Study On The Preparation And Properies Of Chitosan Based Nanofibers Using Self-assembly Technique

In this study, natural polysaccharides-chitosan (CS) was used to prepare a kind of novel nanofibrous material with tripolyphosphate in adipic acid solution under mild conditions. The preparation was based on the electrostatic self-assembly between positive polyelectrolyte and negative polyelectrolyte.By means of TEM, SEM, FTIR, DSC, XRD, Raman spectrometer, the physicochemical characteristics of CS-based nanofibers and CS-based nanoparticles prepared by a similar method were characterized, and the formation mechanism of nanofibers and nanoparticles was discussed.We further investigated the effects of the concentration of chitosan solution, the ratio of cations to anions, pre-freezing temperature and pH value of aqueous media on the nanofibrous diameter, the structure in solid state and the stability of nanofibers. As the results showed, the diameter of nanofibers was increased with the increasing of CS concentration or the enhancing of the cations/ anions ratio, and the nanofibrous structures were kept well both in acetic environment and alkaline medium. Biomimetic nanofibers could be prepared on suitable CS concentration and ratio of cations to anions. Furthermore, we found that collagen-modified CS-based nanofibers could be obtained by electrostatic self-assembly too.The performances of nanofibers were very important in their applications. In this work, we cultured bonemarrow stromal cells and seeded them on nanofibers to evaluate the cellular compatibility, and the bioactivityof nanofibers was also determined by biomineralization experiment. Moreover, drug releasing property ofCS-based nanofibers was investigated by studying the release behavior of dexamethasone sodium phosphate(DMP, as a model of drug molecule) and bovine serum albumin(BSA, as a model of macromolecule).The results of BMSCs culture experiment told us that nanofibers had a good cellular compatibility, which could help to improve cellular adhesion as well as prolarizative ability and induced cells to excrete extra cellular matrix. Biomineralization experiment showed that CS-based nanofibers could induce Ca, P salts to form hydroxyapatite, which was proved have a wonderful bioactivity. Drug release research indicated the nanofibers were excellent carriers of model drugs, and they also played well in controlling the release behavior of such drugs. The release behavior of drugs loaded in CS-based nanofibers fitted well in polymer drug releasing model. Because of the good loading and releasing performance, the CS-based biomimetic nanofibers have a potential in tissue engineering.