Preparation,characterization,and antibacterial activity of oleic acid-grafted chitosan oligosaccharide nanoparticles

An oleic acid-grafted chitosan oligosaccharide(CSO-OA)with different degrees of amino substitution(DSs)was synthesized by the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide(EDC)-mediated coupling reaction.Fourier transform infrared spectroscopy(FT-IR)suggested the formation of an amide linkage between amino groups of chitosan oligosaccharide and carboxyl groups of oleic acid.The critical aggregation concentrations(CACs)of CSO-OA with 6%,11%,and 21%DSs were 0.056,0.042,and 0.028 mg·mL^(-1),respectively.Nanoparticles prepared with the sonication method were characterized by means of transmission electron microscopy(TEM)and Zetasizer,and the antibacterial activity against Escherichia coli and Staphylococcus aureus was investigated.The results showed that the CSO-OA nanoparticles were in the range of 60-200 nm with satisfactory structural integrity.The particle size slightly decreased with the increase of DS of CSO-OA.The antibacterial trial showed that the nanoparticles had good antibacterial activity against E.coli and S.aureus.