Practical synthesis and characterization of mannose-modified chitosan

A new and practical laboratory approach to synthesize mannose modified chitosan (Man-chitosan) was developed via reductive amination reaction. Chitosan and mannose were used as raw materials. The reaction condition was mild and controllable. The overall yield was 47-52%. Each reaction products and Man-chitosan were characterized by 1H NMR, ESI-MS, FT-IR and TGA spectrum. FT-IR and 1H NMR results showed that mannose conjugated to chitosan via an alkane chain bridge (CH2CH2). The degree of substitution was calculated by element analysis. TGA results indicated that mannose grafted to chitosan slightly decreased the thermal stability of chitosan in some extent. MTT assay indicated that Man-chitosan was low cytotoxicity against HepG-2 and SMMC-7721 cells.