可生物降解温度/pH双重感应型壳聚糖凝胶载体的制备和性能研究

Preparation and Properties of Biodegradable Chitosan Carriers with Thermo-/pHSensitive Controlled-Release Characteristics

制备了基于壳聚糖和多羟基盐类化合物的凝胶给药系统,研究了其柱状凝胶和球状凝胶的制备以及其温度和pH双重感应性。结果表明,该系统在低于室温时呈液态,升温至37℃左右则形成固态凝胶,并且凝胶温度越高,凝胶强度越好。发现制备的凝胶具有pH感应性,以VB12为模型药物,对柱状凝胶在不同pH环境下的释放特性进行了表征。在pH为4.0条件下,70 min内释放药物65%左右;pH为7.4下,相同时间内只释放了57%左右。以改性壳聚糖为原料的凝胶释药实验表明,在pH为4.0下,柱状凝胶70 min内释放了42%左右;pH为7.4下,相同时间内仅释放了37%左右,降低释放速率的同时在一定程度上保持了凝胶原有的温度和pH复合感应性。在不同pH环境下释药后和在生物降解前后的凝胶微观形貌有明显的差别。

Hydrogel drug delivery systems based on chitosan/polyol salt combinations were prepared with cylindrical and spherical shapes, and their thermo/pH-sensitivities were investigated. The systems could be held liquid below room temperature and they formed monolithic gels at body temperature. The higher the gelling temperature was, the higher the strength of hydrogels. VB12 was taken as the model drug and the release characteristics of the prepared system were studied at various pH environments. Under pH 4.0 condition, about 65 % of the drug was released within 70 min; while under pH 7.4 condition,about 57% released within the same time. Release experiments on hydrogels with modified chitosan were performed. Under pH 4.0 condition, the hydrogel system released 42% within 70 min;while under pH 7.4 condition, it only released 37 % within the same time. By modifying the chitesan, the rate of release was decreased while the thermo-/ pH-sensitivities were retained in a certain extent. Distinct differences of microstructures of hydrogels were found both after release experiments in different pH conditions and after biodegradation.