光交联羟丙基壳聚糖纳米凝胶的制备及其释药性能

通过在水溶性的壳聚糖衍生物--羟丙基壳聚糖(HPCS)的氮基上引入具有光反应活性的叠氮基团(4-叠氮苯甲酸),制备了一种光可引发交联的叠氮化羟丙基壳聚糖(Az-HPCS).利用红外光谱、核磁共振及氨基滴定法对其结构和取代度进行了表征.通过离子交联和光交联两步交联法制备了壳聚糖纳米凝胶,用透射电镜观察了纳米凝胶的形貌和粒径,并研究了纳米凝胶在不同pH值溶液中的溶胀度、载药行为及释药性能.实验结果表明包封率与溶液pH值无关,而溶胀度及释药行为则主要受pH值的影响.在酸性条件(pH 2.60)下,溶胀度最大,突释现象也最明显,30 min内释药率可达8O%;在碱性条件(pH 9.40)下,溶胀度最低,药物释放速度较慢,2 h内释药率仅为40%;而在中性条件(pH 7.38)下,该纳米凝胶溶胀度中等,有明显的缓控释效果.

Preparation of Photocrosslinked Hydroxypropyl Chitosan Nanogel and Its Drug Releasing Properties

Photocrosslinkable chitosan (Az-HPCS) was prepared by introducing Az-group onto the amino group of a water-soluble chitosan derivative,hydroxylpropyl chitosan (HPCS).The chemical structure and substitution degree of Az-HPCS were FTIR,NMR and amino-group titration methods.Chitosan nanogel was then prepared by ionic-crosslinking followed by photocrosslinking.The morphology and size of the yield nanogel was then characterized by TEM.Furthermore,the swelling degree,entrapment efficiency and drug releasing hehavior were studied as well.It was found that the entrapment efficiencies of the nanogel at different pH were similar,while the swelling degree and releasing behavior were related to the pH of the enviroment.At pH 2.60,the nanogel has the highest swelling ratio (80%),and the loaded drug was burst released in the beginning 30 minutes.At pH 9.40,nanogel has the lowest swelling ratio,and only release 40% of the drug in 2 hours.However,in neutral condition (pH 7.38),the nanogel showed great controlled releasing property.