Integration of mimic multienzyme systems in metal-metalloporphyrin gel composites for colorimetric sensing

In this paper, a hierarchically porous metal - metalloporphyrin gel (MMPG) based mimic multienzyme system for colorimetric sensing is reported. The synthesis conditions for gel state Fe-MMPG were systematically investigated and the porous structures were readily controlled by varying the reactant concentrations. Based on Fe-MMPG-5 with appropriate mesopores, glucose oxidase encapsulated in Fe-MMPG-5 (GOx@Fe-MMPG-5) with high loading capacity was achieved. The Fe-MMPG-5 provides not only mesopores for enzyme immobilization but also peroxidase-mimic activity in the GOx@Fe-MMPG-5 composite. This multienzyme system was further used for cascade catalysis and colorimetric sensing of glucose with low limit of detection, excellent selectivity and reusability. In additional, this system could also be applied to other oxidases, such as cholesterol oxidase, with intriguing properties. This study combines the advantages of porous gel materials and natural enzymes, providing potential to construct superior biocatalysts for advanced applications in biosensors, industrial catalysis, analytical equipment, and biofuel cells.