Enzymes Immobilization Based On Metal-Organic Frameworks And Its Performance

Enzymes have excellent catalytic eficiency,specificity and selectivity.Howeve,the poor stability,low reusability and high cost of free enzymes restrict their practical application.Immobilization technology could improve the stability,activity and reusability of enzymes effectively,which is able to solve the problem above.Metal-Organic Frameworks(MOFs)have received considerable attention in enzyme immobilization because of their excellent properties,including high loading capacity,organic-solvent tolerance and thermal stability.Nevertheless,the external small-dimension mesopores and micropores of MOFs are inconsistent with large-sized enzymes,which limits enhancement of the mass transfer efficiency and catalytic properties of the enzyme.Multiple studies have demonstrated that the application of Hierarchically Porous Metal-Organic Frameworks(HP-MOFs)in immobilized enzymes can significantly enhance mass transfer efficiency.Furthermore,metalloporphyrin-based Fe-MOFs with peroxidase-like activity are expected to expand the application of immobilized enzymes in the fields of biocatalysis and biosensing.Therefore,the thesis constructed immobilized enzyme composite based on single-crystal ordered macropore zeolitic imidazolate framework-8(SOM-ZIF-8)with macro-and microporous structure,and PCN-222 with hierarchical porous structure and enzyme mimic activity by post-synthetic immobilization method,then determined their catalytic activity,stability and reusability,and further evaluated application potential of immobilized enzyme in pollutants biodegradation and biosensing.The main results obtained in this thesis are as follows.1.The methodology of this article relies on the strong shaping effects of a polystyrene nanosphere monolith template and a double-solvent induced heterogeneous nucleation approach to construct SOM-ZIF-8.SOM-ZEF-8 with highly ordered macropores and stable single crystal structure,has potential application in chemical adsorption/separation and bulky-molecule catalytic,which could immobilize HRP on SOM-ZIF-8 to construct HRP@SOM-ZIF-8 by post-synthetic immobilization method.The complex had high catalytic activity,high stability and excellent recyclability.Furthermore,the combination of superior adsorption performance of SOM-ZIF-8 and catalytic degradation performance of HRP,HRP@SOM-ZIF-8 can remove hazardous dyes quickly and effectively.2.Hierarchically Porous PCN-222(HP-PCN-222)with peroxidase-like activity was obtained by "A Modulator-Induced Defect-Formation Strategy",which could succeed immobilization of Glucose oxidase(GOx)to construct GOx@HP-PCN-222.HP-PCN-222 could not only immobilize enzyme but also contain peroxidase-like catalytic activity,thus catalyzing the cascade reactions cooperated with the immobilized GOx,which can achieve a highly sensitive determination of glucose with a linear range of 0.236-200 pM,and the limit of detection can be as low as 0.236?M.At the same time,after immobilization,glucose oxidase exhibits good catalytic activity,stability(pH,high temperature and storage)and excellent recyclability.