Abstract:

Enzyme immobilization expands the practical application of the enzymes since it overcomes the drawbacks of free enzymes, such as easy deactivation, poor stability and difficulty in recovery. In recent years, as an emerging type of carriers for enzyme immobilization, metal-organic frameworks (MOFs) materials have been gaining considerable attentions in academic fields due to their large specific surface area, high porosity, adjustable pore size, open metal sites, various structures, and compositions. This review summarized the recent advances in immobilized enzymes on MOFs, with emphasis on the preparation strategies of de novo synthesis and post-synthesis, and the involved immobilization mechanisms (including carrier encapsulation, surface adsorption, covalent bonding, and pore diffusion). The advantages and limitations of different methods were discussed as well. For example, de novo synthesis allows the pore size of MOFs less than target enzymes，but requires MOFs which could be prepared in mild conditions; post-synthesis allows the synthesis of MOFs to occur in harsh conditions but has relatively complex process. In addition, the practical applications of enzyme-MOFs composites in the environmental field for contaminant detection and removal were summarized. Finally, it is pointed out that the further application of MOFs immobilized enzymes in environmental fields should be based on thorough fundamental research in terms of the synergistic effect of enzymes and MOFs on decontamination of pollutants, the rational design and controllable synthesis strategies.

Key words: enzyme, immobilization, metal-organic frameworks, immobilization strategy, environmental application

摘要：

固定化酶克服了游离酶易失活、稳定性差、难以回收利用的缺点，扩大了酶的实际应用范围。近年来，由于金属有机框架（metal-organic frameworks，MOFs）独特的性质，如比表面积大、孔隙率高、孔径可调节、开放的金属位点和多样的结构组成等，其作为固定化酶的新型载体成为研究热点。本文综述了近年来MOFs固定化酶的研究进展，其中重点讨论了酶在MOFs上的固定化方法（从头合成和后合成）和机理（载体包埋、表面吸附、共价连接和孔道扩散），并且分析了不同合成方法的优势和局限性，如从头合成可以选择孔径小于目标酶尺寸的MOFs，但要求MOFs的合成条件温和；后合成可以选择合成条件苛刻的MOFs，但固定化过程相对复杂。此外，还对MOFs固定化酶在环境污染物检测和去除方面的应用进展进行了总结。最后对MOFs固定化酶在环境领域的应用研究和面临的挑战进行了展望，提出应关注MOFs固定化酶中MOFs和酶对污染物的协同作用以及MOFs固定化酶的可控制备。

关键词: 酶, 固定化, 金属有机框架, 固定化方法, 环境应用