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Gel Fibers (gel + fiber)
Selected AbstractsPreparation and pH-sensitivity of polyacrylonitrile (PAN) based porous hollow gel fibersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Xinyuan Shen Abstract Polyacrylonitrile based porous hollow gel fibers were prepared from PAN hollow fibers by oxidation and subsequent alkaline treatment. Fourier-transform infrared (FTIR), X-ray diffraction, and scanning electron microscope (SEM) analyses showed that the PAN porous hollow gel fiber was a kind of amphoteric fiber due to the combination of cationic groups of pyridyl and anionic groups of carboxyl; after gelation the hollow channel and finger-like pores on the fiber walls were conserved. The effects of cyclization reaction degree, alkaline solution concentration, and alkaline treatment time on the mechanical properties or pH-sensitive behavior of the porous hollow gel fibers were investigated. The elongation/contraction behavior was studied in detail. It was found that the gel fiber exhibited a large swelling in an alkaline solution and contracting in an acid solution; the swelling change in length was above 90%; the responsive time of elongation/contraction was less than 20 s; the maximum contraction force was 20 N/cm2; and pH-sensitivity was reversible. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Decreasing effective nanofluidic filter size by modulating electrical double layers: Separation enhancement in microfabricated nanofluidic filtersELECTROPHORESIS, Issue 23 2008Hansen Bow Abstract Conventional methods for separating biomolecules are based on steric interactions between the biomolecules and randomly oriented gel fibers. The recently developed artificial molecular sieves also rely on steric interactions for separation. In this work, we present an experimental investigation of a method that can be used in these sieves to increase separation selectivity and resolution. This method exploits the electrostatic repulsion between the charged molecules and the charged nanofluidic structure. Although this method has been mentioned in the previous work, it has not been examined in detail. We characterize this method by comparing the selectivity with that achieved in devices with different dimensions. The results of this study are relevant to the optimization of chip-based gel-free biomolecule separation and analysis. [source] Coimmobilization of malic enzyme and alanine dehydrogenase on organic,inorganic hybrid gel fibers and the production of L -alanine from malic acid using the fibers with coenzyme regenerationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Koji Nakane Abstract Malic enzyme (EC 1.1.1.39) and alanine dehydrogenase (EC 1.4.1.1) were entrap-immobilized on hybrid gel fibers of cellulose acetate (CA) and zirconium (Zr) alkoxide by air-gap wet spinning. The production of L -alanine from malic acid with coenzyme regeneration was examined with the enzymes immobilized on the fibers. The productivity of L -alanine of the immobilized enzymes decreased to approximately one-fifth of that of free enzymes, but the CA,Zr-fiber-immobilized enzymes retained a high level of productivity after repeated use. Reduced form of nicotinamide adenine dinucleotide (NADH) recycling also occurred effectively for the enzymes immobilized on the fiber. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Preparation and pH-sensitivity of polyacrylonitrile (PAN) based porous hollow gel fibersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Xinyuan Shen Abstract Polyacrylonitrile based porous hollow gel fibers were prepared from PAN hollow fibers by oxidation and subsequent alkaline treatment. Fourier-transform infrared (FTIR), X-ray diffraction, and scanning electron microscope (SEM) analyses showed that the PAN porous hollow gel fiber was a kind of amphoteric fiber due to the combination of cationic groups of pyridyl and anionic groups of carboxyl; after gelation the hollow channel and finger-like pores on the fiber walls were conserved. The effects of cyclization reaction degree, alkaline solution concentration, and alkaline treatment time on the mechanical properties or pH-sensitive behavior of the porous hollow gel fibers were investigated. The elongation/contraction behavior was studied in detail. It was found that the gel fiber exhibited a large swelling in an alkaline solution and contracting in an acid solution; the swelling change in length was above 90%; the responsive time of elongation/contraction was less than 20 s; the maximum contraction force was 20 N/cm2; and pH-sensitivity was reversible. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Bioactivity, pre-osteoblastic cell responses, and osteoconductivity evaluations of the electrospun non-woven SiO2,CaO gel fabricsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2009Yang-Jo Seol Abstract The evaluations of the fibers characteristics, bioactivity, pre-osteoblastic cell responses, and osteoconductivity of the non-woven SiO2,CaO gel fabric made by electrospinning method was carried out. Silica gels with four different calcium contents were prepared by condensation following hydrolysis of tetraethyl orthosilicate under acidic conditions. The molar ratios of Ca to Si prepared ranged from 0 to 0.15. SiO2,CaO gel fabrics were heat-treated at 300°C for 3 h after spinning under an electric field of 2 kV/cm. As the Ca to Si ratio increased, the diameter of electrospun SiO2,CaO gel fibers increased because the viscosity of the SiO2,CaO gel solution increased. The apatite-forming ability of heat-treated, non-woven SiO2,CaO gel fabric was evaluated in simulated body fluid and tended to increase with an increasing Ca to Si molar ratio. However, proliferation and differentiation tended to decrease with an increasing Ca to Si molar ratio. The sample which had the Ca to Si ratio as 0.10 showed good osteoconductivity in vivo in the calvarial defect New Zealand white rabbit model compared to that had the Ca to Si ratio as 0 and empty defect. These results strongly suggest that non-woven SiO2,CaO gel fabric made by the electrospinning method has potential for application as a bone grafting material. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [source] Alkoxide Sol-Gel-Processed Cordierite FiberJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2002Mu-Tsun Tsai An alkoxide sol-gel route was developed to prepare stoichometric cordierite fibers. The influences of the aging treatment and heating rate on the sinterability of the gel fibers were also examined. X-ray diffraction analysis revealed that the unaged and aged fibrous gels all remained amorphous <800&, but began crystallization into ,-cordierite and ,-cordierite at ,900°C and 1050°C, respectively; single-phase ,-cordierite fibers were obtained at 1300°C. Heating the unaged fibers yielded denser microstructures, with fine grain sizes of ,0.2,0.4 ,m, whereas the aged fibers exhibited porous microstructures following heating at 1300°C. A higher heating rate and aging treatment resulted in a higher open porosity of the fired fiber. [source] Role of Capping Ligands on the Nanoparticles in the Modulation of Properties of a Hybrid Matrix of Nanoparticles in a 2D Film and in a Supramolecular OrganogelCHEMISTRY - A EUROPEAN JOURNAL, Issue 36 2009Asish Pal Dr. Abstract We incorporate various gold nanoparticles (AuNPs) capped with different ligands in two-dimensional films and three-dimensional aggregates derived from N -stearoyl- L -alanine and N -lauroyl- L -alanine, respectively. The assemblies of N -stearoyl- L -alanine afforded stable films at the air,water interface. More compact assemblies were formed upon incorporation of AuNPs in the air,water interface of N -stearoyl- L -alanine. We then examined the effects of incorporation of various AuNPs functionalized with different capping ligands in three-dimensional assemblies of N -lauroyl- L -alanine, a compound that formed a gel in hydrocarbons. The profound influence of nanoparticle incorporation into physical gels was evident from evaluation of various microscopic and bulk properties. The interaction of AuNPs with the gelator assembly was found to depend critically on the capping ligands protecting the Au surface of the gold nanoparticles. Transmission electron microscopy (TEM) showed a long-range directional assembly of certain AuNPs along the gel fibers. Scanning electron microscopy (SEM) images of the freeze-dried gels and nanocomposites indicate that the morphological transformation in the composite microstructures depends significantly on the capping agent of the nanoparticles. Differential scanning calorimetry (DSC) showed that gel formation from sol occurred at a lower temperature upon incorporation of AuNPs having capping ligands that were able to align and noncovalently interact with the gel fibers. Rheological studies indicate that the gel,nanoparticle composites exhibit significantly greater viscoelasticity compared to the native gel alone when the capping ligands are able to interact through interdigitation into the gelator assembly. Thus, it was possible to define a clear relationship between the materials and the molecular-level properties by means of manipulation of the information inscribed on the NP surface. [source] | ||||||||||