Abstract: A novel hydrogel system (HD) composed of soybean (SB) protein and chitosan(CS) blended with naturally non-toxic genipin was developed for controlling theophylline delivery. Additionally, the release profile of a model drug (theophylline) from test hydrogels was investigated in simulated gastric and intestinal fluid as well as pH7.4 buffer. The surface morphology and structure of composite chitosan-based hydrogels were characterized by infrared spectrophotometry and scanning electron microscopy as well as ¹H NMR spectra. These results showed obvious crosslinking systems for soybean protein and chitosan by genipin in the composite hydrogels. These composite hydrogels had retained compact sheets. All hydrogels swelled in the simulated gastric and intestinal solution as well as pH7.4 buffer, but the swelling ratio of the hydrogels in the simulated gastric medium was low. In addition, the amount of theophylline released in the simulated gastric medium (pH1.2) was lower than that in intestinal fluid (pH6.8) and pH7.4 buffer. These composite hydrogels were found to be pH-sensitive. The controlled release of theophylline was realized in 120 h. Therefore, the genipin-corsslinked composite hydrogel could be a suitable carrier for site-specific drug delivery in the intestine.

Key words: genipin, soybean protein, chitosan, composite hydrogel, controlled-release, site-specific drug delivery

摘要： 利用天然无毒的京尼平交联大豆蛋白(SB)和壳聚糖(CS)制备复合水凝胶(HD)并用作茶碱的控释载体。同时对其在模拟胃肠液和pH7.4缓冲液（PBS）中的控释特性进行了研究。结合扫描电镜和红外光谱以及核磁共振表征了复合凝胶的表观形态和结构。结果表明，复合水凝胶中大豆蛋白和壳聚糖通过京尼平发生了明显的交联作用，并呈现致密的片层结构。复合凝胶在模拟胃肠液和pH7.4PBS中均呈现溶胀现象，在模拟胃液中的溶胀度较低。而且凝胶在pH1.2模拟胃液中的释放量比模拟肠液和pH7.4PBS液中的低，并发现该凝胶具有pH响应，在120 h内可实现对茶碱的可控释放。因此，这种京尼平交联的复合凝胶具有作为药物在胃肠道中定向运送载体的潜力。

关键词: 京尼平, 大豆蛋白, 壳聚糖, 复合凝胶, 可控释放, 定向运送载体