Homogeneous synthesis of linoleic acid-grafted chitosan oligosaccharide in ionic liquid and its self-assembly performance in aqueous solution

Abstract

A water-soluble amphiphilic derivative of chitosan oligosaccharide (COS) modified with linoleic acid (LA)-grafted COS (LCOS) has been synthesized in the ionic liquid 1-butyl-3-methylimidazolium acetate ([BMIM]Ac). The effects of the ionic liquid on the degree of substitution (DS), surface activity, and self-assembly behavior of LCOS have been investigated. The results showed that the ionic liquid homogeneous system led to a relatively higher DS compared with the product synthesized in a traditional organic solvent. Furthermore, the LCOS synthesized in the ionic liquid had better surface activity (cmc=1.1 × 10-4 g·mL-1), and could also self-assemble into nanomicelles with better-defined spherical shape and a narrower particle size distribution (30-40 nm) in aqueous solution. These results suggest that an effective and environmentally friendly synthesis method for COS derivatives has been established and, moreover, the obtained LCOS micelles meet the basic requirements for use as an improved drug transduction vector.