Abstract:

Chitosan-based composite materials were prepared using the inverse-phase suspension cross-linking technique by
protecting the amino group in chitosan through the Schiff base reaction. Amino-chitosan was obtained after modification of
the composite materials with ethidene diamine and its structure was characterized. In addition, the effect of epoxypropane
concentration on free amino groups on the surface of amino-chitosan was investigated; the amount of free amino groups was
measured using potassium polyvinylsulfate (PVSK). Also, the effects of porogen, pre-cross-linking agent and cross-linking
agent on the entrapment efficiency of anthocyanin were evaluated as well as sustained release properties of anthocyaninloaded
amino-chitosan. The results showed that the amount of free amino group was reduced with increasing epoxypropane
concentration. With increasing concentrations of porogen, pre-cross-linking agent and cross-linking agent within certain
ranges, the entrapment efficiency of anthocyanin was also gradually increased, but decreased when they exceeded the ranges.
Under simulated human physiological conditions, the release of anthocyanin from chitosan particles at pH 1.72 and 37 ℃
was (81.63 ± 1.92)% in 4 h, and complete release was achieved in 10 h. By contrast, the release of anthocyanin at pH 8.25
and 37 ℃ was (71.68±2.55)% in 4 h, and the entrapped anthocyanin was almost completely released in 10 h. The release
curves, observed to follow normal distribution patterns, showed that the chemically modified chitosan can be used for
sustained release of anthocyanin.

Key words: anthocyanin, sustained release, amino-chitosan, preparation