Low-molecular-weight chitosans derived from β-chitin: preparation, molecular characteristics and aggregation activity

Abstract

Preparation, molecular characteristics, and aggregation activity of low-molecular-weight chitosans derived from β-chitin have been studied in comparison with those of chitosans from α-chitin. Chitosan derived from β-chitin was partially degraded with alkali and acid to prepare chitosans with reduced molecular weights. The reaction was also conducted with chitosan from α-chitin, but it was less susceptible to the degradation than chitosan from β-chitin. The resulting two series of chitosans had molecular weights ranging from 11 to 436 kDa. GPC analysis showed similar changes in the molecular weight distribution in the progress of main chain cleavage of the two kinds of chitosans. The polydispersity values were 2.01–4.16, indicating relatively narrow molecular weight distributions. These chitosans aggregated bovine serum albumin efficiently, and the aggregation behavior was dependent on the molecular weight and concentration of chitosan in addition to the pH of the media and concentration of sodium chloride. The aggregation activity of chitosans from β-chitin was found to be somewhat higher than that of chitosans from α-chitin.