An investigation on the short-term biodegradability of chitosan with various molecular weights and degrees of deacetylation

At the present work, we have studied the short-term degradation of chitosan with different degrees of deacetylation (DID) and molecular weights. The various grades of chitosan were characterized throughout DD range, molecular weight, crystallinity and swelling ratio. The biodegradation of chitosan was examined by using simulated intestinal fluid (SIF, pH 7.5) at 37 degrees C and 150 rpm permanent shaking to mimic a typical physiological condition. The results revealed that in high DDs no significant changes in molecular weight and DD were observed. However, molecular weight loss percentage, DID changes percentage and swelling ratio increased with decreasing the initial DD and increasing the initial molecular weight. Scanning electron microscope (SEM) images showed no significant changes in particle size after degradation. These observations demonstrated that short-term degradation of chitosan has not occurred through the beta-chain scission and it can be related to the peptide bond cleavage of acetoamido side groups of the polymer. (C) 2009 Elsevier Ltd. All rights reserved.