A self-activated nanobiocatalytic cascade system based on an enzyme-inorganic hybrid nanoflower for colorimetric and visual detection of glucose in human serum

A new enzyme-inorganic hybrid nanoflower was synthesized and used to achieve a self-activated cascade reaction for glucose detection, and a visual analytical device for screening of the diabetes was also developed. The glucose oxidase-ferrous phosphate hybrid nanoflowers (GOx-Fe-3(PO4)(2)center dot 8H(2)O HNFs) with two types of morphologies were obtained, in which the nanostructures with hydrangea-like morphology were selected for the subsequent study owing to their excellent catalytic activity. The HNFs exhibited significantly enhanced catalytic activity, stability and reusability compared with free enzymes. In virtue of their good catalytic properties, the HNFs realized the self-activated cascade detection of glucose by integrating two different types of enzymes. First, GOx catalyzed glucose to produce H2O2 and gluconic acid. Then, the generated gluconic acid decreased pH of the reaction system to about 4 which was the optimum pH for Fe-3(PO4)(2)center dot 8H(2)O to arouse its peroxidase-like activity. The in-situ formed H2O2 was finally catalyzed by adjacent Fe-3(PO4)(2)center dot 8H(2)O to oxidize 3,3', 5,5'-tetramethylbenzidine (TMB), resulting in a significant color change. This proposed assay has been successfully achieved the glucose detection in human serum with good accuracy and reproducibility. Moreover, a new visual analytical device for screening of the diabetes was developed, which offered a new strategy for the field analysis of glucose.