Janus DNA bridges metal-organic frameworks and graphene oxide for convenient and efficient multienzyme co-immobilization with boosted activity

Metal-organic frameworks (MOFs) are excellent platforms for enzyme immobilization. However, strong or weak interactions between enzymes and MOFs often lead to inactivation and enzyme leaching. Herein, single-stranded DNA (ssDNA) with Janus properties was used as a linker between enzymes and the dual carriers of MOFs and graphene oxide (GO), which provided a simple and effective platform to tightly co-immobilize glucose oxidase (GO X ) and horseradish peroxidase (HRP). Mechanistic investigation revealed that the enzyme was immobilized mainly through π-π stacking between nucleobases and GO and coordination of the sugar-phosphate backbone with zirconium clusters in MOFs. This strategy ameliorated traditional surface adsorption issues for enzyme immobilization on MOFs. By introducing GO and ssDNA, the GO X &HRP cascade reaction on MOFs was enhanced significantly, showing better kinetics than the corresponding free GO X &HRP. Furthermore, the immobilized GO X &HRP exhibited substrate selectivity and a wide linear range for glucose detection. This enzyme immobilization strategy should have broad application prospects and practical value in biocatalysis and diagnostics.