Preparation and characterization of hydrogels based on dehydroabietyl polyoxyethylene glycidyl ether grafted hydroxyethyl chitosans and their capability for loading and controlled release of chloramphenicol

Dehydroabietol polyoxyethylene(10) ether (DHA(EO)10H) was reacted with epichlorohydrin (ECH) using BF3 as catalyst and transformed into DHA(EO)10H-ECH, then dehydrochlorinated in the presence of sodium hydroxide and converted into dehydroabietyl polyoxyethylene(10) glycidyl ether (DHA(EO)10GE). Hydroxyethyl chitosan (HEC) was modified with DHA(EO)10GE, and a series of different DHA(EO)10GE-grafted HECs (DHA(EO)10GE-g-HECs) were prepared. Finally, the hydrogels based on DHA(EO)10GE-g-HECs were obtained through the reaction between genipin (GE) and DHA(EO)10GE-g-HECs. Effects of the grafting degree (DG) of DHA(EO)10GE and the dosage of GE on the gelation ability of mixed solution composed of DHA(EO)10GE-g-HECs and GE were investigated, and the behaviors of DHA(EO)10GE-g-HEC/GE hydrogels as carriers for loading chloramphenicol (CAP) were studied. It was found that the gelling time of the DHA(EO)10GE-g-HEC with high DG was longer than that with low DG, and a higher GE dosage could improve the capability of DHA(EO)10GE-g-HEC to form hydrogels. The relation between the cumulative release rate of CAP, which was loaded in DHA(EO)10GE-g-HEC/GE gel, and the release times in artificial intestinal fluid could be well described by Boltzmann function. Increasing the DG or decreasing the GE dosage could improve the final cumulative release.