Chitosan/glycerophosphate thermosensitive hydrogel crosslinked physically was a potential drug delivery carrier;however, long gelation time limits its application. Here, chitosan-amino acid (AA) thermosensitive hydrogels were prepared from chitosan (CS), αβ-glycerophosphate (GP), and L-lysine (Lys) or L-glutamic acid (Glu). The prepared CS-Lys/GP and CS-Glu/GP hydrogel showed good thermosensitivity and could form gels in a short time. The optimal parameters of CS-Lys/GP hydrogel were that the concentration of CS-Lys was 2.5%, the ratio of CS/Lys was 3.5/1.0, the ratio of CS-Lys/GP was 4.5/1.0. The optimal parameters of CS-Glu/GP hydrogel were that the concentration of CS-Glu was 3.0%, the ratio of CS/Glu was 2.0/1.0, and the ratio of CS-Glu/GP was 4.0/1.5. Chitosan-amino acid (CS-AA) thermosensitive hydrogel had a three-dimensional network structure. The addition of model drug tinidazole (TNZ) had no obvious effect on the structure of hydrogel. The results of infrared spectroscopy showed that there were hydrogen bonds between amino acids and chitosan. In vitro release results showed that CS-Lys/GP and CS-Glu/GP thermosensitive hydrogels had sustained release effects. Thus, the chitosan-amino acid thermosensitive hydrogels hold great potential as a sustained release drug delivery system.
Jianan TongHuiyun ZhouJingjing ZhouYawei ChenJing ShiJieke ZhangXinyu LiangTianyuan Du
Novel ethyl cellulose/chitosan microspheres （ECCMs） were prepared by the method of w/o/w emulsion and solvent evaporation. The microspheres were spherical, adhesive, and aggregated loosely with a size not bigger than 5 pm. The drug loading efficiency of berberine hydrochloride （BH） loaded in microspheres were affected by chitosan （CS） concentration, EC concentration and the volume ratio of V（CS）/V（EC）. ECCMs prepared had sustained release efficiency on BH which was changed with different preparation parameters. In addition, the pH value of release media had obvious effect on the release character of ECCMs. The release rate of BH from sample B was only a little more than 30% in diluted hydrochloric acid （dHCl） and that was almost 90% in PBS during 24 h. Furthermore, the drug release data were fitted to different kinetic models to analyze the release kinetics and the mechanism from the microspheres. The released results of BH indicated that ECCMs exhibited non-Fickian diffusion mechanism in dHCI and diffusion-controlled drug release based on Fickian diffusion in PBS. So the ECCMs might be an ideal sustained release system especially in dHCl and the drug release was governed by both diffusion of the drug and dissolution of the polymeric network.
Hui-Yun ZHOU Pei-Pei CAO Jie ZHAO Zhi-Ying WANG Jun-Bo LI Fa-Liang ZHANG
