本文采用离子交联和巯基化两种不同方式改性壳聚糖，制备载有活性蛋白的壳聚糖水凝胶。通过红外光谱、粒径/zeta电位分析、透射电镜、扫描电镜、模拟消化实验等手段，探讨了其微观结构和控释性能。实验结果发现，由于分子间氢键作用，pH值、CS:TPP质量比以及BSA浓度等对交联壳聚糖水凝胶的蛋白包载率影响明显，而由于巯基的引入，使得巯基化壳聚糖水凝胶在酸性环境下具有较小的粒径（平均409.61 nm）和较低的表面电势（平均-0.67 mV）。壳聚糖基材料微观结构的变化进而影响其水凝胶的控释性能。模拟消化实验显示，交联壳聚糖水凝胶在模拟胃液中出现突释现象，在运送至结肠前，已有44.76%的活性蛋白释放，而巯基化壳聚糖水凝胶在模拟上消化道环境中释放缓慢，仅有8.42%的活性蛋白释放，运转至模拟结肠，活性蛋白释放速度逐渐增加，呈现持续释放的效果，约有34.53%的BSA逐渐释放在结肠中。因此，巯基化壳聚糖基水凝胶具有更好的控释性能，这对活性蛋白的生物利用改善具有重要作用。

In this paper, two different methods of ion cross-linking and sulfhydrylization were used to modify chitosan to prepare chitosan hydrogel with active protein. Through infrared spectroscopy, particle size/zeta potential analysis, transmission electron microscopy, scanning electron microscopy, and simulated digestion experiments, the microstructure and controlled release performance were discussed. The experimental results found that due to intermolecular hydrogen bonding, pH value, CS:TPP mass ratio, and BSA concentration had significant effects on the protein loading rate of cross-linked chitosan hydrogels, and the introduction of sulfhydryl groups made the sulfhydryl chitosan polymerized. Sugar hydrogel had a smaller particle size (average 409.61 nm) and a lower surface potential (average -0.67 mV) in an acidic environment. The changes in the microstructure of chitosan-based materials further affected the controlled release properties of their hydrogels. The simulated digestion experiment showed that the cross-linked chitosan hydrogel had a sudden release phenomenon in the simulated gastric juice. Before being transported to the colon, 44.76% of the active protein had been released, while the sulfhydryl chitosan hydrogel simulated the environment of the upper digestive tract. The medium release rate was slow, only 8.42% of the active protein was released. When it runs to the simulated colon, the release rate of the active protein gradually increases, showing a sustained release effect. About 30% of BSA is gradually released in the colon. Therefore, sulfhydryl chitosan-based hydrogels have better controlled release performance, which plays an important role in improving the bioavailability of active proteins.

国家自然科学基金资助项目（31601422）；广州市科技计划项目珠江新星专题（201806010184）