University of Illinois Urbana-Champaign, Urbana, IL (United States); Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL (United States); Merriman, Ryan J. [306 Talbot Laboratory, Department of Aerospace Engineering, University of Illinois Urbana-Champaign, Urbana, IL (United States); Moore, Jeffrey S. [Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, IL (United States); Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL (United States)

    2012-05-15

    Autonomic, thermally-induced shutdown of Lithium-ion (Li-ion) batteries is demonstrated by incorporating thermoresponsive polymer microspheres (ca. 4 {mu}m) onto battery anodes or separators. When the internal battery environment reaches a critical temperature, the microspheres melt and coat the anode/separator with a nonconductive barrier, halting Li-ion transport and shutting down the cell permanently. Three functionalization schemes are shown to perform cell shutdown: 1) poly(ethylene) (PE) microspheres coated on the anode, 2) paraffin wax microspheres coated on the anode, and 3) PE microspheres coated on the separator. Charge and discharge capacity is measured for Li-ion coin cells containing microsphere-coated anodes or separators as a function of capsule coverage. For PE coated on the anode, the initial capacity of the battery is unaffected by the presence of the PE microspheres up to a coverage of 12 mg cm{sup -2} (when cycled at 1C), and full shutdown (>98% loss of initial capacity) is achieved in cells containing greater than 3.5 mg cm{sup -2}. For paraffin microspheres coated on the anode and PE microspheres coated on the separator, shutdown is achieved in cells containing coverages greater than 2.9 and 13.7 mg cm{sup -2}, respectively. Scanning electron microscopy images of electrode surfaces from cells that have undergone autonomic shutdown provides evidence of melting, wetting, and resolidification of PE into the anode and polymer film formation at the anode/separator interface. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Preparation and characterization of porous titania-grafted poly(styrene-divinylbenzene)/maleic anhydride nanocomposite microspheres

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Mesoporous titania-grafted poly(styrene-divinylbenzene)/maleic anhydride [P(St-DVB)/MA] nanocomposite microspheres were prepared by an open ring reaction method.The titania nanoparticles were first modified by attachment of amino groups to their surface to prevent particle aggregation,and to allow the nanoparticles to covalently bond the polymer microspheres,the surface of which was modified by attachment of MA functional groups to enable the polymer to retain their porous structures and to react with the amino groups on the surface of the titania particles.The porous nanocomposite microspheres were detected by FTIR,SEM,TEM,XRD and UV-Vis spectrophotometry.The results indicated that the nanocomposite microspheres were composed of nanosized titania uniformly distributed on the surface,and exhibited better UV absorbing property than pure polymer microspheres or unmodified titania.Furthermore,compared with pure porous polymer microspheres,the nanocomposite microspheres showed more efficient UV protection and slow release of Parsol-1789(a photo-reactive and cosmetic agent) held inside the porous network of the microspheres.

  4. FORMULATION AND EVALUATION OF MUCOADHESIVE MICROSPHERES OF NIFEDIPINE

    Directory of Open Access Journals (Sweden)

    G.V. Radha

    2012-10-01

    Full Text Available In the present study, an attempt has been made to evaluate mucoadhesive microspheres of nifedipine by orifice ionic gelation method employing sodium alginate and different mucoadhesive polymers (HPMC, carbopol alone and in combination of different proportions. The compatibility study was done between drug and polymer by FTIR which shows no interaction between the drug and polymer. The prepared microspheres were evaluated for particle size ,angle of repose, carrs index, swelling index, microencapsulation efficiency, percent drug content, drug release, kinetics and mechanism of drug release. The microspheres were found discrete, spherical, free flowing and the particle size was found in the range of 765 to 792µ. The encapsulation efficiency was found in the range of 55 to 69 %. Percent drug content was found to be in the range of 96 to 99 %. All the microspheres showed good muco adhesive property in the in vitro wash off test. Drug release from the microspheres was found slow, followed first order kinetics with non fickian release mechanism and release dependent on nature and concentration of polymers.

  5. Making Polymeric Microspheres

    Science.gov (United States)

    Rhim, Won-Kyu; Hyson, Michael T.; Chung, Sang-Kun; Colvin, Michael S.; Chang, Manchium

    1989-01-01

    Combination of advanced techniques yields uniform particles for biomedical applications. Process combines ink-jet and irradiation/freeze-polymerization techniques to make polymeric microspheres of uniform size in diameters from 100 to 400 micrometer. Microspheres used in chromatography, cell sorting, cell labeling, and manufacture of pharmaceutical materials.

  6. Preparation of magnetic hierarchically porous microspheres with temperature-controlled wettability for removal of oils.

    Science.gov (United States)

    Tao, Shengyang; Ding, Yunzhe; Jiang, Lei; Li, Guangtao

    2017-04-15

    A series of monodispersed microspheres with hierarchically porous structures were prepared by microfluidic devices. Phase separation of the silica sol in microdroplets was adopted to construct these structures. The effects of velocity ratios (for both the continuous and the dispersed phases), collection solvents and calcination temperatures were investigated. The diameters of the microspheres were tuned from 148μm to 940μm by adjusting the velocity ratio. Tests revealed that the surface areas and pore volumes of the microspheres can reach 495m(2)g(-1) and 0.6068mlg(-1), respectively. The macroporous structure can be controlled by the collection solvents, and the wettability of the microspheres is determined by the calcination temperature. A calcination temperature of 450°C leads to a hydrophilic surface property. Fe3O4 nanoparticles were added to the silica sol to form magnetic microspheres, and the porous structure was not affected. This kind of hybrid microsphere adsorbs 3.29 times its own weight in toluene. These spheres can adsorb oil on water surfaces, and then be removed from the water with an external magnetic field. The microspheres can be recovered and reused more than 10 times. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Fabrication of Magnetic-Antimicrobial-Fluorescent Multifunctional Hybrid Microspheres and Their Properties

    Directory of Open Access Journals (Sweden)

    Ling-Han Xiao

    2013-04-01

    Full Text Available Novel magnetic-antimicrobial-fluorescent multifunctional hybrid microspheres with well-defined nanostructure were synthesized by the aid of a poly(glycidyl methacrylate (PGMA template. The hybrid microspheres were fully characterized by scanning electron microscopy (SEM, transmission electron microscopy (TEM, Fourier transform infrared (FTIR, X-ray diffraction (XRD and digital fluorescence microscope. The as-synthesized microspheres PGMA, amino-modified PGMA (NH2-PGMA and magnetic PGMA (M-PGMA have a spherical shape with a smooth surface and fine monodispersity. M-PGMA microspheres are super-paramagnetic, and their saturated magnetic field is 4.608 emu·g−1, which made M-PGMA efficiently separable from aqueous solution by an external magnetic field. After poly(haxemethylene guanidine hydrochloride (PHGH functionalization, the resultant microspheres exhibit excellent antibacterial performance against both Gram-positive and Gram-negative bacteria. The fluorescence feature originating from the quantum dot CdTe endowed the hybrid microspheres with biological functions, such as targeted localization and biological monitoring functions. Combination of magnetism, antibiosis and fluorescence into one single hybrid microsphere opens up the possibility of the extensive study of multifunctional materials and widens the potential applications.

  8. Optimization of sustained release aceclofenac microspheres using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Deshmukh, Rameshwar K.; Naik, Jitendra B., E-mail: jitunaik@gmail.com

    2015-03-01

    Polymeric microspheres containing aceclofenac were prepared by single emulsion (oil-in-water) solvent evaporation method using response surface methodology (RSM). Microspheres were prepared by changing formulation variables such as the amount of Eudragit® RS100 and the amount of polyvinyl alcohol (PVA) by statistical experimental design in order to enhance the encapsulation efficiency (E.E.) of the microspheres. The resultant microspheres were evaluated for their size, morphology, E.E., and in vitro drug release. The amount of Eudragit® RS100 and the amount of PVA were found to be significant factors respectively for determining the E.E. of the microspheres. A linear mathematical model equation fitted to the data was used to predict the E.E. in the optimal region. Optimized formulation of microspheres was prepared using optimal process variables setting in order to evaluate the optimization capability of the models generated according to IV-optimal design. The microspheres showed high E.E. (74.14 ± 0.015% to 85.34 ± 0.011%) and suitably sustained drug release (minimum; 40% to 60%; maximum) over a period of 12 h. The optimized microspheres formulation showed E.E. of 84.87 ± 0.005 with small error value (1.39). The low magnitudes of error and the significant value of R{sup 2} in the present investigation prove the high prognostic ability of the design. The absence of interactions between drug and polymers was confirmed by Fourier transform infrared (FTIR) spectroscopy. Differential scanning calorimetry (DSC) and X-ray powder diffractometry (XRPD) revealed the dispersion of drug within microspheres formulation. The microspheres were found to be discrete, spherical with smooth surface. The results demonstrate that these microspheres could be promising delivery system to sustain the drug release and improve the E.E. thus prolong drug action and achieve the highest healing effect with minimal gastrointestinal side effects. - Highlights: • Aceclofenac microspheres

  9. Preparation of polystyrene microspheres for laser velocimetry in wind tunnels

    Science.gov (United States)

    Nichols, Cecil E., Jr.

    1987-01-01

    Laser Velocimetry (L/V) had made great strides in replacing intrusive devices for wind tunnel flow measurements. The weakness of the L/V has not been the L/V itself, but proper size seeding particles having known drag characteristics. For many Langley Wind Tunnel applications commercial polystyrene latex microspheres suspended in ethanol, injected through a fluid nozzle provides excellent seeding but was not used due to the high cost. This paper provides the instructions, procedures, and formulations for producing polystyrene latex monodisperse microspheres of 0.6, 1.0, 1.7, 2.0, and 2.7 micron diameters. These are presently being used at Langley Research Center as L/V seeding particles.

  10. Unstirred Water Layer Effects on Biodegradable Microspheres

    Directory of Open Access Journals (Sweden)

    Susan D’Souza

    2015-01-01

    Full Text Available This study explores the mechanistic aspects of in vitro release from biodegradable microspheres with the objective of understanding the effect of the unstirred water layer on polymer degradation and drug release. In vitro drug release experiments on Leuprolide PLGA microspheres were performed under “static” and “continuous” agitation conditions using the “sample and separate” method. At specified time intervals, polymer degradation, mass loss, and drug release were assessed. While molecular weight and molecular number profiles for “static” and “continuous” samples were indistinct, mass loss occurred at a faster rate in “continuous” samples than under “static” conditions. In vitro results describe a fourfold difference in drug release rates between the “continuous” and “static” samples, ascribed to the acceleration of various processes governing release, including elimination of the boundary layer. The findings were confirmed by the fourfold increase in drug release rate when “static” samples were subjected to “continuous” agitation after 11 days. A schema was proposed to describe the complex in vitro release process from biodegradable polymer-drug dosage forms. These experiments highlight the manner in which the unstirred water layer influences drug release from biodegradable microspheres and stress the importance of selecting appropriate conditions for agitation during an in vitro release study.

  11. Polymeric Microspheres for Medical Applications

    Directory of Open Access Journals (Sweden)

    Ketie Saralidze

    2010-06-01

    Full Text Available Synthetic polymeric microspheres find application in a wide range of medical applications. Among other applications, microspheres are being used as bulking agents, embolic- or drug-delivery particles. The exact composition of the spheres varies with the application and therefore a large array of materials has been used to produce microspheres. In this review, the relation between microsphere synthesis and application is discussed for a number of microspheres that are used for different treatment strategies.

  12. INVESTIGATION OF DRUG RELEASE FROM BIODEGRADABLE PLG MICROSPHERES: EXPERIMENT AND THEORY

    Energy Technology Data Exchange (ETDEWEB)

    ANDREWS, MALCOLM J. [Los Alamos National Laboratory; BERCHANE, NADER S. [Los Alamos National Laboratory; CARSON, KENNETH H. [Los Alamos National Laboratory; RICE-FICHT, ALLISON C. [Los Alamos National Laboratory

    2007-01-30

    Piroxicam containing PLG microspheres having different size distributions were fabricated, and in vitro release kinetics were determined for each preparation. Based on the experimental results, a suitable mathematical theory has been developed that incorporates the effect of microsphere size distribution and polymer degradation on drug release. We show from in vitro release experiments that microsphere size has a significant effect on drug release rate. The initial release rate decreased with an increase in microsphere size. In addition, the release profile changed from first order to concave-upward (sigmoidal) as the system size was increased. The mathematical model gave a good fit to the experimental release data.

  13. Yielding behavior and temperature-induced on-field oscillatory rheological studies in a novel MR suspension containing polymer-capped Fe3Ni alloy microspheres

    Science.gov (United States)

    Arief, Injamamul; Mukhopadhyay, P. K.

    2017-05-01

    Magnetic Bimetallic alloy nanoparticles of 3d elements are known for their tunable shape, size and magnetic anisotropy and find extensive applications ranging from magneto-mechanical to biomedical devices. This paper reports the polyol-mediated synthesis of Fe-rich polyacrylic acid (PAA)-Fe3Ni alloyed microspheres and its morphological and structural characterizations with scanning electron microscopy and X-ray diffraction studies. Magnetorheological fluid was prepared by dispersing the 10 vol% microparticles in silicone oil. The room temperature viscoelastic characterization of the fluid was performed under different magnetic fields. The field-dependent yield stresses were scaled using Klingenberg model and found that static yield stress was more accurately described by an M3 dependence, where M is particle magnetization. We proposed a multipolar contribution and ascertained the fact that simple dipolar description was insufficient to describe the trend in a complex rheological fluid. Temperature-dependent oscillatory rheological studies under various fields were also investigated. This demonstrated a strong temperature-induced thinning effect. The temperature-thinning in complex moduli and viscosity were more pronounced for the samples at higher magnetic field owing to quasi-solid behavior.

  14. Insulin delivery through nasal route using thiolated microspheres.

    Science.gov (United States)

    Nema, Tarang; Jain, Ashish; Jain, Aviral; Shilpi, Satish; Gulbake, Arvind; Hurkat, Pooja; Jain, Sanjay K

    2013-01-01

    The aim of the present study was to investigate the potential of developed thiolated microspheres for insulin delivery through nasal route. In the present study, cysteine was immobilized on carbopol using EDAC. A total of 269.93 µmol free thiol groups per gram polymer were determined. The prepared nonthiolated and thiolated microspheres were studied for particle shape, size, drug content, swellability, mucoadhesion and in vitro insulin release. The thiolated microspheres exhibited higher mucoadhesion due to formation of covalent bonds via disulfide bridges with the mucus gel layer. Drug permeation through goat nasal mucosa of nonthiolated and thiolated microspheres were found as 52.62 ± 2.4% and 78.85 ± 3.1% in 6 h, respectively. Thiolated microspheres bearing insulin showed better reduction in blood glucose level (BGL) in comparison to nonthiolated microspheres as 31.23 ± 2.12% and 75.25 ± 0.93% blood glucose of initial BGL were observed at 6 h after nasal delivery of thiolated and nonthiolated microspheres in streptozotocin-induced diabetic rabbits.

  15. PREPARATION AND CHARACTERIZATION OF TRAMADOL HYDROCHLORIDE MICROSPHERES

    Directory of Open Access Journals (Sweden)

    Patel Keyur

    2015-10-01

    Full Text Available Tramadol HCl was microencapsulated with Ethylcellulose using multiple emulsion solvent evaporation method. A 32 factorial design employed to study the effect of drug: polymer ratio and volume of External phase (1% PVA on % yield, % encapsulation efficiency, particle size, % drug release rate. The drug: polymer ratio and volume of continuous phase were significant effect on % yield, % entrapment efficiency, particle size, % drug release rate. % drug release was Biphasic system first initially bursting effect and finally sustained. Higher Percentage yield (77.4% and Higher Percentage Encapsulation Efficiency(31.1% were observed in Batch EC3. All the microspheres were spherical in nature its surface was smooth observed in SEM report.

  16. Processing and Characterization of Sol-Gel Cerium Oxide Microspheres

    Energy Technology Data Exchange (ETDEWEB)

    McClure, Zachary D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Padilla Cintron, Cristina [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-09-27

    Of interest to space exploration and power generation, Radioisotope Thermoelectric Generators (RTGs) can provide long-term power to remote electronic systems without the need for refueling or replacement. Plutonium-238 (Pu-238) remains one of the more promising materials for thermoelectric power generation due to its high power density, long half-life, and low gamma emissions. Traditional methods for processing Pu-238 include ball milling irregular precipitated powders before pressing and sintering into a dense pellet. The resulting submicron particulates of Pu-238 quickly accumulate and contaminate glove boxes. An alternative and dust-free method for Pu-238 processing is internal gelation via sol-gel techniques. Sol-gel methodology creates monodisperse and uniform microspheres that can be packed and pressed into a pellet. For this study cerium oxide microspheres were produced as a surrogate to Pu-238. The similar electronic orbitals between cerium and plutonium make cerium an ideal choice for non-radioactive work. Before the microspheres can be sintered and pressed they must be washed to remove the processing oil and any unreacted substituents. An investigation was performed on the washing step to find an appropriate wash solution that reduced waste and flammable risk. Cerium oxide microspheres were processed, washed, and characterized to determine the effectiveness of the new wash solution.

  17. Ketoprofen-loaded Eudragit RSPO microspheres: an influence of sodium carbonate on in vitro drug release and surface topology.

    Science.gov (United States)

    Pandit, Sachin S; Hase, Dinesh P; Bankar, Manish M; Patil, Arun T; Gaikwad, Naresh J

    2009-05-01

    Eudragit RSPO microspheres containing ketoprofen as model drug, prepared by solvent evaporation technique using acetone-liquid paraffin (heavy) solvent system were examined. Depending upon polymer concentration in the internal phase, microspheres of particle mean diameter (122.8, 213.6 and 309.5 μm) were obtained. The influence of surface washing of microspheres with n-hexane, i.e. untreated microspheres (UM) on the drug content, drug release and surface topology of microspheres were compared to those of microspheres washed with sodium carbonate, i.e. treated microspheres (TM) in order to make the non-encapsulated surface drug soluble. The significant reduction in encapsulation efficiency (p removes a significant amount of drug (p microsphere polymer matrix. Scanning electron microscopy (SEM) examination revealed that the removal of surface drug did not affect the size of microspheres but the topology of treated smallest microspheres was modified. The ketoprofen release profiles were examined in phosphate buffer pH 7.4, using USPXXIII paddle type dissolution apparatus. In general both UM and TM result in biphasic release patterns, but the initial burst effect (first release phase) of TM was lower than that of UM. The second release phase did not change for the bigger size but increased for the smallest microspheres, probably owing to the modification of matrix porosity.

  18. Synthesis of PGMA Microspheres with Amino Groups for High-capacity Adsorption of Cr(VI) by Cerium Initiated Graft Polymerizatio

    Institute of Scientific and Technical Information of China (English)

    李鹏飞; 杨良嵘; 何秀琼; 王娟; 孔鹏; 邢慧芳; 刘会洲

    2012-01-01

    Abstract A novel polyglycidylmethacrylate (PGMA) microspheres with high adsorption capacity of Cr(VI) was prepared by cerium(IV) initiated graft polymerization of tentacle-type polymer chains with amino group on polymer microspheres with hydroxyl groups. The micron-sized PGMA microspheres were prepared by a dispersion polym erization method and subsequently modified by ring-opening reaction to introduce functional hydroxyl groups. The polymer microspheres were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results indicated that the polymer microspheres had an average diameter of 5 m with uniform size distribution. The free amino group content was determined to be 5.13 mmol·g^-1 for g;PGMA-NH2 microspheres by potentiometric and conductometric titration methods. The Cr(VI) adsorption results indicated that the graft polymerization of tentacle-type polymer chains on the polymer microspheres could produce adsorbents with high adsorption capacity (500 mg-g-l). The polymer microspheres with grafted tentacle polymer chains have potenial application in large-scale removal of Cr(VI) in aqueous solution.

  19. MONODISPERSED AND NANOSIZED DENDRIMER/POLYSTYRENE LATEX PARTICLES

    Institute of Scientific and Technical Information of China (English)

    Changfeng Yi; Zushun Xu; Warren T. Ford

    2004-01-01

    Emulsion polymerization of styrene was carried out using dendrimer DAB-dendr-(NH2)64 as seed. The size and size distribution of the emulsion particles were characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS), and the effects of emulsion polymerization conditions on the preparation of emulsion particle were investigated. It has been found that the nanosized dendrimer/polystyrene polymer emulsion particles obtained were in the range of 26~64 nm in diameter, and were monodisperse; the size and size distribution of emulsion particles were influenced by the contents of dendrimer DAB-dendr-(NH2)64, emulsifier and initiator, as well as the pH value.

  20. Facile preparation of multifunctional superparamagnetic PHBV microspheres containing SPIONs for biomedical applications

    Science.gov (United States)

    Li, Wei; Jan Zaloga; Ding, Yaping; Liu, Yufang; Janko, Christina; Pischetsrieder, Monika; Alexiou, Christoph; Boccaccini, Aldo R.

    2016-03-01

    The promising potential of magnetic polymer microspheres in various biomedical applications has been frequently reported. However, the surface hydrophilicity of superparamagnetic iron oxide nanoparticles (SPIONs) usually leads to poor or even failed encapsulation of SPIONs in hydrophobic polymer microspheres using the emulsion method. In this study, the stability of SPIONs in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) solution was significantly increased after surface modification with lauric acid. As a result, magnetic PHBV microspheres with high encapsulation efficiencies (71.0-87.4%) were prepared using emulsion-solvent extraction/evaporation method. Magnetic resonance imaging (MRI) showed significant contrast for the magnetic PHBV microspheres. The toxicity of these magnetic PHBV microspheres towards human T-lymphoma suspension cells and adherent colon carcinoma HT-29 cells was investigated using flow cytometry, and they were shown to be non-toxic in a broad concentration range. A model drug, tetracycline hydrochloride, was used to demonstrate the drug delivery capability and to investigate the drug release behavior of the magnetic PHBV microspheres. The drug was successfully loaded into the microspheres using lauric acid-coated SPIONs as drug carrier, and was released from the microspheres in a diffusion controlled manner. The developed magnetic PHBV microspheres are promising candidates for biomedical applications such as targeted drug delivery and MRI.

  1. Microsphere Insulation Panels

    Science.gov (United States)

    Mohling, R.; Allen, M.; Baumgartner, R.

    2006-01-01

    Microsphere insulation panels (MIPs) have been developed as lightweight, longlasting replacements for the foam and vacuum-jacketed systems heretofore used for thermally insulating cryogenic vessels and transfer ducts. The microsphere core material of a typical MIP consists of hollow glass bubbles, which have a combination of advantageous mechanical, chemical, and thermal-insulation properties heretofore available only separately in different materials. In particular, a core filling of glass microspheres has high crush strength and low density, is noncombustible, and performs well in soft vacuum.

  2. Formulation and evalution of montelukast sodium - chitosan based spray dried microspheres for pulmonary drug delivery

    Directory of Open Access Journals (Sweden)

    Rushi Panchal

    2012-01-01

    Full Text Available The objective of present work was to prepare microspheres of montelukast sodium using a natural polymer- chitosan by spray drying method by using glutaraldehyde as a cross linking agent. The microspheres were characterized for size, shape, dissolution, swelling and mucoadhesion. It was observed that, all microspheres were spherical in shape with narrow size distribution. Microspheres had mean particle size of 7-12 μm, with % encapsulation efficiency of 78-86%. The % yield was 32-49% and drug load was 48-53%. With the increase in proportion of chitosan in formulation mucoadhesive strength was increase and also increased in particle size of microspheres. As the drug:polymer ratio increase drug loading was increase and % encapsulation efficiency was also increase.

  3. Novel Au/La-SrTiO3 microspheres: superimposed effect of gold nanoparticles and lanthanum doping in photocatalysis.

    Science.gov (United States)

    Wang, Guannan; Wang, Pei; Luo, He-Kuan; Hor, T S Andy

    2014-07-01

    Novel multielement Au/La-SrTiO(3) microspheres were synthesized by a solvothermal method using monodisperse gold and La-SrTiO(3) nanocrystals as building blocks. The porous Au/La-SrTiO(3) microspheres had a large surface area of 94.6 m(2)  g(-1). The stable confined Au nanoparticles demonstrated strong surface plasmon resonance effect, leading to enhanced absorption in a broad UV/Vis/NIR range. Doping of rare-earth metal La also broadened the absorption band to the visible region. Both the conduction and valence bands of Au/La-SrTiO(3) microspheres thus show favorable potential for proton reduction under visible light. The superimposed effect of Au nanoparticles and La doping in Au/La-SrTiO(3) microspheres led to high photocurrent density in photoelectrochemical water splitting and good photocatalytic activity in photodegradation of rhodamine B. The photocatalytic activities are in the order of the following: Au/La-SrTiO(3) microspheres>Au/SrTiO(3) microspheres>La-SrTiO(3) microspheres>SrTiO(3) microspheres.

  4. A Novel Polymer-Synthesized Ceramic Composite Based System for Bone Repair: Osteoblast Growth on Scaffolds with Varied Calcium Phosphate Content

    Science.gov (United States)

    2005-01-01

    demongtrated the synthesis of degradable scaffolds from PLAGA /calcium phosphate composite microspheres in which an amorphous calcium phosphate is...EXPERIMENTAL DETAILS Scaffold Preparation Scaffolds were prepared as described in detail previously [3]. Briefly, PLAGA /calcium phosphate composite...culture polystyrene (TCPS) 2- pure PLAGA microspheres 64 3- composite microsphere matrices with a low polymer/ceramic ratio 4- composite microsphere

  5. Organic aerogel microspheres

    Science.gov (United States)

    Mayer, Steven T.; Kong, Fung-Ming; Pekala, Richard W.; Kaschmitter, James L.

    1999-01-01

    Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  6. Organic aerogel microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, S.T.; Kong, F.M.; Pekala, R.W.; Kaschmitter, J.L.

    1999-06-01

    Organic aerogel microspheres are disclosed which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonstick gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  7. Nanomechanical properties of multi-block copolymer microspheres for drug delivery applications.

    Science.gov (United States)

    Moshtagh, P R; Rauker, J; Sandker, M J; Zuiddam, M R; Dirne, F W A; Klijnstra, E; Duque, L; Steendam, R; Weinans, H; Zadpoor, A A

    2014-06-01

    Biodegradable polymeric microspheres are interesting drug delivery vehicles for site-specific sustained release of drugs used in treatment of osteoarthritis. We study the nano-mechanical properties of microspheres composed of hydrophilic multi-block copolymers, because the release profile of the microspheres may be dependent on the mechanical interactions between the host tissues and the microspheres that aim to incorporate between the cartilage surfaces. Three different sizes of monodisperse microspheres, namely 5, 15, and 30μm, were tested in both dry and hydrated (swollen) states. Atomic force microscopy was used for measuring nanoindentation-based force-displacement curves that were later used for calculating the Young׳s moduli using the Hertz׳s contact theory. For every microsphere size and condition, the measurements were repeated 400-500 times at different surface locations and the histograms of the Young׳s modulus were plotted. The mean Young׳s modulus of 5, 15, and 30μm microspheres were respectively 56.1±71.1 (mean±SD), 94.6±103.4, and 57.6±58.6MPa under dry conditions and 226.4±54.2, 334.5±128.7, and 342.5±136.8kPa in the swollen state. The histograms were not represented well by the average Young׳s modulus and showed three distinct peaks in the dry state and one distinct peak in the swollen state. The peaks under dry conditions are associated with the different parts of the co-polymeric material at the nano-scale. The measured mechanical properties of swollen microspheres are within the range of the nano-scale properties of cartilage, which could favor integration of the microspheres with the host tissue.

  8. Preparation, characterization and in vitro release study of BSA-loaded double-walled glucose-poly(lactide-co-glycolide) microspheres.

    Science.gov (United States)

    Ansary, Rezaul H; Rahman, Mokhlesur M; Awang, Mohamed B; Katas, Haliza; Hadi, Hazrina; Mohamed, Farahidah; Doolaanea, Abd Almonem; Kamaruzzaman, Yunus B

    2016-09-01

    The aim of this study was to prepare a model protein, bovine serum albumin (BSA) loaded double-walled microspheres using a fast degrading glucose core, hydroxyl-terminated poly(lactide-co-glycolide) (Glu-PLGA) and a moderate-degrading carboxyl-terminated PLGA polymers to reduce the initial burst release and to eliminate the lag phase from the release profile of PLGA microspheres. The double-walled microspheres were prepared using a modified water-in-oil-in-oil-in-water (w/o/o/w) method and single-polymer microspheres were prepared using a conventional water-in-oil-in-water (w/o/w) emulsion solvent evaporation method. The particle size, morphology, encapsulation efficiency, thermal properties, in vitro drug release and structural integrity of BSA were evaluated in this study. Double-walled microspheres prepared with Glu-PLGA and PLGA polymers with a mass ratio of 1:1 were non-porous, smooth-surfaced, and spherical in shape. A significant reduction of initial burst release was achieved for the double-walled microspheres compared to single-polymer microspheres. In addition, microspheres prepared using Glu-PLGA and PLGA polymers in a mass ratio of 1:1 exhibited continuous BSA release after the small initial burst without any lag phase. It can be concluded that the double-walled microspheres made of Glu-PLGA and PLGA polymers in a mass ratio of 1:1 can be a potential delivery system for pharmaceutical proteins.

  9. Effect of water phase additives on particle structure and expansion behavior of thermal-expandable polymer microspheres%水相添加剂对热可膨胀聚合物微球颗粒结构和膨胀特性的影响

    Institute of Scientific and Technical Information of China (English)

    谢贵明; 王稚阳; 包永忠

    2015-01-01

    Thermal-expandable polymer microspheres with core-shell structure were synthesized by suspension copolymerization of vinylidene chloride-acrylonitrile-methyl methacrylate (VDC-AN-MMA) in the presence of pentane as a foaming agent. The influence of water phase additives, such as sodium chloride, citric acid and potassium dichromate, on the particle structure and thermal expansion properties of polymer microspheres were investigated. The results showed that the additions of sodium chloride, citric acid and potassium dichromate could significantly reduce the number of un-expandable fine polymer particles. To be specific, when the loading of sodium chloride, citric acid and potassium dichromate was 4%, 2.5%—5.0% and 0.05%—0.1% (based on monomers), respectively, the prepared expandable microspheres exhibited narrow particle size distributions, regular morphology and good encapsulation of foaming agent by polymer. Few particles were unexpanded and the expansion of particles was uniform after the heat treating of the microspheres.%通过戊烷发泡剂存在下的偏氯乙烯-丙烯腈-甲基丙烯酸甲酯(VDC-AN-MMA)悬浮共聚制备包覆型热可膨胀聚合物微球,考察氯化钠、柠檬酸和重铬酸钾等水相添加剂对聚合物微球颗粒结构和热膨胀特性的影响。结果表明氯化钠、柠檬酸和重铬酸钾的添加均可起到降低聚合过程中形成难膨胀聚合物细微粒子的作用,当氯化钠添加量为4%(质量分数,基于单体,下同)、柠檬酸添加量为2.5%~5.0%、重铬酸钾添加量为0.05%~0.1%时,制备的可膨胀聚合物微球具有粒径分布窄、形态规整、聚合物对发泡剂包覆效果好等特点;加热后未膨胀聚合物微粒数目少,膨胀均匀,膨胀温度区间宽。

  10. PLGA and PHBV Microsphere Formulations and Solid-State Characterization

    DEFF Research Database (Denmark)

    Yang, Chiming; Plackett, David; Needham, David

    2009-01-01

    To develop and characterize the solid-state properties of poly(DL-lactic-co-glycolic acid) (PLGA) and poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV) microspheres for the localized and controlled release of fusidic acid (FA). The effects of FA loading and polymer composition on the mean...

  11. Fabrication of CeO2 by sol-gel process based on microfluidic technology as an analog preparation of ceramic nuclear fuel microspheres

    CERN Document Server

    Ye, Bin; Li, Jiaolong; Zhao, Zichen; Chang, Zhenqi; Serra, Christophe A

    2012-01-01

    Microfluidics integrated with sol-gel processes is introduced in preparing monodispersed MOX nuclear fuel microspheres using nonactive cerium as a surrogate for uranium or plutonium. The detailed information about microfluidic devices and sol-gel processes are provided. The effects of viscosity and flow rate of continuous and dispersed phase on size and size distribution of CeO2 microspheres have been investigated. A comprehensive characterization of the CeO2 microspheres has been conducted, including XRD pattern, SEM, density, size and size distribution. The size of prepared monodisperse particles can be controlled precisely in range of 10{\\mu}m to 1000{\\mu}m and the particle CV is below 3%.

  12. Preparation and properties of BSA-loaded microspheres based on multi-(amino acid) copolymer for protein delivery.

    Science.gov (United States)

    Chen, Xingtao; Lv, Guoyu; Zhang, Jue; Tang, Songchao; Yan, Yonggang; Wu, Zhaoying; Su, Jiacan; Wei, Jie

    2014-01-01

    A multi-(amino acid) copolymer (MAC) based on ω-aminocaproic acid, γ-aminobutyric acid, L-alanine, L-lysine, L-glutamate, and hydroxyproline was synthetized, and MAC microspheres encapsulating bovine serum albumin (BSA) were prepared by a double-emulsion solvent extraction method. The experimental results show that various preparation parameters including surfactant ratio of Tween 80 to Span 80, surfactant concentration, benzyl alcohol in the external water phase, and polymer concentration had obvious effects on the particle size, morphology, and encapsulation efficiency of the BSA-loaded microspheres. The sizes of BSA-loaded microspheres ranged from 60.2 μm to 79.7 μm, showing different degrees of porous structure. The encapsulation efficiency of BSA-loaded microspheres also ranged from 38.8% to 50.8%. BSA release from microspheres showed the classic biphasic profile, which was governed by diffusion and polymer erosion. The initial burst release of BSA from microspheres at the first week followed by constant slow release for the next 7 weeks were observed. BSA-loaded microspheres could degrade gradually in phosphate buffered saline buffer with pH value maintained at around 7.1 during 8 weeks incubation, suggesting that microsphere degradation did not cause a dramatic pH drop in phosphate buffered saline buffer because no acidic degradation products were released from the microspheres. Therefore, the MAC microspheres might have great potential as carriers for protein delivery.

  13. [Prolonged release of chlorambucil and etoposide from poly-3-oxybutyrate-based microspheres].

    Science.gov (United States)

    Filatova, E V; Iakovlev, S G; Bonartsev, A P; Makhina, T K; Myshkina, V L; Bonartseva, G A

    2012-01-01

    Microspheres were obtained on the basis of poly(3-oxibutyrate) (POB) with the inclusion of the Chlorambucil and Etoposide cytostatic drugs in a polymer matrix, and the morphology, kinetics of drug release from microspheres, and the interaction between microspheres and tumor cells in vitro were studied. Data on the kinetics of drug release suggests that a prolonged release occurs by drug diffusion from the polymer matrix at the initial stage and at the expense of hydrolytic degradation of the polymer at a later stage. A study of the biocompatibility and biological activity of biopolymeric microspheres showed that chlorambucil operates actively and strongly inhibits the growth of cultured cells for a short time (24 h). Etoposide acts weaker (the percentage of cell growth suppression during 48 h does not exceed 50%), but subsequently it has a basis for the creation of new dosage forms with prolonged action of Etoposide and chlorambucil for cancer therapy.

  14. Development and evaluation of biodegradable microspheres embedded in in situ gel for controlled delivery of hydrophilic drug for treating oral infections: In vitro and in vivo studies

    Directory of Open Access Journals (Sweden)

    Neha Manish Munot

    2014-01-01

    Full Text Available Present investigation was aimed at developing biodegradable polymeric microspheres of Tetracycline hydrochloride to treat oral infections by using Poly (D, L lactic-co-glycolic acid (50:50 as polymer. Microspheres were prepared using oil-in-oil (O/O and water-in-oil-in-water (W/O/W double emulsion solvent evaporation method. Microspheres prepared by W/O/W were spherical in shape compared those prepared with O/O method. Thus, the microspheres formulated by W/O/W method were further evaluated for particle size, morphology, entrapment efficiency, and percent drug release. Effects of salt addition, polymer concentration on the characteristics of microspheres and tetracycline release profile were investigated. An increase in polymer concentration decreased drug release and increased entrapment efficiency of drug. In vitro studies indicated that release of drug from microspheres could be controlled for 10-15 days depending on drug: Polymer concentration. Formulation E released 99.10% of drug from microspheres in 10 days. Addition of sodium chloride to outer aqueous phase produced spherical microspheres with smooth surface and also increased entrapment efficiency. Microspheres were further dispersed in optimized formulation of mucoadhesive in situ gel of Pluronic F127, which acts as carrier for microspheres. In vivo studies were conducted on patients who underwent molar tooth extraction to check efficacy of designed formulation.

  15. Preparation and in vitro dissolution profile of zidovudine loaded microspheres made of Eudragit RS 100, RL 100 and their combinations.

    Science.gov (United States)

    Nath, Bipul; Nath, Lila Kanta; Kumar, Pradeep

    2011-01-01

    The objective of present investigation was to evaluate the entrapment efficiency of the anti-HIV drug, zidovudine, using two Eudragit polymers of different permeability characteristics and to study the effect of this entrapment on the drug release properties. In order to increase the entrapment efficiency optimum concentration of polymer solutions were prepared in acetone using magnesium stearate as droplet stabilizer. The morphology of the microspheres was evaluated using a scanning electron microscope, which showed a spherical shape with smooth surface. The mean sphere diameter was between 1000-3000 microm and the entrapment efficiencies ranged from 56.4-87.1%. Polymers were used separately and in combination to prepare different microspheres. The prepared microspheres were studied for drug release behavior in phosphate buffer at pH 7.4, because the Eudragit polymers are independent of the pH of the dissolution medium. The release profiles and entrapment efficiencies depended strongly on the structure of the polymers used as wall materials. The release rate of zidovudine from Eudragit RS 100 microspheres was much lower than that from Eudragit RL 100 microspheres. Evaluation of release data reveals that release of zidovudine from Eudragit RL 100 microspheres followed the Higuchi rule, whereas Eudragit RS 100 microspheres exhibited an initial burst release, a lag period for entry of surrounding dissolution medium into polymer matrix and finally, diffusion of drug through the wall material.

  16. Study of mucoadhesive microsphere of pirfenidone for nasal drug delivery

    Directory of Open Access Journals (Sweden)

    Vrushali Kashikar

    2014-01-01

    Full Text Available The present research work involves formulation development and evaluation of nasal mucoadhesive microsphere in view to, improve bioavailability and reduce dosing regimen. Microspheres were prepared by spray drying and cross-linking method using chitosan and HPMC K4M, using 32 central composite design. Microspheres were evaluated for particle size, drug content, swelling ability, and percentage yield. Compatibility was checked by doing Fourier transform infrared spectroscopy and Differential scanning calorimetry study. The polymorphism and particle shape were studied by X-ray diffraction and scanning electron microscopy. The average particle size of spray-dried and cross-linked formulations were found in the range between 20-50 μm and 30-60 μm with percent mucoadhesion in the range of 80%-90% and 60-70%, respectively. In vitro drug release was found to be proportional to drug to polymer ratio. In vitro drug release for optimized formulation, that is, (F1, for spray-drying method and cross-linking method was found to be 88.73% and 70.93% at the end of 6 h, respectively. Release of drug from microspheres followed non-Fickian diffusion kinetics. Ex vivo studies were performed with sheep nasal mucosa for mucoadhesion, histopathological study, and drug permeation. The histopathological study indicates nonirritant nature of microsphere. The microspheres were found to be stable at accelerated storage conditions for 1 month, as per International Conference of Harmonisation guidelines.

  17. Mucoadhesive microspheres prepared by interpolymer complexation and solvent diffusion method.

    Science.gov (United States)

    Chun, Myung-Kwan; Cho, Chong-Su; Choi, Hoo-Kyun

    2005-01-20

    Mucoadhesive microspheres were prepared to increase gastric residence time using an interpolymer complexation of poly(acrylic acid) (PAA) with poly(vinyl pyrrolidone) (PVP) and a solvent diffusion method. The complexation between poly(acrylic acid) and poly(vinyl pyrrolidone) as a result of hydrogen bonding was confirmed by the shift in the carbonyl absorption bands of poly(acrylic acid) using FT-IR. A mixture of ethanol/water was used as the internal phase, corn oil was used as the external phase of emulsion, and span 80 was used as the surfactant. Spherical microspheres were prepared and the inside of the microspheres was completely filled. The optimum solvent ratio of the internal phase (ethanol/water) was 8/2 and 7/3, and the particle size increased as the content of water was increased. The mean particle size increased with the increase in polymer concentration. The adhesive force of microspheres was equivalent to that of Carbopol. The release rate of acetaminophen from the complex microspheres was slower than the PVP microspheres at pH 2.0 and 6.8.

  18. In situ Gelation of Monodisperse Alginate Hydrogel in Microfluidic Channel Based on Mass Transfer of Calcium Ions

    Energy Technology Data Exchange (ETDEWEB)

    Song, YoungShin; Lee, Chang-Soo [Chungnam National University, Daejeon (Korea, Republic of)

    2014-10-15

    A microfluidic method for the in situ production of monodispersed alginate hydrogels using biocompatible polymer gelation by crosslinker mass transfer is described. Gelation of the hydrogel was achieved in situ by the dispersed calcium ion in the microfluidic device. The capillary number (Ca) and the flow rate of the disperse phase which are important operating parameters mainly influenced the formation of three distinctive flow regions, such as dripping, jetting, and unstable dripping. Under the formation of dripping region, monodispersed alginate hydrogels having a narrow size distribution (C.V=2.71%) were produced in the microfluidic device and the size of the hydrogels, ranging from 30 to 60 µm, could be easily controlled by varying the flow rate, viscosity, and interfacial tension. This simple microfluidic method for the production of monodisperse alginate hydrogels shows strong potential for use in delivery systems of foods, cosmetics, inks, and drugs, and spherical alginate hydrogels which have biocompatibility will be applied to cell transplantation.

  19. Design and Characterization of Colon Targeted Tegaserod Microspheres by Ionotropic Gelation.

    Directory of Open Access Journals (Sweden)

    Nemade M. S.

    2015-11-01

    Full Text Available The aim of study was to develop and evaluate tegaserod maleate (TM microspheres for colonic drug delivery system. Microspheres of TM were prepared by with little modification in the ionotropic gelation method by using polymer tamarind seed polysaccharide (TSP. These microspheres were evaluated for angle of repose, bulk density, tapped density, particle size, percentage drug entrapment, swelling behavior and in-vitro drug release studies. All the micrometric properties of the microsphere were within the range. The mean particle size of prepared microspheres was found to be in a range of 715.66 - 747.00 μm. Percentage drug entrapment observed in all formulations was between 74.03 - 76.69 %. The % water uptake in the pH 1.2 and pH 7.8 was between 69.66 - 73.33 and 181 - 192 respectively. In-vitro drug release studies showed that the release of tegaserod maleate from the microspheres was mainly influenced by the polymer concentration. Among all the formulations, F1 and F3 shows 94.98 and 88.52% better controlled release at the end of 12 hr respectively. The results indicated that a decrease in release of the drug was observed by increasing the polymer concentration. It is concluded from the present investigation that TM loaded microspheres were promising controlled release carriers for colon targeted delivery.

  20. Preparation, characterization, and in vitro release of gentamicin from coralline hydroxyapatite-alginate composite microspheres.

    Science.gov (United States)

    Sivakumar, M; Rao, K Panduranga

    2003-05-01

    In this work, composite microspheres were prepared from bioactive ceramics such as coralline hydroxyapatite [Ca(10)(PO(4))(6)(OH)(2)] granules, a biodegradable polymer, sodium alginate, and an antibiotic, gentamicin. Previously, we have shown a gentamicin release from coralline hydroxyapatite granules-chitosan composite microspheres. In the present investigation, we attempted to prepare composite microspheres containing coralline hydroxyapatite granules and sodium alginate by the dispersion polymerization technique with gentamicin incorporated by absorption method. The crystal structure of the composite microspheres was analyzed using X-ray powder diffractometer. Fourier transform infrared spectra clearly indicated the presence of per-acid of sodium alginate, phosphate, and hydroxyl groups in the composite microspheres. Scanning electron micrographs and optical micrographs showed that the composite microspheres were spherical in shape and porous in nature. The particle size of composite microspheres was analyzed, and the average size was found to be 15 microns. The thermal behavior of composite microspheres was studied using thermogravimetric analysis and differential scanning calorimetric analysis. The cumulative in vitro release profile of gentamicin from composite microspheres showed near zero order patterns.

  1. Ionic Polymer Microspheres Bearing a Co(III) -Salen Moiety as a Bifunctional Heterogeneous Catalyst for the Efficient Cycloaddition of CO2 and Epoxides.

    Science.gov (United States)

    Leng, Yan; Lu, Dan; Zhang, Chenjun; Jiang, Pingping; Zhang, Weijie; Wang, Jun

    2016-06-01

    We report a unique strategy to obtain the bifunctional heterogeneous catalyst TBB-Bpy@Salen-Co (TBB=1,2,4,5-tetrakis(bromomethyl)benzene, Bpy=4,4'-bipyridine, Salen-Co=N,N'-bis({4-dimethylamino}salicylidene)ethylenediamino cobalt(III) acetate) by combining a cross-linked ionic polymer with a Co(III) -salen Schiff base. The catalyst showed extra high activity for CO2 fixation under mild, solvent-free reaction conditions with no requirement for a co-catalyst. The synthesized catalyst possessed distinctive spherical structural features, abundant halogen Br(-) anions with good leaving group ability, and accessible Lewis acidic Co metal centers. These unique features, together with the synergistic role of the Co and Br(-) functional sites, allowed TBB-Bpy@Salen-Co to exhibit enhanced catalytic conversion of CO2 into cyclic carbonates relative to the corresponding monofunctional analogues. This catalyst can be easily recovered and recycled five times without significant leaching of Co or loss of activity. Moreover, based on our experimental results and previous work, a synergistic cycloaddition reaction mechanism was proposed.

  2. Template synthesis of monodisperse carbon nanodots

    Science.gov (United States)

    Kurdyukov, D. A.; Eurov, D. A.; Stovpiaga, E. Yu.; Kirilenko, D. A.; Konyakhin, S. V.; Shvidchenko, A. V.; Golubev, V. G.

    2016-12-01

    Monodisperse carbon nanodots in pores of mesoporous silica particles are obtained by template synthesis. This method is based on introducing a precursor (organosilane) into pores, its thermal decomposition with formation of carbon nanodots, and the template removal. Structural analysis of the nanomaterial has been performed, which showed that carbon nanodots have an approximately spherical form and a graphite-like structure. According to dynamic light scattering data, the size of carbon nanodots is 3.3 ± 0.9 nm.

  3. Ultrafast hydrothermal synthesis of high quality magnetic core phenol-formaldehyde shell composite microspheres using the microwave method.

    Science.gov (United States)

    You, Li-Jun; Xu, Shuai; Ma, Wan-Fu; Li, Dian; Zhang, Yu-Ting; Guo, Jia; Hu, Jack J; Wang, Chang-Chun

    2012-07-17

    An ultrafast, facile, and efficient microwave hydrothermal approach was designed to fabricate magnetic Fe(3)O(4)/phenol-formaldehyde (PF) core-shell microspheres for the first time. The structure of the Fe(3)O(4)/PF core-shell microspheres could be well controlled by the in situ polycondensation of phenol and formaldehyde with magnetic Fe(3)O(4) clusters as the seeds in an aqueous solution without any surfactants. The effect of synthetic parameters, such as the feeding amounts of phenol, the dosages of formaldehyde, the reaction temperatures, and the microwave heating time, on the morphologies and sizes of the Fe(3)O(4)/PF microspheres were investigated in details. The phenol-formaldehyde shell is found to be evenly coated on Fe(3)O(4) clusters within 10 min of the irradiation. The as-prepared microspheres were highly uniform in morphology, and the method was found to allow the shell thickness to be finely controlled in the range of 10-200 nm. The properties of the composite microspheres were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetic analysis (TGA), Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The as-prepared Fe(3)O(4)/PF microspheres were monodisperse and highly dispersible in water, ethanol, N,N-dimethyformamide, and acetone, a beneficial quality for the further functionalization and applications of the Fe(3)O(4)/PF microspheres.

  4. Newly designed silver coated-magnetic, monodisperse polymeric microbeads as SERS substrate for low-level detection of amoxicillin

    Science.gov (United States)

    Kibar, Güneş; Topal, Ahmet Emin; Dana, Aykutlu; Tuncel, Ali

    2016-09-01

    We report the preparation of silver-coated magnetic polymethacrylate core-shell nanoparticles for use in surface-enhanced Raman scattering based drug detection. Monodisperse porous poly (mono-2-(methacryloyloxy)ethyl succinate-co-glycerol dimethacrylate), poly (MMES-co-GDMA) microbeads of ca. 5 μm diameter were first synthesized through a multistage microsuspension polymerization technique to serve as a carboxyl-bearing core region. Microspheres were subsequently magnetized by the co-precipitation of ferric ions, aminated through the surface hydroxyl groups and decorated with Au nanoparticles via electrostatic attraction. An Ag shell was then formed on top of the Au layer through a seed-mediated growth process, resulting in micron-sized monodisperse microbeads that exhibit Raman enhancement effects due to the roughness of the Ag surface layer. The core-shell microspheres were used as a new substrate for the detection of amoxicillin at trace concentrations up to 10-8 M by SERS. The proposed SERS platform can be evaluated as a useful tool for the follow-up amoxicillin pollution and low-level detection of amoxicillin in aqueous media.

  5. POE-PEG-POE triblock copolymeric microspheres containing protein. I. Preparation and characterization.

    Science.gov (United States)

    Yang, Y Y; Wan, J P; Chung, T S; Pallathadka, P K; Ng, S; Heller, J

    2001-07-10

    Poly(ortho ester) (POE)-poly (ethylene glycol) (PEG) triblock copolymers (POE-PEG-POE) with different PEG contents were synthesised as carriers for controlled protein delivery. POE-PEG-POE microspheres containing bovine serum albumin (BSA) were prepared using a double-emulsion (water-in-oil-in-water) process. In this first paper of a two-part series, we report the fundamentals of the fabrication and characterization of POE-PEG-POE microspheres. Because the triblock copolymer is more hydrophilic than neat poly(ortho ester), the triblock copolymer yields a more stable first emulsion (water-in-oil) and a greater BSA encapsulation efficiency (90% vs. 30%). No BSA is found on POE-PEG-POE microsphere surfaces measured by X-ray photoelectron spectroscopy, while uniform BSA distributions are observed within the microspheres by confocal microscopy. SEM pictures show that an increase in PEG content results in microspheres with a denser cross-section because of a more stable first emulsion and better affinity between the copolymer and water. POE-PEG(20%)-POE suffers significant swelling during the fabrication process and yields the biggest microspheres. However, the POE-PEG(30%)-POE microspheres are much smaller since the dissolution loss of POE-PEG(30%)-POE in the external water phase may be much higher than that of POE-PEG(20%)-POE. The salt concentration in the external water phase significantly affects the morphology of the resultant microspheres. Microspheres with a dense wall are produced when using pure water as the external water phase. Polymer concentration has less impact on BSA encapsulation efficiency but has a considerable effect on microsphere size and morphology. Increasing the concentration of the polyvinyl alcohol emulsifier does not cause an obvious decrease in microsphere size. However, increased BSA loading results in bigger microspheres.

  6. Doppler cooling a microsphere

    CERN Document Server

    Barker, P F

    2010-01-01

    Doppler cooling the center-of-mass motion of an optically levitated microsphere via the velocity dependent scattering force from narrow whispering gallery mode (WGM) resonances is described. Light that is red detuned from the WGM resonance can be used to damp the center-of-mass motion in a process analogous to the Doppler cooling of atoms. Leakage of photons out of the microsphere when the incident field is near resonant with the narrow WGM resonance acts to damp the motion of the sphere. The scattering force is not limited by saturation, but can be controlled by the incident power. Cooling times on the order of seconds are calculated for a 20 micron diameter silica microsphere trapped within optical tweezers, with a Doppler temperature limit in the microKelvin regime.

  7. Morphology and photoluminescence of self-assembled CaWO4:Sm3+ microspheres: effect of pH and surfactant concentration

    Science.gov (United States)

    Ningombam, Goutam Singh; Nongmaithem, Rajmuhon Singh

    2017-03-01

    Self-assembled CaWO4:Sm3+ microspheres were prepared via surfactant (sodium dodecyl sulfate) mediated hydrothermal method. The effect of pH and the concentration of surfactant on the morphology and photoluminescence of the synthesized phosphors have been studied. Samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence spectroscopy. The microspheres were found to have an average size of 1-2 µm. They were mesoporous in nature and constituted of nanocrystals of about 10-30 nm dimension. The TEM images revealed the interlinking framework of the nano-sized constituents which consequently lead to the formation of mesoporous microspheres. The lowering of pH causes a slight reduction in the size of microspheres which could have been attributed to loss of OH from the nanoparticle surface and subsequent retardation in the adsorption of growing molecular CaWO4:Sm3+ units. Also, as pH increases, crystallinity decreases. The increase in amount of SDS reduced the crystallinity of the materials, destroyed the monodispersity of microspheres and lowered the luminescence output. It was found that lower pH and higher monodispersity of microspheres are quite favourable for high luminescence output.

  8. Mucoadhesive microspheres of propranolol hydrochloride for nasal delivery

    Directory of Open Access Journals (Sweden)

    Dandagi P

    2007-01-01

    Full Text Available Gelatin A microspheres of propranolol hydrochloride for intranasal systemic delivery were developed with the aim to avoid first pass metabolism, to improve the patient compliance, to use an alternative therapy to conventional dosage form, to achieve controlled blood level profiles, and to improve the therapeutic efficacy of propranolol hydrochloride in the treatment of various cardiovascular disorders and as a prophylactic for migraine. Gelatin A microspheres were prepared by emulsion crosslinking method using glutaradehyde as a crosslinking agent. Gelatin and chitosan were used as polymer and co polymer respectively. All the prepared microspheres were evaluated for physical characteristics, such as particle size, incorporation efficiency, swelling index, in vitro bioadhesion using rat jejunum and in vitro drug release in pH 6.6 phosphate buffer. Average particle size of microspheres was found to be in the size range 1-50 mm. Increase in drug and polymer concentration in the formulation increased incorporation efficiency. All the microsphers showed good bioadhesive properties and swelling indices and good sustained release of drug. The data indicates that propranolol hydrochloride release followed Higuchi′s matrix and Peppa′s model. Stability studies showed stability of formulation at all the conditions to which they were subjected.

  9. Preparation and Characterization of Non-porous Superparamagnetic Microspheres with Epoxy Groups by Dispersion Polymerization

    Institute of Scientific and Technical Information of China (English)

    马志亚; 官月平; 刘先桥; 刘会洲

    2005-01-01

    Non-porous superparamagnetic polymer microspheres with epoxy groups were prepared by dispersion polymerization of glycidyl methacrylate (GMA) in the presence of magnetic iron oxide (Fe3O4) nanoparticles coated with oleic acid. The polymerization was carried out in the ethanol/water medium using polyvinylpyrrolidone (PVP) and 2,2’-azobisisobutyronitrile (AIBN) as stabilizer and initiator, respectively. The magnetic microspheres obtained were characterized with scanning electron microscopy (SEM), vibrating sample magnetometry (VSM) and Fourier transform infrared spectroscopy (FTIR). The results showed that the magnetic microspheres had an average size of-1μm with superparamagnetic characteristics. The saturation magnetization was found to be 4.5emu.g-1. There was abundance of epoxy groups with density of 0.028 mmol·g-1 in microspheres. The magnetic PGMA microspheres have extensive potential uses in magnetic bioseparation and biotechnology.

  10. Chitosan and β-cyclodextrin Microspheres as Pulmonary Sustained Delivery Systems

    Institute of Scientific and Technical Information of China (English)

    ZHANG Weifen; CHEN Xiguang; LI Piwu; HE Qiangzhi; ZHOU Huiyun; CHA Dongsu

    2008-01-01

    Chitosan and a-cyclodextrin were used to prepare microspheres with theophylline for pulmonary delivery by spray drying method.The characteristics,mucociliotoxicity,permeation rate and drug release were studied.The drug entrapments of microspheres Ⅰ,Ⅱ and Ⅲ were from 35.70%to 21.09% and 13.33%.while yields and encapsulation efficiencies were higher than 45%and about 90%respectively.with smooth or wrinkled surface surfaces.FT-IR demonstrated theophylline had formed hydrogen bonds with chitosan and a-cyclodextrin.The mierospheres could effectively reduce the ciliotoxicity and easy to penetrate the memberine.The in vitro release of the microspheres was related to the ratio of drug/polymer and microspheres Ⅱ had a prolong release,providing the release of 72.00%in 12 h.The results suggestes that chitosan/ a-cyclodextrin microspheres Ⅱ are a promising carrier as sustained release for pulmonary delivery.

  11. Factorial design approach for optimization of floating microspheres of diltiazem hydrochloride

    Directory of Open Access Journals (Sweden)

    Mangal Singh Panwar

    2015-01-01

    Full Text Available The aim of this study was to perform optimization of floating microspheres of diltiazem hydrochloride for the prolongation of gastric residence time. The microspheres were prepared by a nonaqueous solvent evaporation method using polycarbonate. A full factorial design was applied to optimize the formulation. Preliminary studies revealed that the concentration of polymer and stirring speed significantly affected the characteristics of floating microspheres. The optimum batch of microsphere exhibited smooth surfaces with good flow and packing properties, prolonged sustained drug release, remained buoyant for more than 10 h, high entrapment efficiency up to 97% w/w. Scanning electron microscopy confirmed the hollow structure with particle size in the order of 190 μm. The studies revealed that the increase in concentration of polycarbonate increased the drug release from the floating microspheres. The results of two third full factorial design revealed that the concentration of polycarbonate (X1 and stirring speed (X2 significantly affected drug entrapment efficiency, percentage release.

  12. Floating microspheres of valacyclovir HCl: Formulation, optimization, characterization, in vitro and in vivo floatability studies

    Directory of Open Access Journals (Sweden)

    Nilamgiri Goswami

    2012-01-01

    Full Text Available Floating microspheres are multiple unit Gastroretentive drug delivery systems. Valacyclovir hydrochloride (VCH is L-valyl ester prodrug of acyclovir. VCH degrades in intestinal fluid. The objective was to develop floating microspheres of VCH to localise the drug at upper part of GIT, for improved absorption. Floating microspheres were prepared by W/O emulsification solvent evaporation method using Ethylcellulose (EC as polymer. Particle size and % EE were 550.021±0.241 μm, 79.88±2.236% respectively. in vitro and in vivo floatability studies confirmed floating behaviour of microspheres. VCH loaded floating microspheres can be a suitable alternative to the conventional formulation, by localizing the drug at upper GIT.

  13. Recent advances in the preparation progress of protein/peptide drug loaded PLA/PLGA microspheres.

    Science.gov (United States)

    Xu, Feng-Hua; Zhang, Qiang

    2007-01-01

    Sustained release drug delivery from microparticles is an excellent alternative for daily protein/peptide drug administration protocol. Poly(lactic acid) (PLA) and poly(lactic-co-glycolic acid) (PLGA) are the most commonly used polymer carriers in the development of protein/peptide microspheres. Basically there are three preparation methods for PLA/PLGA microspheres: the solvent extraction/evaporation based multiple emulsion (W/O/W emulsion) method, the phase separation method and the spray drying method. The stability of the protein/pipetide loaded, encapsulation efficiency, and the burst effect of the microspheres are key problems usually met in the preparation of microspheres. In this review the preparation techniques and progress in the development of protein/pipetide microspheres which aimed to stabilize protein/peptide structural integrity, keep the bioactivity of drugs, increase the encapsulation efficiency and improve the release profile were summarized and evaluated.

  14. Microspheres: Microfluidic Generation of Monodisperse and Photoreconfigurable Microspheres for Floral Iridescence-Inspired Structural Colorization (Adv. Mater. 26/2016).

    Science.gov (United States)

    Yeo, Seon Ju; Park, Kyung Jin; Guo, Kai; Yoo, Pil J; Lee, Seungwoo

    2016-07-01

    Flowering plants have advanced their colorization strategies to divide incoming white light into spatially sequenced vivid colors, especially by using 2D grating diffractive motifs. On page 5268, P. J. Yoo, S. Lee, and co-workers conceive a new idea for a microfluidic approach to mimic this wonderful biological strategy and its practical application to the color encoding of colloidal particles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Plasticizer-free microspheres for ionophore-based sensing and extraction based on a methyl methacrylate-decyl methacrylate copolymer matrix

    Energy Technology Data Exchange (ETDEWEB)

    Peper, Shane; Ceresa, Alan; Qin Yu; Bakker, Eric

    2003-12-19

    Plasticizer-free methyl methacrylate-decyl methacrylate (MMA-DMA) microspheres were prepared under mild, non-reactive conditions using a high-throughput particle generator. The particles were perfectly smooth and monodisperse, with a particle diameter of approximately 10.0 {mu}m. In order to evaluate the suitability of the polymer as a matrix for bulk extraction processes, lipophilic sensing components were incorporated into the particles. Particles contained either a H{sup +}-selective chromoionophore (ETH 5294) only (type 1), or a K{sup +}-selective ionophore (BME-44), anionic sites (NaTFPB), and ETH 5294 (type 2). Type 1 particles responded according to an anion-proton coextraction mechanism and demonstrated Hofmeister selectivity by showing a preference for more lipophilic sample anions (ClO{sub 4}{sup -}>NO{sub 3}{sup -}>Cl{sup -}). Particles of type 2 functioned by way of an ion-exchange equilibrium and demonstrated a functional response for K{sup +}, with a dynamic range from 10{sup -1}-10{sup -4} M K{sup +}. These particles also exhibited selectivity comparable to that previously reported for analogous particles made from bis(2-ethylhexyl sebacate) (DOS)-plasticized poly(vinyl chloride) (PVC) and DMA-DOS. In addition, the behavior of both types1 and 2 particles was in agreement with analogous thin film optical sensors (optodes) prepared from MMA-DMA. With the advent of ionophore-based plasticizer-free microspheres a wide variety of ions may potentially be assessed using various popular bead-based sensing strategies, such as lab-on-a-chip technologies, bundled optical fiber arrays, and flow cytometry, without experiencing the deleterious effects resultant of plasticizer leaching.

  16. Preparation and Characterization of Zein and Zein-Chitosan Microspheres with Great Prospective of Application in Controlled Drug Release

    Directory of Open Access Journals (Sweden)

    Vinícius Müller

    2011-01-01

    Full Text Available Biomaterials applied as carriers for controlled drug delivery offer many advantages over the conventional systems. Among them, the increase of treatment effectiveness and also a significant reduction of toxicity, due to their biodegradability property, are some special features. In this work, microspheres based on the protein Zein (ZN and ZN associated to the natural polymer Chitosan (CHI were prepared and characterized. The microspheres of ZN and ZN/CHI were characterized by FT-IR spectroscopy and thermal analysis, and the morphology was analyzed by SEM images. The results confirmed the incorporation of CHI within the ZN-based microspheres. The morphological analysis showed that the CHI added increased the microspheres porosity when compared to the ZN microspheres. The chemical and physical characterization and the morphological analysis allow inferring that ZN/CHI microspheres are good candidates to act as a carrier for controlled drug release.

  17. The research progress of polyimide microspheres%聚酰亚胺微球的研究进展

    Institute of Scientific and Technical Information of China (English)

    方雪; 苏桂明; 马宇良; 陈明月; 张晓臣

    2015-01-01

    聚酰亚胺微球是一类具有耐高温、耐溶剂性以及较低的介电性能的高比表面积的高分子材料,具有广阔的应用前景。通过探讨几类聚酰亚胺实心微球、中空微球、多孔微球以及复合微球的研究,发现这些方法仍然存在各种不同的缺点和问题。%Polyimide microspheres were considered as a class of polymer materials with high temperature resistance, solvent resistance and low dielectric properties and high specific surface area. In this article, the research progress of various polyimide microspheres including solid microspheres, hollow microspheres, porous microspheres and composite microspheres were reviewed.

  18. Doped zinc oxide microspheres

    Science.gov (United States)

    Arnold, Jr., Wesley D.; Bond, Walter D.; Lauf, Robert J.

    1993-01-01

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel.

  19. Polyvinyl pyridine microspheres

    Science.gov (United States)

    Rembaum, Alan (Inventor); Gupta, Amitava (Inventor); Volksen, Willi (Inventor)

    1980-01-01

    Microspheres are produced by cobalt gamma radiation initiated polymerization of a dilute aqueous vinyl pyridine solution. Addition of cross-linking agent provides higher surface area beads. Addition of monomers such as hydroxyethylmethacrylate acrylamide or methacrylamide increases hydrophilic properties and surface area of the beads. High surface area catalytic supports are formed in the presence of controlled pore glass substrate.

  20. Coacervate-like microspheres from lysine-rich proteinoid

    Science.gov (United States)

    Rohlfing, D. L.

    1975-01-01

    Microspheres form isothermally from lysine-rich proteinoid when the ionic strength of the solution is increased with NaCl or other salts. Studies with different monovalent anions and with polymers of different amino acid composition indicate that charge neutralization and hydrophobic bonding contribute to microsphere formation. The particles also form in sea water, especially if heated or made slightly alkaline. The microspheres differ from those made from acidic proteinoid but resemble coacervate droplets in some ways (isothermal formation, limited stability, stabilization by quinone, uptake of dyes). Because the constituent lysine-rich proteinoid is of simulated prebiotic origin, the study is interpreted to add emphasis to and suggest an evolutionary continuity for coacervation phenomena.

  1. Protein microspheres as suitable devices for piroxicam release.

    Science.gov (United States)

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

    2012-04-01

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

  2. Ketoprofen spray-dried microspheres based on Eudragit RS and RL: study of the manufacturing parameters.

    Science.gov (United States)

    Rassu, Giovanna; Gavini, Elisabetta; Spada, Gianpiera; Giunchedi, Paolo; Marceddu, Salvatore

    2008-11-01

    The preparation of ketoprofen spray-dried microspheres can be affected by the long drug recrystallization time. Polymer type and drug-polymer ratio as well as manufacturing parameters affect the preparation. The purpose of this work was to evaluate the possibility to obtain ketoprofen spray-dried microspheres using the Eudragit RS and RL; the influence of the spray-drying parameters on morphology, dimension, and physical stability of microspheres was studied. Ketoprofen microspheres based on Eudragit blend can be prepared by spray-drying and the nebulization parameters do not influence significantly particle properties; nevertheless, they can be affected by drying and storage methods. No effect of the container material is found.

  3. Formation of cagelike sulfonated polystyrene microspheres via swelling-osmosis process and loading of CdS nanoparticles.

    Science.gov (United States)

    Weng, Hanqin; Huang, Xuefeng; Wang, Mozhen; Ji, Xiang; Ge, Xuewu

    2013-12-10

    In this report, we studied the formation mechanism of cagelike polymer microspheres fabricated conveniently and efficiently through a swelling-osmosis process of sulfonated polystyrene (SPS) microspheres in a ternary mixed solvent (water/ethanol/heptane). The scanning electron microscopy and transmission electron microscopy observations indicated that the morphology of the final cagelike SPS microspheres is mainly controlled by the composition of the mixed solvent and the swelling temperature. Considering the solubility parameters of related reagents and the low interface tension of heptane and the aqueous solution of ethanol (only 6.9 mN/m), we confirm that the porogen procedure starts from the swelling of SPS microspheres by heptane, followed by the osmosis process of water molecules into the swollen SPS microspheres forced by the strong hydrophilicity of -SO3H group. The water molecules permeated into SPS microspheres will aggregate into water pools, which form the pores after the microspheres are dried. These prepared cagelike SPS microspheres are further served as the scaffold for the in situ generated CdS nanoparticles under γ-ray radiation. The CdS/SPS composite microspheres show good fluorescence performance. This work shows that the cagelike SPS microspheres have a wide industrial application prospect due to their economical and efficient preparation and loading nanoparticles.

  4. Novel biphasic separations utilising highly selective molecularly imprinted polymers as biorecognition solvent extraction agents.

    Science.gov (United States)

    Castell, Oliver K; Allender, Christopher J; Barrow, David A

    2006-10-15

    Molecularly imprinted polymers (MIPs) represent a class of artificial receptors that promise an environmentally robust alternative to naturally occurring biorecognition elements of biosensing devices and systems. However, in general, the performance of conventional MIPs in aqueous environments is poor. In the study reported here, this limitation has been addressed by the novel application of MIPs as a solvent extraction solid phase in a biphasic solvent system. This paper describes a previously unreported use of MIPs as solvent extraction reagents, their successful application to aqueous sample media and the opportunities for utilisation of this unique system in novel biosensing and separation procedures. This study demonstrates the development of a novel biphasic solvent system utilising MIP in the extracting phase to enhance both efficiency and selectivity of a simple two phase liquid extraction. Monodisperse propranolol imprinted polymer microspheres [p(divinylbenzene-co-methacrylic acid)] were prepared by precipitation polymerisation. Initially, the affinity of the polymers for (R,S)-propranolol was assessed by established techniques whereby the MIP demonstrated greater affinity for the template than did the non-imprinted control polymer (NIP). Importantly, MIP performance was also assessed using the novel dual solvent system. The depletion of (R,S)-propranolol from the aqueous phase into the polymer containing organic phase was determined. When compared to control extractions containing no polymer the presence of MIP in the extracting solvent phase resulted in an increased extraction of (R,S)-propranolol from the aqueous phase. Importantly, this extraction was significantly greater in the presence of MIP when compared to NIP. This unique principle generates opportunities for MIP based extractions and chemical enrichments in industrial applications, offering commercial, ecological and practical advantages to traditional solvent extraction techniques. The

  5. Preparation of Conducting Poly N-methylaniline Microsphere and Its Antibacterial Performance to Sulfate Reducing Bacteria

    Institute of Scientific and Technical Information of China (English)

    LIU Hongfan; HUANG Li; HUANG Zhuo; QI Gongtai; KEI Nanada; Yutaka Harima

    2008-01-01

    Microspheres of conducting polymers poly N-methylaniline(PNMA)were successfully synthesized through oxidation of N-methylaniline without any template.The average diameter of the M ammonium persulfate in 0.2 M of HCIO4 solution.The size of microspheres can be controlled by changing reaction time and temperature.The acid concentration was critical for the formation of microspheres with smooth surfaces.The excellent antibacterial performance of PNMA in novolac epoxy coating to sulfate reducing bacteria was demonstrated.Moreover,in API media,PNMA inhibited growth of SRB and then reduced the corrosion rate of carbon steel remarkably.

  6. Recent Progress in the Design of Monodisperse, Sequence-Defined Macromolecules.

    Science.gov (United States)

    Solleder, Susanne C; Schneider, Rebekka V; Wetzel, Katharina S; Boukis, Andreas C; Meier, Michael A R

    2017-05-01

    This review describes different synthetic strategies towards sequence-defined, monodisperse macromolecules, which are built up by iterative approaches and lead to linear non-natural polymer structures. The review is divided in three parts: solution phase-, solid phase-, and fluorous- and polymer-tethered approaches. Moreover, synthesis procedures leading to conjugated and non-conjugated macromolecules are considered and discussed in the respective sections. A major focus in the evaluation is the applicability of the different approaches in polymer chemistry. In this context, simple procedures for monomer and oligomer synthesis, overall yields, scalability, purity of the oligomers, and the achievable level of control (side-chains, backbone, stereochemistry) are important benchmarks. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Study on encapsulation of chlorine dioxide in gelatin microsphere for reducing release rate

    OpenAIRE

    Ci, Ying; Wang,Lin; Guo, YanChuan; Sun, Ruixue; Wang, Xijie; Li, Jinyou

    2015-01-01

    Objective: This study aims to explore the effects of encapsulation of chlorine dioxide in a hydrophilic biodegradable polymer gelatin to reduce its release rate. Methods: An emulsification-coacervation method was adopted. The characterizations of chlorine dioxide-gelatin microspheres were described. Using UV-vis spectrophotometer the λmax of chlorine dioxide was observed at 358 nm. The particle size and distribution of chlorine oxide-gelatin microspheres was measured by a dynamic light scatte...

  8. Optical Sensing Properties of Dithiocarbamate-Functionalized Microspheres, Using a Polyvinylpyridine-Polyvinylbenzyl Chloride Copolymer

    Directory of Open Access Journals (Sweden)

    Ziad M. Shakhsher

    2010-10-01

    Full Text Available In this study, a new modified optical chemical sensor based on swellable polymer microspheres is developed using a 5% copolymer of polyvinylpyridine-polyvinyl -benzyl chloride microspheres functionalized as the corresponding dithiocarbamate. This sensor demonstrated significant enhancements in sensitivity, dynamic range and response time. These improvements are related to the presence of pyridine in the polymer backbone, which is believed to increase the space between the groups, thus decreasing steric hindrance, and hence increasing substitution of the dithiocarbamate group. The hydrophilicity of pyridine also allows free movement of the solvent and analyte to and from the inside of the microspheres. These dithiocarbamate-derivatized polymer microspheres were embedded in a hydrogel matrix of polyvinylalcohol cross-linked with glutaraldehyde. This sensor responded selectively to Hg2+ solutions of different concentrations (1 × 10−5 M to 0.1 M. The observed turbidity measured as absorbance varied between 1.05 and 1.75 units at a wavelength of 700 nm. The response is based on the interaction between the metal cations with the negative charges of the deprotonated dithiocarbamate functional group, which led to neutratization of the charges and thus to polymer shrinking. As a result, an increase in the turbidity of the sensing element due to a change in the refractive index between the hydrogel and the polymer microspheres occured. The changes in the turbidity of the sensing element were measured as absorbance using a conventional spectrophotometer.

  9. Optical sensing properties of dithiocarbamate-functionalized microspheres, using a polyvinylpyridine-polyvinylbenzyl chloride copolymer.

    Science.gov (United States)

    Shakhsher, Ziad M; Odeh, Imad M A; Rajabi, Inas M S; Khatib, Mahmoud K

    2010-01-01

    In this study, a new modified optical chemical sensor based on swellable polymer microspheres is developed using a 5% copolymer of polyvinylpyridine-polyvinyl-benzyl chloride microspheres functionalized as the corresponding dithiocarbamate. This sensor demonstrated significant enhancements in sensitivity, dynamic range and response time. These improvements are related to the presence of pyridine in the polymer backbone, which is believed to increase the space between the groups, thus decreasing steric hindrance, and hence increasing substitution of the dithiocarbamate group. The hydrophilicity of pyridine also allows free movement of the solvent and analyte to and from the inside of the microspheres. These dithiocarbamate-derivatized polymer microspheres were embedded in a hydrogel matrix of polyvinylalcohol cross-linked with glutaraldehyde. This sensor responded selectively to Hg(2+) solutions of different concentrations (1 × 10(-5) M to 0.1 M). The observed turbidity measured as absorbance varied between 1.05 and 1.75 units at a wavelength of 700 nm. The response is based on the interaction between the metal cations with the negative charges of the deprotonated dithiocarbamate functional group, which led to neutratization of the charges and thus to polymer shrinking. As a result, an increase in the turbidity of the sensing element due to a change in the refractive index between the hydrogel and the polymer microspheres occurred. The changes in the turbidity of the sensing element were measured as absorbance using a conventional spectrophotometer.

  10. Dual Drug Loaded Biodegradable Nanofibrous Microsphere for Improving Anti-Colon Cancer Activity

    Science.gov (United States)

    Fan, Rangrang; Li, Xiaoling; Deng, Jiaojiao; Gao, Xiang; Zhou, Liangxue; Zheng, Yu; Tong, Aiping; Zhang, Xiaoning; You, Chao; Guo, Gang

    2016-06-01

    One of the approaches being explored to increase antitumor activity of chemotherapeutics is to inject drug-loaded microspheres locally to specific anatomic sites, providing for a slow, long term release of a chemotherapeutic while minimizing systemic exposure. However, the used clinically drug carriers available at present have limitations, such as their low stability, renal clearance and residual surfactant. Here, we report docetaxel (DOC) and curcumin (CUR) loaded nanofibrous microspheres (DOC + CUR/nanofibrous microspheres), self-assembled from biodegradable PLA-PEO-PPO-PEO-PLA polymers as an injectable drug carrier without adding surfactant during the emulsification process. The obtained nanofibrous microspheres are composed entirely of nanofibers and have an open hole on the shell without the assistance of a template. It was shown that these DOC + CUR/nanofibrous microspheres could release curcumin and docetaxel slowly in vitro. The slow, sustained release of curcumin and docetaxel in vivo may help maintain local concentrations of active drug. The mechanism by which DOC + CUR/nanofibrous microspheres inhibit colorectal peritoneal carcinomatosis might involve increased induction of apoptosis in tumor cells and inhibition of tumor angiogenesis. In vitro and in vivo evaluations demonstrated efficacious synergistic antitumor effects against CT26 of curcumin and docetaxel combined nanofibrous microspheres. In conclusion, the dual drug loaded nanofibrous microspheres were considered potentially useful for treating abdominal metastases of colorectal cancer.

  11. Formulation and evaluation of Zidovudine loaded chitosan Microspheres for controlled release

    Directory of Open Access Journals (Sweden)

    Kesari Asha

    2012-03-01

    Full Text Available The aim of this study was to formulate and evaluate zidovudine loaded chitosan microspheres for controlled drug release. Microspheres were prepared by emulsification method using gluteraldehyde as crosslinking agent. The prepared microspheres were characterized for their yield and drug loading, as well by Fourier transform infrared spectroscopy (FTIR, X-ray powder diffractometry and Scanning electron microscopy. The in vitro release studies were performed in pH 7.4, phosphate buffer. The prepared microspheres were free flowing and spherical in shape. The drugloaded microspheres showed 72-94% of entrapment and release was extended up to 12h. The infrared spectra showed stable character of zidovudine in the drugloaded microspheres and revealed the absence of drugpolymer interactions. X-ray diffraction patterns showed that there was decrease in crystallinity of the drug. Scanning electron microscopy study revealed that the microspheres were spherical and porous in nature. It was found that the drug: polymer ratio, the stirring speed, the concentration of surfactant, and the amount of gluteraldehyde used for crosslinking were the most significant variables which influenced the size of the chitosan microspheres under the applied experimental condition.

  12. Thermal expansion of an epoxy-glass microsphere composite

    Science.gov (United States)

    Price, H. L.; Burks, H. D.

    1977-01-01

    The thermal expansion of a composite of epoxy (diglycidyl ether of bisphenol A) and solid glass microspheres was investigated. The microspheres had surfaces which were either untreated or treated with a silicone release agent, an epoxy coupling agent, or a general purpose silane coupling agent. Both room temperature (about 300 K) and elevated temperature (about 475 K) cures were used for the epoxy. Two microsphere size ranges were used, about 50 microns, which is applicable in filled moldings, and about 125 microns, which is applicable as bond line spacers. The thermal expansion of the composites was measured from 300 to 350 K or from 300 to 500 K, depending on the epoxy cure temperature. Measurements were made on composites containing up to .6 volume fraction microspheres. Two predictive models, which required only the values of thermal expansion of the polymer and glass and their specific gravities, were tested against the experimental data. A finite element analysis was made of the thermal strain of a composite cell containing a single microsphere surrounded by a finite-thickness interface.

  13. Solvent/Non-Solvent Sintering To Make Microsphere Scaffolds

    Science.gov (United States)

    Laurencin, Cato T.; Brown, Justin L.; Nair, Lakshmi

    2011-01-01

    A solvent/non-solvent sintering technique has been devised for joining polymeric microspheres to make porous matrices for use as drug-delivery devices or scaffolds that could be seeded with cells for growing tissues. Unlike traditional sintering at elevated temperature and pressure, this technique is practiced at room temperature and pressure and, therefore, does not cause thermal degradation of any drug, protein, or other biochemical with which the microspheres might be loaded to impart properties desired in a specific application. Also, properties of scaffolds made by this technique are more reproducible than are properties of comparable scaffolds made by traditional sintering. The technique involves the use of two miscible organic liquids: one that is and one that is not a solvent for the affected polymer. The polymeric microspheres are placed in a mold having the size and shape of the desired scaffold, then the solvent/non-solvent mixture is poured into the mold to fill the void volume between the microspheres, then the liquid mixture is allowed to evaporate. Some of the properties of the resulting scaffold can be tailored through choice of the proportions of the liquids and the diameter of the microspheres.

  14. Preparation of Bauxite Ceramic Microsphere

    Institute of Scientific and Technical Information of China (English)

    CHENG Xiaosu; LIU Pingan; LI Xiuyan; SHUI Anze; ZENG Lingke

    2007-01-01

    Ceramic microspheres were prepared by using Chinese bauxite as raw materials through the centrifugal spray drying method. The control technology of microsphere size, degree of sphericity was researched. The ceramic microspheres were sintered by a double sintering process. The microstructure and composition of ceramic microsphere were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray energy spectroscopy. The results show that the degree of sphericity of the ceramic microsphere was good and the particle size was 10-100 μm. The XRD analysis reveals that the main crystalline phase of the ceramic microsphere was α- Al2O3 and mullite (3Al2O3·2SiO2). The product can be used as reinforced material for composite material, especially for antiskid and hard wearing aluminum alloy coating.

  15. Characterization and in vitro degradation of salicylate-derived poly(anhydride-ester microspheres).

    Science.gov (United States)

    Yeagy, Brian A; Prudencio, Almudena; Schmeltzer, Robert C; Uhrich, Kathryn E; Cook, Thomas J

    2006-09-01

    The aim of this study was to investigate how glass transition temperature (Tg) influenced polymer microsphere formation and degradation of three chemically, similar novel salicylatebased poly(anhydride-esters): poly[1,6-bis(o-carboxyphenoxy)hexanoate] (CPH), Tg = 59 degrees C; poly[1,8-bis(o-carboxyphenoxy)octanoate] (CPO), Tg = 30 degrees C; and poly[1,10-bis(ocarboxyphenoxy) decanoate] (CPD), Tg = 27 degrees C. Microspheres of these polymers were prepared using a modified oil-in-water solvent evaporation method and processed by either resuspension or washed by centrifugation. The morphology of the microspheres determined by scanning electron microscopy (SEM) revealed that an extra washing step appears to increase aggregation as the Tg decreases; whereas only limited aggregation occurred in the polymer with the lowest Tg, CPD, in those not washed by centrifugation. Residual polyvinyl alcohol apparently affected the drug release rates from the microspheres by a stabilization process that produced an 8 h lag time and a 5% decrease in the amount of drug released over a 7 day period compared to microspheres washed free of PVA. These results demonstrate that salicylate-based poly(anhydride-esters) with sufficiently high Tgs, can be processed into microspheres that release salicylate over a time period amenable for drug delivery applications.

  16. FORMULATION AND EVALUATION OF TIZANIDINE HYDROCHLORIDE MICROSPHERES BY USING 32 FULL FACTORIAL DESIGNS

    Directory of Open Access Journals (Sweden)

    Adimoolam Senthil

    2011-09-01

    Full Text Available Tizanidine hydrochloride is a centrally acting α-2 adrenergic agonist muscle relaxant. In the present study an attempt has been made to formulate and evaluate tizanidine hydrochloride microspheres by using hydroxypropylmethylcellulose K4M and carboxymethyl cellulose as polymers. Tizanidine hydrochloride microspheres were prepared by simple emulsification phase separation technique using glutaraldehyde as a cross-linking agent. Twenty preliminary trial batches, B1-B20 batches of microspheres were prepared by using different volume (2 to 10 ml of glutaraldehyde as cross-linking agent, cross-linking time 1 to 4 hours and 3:1 ratio of polymer-to-drug with two different polymers. From these twenty batches of each polymer, the optimized formulation is selected based on the percentage of mucoadhesion, drug entrapment efficiency and sphericity of microspheres. A 32 full factorial design was employed to study the effect of independent variables, polymer-to-drug ratio (X1, and stirring speed (X2 on dependent variables percentage of mucoadhesion, drug entrapment efficiency, swelling index and in-vitro drug release study. The drug polymer compatibility studies were carried out using FTIR. Among the two polymers hydroxypropylmethyl cellulose K4M exhibited a high drug entrapment efficiency of 79% and a swelling index 1.260, percentage of mucoadhesive after 1hour was 80% and the drug release was also sustained for more than 10 hours.

  17. Microfluidic Production of Monodisperse Perfluorocarbon Microdroplets

    Science.gov (United States)

    Li, David; Schalte, Kevin; Fowlkes, J. Brian; Bull, Joseph

    2010-11-01

    Acoustic droplet vaporization (ADV) is process in which liquid perfluorocarbon (PFC) microdroplets are vaporized using focused ultrasound to form gas bubbles that are approximately 125 times larger in volume. Gas embolotherapy is a novel cancer treatment that uses ADV in vivo to strategically form gas emoboli, which can lodge in the microcirculation and starve tumors. Current methods to produce PFC microdroplets, such has high speed shaking or sonication, result in polydisperse droplet distributions where a fraction of droplets fall within the 2-10 microns range. In the clinical application with such a droplet distribution, large droplets are filtered by the lungs and small droplets result in bubbles that are too small to lodge in the tumor vasculature. Consequently, there is a need for a monodisperse droplet distribution. A microfluidic based device has been developed in order to produce such monodisperse PFC microdroplets. The device used hydrodynamic flow focusing to create droplets with a mean diameter less than 10 microns in diameter. This work is supported by NIH grant R01EB006476.

  18. BIOCOMPATIBLE FLUORESCENT MICROSPHERES: SAFE PARTICLES FOR MATERIAL PENETRATION STUDIES

    Energy Technology Data Exchange (ETDEWEB)

    farquar, G; Leif, R

    2008-09-12

    Biocompatible polymers with hydrolyzable chemical bonds are being used to produce safe, non-toxic fluorescent microspheres for material penetration studies. The selection of polymeric materials depends on both biocompatibility and processability, with tailored fluorescent properties depending on specific applications. Microspheres are composed of USFDA-approved biodegradable polymers and non-toxic fluorophores and are therefore suitable for tests where human exposure is possible. Micropheres are being produced which contain unique fluorophores to enable discrimination from background aerosol particles. Characteristics that affect dispersion and adhesion can be modified depending on use. Several different microsphere preparation methods are possible, including the use of a vibrating orifice aerosol generator (VOAG), a Sono-Tek atomizer, an emulsion technique, and inkjet printhead. The advantages and disadvantages of each method will be presented and discussed in greater detail along with fluorescent and charge properties of the aerosols. Applications for the fluorescent microspheres include challenges for biodefense system testing, calibrants for biofluorescence sensors, and particles for air dispersion model validation studies.

  19. Hydrothermal synthesis of 3D hollow porous Fe3O4 microspheres towards catalytic removal of organic pollutants.

    Science.gov (United States)

    Wang, Xiansong; Huang, He; Li, Guoqing; Liu, Yi; Huang, Jiale; Yang, Da-Peng

    2014-01-01

    Three-dimensional hollow porous superparamagnetic Fe3O4 microspheres were synthesized via a facile hydrothermal process. A series of characterizations done with X-ray diffraction, Brunauer-Emmett-Teller method, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy indicated that the production of Fe3O4 microspheres possessed good monodispersity, uniform size distribution, hollow and porous structural characters, and strong superparamagnetic behavior. The obtained Fe3O4 microspheres have a diameter of ca. 300 nm, which is composed of many interconnected nanoparticles with a size of ca. 20 nm. The saturation magnetization is 80.6 emu·g(-1). The as-prepared products had promising applications as novel catalysts to remove organic pollutants (methylene blue) from wastewater in the presence of H2O2 and ultrasound irradiation.

  20. Elongational viscosity of monodisperse and bidisperse polystyrene melts

    DEFF Research Database (Denmark)

    Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole

    2006-01-01

    The start-up and steady uniaxial elongational viscosity have been measured for two monodisperse polystyrene melts with molecular weights of 52 and 103 kg/mole, and for three bidisperse polystyrene melts. The monodisperse melts show a maximum in the steady elongational viscosity vs. the elongation...

  1. Functional magnetic microspheres

    Science.gov (United States)

    Yen, Shiao-Ping S. (Inventor); Rembaum, Alan (Inventor); Landel, Robert F. (Inventor)

    1981-01-01

    Functional magnetic particles are formed by dissolving a mucopolysaccharide such as chitosan in acidified aqueous solution containing a mixture of ferrous chloride and ferric chloride. As the pH of the solution is raised magnetite is formed in situ in the solution by raising the pH. The dissolved chitosan is a polyelectrolyte and forms micelles surrounding the granules at pH of 8-9. The chitosan precipitates on the granules to form microspheres containing the magnetic granules. On addition of the microspheres to waste aqueous streams containing dissolved ions, the hydroxyl and amine functionality of the chitosan forms chelates binding heavy metal cations such as lead, copper, and mercury and the chelates in turn bind anions such as nitrate, fluoride, phosphate and borate.

  2. STUDY ON SYNTHESIS OF SELF CORSS LINKED POLYSTYRENE LATEX MICROSPHERES

    Institute of Scientific and Technical Information of China (English)

    DaiLizong; ZouYousi; 等

    1997-01-01

    Emulsifier-free emulsion polymerization of styrene in the presence of β-hydroxy propyl acrylate was studied.The emulsifier-free self cross linked polystyrene latex microspheres was obtained.Monomer conversion is higher than 90% when [St],[β-HPA],[KPS] is 2.66,0.228,and 5.8×10-3mol/L respectively under 80℃ for 5h.The mono-dispersed latex particle diameter and colloidal particle concentration were given as D=0.23um,N=3.13×1013/cm3 by TEM analyse,The factors of influencing latex stability were discussed.Thecopolymer was characterized by IR and dissolution experiment.The apparent activation energy of polymerization and polymerization rate constant were obtained to be 78.7KJ/mol and 514.4/mol.s respectively.

  3. Covalent immobilization of lipases on monodisperse magnetic microspheres modified with PAMAM-dendrimer

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Weiwei [Lanzhou University, State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Institute of Biochemical Engineering and Environmental Technology (China); Zhang, Yimei [Suzhou Research Academy of North China Electric Power University (China); Hou, Chen; Pan, Duo; He, Jianjun; Zhu, Hao, E-mail: zhuhao07@lzu.edu.cn [Lanzhou University, State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Institute of Biochemical Engineering and Environmental Technology (China)

    2016-02-15

    This paper reported an immobilization of Candida rugosa lipase (CRL) onto PAMAM-dendrimer-grafted magnetic nanoparticles synthesized by a modified solvothermal reduction method. The dendritic magnetic nanoparticles were amply characterized by several instrumental measurements, and the CRL was covalently anchored on the three generation supports with glutaraldehyde as coupling reagent. The amount of immobilized enzyme was up to 150 mg/g support and the factors related with the enzyme activity were investigated. The immobilization of lipase improved their performance in wider ranges of pH and temperature. The immobilized lipase exhibited excellent thermal stability and reusability in comparison with free enzyme and can be reused 10 cycles with the enzymatic activity remained above 90 %. The properties of lipase improved obviously after being immobilized on the dendritic supports. The inactive immobilized lipase could be regenerated with glutaraldehyde and Cu{sup 2+}, respectively. This synthetic strategy was facile and eco-friendly for applications in lipase immobilization.

  4. High-throughput Screening:Synthesis of a Novel Fluorescent Microspheres

    Institute of Scientific and Technical Information of China (English)

    LI Song-Jun; LIU Bai-ling

    2004-01-01

    As one of efficient analytes, fluorescent microspheres have shown much usability on many biochemical and biomedical processes. Recent applications with fluorescent microspheres have included cytokine quantitation, single nucleotide polymorphism genotyping, phosphorylated protein detection, and characterization of the molecular interaction of nuclear receptors. These,coupled with the rapid advances in molecular biology and synthesis techniques of drugs, have presented a basis for drug screening in a high-throughput format. Based on fluorescent microspheres,earlier assay formats of HTS relied mainly on proximity-dependent energy transfer including scintillation proximity assay (SPA) (Amersham Pharmacia Biotech) and FlashPlatesTM (NEN Life Science Products, Boston, MA). Indeed, drug screening-based such fluorescent emission is still accounting for about 20~50% of current content of high-throughput screening (HTS). Now, SPA is almost a standard technique in common HTS-lab. In literature, SPA microspheres is generally prepared from inorganic scintillators such as yttrium silicate and hydrophobic polymers such as polyvinyl toluene. However, in HTS research, such microspheres often show the disadvantages of strong hydrophobicity and low quantum efficiency. The strong hydrophobicity is mainly attributed to the hydrophobic monomer, vinyl toluene. The low quantum efficiency can be as a result of low transparence of the polymer, polyvinyl toluene. Thus, the subsequent treatments for such microspheres, so as coat a polyhydroxy film to decrease the hydrophobicity, are actually considerably complicated.It has been well known that poly(methyl methacrylate) (PMMA), a good biocompatible polymer with not only adequate mechanical strength but also excellent transparence, can be regarded as an ideal candidate material for fluorescent matrix. In present study, methyl methacrylate as monomer and 2,5-diphenyloxazole (DPO) as fluorescent dye were used to the fluorescent microspheres. In

  5. Formulation and evaluation of microsphere based oro dispersible tablets of itopride hcl

    Directory of Open Access Journals (Sweden)

    Shah Sanjay

    2012-09-01

    Full Text Available Abstract Background The purpose of the present work is to mask the intensely bitter taste of Itopride HCl and to formulate an Oro dispersible tablet (ODT of the taste-masked drug by incorporation of microspheres in the tablets for use in specific populations viz. pediatrics, geriatrics and patients experiencing difficulty in swallowing. Methods With this objective in mind, microspheres loaded with Itopride HCl were prepared by solvent evaporation method using acetone as solvent for pH-sensitive polymer, Eudragit EPO and light liquid paraffin as the encapsulating medium. The prepared microspheres were characterized with regard to yield, drug content, flow properties, particle size and size distribution, surface features, in vitro drug release and taste. The ODTs so prepared from these microspheres were evaluated for hardness, thickness, weight variation, friability, disintegration time, drug content, wetting time, water absorption ratio, moisture uptake, in vitro dispersion, in vitro disintegration, in vitro drug release and stability. Results The average size of microspheres was found to be satisfactory in terms of the size and size distribution. Microspheres prepared were of a regular spherical shape. Comparison of the dissolution profiles of microspheres in different pH media showed that microspheres having drug: polymer ratio of 1:2 produced a retarding effect in simulated salivary fluid (pH 6.8 and were further used for formulation into ODTs after addition of suitable amounts of excipients such as superdisintegrant, diluent, sweetener and flavor of directly compressible grade. Conclusions Effective taste-masking was achieved for Itopride HCl by way of preparation of microspheres and ODTs of acceptable characteristics.

  6. Formulation and Evaluation of Microsphere Based Oro Dispersible Tablets of Itopride Hcl

    Directory of Open Access Journals (Sweden)

    S.S Agrawal

    2012-09-01

    Full Text Available Background The purpose of the present work is to mask the intensely bitter taste of Itopride HCl and to formulate an Oro dispersible tablet (ODT of the taste-masked drug by incorporation of microspheres in the tablets for use in specific populations viz. pediatrics, geriatrics and patients experiencing difficulty in swallowing.Methods:With this objective in mind, microspheres loaded with Itopride HCl were prepared by solvent evaporation method using acetone as solvent for pH-sensitive polymer, Eudragit EPO and light liquid paraffin as the encapsulating medium. The prepared microspheres were characterized with regard to yield, drug content, flow properties, particle size and size distribution, surface features, in vitro drug release and taste. The ODTs so prepared from these microspheres were evaluated for hardness, thickness, weight variation, friability, disintegration time, drug content, wetting time, water absorption ratio, moisture uptake, in vitro dispersion, in vitro disintegration, in vitro drug release and stability. Results:The average size of microspheres was found to be satisfactory in terms of the size and size distribution. Microspheres prepared were of a regular spherical shape. Comparison of the dissolution profiles of microspheres in different pH media showed that microspheres having drug: polymer ratio of 1:2 produced a retarding effect in simulated salivary fluid (pH 6.8 and were further used for formulation into ODTs after addition of suitable amounts of excipients such as superdisintegrant, diluent, sweetener and flavor of directly compressible grade. ConclusionsEffective taste-masking was achieved for Itopride HCl by way of preparation of microspheres and ODTs of acceptable characteristics.

  7. Synthesis and characterization of porous microspheres bearing pyrrolidone units

    Energy Technology Data Exchange (ETDEWEB)

    Maciejewska, M., E-mail: mmacieje@umcs.pl; Kołodyńska, D.

    2015-01-15

    Porous microspheres of glycydyl methacrylate (GMA) cross-linked with trimethylolpropane trimethacrylate (TRIM) were prepared with toluene as porogen by suspension-emulsion polymerization. With increasing molar ratio of the functional monomer to cross-linker, the epoxy group content increases significantly whereas the parameters of porous structure (specific surface area and total pore volume) decreases. In order to obtain adsorbents bearing functional groups the porous methacrylate network was modified by subsequent reaction with pyrrolidone. The materials were studied using elemental analysis, infrared spectroscopy, atomic force microscopy (AFM), attenuated total reflection (ATR) spectroscopy, Raman spectroscopy, thermal gravimetry. Additionally, polymers sorption capacity towards Cu(II) was investigated. - Highlights: • Porous microspheres with reactive epoxy group were synthesized. • Highly developed porous structure was created. • Pyrrolidone units were incorporated during ring–opening reaction. • Polymers sorption capacity towards Cu (II) was investigated.

  8. Formulation and characterization of microspheres loaded with imatinib for sustained delivery.

    Science.gov (United States)

    Ramazani, F; Chen, W; Van Nostrum, C F; Storm, G; Kiessling, F; Lammers, T; Hennink, W E; Kok, R J

    2015-03-30

    The aim of this study was the development of imatinib-loaded poly(d,l-lactide-co-glycolide) (PLGA) microspheres with high loading efficiency which can afford continuous release of imatinib over a prolonged period of time. Imatinib mesylate loaded PLGA microspheres with a size of 6-20 μm were prepared by a double emulsion (W1/O/W2) method using dichloromethane as volatile solvent. It was found that the microspheres were spherical with a non-porous surface; imatinib loading efficiency (LE) was highly dependent on the pH of the external water phase (W2). By increasing the pH of W2 phase above the highest pKa of imatinib (pKa 8.1), at which imatinib is mainly uncharged, the LE increased from 10% to 90% (pH 5.0 versus pH 9.0). Conversely, only 4% of its counter ion, mesylate, was retained in the microspheres at the same condition (pH 9.0). Since mesylate is highly water soluble, it is unlikely that it partitions into the organic phase. We demonstrated, using differential scanning calorimetry (DSC), that imatinib was molecularly dispersed in the polymeric matrix at loadings up to 8.0%. At higher drug loading, imatinib partially crystallized in the matrix. Imatinib microspheres released their cargo during three months by a combination of diffusion through the polymer matrix and polymer erosion. In conclusion, we have formulated imatinib microspheres with high LE and LC. Although we started with a double emulsion of imatinib mesylate, the obtained microspheres contained imatinib base which was mainly molecularly dispersed in the polymer matrix. These microspheres release imatinib over a 3-month period which is of interest for local treatment of cancer.

  9. A micro-reactor for preparing uniform molecularly imprinted polymer beads.

    Science.gov (United States)

    Zourob, Mohammed; Mohr, Stephan; Mayes, Andrew G; Macaskill, Alexandra; Pérez-Moral, Natalia; Fielden, Peter R; Goddard, Nicholas J

    2006-02-01

    In this study, uniform spherical molecularly imprinted polymer beads were prepared via controlled suspension polymerization in a spiral-shaped microchannel using mineral oil and perfluorocarbon liquid as continuous phases. Monodisperse droplets containing the monomers, template, initiator, and porogenic solvent were introduced into the microchannel, and particles of uniform size were produced by subsequent UV polymerization, quickly and without wasting polymer materials. The droplet/particle size was varied by changing the flow conditions in the microfluidic device. The diameter of the resulting products typically had a coefficient of variation (CV) below 2%. The specific binding sites that were created during the imprinting process were analysed via radioligand binding analysis. The molecularly imprinted microspheres produced in the liquid perfluorocarbon continuous phase had a higher binding capacity compared with the particles produced in the mineral oil continuous phase, though it should be noted that the aim of this study was not to optimize or maximize imprinting performance, but rather to demonstrate broad applicability and compatibility with known MIP production methods. The successful imprinting against a model compound using two very different continuous phases (one requiring a surfactant to stabilize the droplets the other not) demonstrates the generality of this current simple approach.

  10. Co-loading and intestine-specific delivery of multiple antioxidants in pH-responsive microspheres based on TEMPO-oxidized polysaccharides

    NARCIS (Netherlands)

    Shi, Mengxuan; Bai, Jie; Zhao, Liyun; Yu, Xinrui; Liang, Jingjing; Liu, Ying; Norde, Willem; Li, Yuan

    2017-01-01

    In this study, pH-responsive microspheres loaded with multiple antioxidants were developed for intestine-specific delivery and exhibited synergistic activity. They consist of chitosan (CS)-coated microspheres made of TEMPO-oxidized Konjac glucomannan (OKGM) polymers, of which the carboxyl (COO−)

  11. Development and in-vitro evaluation of sustained-release meclofenamic acid microspheres.

    Science.gov (United States)

    Khidr, S H; Niazy, E M; el-Sayed, Y M

    1998-01-01

    Meclofenamic acid (MFA) sustained-release microspheres were prepared by the solvent evaporation method using cellulose propionate (CP) polymer and acetone as the polymer solvent. Polyethylene glycol (PEG) was used as a channelling agent to improve the release properties of MFA at 1:2:1 drug to polymer to PEG ratio. The microspheres prepared at three different speeds (600, 800 and 1000 rpm) were characterized with regard to their surface morphology, average drug content, particle size distribution and release profiles in phosphate buffer, pH 8.0 at 37 degrees C. The microspheres were stored under accelerated conditions for 3 months and the effect of storage on the different characteristics was studied. Spherical particles with essentially smooth surface and few residual drug crystals on the surface were formed. Smaller particles were formed at higher agitation speeds. The release rate of MFA from these microspheres was not affected by the molecular weight of CP polymer. PEG 2000 was found to have a more enhancing effect on the rate of the release than PEG 4000. The physical properties of the microspheres and their release characteristics were not altered by storing the product at 40 degrees C/80% relative humidity (R.H.) for 3 months.

  12. Biodegradable polylactide microspheres enhance specific immune response induced by Hepatitis B surface antigen.

    Science.gov (United States)

    Qiu, Shaohui; Wei, Qiang; Liang, Zhenglun; Ma, Guanghui; Wang, Lianyan; An, Wenqi; Ma, Xiaowei; Fang, Xin; He, Peng; Li, Hemin; Hu, Zhongyu

    2014-01-01

    Hepatitis B (HB) infection caused by Hepatitis B virus (HBV) is the most common liver disease in the world. HB vaccine, when administered in conjunction with alum adjuvants, induces Th2 immunity that confers protection against HBV. However, currently available vaccine formulations and adjuvants do not elicit adequate Th1 and CTL responses that are important for prevention of maternal transmission of the virus. Microspheres synthesized from poly (D, L-lactide-co-glycolide) (PLGA) or poly (D, L-lactide) (PLA) polymers have been considered as promising tools for in vivo delivery of antigens and drugs. Here we describe PLA microspheres synthesized by premix membrane emulsification method and their application in formulating a new microsphere based HB vaccine. To evaluate the immunogenicity of this microsphere vaccine, BALB/c mice were immunized with microsphere vaccine and a series of immunological assays were conducted. Results of Enzyme-linked ImmunoSpot (ELISPOT) assays revealed that the number of interferon-gamma (IFN-γ)-producing splenocytes and CD8(+) T cells increased significantly in the microsphere vaccine group. Microsphere vaccine group showed enhanced specific cell lysis when compared with HB surface antigen (HBsAg) only group in (51)Cr cytotoxicity assays. Moreover, microsphere vaccine elicited a comparable level of antibody production as that of HB vaccine administered with alum adjuvant. We show that phagocytosis of HBsAg by dendritic cells is more pronounced in microsphere vaccine group when compared with other control groups. These results clearly demonstrate the potential of using PLA microspheres as effective HB vaccine adjuvants for an enhanced Th1 immune response.

  13. Monodisperse microdroplet generation and stopping without coalescence

    Energy Technology Data Exchange (ETDEWEB)

    Beer, Neil Reginald

    2016-02-23

    A system for monodispersed microdroplet generation and trapping including providing a flow channel in a microchip; producing microdroplets in the flow channel, the microdroplets movable in the flow channel; providing carrier fluid in the flow channel using a pump or pressure source; controlling movement of the microdroplets in the flow channel and trapping the microdroplets in a desired location in the flow channel. The system includes a microchip; a flow channel in the microchip; a droplet maker that generates microdroplets, the droplet maker connected to the flow channel; a carrier fluid in the flow channel, the carrier fluid introduced to the flow channel by a source of carrier fluid, the source of carrier fluid including a pump or pressure source; a valve connected to the carrier fluid that controls flow of the carrier fluid and enables trapping of the microdroplets.

  14. Ringing phenomenon in silica microspheres

    Institute of Scientific and Technical Information of China (English)

    Chunhua Dong; Changling Zou; Jinming Cui; Yong Yang; Zhengfu Han; Guangcan Guo

    2009-01-01

    Whispering gallery modes in silica microspheres are excited by a tunable continuous-wave laser through the fiber taper. Ringing phenomenon can be observed with high frequency sweeping speed. The thermal nonlinearity in the microsphere can enhance this phenomenon. Our measurement results agree very well with the theoretical predictions by the dynamic equation.

  15. Biodegradable microsphere-mediated cell perforation in microfluidic channel using femtosecond laser

    Science.gov (United States)

    Ishii, Atsuhiro; Ariyasu, Kazumasa; Mitsuhashi, Tatsuki; Heinemann, Dag; Heisterkamp, Alexander; Terakawa, Mitsuhiro

    2016-05-01

    The use of small particles has expanded the capability of ultrashort pulsed laser optoinjection technology toward simultaneous treatment of multiple cells. The microfluidic platform is one of the attractive systems that has obtained synergy with laser-based technology for cell manipulation, including optoinjection. We have demonstrated the delivery of molecules into suspended-flowing cells in a microfluidic channel by using biodegradable polymer microspheres and a near-infrared femtosecond laser pulse. The use of polylactic-co-glycolic acid microspheres realized not only a higher optoinjection ratio compared to that with polylactic acid microspheres but also avoids optical damage to the microfluidic chip, which is attributable to its higher optical intensity enhancement at the localized spot under a microsphere. Interestingly, optoinjection ratios to nucleus showed a difference for adhered cells and suspended cells. The use of biodegradable polymer microspheres provides high throughput optoinjection; i.e., multiple cells can be treated in a short time, which is promising for various applications in cell analysis, drug delivery, and ex vivo gene transfection to bone marrow cells and stem cells without concerns about residual microspheres.

  16. Study on encapsulation of chlorine dioxide in gelatin microsphere for reducing release rate.

    Science.gov (United States)

    Ci, Ying; Wang, Lin; Guo, Yanchuan; Sun, Ruixue; Wang, Xijie; Li, Jinyou

    2015-01-01

    This study aims to explore the effects of encapsulation of chlorine dioxide in a hydrophilic biodegradable polymer gelatin to reduce its release rate. An emulsification-coacervation method was adopted. The characterizations of chlorine dioxide-gelatin microspheres were described. Using UV-vis spectrophotometer the λmax of chlorine dioxide was observed at 358 nm. The particle size and distribution of chlorine oxide-gelatin microspheres was measured by a dynamic light scattering (DLS) method, the diameter was (1400~1900) nm. The entrapment of chlorine dioxide-gelatin microspheres was confirmed by IR. The surface morphology, size, and shape of chlorine dioxide-gelatin microspheres were analyzed using Scanning electron microscope (SEM). It showed that the encapsulated microspheres size was around 2000 nm with uniform distribution. The percentage entrapment of chlorine dioxide in the encapsulated samples was about 80~85%. A slow release study of chlorine dioxide from the encapsulated biopolymer (gelatin) in air was also carried out, which showed continuous release up to ten days. It can be concluded that it is possible to make a slow release formulation of ClO2 by entrapped in a hydrophilic biodegradable polymer gelatin. ClO2-gelatin microspheres can stable release low concentration ClO2 gas over an extended period.

  17. Formulation and evaluation of albumin microspheres and its enteric coating using a spray-dryer.

    Science.gov (United States)

    Bejugam, Naveen K; Uddin, Akm N; Gayakwad, Sanjay G; D'Souza, Martin J

    2008-12-01

    This study optimized and evaluated the conditions for surface coating of microspheres using a spray-dryer. Four formulations of Bromophenol blue (BPB)-loaded albumin microspheres were prepared using a spray-dryer, cross-linked at different concentrations and time periods. One of the optimized formulations with the desired characteristics was selected for enteric coating with Eudragit L100-55. The procedure involved suspending BPB microspheres in polymer solution and spray-drying it. Four enteric coated formulations were prepared with different concentrations of microspheres in suspension (0.25 and 0.5%w/v) and polymer concentrations (0.25 and 0.5%w/v). Change in the mean particle size after coating was determined using a Laser Particle Counter. The surface coating technique employed did not significantly increase the particle size. Enteric coating efficiency was determined in simulated gastric fluid. Compared to the uncoated microspheres the cumulative amount of drug released from coated microspheres was significantly lower for 3 h, implying efficient surface coating.

  18. Preparation and evaluation of magnetic microspheres of mesalamine (5-aminosalicylic acid) for colon drug delivery

    Institute of Scientific and Technical Information of China (English)

    Satinder Kakar; Deepa Batra; Ramandeep Singh

    2013-01-01

    Objective:To study magnetic microspheres of mesalamine(5-aminosalicylic acid) for colon drug delivery.Methods:Magnetic microspheres were prepared by solvent evaporation technique for use in the application of magnetic carrier technology.An attempt was made to target mesalamine (5-aminosalicylic acid) to its site of action i.e. to colon.EudragitS-100, ethylcellulose and chitosan were used in three different drug: polymer ratios i.e.1:1,1:2 and1:3.The microspheres were characterized in terms of particle size, percentage yield, drug content, encapsulation efficiency,in vitro release pattern andex vivo study.The microspheres were uniform in size and shape.Thein vitrorelease profile was studied in pH7.4 phosphate buffer medium usingUSP dissolution apparatus.Results:Chitosan microspheres were found to be better retained in terms of percentage release of the drug.Thus chitosan microspheres could be better retained at their target site.Conclustion:Flow characteristics are also better in case of chitosan magnetic microspheres. Thus reticuloendothelial clearance can be minimized and site specificity can be increased.

  19. Room-temperature attachment of PLGA microspheres to titanium surfaces for implant-based drug release

    Science.gov (United States)

    Xiao, Dongqin; Liu, Qing; Wang, Dongwei; Xie, Tao; Guo, Tailin; Duan, Ke; Weng, Jie

    2014-08-01

    Drug release from implant surfaces is an effective approach to impart biological activities, (e.g., antimicrobial and osteogenic properties) to bone implants. Coatings of polylactide-based polymer are a candidate for this purpose, but a continuous (fully covering) coating may be non-optimal for implant-bone fixation. This study reports a simple room-temperature method for attaching poly (lactide-co-glycolide) (PLGA) microspheres to titanium (Ti) surfaces. Microspheres were prepared with polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP) as the emulsifier. Microspheres were attached to Ti discs by pipetting as a suspension onto the surfaces followed by vacuum drying. After immersion in shaking water bath for 14 d, a substantial proportion of the microspheres remained attached to the discs. In contrast, if the vacuum-drying procedure was omitted, only a small fraction of the microspheres remained attached to the discs after immersion for only 5 min. Microspheres containing triclosan (a broad-spectrum antibiotic) were attached by porous-surfaced Ti discs. In vitro experiments showed that the microsphere-carrying discs were able to kill Staphylococcus aureus and Escherichia Coli, and support the adhesion and growth of primary rat osteoblasts. This simple method may offer a flexible technique for bone implant-based drug release.

  20. Formulation of mucoadhesive microspheres of rosiglitazone maleate and its in vitro evaluation using ionotropic gelation technique

    Directory of Open Access Journals (Sweden)

    Akanksha Garud

    2015-01-01

    Full Text Available Aim: The objective of the present study is to design and evaluate mucoadhesive microspheres for oral controlled release. Materials and Method: Rosiglitazone maleate microspheres with a coat consisting of alginate and a mucoadhesive polymer sodium carboxymethylcellulose, carbopol 934P and hydroxypropylmethylcellulose were prepared by an orifice-ionic gelation process. The microspheres were evaluated for FTIR studies, morphology, particle size, micromeritic properties, percentage entrapment efficiency, in-vitro wash-off test and in-vitro release studies. Results: The resulting microspheres were spherical and free flowing. The percent entrapment efficiency was 68.2 to 85.6%. The microspheres exhibited good mucoadhesive property in the in vitro wash-off test. Rosiglitazone release from these mucoadhesive microspheres was slow and extended over 12 h duration of time depending on the composition of coat. Conclusions: The prepared mucoadhesive microspheres are thus suitable for oral controlled release of Rosiglitazone maleate and thereby help in the management of type II diabetes mellitus.

  1. Synthesis of novel porous magnetic silica microspheres as adsorbents for isolation of genomic DNA.

    Science.gov (United States)

    Zhang, Zhichao; Zhang, Liming; Chen, Lei; Chen, Ligong; Wan, Qian-Hong

    2006-01-01

    An improved procedure is described for preparation of novel mesoporous microspheres consisting of magnetic nanoparticles homogeneously dispersed in a silica matrix. The method is based on a three-step process, involving (i) formation of hematite/silica composite microspheres by urea-formaldehyde polymerization, (ii) calcination of the composite particles to remove the organic constituents, and (iii) in situ transformation of the iron oxide in the composites by hydrogen reductive reaction. The as-synthesized magnetite/silica composite microspheres were nearly monodisperse, mesoporous, and magnetizable, with as typical values an average diameter of 3.5 microm, a surface area of 250 m(2)/g, a pore size of 6.03 nm, and a saturation magnetization of 9.82 emu/g. These magnetic particles were tested as adsorbents for isolation of genomic DNA from Saccharomyces cerevisiae cells and maize kernels. The results are quite encouraging as the magnetic particle based protocols lead to the extraction of genomic DNA with satisfactory integrity, yield, and purity. Being hydrophilic in nature, the porous magnetic silica microspheres are considered a good alternative to polystyrene-based magnetic particles for use in biomedical applications where nonspecific adsorption of biomolecules is to be minimized.

  2. Study on Synthesis of Polyacrylamide Microspheres and its Sealing Characteristics of Drilling Fluid

    Directory of Open Access Journals (Sweden)

    Mingming Cheng

    2014-02-01

    Full Text Available For the purpose of reducing the invasion depth of solid phase and liquid phase of drilling fluid and improving the quality of drilling mud cake, polyacrylamide microspheres were successfully composed via reversed phrase emulsion method. The physical and chemical structures of the samples as well as the grain-size variation were investigated by Transmission Electron Microscopy (TEM and Laser Particle Size Analysis method (LPSA.The plugging performance of the samples were investigated by core plugging experiment and sand bed filtration experiment. TEM images show that acrylamide has been polymerized, the products consist of a lot of monodisperse microspheres with a size of about 1-6 μm. LPSA images indicate that the particle size of polyacrylamide microspheres vary with time and temperature regularly. The experiment that simulates rock strata with different permeability shows those polyacrylamide microspheres can produce effectively blocked to the core and sand bed and then it establishes the foundation for the next field test.

  3. Multimodal Imaging of Nanocomposite Microspheres for Transcatheter Intra-Arterial Drug Delivery to Liver Tumors

    Science.gov (United States)

    Kim, Dong-Hyun; Li, Weiguo; Chen, Jeane; Zhang, Zhuoli; Green, Richard M.; Huang, Sui; Larson, Andrew C.

    2016-01-01

    A modern multi-functional drug carrier is critically needed to improve the efficacy of image-guided catheter-directed approaches for the treatment of hepatic malignancies. For this purpose, a nanocomposite microsphere platform was developed for selective intra-arterial transcatheter drug delivery to liver tumors. In our study, continuous microfluidic methods were used to fabricate drug-loaded multimodal MRI/CT visible microspheres that included both gold nanorods and magnetic clusters. The resulting hydrophilic, deformable, and non-aggregated microspheres were mono-disperse and roughly 25 um in size. Sustained drug release and strong MRI T2 and CT contrast effects were achieved with the embedded magnetic nano-clusters and radiopaque gold nanorods. The microspheres were successfully infused through catheters selectively placed within the hepatic artery in rodent models and subsequent distribution in the targeted liver tissues and hepatic tumors confirmed with MRI and CT imaging. These multimodal nanocomposite drug carriers should be ideal for selective intra-arterial catheter-directed administration to liver tumors while permitting MRI/CT visualization for patient-specific confirmation of tumor-targeted delivery. PMID:27405824

  4. Preparation of Functional Polymeric Microspheres

    Institute of Scientific and Technical Information of China (English)

    Changchun Wang; Yonghui Deng; Wuli Yang; Shoukuang Fu

    2005-01-01

    @@ 1Introduction Because of the wide applications in the area of biomedical and biotechnological fields, a great efforts have been done to fabricate different kinds of microspheres with tailored structural and surface properties over the last decade[1]. Among them, stimuli responsive microspheres are microspheres that show ability to change their physical-chemical properties and colloidal properties in response to environmental stimuli such as changes of temperature, pH, chemicals, light, electrical field, magnetic field or mechanic stress, etc. These microspheres have been under intensive study for their high potential applications in biomedical and biotechnological fields such as controlled drug delivery[2], biosensor[3], chemical isolation[4], cell culture substrates[5], enzyme immobilization[6], bioelectrocatalysis[7], and magnetically controlled electrochemical reaction[8]. However,most of the reported stimuli responsive microspheres only show response to one specific stimulus. Up to now,to the best of our knowledge, only a few works have been directed to the fabrication of microspheres which show response to more than one stimulus[9]. In this paper, a system synthesis method for stimuli responsive microspheres with more useful properties was reported, and the simple application in biomedical area have been mentioned.

  5. Variations in polyethylene glycol brands and their influence on the preparation process of hydrogel microspheres

    DEFF Research Database (Denmark)

    Wöhl-Bruhn, Stefanie; Bertz, Andreas; Kuntsche, Judith

    2013-01-01

    Hydrogel microspheres, e.g. for the use as protein carriers, can be prepared without the use of organic solvents via an emulsified aqueous two phase system (ATPS) that is based on two immiscible polymer solutions. The type and concentration of the polymers can affect the ATPS and finally the dist......Hydrogel microspheres, e.g. for the use as protein carriers, can be prepared without the use of organic solvents via an emulsified aqueous two phase system (ATPS) that is based on two immiscible polymer solutions. The type and concentration of the polymers can affect the ATPS and finally...... the distribution of incorporated drugs between the aqueous phases. For the preparation of hydrogel microspheres based on hydroxyethyl starch-hydroxyethyl methacrylate (HES-HEMA), hydroxyethyl starch-methacrylate (HES-MA), and hydroxyethyl starch-polyethylene glycol methacrylate (HES-P(EG)6MA), polyethylene glycol...... 12,000 (PEG 12,000) was used as second polymer. The particle size distribution and encapsulation efficiency of the microspheres depended dramatically on the type of PEG 12,000 that was used in the second phase of the ATPS. Analysis of different PEG 12,000 brands by various methods revealed...

  6. Preparation of porous microsphere-scaffolds by electrohydrodynamic forming and thermally induced phase separation

    Energy Technology Data Exchange (ETDEWEB)

    Ghanbar, Hanif; Luo, C.J.; Bakhshi, Poonam [Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE (United Kingdom); Day, Richard [Division of Medicine, University College London, Rockefeller Building, 21 University Street, London, WC1E 6JJ (United Kingdom); Edirisinghe, Mohan, E-mail: m.edirisinghe@ucl.ac.uk [Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE (United Kingdom)

    2013-07-01

    The availability of forming technologies able to mass produce porous polymeric microspheres with diameters ranging from 150 to 300 μm is significant for some biomedical applications where tissue augmentation is required. Moreover, appropriate assembly of microspheres into scaffolds is an important challenge to enable direct usage of the as-formed structures in treatments. This work reports the production of poly (glycolic-co-lactic acid) and poly (ε-caprolactone) microspheres under ambient conditions using one-step electrohydrodynamic jetting (traditionally known as atomisation) and thermally induced phase separation (TIPS). To ensure robust production for practical uses, this work presents 12 comprehensive parametric mode mappings of the diameter distribution profiles of the microspheres obtained over a broad range of key processing parameters and correlating of this with the material parameters of 5 different polymer solutions of various concentrations. Poly (glycolic-co-lactic acid) (PLGA) in Dimethyl carbonate (DMC), a low toxicity solvent with moderate conductivity and low dielectric constant, generated microspheres within the targeted diameter range of 150–300 μm. The fabrication of the microspheres suitable for formation of the scaffold structure is achieved by changing the collection method from distilled water to liquid nitrogen and lyophilisation in a freeze dryer. Highlights: ► EHDA is a unique method for production of the desired size of microspheres. ► Polymer solution properties are used to tailor the size distribution of spheres. ► Process control parameters (flow rate and applied voltage) are key in size control. ► Combination of EHDA with TIPS provides porous microspheres for assembly of scaffold.

  7. Protective colloids and polylactic acid co-affecting the polymorphic crystal forms and crystallinity of indomethacin encapsulated in microspheres.

    Science.gov (United States)

    Lin, S Y; Chen, K S; Teng, H H

    1999-01-01

    The co-effect of protective colloids and polylactic acid (PLA) on the polymorphic crystal forms and crystallinity of indomethacin (IMC) in IMC-loaded PLA microspheres was investigated with differential scanning calorimetry, infrared spectroscopy and x-ray diffractometry, to evaluate the polymorphic crystal forms and crystallinity of IMC encapsulated in PLA microspheres. The surfactant, sodium dodecyl sulphate (SDS), was also used as a dispersing agent. The results indicate that the polymorphism and crystallinity of IMC encapsulated in IMC-loaded PLA microspheres was dependent on the type of protective colloid and PLA used. The amorphous state and alpha-form of IMC were found in the IMC-loaded PLA microspheres prepared using polysaccharide (pectin or beta-cyclodextrin) as a protective colloid or SDS as a dispersing agent. However, the amorphous and methylene chloride solvate of IMC seemed to exist in the IMC-loaded PLA microspheres prepared with the proteins (gelatin or albumin), synthetic cellulose derivative (methyl cellulose or hydroxylpropyl methylcellulose) or the synthetic nonionic polymer (polyvinyl alcohol, polyvinyl pyrrolidone or biosoluble polymer) as a protective colloid. PLA was found to express a certain crystallinity in microspheres and not be affected by the protective colloids, but it played a more important role in influencing the crystallization of IMC during microencapsulation than the protective colloids. No interaction occurred in the physical mixture of IMC and PLA, nor in the IMC-loaded PLA microspheres.

  8. INVESTIGATION OF POLYDL-LACTIDE-b-POLY(ETHYLENE GLYCOL)-b-POLYDL-LACTIDE MICROSPHERES CONTAINING PLASMID DNA

    Institute of Scientific and Technical Information of China (English)

    Yu Liu; Long Huang; Xiao-rong Qiao; Xian-mo Deng; Wen-xiang Jia; Xiao-hong Li

    2004-01-01

    PolyDL-lactide (PDLLA) and the block copolymer, polyDL-lactide-b-poly(ethylene glycol)-b-polyDL-lactide (PELA) were used as the microsphere matrix to encapsulate plasmid DNA. The PDLLA, PELA, pBR322-1oaded PDLLA and pBR322-1oaded PELA microspheres were prepared by solvent extraction method based on the formation of multiple w1/o/w2 emulsion. The microspheres were characterized by surface morphology, mean particle size, particle size distribution and loading efficiency. The integrity of DNA molecules after being extracted from microspheres was determined by agarose gel electrophoresis. The result suggested that plasmid DNA molecules could retain their integrity after being encapsulated by PELA. The PELA microspheres could prevent plasmid DNA from being digested by DNase. The in vitro degradation and release profiles of plasmid DNA-loaded microspheres were measured in pH = 7.4 buffer solution at 37℃. The in vitro degradation profiles of the microspheres were evaluated by the deterioration in microspheres surface morphology, the molecular weight reduction of polymer, the mass loss of microspheres, the changes of pH values of degradation medium, and the changes of particle size. The in vitro release profiles of the microspheres were assessed by measurement of the amount of DNA presented in the release medium at determined intervals. The release profiles were correlation with the degradation profiles. The release of plasmid DNA from PELA microspheres showed a similar biphasic trend, that is, an initial burst release was followed by a slow, but sustained release.

  9. Preparation and Characterization of Titania-grafted Poly(styrene-divinybenzene) Nanocomposite Microspheres

    Institute of Scientific and Technical Information of China (English)

    LI Sen; CHENG Jiang; WANG Kuan; YANG Zhuo-ru

    2008-01-01

    Titania-grafted poly(styrene-divinylbenzene)(TiO2/PSt-DVB) nanocomposite microspheres were prepared by an open-ring reaction and radical grafting copolymerization method. The TiO2 nanoparticles were first modified by attachment of epoxy groups to their surfaces to provide reactive groups that could covalently bond to the polymer (PSt-DVB) microspheres. The nanocomposite obtained was characterized by FTIR, SEM, XRD, and TGA analyses as well as UV-Vis spectrophotometry. The results indicated that the TiO2 nanoparticles were uniformly grafted onto the surface of the polymer microsphere producing grain sizes of about 5-10 μm. The modified TiO2 showed better UV absorbing property than the unmodified form, and the nanocomposite also retained the same UV absorbing property as the free modified TiO2 nanoparticle.

  10. Formulation and evaluation of novel stomach specific floating microspheres bearing famotidine for treatment of gastric ulcer and their radiographic study

    Institute of Scientific and Technical Information of China (English)

    Rishikesh; Gupta; Sunil; Kumar; Prajapati; Snigdha; Pattnaik; Peeyush; Bhardwaj

    2014-01-01

    Objective:To develop and characterize multiple-unit-type oral floating microsphere of famotidine to prolong gastric residence time and to target stomach ulcer.Methods:The floating microspheres were prepared by modified solvent evaporation method,Eudragil S-100 was used as polymer.Microspheres were characterized for the micromeritic properties,floating behavior,entrapment efficiency and scanning electron microscopy.The invitro release studies and floating behavior were studied in simulated gastric fluid at pH 1.2.Different drug release kinetics models were also applied for all the batches.Selected formulations were also subjected for X-ray radiographic study.Results:Floating microspheres were successfully prepared by modified solvent evaporation technique.Microspheres showed passable flow properties.The maximum yield of microspheres was up to(95.11±0.35)%.On the basis of optical microscopy particle size range was found to be ranging from(52.18±182.00) to(91.64±5.16) μm.Scanning electron microscopy showed their spherical size,perforated smooth surface and a cavity inside microspheres.Microspheres were capable to float up to 20 h in simulated gastric fluid.X-ray radiographic studies also proved its better retention in the stomach.Conclusions:On the basis of the results,such dosage forms may be a good candidate for stomach targeting and may be dispensed in hard gelatin capsules.

  11. Formulation and evaluation of novel stomach specific floating microspheres bearing famotidine for treatment of gastric ulcer and their radiographic study

    Institute of Scientific and Technical Information of China (English)

    Rishikesh Gupta; Sunil Kumar Prajapati; Snigdha Pattnaik; Peeyush Bhardwaj

    2014-01-01

    Objective: To develop and characterize multiple-unit-type oral floating microsphere of famotidine to prolong gastric residence time and to target stomach ulcer. Methods: The floating microspheres were prepared by modified solvent evaporation method. Eudragit S-100 was used as polymer. Microspheres were characterized for the micromeritic properties, floating behavior, entrapment efficiency and scanning electron microscopy. The in-vitro release studies and floating behavior were studied in simulated gastric fluid at pH 1.2. Different drug release kinetics models were also applied for all the batches. Selected formulations were also subjected for X-ray radiographic study. Results: Floating microspheres were successfully prepared by modified solvent evaporation technique. Microspheres showed passable flow properties. The maximum yield of microspheres was up to (95.11±0.35)%. On the basis of optical microscopy particle size range was found to be ranging from (52.18±182.00) to (91.64±5.16) µm. Scanning electron microscopy showed their spherical size, perforated smooth surface and a cavity inside microspheres. Microspheres were capable to float up to 20 h in simulated gastric fluid. X-ray radiographic studies also proved its better retention in the stomach. Conclusions:On the basis of the results, such dosage forms may be a good candidate for stomach targeting and may be dispensed in hard gelatin capsules.

  12. Formulation and evaluation of hydroxyzine hydrochloride sustained release microspheres by ionotropic gelation technique using Carbopol 934P

    Directory of Open Access Journals (Sweden)

    Soumyadeep Ghosh

    2014-01-01

    Full Text Available Preparation of sustained release microspheres of hydroxyzine hydrochloride by ionotropic gelation technique and evaluation. Microspheres of hydroxyzine hydrochloride were prepared by ionotropic gelation method using sodium alginate, Carbopol 934P and calcium chloride. The powders were evaluated for their flow properties. Hydroxyzine hydrochloride microspheres were characterized by Fourier transform infrared and in vitro dissolution studies. The drug release study of hydroxyzine hydrochloride microspheres was evaluated using basket type dissolution test apparatus. The release rate of Hydroxyzine hydrochloride microspheres was studied for 12 h in pH 7.4 phosphate buffer media. From the five batches F5 batch showed good release behavior 91.08% of drug is released over 12 h, and r2 = 0.987 in zero-order kinetics. The microspheres were prepared without the use of organic solvents. Microspheres of hydroxyzine hydrochloride decrease the incidence of side effects and also improve patient compliance by reducing the number of dosing and by reducing the fluctuations of drug in the blood. This entire attributed attitude proves that microsphere technology from novel drug delivery can be very much effective in reducing dosage frequency, dose dumping, and better patient compliance and economical to the patient. In the future, natural, biodegradable polymers can be used to improve therapeutic efficacy of the drug and further minimizing side-effects.

  13. Glass microsphere lubrication

    Science.gov (United States)

    Geiger, Michelle; Goode, Henry; Ohanlon, Sean; Pieloch, Stuart; Sorrells, Cindy; Willette, Chris

    1991-01-01

    The harsh lunar environment eliminated the consideration of most lubricants used on earth. Considering that the majority of the surface of the moon consists of sand, the elements that make up this mixture were analyzed. According to previous space missions, a large portion of the moon's surface is made up of fine grained crystalline rock, about 0.02 to 0.05 mm in size. These fine grained particles can be divided into four groups: lunar rock fragments, glasses, agglutinates (rock particles, crystals, or glasses), and fragments of meteorite material (rare). Analysis of the soil obtained from the missions has given chemical compositions of its materials. It is about 53 to 63 percent oxygen, 16 to 22 percent silicon, 10 to 16 percent sulfur, 5 to 9 percent aluminum, and has lesser amounts of magnesium, carbon, and sodium. To be self-supporting, the lubricant must utilize one or more of the above elements. Considering that the element must be easy to extract and readily manipulated, silicon or glass was the most logical choice. Being a ceramic, glass has a high strength and excellent resistance to temperature. The glass would also not contaminate the environment as it comes directly from it. If sand entered a bearing lubricated with grease, the lubricant would eventually fail and the shaft would bind, causing damage to the system. In a bearing lubricated with a solid glass lubricant, sand would be ground up and have little effect on the system. The next issue was what shape to form the glass in. Solid glass spheres was the only logical choice. The strength of the glass and its endurance would be optimal in this form. To behave as an effective lubricant, the diameter of the spheres would have to be very small, on the order of hundreds of microns or less. This would allow smaller clearances between the bearing and the shaft, and less material would be needed. The production of glass microspheres was divided into two parts, production and sorting. Production includes the

  14. A microtensiometer for the analysis of bioadhesive microspheres.

    Science.gov (United States)

    Chickering, D E; Harris, W P; Mathiowitz, E

    1995-01-01

    Bioadhesive polymer microspheres are potential vehicles for the delivery of bioactive agents to mucosal tissues. Bioadhesive delivery devices could improve drug absorption, enhance bioavailability, and increase patient compliance by minimizing dosing regimens. Identification of bioadhesive materials is the first phase in developing bioadhesive drug delivery systems. Additionally, quantification and analysis of the bioadhesive event are essential to successful development of a new generation of adhesive delivery systems. A unique, microbalance-based instrument was developed to analyze bioadhesive forces between polymer microspheres and mucosal tissue segments. A contact angle analyzer, with a custom-made physiologic tissue chamber, was linked to a computer via the serial port. Software was used to modify the microbalance operation to behave as a microtensiometer with a sensitivity of 0.1 microN. After mounting a microsphere and tissue segment in the balance and adjusting the experimental settings, the instrument performs a tensile experiment and automatically determines the following parameters: compressive deformation, peak compressive load, compressive work, yield point, deformation to yield, returned work, peak tensile load, deformation to peak tensile load, fracture strength, deformation to failure, and tensile work. Using this device the authors identified several bioadhesive materials ideally suited for orally-delivered, controlled-release systems. GI-transit studies in rats showed strong correlation between increased GI-residence time and strong bioadhesive interactions.

  15. Effect of colloidal particle size on adsorbed monodisperse and bidisperse monolayers.

    Science.gov (United States)

    Rosenberg, Rachel T; Dan, Nily

    2011-07-19

    Coating hydrogel films or microspheres by an adsorbed colloidal shell is one synthesis method for forming colloidosomes. The colloidal shell allows control of the release rate of encapsulated materials, as well as selective transport. Previous studies found that the packing density of self-assembled, adsorbed colloidal monolayers is independent of the colloidal particle size. In this paper we develop an equilibrium model that correlates the packing density of charged colloidal particles in an adsorbed shell to the particle dimensions in monodisperse and bidisperse systems. In systems where the molar concentration in solution is fixed, the increase in adsorption energy with increasing particle size leads to a monotonic increase in the monolayer packing density with particle radius. However, in systems where the mass fraction of the particles in the adsorbing solutions is fixed, increasing particle size also reduces the molar concentration of particles in solution, thereby reducing the probability of adsorption. The result is a nonmonotonic dependence of the packing density in the adsorbed layer on the particle radius. In bidisperse monolayers composed of two particle sizes, the packing density in the layer increases significantly with size asymmetry. These results may be utilized to design the properties of colloidal shells and coatings to achieve specific properties such as transport rate and selectivity.

  16. Rapid enumeration of phage in monodisperse emulsions.

    Science.gov (United States)

    Tjhung, Katrina F; Burnham, Sean; Anany, Hany; Griffiths, Mansel W; Derda, Ratmir

    2014-06-17

    Phage-based detection assays have been developed for the detection of viable bacteria for applications in clinical diagnosis, monitoring of water quality, and food safety. The majority of these assays deliver a positive readout in the form of newly generated progeny phages by the bacterial host of interest. Progeny phages are often visualized as plaques, or holes, in a lawn of bacteria on an agar-filled Petri dish; however, this rate-limiting step requires up to 12 h of incubation time. We have previously described an amplification of bacteriophages M13 inside droplets of media suspended in perfluorinated oil; a single phage M13 in a droplet yields 10(7) copies in 3-4 h. Here, we describe that encapsulation of reporter phages, both lytic T4-LacZ and nonlytic M13, in monodisperse droplets can also be used for rapid enumeration of phage. Compartmentalization in droplets accelerated the development of the signal from the reporter enzyme; counting of "positive" droplets yields accurate enumeration of phage particles ranging from 10(2) to 10(6) pfu/mL. For enumeration of T4-LacZ phage, the fluorescent signal appeared in as little as 90 min. Unlike bulk assays, quantification in emulsion is robust and insensitive to fluctuations in environmental conditions (e.g., temperature). Power-free emulsification using gravity-driven flow in the absence of syringe pumps and portable fluorescence imaging solutions makes this technology promising for use at the point of care in low-resource environments. This droplet-based phage enumeration method could accelerate and simplify point-of-care detection of the pathogens for which reporter bacteriophages have been developed.

  17. Effects of surface wettability and roughness of microchannel on flow behaviors of thermo-responsive microspheres therein during the phase transition.

    Science.gov (United States)

    Zhou, Ming-Yu; Xie, Rui; Yu, Ya-Lan; Chen, Gang; Ju, Xiao-Jie; Yang, Lihua; Liang, Bin; Chu, Liang-Yin

    2009-08-01

    The flow characteristics of monodisperse thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) microspheres during the phase transition in microchannels with different surface wettabilities and roughnesses are investigated systematically. Glass microchannels are modified by hydroxylation treatment to achieve hydrophilic surface, by self-assembly of chlorotrimethylsilane to realize hydrophobic surface, and by coating with silica nanoparticles to generate rough surface. The phase transition of PNIPAM microspheres in microchannels is induced by local heating. The results show that the surface wettability and roughness of microchannel significantly affect the flow behaviors of PNIPAM microspheres during the phase transition. It is much easier for the PNIPAM microspheres in microchannel with hydrophobic surface to stop right after the phase transition than those in microchannel with hydrophilic surface, and it is also much easier for the PNIPAM microspheres in microchannel with rough surface to stop right after the phase transition than those in microchannel with smooth surface. These results indicate that hydrophobic and rough surface properties of the microchannel can enhance the site-specific targeting of PNIPAM microspheres caused by the phase transition. The results in this study provide valuable information for the application of thermo-responsive drug carriers in site-specific targeting therapy.

  18. Polylactide microspheres prepared by premix membrane emulsification - Effects of solvent removal rate

    NARCIS (Netherlands)

    Sawalha, H.I.M.; Purwanti, N.; Rinzema, A.; Schroën, C.G.P.H.; Boom, R.M.

    2008-01-01

    Polylactide microspheres were prepared by pre-mix membrane emulsification and subsequent extraction of solvent in a coagulation bath, and ultimately to the gas phase. The polymer was dissolved in dichloromethane and emulsified with water or water¿methanol mixtures by repeated passage through a glass

  19. Stimuli-responsive polyaniline coated silica microspheres and their electrorheology

    Science.gov (United States)

    Park, Dae Eun; Choi, Hyoung Jin; Vu, Cuong Manh

    2016-05-01

    Silica/polyaniline (PANI) core-shell structured microspheres were synthesized by coating the surface of silica micro-beads with PANI and applied as a candidate inorganic/polymer composite electrorheological (ER) material. The silica micro-beads were initially modified using N-[(3-trimethoxysilyl)-propyl] aniline to activate an aniline functional group on the silica surface for a better PANI coating. The morphology of the PANI coating on the silica surface was examined by scanning electron microscopy and the silica/PANI core-shell structure was confirmed by transmission electron microscopy. The chemical structure of the particles was confirmed by Fourier transform infrared spectroscopy. Rotational rheometry was performed to confirm the difference in the ER properties between pure silica and silica/PANI microsphere-based ER fluids when dispersed in silicone oil.

  20. Precisely Size-Tunable Monodisperse Hairy Plasmonic Nanoparticles via Amphiphilic Star-Like Block Copolymers.

    Science.gov (United States)

    Chen, Yihuang; Yoon, Young Jun; Pang, Xinchang; He, Yanjie; Jung, Jaehan; Feng, Chaowei; Zhang, Guangzhao; Lin, Zhiqun

    2016-12-01

    In situ precision synthesis of monodisperse hairy plasmonic nanoparticles with tailored dimensions and compositions by capitalizing on amphiphilic star-like diblock copolymers as nanoreactors are reported. Such hairy plasmonic nanoparticles comprise uniform noble metal nanoparticles intimately and perpetually capped by hydrophobic polymer chains (i.e., "hairs") with even length. Interestingly, amphiphilic star-like diblock copolymer nanoreactors retain the spherical shape under reaction conditions, and the diameter of the resulting plasmonic nanoparticles and the thickness of polymer chains situated on the surface of the nanoparticle can be readily and precisely tailored. These hairy nanoparticles can be regarded as hard/soft core/shell nanoparticles. Notably, the polymer "hairs" are directly and permanently tethered to the noble metal nanoparticle surface, thereby preventing the aggregation of nanoparticles and rendering their dissolution in nonpolar solvents and the homogeneous distribution in polymer matrices with long-term stability. This amphiphilic star-like block copolymer nanoreactor-based strategy is viable and robust and conceptually enables the design and synthesis of a rich variety of hairy functional nanoparticles with new horizons for fundamental research on self-assembly and technological applications in plasmonics, catalysis, energy conversion and storage, bioimaging, and biosensors.

  1. Dispersion behavior of core-shell silica-polymer nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Core-shell silica nanoparticles are superior in modifying surface wetting behavior, enhancing nucleation and growth in crystallization, improving dispersion of naked nanoparticles, and thus upgrading the overall properties of organic polymers. The dispersion behavior and morphology of monodisperse core-shell silica particles in several polymers including polyesters are reviewed and their potential applications are discussed.

  2. Fabrication of monodispersive nanoscale alginate–chitosan core–shell particulate systems for controlled release studies

    Energy Technology Data Exchange (ETDEWEB)

    Körpe, Didem Aksoy; Malekghasemi, Soheil; Aydın, Uğur; Duman, Memed, E-mail: memedduman@gmail.com [Hacettepe University, Institute of Science, Nanotechnology and Nanomedicine Division (Turkey)

    2014-12-15

    Biopolymers such as chitosan and alginate are widely used for controlled drug delivery systems. The present work aimed to develop a new protocol for preparation of monodisperse alginate-coated chitosan nanoparticles at nanoscale. Modifications of preparation protocol contain changing the pH of polymer solutions and adding extra centrifugation steps into the procedure. While chitosan nanoparticles were synthesized by ionic gelation method, they were coated with alginate by electrostatic interaction. The size, morphology, charge, and structural characterization of prepared core–shell nanoparticulated system were performed by AFM, Zeta sizer, and FTIR. BSA and DOX were loaded as test biomolecules to core and shell part of the nanoparticle, respectively. Release profiles of BSA and DOX were determined by spectrophotometry. The sizes of both chitosan and alginate-coated chitosan nanoparticles which were prepared by modified protocol were measured to be 50 ± 10 and 60 ± 3 nm, respectively. After loading BSA and DOX, the average size of the particles increased to 80 ± 7 nm. Moreover, while the zeta potential of chitosan nanoparticles was positive value, the value was inverted to negative after alginate coating. Release profile measurements of BSA and DOX were determined during 57 and 2 days, respectively. Our results demonstrated that monodisperse alginate-coated nanoparticles were synthesized and loaded successfully using our modified protocol.

  3. Fabrication of monodispersive nanoscale alginate-chitosan core-shell particulate systems for controlled release studies

    Science.gov (United States)

    Körpe, Didem Aksoy; Malekghasemi, Soheil; Aydın, Uğur; Duman, Memed

    2014-12-01

    Biopolymers such as chitosan and alginate are widely used for controlled drug delivery systems. The present work aimed to develop a new protocol for preparation of monodisperse alginate-coated chitosan nanoparticles at nanoscale. Modifications of preparation protocol contain changing the pH of polymer solutions and adding extra centrifugation steps into the procedure. While chitosan nanoparticles were synthesized by ionic gelation method, they were coated with alginate by electrostatic interaction. The size, morphology, charge, and structural characterization of prepared core-shell nanoparticulated system were performed by AFM, Zeta sizer, and FTIR. BSA and DOX were loaded as test biomolecules to core and shell part of the nanoparticle, respectively. Release profiles of BSA and DOX were determined by spectrophotometry. The sizes of both chitosan and alginate-coated chitosan nanoparticles which were prepared by modified protocol were measured to be 50 ± 10 and 60 ± 3 nm, respectively. After loading BSA and DOX, the average size of the particles increased to 80 ± 7 nm. Moreover, while the zeta potential of chitosan nanoparticles was positive value, the value was inverted to negative after alginate coating. Release profile measurements of BSA and DOX were determined during 57 and 2 days, respectively. Our results demonstrated that monodisperse alginate-coated nanoparticles were synthesized and loaded successfully using our modified protocol.

  4. Microfluidic fabrication of monodisperse polylactide microcapsules with tunable structures through rapid precipitation.

    Science.gov (United States)

    Watanabe, Takaichi; Kimura, Yukitaka; Ono, Tsutomu

    2013-11-19

    We describe a versatile and facile route to the continuous production of monodisperse polylactide (PLA) microcapsules with controllable structures. With the combination of microfluidic emulsification, solvent diffusion, and internal phase separation, uniform PLA microcapsules with a perfluorooctyl bromide (PFOB) core were successfully obtained by simply diluting monodisperse ethyl acetate (EA)-in-water emulsion with pure water. Rapid extraction of EA from the droplets into the aqueous phase enabled the solidification of the polymer droplets in a nonequilibrium state during internal phase separation between a concentrated PLA/EA phase and a PFOB phase. Higher-molecular-weight PLA generated structural complexity of the microcapsules, yielding core-shell microcapsules with covered with small PFOB droplets. Removal of the PFOB via freeze drying gave hollow microcapsules with dimpled surfaces. The core-shell ratios and the diameter of these microcapsules could be finely tuned by just adjusting the concentration of PFOB and flow rates on emulsification, respectively. These biocompatible microcapsules with controllable size and structures are potentially applicable in biomedical fields such as drug delivery carriers of many functional molecules.

  5. Phase separation behavior of fusidic acid and rifampicin in PLGA microspheres.

    Science.gov (United States)

    Gilchrist, Samuel E; Rickard, Deborah L; Letchford, Kevin; Needham, David; Burt, Helen M

    2012-05-01

    The purpose of this study was to characterize the phase separation behavior of fusidic acid (FA) and rifampicin (RIF) in poly(d,l-lactic acid-co-glycolic acid) (PLGA) using a model microsphere formulation. To accomplish this, microspheres containing 20% FA with 0%, 5%, 10%, 20%, and 30% RIF and 20% RIF with 30%, 20% 10%, 5%, and 0% FA were prepared by solvent evaporation. Drug-polymer and drug-drug compatibility and miscibility were characterized using laser confocal microscopy, Raman spectroscopy, XRPD, DSC, and real-time video recordings of single-microsphere formation. The encapsulation of FA and RIF alone, or in combination, results in a liquid-liquid phase separation of solvent-and-drug-rich microdomains that are excluded from the polymer bulk during microsphere hardening, resulting in amorphous spherical drug-rich domains within the polymer bulk and on the microsphere surface. FA and RIF phase separate from PLGA at relative droplet volumes of 0.311 ± 0.014 and 0.194 ± 0.000, respectively, predictive of the incompatibility of each drug and PLGA. When coloaded, FA and RIF phase separate in a single event at the relative droplet volume 0.251 ± 0.002, intermediate between each of the monoloaded formulations and dependent on the relative contribution of FA or RIF. The release of FA and RIF from phase-separated microspheres was characterized exclusively by a burst release and was dependent on the phase exclusion of surface drug-rich domains. Phase separation results in coalescence of drug-rich microdroplets and polymer phase exclusion, and it is dependent on the compatibility between FA and RIF and PLGA. FA and RIF are mutually miscible in all proportions as an amorphous glass, and they phase separate from the polymer as such. These drug-rich domains were excluded to the surface of the microspheres, and subsequent release of both drugs from the microspheres was rapid and reflected this surface location.

  6. In vitro and In vivo assessment of lawsone microsphere loaded chitosan scaffolds

    Directory of Open Access Journals (Sweden)

    Jamal Basha D

    2016-09-01

    Full Text Available Objective: To prepare, assess the lawsone loaded chitosan scaffolds for antibacterial and wound healing activity.Methods: The work was focused is to develop a topical formulation preferably, natural biodegradable scaffolds of lawsone drug for treating skin wounds and bacterial infections. Here, lawsone loaded chitosan microspheres were impregnated into chitosan scaffolds. The lawsone microspheres prepared by emulsification and cross linking method. Incorporation of lawsone loaded chitosan microspheres into chitosan scaffolds by emulsification and freeze drying technique. The lawsone a microspheres characterized by FT-IR, SEM, evaluated through entrapment efficiency, percentage yield, in vitro drug release studies. Lawsone scaffolds was assessed for wound healing ability using albino rats and anti bacterial activity by agar disc diffusion method.Results: the FT-IR spectra showing almost similar peaks within the same wave length range indicating the there is no possible interaction between the drug and polymer. The SEM of Lawsone microspheres and prepared scaffolds showing oval shape, slightly rough, porous surface, slightly aggregated and interconnected porous structure of the scaffolds was slightly reddish brown in colour. The lawsone loaded chitosan scaffolds had exhibited antibacterial activity against different bacrial strains and wound healing potential in albino rats.Conclusion:  The schematic process of lawsone loaded chitosan microspheres imparts quality in the in the topical formulation and obtained results were judicious.

  7. Intestine-Specific Delivery of Hydrophobic Bioactives from Oxidized Starch Microspheres with an Enhanced Stability.

    Science.gov (United States)

    Wang, Shanshan; Chen, Yuying; Liang, Hao; Chen, Yiming; Shi, Mengxuan; Wu, Jiande; Liu, Xianwu; Li, Zuseng; Liu, Bin; Yuan, Qipeng; Li, Yuan

    2015-10-01

    An intestine-specific delivery system for hydrophobic bioactives with improved stability was developed. It consists of oxidized potato starch polymers, where the carboxyl groups were physically cross-linked via ferric ions. The model hydrophobic ingredients (β-carotene) were incorporated inside the starch microspheres via a double-emulsion method. Confocal laser scanning microscopy images showed that β-carotene were distributed homogeneously in the inner oil phase of the starch microspheres. The negative value of the ζ-potential of microspheres increased with increasing pH and decreasing ionic strength. In vitro release experiments showed that the microspheres were stable at acidic stomach conditions (pH intestinal conditions (pH 7.0), they rupture to release the loaded β-carotene. The 1,1-diphenyl-2-picrylhydrazyl radical, 2,2-diphenyl-1-(2,4,6-trinitriphenyl), scavenging activity results suggested that microsphere-encapsulated β-carotene had an improved activity after thermal treatment at 80 °C. The storage stability of encapsulated β-carotene at room temperature was also enhanced. The starch microspheres showed potential as intestine-specific carriers with an enhanced stability.

  8. Fabrication of chitin microspheres and their multipurpose application as catalyst support and adsorbent.

    Science.gov (United States)

    Wang, Yuntao; Li, Yan; Liu, Shilin; Li, Bin

    2015-04-20

    In this study, novel chitin microspheres (CM) with diameters of 1010 μm, 750 μm, 490 μm, 280 μm were fabricated by employing the sol-gel transition method. Then the chitin microspheres served as the enabling platform for a range of applications including recyclable catalyst support and adsorbent. First, the freeze dried porous chitin microspheres were coated with dopamine to enhance the loading efficiency of a model biomacromolecule, α-amylase. The immobilized enzyme (49.6 mg/g) retained more than 95% of relative activity after 10 repeated cycles and exhibited easy recovery ability. Then porous magnetic chitin microspheres could be prepared, and the swollen porous polymer successfully controlled the growth of gold nanoparticles. The chitin/Au nanocomposite microspheres were a good recyclable catalyst due to the porous structure and a reduced dimension of the metal particles (r ≤ 5 nm). Finally, the magnetic chitin microspheres were modified into an adsorbent for enhanced removal of a typical cationic compound, methylene blue from aqueous solution. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Eudragit-coated aceclofenac-loaded pectin microspheres in chronopharmacological treatment of rheumatoid arthritis.

    Science.gov (United States)

    Ramasamy, Thiruganesh; Ruttala, Hima Bindu; Shanmugam, Suresh; Umadevi, Subbiah Kandasamy

    2013-02-01

    The aim of this study was to develop a pectin-based colon-specific multiparticulate delivery system. Aceclofenac was used as a model drug owing to its potential therapeutic efficacy in rheumatoid arthritis. Pectin microspheres were prepared using emulsion dehydration technique. These microspheres were coated with Eudragit S-100 using solvent evaporation method. The effect of different variables (polymer, emulsifier, stirring speed and stirring time) was investigated in terms of size, surface morphology, entrapment efficiency, in vitro release and in vivo studies. The size of uncoated microspheres ranged from 30 to 55 µm and exhibited 5-40% of drug release in the upper gastrointestinal tract; however, continuous high release of drug was observed at colonic pH. In addition, the release of drug from the microspheres was found to be higher in the presence of rat cecal contents with maximum release at the 8th hour. This is one of the prerequisites for the effective treatment of rheumatoid arthritis, indicating the effect of colonic enzymes on the pectin microspheres. In vivo studies suggest the maintenance of therapeutic concentration of drug for 24 h with significant anti-inflammatory effect. Therefore, these findings clearly suggest that the Eudragit-coated pectin microspheres offer an exciting mode of aceclofenac delivery to colon in the chronopharmacological treatment of rheumatoid arthritis.

  10. Thermo-sensitive gels containing lorazepam microspheres for intranasal brain targeting.

    Science.gov (United States)

    Jose, S; Ansa, C R; Cinu, T A; Chacko, A J; Aleykutty, N A; Ferreira, S V; Souto, E B

    2013-01-30

    Thermo-sensitive gels containing lorazepam microspheres were developed and characterized for intranasal brain targeting. Pluronics (PF-127 and PF-68) have been selected since they are thermo-reversible polymers with the property of forming a solution at low temperatures (4-5 °C), and a gel at body temperature (37 °C). This property makes them an interesting material to work with, especially in case of controlled release formulations. The present study focuses on the development of an intranasal formulation for lorazepam, as an alternative route of drug delivery to the brain. Direct transport of drugs to the brain circumventing the brain barrier, following intranasal administration, provides a unique feature and better option to target brain. The presence of mucoadhesive microspheres in the gel vehicle via nasal route can achieve a dual purpose of prolonged drug release and enhanced bioavailability. To optimise the microsphere formulation, Box Behnken design was employed by investigating the effect of three factors, polymer concentration (chitosan), emulsifier concentration (Span 80) and cross-linking agent (glutaraldehyde) on the response variable which is the mean particle size. The concentration of 21% PF-127 and 1% PF-68 were found to be promising gel vehicles. The results showed that the release rate followed a prolonged profile dispersion of the microspheres in the viscous media, in comparison to the microspheres alone. Histopathological studies proved that the optimised formulation does not produce any toxic effect on the microscopic structure of nasal mucosa.

  11. Statistical optimization of controlled release microspheres containing cetirizine hydrochloride as a model for water soluble drugs.

    Science.gov (United States)

    El-Say, Khalid M; El-Helw, Abdel-Rahim M; Ahmed, Osama A A; Hosny, Khaled M; Ahmed, Tarek A; Kharshoum, Rasha M; Fahmy, Usama A; Alsawahli, Majed

    2015-01-01

    The purpose was to improve the encapsulation efficiency of cetirizine hydrochloride (CTZ) microspheres as a model for water soluble drugs and control its release by applying response surface methodology. A 3(3) Box-Behnken design was used to determine the effect of drug/polymer ratio (X1), surfactant concentration (X2) and stirring speed (X3), on the mean particle size (Y1), percentage encapsulation efficiency (Y2) and cumulative percent drug released for 12 h (Y3). Emulsion solvent evaporation (ESE) technique was applied utilizing Eudragit RS100 as coating polymer and span 80 as surfactant. All formulations were evaluated for micromeritic properties and morphologically characterized by scanning electron microscopy (SEM). The relative bioavailability of the optimized microspheres was compared with CTZ marketed product after oral administration on healthy human volunteers using a double blind, randomized, cross-over design. The results revealed that the mean particle sizes of the microspheres ranged from 62 to 348 µm and the efficiency of entrapment ranged from 36.3% to 70.1%. The optimized CTZ microspheres exhibited a slow and controlled release over 12 h. The pharmacokinetic data of optimized CTZ microspheres showed prolonged tmax, decreased Cmax and AUC0-∞ value of 3309 ± 211 ng h/ml indicating improved relative bioavailability by 169.4% compared with marketed tablets.

  12. Self-assembly of CdSe quantum dots and colloidal titanium dioxide on copolymer microspheres (PS) for CdSe/PS and TiO{sub 2}/CdSe/PS sub-microspheres with yolk–shell structure

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Qingchun, E-mail: qczhao@ustc.edu

    2015-07-30

    Highlights: • CdSe/PS sub-microspheres composite were prepared via self-assembly of CdSe quantum dots on modified PS surface. • TiO{sub 2}/CdSe/PS sub-microspheres were prepared via self-assembly of colloidal titanium dioxide on CdSe/PS sub-microspheres surface. • TiO{sub 2}/CdSe/PS sub-microspheres with yolk–shell structure. • TiO{sub 2}/CdSe/PS sub-microspheres with yolk–shell structure can improve the efficiency of charge separation. - Abstract: Semiconductor nanocrystals serve as the building blocks for designing next generation solar cells, chemical/biological sensors, and metal chalcogenides (e.g., CdS, CdSe, PbS, and PbSe) are particularly useful for harnessing size-dependent optical and electronic properties in nanostructures. In this paper, relying on the interaction including van der Waals forces and hydrogen bond, CdSe/PS sub-microspheres composite and TiO{sub 2}/CdSe/PS sub-microspheres with yolk–shell structure were prepared via self-assembly of CdSe quantum dots and colloidal titanium dioxide on modified PS surface. The morphology, structure and composition obtained products were investigated by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and energy disperse X-ray spectroscopy (EDX). Transmission electron microscopy (TEM) investigations show the CdSe quantum dots and colloidal titanate were assembled on the surface of PS sub-microspheres. CdSe QD-polymer sub-microspheres composites in which the QDs retain their original emission efficiency can be obtained. TiO{sub 2}/CdSe/PS sub-microspheres with yolk–shell structure can improve the efficiency of charge separation.

  13. Design and evaluation of controlled release mucoadhesive microspheres of amoxicillin for anti Helicobacter pylori therapy

    Directory of Open Access Journals (Sweden)

    N Venkateswaramurthy

    2011-01-01

    Full Text Available The aim of this study was to develop controlled release mucoadhesive microspheres of amoxicillin trihydrate for the treatment of peptic ulcer disease caused by Helicobacter pylori (H. pylori. Microspheres were prepared by solvent evaporation technique using carbopol 974P, hydroxypropyl methyl cellulose K4M (HPMC K4M and Eudragit RS 100. The prepared microspheres were subjected to evaluation for particle size, incorporation efficiency, in vitro mucoadhesion and in vitro drug release characteristics. Absence of drug-polymer interaction was confirmed using differential scanning calorimetry analysis and fourier transform infrared spectrophotometry. The prepared microspheres showed a strong mucoadhesive property. The polymer concentration influenced the in vitro drug release significantly in 0.1N HCl. The particle sizes of systems ranged between 123±8.35 μm and 524±11.54 μm. Percent drug entrapment and release profiles of amoxicillin trihydrate in 0.1 N HCl were determined using high-performance liquid chromatography. The percentage drug entrapment and percentage yield of formulations were about 56.71±1.66% to 88.32±0.65% and 39.20±1.62% to 92.40±1.32%, respectively. The stability of the drugs was assessed in 0.1 N HCl. The results further substantiated that mucoadhesive microspheres improved the gastric stability of amoxicillin trihydrate (due to entrapment within the microsphere. From the above results, it was concluded that the mucoadhesive microspheres of amoxicillin trihydrate has feasibility for eradicating H. pylori from the stomach more effectively because of the prolonged gastrointestinal residence time and controlled release of drug from the formulation.

  14. Microspheres and their methods of preparation

    Science.gov (United States)

    Bose, Anima B; Yang, Junbing

    2015-03-24

    Carbon microspheres are doped with boron to enhance the electrical and physical properties of the microspheres. The boron-doped carbon microspheres are formed by a CVD process in which a catalyst, carbon source and boron source are evaporated, heated and deposited onto an inert substrate.

  15. Enhanced Degradation of Lactide-co-Glycolide Polymer with Basic Nucleophilic Drugs

    Directory of Open Access Journals (Sweden)

    Susan D’Souza

    2015-01-01

    Full Text Available The purpose of this study was to examine the degradative effect of weakly basic nucleophilic drugs on a lactide-co-glycolide (PLGA polymer in a microsphere formulation. Biodegradable PLGA microspheres of two second-generation atypical antipsychotics, Risperidone and Olanzapine, were manufactured using a solvent extraction/evaporation technique. The effect of drug content, buffer pH and temperature on polymer molecular weight and degradation, were examined via a series of experiments and compared against a control (Placebo PLGA microspheres. In comparison to Placebo microspheres, significant polymer molecular weight reduction was observed upon encapsulation of varying levels of either Risperidone or Olanzapine. There was excellent correlation between the extent of molecular weight reduction during manufacture and the amount of encapsulated drug in the microspheres. Subsequent studies on polymer degradation showed: the following (a the Placebo and Olanzapine microspheres followed pseudo first order kinetics, (b Risperidone microspheres exhibited biphasic degradation profiles, and (c polymer degradation was dependent on temperature, not pH. The findings of these studies show that encapsulation of weakly basic nucleophile type drugs into PLGA can accelerate the biodegradation of the PLGA and have major implications on the design of polymeric microsphere drug delivery systems.

  16. Molecularly imprinted shells from polymer and xerogel matrices on polystyrene colloidal spheres.

    Science.gov (United States)

    Guan, Guijian; Liu, Renyong; Mei, Qingsong; Zhang, Zhongping

    2012-04-10

    We have devised a facile and general methodology for the synthesis of various molecularly imprinted shells at the surface of polystyrene (PS) colloidal spheres to recognize the explosive compound 2,4,6-trinitrotoluene (TNT). PS spheres with surface-functionalized carboxyl-group layers could direct a selective imprinting polymerization on their surface through the hydrogen-bonding interactions between surface carboxyl groups and amino monomers. Meanwhile, homogeneous polymerization in the solution phase was completely prevented by stepwise polymerization. The overall process led to the formation of monodisperse molecularly imprinted core-shell microspheres, and was very successful in the preparation of organic polymer and inorganic xerogel shells. Furthermore, greater capacity and faster binding kinetics towards target species were achieved, because surface-imprinted sites ensured the complete removal of templates, good accessibility to target molecules, and low mass-transfer resistance. The results reported herein, concerning the production of high-quality molecularly imprinted products, could also form the basis for the formulation of a new strategy for the fabrication of various functional coating layers on colloidal spheres with potential applications in the fields of separations and chemical sensing.

  17. Floating microspheres: a review

    Directory of Open Access Journals (Sweden)

    Jagtap Yogesh Mukund

    2012-03-01

    Full Text Available Gastric emptying is a complex process, one that is highly variable and that makes in vivo performance of drug delivery systems uncertain. A controlled drug delivery system with prolonged residence time in the stomach can be of great practical importance for drugs with an absorption window in the upper small intestine. The main limitations are attributed to the inter- and intra-subject variability of gastro-intestinal (GI transit time and to the non-uniformity of drug absorption throughout the alimentary canal. Floating or hydrodynamically controlled drug delivery systems are useful in such applications. Various gastroretentive dosage forms are available, including tablets, capsules, pills, laminated films, floating microspheres, granules and powders. Floating microspheres have been gaining attention due to the uniform distribution of these multiple-unit dosage forms in the stomach, which results in more reproducible drug absorption and reduced risk of local irritation. Such systems have more advantages over the single-unit dosage forms. The present review briefly addresses the physiology of the gastric emptying process with respect to floating drug delivery systems. The purpose of this review is to bring together the recent literature with respect to the method of preparation, and various parameters affecting the performance and characterization of floating microspheres.O esvaziamento gástrico é um processo complexo, com elevada variabilidade e responsável pela incerteza do desempenho dos medicamentos in vivo. Dessa forma, os sistemas de liberação modificada de fármacos, com tempo de residência prolongado no estômago, em especial, considerando aqueles fármacos com janela de absorção na porção superior do intestino delgado, apresentam fundamental importância. As principais limitações relativas à absorção do fármaco são, no geral, atribuídas à variabilidade inter e intra-paciente do tempo de trânsito gastro-intestinal (GI e

  18. Encapsulation of azithromycin into polymeric microspheres by reduced pressure-solvent evaporation method.

    Science.gov (United States)

    Li, Xiujuan; Chang, Si; Du, Guangsheng; Li, Yi; Gong, Junbo; Yang, Mingshi; Wei, Zhenping

    2012-08-20

    Azithromycin loaded microspheres with blends of poly-l-lactide and ploy-D,L-lactide-co-glycolide as matrices were prepared by the atmosphere-solvent evaporation (ASE) and reduced pressure-solvent evaporation (RSE) method. Both the X-ray diffraction spectra and DSC thermographs demonstrated that poly-L-lactide existed in a crystalline form in the ASE microspheres, while an amorphous form was present in the RSE formulations. Besides, solvent removal at atmosphere gave microspheres of porous and rough surfaces, but smooth surfaces appeared in the RSE microspheres. The incorporation efficiency as well as the burst release (cumulative release in the first 24h) in the ASE formulations was 39.94 ± 1.18% and 23.96 ± 2.01% respectively, yet the encapsulation efficiency of the microspheres fabricated under 385 mmHg was high up to 57.19 ± 3.81% and the burst release was 4.12 ± 0.15%. The in vitro drug release studies indicated that the ASE microspheres presented a zero-order profile; while the RSE formulations followed first-order kinetics. Other factors including solidification time, temperature, drug to polymer ratio and pH value of the continuous phase could also influence the physicochemical characteristics and release profiles of microspheres. In conclusion, the overall improvement of microspheres in appearance, encapsulation efficiency and controlled drug release through the RSE method could be easily fulfilled under optimal preparation conditions. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Hollow glass microspheres for temperature and irradiance control in photobioreactors.

    Science.gov (United States)

    Pereira, Darlan A; José, Nadia M; Villamizar, Sonia M G; Sales, Emerson A; Perelo, Louisa W

    2014-04-01

    The addition of hollow glass microspheres (HGM) to polymers to change thermal insulation and mechanical properties is widely used. In this study HGM were tested as a new construction material for photobioreactors to control irradiance and broth temperature in microalgae cultivation. The heat isolation properties of HGMs of three different densities were tested in a polymer matrix. The transmittance (5-50%) and the thermal conductivity (182.05-190.73 W/mK) of the HGM composite material were analyzed. The results were tested in a model to predict the broth temperature and the growth rate as a function of temperature and irradiance. The addition of 1.3 and 0.6 vol.% of HGM lead to an increase in the growth rate of up to 37% and a reduction in the broth temperature up to 9°C. The mechanical resistance of the composites tested is similar to the polymer matrix.

  20. Catastrophic failure of polymer melts during extension

    DEFF Research Database (Denmark)

    Rasmussen, Henrik K.

    2013-01-01

    Numerical flow modeling has been applied to study the break of monodisperse polymer melts during extension. These continuum mechanical based computations are within the ideas of the microstructural ’interchain pressure’ theory. Calculated breaks, a result of small initial sample imperfections, ag...

  1. Advances in Microsphere Insulation Systems

    Science.gov (United States)

    Allen, M. S.; Baumgartner, R. G.; Fesmire, J. E.; Augustynowicz, S. D.

    2004-06-01

    Microsphere insulation, typically consisting of hollow glass bubbles, combines in a single material the desirable properties that other insulations only have individually. The material has high crush strength, low density, is noncombustible, and performs well in soft vacuum. Microspheres provide robust, low-maintenance insulation systems for cryogenic transfer lines and dewars. They also do not suffer from compaction problems typical of perlite that result in the necessity to reinsulate dewars because of degraded thermal performance and potential damage to its support system. Since microspheres are load bearing, autonomous insulation panels enveloped with lightweight vacuum-barrier materials can be created. Comprehensive testing performed at the Cryogenics Test Laboratory located at the NASA Kennedy Space Center demonstrated competitive thermal performance with other bulk materials. Test conditions were representative of actual-use conditions and included cold vacuum pressure ranging from high vacuum to no vacuum and compression loads from 0 to 20 psi. While microspheres have been recognized as a legitimate insulation material for decades, actual implementation has not been pursued. Innovative microsphere insulation system configurations and applications are evaluated.

  2. Optical trapping of coated microspheres.

    Science.gov (United States)

    Bormuth, Volker; Jannasch, Anita; Ander, Marcel; van Kats, Carlos M; van Blaaderen, Alfons; Howard, Jonathon; Schäffer, Erik

    2008-09-01

    In an optical trap, micron-sized dielectric particles are held by a tightly focused laser beam. The optical force on the particle is composed of an attractive gradient force and a destabilizing scattering force. We hypothesized that using anti-reflection-coated microspheres would reduce scattering and lead to stronger trapping. We found that homogeneous silica and polystyrene microspheres had a sharp maximum trap stiffness at a diameter of around 800 nm--the trapping laser wavelength in water--and that a silica coating on a polystyrene microsphere was a substantial improvement for larger diameters. In addition, we noticed that homogeneous spheres of a correct size demonstrated anti-reflective properties. Our results quantitatively agreed with Mie scattering calculations and serve as a proof of principle. We used a DNA stretching experiment to confirm the large linear range in detection and force of the coated microspheres and performed a high-force motor protein assay. These measurements show that the surfaces of the coated microspheres are compatible with biophysical assays.

  3. Preparation of molecularly imprinted polymers using theanine as dummy template and its application as SPE sorbent for the determination of eighteen amino acids in tobacco.

    Science.gov (United States)

    Zhu, Fengling; Wang, Jing; Zhu, Lijun; Tan, Lanlan; Feng, Guanglin; Liu, Shaomin; Dai, Ya; Wang, Hua

    2016-04-01

    In this paper, a novel dummy template molecularly imprinted polymer (DMIP) based on a vinyl-SiO2 microspheres surface for the simultaneous selective recognition and enrichment of 18 amino acids was prepared via a surface molecular imprinting technique using theanine as a dummy template. Compared to the imprinted polymers prepared using traditional polymerization techniques, the obtained DMIPs exhibited a regular spherical shape and were relatively monodisperse. The maximal sorption capacity (Qmax) of the resulting DMIPs for the 18 amino acids was up to 1444.3 mg g(-1). A kinetic binding study showed that the sorption capacity reached 85.40% of Qmax in 25 min and sorption equilibrium at 30 min. The imprint factors of the sorbents ranged from 2.86 to 6.9 for the 18 amino acids, which indicated that the DMIP sorbents have high selectivity. An HPLC-UV method for the simultaneous determination of 18 amino acids in tobacco and tobacco smoke was developed using the DMIPs as sorbents for solid phase extraction (SPE) in the sample pretreatment procedure. Under the optimum experimental conditions, the materials had enrichment factors of up to 200 for the amino acids, and the recoveries of the 18 amino acids in tobacco smoke were in the range from 79% to 104% with relative standard deviations of less than 7.4%. It indicated that the obtained DMIP sorbents could specifically recognize the amino acids from complicated samples.

  4. Polarization Dependent Whispering Gallery Modes in Microspheres

    Science.gov (United States)

    Adamovsky, Grigory (Inventor); Wrbanek, Susan Y. (Inventor)

    2016-01-01

    A tunable resonant system is provided and includes a microsphere that receives an incident portion of a light beam generated via a light source, the light beam having a fundamental mode, a waveguide medium that transmits the light beam from the light source to the microsphere, and a polarizer disposed in a path of the waveguide between the light source and the microsphere. The incident portion of the light beam creates a fundamental resonance inside the microsphere. A change in a normalized frequency of the wavelength creates a secondary mode in the waveguide and the secondary mode creates a secondary resonance inside the microsphere.

  5. Porous microsphere and its applications

    Directory of Open Access Journals (Sweden)

    Cai Y

    2013-03-01

    Full Text Available Yunpeng Cai,1,2* Yinghui Chen,3* Xiaoyun Hong,2 Zhenguo Liu,1 Weien Yuan2 1Department of Neurology, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, 2School of Pharmacy, Shanghai JiaoTong University, 3Department of Neurology Jinshan Hospital, Fudan University, Shanghai, People's Republic of China *These authors contributed equally to this workAbstract: Porous microspheres have drawn great attention in the last two decades for their potential applications in many fields, such as carriers for drugs, absorption and desorption of substances, pulmonary drug delivery, and tissue regeneration. The application of porous microspheres has become a feasible way to address existing problems. In this essay, we give a brief introduction of the porous microsphere, its characteristics, preparation methods, applications, and a brief summary of existing problems and research tendencies.Keywords: pore, porosity, porogen, suspension polymerization, seed swelling, pulmonary drug delivery, tissue regeneration

  6. Spontaneous droplet formation techniques for monodisperse emulsions preparation – Perspectives for food applications

    NARCIS (Netherlands)

    Maan, A.A.; Schroën, C.G.P.H.; Boom, R.M.

    2011-01-01

    Spontaneous droplet formation through Laplace pressure differences is a simple method for making monodisperse emulsions and is claimed to be suited for shear and temperature sensitive products, and those requiring high monodispersity. Techniques belonging to this category include (grooved) microchan

  7. Observation of thermally induced tuning of lasing emission from melamine–formaldehyde resin microspheres

    Science.gov (United States)

    Li, Hanyang; Liu, Shuangqiang; Peng, Feng; Yang, Jun; Li, Jin; Zhang, Yundong

    2017-03-01

    We report on the observation of the thermally induced tuning of the whispering gallery mode lasing emission from active microcavities. Melamine–formaldehyde resin microspheres were doped with a fluorescent dye and pumped by a 532 nm pulse laser. We show that microspheres with different sizes display lasing emissions in different parts of the spectrum, with a varying number of lasing modes present in the spectrum. The dominant thermo-optic effect leads to a blue shift of the whispering gallery mode lasing. The thermal sensing with a sensitivity of 0.33 nm/°C is higher than that of conventional polymer microcavities.

  8. Manufacture of poly(methyl methacrylate) microspheres using membrane emulsification.

    Science.gov (United States)

    Bux, Jaiyana; Manga, Mohamed S; Hunter, Timothy N; Biggs, Simon

    2016-07-28

    Accurate control of particle size at relatively narrow polydispersity remains a key challenge in the production of synthetic polymer particles at scale. A cross-flow membrane emulsification (XME) technique was used here in the preparation of poly(methyl methacrylate) microspheres at a 1-10 l h(-1) scale, to demonstrate its application for such a manufacturing challenge. XME technology has previously been shown to provide good control over emulsion droplet sizes with careful choice of the operating conditions. We demonstrate here that, for an appropriate formulation, equivalent control can be gained for a precursor emulsion in a batch suspension polymerization process. We report here the influence of key parameters on the emulsification process; we also demonstrate the close correlation in size between the precursor emulsion and the final polymer particles. Two types of polymer particle were produced in this work: a solid microsphere and an oil-filled matrix microcapsule.This article is part of the themed issue 'Soft interfacial materials: from fundamentals to formulation'.

  9. Formulation and evaluation of clarithromycin microspheres for eradication of Helicobacter pylori.

    Science.gov (United States)

    Rajinikanth, Paruvathanahalli Siddalingam; Karunagaran, Lakshmi Narayanan; Balasubramaniam, Jagdish; Mishra, Brahmeshwar

    2008-12-01

    The objective of the study was to develop a stomach-specific drug delivery system for controlled release of clarithromycin for eradication of Helicobacter pylori (H. pylori). Floating-bioadhesive microspheres of clarithromycin (FBMC) were prepared by emulsification-solvent evaporation method using ethylcellulose as matrix polymer and Carbopol 934P as mucoadhesive polymer. The prepared microspheres were subjected to evaluation for particle size, incorporation efficiency, in vitro buoyancy, in vitro mucoadhesion and in vitro drug release characteristics. The prepared microspheres showed a strong mucoadhesive property with good buoyancy. The formulation variables like polymer concentration and drug concentration influenced the in vitro drug release significantly in simulated gastric fluid (pH. 2.0). The in vivo H. pylori clearance efficiency of prepared FBMC in reference to clarithromycin suspension following repeated oral administration to H. pylori infected Mongolian gerbils was examined by polymerase chain reaction (PCR) technique and by a microbial culture method. The FBMC showed a significant anti-H. pylori effect in the in vivo gerbil model. It was also noted that the required amount of clarithromycin for eradication of H. pylori was significantly less in FBMC than from corresponding clarithromycin suspension. The results further substantiated that FBMC improved the gastric stability of clarithromycin (due to entrapment within the microsphere) and eradicated H. pylori from the gastrointestinal tract more effectively than clarithromycin suspension because of the prolonged gastrointestinal residence time of the formulation.

  10. [Preparation and application of solid phase extraction packing of zirconia microsphere coated with sulfonated crosslinked polystyrene].

    Science.gov (United States)

    Shen, Shuchang; Liu, Yuhui; Xiao, Xiaoxing

    2013-08-01

    Zirconia microsphere was prepared by polymerization-induced colloid aggregation (PICA) method and carbon-carbon double bond was grafted onto its surface by titanic acid ester coupling reagent. Poly(styrene-divinylbenzene) was synthesized by free radical polymerization by using styrene, divinylbenzene and carbon-carbon double bond on the microsphere surface in solution system, so the polymer was coated on the microsphere surface. After the benzene ring of the polymer was sulfonated, the cation exchange packing for solid phase extraction (SPE) was obtained. The material was characterized by Fourier transform infrared spectroscopy, scanning electron microscope and X-ray energy dispersive spectroscopy. Three herbicides of mesotrione, atrazine and acetochlor in water were determined by the SPE cartridge coupled with high performance liquid chromatography (HPLC). In the range of 0.5 - 3.0 mg/L, the relationships between the peak areas and mass concentrations of mesotrione, atrazine and acetochlor were linear with the correlation coefficients of 0.9936, 0.9925, 0.9919, respectively. The limits of detection were 5.41, 6.72 and 13.4 microg/L for mesotrione, atrazine and acetochlor, respectively. The results showed that the zirconium dioxide microspheres coated with polymer have diameters in the range of about 6 to 8 microm, the SPE cartridges of which have high adsorption rate for the targets.

  11. Preparation and in-vitro evaluation of sustained-release metoclopramide hydrochloride microspheres.

    Science.gov (United States)

    Khidr, S H; Niazy, E M; el-Sayed, Y M

    1995-01-01

    Sustained-release metoclopramide microspheres were successfully prepared using cellulose propionate polymer at 1:2 drug to polymer ratio employing solvent evaporation technique and using acetone as the polymer solvent. The prepared microspheres at three stirring speeds were characterized with regard to their drug content, particle size distribution, surface topography using SEM and their release profiles at two different pHs at 37 degrees C. The surface of all samples was smooth with very few irregular elevations or depressions. The average particle size decreases as the rotational speed increases and was found to be 1320, 774 and 345 microns at 600, 900 and 1200 rpm, respectively. The average % drug entrapped was found to be 90.5, 100.1 and 60.0% at 600, 900 and 1200 rpm, respectively. Small differences in the release rate were observed due to different rotation speeds with an apparent lower dissolution for batches produced at 1200 rpm probably due to the properties of the coat. The effect of storage under accelerated conditions for 10 weeks on the release characteristics of these microspheres was also studied. The release properties of the microspheres did not change after storing them at 40 degrees C/80% relative humidity for 10 weeks.

  12. Sunitinib microspheres based on [PDLLA-PEG-PDLLA]-b-PLLA multi-block copolymers for ocular drug delivery.

    Science.gov (United States)

    Ramazani, F; Hiemstra, C; Steendam, R; Kazazi-Hyseni, F; Van Nostrum, C F; Storm, G; Kiessling, F; Lammers, T; Hennink, W E; Kok, R J

    2015-09-01

    Sunitinib is a multi-targeted receptor tyrosine kinase (RTK) inhibitor that blocks several angiogenesis related pathways. The aim of this study was to develop sunitinib-loaded polymeric microspheres that can be used as intravitreal formulation for the treatment of ocular diseases. A series of novel multi-block copolymers composed of amorphous blocks of poly-(D,L-lactide) (PDLLA) and polyethylene glycol (PEG) and of semi-crystalline poly-(L-lactide) (PLLA) blocks were synthesized. Sunitinib-loaded microspheres were prepared by a single emulsion method using dichloromethane as volatile solvent and DMSO as co-solvent. SEM images showed that the prepared microspheres (∼ 30 μm) were spherical with a non-porous surface. Sunitinib-loaded microspheres were studied for their degradation and in-vitro release behavior. It was found that increasing the percentage of amorphous soft blocks from 10% to 30% accelerated the degradation of the multi-block copolymers. Sunitinib microspheres released their cargo for a period of at least 210 days by a combination of diffusion and polymer erosion. The initial burst (release in 24h) and release rate could be tailored by controlling the PEG-content of the multi-block copolymers. Sunitinib-loaded microspheres suppressed angiogenesis in a chicken chorioallantoic membrane (CAM) assay. These microspheres therefore hold promise for long-term suppression of ocular neovascularization.

  13. Metal ion-induced alginate-locust bean gum IPN microspheres for sustained oral delivery of aceclofenac.

    Science.gov (United States)

    Jana, Sougata; Gandhi, Arijit; Sheet, Subrata; Sen, Kalyan Kumar

    2015-01-01

    The alginate microspheres represent a useful tool for sustained oral delivery of drugs but exhibit several problems associated with the stability and rapid release of drugs at higher pH values. To overcome these drawbacks, alginate-locust bean gum (LBG) interpenetrating microspheres were prepared by calcium ion (Ca(+2)) induced ionotropic gelation technique for prolonged release of aceclofenac. The drug entrapment efficiency of these microspheres was found to be 59-93%. The microspheres lied in the size range of 406-684μm. Scanning electron microscopy revealed spherical shape of the microspheres. No drug-polymer interaction was evident after infrared spectroscopy analysis. The microspheres provided sustained release of aceclofenac in phosphate buffer solution (pH 6.8) over a period of 8h. The drug release data were fitted into the Korsmeyer-Peppas model and the drug release was found to follow anomalous (non-Fickian) diffusion mechanism. Pharmacodynamic study of the microspheres showed a prolonged anti-inflammatory activity in carrageenan-induced rat paw model following oral administration.

  14. Microsphere Super-resolution Imaging

    CERN Document Server

    Wang, Zengbo

    2015-01-01

    Recently, it was discovered that microsphere can generate super-resolution focusing beyond diffraction limit. This has led to the development of an exciting super-resolution imaging technique -microsphere nanoscopy- that features a record resolution of 50 nm under white lights. Different samples have been directly imaged in high resolution and real time without labelling, including both non-biological (nano devices, structures and materials) and biological (subcellular details, viruses) samples. This chapter reviews the technique, which covers its background, fundamentals, experiments, mechanisms as well as the future outlook.

  15. Facile Preparation of Phosphotungstic Acid-Impregnated Yeast Hybrid Microspheres and Their Photocatalytic Performance for Decolorization of Azo Dye

    Directory of Open Access Journals (Sweden)

    Lan Chen

    2013-01-01

    Full Text Available Phosphotungstic acid (HPW-impregnated yeast hybrid microspheres were prepared by impregnation-adsorption technique through tuning pH of the aqueous yeast suspensions. The obtained products were characterized by field emission scanning electron microscopy (FE-SEM, energy dispersive spectrometry (EDS, X-ray diffraction (XRD, thermogravimetry-differential scanning calorimetry (TG-DSC, and ultraviolet-visible spectrophotometry (UV-Vis, respectively. FE-SEM and EDS ascertain that the HPW has been effectively introduced onto the surface of yeast, and the resulting samples retain ellipsoid shape, with the uniform size (length 4.5 ± 0.2 μm, width 3.0 ± 0.3 μm and good monodispersion. XRD pattern indicates that the main crystal structure of as-synthesized HPW@yeast microsphere is Keggin structure. TG-DTA states that the HPW in composites has better thermal stability than pure HPW. Fourier transform infrared spectroscopy (FT-IR elucidates that the functional groups or chemical bonds inherited from the pristine yeast cell were critical to the assembling of the composites. UV-Vis shows that the obtained samples have a good responding to UV light. The settling ability indicates that the hybrid microspheres possess an excellent suspension performance. In the test of catalytic activity, the HPW@yeast microsphere exhibits a high photocatalytic activity for the decoloration of Methylene blue and Congo red dye aqueous solutions, and there are a few activity losses after four cycles of uses.

  16. Hierarchical flower-like nickel(II) oxide microspheres with high adsorption capacity of Congo red in water.

    Science.gov (United States)

    Zheng, Yingqiu; Zhu, Bicheng; Chen, Hua; You, Wei; Jiang, Chuanjia; Yu, Jiaguo

    2017-10-15

    Monodispersed hierarchical flower-like nickel(II) oxide (NiO) microspheres were fabricated by a facile solvothermal reaction with the assistance of ethanolamine and a subsequent calcination process. The as-synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption isotherms, zeta potential measurement and Fourier transform infrared spectroscopy. Flower-like nickel(II) hydroxide microspheres with uniform diameters of approximate 6.3μm were obtained after the solvothermal reaction. After heat treatment at 350°C, the crystal phase transformed to NiO, but the hierarchical porous structure was maintained. The as-prepared microspheres exhibited outstanding performance for the adsorption of Congo red (CR), an anionic organic dye, from aqueous solution at circumneutral pH. The pseudo-second-order model can make a good description of the adsorption kinetics, while Langmuir model could well express the adsorption isotherms, with calculated maximum CR adsorption capacity of 534.8 and 384.6mgg(-1), respectively, for NiO and Ni(OH)2. The adsorption mechanism of CR onto the as-synthesized samples can be mainly attributed to electrostatic interaction between the positively charged sample surface and the anionic CR molecules. The as-prepared NiO microspheres are a promising adsorbent for CR removal in water treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. PREPARATION AND IN-VITRO EVALUATION OF BACLOFEN LOADED MICROSPHERES

    Directory of Open Access Journals (Sweden)

    Polepalle Madhulatha

    2012-09-01

    Full Text Available The present study was aimed to prepare Baclofen microspheres for sustained release using various polymers such as ethyl cellulose (hydrophobic, hydroxy propyl methyl cellulose (hydrophilic by employing solvent evaporation technique. Drug and excipients compatibility was studied by Fourier Transform Infrared Spectroscopy and no incompatibility was observed. The obtained microspheres were evaluated for the percent drug content, entrapment efficiency and in-vitro dissolution studies. The entrapment efficiency of the obtained formulations was in between 66-88% and in-vitro release of F7 formulation showed 93% in 24 hrs. Scanning Electron Microscopy, Differential Scanning Calorimetry and X-Ray Diffraction studies were performed for F7 formulation. From the results Scanning Electron Microscopy of reveals that microspheres was found in spherical and porous nature. X-Ray Diffraction studies results showed baclofen was in amorphous form which was further confirmed by Differential Scanning Calorimetry. The curve fitting data revealed that the release of obtained formulations follows mixed order kinetics with non‐fickian type of drug release (anomalous.

  18. Biocompatible magnetic microspheres for Use in PDT and hyperthermia.

    Science.gov (United States)

    Vaccari, C B; Cerize, N N P; Morais, P C; Ré, M I; Tedesco, A C

    2012-06-01

    Loaded microspheres with a silicon (IV) phthalocyanine derivative (NzPC) acting as a photosensitizer were prepared from polyhydroxybutyrate-co-valerate (PHBHV) and poly(ecaprolactone) (PCL) polymers using the emulsification solvent evaporation method (EE). The aim of our study was to prepare two systems of these biodegradable PHBHV/PCL microspheres. The first one containing only photosensitizer previously incorporated in the PHBHV and poly(ecaprolactone) (PCL) microspheres and the second one with the post magnetization of the DDS with magnetic nanoparticles. Magnetic fluid is successfully used for controlled incorporation of nanosized magnetic particles within the micron-sized template. This is the first time that we could get a successful pos incorporation of nanosized magnetic particles in a previously-prepared polymeric template. This procedure opens a great number of possibilities of post-functionalization of polymeric micro or nanoparticles with different bioactive materials. The NzPC release profile of the systems is ideal for PDT, the zeta potential and the size particle are stable upon aging in time. In vitro studies were evaluated using gingival fibroblastic cell line. The dark citotoxicity, the phototoxicity and the AC magnetic field assays of the as-prepared nanomagnetic composite were evaluated and the cellular viability analyzed by the classical test of MTT.

  19. pH-sensitive mebeverine microspheres for colon delivery

    Directory of Open Access Journals (Sweden)

    Dandagi P

    2009-01-01

    Full Text Available Mebeverine hydrochloride is known to suffer from extensive first pass effect. In an attempt to improve its oral bioavailability and possibility to restrict its absorption only to the colon, mebeverine microspheres were prepared by emulsion solvent evaporation method. Four formulations were prepared with varying drug and polymer ratio. These formulations were subjected to various evaluation parameters like percent practical yield, entrapment efficiency, particle size, in vitro drug release, in vivo activity. Practical yield of the microspheres was up to 89.59% with encapsulation efficiency up to 79.4%. Scanning electron microscopy confirmed that the microsphere structures were smooth, spherical, and discrete and the particles were of the size range 200 to 300 ΅m. In vitro release of the drug showed biphasic release pattern with non-Fickian diffusion release in 12 h. On the basis of drug content, particle size, in vitro release and in vivo studies, formulation F-3 was found to be optimal. Antiirritable bowel syndrome activity was performed in colorectal distention in rat, which is a model for constipation-induced irritable bowel syndrome. The formulations F-2 and F-3 showed significant effect in fecal output when compared to the control as well as the marketed preparation in the constipation-induced irritable bowel syndrome in rats.

  20. Thermoplastic polyurethanes with TDI-based monodisperse hard segments

    NARCIS (Netherlands)

    De, D.; Araichimani, A.; ten Hoopen, Hermina W.M.; Gaymans, R.J.

    2009-01-01

    Polyurethanes with PTMO soft segments and toluene diisocyanate diamide as urethane segment were studied. The toluene diisocyanate diamide urethane segment was monodisperse in length. The soft segment length was changed by extending PTMO with TDI units to a soft segment length varying from 2 250 to

  1. Highly monodisperse bismuth nanoparticles and their three-dimensional superlattices.

    Science.gov (United States)

    Yarema, Maksym; Kovalenko, Maksym V; Hesser, Günter; Talapin, Dmitri V; Heiss, Wolfgang

    2010-11-01

    A simple and reproducible synthesis of highly monodisperse and ligand-protected bismuth nanoparticles (Bi NPs) is reported. The size of the single-crystalline and spherically shaped NPs is controlled between 11 and 22 nm mainly by the reaction temperature. The high uniformity of the NPs allows their self-assembly into long-range-ordered two- and three-dimensional superstructures.

  2. A general approach for monodisperse colloidal perovskites, Chemistry of Materials

    NARCIS (Netherlands)

    Demirors, A.F.; Imhof, A.

    2009-01-01

    We describe a novel general method for synthesizing monodisperse colloidal perovskite particles at room temperature by postsynthesis addition of metal hydroxides to amorphous titania colloids. In previous work, we used titania particles to synthesize homogenously mixed silica-titania composite parti

  3. Role of solvent/non-solvent ratio on microsphere formation using the solvent removal method.

    Science.gov (United States)

    Godbee, J; Scott, E; Pattamunuch, P; Chen, S; Mathiowitz, E

    2004-03-01

    The importance of good solvent concentration in the non-solvent mixture and the non-solvent viscosity on the ability to form microspheres using solvent removal process was investigated. The higher the viscosity of the polymer solutions, the higher the concentration of good solvent needed in the nonsolvent mixture to produce microspheres. This finding was due to faster precipitation of the polymer phase. Also, the addition of a model drug, fluorescein isothiocyanate conjugated-labelled bovine serum albumin, to the polymer solution (10% poly-L-lactic acid:poly(fumaric-co-sebacic) anhydride in methylene chloride) resulted in an overall lower polymer solution viscosity (15.5 cP with fluorescein isothiocyanate conjugated-labelled bovine serum albumin as compared with 18.25 cP for blank polymer at 25 degrees C). Additionally, the effect of good solvent concentration on non-solvent viscosity was evaluated, and the viscosity decreased as the concentration of good solvent increased. The effect of good solvent concentration on the non-solvent mixture on sphere formation was of great importance. Microspheres would not form when the good polymer solvent (methylene chloride) in the non-solvent phase was too low (below 175 ml for poly-L-lactic acid or 150 ml for poly(D,L-lactidco-glycolid)) or was replaced by another good solvent such as ethyl acetate, even though the same viscosity was achieved. It was shown that the concentration of the good solvent in the non-solvent mixture was more of a controlling factor than the viscosity of the non-solvent mixture in microsphere formation and the findings support the conclusion that diffusion is the main controlling parameter in solvent removal.

  4. Controlled release from recombinant polymers.

    Science.gov (United States)

    Price, Robert; Poursaid, Azadeh; Ghandehari, Hamidreza

    2014-09-28

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

  5. Development of Risperidone PLGA Microspheres

    Directory of Open Access Journals (Sweden)

    Susan D’Souza

    2014-01-01

    Full Text Available The aim of this study was to design and evaluate biodegradable PLGA microspheres for sustained delivery of Risperidone, with an eventual goal of avoiding combination therapy for the treatment of schizophrenia. Two PLGA copolymers (50 : 50 and 75 : 25 were used to prepare four microsphere formulations of Risperidone. The microspheres were characterized by several in vitro techniques. In vivo studies in male Sprague-Dawley rats at 20 and 40 mg/kg doses revealed that all formulations exhibited an initial burst followed by sustained release of the active moiety. Additionally, formulations prepared with 50 : 50 PLGA had a shorter duration of action and lower cumulative AUC levels than the 75 : 25 PLGA microspheres. A simulation of multiple dosing at weekly or 15-day regimen revealed pulsatile behavior for all formulations with steady state being achieved by the second dose. Overall, the clinical use of Formulations A, B, C, or D will eliminate the need for combination oral therapy and reduce time to achieve steady state, with a smaller washout period upon cessation of therapy. Results of this study prove the suitability of using PLGA copolymers of varying composition and molecular weight to develop sustained release formulations that can tailor in vivo behavior and enhance pharmacological effectiveness of the drug.

  6. Optical trapping of coated microspheres

    NARCIS (Netherlands)

    Bormuth, V.; Jannasch, A.; Ander, M.; van Kats, C.M.; van Blaaderen, A.; Howard, J.; Schäffer, E.

    2008-01-01

    In an optical trap, micron-sized dielectric particles are held by a tightly focused laser beam. The optical force on the particle is composed of an attractive gradient force and a destabilizing scattering force. We hypothesized that using anti-reflection-coated microspheres would reduce scattering a

  7. Interaction between dimethyldioctadecylammonium bromide-modified PLGA microspheres and hyaluronic acid

    Science.gov (United States)

    Mulia, Kamarza; Devi, Krisanti, Elsa

    2017-02-01

    In application of intravitreal injection, an extended drug delivery system is desired so that the frequency of injection to treat diabetic retinopathy may be reduced. Poly(lactic-co-glycolic acid) polymer (PLGA) was used to encapsulate a model drug in the form of microspheres. The zeta potential of dimethyldioctadecylammonium bromide (DDAB)-modified PLGA microspheres in water was proportional to the DDAB concentration used in the preparation step, up to +57.8 mV. The scanning electron microscope pictures and the zeta potential data (SEM) confirmed that the surface of the PLGA has been modified by the cationic surfactant and that electrostatic interaction between the positively charged microspheres and the negatively charged vitreous were present.

  8. [Sustained release of the antitumor drug paclitaxel from poly(3-hydroxybutyrate)-based microspheres].

    Science.gov (United States)

    Bonartsev, A P; Iaovlev, S G; Filatova, E V; Soboleva, G M; Makhina, T K; Bonartseva, G A; Shaĭtan, K V; Popov, V O; Kirpichnikov, M P

    2011-01-01

    Development of systems of medicines with sustained action on the basis of biodegradable polymers is a promising trend in modem pharmacology. Polyhydroxyalkanoates (POA) attract increasing attention due to their biodegradability and high biocompatibility, which make them suitable for development of novel drug dosage forms. We obtained microspheres on the basis of poly(3-hydroxybutyrate) (PHB) loaded with the antitumor drug paclitaxel. Morphology, drug release kinetics and effect on tumor cells in vitro of microspheres were studied. The data on the kinetics of drug release, biocompatibility and biological activity of the biopolymer microspheres in vitro showed that the studied system of prolonged drug release had lower toxicity and higher efficiency compared to the traditional dosage forms of paclitaxel.

  9. Drastic difference in porous structure of calcium alginate microspheres prepared with fresh or hydrolyzed sodium alginate.

    Science.gov (United States)

    Akamatsu, Kazuki; Maruyama, Kaho; Chen, Wei; Nakao, Aiko; Nakao, Shin-ichi

    2011-11-15

    Fresh or hydrolyzed sodium alginate was used as a material for preparing calcium alginate microspheres, and a drastic difference in porous structure was observed between them, even though the other materials and the preparation method except for the sodium alginate were exactly the same. When fresh sodium alginate was used, nonporous microspheres were obtained. In contrast, when 82-day-hydrolyzed sodium alginate, whose molecular weight became 7% of the molecular weight of the fresh sodium alginate, was used, porous microspheres with 6.5 times larger BET surface area were obtained. XPS studies indicated that the atomic ratio of Ca, the crosslinker of the alginic acid polymer, was almost the same in both cases. Therefore, the difference in porous structure was not attributed to the amount of crosslinking points, but to the low-molecular-weight compounds formed by hydrolysis, and they would work as pore-generating agents. Copyright © 2011 Elsevier Inc. All rights reserved.

  10. Comparative Investigation on Thermal Insulation of Polyurethane Composites Filled with Silica Aerogel and Hollow Silica Microsphere.

    Science.gov (United States)

    Liu, Chunyuan; Kim, Jin Seuk; Kwon, Younghwan

    2016-02-01

    This paper presents a comparative study on thermal conductivity of PU composites containing open-cell nano-porous silica aerogel and closed-cell hollow silica microsphere, respectively. The thermal conductivity of PU composites is measured at 30 degrees C with transient hot bridge method. The insertion of polymer in pores of silica aerogel creates mixed interfaces, increasing the thermal conductivity of resulting composites. The measured thermal conductivity of PU composites filled with hollow silica microspheres is estimated using theoretical models, and is in good agreement with Felske model. It appears that the thermal conductivity of composites decreases with increasing the volume fraction (phi) when hollow silica microsphere (eta = 0.916) is used.

  11. Chitosan microspheres loaded with holmium-165 produced by spray dryer for liver cancer therapy: preliminary experiments

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, Douglas Massao; Pires, Geovanna; Lira, Raphael A. de; Melo, Vitor H.S.; Nascimento, Nanci; Azevedo, Mariangela de Burgos M. de, E-mail: douglas.miyamoto@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Osso Junior, Joao Alberto [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Radiofarmacia

    2011-07-01

    Chitosan is a biopolymer of 2-deoxy-2-amino-D-glucose that is obtained by deacetylation of chitin. It's biocompatible, biodegradable, non toxic and has antitumor activity. Chitosan has many applications, such as their microparticles that can be used to treat prostate cancer, rheumatoid arthritis, and for liver tumor brachytherapy treatment. Our group is developing different biodegradable polymer-based microspheres loaded with holmium-165 for this purpose. The Chitosan microspheres were produced loaded with holmium (III) chloride, and not loaded with it, by Mini Spray Dryer procedure. The microspheres were evaluated by scanning electron microscopy, energy dispersive spectroscopy (EDS), confocal laser scanning microscopy, thermogravimetric analysis, particle size, and X-ray diffraction. The EDS analysis confirmed the holmium chloride presence into the prepared chitosan microparticles. (author)

  12. Fabrication and evaluation of a sustained-release chitosan-based scaffold embedded with PLGA microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Song, Kedong, E-mail: kedongsong@dlut.edu.cn [Dalian R and D Center for Stem Cell and Tissue Engineering, State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China); Liu, Yingchao [Dalian R and D Center for Stem Cell and Tissue Engineering, State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China); Macedo, Hugo M. [Biological Systems Engineering Laboratory, Department of Chemical Engineering, Department of Chemical Engineering, South Kensington Campus, London SW7 2AZ (United Kingdom); Jiang, Lili; Li, Chao; Mei, Guanyu [Dalian R and D Center for Stem Cell and Tissue Engineering, State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China); Liu, Tianqing, E-mail: liutq@dlut.edu.cn [Dalian R and D Center for Stem Cell and Tissue Engineering, State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China)

    2013-04-01

    Nutrient depletion within three-dimensional (3D) scaffolds is one of the major hurdles in the use of this technology to grow cells for applications in tissue engineering. In order to help in addressing it, we herein propose to use the controlled release of encapsulated nutrients within polymer microspheres into chitosan-based 3D scaffolds, wherein the microspheres are embedded. This method has allowed maintaining a stable concentration of nutrients within the scaffolds over the long term. The polymer microspheres were prepared using multiple emulsions (w/o/w), in which bovine serum albumin (BSA) and poly (lactic-co-glycolic) acid (PLGA) were regarded as the protein pattern and the exoperidium material, respectively. These were then mixed with a chitosan solution in order to form the scaffolds by cryo-desiccation. The release of BSA, entrapped within the embedded microspheres, was monitored with time using a BCA kit. The morphology and structure of the PLGA microspheres containing BSA before and after embedding within the scaffold were observed under a scanning electron microscope (SEM). These had a round shape with diameters in the range of 27–55 μm, whereas the chitosan-based scaffolds had a uniform porous structure with the microspheres uniformly dispersed within their 3D structure and without any morphological change. In addition, the porosity, water absorption and degradation rate at 37 °C in an aqueous environment of 1% chitosan-based scaffolds were (92.99 ± 2.51) %, (89.66 ± 0.66) % and (73.77 ± 3.21) %, respectively. The studies of BSA release from the embedded microspheres have shown a sustained and cumulative tendency with little initial burst, with (20.24 ± 0.83) % of the initial amount released after 168 h (an average rate of 0.12%/h). The protein concentration within the chitosan-based scaffolds after 168 h was found to be (11.44 ± 1.81) × 10{sup −2} mg/mL. This novel chitosan-based scaffold embedded with PLGA microspheres has proven to be a

  13. Template-free synthesis of hierarchical TiO2 hollow microspheres as scattering layer for dye-sensitized solar cells

    Science.gov (United States)

    Rui, Yichuan; Wang, Linlin; Zhao, Jiachang; Wang, Hongzhi; Li, Yaogang; Zhang, Qinghong; Xu, Jingli

    2016-04-01

    Hierarchical TiO2 hollow microspheres were synthesized by a 2-step process consisting of thermal hydrolysis and subsequent solvothermal reaction. Quasi-monodispersed solid TiO2 microspheres aggregated by amorphous particles were firstly obtained by the controlled thermal hydrolysis of titanium sulfate, and then the solid structures transformed to hollow ones and crystallized during the subsequent solvothermal treatment. SEM and TEM images of the samples revealed that the morphological evolution was in perfect accordance with the inside-out Ostwald ripening mechanism. The rich porosity and unique hierarchical hollow structure endow the TiO2 microspheres with a large specific surface area of 108.0 m2 g-1. As an effective anode material for dye-sensitized solar cells, TiO2 hollow microspheres showed good capability of dye adsorption and strong light scattering, leading to a comparable energy conversion efficiency to the commercial 18NR-T transparent titania. Finally, a high efficiency of 7.84% was achieved for the bi-layer DSSC by coating the hollow microspheres on top of the 18NR-T titania as the light scattering layer.

  14. Production of microspheres labeled with holmium-166 for liver cancer therapy: the preliminary experience at IPEN/CNEN-SP

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Renata F.; Azevedo, Mariangela B.M.; Nascimento, Nanci; Sene, Frank F.; Martinelli, Jose R.; Osso Junior, Joao A., E-mail: renatafcosta@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2009-07-01

    Microspheres labeled with therapeutic radionuclides for malignancies of liver are widely used in many countries. The internal radionuclide therapy uses a permanently implanted device, such as Therasphere{sup R} or SIR-Spheres{sup R}, or a biodegradable device that provides structural support for the radionuclide of choice and causes the tumor reduction. Three different types of material supports have been investigated, i.e., biodegradable polymer-based, glass-based and resin-based microspheres. Nowadays there is a project concerning the labeling of these 3 materials with {sup 166}Ho being developed at IPEN-CNEN/SP and coordinated by the Radiopharmacy Directory. {sup 166}Ho(t{sub 1/2}=26.8 h) is a beta minus emitter (E{sub max}=1.84 MeV), with right properties for radiotherapy and can be produced with the low power Brazilian Nuclear Reactor IEA-R1m. The aim of this work is to describe the stage of development of this project. The initial experience used resin-based microspheres, a cation exchange resin labeled with {sup 166}Ho, it showed the essential characteristics for liver therapy. Preliminary results of the preparation of glass-based microspheres labeled with {sup 165}Ho showed that 5% of Ho{sub 2}O{sub 3} was incorporated in an aluminosilicate glass, through the process of spheronization by flame, which produced spherical microspheres with 20-40mum particle size. The preparation of biodegradable material, polymer-based microspheres, is in its initial stage and the objective is to prepare and label with {sup 165}Ho different polymer-based microspheres. These combined efforts have been done to offer a national radiotherapeutic product for the the Brazilian nuclear medicine community at fair value and also to offer a viable possibility of treatment for patients affected by liver malignancies. (author)

  15. Chitosan-genipin microspheres for the controlled release of drugs: clarithromycin, tramadol and heparin.

    Science.gov (United States)

    Harris, Ruth; Lecumberri, Elena; Heras, Angeles

    2010-05-26

    The aim of this study was to first evaluate whether the chitosan hydrochloride-genipin crosslinking reaction is influenced by factors such as time, and polymer/genipin concentration, and second, to develop crosslinked drug loaded microspheres to improve the control over drug release. Once the crosslinking process was characterized as a function of the factors mentioned above, drug loaded hydrochloride chitosan microspheres with different degrees of crosslinking were obtained. Microspheres were characterized in terms of size, morphology, drug content, surface charge and capacity to control in vitro drug release. Clarithromycin, tramadol hydrochloride, and low molecular weight heparin (LMWH) were used as model drugs. The obtained particles were spherical, positively charged, with a diameter of 1-10 microm. X-Ray diffraction showed that there was an interaction of genipin and each drug with chitosan in the microspheres. In relation to the release profiles, a higher degree of crosslinking led to more control of drug release in the case of clarithromycin and tramadol. For these drugs, optimal release profiles were obtained for microspheres crosslinked with 1 mM genipin at 50 °C for 5 h and with 5 mM genipin at 50 °C for 5 h, respectively. In LMWH microspheres, the best release profile corresponded to 0.5 mM genipin, 50 °C, 5 h. In conclusion, genipin showed to be eligible as a chemical-crosslinking agent delaying the outflow of drugs from the microspheres. However, more studies in vitro and in vivo must be carried out to determine adequate crosslinking conditions for different drugs.

  16. Chitosan-Genipin Microspheres for the Controlled Release of Drugs: Clarithromycin, Tramadol and Heparin

    Directory of Open Access Journals (Sweden)

    Ruth Harris

    2010-05-01

    Full Text Available The aim of this study was to first evaluate whether the chitosan hydrochloride-genipin crosslinking reaction is influenced by factors such as time, and polymer/genipin concentration, and second, to develop crosslinked drug loaded microspheres to improve the control over drug release. Once the crosslinking process was characterized as a function of the factors mentioned above, drug loaded hydrochloride chitosan microspheres with different degrees of crosslinking were obtained. Microspheres were characterized in terms of size, morphology, drug content, surface charge and capacity to control in vitro drug release. Clarithromycin, tramadol hydrochloride, and low molecular weight heparin (LMWH were used as model drugs. The obtained particles were spherical, positively charged, with a diameter of 1–10 μm. X-Ray diffraction showed that there was an interaction of genipin and each drug with chitosan in the microspheres. In relation to the release profiles, a higher degree of crosslinking led to more control of drug release in the case of clarithromycin and tramadol. For these drugs, optimal release profiles were obtained for microspheres crosslinked with 1 mM genipin at 50 ºC for 5 h and with 5 mM genipin at 50 ºC for 5 h, respectively. In LMWH microspheres, the best release profile corresponded to 0.5 mM genipin, 50 ºC, 5 h. In conclusion, genipin showed to be eligible as a chemical-crosslinking agent delaying the outflow of drugs from the microspheres. However, more studies in vitro and in vivo must be carried out to determine adequate crosslinking conditions for different drugs.

  17. Encapsulation and characterization of controlled release flurbiprofen loaded microspheres using beeswax as an encapsulating agent.

    Science.gov (United States)

    Ranjha, Nazar M; Khan, Hafeezullah; Naseem, Shahzad

    2010-05-01

    The aim of the present study was to extend the use of flurbiprofen in clinical settings by avoiding its harmful gastric effects. For this purpose, we designed the controlled release solid lipid flurbiprofen microspheres (SLFM) by emulsion congealing technique. Drug was entrapped into gastro resistant biodegradable beeswax microspheres which were prepared at different drug/beeswax ratios 1:1, 1:2 and 1:3 using gelatin and tween 20 as emulsifying agents. The effect of emulsifiers and the effect drug/beeswax ratios were studied on hydration rate, encapsulating efficiency, micromeritic properties, scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (X-RD) analysis and in vitro drug release at pH 1.2 for 2 h and at pH 6.8 for 10 h. SEM revealed that microspheres made with tween 20 were smooth while microspheres made with gelatin showed porous morphology, however, they were all spherical in nature. The practical yield (recovery) showed a dependence on drug-beeswax ratio and it was variable from 53 to 84%. High loading encapsulating efficiency of flurbiprofen from 8 to 94% was achieved. FTIR and DSC analysis confirmed the absence of any drug polymer interaction indicating drug stability during microencapsulation. X-RD of pure flurbiprofen shows sharp peaks, which decreases on encapsulation, indicating decrease in the crystallinity of drug in microspheres. The micromeritic studies confirmed the presence of excellent and good flow properties of microspheres. Entrapment efficiency, morphology, practical yield, hydration rate, flow properties demonstrated their dependence on the HLB value of emulsifiers and emulsifiers with higher HLB were found more appropriate for effective microencapsulation of flurbiprofen. The release kinetics followed zero order mechanism of drug release at pH 6.8. Release pattern depends on the morphology of flurbiprofen microspheres and amount of beeswax used in

  18. 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

  19. Scalable synthesis of mesoporous titania microspheres via spray-drying method.

    Science.gov (United States)

    Pal, Manas; Wan, Li; Zhu, Yongheng; Liu, Yupu; Liu, Yang; Gao, Wenjun; Li, Yuhui; Zheng, Gengfeng; Elzatahry, Ahmed A; Alghamdi, Abdulaziz; Deng, Yonghui; Zhao, Dongyuan

    2016-10-01

    Mesoporous TiO2 has several potential applications due to its unique electronic and optical properties, although its structures and morphologies are typically difficult to tune because of its uncontrollable and fast sol-gel reaction. In this study we have coupled the template-directed-sol-gel-chemistry with the low-cost, scalable, and environmentally benign aerosol (spray-drying) one-pot preparation technique for the fabrication of hierarchically mesoporous TiO2 microspheres and Fe3O4@mesoporous TiO2-x microspheres in a large scale. Parameters during the pre-hydrolysis and spray-drying treatment were varied to successfully control the bead diameter, morphology, monodispersity, surface area and pore size for improving their effectiveness for better application. Unlike to the previous aerosol synthetic approaches, where mainly quite a high temperature gradient with the strict control of spray-drying precursor concentration is implied, our strategy is lying on comparatively low drying temperature with an additional post-ultrasonication (further hydrolysis and condensation) route of the pre-calcined TiO2 samples. As-synthesized mesoporous microspheres have a size distribution from 500nm to 5μm, specific surface areas ranging from 150 to 162m(2)g(-1) and mean pore sizes of several nanometers (4-6nm). Further Fe3O4@mesoporous TiO2-x microspheres were observed to show remarkable selective phosphopeptide-enrichment activity which might have significant importance in disease diagnosis and other biomedical applications.

  20. Design of phosphated cross-linked microspheres of bael fruit gum as a biodegradable carrier.

    Science.gov (United States)

    Mahammed, Nawaz; Gowda, D V; Deshpande, Rohan D; Thirumaleshwar, Shailesh

    2015-01-01

    Present work was aimed at designing of phosphated cross-linked microspheres of bael fruit gum (BFG) by emulsification method using sodium-tri-meta phosphate as a cross-linking agent for treatment of colon cancer using 5-fluorouracil as model drug. Stirring speed was found to be 1,000 rpm for about 5 h to be optimal to obtain reproducible microspheres. It was found that there is an increase in particle size as polymer concentration is increased whereas a reduction in particle size was observed as there is increase in stirring speed. Cross-linked BFG microspheres were successfully prepared by emulsification method. Optimum surfactant concentration was found to be 2 % w/w. Scanning electron microscopy studies showed that the drug-loaded microspheres were non-aggregated and in spherical shape. Differential scanning calorimetry and Fourier transform infrared-spectroscopy studies showed that drug and excipients are compatible. Release studies showed that drug release was more profound in cecal medium induced with enzymes causing degradation of the cross linked BFG than that of the release showed in simulated intestinal fluid. Stability studies showed that there were no significant changes in the drug content and physical appearance of microspheres.

  1. ERYTHROMYCIN POLYLACTIC ACID MICROSPHERES FOR LUNG TARGETING

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    AIM: To prepare polylactic acid microspheres of Erythromycin for Lung targeting.METHEDS: The orthogonal test design was used to optimize the technology,of preparation. Thecharacter of the microspheres, drug release in vitro, stability and tissue distribution were examinedRESULTS: The Erythromycin polylactic acid microspheres was regular in its morphology. Drugwas enveloped in microspheres but not physically mixed with PDLLA. The average particle size was11.65μn with over 94% of the microspheres being in the range of 5~20trn; The drug loading andthe incorporation efciency were 18% and 60% respectively. The microspheres were stable for threemonth at 4 ℃ and room temperature. The in vitro release properties could be expressed by theHiguchi's equation: y = 28.067 + 3.8515t11/2 (r = 0.9834). Comparing with injection, the drug inmicrospheres was more concentrated in lung tissue. CONCLUSION: Erythromycin polylactic acidmicrospheres showed significant sustained release and lung targeting.

  2. Spherical molecularly imprinted polymer particles : A promising tool for molecular recognition in capillary electrokinetic separations

    NARCIS (Netherlands)

    de Boer, T; Mol, R; de Zeeuw, RA; de Jong, GJ; Sherrington, DC; Cormack, PAG; Ensing, K

    2002-01-01

    Spherical molecularly imprinted polymer particles obtained via precipitation polymerization, were introduced as a pseudostationary phase in capillary electrophoresis (CE) to study molecular recognition. Analyses were performed via a partial filling technique using (+)-ephedrine-imprinted microsphere

  3. Magnetoresponsive Photonic Microspheres with Structural Color Gradient.

    Science.gov (United States)

    Lee, Seung Yeol; Choi, Jongkook; Jeong, Jong-Ryul; Shin, Jung H; Kim, Shin-Hyun

    2017-02-06

    Photonic Janus particles are created by alternately sputtering silica and titania on microspheres in order to obtain a structural color gradient. In addition, the microspheres are rendered magnetoresponsive. The Janus microspheres with optical and magnetic anisotropy enable on-demand control over orientation and structural color through manipulation of an external magnetic field, thereby being useful as active color pigments for reflection-mode displays.

  4. Preparation and in vitro characterization of mucoadhesive hydroxypropyl guar microspheres containing amlodipine besylate for nasal administration.

    Science.gov (United States)

    Swamy, N G N; Abbas, Z

    2011-11-01

    Amlodipine besylate microspheres for intranasal administration were prepared with an aim to avoid first-pass metabolism, to achieve controlled blood level profiles and to improve therapeutic efficacy. Hydroxypropyl Guar, a biodegradable polymer, was used in the preparation of microspheres by employing water in oil emulsification solvent evaporation technique. The formulation variables were drug concentration, emulsifier concentration, temperature, agitation speed and polymer concentration. All the formulations were evaluated for particle size, particle shape and surface morphology by scanning electron microscopy, percentage yield, drug entrapment efficiency, in vitro mucoadhesion test, degree of swelling and in vitro drug diffusion through sheep nasal mucosa. The microspheres obtained were free flowing, spherical and the particles ranged in size from 13.4±2.38 μm to 43.4±1.92 μm very much suitable for nasal delivery. Increasing polymer concentration resulted in increased drug entrapment efficiency and increased particle size. Amlodipine besylate was entrapped into the microspheres with an efficiency of 67.2±1.18 % to 81.8±0.64 %. The prepared microspheres showed good mucoadhesion properties, swellability and sustained the release of the drug over a period of 8 h. The data obtained were analysed by fitment into various kinetic models; it was observed that the drug release was matrix diffusion controlled and the release mechanism was found to be non-Fickian. Stability studies were carried out on selected formulations at 5±3°, 25±2°/60±5% RH and 40±2°/75±5% RH for 90 days. The drug content was observed to be within permissible limits and there were no significant deviations in the in vitro mucoadhesion and in vitro drug diffusion characteristics.

  5. Preparation and in vitro characterization of mucoadhesive hydroxypropyl guar microspheres containing amlodipine besylate for nasal administration

    Directory of Open Access Journals (Sweden)

    N. G. N. Swamy

    2011-01-01

    Full Text Available Amlodipine besylate microspheres for intranasal administration were prepared with an aim to avoid first-pass metabolism, to achieve controlled blood level profiles and to improve therapeutic efficacy. Hydroxypropyl Guar, a biodegradable polymer, was used in the preparation of microspheres by employing water in oil emulsification solvent evaporation technique. The formulation variables were drug concentration, emulsifier concentration, temperature, agitation speed and polymer concentration. All the formulations were evaluated for particle size, particle shape and surface morphology by scanning electron microscopy, percentage yield, drug entrapment efficiency, in vitro mucoadhesion test, degree of swelling and in vitro drug diffusion through sheep nasal mucosa. The microspheres obtained were free flowing, spherical and the particles ranged in size from 13.4±2.38 μm to 43.4±1.92 μm very much suitable for nasal delivery. Increasing polymer concentration resulted in increased drug entrapment efficiency and increased particle size. Amlodipine besylate was entrapped into the microspheres with an efficiency of 67.2±1.18 % to 81.8±0.64 %. The prepared microspheres showed good mucoadhesion properties, swellability and sustained the release of the drug over a period of 8 h. The data obtained were analysed by fitment into various kinetic models; it was observed that the drug release was matrix diffusion controlled and the release mechanism was found to be non-Fickian. Stability studies were carried out on selected formulations at 5±3° , 25±2° /60±5% RH and 40±2° /75±5% RH for 90 days. The drug content was observed to be within permissible limits and there were no significant deviations in the in vitro mucoadhesion and in vitro drug diffusion characteristics.

  6. STUDY ON THE FORMATION MECHANISM OF MONODISPERSE PARTICLES IN THE EMULSIFIER-FREE EMULSION POLYMERIZATION OF METHYL METHACRYLATE AND BUTYL ACRYLATE

    Institute of Scientific and Technical Information of China (English)

    Hong-quan Xie; Gui-ying Liao; Yu Gao

    2003-01-01

    The formation mechanism of monodisperse polymer latex particles in the emulsifier-free emulsion polymerization of methyl methacrylate and butyl acrylate with potassium persulfate as initiator was investigated. A multi-step formation mechanism for the monodisperse polymer particles was proposed. The nucleation mechanism is considered to be the coagulation of the precursor particles by homogeneous nucleation when the primary particles reach a critical size with high surface charge density and sufficient stability. It had been proved by a special experiment that the early latex particles formed by the coagulation were stable. The primary particles grow by absorbing monomers and radicals in the polymerization system and then become colloidally unstable again due to the understandable decrease of particle surface charge density, which leads to the aggregation of the growing particles and the formation of larger latex particles therefrom. After the nucleation period,the preferential aggregation of the smaller particles in the propagation process leads to the change of the particles towards a uniform size and narrower particle size distribution. The coexistence and competition of homogeneous nucleation,coagulation, propagation and aggregation result in the increase of the polydispersity index (U = D43/D10) in the first stage,then its decrease in the later stage because of the competition of propagation and aggregation, and the gradual formation of the monodisperse particles.

  7. Microsphere assembly of TiO2 mesoporous nanosheets with highly exposed (101) facets and application in a light-trapping quasi-solid-state dye-sensitized solar cell

    Science.gov (United States)

    Tao, Xiyun; Ruan, Peng; Zhang, Xiang; Sun, Hongxia; Zhou, Xingfu

    2015-02-01

    The morphology of nano-titania has a significant effect on the photoelectric properties of dye-sensitized solar cells. In this study, microsphere assembly of a TiO2 mesoporous nanosheet constructed by nanocuboids was conducted via a simple hydrothermal process. The XRD pattern indicated that the hierarchical mesoporous microspheres are anatase phase with decreased (004) peaks. Raman spectrum shows enhanced Eg peaks at 143 and 638 cm-1 caused by the symmetric stretching vibration of O-Ti-O of the (101) crystalline facet in anatase TiO2. FESEM and TEM images show that well monodispersed TiO2 microspheres with a diameter of 2 μm are assembled by TiO2 mesoporous nanosheets with exposed (101) facets. The oriented attachment of TiO2 nanocuboids along the (101) direction leads to the formation of mesoporous titania nanosheets. The UV-Vis spectrum shows that the mesoporous TiO2 nanosheets have high scattering ability and light absorption by dye. Quasi-solid-state dye-sensitized solar cells that incorporate these microspheres into the top scattering layers exhibit a prominent improvement in the power conversion efficiency of 7.51%, which shows a 45.8% increase in the overall conversion efficiency when compared with the spine hierarchical TiO2 microspheres (5.15%). There is the potential application for microsphere assembly of mesoporous TiO2 nanosheets in quasi-solid-state dye-sensitized solar cells with excellent stability.

  8. Influence of Sodium Alginate on Hypoglycemic Activity of Metformin Hydrochloride in the Microspheres Obtained by the Spray Drying

    National Research Council Canada - National Science Library

    Szekalska, Marta; Wróblewska, Magdalena; Sosnowska, Katarzyna; Winnicka, Katarzyna

    2016-01-01

      Alginate microspheres with metformin hydrochloride were prepared by the spray drying method in order to improve residence time of drug in the stomach. Nine formulations (F1-F9) with various drug : polymer ratio (1 : 2, 1 : 1, and 2 : 1...

  9. Comparative bio-safety and in vivo evaluation of native or modified locust bean gum-PVA IPN microspheres.

    Science.gov (United States)

    Kaity, Santanu; Ghosh, Animesh

    2015-01-01

    Strategically developed natural polymer-based controlled release multiparticulate drug delivery systems have gained special interest for “spatial placement” and “temporal delivery” of drug molecules. In our earlier study, locust bean gum-poly(vinyl alcohol) interpenetrating polymer network (LBG-PVA IPN), carboxymethylated locust bean gum-poly(vinyl alcohol) interpenetrating polymer network (CMLBG-PVA IPN) and acrylamide grafted locust bean gum-poly(vinyl alcohol) interpenetrating polymer network (Am-g-LBG-PVA IPN) were prepared and characterized. The present study deals with accelerating stability testing, comparative bio-safety and single dose in vivo pharmacokinetic study of all three IPN microspheres for controlled oral delivery of buflomedil hydrochloride (BH). From the stability study, it was observed that the particles were stable throughout the study period. From toxicity and biodegradability study it was proved that the microspheres were safe for internal use and complied with bio-safety criterion. From the in vivo pharmacokinetic study in rabbits, it was observed that the CMLBG-PVA IPN microspheres possessed almost similar Tmax value with BH oral suspension. However, in comparison between the LBG-PVA and Am-g-LBG-PVA IPN microspheres, the later showed well controlled release property than the first in biological condition. Thus, this type of delivery system might be useful to achieve the lofty goals of the controlled release drug delivery.

  10. A co-flow-focusing monodisperse microbubble generator

    KAUST Repository

    Zhang, Jiaming

    2014-02-14

    We use a simple and inexpensive microfluidic device, which is based on microscope glass slides and two tapered glass capillaries, to produce monodisperse microbubbles. The innermost capillary used for transporting the gas is inserted into the second capillary, with its 2 μm sharp tip aligned with the center of the converging-diverging throat of the second capillary. This configuration provides a small and smooth gas flow rate, and a high velocity gradient at the tube outlet. Highly monodisperse microbubbles with diameters ranging from 3.5 to 60 microns have been successfully produced at a rate of up to 40 kHz. A simple scaling law, which is based on the capillary number and liquid-to-gas flow rate ratio, successfully predicts the bubble size. © 2014 IOP Publishing Ltd.

  11. Synthesis and antimicrobial activity of monodisperse copper nanoparticles.

    Science.gov (United States)

    Kruk, Tomasz; Szczepanowicz, Krzysztof; Stefańska, Joanna; Socha, Robert P; Warszyński, Piotr

    2015-04-01

    Metallic monodisperse copper nanoparticles at a relatively high concentration (300 ppm CuNPs) have been synthesized by the reduction of copper salt with hydrazine in the aqueous SDS solution. The average particles size and the distribution size were characterized by Dynamic Light Scattering (DLS), Nanosight-Nanoparticle Tracking Analysis (NTA). The morphology and structure of nanoparticles were investigated using Scanning Electron Microscopy (SEM). The chemical composition of the copper nanoparticles was determined by X-ray Photoelectron Spectroscopy (XPS). Monodisperse copper nanoparticles with average diameter 50 nm were received. UV/vis absorption spectra confirmed the formation of the nanoparticles with the characteristic peak 550 nm. The antimicrobial studies showed that the copper nanoparticles had high activity against Gram-positive bacteria, standard and clinical strains, including methicillin-resistant Staphylococcus aureus, comparable to silver nanoparticles and some antibiotics. They also exhibited antifungal activity against Candida species. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Synthesis of Monodisperse Iron Oxide Nanoparticles without Surfactants

    Directory of Open Access Journals (Sweden)

    Xiao-Chen Yang

    2014-01-01

    Full Text Available Monodisperse iron oxide nanoparticles could be successfully synthesized with two kinds of precipitants through a precipitation method. As-prepared nanoparticles in the size around 10 nm with regular spherical-like shape were achieved by adjusting pH values. NaOH and NH3·H2O were used as two precipitants for comparison. The average size of nanoparticles with NH3·H2O precipitant got smaller and represented better dispersibility, while nanoparticles with NaOH precipitant represented better magnetic property. This work provided a simple method without using any organic solvents, organic metal salts, or surfactants which could easily obtain monodisperse nanoparticles with tunable morphology.

  13. Monodispersive CoPt Nanoparticles Synthesized Using Chemical Reduction Method

    Institute of Scientific and Technical Information of China (English)

    SHEN Cheng-Min; HUI Chao; YANG Tian-Zhong; XIAO Cong-Wen; CHEN Shu-Tang; DING Hao; GAO Hong-Jun

    2008-01-01

    @@ Monodispersive CoPt nanoparticles in sizes of about 2.2 nm are synthesized by superhydride reduction of CoCl2 and PtCl2 in diphenyl ether. The as-prepared nanoparticles show a chemically disordered A1 structure and are superparamagnetic. Thermal annealing transforms the A1 structure into chemically ordered L1o structure and the particles are ferromagnetic at room temperature.

  14. Monodisperse magnesium hydride nanoparticles uniformly self-assembled on graphene.

    Science.gov (United States)

    Xia, Guanglin; Tan, Yingbin; Chen, Xiaowei; Sun, Dalin; Guo, Zaiping; Liu, Huakun; Ouyang, Liuzhang; Zhu, Min; Yu, Xuebin

    2015-10-21

    Monodisperse MgH2 nanoparticles with homogeneous distribution and a high loading percent are developed through hydrogenation-induced self-assembly under the structure-directing role of graphene. Graphene acts not only as a structural support, but also as a space barrier to prevent the growth of MgH2 nanoparticles and as a thermally conductive pathway, leading to outstanding performance.

  15. Facile Synthesis of Monodisperse CdS Nanocrystals via Microreaction

    Directory of Open Access Journals (Sweden)

    Zhou Xinggui

    2009-01-01

    Full Text Available Abstract CdS-based nanocrystals (NCs have attracted extensive interest due to their potential application as key luminescent materials for blue and white LEDs. In this research, the continuous synthesis of monodisperse CdS NCs was demonstrated utilizing a capillary microreactor. The enhanced heat and mass transfer in the microreactor was useful to reduce the reaction temperature and residence time to synthesize monodisperse CdS NCs. The superior stability of the microreactor and its continuous operation allowed the investigation of synthesis parameters with high efficiency. Reaction temperature was found to be a key parameter for balancing the reactivity of CdS precursors, while residence time was shown to be an important factor that governs the size and size distribution of the CdS NCs. Furthermore, variation of OA concentration was demonstrated to be a facile tuning mechanism for controlling the size of the CdS NCs. The variation of the volume percentage of OA from 10.5 to 51.2% and the variation of the residence time from 17 to 136 s facilitated the synthesis of monodisperse CdS NCs in the size range of 3.0–5.4 nm, and the NCs produced photoluminescent emissions in the range of 391–463 nm.

  16. Formulation, characterization and in vitro evaluation of floating microspheres of famotidine as a gastro retentive dosage form

    Directory of Open Access Journals (Sweden)

    Jain Abhishek

    2009-01-01

    Full Text Available The present study involves preparation and evaluation of floating microspheres using famotidine (FM as a model drug for prolongation of the gastric retention time. The microspheres were prepared by the solvent evaporation method using different polymers, i.e. acrycoat S100 and cellulose acetate. The size or average diameter (d avg and surface morphology of the prepared microspheres were recognized and characterized by the optical and scanning electron microscopic methods, respectively. In vitro drug release studies were performed and the drug release kinetics were evaluated using the linear regression method. Effects of the stirring rate during preparation, polymer concentration on the size of the microspheres and drug release were also observed. The prepared microspheres exhibited prolonged drug release (18 h and remained buoyant for more than 12 h. The mean particle size increased and the drug release rate decreased at a higher polymer concentration. No significant effect of the stirring rate during preparation on drug release was observed. In vitro studies demonstrated a diffusion-controlled drug release from the microspheres. The objective of the present study was to develop floating microspheres of FM in order to achieve an extended retention in the upper gastrointestinal tract, which may result in enhanced absorption and thereby improved bioavailability. The prepared microspheres were evaluated for particle size, in vitro release and buoyancy and incorporation efficiency. The effect of various formulation variables on the size and drug release was investigated. In vitro drug release studies were performed and the drug release kinetics were evaluated using the linear regression method. FM was obtained as a gift sample from Intas Pharmaceuticals, Ahmedabad, India. Polyvinyl alcohol was obtained from S.D. Fine Chemicals Ltd., Mumbai, India. Dichloromethane, acrycoat S100, cellulose acetate and Tween 80 were obtained from Central Drug House (P

  17. Microspheres in Plasma Display Panels

    Science.gov (United States)

    2006-01-01

    Filling small bubbles of molten glass with gases is just as difficult as it sounds, but the technical staff at NASA is not known to shy away from a difficult task. When Microsphere Systems, Inc. (MSI), of Ypsilanti, Michigan, and Imaging Systems Technology, Inc. (IST), of Toledo, Ohio, were trying to push the limits of plasma displays but were having difficulty with the designs, NASA s Glenn Garrett Morgan Commercialization Initiative (GMCI) assembled key personnel at Glenn Research Center and Ohio State University for a brainstorming session to come up with a solution for the companies. They needed a system that could produce hollow, glass micro-sized spheres (microspheres) that could be filled with a variety of gasses. But the extremely high temperature required to force the micro-sized glass bubbles to form at the tip of a metal nozzle resulted in severe discoloration of the microspheres. After countless experiments on various glass-metal combinations, they had turned to the GMCI for help. NASA experts in advanced metals, ceramics, and glass concluded that a new design approach was necessary. The team determined that what was needed was a phosphate glass composition that would remain transparent, and they went to work on a solution. Six weeks later, using the design tips from the NASA team, Tim Henderson, president of MSI, had designed a new system in which all surfaces in contact with the molten glass would be ceramic instead of metal. Meanwhile, IST was able to complete a Phase I Small Business Innovation Research (SBIR) grant supported by the National Science Foundation (NSF) and supply a potential customer with samples of the microspheres for evaluation as filler materials for high-performance insulations.

  18. Development of molecularly imprinted microspheres for the fast uptake of 4-cumylphenol from water and soil samples.

    Science.gov (United States)

    Narula, Priyanka; Kaur, Varinder; Singh, Raghubir; Kansal, Sushil Kumar

    2014-11-01

    Molecularly imprinted microspheres containing binding sites for the extraction of 4-cumylphenol have been prepared for the first time. The imprinted microspheres were synthesized by a precipitation method using 4-cumylphenol as a template molecule, methacrylic acid as a functional monomer and divinylbenzene-80 as a cross-linker for polymer network formation. The formation and the morphology of molecularly imprinted microspheres were well characterized using infrared spectroscopy, thermogravimetric studies, and scanning electron microscopy. The Brunauer-Emmett-Teller analysis revealed the high surface area of the sorbent indicating formation of molecularly imprinted microspheres. The developed microspheres were employed as a sorbent for the solid-phase extraction of 4-cumylphenol and showed fast uptake kinetics. The sorption parameters were optimized to achieve efficient sorption of the template molecule, like pH, quantity of molecularly imprinted microspheres, time required for equilibrium set-up, sorption kinetics, and adsorption isotherm. A standard method was developed to analyze the sorbed sample quantitatively at 279 nm using high-performance liquid chromatography with diode array detection. It was validated by determining target analyte from synthetic samples, bottled water, spiked tap water, and soil samples. The prepared material is a selective and robust sorbent with good reusability.

  19. Preparation and characterization of nimesulide loaded poly (methyl methacrylate/poly (ethylene oxide blend microspheres: In vitro release studies

    Directory of Open Access Journals (Sweden)

    K Sudhakar

    2013-01-01

    Full Text Available Poly (methyl methacrylate/poly (ethylene oxide (PMMA/PEO blend microspheres were prepared by solvent evaporation technique using poly (vinyl alcohol (PVA as a stabilizer. Nimesulide, an arthritis drug was successfully loaded into these microspheres. The effect of experimental variables such as ratio of ploy (methyl methacrylate to poly (ethylene oxide on nimesulide encapsulation efficiency, release rate, size, and morphology of the microspheres has been investigated. Nimesulide loaded microspheres were analyzed using Fourier transform infrared (FTIR, differential scanning calorimetry (DSC, X-ray diffraction (X-RD, and scanning electron micrograph (SEM. FTIR spectroscopy was used to explain the blending of polymers. DSC and X-RD techniques were used to investigate the crystalline nature of the drug after encapsulation. DSC and X-RD results indicated a nonuniform dispersion of nimesulide in the PMMA/PEO blend matrix. SEMs indicated the formation of spherical microspheres with distinct size. Nimesulide was successfully encapsulated up to 85% in the polymeric matrices. In vitro dissolution experiments performed in pH 7.4 buffer medium indicated a controlled release of nimesulide from blend microspheres up to 12 h.

  20. A facile approach to fabricate Au nanoparticles loaded SiO{sub 2} microspheres for catalytic reduction of 4-nitrophenol

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Mingyi, E-mail: mingyitjucu@163.com [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Huang, Guanbo, E-mail: gbhuang2007@hotmail.com [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Li, Xianxian; Pang, Xiaobo [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Qiu, Haixia [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China)

    2015-07-15

    Hydrophilic and biocompatible macromolecules were used to improve and simplify the process for the fabrication of core/shell SiO{sub 2}@Au composite particles. The influence of polymers on the morphology of SiO{sub 2}@Au particles with different size of SiO{sub 2} cores was analyzed by transmission electron microscopy and scanning electron microscopy. The optical property of the SiO{sub 2}@Au particles was studied with UV–Vis spectroscopy. The results indicate that the structure and composition of macromolecules affect the morphology of Au layers on SiO{sub 2} microspheres. The SiO{sub 2}@Au particles prepared in the presence of polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP) have thin and complete Au nanoshells owing to their inducing act in preferential growth of Au nanoparticles along the surface of SiO{sub 2} microspheres. SiO{sub 2}@Au particles can be also prepared from SiO{sub 2} microspheres modified with 3-aminopropyltrimethoxysilane in the presence of PVA or PVP. This offers a simple way to fabricate a Au layer on SiO{sub 2} or other microspheres. The SiO{sub 2}@Au particles demonstrated high catalytic activity in the reduction of 4-nitrophenol. - Highlights: • Facile direct deposition method for Au nanoparticles on silica microspheres. • Influence of different types of macromolecule on the formation of Au shell. • High catalytic performance of Au nanoparticles on silica microspheres.

  1. Linear and nonlinear viscoelastic properties of bidisperse linear polymers: Mixing law and tube pressure effect

    DEFF Research Database (Denmark)

    van Ruymbeke, E.; Nielsen, J.; Hassager, Ole

    2010-01-01

    In this manuscript, we extend the tube-based model that we developed for predicting the linear viscoelasticity of entangled polymers [van Ruymbeke et al., J. Non-Newtonian Fluid Mech. 128, 7-22 (2005)] to the prediction of the extensional rheology of monodisperse and bidisperse linear polymers...

  2. Holmium-lipiodol-alginate microspheres for fluoroscopy-guided embolotherapy and multimodality imaging.

    Science.gov (United States)

    Oerlemans, Chris; Seevinck, Peter R; Smits, Maarten L; Hennink, Wim E; Bakker, Chris J G; van den Bosch, Maurice A A J; Nijsen, J Frank W

    2015-03-30

    Embolotherapy is a minimally invasive transcatheter technique aiming at reduction or complete obstruction of the blood flow by infusion of micro-sized particles in order to induce tumor regression. A major drawback of the current commercially available and clinically used microspheres is that they cannot be detected in vivo with medical imaging techniques, impeding intra- and post-procedural feedback. It can be expected that real-time monitoring of microsphere infusion and post-procedural imaging will result in better predictability and higher efficacy of the treatment. In this study, a novel microsphere formulation has been developed that can be visualized with fluoroscopy, X-ray computed tomography (CT) and magnetic resonance imaging (MRI). The microspheres were prepared with the JetCutter technique and consist of alginate (matrix-forming polymer), holmium (cross-linking and MRI contrast agent), lipiodol (radiopaque contrast agent) and Pluronic F-68 (surfactant). The mean size (±SEM) of the hydrated holmium-lipiodol-alginate microspheres (Ho-lip-ams) was 570±12 μm with a holmium content of 0.38±0.01% (w/w). Stability studies showed that the microspheres remained intact during incubation for two weeks in fetal calf serum (FCS) at 37 °C. The inclusion of lipiodol in the microspheres rendered excellent visualization capabilities for fluoroscopy and CT, whereas the holmium ions, which keep the alginate network together, also allow MR imaging. In this study it was shown that single sphere detection was possible by fluoroscopy, CT and MRI. The Ho-lip-ams were visualized in real-time, during infusion in a porcine kidney using fluoroscopy, and post-procedural, the deposition of the microspheres was examined with fluoroscopy, (cone beam rotational) CT and MRI. The different imaging modalities showed similar deposition patterns of the microspheres within the organ. The combination of intra-procedural visualization, multimodality imaging for patient follow-up and the

  3. Glass microspheres for medical applications

    Science.gov (United States)

    Conzone, Samuel David

    Radioactive dysprosium lithium borate glass microspheres have been developed as biodegradable radiation delivery vehicles for the radiation synovectomy treatment of rheumatoid arthritis. Once injected into a diseased joint, the microspheres deliver a potent dose of radiation to the diseased tissue, while a non-uniform chemical reaction converts the glass into an amorphous, porous, hydrated dysprosium phosphate reaction product. The non-radioactive, lithium-borate component is dissolved from the glass (up to 94% weight loss), while the radioactive 165Dy reacts with phosphate anions in the body fluids, and becomes "chemically" trapped in a solid, dysprosium phosphate reaction product that has the same size as the un-reacted glass microsphere. Ethylene diamine tetraacetate (EDTA) chelation therapy can be used to dissolve the dysprosium phosphate reaction product after the radiation delivery has subsided. The dysprosium phosphate reaction product, which formed in vivo in the joint of a Sprague-Dawley rat, was dissolved by EDTA chelation therapy in 100 Gy) of localized beta radiation to a treatment site within the body, followed by complete biodegradability. The non-uniform reaction process is a desirable characteristic for a biodegradable radiation delivery vehicle, but it is also a novel material synthesis technique that can convert a glass to a highly porous materials with widely varying chemical composition by simple, low-temperature, glass/solution reaction. The reaction product formed by nonuniform reaction occupies the same volume as the un-reacted glass, and after drying for 1 h at 300°C, has a specific surface area of ≈200 m2/g, a pore size of ≈30 nm, and a nominal crushing strength of ≈10 MPa. Finally, rhenium glass microspheres, composed of micron-sized, metallic rhenium particles dispersed within a magnesium alumino borate glass matrix were produced by sintering ReO2 powder and glass frit at 1050°C. A 50 mg injection of radioactive rhenium glass

  4. Synthesis and characterization of poly(lactic acid-co-glycolic acid) complex microspheres as drug carriers.

    Science.gov (United States)

    Wang, Fang; Liu, Xiuxiu; Yuan, Jian; Yang, Siqian; Li, Yueqin; Gao, Qinwei

    2016-10-01

    Poly(lactic-co-glycolic) acid (PLGA) is synthesized via melt polycondensation directly from lactic acid and glycolic acid with a feed molar ratio of 75/25. Bovine serum albumin, which is used as model protein, is entrapped into the poly(lactic-co-glycolic acid) microspheres with particle size of 260.9 ± 20.0 nm by the double emulsification method. Then it is the first report of producing more carboxyl groups by poly(lactic-co-glycolic acid) surface hydrolysis. The purpose is developing poly(lactic-co-glycolic acid) microspheres surface, which is modified with chitosan by chemical reaction between carboxyl groups and amine groups. The particle size and the positive zeta potential of the poly(lactic-co-glycolic acid)/chitosan microspheres are 388.2 ± 35.6 nm and 10.4 ± 2.9 mV, respectively. The drug loading ratio and encapsulation efficacy of poly(lactic-co-glycolic acid)/chitosan microspheres are 36.3% and 57.5%, which are higher than PLGA microspheres. Furthermore, the drug burst release of poly(lactic-co-glycolic acid)/chitosan microspheres at 10 h is decreased to 21.72% while the corresponding value of the poly(lactic-co-glycolic acid) microsphere is 64.56%. These results reveal that surface hydrolysis modification of poly(lactic-co-glycolic acid) is an efficient method to improve the negative potential and chemical reaction properties of the polymer. And furthermore, this study shows that chitosan-modified poly(lactic-co-glycolic acid) microspheres is a promising system for the controlled release of pharmaceutical proteins.

  5. POROUS WALL, HOLLOW GLASS MICROSPHERES

    Energy Technology Data Exchange (ETDEWEB)

    Sexton, W.

    2012-06-30

    Hollow Glass Microspheres (HGM) is not a new technology. All one has to do is go to the internet and Google{trademark} HGM. Anyone can buy HGM and they have a wide variety of uses. HGM are usually between 1 to 100 microns in diameter, although their size can range from 100 nanometers to 5 millimeters in diameter. HGM are used as lightweight filler in composite materials such as syntactic foam and lightweight concrete. In 1968 a patent was issued to W. Beck of the 3M{trademark} Company for 'Glass Bubbles Prepared by Reheating Solid Glass Particles'. In 1983 P. Howell was issued a patent for 'Glass Bubbles of Increased Collapse Strength' and in 1988 H. Marshall was issued a patent for 'Glass Microbubbles'. Now Google{trademark}, Porous Wall, Hollow Glass Microspheres (PW-HGMs), the key words here are Porous Wall. Almost every article has its beginning with the research done at the Savannah River National Laboratory (SRNL). The Savannah River Site (SRS) where SRNL is located has a long and successful history of working with hydrogen and its isotopes for national security, energy, waste management and environmental remediation applications. This includes more than 30 years of experience developing, processing, and implementing special ceramics, including glasses for a variety of Department of Energy (DOE) missions. In the case of glasses, SRS and SRNL have been involved in both the science and engineering of vitreous or glass based systems. As a part of this glass experience and expertise, SRNL has developed a number of niches in the glass arena, one of which is the development of porous glass systems for a variety of applications. These porous glass systems include sol gel glasses, which include both xerogels and aerogels, as well as phase separated glass compositions, that can be subsequently treated to produce another unique type of porosity within the glass forms. The porous glasses can increase the surface area compared to &apos

  6. Porous microspheres as promising vehicles for the topical delivery of poorly soluble asiaticoside accelerate wound healing and inhibit scar formation in vitro &in vivo.

    Science.gov (United States)

    Zhang, Chen-Zhen; Niu, Jie; Chong, Yee-Song; Huang, Yan-Fen; Chu, Yang; Xie, Sheng-Yang; Jiang, Zhi-Hong; Peng, Li-Hua

    2016-12-01

    Asiaticoside is a natural compound possessing diverse pharmacological effects with great potential for clinical use. However, the low solubility and oil-water partition coefficient of asiaticoside lead to reduced effect and limited application. This study aims to construct a porous microsphere for the sustained release of asiaticoside to improve its absorption and enhance the therapeutic effects. Parameters of the formulations, including the drug to polymer ratio, solvent amounts of the inner and external phases, the stirring speed for preparation, and the drug entrapment efficiency were investigated and optimized. Particle size, morphology, pores structure, and Fourier transform infrared spectrum of the microsphere were characterized. The release kinetics and cellular uptake profiles of the asiaticoside-microspheres were examined. The therapeutic effects of asiaticoside-microspheres on wound healing and skin appendages regeneration were investigated in vitro & in vivo. Results showed that the optimized asiaticoside-microspheres possess spherical spongy structure with cylindrical holes. Asiaticoside can be loaded in the microsphere with high efficiency and released with sustained manner. The cellular uptake of asiaticoside from the microspheres was increased with 9.1 folds higher than that of free solution. Asiaticoside-microspheres expressed the strong promotion in the proliferation, migration of keratinocytes and wound scratching healing in vitro. More importantly, they significantly accelerated the re-epithelization, collagen synthesis and pro-angiogenesis in the rat full-skin wound healing. Porous microsphere was shown a novel carrier for the sustained delivery of poorly soluble asiaticoside, with absorption and therapeutic effects improved. Asiaticoside-microsphere is a promising topical preparation with excellent regenerative effects for the wound therapy.

  7. ERYTHROMYCIN POLYLACTIC ACID MICROSPHERES FOR LUNG TARGETING

    Institute of Scientific and Technical Information of China (English)

    YANGFan; YANBing; 等

    2002-01-01

    AIM:To prepare polylactiv acid microspheres of Erythromycin for Lung targeting.METHEDS:The orthogonal test design was used to optimize the technology of preparation.The character of the microspheres,drug release in vitro,stabiligy and tissue distribution were examined. RESULTS:The Erythromycin polylatic acid microspheres was regular in its morphology.Drug was enveloped in microspheres but not physically mixed with PDLLA.The average particle size was 11.65μm with over 94% of the microspheres being in the range of 5-20μm;The drug loading and the incorporation efficiency were 18% and 60% respectively.The microspheres were stable for three month at 4℃ and room temperature.The in vitro release properties could be expressed by the Higuchi′s equation:y=28.067+3.8515t1/2(r=0.9834).Comparing with injection,the drug in microspheres was more concentrated in lung tissue.CONLUSION:Erythromycin polylactic acid microspheres showed significant sustained release and lung targeting.

  8. Assembly of ordered magnetic microsphere arrays

    Science.gov (United States)

    Xu, Wanling; Ketterson, John

    2008-08-01

    We have developed a straightforward technique to assemble ordered arrays of magnetic microspheres on patterned thin Permalloy (Py) films deposited on the surface of a silicon wafer. Droplets containing micrometer-sized carboxyl paramagnetic microspheres are placed on a horizontally oriented wafer. The field produced by a permanent magnet placed under the wafer is rendered inhomogeneous by the patterned Py features and the resulting field gradients attract and hold the paramagnetic microspheres to these features. While the magnetic microspheres are being attracted to and secured on the pattered Permalloy features, a horizontal flow is created by a pipette, which also removes loose (unsecured) microspheres. By applying this technique to a cocktail of individually functionalized microspheres, a sensor could be realized, which will screen, in parallel, for a large number of targets per unit area. The ability to resolve individual microspheres is close to 100%. A desirable feature is that the substrate is reusable; removing the magnet allows an existing batch of microspheres, which may have lost sensitivity due to environmental exposure, to be flushed from the substrate and replaced with a new batch. The technique complements existing approaches in the field of microarrays widely used in immunoassay, DNA fragment detection, pathogen detection, and other applications in functional genomics and diagnostics.

  9. Microencapsulation and microspheres for food applications

    NARCIS (Netherlands)

    Sagis, L.M.C.

    2015-01-01

    This book provides an update on the latest developments, challenges, and opportunities in the highly expanding field of microencapsulation and microspheres for food applications, examining the various types of microspheres and microcapsules essential to those who need to develop stable and impermeab

  10. Surface-assembled poly(I:C) on PEGylated PLGA microspheres as vaccine adjuvant: APC activation and bystander cell stimulation.

    Science.gov (United States)

    Hafner, Annina M; Corthésy, Blaise; Textor, Marcus; Merkle, Hans P

    2016-11-30

    Biodegradable poly(lactic-co-glycolic acid) (PLGA) microspheres are potential vehicles to deliver antigens for vaccination. Because they lack the full capacity to activate professional antigen presenting cells (APCs), combination with an immunostimulatory adjuvant may be considered. A candidate is the synthetic TLR3 ligand polyriboinosinic acid-polyribocytidylic acid, poly(I:C), which drives cell-mediated immunity. However, poly(I:C) has also been linked to the pathogenesis of autoimmunity, as affected by widespread stimulation of non-hematopoietic bystander cells. To address this aspect, we propose to minimize the poly(I:C) dose as well as to control the stimulation of non-immune bystander cells by poly(I:C). To facilitate the maturation of APCs with minimal poly(I:C) doses, we surface-assembled poly(I:C) onto PLGA microspheres. The microspheres' surface was further modified by poly(ethylene glycol) (PEG) coronas with varying PEG-densities. PLGA microspheres loaded with tetanus toxoid (tt) as model antigen were manufactured by microextrusion-based solvent extraction. The negatively charged PLGA(tt) microspheres were coated with polycationic poly(l-lysine) (PLL) polymers, either PLL itself or PEG-grafted PLL (PLL-g-PEG) with varying grafting ratios (g=2.2 and g=10.1). Stable surface assembly of poly(I:C) was achieved by subsequent incubation of polymer-coated PLGA microspheres with aqueous poly(I:C) solutions. We evaluated the immunostimulatory potential of such PLGA(tt) microsphere formulations on monocyte-derived dendritic cells (MoDCs) as well as human foreskin fibroblasts (HFFs) as model for non-hematopoietic bystander cells. Formulations with surface-assembled poly(I:C) readily activated MoDCs with respect to the expression of maturation-related surface markers, proinflammatory cytokine secretion and directed migration. When surface-assembled, poly(I:C) enhanced its immunostimulatory activity by more than one order of magnitude as compared to free poly

  11. Dextran-based microspheres as controlled delivery systems for proteins

    NARCIS (Netherlands)

    Vlugt-Wensink, K.D.F.

    2007-01-01

    Dextran-based microspheres as controlled delivery systems for proteins Dextran based microspheres are investigated as controlled delivery system for proteins. Microspheres were prepared by polymerization of dex-HEMA in an aqueous two-phase system of dex-HEMA and PEG. Protein loaded microspheres are

  12. All Polymer Micropump

    DEFF Research Database (Denmark)

    Hansen, Thomas Steen

    2008-01-01

    of the substrate, the PEDOT is integrated into the non-conductive polymer. The result is a material that retains the good conductivity of PEDOT, but gains the mechanical stability of the substrate. The best results were obtained for PEDOTjPMMA. The new mechanically stable PEDOTjPMMA was micro-patterned using clean...... (ACEO) micropump. The ACEO pump consists of an array of interdigitated small and large PEDOTjPMMA encapsulated in a polyurethane (PUR) channel system. The pumping velocity was detected using fluorescent microspheres and a confocal microscope. The pump characteristics resembled those of pumps based...

  13. Spectrally resolved resonant propulsion of dielectric microspheres

    CERN Document Server

    Li, Yangcheng; Limberopoulos, Nicholaos I; Urbas, Augustine M; Astratov, Vasily N

    2015-01-01

    Use of resonant light forces opens up a unique approach to high-volume sorting of microspherical resonators with much higher uniformity of resonances compared to that in coupled-cavity structures obtained by the best semiconductor technologies. In this work, the spectral response of the propulsion forces exerted on polystyrene microspheres near tapered microfibers is directly observed. The measurements are based on the control of the detuning between the tunable laser and internal resonances in each sphere with accuracy higher than the width of the resonances. The measured spectral shape of the propulsion forces correlates well with the whispering-gallery mode resonances in the microspheres. The existence of a stable radial trap for the microspheres propelled along the taper is demonstrated. The giant force peaks observed for 20-{\\mu}m spheres are found to be in a good agreement with a model calculation demonstrating an efficient use of the light momentum for propelling the microspheres.

  14. Hydroxyapatite nanocrystal coating on biodegradable microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Okada, Masahiro [Department of Bioengineering, Advanced Medical Engineering Center, National Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565-8565 (Japan); Furuzono, Tsutomu, E-mail: furuzono@ri.ncvc.go.jp [Department of Bioengineering, Advanced Medical Engineering Center, National Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565-8565 (Japan)

    2010-10-15

    Nano-sized single crystals of calcined hydroxyapatite (HAp) were uniformly coated on poly(L-lactic acid) (PLLA) microspheres through the ionic interaction between calcium ions on the HAp nanocrystal and carboxyl groups on the PLLA microsphere. In order to coat the substrate with HAp nanocrystals through ionic interaction, the surfaces of the PLLA microspheres were hydrolyzed in an alkaline aqueous solution at pH 11.0 for 1 h at room temperature. The interaction between the HAp nanocrystals and the carboxyl groups originating from PLLA end groups was estimated by Fourier transform infrared spectroscopy. The alkali-treated PLLA microspheres were coated with HAp nanocrystals by immersing the microspheres in an ethanol dispersion of HAp nanocrystals followed by washing in an ultrasonic bath.

  15. Highly regenerable mussel-inspired Fe₃O₄@polydopamine-Ag core-shell microspheres as catalyst and adsorbent for methylene blue removal.

    Science.gov (United States)

    Xie, Yijun; Yan, Bin; Xu, Haolan; Chen, Jian; Liu, Qingxia; Deng, Yonghong; Zeng, Hongbo

    2014-06-11

    We report a facile method to synthesize Fe3O4@polydopamine (PDA)-Ag core-shell microspheres. Ag nanoparticles (NPs) are deposited on PDA surfaces via in situ reduction by mussel-inspired PDA layers. High catalytic activity and fast adsorption of a model dye methylene blue (MB) at different pH values are achieved mainly due to the presence of monodisperse Ag NPs and electrostatic interactions between PDA and MB. The as-prepared Fe3O4@PDA-Ag microspheres also show high cyclic stability (>27 cycles), good acid stability, and fast regeneration ability, which can be achieved efficiently within several minutes by using NaBH4 as the desorption agent, showing great potentials in a wide range of applications.

  16. Preparation of core-shell Fe{sub 3}O{sub 4}/SiO{sub 2} microspheres as adsorbents for purification of DNA

    Energy Technology Data Exchange (ETDEWEB)

    Gai Ligang; Li Zhili; Jiang Haihui; Han Xiaoyun; Ma Wanyong [Shandong Provincial Key Laboratory of Fine Chemicals, School of Chemical Engineering, Shandong Institute of Light Industry, Jinan 250353 (China); Hou Yunhua, E-mail: liganggai@yahoo.co [Shandong Provincial Key Laboratory of Microbial Engineering, School of Food Science and Bioengineering, Shandong Institute of Light Industry, Jinan 250353 (China)

    2010-11-10

    Nearly monodisperse core-shell Fe{sub 3}O{sub 4}/SiO{sub 2} microspheres have been prepared via a glycol reduction method followed by a modified Stoeber process. The thickness of the silica shells can be tuned in the range 33-53 nm by varying the amount of tetraethyl silicate (TEOS) during syntheses. The magnetic composite microspheres were characterized with XRD, XPS, FTIR, TEM, ICP-OES and VSM, and further tested as adsorbents for purification of plasmid DNA from Escherichia coli DH5{alpha} cells. The magnetic purification of plasmid DNA leads to satisfying integrity, yield and purity in comparison with those isolated by the traditional phenol-chloroform extraction.

  17. Comparison of drug release from poly(lactide-co-glycolide) microspheres and novel fibre formulations.

    Science.gov (United States)

    Campbell, Christopher S J; Delgado-Charro, M Begoña; Camus, Olivier; Perera, Semali

    2016-03-01

    Intraperitoneal cisplatin delivery has recently been shown to benefit ovarian cancer patients. Cisplatin-containing poly(lactide-co-glycolide) (PLGA) microspheres have been proposed for cisplatin delivery. The drug loading of cisplatin containing microspheres produced elsewhere is 3-10%w. Similar microspheres are reported here with a mean diameter of 38.8 µm, and a drug loading of 11.7%w, but using ethyl acetate as a safer solvent. In addition, novel formulations of cisplatin-containing solid and hollow PLGA 65:35 (lactide:glycolide) fibres were prepared and are reported here for the first time. PLGA hollow fibres were produced by phase inversion with a high drug loading of 27%w. Mechanistic mathematical models were applied to the cisplatin release profiles to allow quantitative comparison of microsphere, solid fibre and hollow fibre formulations. The diffusion coefficient of cisplatin eluting from a typical batch of PLGA microspheres was 4.8 × 10(-13) cm(2) s(-1); this low diffusivity of cisplatin in microspheres was caused by the low porosity of the polymer matrix. The diffusion coefficients of cisplatin eluting from a batch of PLGA solid fibres and hollow fibres were 6.1 × 10(-10) and 3.3 × 10(-10) cm(2) s(-1), respectively. These fibres allowed the controlled release of high doses of cisplatin over four days and may represent an improvement in slow release technology for treatment of ovarian cancer.

  18. Binding characteristics of homogeneous molecularly imprinted polymers for acyclovir using an (acceptor-donor-donor)-(donor-acceptor-acceptor) hydrogen-bond strategy, and analytical applications for serum samples.

    Science.gov (United States)

    Wu, Suqin; Tan, Lei; Wang, Ganquan; Peng, Guiming; Kang, Chengcheng; Tang, Youwen

    2013-04-12

    This paper demonstrates a novel approach to assembling homogeneous molecularly imprinted polymers (MIPs) based on mimicking multiple hydrogen bonds between nucleotide bases by preparing acyclovir (ACV) as a template and using coatings grafted on silica supports. (1)H NMR studies confirmed the AAD-DDA (A for acceptor, D for donor) hydrogen-bond array between template and functional monomer, while the resultant monodisperse molecularly imprinted microspheres (MIMs) were evaluated using a binding experiment, high performance liquid chromatography (HPLC), and solid phase extraction. The Langmuir isothermal model and the Langmuir-Freundlich isothermal model suggest that ACV-MIMs have more homogeneous binding sites than MIPs prepared through normal imprinting. In contrast to previous MIP-HPLC columns, there were no apparent tailings for the ACV peaks, and ACV-MIMs had excellent specific binding properties with a Ka peak of 3.44 × 10(5)M(-1). A complete baseline separation is obtained for ACV and structurally similar compounds. This work also successfully used MIMs as a specific sorbent for capturing ACV from serum samples. The detection limit and mean recovery of ACV was 1.8 ng/mL(-1) and 95.6%, respectively, for molecularly imprinted solid phase extraction coupled with HPLC. To our knowledge, this was the first example of MIPs using AAD-DDA hydrogen bonds.

  19. Biofunctionalization of silica microspheres for protein separation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Binjie [Institute of Immunology, Henan University, Kaifeng 475004 (China); Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Kaifeng 475004 (China); Zou, Xueyan [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Kaifeng 475004 (China); Zhao, Yanbao, E-mail: yanbaozhao@126.com [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Kaifeng 475004 (China); Sun, Lei [Institute of Immunology, Henan University, Kaifeng 475004 (China); Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Kaifeng 475004 (China); Li, Shulian [Institute of Immunology, Henan University, Kaifeng 475004 (China)

    2013-07-01

    Mercapto-silica (SiO{sub 2}–SH) microspheres were prepared via direct hydrolysis of 3-mercaptopropyltrimethoxysilane (MPS) in a basic aqueous solution. The content of surface thiol group (-SH) of SiO{sub 2}–SH microspheres was measured by Ellman's reagent method and X-ray photoelectron spectroscopy (XPS) and the content of surface thiol group of SiO{sub 2}–SH microspheres is strongly dependent on the reaction conditions. The thermal stability of SiO{sub 2}–SH microspheres was evaluated by thermogravimetric (TG) analysis, which tended to reduce with the increase of content of surface thiol groups. SiO{sub 2}–SH microspheres can be easily modified with reduced glutathione (GSH) to generate SiO{sub 2}–GSH microspheres for the affinity separation of Glutathione S-transferase (GST). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed to examine the validity of the separation procedure. The results showed that SiO{sub 2}–GSH microspheres were efficient in GST affinity separation from mixed proteins. - Graphical abstract: The prepared SiO{sub 2}–SH microsphere binding reduced glutathione (SiO{sub 2}–GSH) as affinity precipitation support can capture selectively Glutathione S-transferase (GST) from mixed protein solution. Highlights: ► SiO{sub 2}–SH microspheres were prepared in water using one-pot synthesis. ► The content of surface -SH was investigated by Ellman method and XPS spectra. ► The ratio of -SH to mass strongly depends on the reaction conditions. ► SiO{sub 2}–SH microspheres were biofunctionalized by glutathione. ► SiO{sub 2}–GSH can be used to capture selectively Glutathione S-transferase.

  20. Morphologically and size uniform monodisperse particles and their shape-directed self-assembly

    Science.gov (United States)

    Collins, Joshua E.; Bell, Howard Y.; Ye, Xingchen; Murray, Christopher Bruce

    2015-11-17

    Monodisperse particles having: a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology are disclosed. Due to their uniform size and shape, the monodisperse particles self assemble into superlattices. The particles may be luminescent particles such as down-converting phosphor particles and up-converting phosphors. The monodisperse particles of the invention have a rare earth-containing lattice which in one embodiment may be an yttrium-containing lattice or in another may be a lanthanide-containing lattice. The monodisperse particles may have different optical properties based on their composition, their size, and/or their morphology (or shape). Also disclosed is a combination of at least two types of monodisperse particles, where each type is a plurality of monodisperse particles having a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology; and where the types of monodisperse particles differ from one another by composition, by size, or by morphology. In a preferred embodiment, the types of monodisperse particles have the same composition but different morphologies. Methods of making and methods of using the monodisperse particles are disclosed.

  1. Morphologically and size uniform monodisperse particles and their shape-directed self-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Joshua E.; Bell, Howard Y.; Ye, Xingchen; Murray, Christopher Bruce

    2017-09-12

    Monodisperse particles having: a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology are disclosed. Due to their uniform size and shape, the monodisperse particles self assemble into superlattices. The particles may be luminescent particles such as down-converting phosphor particles and up-converting phosphors. The monodisperse particles of the invention have a rare earth-containing lattice which in one embodiment may be an yttrium-containing lattice or in another may be a lanthanide-containing lattice. The monodisperse particles may have different optical properties based on their composition, their size, and/or their morphology (or shape). Also disclosed is a combination of at least two types of monodisperse particles, where each type is a plurality of monodisperse particles having a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology; and where the types of monodisperse particles differ from one another by composition, by size, or by morphology. In a preferred embodiment, the types of monodisperse particles have the same composition but different morphologies. Methods of making and methods of using the monodisperse particles are disclosed.

  2. Fabrication of polystyrene hollow microspheres as laser fusion targets by optimized density-matched emulsion technique and characterization

    Indian Academy of Sciences (India)

    K K Mishra; R K Khardekar; Rashmi Singh; H C Pant

    2002-07-01

    Inertial confinement fusion, frequently referred to as ICF, inertial fusion, or laser fusion, is a means of producing energy by imploding small hollow microspheres containing thermonuclear fusion fuel. Polymer microspheres, which are used as fuel containers, can be produced by solution-based micro-encapsulation technique better known as density-matched emulsion technique. The specifications of these microspheres are very rigorous, and various aspects of the emulsion hydrodynamics associated with their production are important in controlling the final product. This paper describes about the optimization of various parameters associated with density-matched emulsion method in order to improve the surface smoothness, wall thickness uniformity and sphericity of hollow polymer microspheres. These polymer microshells have been successfully fabricated in our lab, with 3–30 m wall thickness and 50–1600 m diameters. The sphericity and wall thickness uniformity are better than 99%. Elimination of vacuoles and high yield rate has been achieved by adopting the step-wise heating of W1/O/W2 emulsion for solvent removal.

  3. Optimization of preparation method for ketoprofen-loaded microspheres consisting polymeric blends using simplex lattice mixture design.

    Science.gov (United States)

    Das, Sanjoy Kumar; Khanam, Jasmina; Nanda, Arunabha

    2016-12-01

    In the present investigation, simplex lattice mixture design was applied for formulation development and optimization of a controlled release dosage form of ketoprofen microspheres consisting polymers like ethylcellulose and Eudragit(®)RL 100; when those were formed by oil-in-oil emulsion solvent evaporation method. The investigation was carried out to observe the effects of polymer amount, stirring speed and emulsifier concentration (% w/w) on percentage yield, average particle size, drug entrapment efficiency and in vitro drug release in 8h from the microspheres. Analysis of variance (ANOVA) was used to estimate the significance of the models. Based on the desirability function approach numerical optimization was carried out. Optimized formulation (KTF-O) showed close match between actual and predicted responses with desirability factor 0.811. No adverse reaction between drug and polymers were observed on the basis of Fourier transform infrared (FTIR) spectroscopy and Differential scanning calorimetric (DSC) analysis. Scanning electron microscopy (SEM) was carried out to show discreteness of microspheres (149.2±1.25μm) and their surface conditions during pre and post dissolution operations. The drug release pattern from KTF-O was best explained by Korsmeyer-Peppas and Higuchi models. The batch of optimized microspheres were found with maximum entrapment (~90%), minimum loss (~10%) and prolonged drug release for 8h (91.25%) which may be considered as favourable criteria of controlled release dosage form.

  4. Real-Time Polymerase Chain Reaction as a Tool for Evaluation of Magnetic Poly(Glycidyl methacrylate)-Based Microspheres in Molecular Diagnostics.

    Science.gov (United States)

    Trachtová, Stepánka; Spanová, Alena; Horák, Daniel; Kozáková, Hana; Rittich, Bohuslav

    2016-01-01

    DNA amplification by real-time polymerase chain reaction (RT-PCR) was used for the evaluation of efficiency of polymer coating of magnetic hydrophilic poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate) (P(HEMA-co-GMA)) and poly(glycidyl methacrylate) (PGMA) microspheres with/without carboxyl groups. The inhibition effect of magnetic microspheres on real-time polymerase chain reaction (RT-PCR) course was evaluated by regression analysis after the addition of different concentrations of tested microspheres to PCR mixtures. Microspheres mostly did not interfere in RT-PCR till the concentration 50 µg/25 µl PCR mixture. No relationship between Fe content (and microsphere diameter) and inhibition effect was found. Microspheres containing carboxyl groups extinguished the fluorescence at lower concentrations (10-20 µg/25 µl PCR mixture) without inhibition of DNA amplification as PCR products were detected using agarose gel electrophoresis. Negative effect of maghemite on PCR course was partially reduced by coating of magnetic core by silica or polymers. Two inhibition mechanisms of DNA amplification were discussed in this work.

  5. The use of polyethyleneglycolmethacrylate-co-vinylimidazole (PEGMA-co-VI) microspheres for the removal of nickel(II) and chromium(VI) ions.

    Science.gov (United States)

    Uğuzdoğan, Erdal; Denkbaş, Emir Baki; Kabasakal, Osman Sermet

    2010-05-15

    The polyethyleneglycolmethacrylate-co-vinylimidazole (PEGMA-VI) copolymers, that can be used in heavy metal removal applications, were synthesized and characterized; and their use as sorbents in heavy metal removal was investigated. It was determined that the ligand vinylimidazole was successfully inserted into the polymer structure. Then, chromium (Cr(VI)) and nickel (Ni(II)) ions were used as model species to investigate the usability of the obtained microspheres in heavy metal removal. The effects of pH of the adsorption medium, initial concentration of the metal ions and VI content of PEGMA-VI microspheres were investigated as the effective parameters on the adsorption capacities of the microspheres. The adsorption rate of the microspheres was also investigated for determination of the optimum adsorption time which is the required time for maximum adsorption capacity. The adsorption capacities under optimum conditions were also determined. The order of adsorption affinities of PEGMA-VI microspheres with respect to the used metals was determined by competitive adsorption studies. According to the obtained results, the highest adsorption affinity of the PEGMA-VI microspheres was towards Cr(VI) ions, the adsorption affinity was less for Ni(II) and the least affinity was towards Cu(II) ions. The adsorption-desorption studies showed that the microspheres were reusable without a significant decrease in the ion adsorption capacities. Copyright (c) 2009 Elsevier B.V. All rights reserved.

  6. Synthesis of high saturation magnetization superparamagnetic Fe3O4 hollow microspheres for swift chromium removal.

    Science.gov (United States)

    Liu, Yubiao; Wang, Yongqiang; Zhou, Shaomin; Lou, Shiyun; Yuan, Lin; Gao, Tao; Wu, Xiaoping; Shi, Xiaojing; Wang, Ke

    2012-09-26

    High saturation magnetization monodisperse Fe(3)O(4) hollow microspheres (109.48 emu/g) with superparamagnetic property at room temperature are promptly synthesized by a one-step solvothermal process with the presence of sodium dodecylbenzenesulfonate as an additive. The as-synthesized products possess superparamagnetism, large cavity, high water solubility, and saturation magnetization at room temperature. In particular, these hollow microspheres exhibit both of a rather short separation time from industry wastewater and a high adsorption capacity about 180 mg/g at high Cr(VI) concentrations, which is much better than those of reported magnetite solid nanoparticles. In addition, the X-ray photoelectron spectra (XPS) show that the uptake of Cr(VI) into the spheres was mainly governed by a physicochemical process. The micelle-assisted Ostwald ripening process was proposed to explain the rapid formation of hollow structures by a series of control experiments. The as-manufactured products with the two advantages mentioned above serve as ideal candidates for environmental remediation materials.

  7. Template-etching route to construct uniform rattle-type Fe3O4@SiO2 hollow microspheres as drug carrier.

    Science.gov (United States)

    Cheng, Lin; Liu, Yuanyuan; Zou, Bingfang; Yu, Yong; Ruan, Weimin; Wang, Yongqiang

    2017-06-01

    Template-etching strategy was put forward to synthesize rattle-type magnetic silica (Fe3O4@SiO2) hollow microspheres in a controlled way. During the experiment, monodisperse Fe2O3 microspheres were fabricated as physical template to generate uniform Fe2O3@SiO2 with controlled shell thicknesses through sol-gel method, and the subsequent Fe2O3 template etching process created variable space between Fe2O3 core and SiO2 shell, and the final calcination process transformed rattle-type Fe2O3@SiO2 hollow microspheres into corresponding Fe3O4@SiO2 product in hydrogen/nitrogen atmosphere. Compared with traditional physical template, here template-etching synthesis of rattle-type hollow microspheres saved the insertion of middle shells and their removal, which simplified the synthesis process with controllable core size and shell thickness. The rattle-type Fe3O4@SiO2 hollow microspheres as drug carrier show efficient doxorubicin (DOX) loading, and the release rate of DOX loaded the rattle-type Fe3O4@SiO2 hollow microspheres exhibit a surprising shell-thickness-dependent and a pH responsive drug release features. Additionally, MTT assays in HeLa cells demonstrated that the Fe3O4@SiO2 nanocarriers were non-toxic even at the concentration of 250µgmL(-1) for 48h. Thus, our results revealed that the Fe3O4@SiO2-DOX could play an important role in the development of intracellular delivery nanodevices for cancer therapy. Copyright © 2017. Published by Elsevier B.V.

  8. In vivo imaging of the morphology and changes in pH along the gastrointestinal tract of Japanese medaka by photonic band-gap hydrogel microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Du, Xuemin [Advanced Laboratory for Environmental Research and Technology, USTC-CityU, Suzhou 215123 (China); Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Centre for Functional Photonics, Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Lei, Ngai-Yu; Hu, Peng [Centre for Functional Photonics, Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Lei, Zhang; Ong, Daniel Hock-Chun [Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong (China); Ge, Xuewu [Advanced Laboratory for Environmental Research and Technology, USTC-CityU, Suzhou 215123 (China); Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Zhicheng, E-mail: zczhang@ustc.edu.cn [Advanced Laboratory for Environmental Research and Technology, USTC-CityU, Suzhou 215123 (China); Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Lam, Michael Hon-Wah, E-mail: bhmhwlam@cityu.edu.hk [Advanced Laboratory for Environmental Research and Technology, USTC-CityU, Suzhou 215123 (China); Centre for Functional Photonics, Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2013-07-17

    Graphical abstract: -- Highlights: •Fabrication of pH-responsive photonic colloidal crystalline microspheres. •Specific photonic band-gap responses occurred in the pH range of 4–5. •Remarkably low in vivo toxicity to Japanese medaka (Oryzia latipes). •In vivo imaging of the morphology and pH along GI tract of Japanese medaka. •Demonstrates bio-imaging potentials of stimuli-responsive photonic materials. -- Abstract: Colloidal crystalline microspheres with photonic band-gap properties responsive to media pH have been developed for in vivo imaging purposes. These colloidal crystalline microspheres were constructed from monodispersed core–shell nano-size particles with poly(styrene-co-acrylic acid) (PS-co-PAA) cores and poly(acrylic acid-co-N-isopropylacrylamide) (PAA-co-PNIPAM) hydrogel shells cross-linked by N,N′-methylenebisacrylamide. A significant shift in the photonic band-gap properties of these colloidal crystalline microspheres was observed in the pH range of 4–5. This was caused by the discontinuous volume phase transition of the hydrogel coating, due to the protonation/deprotonation of its acrylic acid moieties, on the core–shell nano-sized particles within the microspheres. The in vivo imaging capability of these pH-responsive photonic microspheres was demonstrated on a test organism – Japanese medaka, Oryzia latipes – in which the morphology and change in pH along their gastrointestinal (GI) tracts were revealed under an ordinary optical microscope. This work illustrates the potential of stimuli-responsive photonic band-gap materials in tissue-/organ-level in vivo bio-imaging.

  9. A Facile Solvothermal Synthesis of Monodisperse Ni Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    YU Peng-fei; CUI Bin; ZHANG Yan; SHI Qi-zhen

    2008-01-01

    A simple solvothermal approach was developed to synthesize uniform spherical monodisperse Ni nanoparticles, which can easily disperse in nonpolar solvents to form homogenous colloidal solution. The as-prepared sample was characterized by XRD, TEM, and FTIR. The results indicate that Ni nanoparticles have the structure of face-centered cube and a narrow distribution with a diameter of (3.5±0.5) nm. The FTIR spectrum reveals that the as a surfactant. The probable formation mechanism of the spherical nanoparticles was also discussed.

  10. Structural disorder versus spin canting in monodisperse maghemite nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Kubickova, S.; Vejpravova, J., E-mail: vejpravo@fzu.cz [Department of Magnetic Nanosystems, Institute of Physics of the ASCR, v.v.i., Na Slovance 2, 182 21 Prague (Czech Republic); Niznansky, D. [Faculty of Science, Department of Inorganic Chemistry, Charles University in Prague, Albertov 2030, 128 40 Prague (Czech Republic); Morales Herrero, M. P. [Instituto de Ciencia de Materiales de Madrid, CSIC, C/Sor Juana Ins de la Cruz 3, Campus de Cantoblanco, 28049 Madrid (Spain); Salas, G. [Instituto de Ciencia de Materiales de Madrid, CSIC, C/Sor Juana Ins de la Cruz 3, Campus de Cantoblanco, 28049 Madrid (Spain); Instituto Madrileno de Estudios Avanzados en Nanociencia, Campus Universitario de Cantoblanco, 28049 Madrid (Spain)

    2014-06-02

    Monodisperse maghemite nanoparticles with diameter ranging from 7 to 20 nm were examined by the In-field Mössbauer Spectroscopy (IFMS) in varying external magnetic field up to 6 T. Surprisingly, the small-sized particles (7 nm) exhibit nearly no spin canting in contrast to the larger particles with lower surface-to-volume ratio. We demonstrate that the observed phenomenon is originated by lower relative crystallinity of the larger particles with different internal structure. Hence, the persistence of the 2nd and 5th absorption lines in the IFMS cannot be unambiguously assigned to the surface spins.

  11. Monodisperse Silver Nanoparticles Synthesized by a Microwave-Assisted Method

    Institute of Scientific and Technical Information of China (English)

    ZHU Shao-Peng; TANG Shao-Chun; MENG Xiang-Kang

    2009-01-01

    Silver nanoparticles with an average size of about 2Onto are synthesized in a colloidal solution with the aid of microwave irradiation. Neither additional reductant nor stabilizer is required in this microwave-assisted method.The color of the colloidal solution is found to be dark green, different from the characteristic yellow of silver colloidal solutions. The silver nanoparticles in the colloidal solution have a narrow size distribution and large yield quantity. UV-visible absorption spectroscopy analysis reveals that the as-synthesized monodisperse silver nanoparticles have exceptional optical properties. Raman spectroscopy measurements demonstrate that these silver nanoparticles exhibit a notable surface-enhanced Raman scattering ability.

  12. MONODISPERSE MICRON-SIZED POLYACRYLAMIDE PARTICLES SYNTHESIZED BY DISPERSION POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Xin Hou; Bo Gao; Zhe-guo Zhang; Kang-de Yao

    2007-01-01

    Monodisperse micron-sized polyacrylamide (PAM) particles with a regular shape have been successfully prepared through dispersion polymerization of the monomer using a rotary reactor. FTIR and NMR spectroscopic results demonstrated the formation of PAM. POM and TEM observations revealed that PAM particles had a regular shape and good dispersity. A thick layer of surfactant (PVP) still existed on PAM particles after multiple centrifugation and ultrasonic re-dispersion in ethanol, which indicates a strong interaction between PVP and PAM. The effects of various polymerization factors on the average size of PAM particles have also been studied.

  13. Preparation of polyvinylpyrrodione microspheres by dispersion polymerization

    Institute of Scientific and Technical Information of China (English)

    Linfeng ZHAI; Tiejun SHI; Hualin WANG

    2009-01-01

    The preparation of polyvinylpyrrolidone (PVP) microspheres in ethyl acetate by dispersion polymerization with N-vinylpyrrolidone (NVP) as initial monomer, poly(N-vinylpyrrolidone-co-vinyl acetate) (P (NVP-co-VAc)) as dispersant, and 2, 2'-azobisisobutyr-onitrile(AIBN) as initiator is reported. The influences of monomer concentration, dispersant concentration and initiator concentration on the size of PVP microspheres as well as the monomer conversion were studied. The structure and properties of PVP microspheres were analyzed. The results show that the prepared PVP micro-spheres have a mean diameter of 3-4 μm. With an increase in NVP concentration, the size and the molecular weight of the PVP microspheres as well as the monomer conversion all increase. With increasing P(NVP-co-VAc) concentra-tions, the PVP molecular weight and monomer conversion both increase while the size of the microspheres becomes smaller. As the concentration of AIBN increases, the microsphere size and monomer conversion increase whereas the PVP molecular weight decreases. The PVP prepared by dispersion polymerization has a crystal structure, and its molecular weight is lower compared to that prepared by solution polymerization.

  14. Double-walled microspheres for the sustained release of a highly water soluble drug: characterization and irradiation studies.

    Science.gov (United States)

    Lee, Teng Huar; Wang, Jianjun; Wang, Chi-Hwa

    2002-10-30

    Composite double-walled microspheres with biodegradable poly(L-lactic acid) (PLLA) shells and poly(D,L-lactic-co-glycolic acid) (PLGA) cores were fabricated with highly water-soluble etanidazole entrapped within the core as solid crystals. This paper discusses the characterization, in vitro release and the effects of irradiation on this class of microsphere. Through the variation of polymer mass ratios, predictable shell and core dimensions could be fabricated and used to regulate the release rates. A direct and simple method was devised to determine the composition of the shell and core polymer based on the different solubilities of the polymer pair in ethyl acetate. A distribution theory based on solubility parameter explains why highly hydrophilic etanidazole has the tendency to be distributed consistently to the more hydrophilic polymer. Release profiles for normal double-walled samples have about 80% of drug released over 10 days after the initial time lag, while for irradiated double-walled samples, the sustained release lasted for more than 3 weeks. Although sustained release was short of the desired 6-8 weeks required for therapy, a low initial burst of less than 5% and time lags that can be manipulated, allows for administration of these microspheres together with traditional ones to generate pulsatile or new type of releases. The effects of irradiation were also investigated to determine the suitability of these double-walled microspheres as delivery devices to be used in conjunction with radiotherapy. Typical therapeutic dosage of 50 Gy was found to be too mild to have noticeable effects on the polymer and its release profiles, while, sterilization dosages of 25 kGy, lowered the glass transition temperatures and crystalline melting point, indirectly indicating a decrease in molecular weight. This accelerated degradation of the polymer, hence releasing the drug.

  15. Molecularly imprinted polymer beads for nicotine recognition prepared by RAFT precipitation polymerization: a step forward towards multifunctionalities

    OpenAIRE

    Zhou, Tongchang; Jørgensen, Lars; Mattebjerg, Maria Ahlm; Chronakis, Ioannis S; Ye, Lei

    2014-01-01

    A nicotine imprinted polymer was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization using methacrylic acid (MAA) as a functional monomer. The resulting molecularly imprinted polymers were monodispersed beads with an average diameter of 1.55 mm. The molecular selectivity of the imprinted polymer beads was evaluated by studying the uptake of nicotine and its structural analogs by the polymer beads. Equilibrium binding results indicate that the amount of nicoti...

  16. Polylactic-co-glycolic acid microspheres containing three neurotrophic factors promote sciatic nerve repair after injury

    Institute of Scientific and Technical Information of China (English)

    Qun Zhao; Zhi-yue Li; Ze-peng Zhang; Zhou-yun Mo; Shi-jie Chen; Si-yu Xiang; Qing-shan Zhang; Min Xue

    2015-01-01

    A variety of neurotrophic factors have been shown to repair the damaged peripheral nerve. However, in clinical practice, nerve growth factor, neurotrophin-3 and brain-derived neuro-trophic factor are all peptides or proteins that may be rapidly deactivated at the focal injury site;their local effective concentration time following a single medication cannot meet the required time for spinal axons to regenerate and cross the glial scar. In this study, we produced polymer sustained-release microspheres based on the polylactic-co-glycolic acid copolymer; the micro-spheres at 300-µm diameter contained nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor. Six microspheres were longitudinally implanted into the sciatic nerve at the anastomosis site, serving as the experimental group; while the sciatic nerve in the control group was subjected to the end-to-end anastomosis using 10/0 suture thread. At 6 weeks after implanta-tion, the lower limb activity, weight of triceps surae muscle, sciatic nerve conduction velocity and the maximum amplitude were obviously better in the experimental group than in the control group. Compared with the control group, more regenerating nerve ifbers were observed and dis-tributed in a dense and ordered manner with thicker myelin sheaths in the experimental group. More angiogenesis was also visible. Experimental findings indicate that polylactic-co-glycolic acid composite microspheres containing nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor can promote the restoration of sciatic nerve in rats after injury.

  17. Polylactic-co-glycolic acid microspheres containing three neurotrophic factors promote sciatic nerve repair after injury

    Directory of Open Access Journals (Sweden)

    Qun Zhao

    2015-01-01

    Full Text Available A variety of neurotrophic factors have been shown to repair the damaged peripheral nerve. However, in clinical practice, nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor are all peptides or proteins that may be rapidly deactivated at the focal injury site; their local effective concentration time following a single medication cannot meet the required time for spinal axons to regenerate and cross the glial scar. In this study, we produced polymer sustained-release microspheres based on the polylactic-co-glycolic acid copolymer; the microspheres at 300-μm diameter contained nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor. Six microspheres were longitudinally implanted into the sciatic nerve at the anastomosis site, serving as the experimental group; while the sciatic nerve in the control group was subjected to the end-to-end anastomosis using 10/0 suture thread. At 6 weeks after implantation, the lower limb activity, weight of triceps surae muscle, sciatic nerve conduction velocity and the maximum amplitude were obviously better in the experimental group than in the control group. Compared with the control group, more regenerating nerve fibers were observed and distributed in a dense and ordered manner with thicker myelin sheaths in the experimental group. More angiogenesis was also visible. Experimental findings indicate that polylactic-co-glycolic acid composite microspheres containing nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor can promote the restoration of sciatic nerve in rats after injury.

  18. Enhanced in vitro dissolution of Iloperidone using Caesalpinia Pulcherrima mucoadhesive microspheres

    Directory of Open Access Journals (Sweden)

    Pradum Pundlikrao Ige

    2015-03-01

    Full Text Available The aim of the present investigation was to improve the solubility and dissolution rate of Iloperidone. Microspheres containing Iloperidone were prepared by spray drying using mucilage extracted from seeds of Caesalpinia pulcherrima. The novelty of this work is that, the extraction of mucilage and its usage for preparation of drug loaded microspheres. The prepared microspheres were characterized by SEM, DSC, XRPD, FTIR, 1H-NMR, particle size, drug content, entrapment efficiency, in vitro dissolution and ex vivo mucoadhesion. Based on particle size, drug content, ex vivo mucoadhesive strength and in vitro drug release, the best formulation was optimized. Percent entrapment efficiency and mean particle size for optimized formulation was found to be 73.49 and 3.27 ± 1.23 μm, respectively. More precisely, mucilage of C. pulcherrima could be significant carrier of (drug and polymer ratio 1:5 microspheres for the development of oral drug delivery.

  19. Synthesis, characterisation and drug release properties of microspheres of polystyrene with aliphatic polyester side-chains.

    Science.gov (United States)

    Kukut, Manolya; Karal-Yilmaz, Oksan; Yagci, Yusuf

    2014-01-01

    A series of graft copolymers consisting of polystyrene backbone with biocompatible side chains based on (co)polymers of l-lactic acid and glycolic acid were synthesised by combination two controlled polymerisations, namely, nitroxide mediated radical polymerisation (NMRP) and ring opening polymerisation (ROP) with "Click" chemistry. The main goal of this work was to design new biodegradable microspheres using obtained graft copolymers for long-term sustained release of imatinib mesylate (IMM) as a model drug. The IMM loaded microspheres of the graft copolymers, polystyrene-g-poly(lactide-co-glycolide) (PS-g-PLLGA), polystyrene-g-poly(lactic acid) (PS-g-PLLA) and poly(lactic-coglycolic acid) (PLLGA) were then prepared by a modified water-in-oil-in-water (w1/o/w2) double emulsion/solvent evaporation technique. The optimised microspheres were characterised by particle size, encapsulation efficiency, and surface morphology also; their degradation and release properties were studied in vitro. The degradation studies of three different types of microspheres showed that the PS backbone of the graft copolymers slows down the degradation rate compared to PLLGA.

  20. Influence of Formulation Components on Aerosolization Properties of Isoniazid Loaded Chitosan Microspheres

    Directory of Open Access Journals (Sweden)

    Aliasgar J. Kundawala

    2011-10-01

    Full Text Available The objective of the present study was to prepare microspheres with small size and good sphericity by spray drying technology using Isoniazid (INH as model drug, chitosan as encapsulating polymer; lactose and L Leucine as bulking and dispersing agent respectively. Influence of formulation components on physical properties and aerosol performance were studied. The spray dried powders obtained were characterized for morphological characteristics, compatibility using scanning electron microscopy and Differential Scanning calorimetery respectively. Tapped density; bulk density and aerosol properties like Fine particle fraction, mass median aerodynamic diameter etc were also evaluated. The smooth microspheres with particle size ranging between 4 to 6 µm were obtained. The drug content of chitosan microspheres loaded with Isoniazid were in the range of 88 % to 108 %. The drug release studies showed that more than 90% of drug released from the chitosan microsphere matrix within one hour. The fine particle fraction observed between 55 to 67 % which indicate good lung deposition. Results of Fine particle fraction also revealed addition of L Leucine found to enhance powder dispersibility.

  1. Synthesis of polycaprolactone/nano hydroxyapatite microspheres; Sintese de microesferas de policaprolactona/nanohidroxiapatita

    Energy Technology Data Exchange (ETDEWEB)

    Sampaio, Greyce Y.H.; Souza, Mairly K. da S.; Melo, Rafaela Q. da C.; Carrodeguas, Raul G.; Fook, Marcus V.L., E-mail: greycesampaio@gmail.com [Universidade Federal de Campina Grande (UFCG), Campina Grande, PB (Brazil)

    2013-07-01

    Polycaprolactone(PCL)/nano hydroxyapatite(nHA) microspheres are advantageous material for manufacturing tridimensional scaffolds and formulating drug delivery systems for bone regeneration. The work was aimed to study the effect of processing variables on the properties of PCL/nHA microspheres. nHA was produced by precipitation method and was obtained calcium deficient nanoparticles consisted of nanorods (∼47 nm x ∼8 nm), according to the results of XRD, FTIR and TEM. PCL/nHA microspheres was produced by solid-in-oil-in-water emulsion solvent evaporation method. The variables studied were concentration of PCL (5,7.5 and 10 % w/v), nHA addition (17, 23 and 28.5% m/m) and surface treatment of nHA with stearic acid (AE). PCL/nHA microspheres were characterized by XRD, FTIR, SEM and TGA. The best result was obtained with a PCL concentration of 10% (w/v) and 23 % (m/m) of modified nHA. Solid PCL/nHA particles ranging 30-70 μm and containing 14 % of nHA dispersed in the polymer matrix were obtained, with agglomerates of nHA raging 5 -15 μm. These results suggest the promising use of this material in bone regeneration devices. (author)

  2. Introduction of enzymatically degradable poly(trimethylene carbonate) microspheres into an injectable calcium phosphate cement.

    Science.gov (United States)

    Habraken, Wouter J E M; Zhang, Zheng; Wolke, Joop G C; Grijpma, Dirk W; Mikos, Antonios G; Feijen, Jan; Jansen, John A

    2008-06-01

    Poly(trimethylene carbonate) (PTMC) is an enzymatically degradable polyester with rubber-like properties. Introduction of this polymer into an injectable calcium phosphate bone cement can therefore be used to introduce macroporosity into the cement for tissue engineering purposes as well as to improve mechanical properties. Aim of this study was to investigate calcium phosphate cements with incorporated PTMC microspheres (PTMC CPCs) on their physical/mechanical properties and in vitro degradation characteristics. Therefore, composites were tested on setting time and mechanical strength as well as subjected to phosphate buffered saline (PBS) and enzyme containing medium. PTMC CPCs (12.5 and 25 wt%) with molecular weights of 52.7 kg mol(-1) and 176.2 kg mol(-1) were prepared, which showed initial setting times similar to that of original CPC. Though compression strength decreased upon incorporation of PTMC microspheres, elastic properties were improved as strain-at-yield increased with increasing content of microspheres. Sustained degradation of the microspheres inside PTMC CPC occurred when incubated in the enzymatic environment, but not in PBS, which resulted in an interconnected macroporosity for the 25 wt% composites.

  3. Polylactic-co-glycolic acid microspheres containing three neurotrophic factors promote sciatic nerve repair after injury.

    Science.gov (United States)

    Zhao, Qun; Li, Zhi-Yue; Zhang, Ze-Peng; Mo, Zhou-Yun; Chen, Shi-Jie; Xiang, Si-Yu; Zhang, Qing-Shan; Xue, Min

    2015-09-01

    A variety of neurotrophic factors have been shown to repair the damaged peripheral nerve. However, in clinical practice, nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor are all peptides or proteins that may be rapidly deactivated at the focal injury site; their local effective concentration time following a single medication cannot meet the required time for spinal axons to regenerate and cross the glial scar. In this study, we produced polymer sustained-release microspheres based on the polylactic-co-glycolic acid copolymer; the microspheres at 300-μm diameter contained nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor. Six microspheres were longitudinally implanted into the sciatic nerve at the anastomosis site, serving as the experimental group; while the sciatic nerve in the control group was subjected to the end-to-end anastomosis using 10/0 suture thread. At 6 weeks after implantation, the lower limb activity, weight of triceps surae muscle, sciatic nerve conduction velocity and the maximum amplitude were obviously better in the experimental group than in the control group. Compared with the control group, more regenerating nerve fibers were observed and distributed in a dense and ordered manner with thicker myelin sheaths in the experimental group. More angiogenesis was also visible. Experimental findings indicate that polylactic-co-glycolic acid composite microspheres containing nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor can promote the restoration of sciatic nerve in rats after injury.

  4. Monodispersed magnetite nanoparticles optimized for magnetic fluid hyperthermia: Implications in biological systems

    Science.gov (United States)

    Khandhar, Amit P.; Ferguson, R. Matthew; Krishnan, Kannan M.

    2011-04-01

    Magnetite (Fe3O4) nanoparticles (MNPs) are suitable materials for Magnetic Fluid Hyperthermia (MFH), provided their size is carefully tailored to the applied alternating magnetic field (AMF) frequency. Since aqueous synthesis routes produce polydisperse MNPs that are not tailored for any specific AMF frequency, we have developed a comprehensive protocol for synthesizing highly monodispersed MNPs in organic solvents, specifically tailored for our field conditions (f = 376 kHz, H0 = 13.4 kA/m) and subsequently transferred them to water using a biocompatible amphiphilic polymer. These MNPs (σavg. = 0.175) show truly size-dependent heating rates, indicated by a sharp peak in the specific loss power (SLP, W/g Fe3O4) for 16 nm (diameter) particles. For broader size distributions (σavg. = 0.266), we observe a 30% drop in overall SLP. Furthermore, heating measurements in biological medium [Dulbecco's modified Eagle medium (DMEM) + 10% fetal bovine serum] show a significant drop for SLP (˜30% reduction in 16 nm MNPs). Dynamic Light Scattering (DLS) measurements show particle hydrodynamic size increases over time once dispersed in DMEM, indicating particle agglomeration. Since the effective magnetic relaxation time of MNPs is determined by fractional contribution of the Neel (independent of hydrodynamic size) and Brownian (dependent on hydrodynamic size) components, we conclude that agglomeration in biological medium modifies the Brownian contribution and thus the net heating capacity of MNPs.

  5. Preparation of Size-tunable, Highly Monodisperse PVP-Protected Pt-nanoparticles by Seed-mediated Growth

    Energy Technology Data Exchange (ETDEWEB)

    Koebel, Matthias Michael; Jones, Louis C.; Somorjai, Gabor A.

    2008-04-02

    We demonstrate a preparative method which produces highly-monodisperse Pt-nanoparticles of tunable size without the external addition of seed particles. Hexachloroplatinic acid is dosed slowly to an ethylene glycol solution at 120 C and reduced in the presence of a stabilizing polymer poly-N-vinylpyrollidone (PVP). Slow addition of the Pt-salt first will first lead to the formation of nuclei (seeds) which then grow further to produce larger particles of any desired size between 3 and 8nm. The amount of added hexachloroplatinic acid precursor controls the size of the final nanoparticle product. TEM was used to determine size and morphology and to confirm the crystalline nature of the nanoparticles. Good reproducibility of the technique was demonstrated. Above 7nm, the particle shape and morphology changes suddenly indicating a change in the deposition selectivity of the Pt-precursor from (100) towards (111) crystal faces and breaking up of larger particles into smaller entities.

  6. A novel method for preparing monodispersed polystyrene nanoparticles

    Institute of Scientific and Technical Information of China (English)

    LIU Kaiyi; WANG Zhaoqun

    2007-01-01

    A preparation manner for monodispersed polystyrene(PS)nanoparticles polymerized by using a novel addition procedure of a monomer is suggested.In systems containing a smaller amount of surfactant compared with conventional microemulsion polymerization,the polymerization processes consists of three stages:adding dropwise the first part of the monomer for a few minutes at 80℃ and polymerizing for 1 h;adding collectively the residual part of the monomer and polymerizing at the same temperature for another 1 h;and then polymerizing at 85℃ for another 1 h.Based on discussions on the nucleation mechanism of particles in the polymerization system,the influences of monomer weight added dropwise,and amounts of initiator and emulsifier on the size and distribution of PS particles were investigated.PS nanoparticles with smaller diameter such as a number-average diameter of 18.7 nm and better monodispersity were obtained since the dropped styrene amount was suitable under 20wt-% emulsifier amount and 3wt-% initiator amount based on the monomer.

  7. 载Fe3O4高分子微球联合高强度聚焦超声损伤兔乳腺移植瘤的实验研究%Experiment study of Fe3O4-loaded polymer microspheres for combining with high-intensity focused ultrasound to damage breast cancer of rabbits

    Institute of Scientific and Technical Information of China (English)

    孙阳; 郑元义; 周洋; 沈红霞; 王琦; 王志刚

    2012-01-01

    Objective To prepare the Fe3O4 loaded polymer microspheres(Fe3O4/PLGA),and to investigate the influence of Fe3O4/PLGA combined with high-intensity focused ultrasound (HIFU) on rabbits bearing breast tumor.Methods Double emulsion method were utilized to prepare the Fe3O4/PLGA.14 days after implantation of VX2 tumor in breast,32 rabbits were randomly divided into four equal groups.In group Ⅱ,Ⅲ,and Ⅳ,the rabbits received a percutaneous injection of 0.5 ml saline,PLGA,and Fe3O4/PLGA microcapsules solution into breast tumor at 3,6,9,12 dots,about 3 mm around the tumor respectively,and massaged for 1 min before receiving HIFU ablation,while HIFU group received HIFU ablation only.HIFU ablation parameters were the same:"ablated-dot" mode,acoustic power 150 W,exposure duration 5 s.After HIFU ablation,the volume of coagulative necrosis was calculated,HE staining,TEM and immunohistochemical examination of PCNA were performed to detect the structure changes of the targeted tissue caused by HIFU ablation.Results The volume of coagulative necrosis caused by HIFU ablation was substantially larger and the positive index of PCNA was lower in the necrotic region after the injection of Fe3O4/PLGA microcapsules compared to the group without injection agents,the group of saline and the group of pure PLGA microspheres under the same irritation(P <0.05).Pathological examination demonstrated the targeted tissue was destroyed severely,Fe3O4 nanoparticles were seen depositing in residual tumor cells under TEM.Conclusions The self-made Fe3O4/PLGA microspheres can effectively enhanced the biomedical effect of HIFU surgery on rabbits bearing VX2 breast tumor.%目的 探讨自制载氧化铁高分子微球(Fe3O4/PLGA)联合高强度聚焦超声(HIFU)对兔VX2乳腺癌消融效果的影响.方法 双乳化法制备载Fe3O4的高分子微球.建立兔VX2乳腺癌模型32只,于肿瘤接种后14d,随机分为4组,第1组实验兔给予单纯HIFU辐照;第2、3、4组

  8. 聚苯乙烯/二氧化锰复合微球的合成与表征%Synthesis and characterization of polystyrene/β-manganese dioxide organic/inorganic composite microspheres

    Institute of Scientific and Technical Information of China (English)

    张艳萍; 钱建华; 刘琳; 王莉丽; 王晓旭

    2012-01-01

    Uniform polystyrene/β-manganese dioxide organic/inorganic composite microspheres were prepared by an easy and economical approach.Monodispersed sulfonated polystyrene(PS) microspheres were used as templates as well as the core of the composite microspheres,the shell layers were consist of close accumulated manganese dioxide nanorods and obtained through a hydrothermal reaction of Mn (CH3COO)2 and ammonium persulfate ((NH4)2S2O8) at 140℃.Scanning electron microscopy(SEM) and transmission electron microscopy(TEM)studies show that the as-obtained products consist of large scale composite microspheres.A possible mechanism for the formation of composite microspheres is also proposed in the paper.%本文利用聚苯乙烯微球为模板水热合成了聚苯乙烯/二氧化锰有机无机复合微球.复合微球核层为聚苯乙烯微球,壳层是由大量的二氧化锰纳米棒紧密堆积形成的.利用扫描电子显微镜及透射电子显微镜表征可以看出产物含有大量的复合微球,对于可能的反应机理进行了讨论.

  9. Composite CD-MOF nanocrystals-containing microspheres for sustained drug delivery.

    Science.gov (United States)

    Li, Haiyan; Lv, Nana; Li, Xue; Liu, Botao; Feng, Jing; Ren, Xiaohong; Guo, Tao; Chen, Dawei; Fraser Stoddart, J; Gref, Ruxandra; Zhang, Jiwen

    2017-06-08

    Metal-organic frameworks (MOFs), which are typically embedded in polymer matrices as composites, are emerging as a new class of carriers for sustained drug delivery. Most of the MOFs and the polymers used so far in these composites, however, are not pharmaceutically acceptable. In the investigation reported herein, composites of γ-cyclodextrin (γ-CD)-based MOFs (CD-MOFs) and polyacrylic acid (PAA) were prepared by a solid in oil-in-oil (s/o/o) emulsifying solvent evaporation method. A modified hydrothermal protocol has been established which produces efficiently at 50 °C in 6 h micron (5-10 μm) and nanometer (500-700 nm) diameter CD-MOF particles of uniform size with smooth surfaces and powder X-ray diffraction patterns that are identical with those reported in the literature. Ibuprofen (IBU) and Lansoprazole (LPZ), both insoluble in water and lacking in stability, were entrapped with high drug loading in nanometer-sized CD-MOFs by co-crystallisation (that is more effective than impregnation) without causing MOF crystal degradation during the loading process. On account of the good dispersion of drug-loaded CD-MOF nanocrystals inside polyacrylic acid (PAA) matrices and the homogeneous distribution of the drug molecules within these crystals, the composite microspheres exhibit not only spherical shapes and sustained drug release over a prolonged period of time, but they also demonstrate reduced cell toxicity. The cumulative release rate for IBU (and LPZ) follows the trend: IBU-γ-CD complex microspheres (ca. 80% in 2 h) > IBU microspheres > IBU-CD-MOF/PAA composite microspheres (ca. 50% in 24 h). Importantly, no burst release of IBU (and LPZ) was observed from the CD-MOF/PAA composite microspheres, suggesting an even distribution of the drug as well as strong drug carrier interactions inside the CD-MOF. In summary, these composite microspheres, composed of CD-MOF nanocrystals embedded in a biocompatible polymer (PAA) matrix, constitute an efficient and

  10. Characterization of a Polyamine Microsphere and Its Adsorption for Protein

    Directory of Open Access Journals (Sweden)

    Huixian Wei

    2012-12-01

    Full Text Available A novel polyamine microsphere, prepared from the water-in-oil emulsion of polyethylenimine, was characterized. The investigation of scanning electron microscopy showed that the polyamine microsphere is a regular ball with a smooth surface. The diameter distribution of the microsphere is 0.37–4.29 μm. The isoelectric point of the microsphere is 10.6. The microsphere can adsorb proteins through the co-effect of electrostatic and hydrophobic interactions. Among the proteins tested, the highest value of adsorption of microsphere, 127.8 mg·g−1 microsphere, was obtained with lipase. In comparison with other proteins, the hydrophobic force is more important in promoting the adsorption of lipase. The microsphere can preferentially adsorb lipase from an even mixture of proteins. The optimum temperature and pH for the selective adsorption of lipase by the microsphere was 35 °C and pH 7.0.

  11. Monodisperse Femto- to Atto-liter Droplet Formation Using a Nano-Microchannel Interface

    NARCIS (Netherlands)

    Shui, Lingling; Berg, van den Albert; Eijkel, Jan C.T.; Kim, Tae Song; Lee, Yoon-Sik; Chung, Taek-Dong; Jeon, Noo Li; Suh, Kahp-Yang; Choo, Jaebum; Kim, Yong-Kweon

    2009-01-01

    We demonstrate the production of sub-micrometer diameter monodisperse droplets by using a nano-micro channel interface. A perfectly steady nanoscopic liquid filament can be formed by a geometric confinement which eventually gives rise to a stable production of nearly perfectly monodisperse droplets.

  12. Surface properties of poly(ethylene oxide)-based segmented block copolymers with monodisperse hard segments

    NARCIS (Netherlands)

    Husken, D.; Feijen, Jan; Gaymans, R.J.

    2009-01-01

    The surface properties of segmented block copolymers based on poly(ethylene oxide) (PEO) segments and monodisperse crystallizable tetra-amide segments were studied. The monodisperse crystallizable segments (T6T6T) were based on terephthalate (T) and hexamethylenediamine (6). Due to the crystallinity

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

    Directory of Open Access Journals (Sweden)

    Yuan W

    2012-01-01

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

  14. Self-assembly of CdSe quantum dots and colloidal titanium dioxide on copolymer microspheres (PS) for CdSe/PS and TiO2/CdSe/PS sub-microspheres with yolk-shell structure

    Science.gov (United States)

    Zhao, Qingchun

    2015-07-01

    Semiconductor nanocrystals serve as the building blocks for designing next generation solar cells, chemical/biological sensors, and metal chalcogenides (e.g., CdS, CdSe, PbS, and PbSe) are particularly useful for harnessing size-dependent optical and electronic properties in nanostructures. In this paper, relying on the interaction including van der Waals forces and hydrogen bond, CdSe/PS sub-microspheres composite and TiO2/CdSe/PS sub-microspheres with yolk-shell structure were prepared via self-assembly of CdSe quantum dots and colloidal titanium dioxide on modified PS surface. The morphology, structure and composition obtained products were investigated by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and energy disperse X-ray spectroscopy (EDX). Transmission electron microscopy (TEM) investigations show the CdSe quantum dots and colloidal titanate were assembled on the surface of PS sub-microspheres. CdSe QD-polymer sub-microspheres composites in which the QDs retain their original emission efficiency can be obtained. TiO2/CdSe/PS sub-microspheres with yolk-shell structure can improve the efficiency of charge separation.

  15. Fabrication of Phase-Change Polymer Colloidal Photonic Crystals

    Directory of Open Access Journals (Sweden)

    Tianyi Zhao

    2014-01-01

    Full Text Available This paper presents the preparation of phase-change polymer colloidal photonic crystals (PCs by assembling hollow latex spheres encapsulated with dodecanol for the first time. The monodispersed hollow latex spheres were obtained by phase reversion of monodispersed core-shell latex spheres in the n-hexane, which dissolves the PS core and retains the PMMA/PAA shell. The as-prepared phase-change colloidal PCs show stable phase-change behavior. This fabrication of phase-change colloidal PCs would be significant for PC’s applications in functional coatings and various optic devices.

  16. From Gelation and Glass Transition of Colloidal Systems to Polymers

    Science.gov (United States)

    Han, Charles; Yuan, Guangcui; Cheng, He

    Charles C. Han, Guangcui Yuan and He Cheng Joint Laboratory of Polymer Science and Materials, ICCAS, Beijing, China and Institute for Advanced Study, Shenzhen University, Shenzhen, China Aggregation and gelation behavior of mixed suspensions of polystyrene microspheres and poly(N-isopropylacrylamide) microgels have been studied. In dilute microsphere suspensions, with increasing concentration of microgel (MG), microspheres (MS) first aggregated with each other through the bridging of the microgels, then dispersed individually when saturated adsorption was achieved, and finally depletion clusters formed at even higher concentrations of microgel. In concentrated microsphere suspensions, with saturated MG adsorption, a state transition from attractive glass to repulsive glass can be observed. This type of system can be viewed as a molecular model system which has a long range repulsive interaction potential and a short range attractive potential. A comparison between the glass transition of the colloidal systems and the glass transition of polymeric systems can be made.

  17. Novel tamarind seed polysaccharide-alginate mucoadhesive microspheres for oral gliclazide delivery: in vitro-in vivo evaluation.

    Science.gov (United States)

    Pal, Dilipkumar; Nayak, Amit Kumar

    2012-04-01

    Novel tamarind seed polysaccharide (TSP)-alginate mucoadhesive microspheres were prepared using TSP and alginate as blend in different ratios with different calcium chloride (CaCl(2)) concentration as a cross linker by ionotropic gelation. The prepared microspheres were of spherical shape having rough surfaces, and average particle sizes within the range of 752.12 ± 6.42 to 948.49 ± 20.92 µm. The drug entrapment efficiency of these microspheres were within the range between 58.12 ± 2.42 to 82.78 ± 3.43% w/w. Fourier transform infrared (FTIR) studies indicated that there were no reactions between gliclazide, and polymers (TSP, and sodium alginate) used. Different formulations of gliclazide loaded TSP-alginate microspheres showed prolonged in vitro release profiles of gliclazide over 12 hours in both stomach pH (pH 1.2), and intestinal pH (pH 7.4). It was found that the gliclazide release in gastric pH was comparatively slow and sustained than intestinal pH. These TSP-alginate microspheres also exhibited good mucoadhesivity. The in vivo studies on alloxan-induced diabetic rats (Animal Ethical Committee registration number: IFTM/837ac/0160) demonstrated the significant hypoglycemic effect of selected formulation of TSP-alginate mucoadhesive microspheres containing gliclazide on oral administration. This developed gliclazide loaded new TSP-alginate mucoadhesive microspheres may be very much useful for prolonged systemic absorption of gliclazide for proper maintaining blood glucose level and advanced patient compliance.

  18. Highly reusability surface loaded metal particles magnetic catalyst microspheres (MCM-MPs) for treatment of dye-contaminated water

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying; Zhang, Kun, E-mail: kun4219@njtech.edu.cn; Yin, Xiaoshuang; Yang, Wenzhong; Zhu, Hongjun

    2016-04-01

    The metal-deposited magnetic catalyst microspheres (MCM-MPs) were successfully synthesized by one facile, high yield and controllable approach. Here, the bare magnetic microspheres were firstly synthesized according to the solvothermal method. Then silica shell were coated on the surface of the magnetic microspheres via sol–gel method, and subsequently with surface modifying with amino in the purpose to form SiO{sub 2}–NH{sub 2} shell. Thus, metal particles were easily adsorbed into the SiO{sub 2}–NH{sub 2} shell and in-situ reduced by NaBH{sub 4} solution. All the obtained products (MCM-Cu, MCM-Ag, MCM-Pd) which were monodisperse and constitutionally stable were exhibited high magnetization and excellent catalytic activity towards dyes solution reduction. The catalytic rate ratio of MCM-Pd: MCM-Cu: MCM-Ag could be 10:3:1. Besides, some special coordination compound Cu{sub 2}(OH){sub 3}Br had been generated in the in-situ reduced process of MCM-Cu, which produced superior cyclical stability (>20 times) than that of MCM-Ag and MCM-Pd. In all, those highly reusability and great catalytic efficiency of MCM-MPs show promising and great potential for treatment of dye-contaminated water. - Graphical abstract: Surface loaded metal particles magnetic catalyst microspheres MCM-MPs for rapid decolorizing dye-contaminated water: Synthesis, characterization and possible mechanisms. - Highlights: • A simple and high yield synthetic method for fabricate multi MCM-MPs is proposed with adequately optimize. • The highest reusability of MCM-Cu is attribute to the coordination compounds Cu{sub 2}(OH){sub 3}Br. • MCM-MPs show excellent catalytic properties under different situations for various dyes • The catalytic mechanism of MCM-MPs is presented.

  19. Organic aerogel microspheres and fabrication method therefor

    Science.gov (United States)

    Mayer, Steven T.; Kong, Fung-Ming; Pekala, Richard W.; Kaschmitter, James L.

    1996-01-01

    Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  20. Amidated pectin/sodium carboxymethylcellulose microspheres as a new carrier for colonic drug targeting: Development and optimization by factorial design.

    Science.gov (United States)

    Gadalla, Hytham H; El-Gibaly, Ibrahim; Soliman, Ghareb M; Mohamed, Fergany A; El-Sayed, Ahmed M

    2016-11-20

    The colon is a promising site for drug targeting owing to its long transit time and mild proteolytic activity. The aim of this study was to prepare new low methoxy amidated pectin/NaCMC microspheres cross-linked by a mixture of Zn(2+) and Al(3+) ions and test their potential for colonic targeting of progesterone. A 2(4) factorial design was carried out to optimize the preparation conditions. High drug entrapment efficiency (82-99%) was obtained and it increased with increasing drug concentration but decreased with increasing polymer concentration. Drug release rate was directly proportional to the microsphere drug content and inversely related to Al(3+) ion concentration. Drug release was minimal during the first 3h but was significantly improved in the presence of 1% rat caecal contents, confirming the microsphere potential for colonic delivery. The microspheres achieved >2.3-fold enhancement of colonic progesterone permeability. These results confirm the viability of the produced microspheres as colon-targeted drug delivery vehicle.

  1. Fabrication of flower-like tin/carbon composite microspheres as long-lasting anode materials for lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Tae-Woo [Department of Chemical Engineering, College of Engineering, Hanyang University, Seoul, 133-791 (Korea, Republic of); Lim, Hyung-Seok [Department of WCU Engineering, College of Engineering, Hanyang University, Seoul, 133-791 (Korea, Republic of); Park, Seong-Jin [Department of Chemical Engineering, College of Engineering, Hanyang University, Seoul, 133-791 (Korea, Republic of); Sun, Yang-Kook [Department of WCU Engineering, College of Engineering, Hanyang University, Seoul, 133-791 (Korea, Republic of); Suh, Kyung-Do, E-mail: kdsuh@hanyang.ac.kr [Department of Chemical Engineering, College of Engineering, Hanyang University, Seoul, 133-791 (Korea, Republic of)

    2017-01-01

    In this work, we report the fabrication of the flower-like tin/carbon (Sn/C) composite microspheres using sulfonated semi-interpenetrating polystyrene (SPS) microspheres as a carbon precursor. The sulfonation degree of SPS has great effects on the resulting particle size, morphology, amount of introduced Sn, and the carbonization yield of the microspheres after heat treatment. The obtained Sn/C composite microspheres were characterized by scanning electron microscopy (SEM), focused-ion beam SEM, and X-ray diffraction. The flower-like Sn/C composite electrodes exhibited higher charge-discharge capacities than those of graphite as an anode material for a lithium ion battery. In addition, they show a long lasting cyclability, even through 400 cycles. - Highlights: • Tin nanocrystals are introduced in flower-like carbon spheres with many ripples. • Long lasting cyclability is exhibited at 1 C rate up to 400 cycles. • Tin content of composite spheres depends on chemical treatment of polymer microspheres.

  2. Encapsulation of superparamagnetic iron oxide nanoparticles in poly-(lactide-co-glycolic acid) microspheres for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Gun, Sumeyra; Edirisinghe, Mohan [Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE (United Kingdom); Stride, Eleanor, E-mail: Eleanor.stride@eng.ox.ac.uk [Institute of Biomedical Engineering, Department of Engineering Science, Old Road Campus, University of Oxford, Oxford OX3 7DQ (United Kingdom)

    2013-08-01

    Magnetic microspheres were prepared using a single step coaxial electrohydrodynamic atomization technique at ambient temperature and pressure, with poly(lactic-co-glycolic acid) as the coating and iron oxide (Fe{sub 3}O{sub 4}) nanoparticles dispersed in polyethylene glycol as the encapsulated material. The morphology and particle size distributions of the prepared magnetic microspheres were investigated by scanning electron microscopy. The particles were spherical with mean diameters ranging from ∼ 2 μm to 18 μm, depending on the combination of processing parameters (flow rate and applied voltage). Analysis by infrared spectroscopy and focused ion-beam sectioning confirmed incorporation of iron oxide nanoparticles into the microspheres and the prepared samples were shown to be responsive to an applied magnetic field. This study demonstrates a convenient method for the preparation of nanoparticle loaded microspheres, which could be used potentially as transverse relaxation contrast agents in magnetic resonance imaging, as well as for magnetically guided drug delivery. Highlights: • Polymer microspheres embedding magnetic nanoparticles were prepared by coaxial electrospraying. • Particle size and uniformity could be controlled by varying the processing parameters. • Superparamagnetic characteristics were retained. • Particle formation required a single processing step at ambient temperature and pressure.

  3. N-(furfural) chitosan hydrogels based on Diels-Alder cycloadditions and application as microspheres for controlled drug release.

    Science.gov (United States)

    Montiel-Herrera, Marcelino; Gandini, Alessandro; Goycoolea, Francisco M; Jacobsen, Neil E; Lizardi-Mendoza, Jaime; Recillas-Mota, Maricarmen; Argüelles-Monal, Waldo M

    2015-09-01

    In this study, chitosan was chemically modified by reductive amination in a two-step process. The synthesis of N-(furfural) chitosan (FC) was confirmed by FT-IR and (1)H NMR analysis, and the degrees of substitution were estimated as 8.3 and 23.8%. The cross-linkable system of bismaleimide (BM) and FC shows that FC shared properties of furan-maleimide chemistry. This system produced non-reversible hydrogel networks by Diels-Alder cycloadditions at 85 °C. The system composed of BM and FC (23.8% substitution) generated stronger hydrogel networks than those of FC with an 8.3% degree of substitution. Moreover, the FC-BM system was able to produce hydrogel microspheres. Environmental scanning electron microscopy revealed the surface of the microspheres to be non-porous with small protuberances. In water, the microspheres swelled, increasing their volume by 30%. Finally, microspheres loaded with methylene blue were able to release the dye gradually, obeying second-order kinetics for times less than 600 min. This behavior suggests that diffusion is governed by the relaxation of polymer chains in the swelled state, thus facilitating drug release outside the microspheres.

  4. Hydrogen transport and storage in engineered microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Rambach, G. [Lawrence Livermore National Lab., CA (United States); Hendricks, C. [W.J. Schafer Associates, Livermore, CA (United States)

    1996-10-01

    This project is a collaboration between Lawrence Livermore National Laboratory (LLNL) and W.J. Schafer Associates (WJSA). The authors plan to experimentally verify the performance characteristics of engineered glass microspheres that are relevant to the storage and transport of hydrogen for energy applications. They will identify the specific advantages of hydrogen transport by microspheres, analyze the infrastructure implications and requirements, and experimentally measure their performance characteristics in realistic, bulk storage situations.

  5. Formulation and evaluation of controlled release floating microspheres of tolperisone hydrochloride

    Directory of Open Access Journals (Sweden)

    Pooja Jani

    2012-01-01

    Full Text Available Main aim of this study was to develop controlled release (CR floating multiparticulate drug delivery system of tolperisone hydrochloride. Microspheres were prepared by nonaqueous solvent evaporation technique consisting of porous calcium silicate (Florite or FLR as porous carrier, tolperisone hydrochloride (API, Ethyl cellulose (EC, and HPMC 15 cPs as rate controlling polymers. 2 3 full factorial design was applied for optimization of formulation. The effect of various formulation and process variables on the particle morphology, micromeritic properties, in vitro floating behavior, entrapment efficiency, and in vitro drug release were studied. The size of microspheres was varied from 300 to 500 μm. The microspheres were found to be highly porous and regular in shape. All the formulations showed excellent flow properties. The percentage entrapment efficiency of all batches was greater than 80%. The percentage buoyancy varied from 85% to 98% at the end of 12 h. The release rate was determined in simulated gastric fluids. The formulation demonstrated favorable in vitro floating and release characteristics. Different kinetic models were applied to study the release mechanism. All formulations followed Higuchi model, which indicates the diffusion control release of water soluble drug from polymer matrix. Multiple regression analysis was applied for study of the effect of independent variables on the dependent variables.

  6. A multiple unit floating drug delivery system of piroxicam using eudragit polymer

    Directory of Open Access Journals (Sweden)

    Kale R

    2007-01-01

    Full Text Available A floating drug delivery system of piroxicam in the form of microspheres was prepared using an enteric polymer and emulsification solvent-evaporation method. The microspheres remained buoyant continuously over the surface of acidic media containing surfactant for a period of 8-12 h in vitro . Differential scanning calorimetry and X-ray diffraction studies showed that drug incorporated in the outer shell of the polymer was completely amorphous. Scanning electron micrographs indicated that the microsphere is perfect sphere with an internal hollow cavity enclosed by a rigid shell of polymer. The micromeritic properties of microspheres were found to be much improved compared with original drug crystals. The in vitro drug release behavior of the floating microspheres was characterized as an enteric property. Polymer being soluble above pH 7.0, the drug release rates from microspheres changed dramatically above and below pH 7.0. At intestinal pH the drug release was faster and continuous as compared to the amount released at gastric pH.

  7. Fiber-optic array using molecularly imprinted microspheres for antibiotic analysisElectronic supplementary information (ESI) available: Details of: (1) synthesis of BODIFLOXACIN, (2) purification of BODIFLOXACIN by semi-preparative HPLC and spectroscopic characterization, (3) chromatographic conditions for the separation of fluoroquinolones and other antibiotics, (4) binding of BODIFLOXACIN and ENRO to the encoded polymer microspheres and, (5) image acquisition and data analysis. Also included: Scheme 1, Tables S1 and S2, Fig. S1-S5. See DOI: 10.1039/c5sc00115c

    National Research Council Canada - National Science Library

    Carrasco, Sergio; Benito-Peña, Elena; Walt, David R; Moreno-Bondi, María C

    2015-01-01

    In this article we describe a new class of high-density optical microarrays based on molecularly imprinted microsphere sensors that directly incorporate specific recognition capabilities to detect enrofloxacin (ENRO...

  8. Coacervate microspheres as carriers of recombinant adenoviruses.

    Science.gov (United States)

    Kalyanasundaram, S; Feinstein, S; Nicholson, J P; Leong, K W; Garver, R I

    1999-01-01

    The therapeutic utility of recombinant adenoviruses (rAds) is limited in part by difficulties in directing the viruses to specific sites and by the requirement for bolus administration, both of which limit the efficiency of target tissue infection. As a first step toward overcoming these limitations, rAds were encapsulated in coacervate microspheres comprised of gelatin and alginate followed by stabilization with calcium ions. Ultrastructural evaluation showed that the microspheres formed in this manner were 0.8-10 microM in diameter, with viruses evenly distributed. The microspheres achieved a sustained release of adenovirus with a nominal loss of bioactivity. The pattern of release and the total amount of virus released was modified by changes in microsphere formulation. Administration of the adenovirus-containing microspheres to human tumor nodules engrafted in mice showed that the viral transgene was transferred to the tumor cells. It is concluded that coacervate microspheres can be used to encapsulate bioactive rAd and release it in a time-dependent manner.

  9. Demonstration of Microsphere Insulation in Cryogenic Vessels

    Science.gov (United States)

    Baumgartner, R. G.; Myers, E. A.; Fesmire, J. E.; Morris, D. L.; Sokalski, E. R.

    2006-04-01

    While microspheres have been recognized as a legitimate insulation material for decades, actual use in full-scale cryogenic storage tanks has not been demonstrated until now. The performance and life-cycle-cost advantages previously predicted have now been proven. Most bulk cryogenic storage tanks are insulated with either multilayer insulation (MLI) or perlite. Microsphere insulation, consisting of hollow glass bubbles, combines in a single material the desirable properties that other insulations only have individually. The material has high crush strength, low density, is noncombustible, and performs well in soft vacuum. These properties were proven during recent field testing of two 22,700-L (6,000-gallon) liquid nitrogen tanks, one insulated with microsphere insulation and the other with perlite. Normal evaporation rates (NER) for both tanks were monitored with precision test equipment and insulation levels within the tanks were observed through view ports as an indication of insulation compaction. Specific industrial applications were evaluated based on the test results and beneficial properties of microsphere insulation. Over-the-road trailers previously insulated with perlite will benefit not only from the reduced heat leak, but also the reduced mass of microsphere insulation. Economic assessments for microsphere-insulated cryogenic vessels including life-cycle cost are also presented.

  10. POE/PLGA composite microspheres: formation and in vitro behavior of double walled microspheres.

    Science.gov (United States)

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

    2003-03-07

    The poly(ortho ester) (POE) and poly(D,L-lactide-co-glycolide) 50:50 (PLGA) composite microspheres were fabricated by a water-in-oil-in-water (w/o/w) double emulsion process. The morphology of the composite microspheres varied depending on POE content. When the POE content was 50, 60 or 70% in weight, the double walled microspheres with a dense core of POE and a porous shell of PLGA were formed. The formation of the double walled POE/PLGA microspheres was analysed. Their in vitro degradation behavior was characterized by scanning electron microscopy, gel permeation chromatography, Fourier-transform infrared microscopy and nuclear magnetic resonance spectroscopy (NMR). It was found that compared to the neat POE or PLGA microspheres, distinct degradation mechanism was achieved in the double walled POE/PLGA microspheres system. The degradation of the POE core was accelerated due to the acidic microenvironment produced by the hydrolysis of the outer PLGA layer. The formation of hollow microspheres became pronounced after the first week in vitro. 1H NMR spectra showed that the POE core was completely degraded after 4 weeks. On the other hand, the outer PLGA layer experienced slightly retarded degradation after the POE core disappeared. PLGA in the double walled microspheres kept more than 32% of its initial molecular weight over a period of 7 weeks.

  11. PLGA/alginate composite microspheres for hydrophilic protein delivery

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Peng [Department of Anatomy and Cell Biology, University of Saskatchewan, S7N5E5 (Canada); Division of Biomedical Engineering, University of Saskatchewan, S7N5A9 (Canada); Chen, X.B. [Department of Mechanical Engineering, University of Saskatchewan, S7N5A9 (Canada); Division of Biomedical Engineering, University of Saskatchewan, S7N5A9 (Canada); Schreyer, David J., E-mail: david.schreyer@usask.ca [Department of Anatomy and Cell Biology, University of Saskatchewan, S7N5E5 (Canada); Division of Biomedical Engineering, University of Saskatchewan, S7N5A9 (Canada)

    2015-11-01

    Poly(lactic-co-glycolic acid) (PLGA) microspheres and PLGA/alginate composite microspheres were prepared by a novel double emulsion and solvent evaporation technique and loaded with bovine serum albumin (BSA) or rabbit anti-laminin antibody protein. The addition of alginate and the use of a surfactant during microsphere preparation increased the encapsulation efficiency and reduced the initial burst release of hydrophilic BSA. Confocal laser scanning microcopy (CLSM) of BSA-loaded PLGA/alginate composite microspheres showed that PLGA, alginate, and BSA were distributed throughout the depths of microspheres; no core/shell structure was observed. Scanning electron microscopy revealed that PLGA microspheres erode and degrade more quickly than PLGA/alginate composite microspheres. When loaded with anti-laminin antibody, the function of released antibody was well preserved in both PLGA and PLGA/alginate composite microspheres. The biocompatibility of PLGA and PLGA/alginate microspheres were examined using four types of cultured cell lines, representing different tissue types. Cell survival was variably affected by the inclusion of alginate in composite microspheres, possibly due to the sensitivity of different cell types to excess calcium that may be released from the calcium cross-linked alginate. - Highlights: • A double emulsion technique is used to prepare protein-loaded PLGA or PLGA/alginate microspheres. • PLGA, alginate and protein are distributed evenly within microsphere structure. • Addition of alginate improves loading efficiency and slows degradation and protein release. • PLGA/alginate microspheres have favorable biocompatibility.

  12. Selection of quasi-monodisperse super-micron aerosol particles

    Science.gov (United States)

    Rösch, Michael; Pfeifer, Sascha; Wiedensohler, Alfred; Stratmann, Frank

    2014-05-01

    Size-segregated quasi monodisperse particles are essential for e.g. fundamental research concerning cloud microphysical processes. Commonly a DMA (Differential Mobility Analyzer) is used to produce quasi-monodisperse submicron particles. Thereto first, polydisperse aerosol particles are bipolarly charged by a neutralizer, and then selected according to their electrical mobility with the DMA [Knutson et al. 1975]. Selecting a certain electrical mobility with a DMA results in a particle size distribution, which contains singly charged particles as well as undesired multiply charged larger particles. Often these larger particles need to either be removed from the generated aerosol or their signals have to be corrected for in the data inversion and interpretation process. This problem becomes even more serious when considering super-micron particles. Here we will present two different techniques for generating quasi-monodisperse super-micron aerosol particles with no or only an insignificant number of larger sized particles being present. First, we use a combination of a cyclone with adjustable aerodynamic cut-off diameter and our custom-built Maxi-DMA [Raddatz et al. 2013]. The cyclone removes particles larger than the desired ones prior to mobility selection with the DMA. This results in a reduction of the number of multiply charged particles of up to 99.8%. Second, we utilize a new combination of cyclone and PCVI (Pumped Counterflow Virtual Impactor), which is based on purely inertial separation and avoids particle charging. The PCVI instrument was previously described by Boulter et al. (2006) and Kulkarni et al. (2011). With our two setups we are able to produce quasi-monodisperse aerosol particles in the diameter range from 0.5 to 4.4 µm without a significant number of larger undesired particles being present. Acknowledgements: This work was done within the framework of the DFG funded Ice Nucleation research UnIT (INUIT, FOR 1525) under WE 4722/1-1. References

  13. Monodisperse Clusters in Charged Attractive Colloids: Linear Renormalization of Repulsion.

    Science.gov (United States)

    Růžička, Štěpán; Allen, Michael P

    2015-08-11

    Experiments done on polydisperse particles of cadmium selenide have recently shown that the particles form spherical isolated clusters with low polydispersity of cluster size. The computer simulation model of Xia et al. ( Nat. Nanotechnol. 2011 , 6 , 580 ) explaining this behavior used a short-range van der Waals attraction combined with a variable long-range screened electrostatic repulsion, depending linearly on the volume of the clusters. In this work, we term this dependence "linear renormalization" of the repulsive term, and we use advanced Monte Carlo simulations to investigate the kinetically slowed down phase separation in a similar but simpler model. We show that amorphous drops do not dissolve and crystallinity evolves very slowly under linear renormalization, and we confirm that low polydispersity of cluster size can also be achieved using this model. The results indicate that the linear renormalization generally leads to monodisperse clusters.

  14. Solvent: A Key in Digestive Ripening for Monodisperse Au Nanoparticles

    Science.gov (United States)

    Wang, Peng; Qi, Xuan; Zhang, Xuemin; Wang, Tieqiang; Li, Yunong; Zhang, Kai; Zhao, Shuang; Zhou, Jun; Fu, Yu

    2017-01-01

    This work has mainly investigated the influence of the solvent on the nanoparticles distribution in digestive ripening. The experiments suggested that the solvents played a key role in digestive ripening of Au nanoparticles (Au NPs). For the benzol solvents, the resulting size distribution of Au NPs was inversely related to the solvent polarity. It may be interpreted by the low Gibbs free energy of nanoparticles in the high polarity medium, which was supposedly in favor of reducing the nanoparticles distribution. Through digestive ripening in the highly polar benzol solvent of p-chlorotoluene, monodisperse Au NPs with relative standard deviation (RSD) of 4.8% were achieved. This indicated that digestive ripening was an effective and practical way to prepare high-quality nanoparticles, which holds great promise for the nanoscience and nanotechnology.

  15. Structure and Hydration of Highly Branched, Monodisperse Phytoglycogen Nanoparticles

    Science.gov (United States)

    Atkinson, John; Nickels, Jonathan; Stanley, Christopher; Diallo, Souleymane; Katsaras, John; Dutcher, John

    Monodisperse phytoglycogen nanoparticles are a promising, new soft colloidal nanomaterial with many applications in the personal care, food, nutraceutical and pharmaceutical industries. These applications rely on exceptional properties that emerge from the highly branched structure of phytoglycogen and its interaction with water, such as extraordinarily high water retention, and low viscosity and exceptional stability in water. The structure and hydration of the nanoparticles was characterized using small angle neutron scattering (SANS) and quasielastic neutron scattering (QENS). SANS allowed us to determine the size of the nanoparticles, evaluate their radial density profile, quantify the particle-to-particle spacing, and determine their water content. The results show clearly that the nanoparticles are highly hydrated, with each nanoparticle containing 250% of its mass in water, and that aqueous dispersions approach a jamming transition at ~ 25% (w/w). QENS experiments provided an independent and consistent measure of the high level of hydration of the particles.

  16. Electrospray formation of gelled nano-aluminum microspheres with superior reactivity.

    Science.gov (United States)

    Wang, Haiyang; Jian, Guoqiang; Yan, Shi; DeLisio, Jeffery B; Huang, Chuan; Zachariah, Michael R

    2013-08-14

    Nanometallic fuels with high combustion enthalpy, such as aluminum, have been proposed as a potential fuel replacement for conventional metallic fuel to improve propellant performance in a variety of propulsive systems. Nevertheless, nanometallic fuels suffer from the processing challenges in polymer formulations such as increased viscosity and large agglomeration, which hinder their implementation. In this letter, we employ electrospray as a means to create a gel within a droplet, via a rapid, solvent evaporation-induced aggregation of aluminum nanoparticles, containing a small mass fraction of an energetic binder. The gelled aluminum microspheres were characterized and tested for their burning behavior by rapid wire heating ignition experiments. The gelled aluminum microspheres show enhanced combustion behavior compared to nanoaluminum, which possibly benefits from the nitrocellulose coating and the gelled microstructure, and is far superior to the corresponding dense micrometer-sized aluminum.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-02-25

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

  18. Hierarchical bismuth phosphate microspheres with high photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Pei, Lizhai; Wei, Tian; Lin, Nan; Yu, Haiyun [Anhui University of Technology, Ma' anshan (China). Key Laboratory of Materials Science and Processing of Anhui Province

    2016-05-15

    Hierarchical bismuth phosphate microspheres have been prepared by a simple hydrothermal process with polyvinyl pyrrolidone. Scanning electron microscopy observations show that the hierarchical bismuth phosphate microspheres consist of nanosheets with a thickness of about 30 nm. The diameter of the microspheres is about 1 - 3 μm. X-ray diffraction analysis shows that the microspheres are comprised of triclinic Bi{sub 23}P{sub 4}O{sub 44.5} phase. The formation of the hierarchical microspheres depends on polyvinyl pyrrolidone concentration, hydrothermal temperature and reaction time. Gentian violet acts as the pollutant model for investigating the photocatalytic activity of the hierarchical bismuth phosphate microspheres under ultraviolet-visible light irradiation. Irradiation time, dosage of the hierarchical microspheres and initial gentian violet concentration on the photocatalytic efficiency are also discussed. The hierarchical bismuth phosphate microspheres show good photocatalytic performance for gentian violet removal in aqueous solution.

  19. The quest for targeted delivery in colon cancer: mucoadhesive valdecoxib microspheres

    Directory of Open Access Journals (Sweden)

    Thakral NK

    2011-05-01

    Full Text Available Naveen K Thakral1, Alok R Ray1,2, Daniel Bar-Shalom3, André Huss Eriksson4, Dipak K Majumdar51Centre for Biomedical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India; 2Biomedical Engineering Unit, All India Institute of Medical Science, New Delhi, India; 3Department of Pharmaceutics and Analytical Chemistry, 4Bioneer:FARMA, Department of Pharmaceutics and Analytical Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Copenhagen, Denmark; 5De