海藻酸钠磁性微粒的制备及对漆酶的固定化

Preparation of Surface Modified Alginate Nanoparticles with Acyl Chloride Groups and Its Use in Immobilization of Laccase

利用化学共沉淀法制备纳米级磁性Fe3O4粒子,通过乳化作用把该粒子与海藻酸钠结合制备了磁性海藻酸钠微粒,将该磁性微粒进行表面修饰生成酰氯基团,并通过化学共价法固定漆酶。用正交实验优化了固定化条件,在此条件下获得了固定化漆酶;与游离漆酶相比,固定化漆酶与底物ABTS亲和力降低,最适pH值、最适温度相同,热稳定性显著提高,具有良好的循环使用性和贮藏稳定性,对染料刚果红的降解率也较高。结果表明,表面改性的海藻酸钠磁性微粒是一种良好的固定化漆酶载体。

Nanometer magnetic Fe3O4 particles were prepared by co-precipitation method. And with emulsification, the magnetic alginate nanopaticles were synthesized by taking Fe3O4 particles as nucleus, alginate as carrier. Then the magnetic particles were surface-modified with acyl chloride groups to immobilize lacease covalently. The conditions of immobilization of laccase were optimized by orthogonal design ： 100 U/mL laccase 5 mL, and immobilizing for 30 min. Compared with the free enzyme, the affinity to substrate ABTS of immobilized enzyme decreased, but its stability was considerably improved. The optimal pH and temperature for immobilized enzyme was 3 and 50℃ respective- ly. The activity of immobilized enzyme could remain 80% at a temperature of 70℃ for 7 h, but the free enzyme would be greatly affected under the same conditions ; the immobilized enzyme still remained about 50% of its initial activity after 10 cycles ; and the storage stability of laccase was greatly improved after its immobilization. The decolorization of immobilized and free laccase to dye Congo red after 12 h was 39. 92% and 22. 59% respectively. The result showed that the modified magnetic alginate nanoparticles were good carrier for laccase immobilization.