One-pot enzyme- and indicator-free colorimetric sensing of glucose based on MnO2 nano-oxidizer

To establish more stable and lower cost colorimetric methods for the sensing of glucose, the artificial nanozymes were developed as the substitutes of natural enzymes (glucose oxidase, GOx; peroxidase). However, the common utilized nanozymes cannot show both the tandem enzymatic activities and the color indicating performance at the same time, which lead to the further addition of natural enzyme or color indicator. To overcome these problems, we fabricate a novel one-pot enzyme- and indicator-free method for the colorimetric sensing of blood glucose levels based on the direct redox reaction of MnO2/glucose. The MnO2 nanomaterial is acted as an active nano-oxidizer, and a color nano-indicator for the sensing of blood glucose levels. In the presence of target glucose, the MnO2 nano-oxidizers is reduced to Mn2+, leading to the dramatic decreasing absorbance and fading color of yellow MnO2 solution. This nanosystem demonstrates wide liner range from 10 μM to 5 mM with low detectable limit of 10 μM. In addition, it shows favorable applicability for the glucose monitoring in human blood sample. Our proposed strategy takes advantage of the direct redox reaction of glucose and MnO2, which eliminates the use of natural enzymes (GOx, peroxidase) and the color indicator, and realized a sensitive, low-cost and convenient method for the colorimetric sensing of glucose.