Preparation And Characterization Of Nano-porous Material Lotus Fiber / Alginate

Natural polymer materials could be used in the field of tissue engineering and other medicine domain. To study the effect of its own factors on the degradation process and mechanism and design degradation of controllable of biological materials were the key issue to be solved. In this paper, we studied preparation and characterization of porous materials by sodium alginate and lotus nanofibers, and their degradation performance were discussed.(1) Preparation and characterization of spongy alginate porous materials. According to physicochemical characterization, sodium alginate was easy to processing molding. Alginate (Mw=3.0×105) was conducive to forming membranes. So, suitable molecular weight should be selected in order to improve their performance. With freeze-drying technology and pre-freezing at-10℃, we have builded the honeycomb materials (Porousity=92.06%). Changing the pre-freezing temperature can regulate pore structure to some extent. With the increased dosage of sodium alginate, the porosity and the pore size of the materials were reduced, while tensile strength and elongation at break increased. Water absorption performance of the materials was good. The above studies lay a foundation for construction of controllable degradation alginate porous materials.(2) The preparation of oxidized sodium alginate and controllable degradation study of alginate porous materials. Sodium alginate was aldehyde-modified and characterization of its chemical structure, the degree of oxidation and biodegradation. Then, oxidized sodium alginate was crosslinked respectively with calcium chloride and carboxymethyl chitosan, with their degradation performance studied.It was found that the non-oxidized alginate porous materials degrade slowly. The degradation rates of oxidized alginate were faster, which was up to61.71%. Thus, degradation rates of calcium chloride crosslinked porous materials increased while pH values of liquid decreased, which was proportional to the degree of oxidation. The oxidized alginate materials crosslinked with carboxymethyl chitosan degraded faster than non-oxidized one, with degradation rates decreased82.12%-100.00%during14days. Increasing dosage of carboxymethyl chitosan, the pH values tended to rise, which indicated that adjusting component mole ratio may control the material degradation rates and pH values.(3) Preparation of lotus nanofibers/alginate porous materials and controlled degradation studies. First, lotus fibers were carboxyl-modified with TEMPO/NaClO/NaBr system and got lotus nanofibers whose diameter reached15run. The carboxyl content of lotus nanofibers increased with the increase of oxidation time. Unmodified cellulose degradation rates were very slow. But degradation rates of lotus nanofibers were positively correlated with the carboxyl content and pH values were opposite.The degradation rates of the lotus nanofibers/alginate materials crosslinked with calcium chloride were slow (40.20%). In contrast, the materials crosslinked with carboxymethyl chitosan owned better performance such as porosity (87.10%), water absorption ration (1813.33%), mechanical properties (0.36MPa/7.73%) and in vitro degradation (59.16%). So, the materials crosslinked with carboxymethyl chitosan are expected to be used in medical fields such as skin tissue engineering.