The Study of Methylene Blue Loading into Chitosan-graft-Maleic Sponges

Abstract

This work succeeded in synthesizing sponges from chitosan-graft-maleic anhydride. Chitosan and maleic anhydride at a certain mass ratio (1:2, 1:1; and 2:1) were reacted in dimethyl sulfoxide (DMSO) at 60℃ for 24 hours. While the gel formation was carried out in distilled water using a dialysis tube. The removal of DMSO from the gel was carried out by soaking the gel in distilled water for two days. After that, the obtained gel was frozen at -25℃ overnight before being lyophilized under a vacuum at -40℃ for 24 hours. The dry sponge weight obtained after lyophilization is about 5.61% – 6.77% (dry sponge/wet gel). FTIR and TG/DTA then characterized the sponges. The intensity of the new strong FTIR band appeared in the chitosan-graft-maleic sponge at 1560.13 cm-1, which corresponds to the C=C strain. The results of TG/DTA showed that pure chitosan and sponge chitosan-maleate underwent two stages of degradation, namely evaporation of water and pyrolysis of organic compounds. The shift in the peak rate of degradation in the second stage occurred at 300℃ for pure chitosan and at 340℃ for a graft-chitosan-maleate sponge. Both results indicate that the reaction was successful. The drug loading capability was investigated using methylene blue as the drug model. The drug loading kinetics corresponded to a pseudo-first-order model with kf ranging from 0.287 to 0.317 day-1. According to the Freundlich model, the adsorption equilibrium with Kf and 1/n values was 4.923 mg/gram and 2.192, respectively.