Search Results (5)

Silicon (Si) is an essential trace element in the human body and it exists in connective tissue as aqueous orthosilicic acid. Porous chitosan–3-glycidoxypropyltrimethoxysilane (GPTMS) hybrids can regenerate nerve tissue and recover sensor and motor functions. However, the structures and roles of the degradation products with Si extracted from the hybrids in nerve regeneration are not clear. In this study, we prepared porous chitosan–GPTMS hybrids with different amounts of GPTMS to amino groups of chitosan (chitosan:GPTMS = 1:0.5 and 1:1 molar ratios). The structures of the degradation products with Si from the hybrids were examined using time-of-flight mass spectrometry, and biological assessments were conducted in order to evaluate their potential use in the preparation of devices for nerve repair. Glial and motor cell lines and ex vivo explants of dorsal root ganglia were used in this study for evaluating their behavior in the presence of the different degradation products with Si. The structure of the degradation products with Si depended on the starting composition. The results showed that glial cell proliferation was lower in the medium with the higher-molecular-weight degradation products with Si. Moreover, motor cell line differentiation and the neurite outgrowth of dorsal root ganglion explants were improved with the lower-molecular-weight degradation products with Si. The results obtained could be useful for designing a new nerve regeneration scaffold including silicon components. Full article

Chitosan is a cationic polymer that forms polymerized membranes upon reaction with anionic polymers. Chitosan−carboxymethyl cellulose (CMC) capsules are drug delivery carrier candidates whose mechanical strength and permeability must be controlled to achieve sustained release. In this study, the capsules were prepared from chitosan−γ-glycidoxypropyltrimethoxysilane (GPTMS)−CMC. The mechanical stability of the capsules was improved by crosslinking the chitosan with GPTMS. The capsules were then coated with hydroxyapatite (HAp) by alternately soaking them in calcium chloride solution and disodium hydrogen phosphate solution to prevent rapid initial drug release. Cytochrome C (CC), as a model drug, was introduced into the capsules via two routes, impregnation and injection, and then the CC released from the capsules was examined. HAp was found to be deposited on the internal and external surfaces of the capsules. The amount of CC introduced, and the release rate were reduced by the HAp coating. The injection method was found to result in the greatest CC loading. Full article

Microporous spheres in a hybrid system consisting of chitosan and γ-glycidoxypropyltrimethoxysilane (GPTMS) have advantages in a range of applications, e.g., as vehicles for cell transplantation and soft tissue defect filling materials, because of their excellent cytocompatibility with various cells. In this study, microporous chitosan-GPTMS spheres were prepared by dropping chitosan-GPTMS precursor sols, with or without a cerium chloride, into liquid nitrogen using a syringe pump. The droplets were then freeze dried to give the pores of size 10 to 50 μm. The cell culture tests showed that L929 fibroblast-like cells migrated into the micropores larger than 50 μm in diameter, whereas MG63 osteoblast-like cells proliferated well and covered the granule surfaces. The spheres with cerium chloride showed antibacterial properties against both gram-negative and gram-positive bacteria. Full article

The presence of several organic contaminants in the environment and aquatic compartments has been a matter of great concern in the recent years. To tackle this problem, new sustainable and cost-effective technologies are needed. Herein we describe magnetic biosorbents prepared from trimethyl chitosan (TMC), which is a quaternary chitosan scarcely studied for environmental applications. Core@shell particles comprising a core of magnetite (Fe₃O₄) coated with TMC/siloxane hybrid shells (Fe₃O₄@SiO₂/SiTMC) were successfully prepared using a simple one-step coating procedure. Adsorption tests were conducted to investigate the potential of the coated particles for the magnetically assisted removal of the antibiotic sulfamethoxazole (SMX) from aqueous solutions. It was found that TMC-based particles provide higher SMX adsorption capacity than the counterparts prepared using pristine chitosan. Therefore, the type of chemical modification introduced in the chitosan type precursors used in the surface coatings has a dominant effect on the sorption efficiency of the respective final magnetic nanosorbents. Full article

Burr holes in craniotomy are not self-repairing bone defects. To regenerate new bone at the sites of these defects, a good scaffold is required. Biodegradable hybrids including silica or siloxane networks have been investigated as bone tissue scaffolds. This study examined skull bone regeneration using chitosan-siloxane hybrids after long-term implantation (two and three years). After implantation of the hybrids, the surrounding cells migrated and formed fibrous tissues and blood vessels. Then, bone formation occurred from the surrounding blood vessels. Addition of calcium ions and coating with hydroxyapatite improved bone regeneration. Finally, the regenerated tissue area became smaller than the initial hole, and some areas changed to completed bone tissues. Full article