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Composite Microspheres (composite + microsphere)
Selected AbstractsBioactive and Degradable Composite Microparticulates for the Tissue Cell Population and Osteogenic DevelopmentADVANCED ENGINEERING MATERIALS, Issue 10 2009Hye-Sun Yu Bioactive and degradable composite microspheres (bioactive glass,synthetic biopolymer) were produced to deliver tissue cells and to aid their osteogenic development targeted for hard tissues. Cellular population (left, SEM cell image at day 3) and osteoblastic differentiation (right, immunofluorescence staining with bone marker at day 14) on the microspheres was evident, suggesting the composite microspheres provided effective 3D substrate conditions for hard tissue regeneration. [source] Lyophilization to improve drug delivery for chitosan-calcium phosphate bone scaffold construct: A preliminary investigationJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2009Benjamin T. Reves Abstract Lyophilization was evaluated in chitosan-calcium phosphate microspheres and scaffolds to improve drug delivery of growth factors and antibiotics for orthopedic applications. The dual delivery of an antibiotic and a growth factor from a composite scaffold would be beneficial for treatment of complex fracture sites, such as comminuted fractures and segmental bone defects. The aim of this investigation was to increase the loading capacity of the composite by taking advantage of the increased porosity, due to lyophilization, and to produce an extended elution profile using a secondary chitosan-bead coating. The physiochemical properties of the composite were investigated, and loading and elution studies were performed with alkaline phosphatase (ALP), bone morphogenetic protein-2 (BMP-2), and amikacin. Lyophilization was found to increase the surface area of scaffolds by over 400% and the porosity of scaffolds by 50%. Using ALP as a model protein, the loading capacity was increased by lyophilization from 4.3 ± 2.5 to 24.6 ± 3.6 ,g ALP/mg microspheres, and the elution profile was extended by a supplemental chitosan coating. The loading capacity of BMP-2 for composite microspheres was increased from 74.4 ± 3.7 to 102.1 ± 8.0 ,g BMP-2/g microspheres with lyophilization compared with nonlyophilized microspheres. The elution profiles of BMP-2 and the antibiotic amikacin were not extended with the supplemental coating. Additional investigations are planned to improve these elution characteristics for growth factors and antibiotics. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [source] Stability of ,-galactosidase immobilized on composite microspheres of artemisia seed gum and chitosanPOLYMER COMPOSITES, Issue 1 2008Ji Zhang In this work, composite microspheres were prepared by using artemisia seed gum and chitosan as a source. The composite microspheres have activated aldehyde groups by using glutaraldehyde. ,-Galactosidase was covalently bound on these activated microspheres. The properties of the immobilized enzyme were investigated and compared with those of the free enzyme, for which o -nitrophenol ,- D -galactopyranoside (ONPG) was chosen as a substrate. The results showed that the pH and thermal stability of the immobilized ,-galactosidase were higher than those of the soluble one. Apart from these, the Michaelis constant Km was evaluated for the immobilized ,-galactosidase and the soluble enzyme. The immobilized ,-galactosidase exhibited better environmental adaptability and reusability than the soluble one. POLYM. COMPOS., 29:9,14, 2008. © 2007 Society of Plastics Engineers [source] Synthesis of Novel Porous Magnetic Silica Microspheres as Adsorbents for Isolation of Genomic DNABIOTECHNOLOGY PROGRESS, Issue 2 2006Zhichao Zhang 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 ,m, a surface area of 250 m2/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. [source] | ||||||||||