吡虫啉/羧甲基壳聚糖凝胶球的制备及释放性能

以羧甲基壳聚糖为载体材料,吡虫啉为模型药物,采用双组分交联剂的悬浮交联法制备了吡虫啉/羧甲基壳聚糖凝胶球,采用扫描电镜和红外光谱对凝胶球进行了表征,探讨了制备工艺条件对凝胶球性能影响,利用体外释放实验测定了交联羧甲基壳聚糖凝胶球的释放特性。研究表明,采用氯化钙-戊二醛双组分交联剂可获得外形规整而表面带有皱褶的载药凝胶球;交联凝胶球中吡虫啉与羧甲基壳聚糖间无化学键合;交联凝胶球的载药量和包封率随交联时间和氯化钙浓度的增加呈先升后降趋势,随戊二醛体积分数的增加呈显著下降趋势;吡虫啉释放速度,随交联剂中氯化钙浓度和戊二醛体积分数的增加呈先降后增趋势;随交联时间变化不显著。在较佳条件下可制备载药量为25.71%的吡虫啉/羧甲基壳聚糖凝胶球,控释时间可达6 d;释放机理初步确定为Super CaseⅡ型传递机理。

Preparation and Controlled Release of Imidacloprid/Carboxymethyl-chitosan Gel Beads

Carboxymethylchitosan was used as a carrier to formulate gel beads of imidacloprid with a mixture of glutaraldehyde and calcium chloride as double-component cross-linking agent.The gel beads were characterized by FTIR and SEM.The release profiles of imidacloprid from the beads were investigated in vitro.The formulation conditions were investigated and related to the properties of the beads.SEM data indicated that the imidacloprid-loaded beads had spherical shape with rough surface.The absence of chemical interactions between imidacloprid and carboxymethylchitosan in the beads was confirmed by FTIR.The loading of imidacloprid and the encapsulation enfficiency increased and then followed by a decrease with increasing cross-linking time and concentration of CaCl_2,but considerably decreased with increasing concentration of glutaraldehyde.The release rate of imidacloprid was reduced at first and then raised with increasing concentrations of glutaraldehyde and CaCl_2,but was not considerably influenced by the cross-linking time.Under optimum formulation conditions,imidacloprid-loaded gel beads were obtained with imidacloprid content of 25.71% and controlled release time up to 6.0 days.The release mechanism operated in the imidacloprid /carboxymethyl chitosan gel beads was Super Case Ⅱ transport.