Bienzyme co-immobilized on Zr-Based MOF with hierarchical porous structure for visual detection of glucose

Metal-organic frameworks (MOFs) are considered as promising carriers for immobilized enzymes. Whereas, some interrelated and restrictive problems exist in the construction of MOFs immobilized enzymes with excellent catalytic performance, resulting in reduced catalytic activity of the enzymes. In this work, a novel hierarchical porous structure of Zr-based metal-organic frameworks (Zr-MOF, HPU) was accurately constructed for coimmobilizing horseradish peroxidase (HRP) and glucose oxidase (GOx). The prepared HPU carrier can enrich the substrate by using the abundant micropore structure around the mesopore, thus reducing the mass transfer resistance and making up for the loss of enzyme activity during enzyme immobilization. Notably, GOxHRP@HPU demonstrated outstanding catalytic efficiency and excellent stability, as well as ideal reusability, maintaining nearly 95% initial activity at 60 celcius after 1 h incubation and above 65% initial activity after 10 reuses. Both the immobilization process and interaction of substrates with co-immobilized bienzyme reactor were investigated by means of microcalorimetry, which demonstrated HPU was an excellent platform for coimmobilized HRP and GOx. Furthermore, GOx-HRP@HPU was used for the detection of glucose with excellent detection performance.