壳聚糖涂覆磁性纳米颗粒对纤维素酶的固定化

设计具有高稳定性、选择性的酶-载体复合物是固定化酶领域的研究重点。本研究以环氧氯丙烷作为表面活性剂，通过沉淀法制备磁性纳米颗粒并涂覆壳聚糖，用以固定化纤维素酶。通过SEM扫描电镜、VSM磁强计、FTIR红外光谱对 Fe₃O₄-壳聚糖磁性纳米颗粒进行表征，并研究其固定化纤维酶的表征及酶学性质。结果表明，制备的磁性纳米颗粒晶形完整，纤维素酶有效固定在Fe₃O₄-壳聚糖载体表面；固定化纤维素酶比游离纤维素酶具有更好的酸碱稳定性和热稳定性。固定化纤维素酶在pH 2~9范围内均有较好的活性，并且置于60和70 ℃条件下4 h后，仍然能保持将近50％的活性，经10次循环利用后，固定化纤维素酶仍然保持在52.6%的活性，说明Fe₃O₄-壳聚糖可作为固定纤维素酶的有效载体，为固定化酶的进一步应用提供了参考。

Immobilization of Cellulase by Chitosan-Coated Magnetic Nanoparticles

The design of enzyme-carrier complexes with high stability and selectivity is the focus of research in the field of immobilized enzymes. In this study, magnetic nanoparticles were prepared by precipitation using epichlorohydrin as surfactant and coated with chitosan to immobilize cellulase. Scanning electron microscope (SEM), vibrating sample magnetometer (VSM) and Fourier transform infrared spectrometer (FTIR infrared spectroscopy) were used to characterize Fe₃O₄ chitosan magnetic nanoparticles, and the characterization and enzymatic properties of immobilized cellulase were studied. Results showed that the prepared magnetic nanoparticles were crystallographically intact and the cellulase was effectively immobilized on the Fe₃O₄-chitosan carrier surface. In addition, immobilised cellulase had better acid-base stability and thermal stability than free cellulase. It had good activity in the range of pH2~9, and also with better thermostability, remained nearly 50% activity for 4 h at 60 and 70 ℃. After 10 cycles of recycling, the immobilized cellulase remained at a high activity of 52.6%, indicating that Fe₃O₄-chitosan could be used as an effective carrier for immobilized cellulase, providing a reference for further applications of the immobilized enzyme.