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Successful Formation (successful + formation)
Selected AbstractsHierarchically Assembled Mesenchymal Stem Cell Spheroids Using Biomimicking Nanofilaments and Microstructured Scaffolds for Vascularized Adipose Tissue EngineeringADVANCED FUNCTIONAL MATERIALS, Issue 14 2010Taek Gyoung Kim Abstract Composite multicellular spheroids composed of mesenchymal stem cells (MSCs) and synthetic biodegradable nanofilaments are fabricated. Extracellular-matrix-mimicking nanofilaments, prepared from transverse fragmentation of semicrystalline poly(L -lactic acid) nanofibers and subsequent surface modification with cell adhesive peptides, are used to form composite multicellular spheroids with MSCs by cellular self-assembly. The size of the composite spheroids could be readily controlled with the integrated amount of the nanofilaments. The composite spheroids show enhanced adipogenic potential compared to homotypic spheroids. The resultant spheroids are used as building blocks for 3D biohybrid construction with the assistance of a microstructured scaffold fabricated by a direct polymer melt deposition process. An angiogenic growth factor, basic fibroblast growth factor, is also locally delivered in a sustained fashion from the heparinized scaffold surface for facile neovascularization of adipogenic tissue. The produced multiscaled and multifunctional hybrid MSC construct enable the successful formation of vascularized adipose tissue in vivo. [source] Air-liquid interface (ALI) culture of human bronchial epithelial cell monolayers as an in vitro model for airway drug transport studiesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2007Hongxia Lin Abstract Serially passaged normal human bronchial epithelial (NHBE) cell monolayers were established on Transwell® inserts via an air-liquid interface (ALI) culture method. NHBE cells were seeded on polyester Transwell® inserts, followed by an ALI culture from day 3, which resulted in peak TEER value of 766,±,154 ,,×,cm2 on the 8th day. Morphological characteristics were observed by light microscopy and SEM, while the formation of tight junctions was visualized by actin staining, and confirmed successful formation of a tight monolayer. The transepithelial permeability (Papp) of model drugs significantly increased with the increase of lipophilicity and showed a good linear relationship, which indicated that lipophilicity is an important factor in determining the Papp value. The expression of P-gp transporter in NHBE cell monolayers was confirmed by the significantly higher basolateral to apical permeability of rhodamine123 than that of reverse direction and RT-PCR of MDR1 mRNA. However, the symmetric transport of fexofenadine,·,HCl in this NHBE cell monolayers study seems to be due to the low expression of P-gp transporter and/or to its saturation with high concentration of fexofenadine,·,HCl. Thus, the development of tight junction and the expression of P-gp in the NHBE cell monolayers in this study imply that they could be a suitable in vitro model for evaluation of systemic drug absorption via airway delivery, and that they reflect in vivo condition better than P-gp over-expressed cell line models. ©2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96:341,350, 2007 [source] IPM/DOSS/water microemulsions as reactors for silver sulfadiazine nanocrystal synthesisJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2005Jerry Nesamony Abstract The first goal of this work was the preparation of a water-in-oil microemulsion from components generally regarded as safe for use in humans. Stable formulations without need of a co-surfactant were prepared from isopropyl myristate (IPM), dioctyl sodium sulfosuccinate (DOSS), and water. A ternary phase diagram was prepared for the IPM/DOSS/water system. The IPM/DOSS/water microemulsions were characterized by conductivity and dynamic laser light scattering (DLS). The results obtained from conductivity experiments indicate conductivity values of less than 1 ,S/cm and were consistent with the formation of w/o microemulsions. The DLS results showed that the emulsified water droplets had an average diameter range of 9.2 to 19.7 nm, depending on composition. Modulation of the droplet size is possible by varying the water to DOSS molar ratio and DOSS to IPM ratio. The second goal of this work was the preparation of silver sulfadiazine (AgSD) nanoparticles. It was hypothesized that two separate microemulsions containing dispersed aqueous droplets of either sodium sulfadiazine or silver nitrate would react when mixed. The DLS results are consistent with the successful formation of submicron AgSD crystals. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:1310,1320, 2005 [source] Micellar behavior of well-defined polystyrene-based block copolymers with triethoxysilyl reactive groups and their hydrolysis,condensationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2010Cé Guinto Gamys Abstract Block copolymers of acryloxy propyl triethoxysilane and styrene were prepared through nitroxide-mediated polymerization using alkoxyamine initiators based on N - tert -butyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide. The copolymers were characterized by 1H NMR, size exclusion chromatography and differential scanning calorimetry. Their micellar behavior in dioxane/methanol solutions was examined through static light scattering and transmission electron microscopy (TEM). TEM indicated the successful formation of spherical micelles which were subsequently frozen by the sol,gel process. Hydrolysis,condensation of the reactive ethoxysilyl side groups was followed by FTIR, 1H NMR, and 29Si NMR. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 784,793, 2010 [source] RAFT polymerization of styrenic-based phosphonium monomers and a new family of well-defined statistical and block polyampholytesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2007Ran Wang Abstract We describe herein the first example of the controlled reversible addition-fragmentation chain transfer (RAFT) radical homo- and copolymerization of phosphonium-based styrenic monomers mediated with a trithiocarbonate-based RAFT chain transfer agent (CTA) directly in aqueous media. In the case of homopolymer syntheses the polymerizations proceed in a controlled fashion yielding materials with predetermined molecular characteristics as evidenced from the narrow molecular mass distributions (MMD) and the excellent agreement between the theoretical and experimentally determined molecular masses (MM). We also demonstrate the controlled nature of the homopolymerization of 4-vinylbenzoic acid with the same CTA in DMSO. We subsequently prepared both statistical and block copolymers from the phosphonium/4-vinylbenzoic acid monomers to yield the first examples of polyampholytes in which the cationic functional group is a quaternary phosphonium species. We show that the kinetic characteristics of the statistical copolymerizations are different from the homopolymerizations and proceed, generally, at a significantly faster rate although there appears to be a composition dependence on the rate. Given the inherent problems in characterizing such polyampholytic copolymers via aqueous size exclusion chromatography we have qualitatively proved their successful formation via FTIR spectroscopy. Finally, in a preliminary experiment we qualitatively demonstrate the ability of such pH-responsive block copolymers to undergo supramolecular self-assembly. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2468,2483, 2007 [source] Double-Grafted Cylindrical Brushes: Synthesis and Characterization of Poly(lauryl methacrylate) BrushesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2007Youyong Xu Abstract Double-grafted cylindrical brushes with poly(lauryl methacrylate) (PLMA) as the side chains were synthesized using the grafting-from strategy via atom transfer radical polymerization (ATRP). The polyinitiator poly[2-(2-bromoisobutyryloxy)ethyl methacrylate] (PBIEM) with ,=,240 and 1,500 served as the backbone. The PLMA side chains of the brushes carry long alkyl chains. GPC and 1H NMR measurements confirmed the successful formation of the PLMA cylindrical brushes. The side chains were cleaved from the cylindrical brushes by transesterification. GPC and 1H NMR results indicate that the initiating efficiency of the bromoester groups on the backbone for the bulky monomer was in the range of 0.34,,,f,,,0.67. Static and dynamic light scattering show that the ratio of the radius of gyration to the hydrodynamic radius, Rg/Rh, is in the range of 1.2,1.3, indicating that the LMA cylindrical brushes are semiflexible in solution. Atomic force microscopy (AFM) measurements show that short PLMA brushes exhibit a spherical morphology while the long brushes exhibit a worm-like structure. DSC displayed melting peaks at around ,30,°C, indicating the alkyl side chains of the PLMA chains in the double-grafted cylindrical brushes are crystallizable. [source] | ||||||||||