The Preparation Of Acylated Chitosan And Self-assembled Nanovesicles For Drug Delivery

Chitosan is a well-known biomaterial for its good biocompatibility, biodegradability and drug-absorption enhancement. Its unique chemical and biological properties make it an attractive biomaterial for a variety of pharmaceutical applications. Chitosan modification with long hydrophoblic acylated pendants is an important amphiphilic material, which has potential application in drug delivery system and tissue engineering. In this paper the studies on the synthesis of acylated chitosan and the preparation of chitosan-based self-assembled nanovesicles for drug delivery have been carried out.The experimental results indicate that the average substitution degree of acylation of chitosan depends on volume ratio of pyridine to chloroform in the reaction medium, chain length of the acyl chloride, and molecular weight of the chitosan. The products of full acylated chitosan, N-diacyl chitosan and O-diacyl chitosan were characterized by elemental analysis, FTIR and 1 H NMR. XRD measurements were made to investigate the crystallinity change caused by the acylation of chitosan. DSC-TG measurements were made to study their thermo behaviour as well.The self-assembled nanovesicles have first been prepared by using O-dilauroyl and O-dipalmitoyl chitosan in the study. The experiments have been done to study the drug-encapsulation ration, the drug-carried amount of vesicle material, and the drug release behavior of various vesicles with Vitamine B12 as model drug. The experimental results indicate that O-diacylatedl chitosan self-assembled vesicles show two order of drug release bahaviour according to the Fick's Formula.