A colorimetric assay for detection of glucose by enzymatic etching of triangular gold nanosheets

Abstract

Blood glucose detection is an essential of diabetes management, so it is urgent to develop a convenient and practical blood glucose monitoring method. Herein, a colorimetric assay for detection of glucose based on enzymatic etching of triangular gold nanosheets was reported. In the presence of glucose oxidase (GOD) catalyzed the oxidation of glucose to produce hydrogen peroxide (H2O2), which induced the etching of triangular gold nanosheets (AuTNPs) from the corner, leading to the blue shift in absorption peak. Both enzymatic reaction and H2O2 etching can lead to the localized surface plasmon resonance (LSPR) displacement. In this paper, the theoretical simulation, DLS measurement, TEM test and UV–vis absorption spectra experiment are combined to verify that the detection mechanism is etching, and it is verified that the etching starts from the corners of the triangle and gradually reaches the surface. At the same time, the sensor has a wide detection range. In addition, the ratio and concentration of EDC/NHS, pH value of phosphate buffered solution (PBS), GOD concentration and reaction temperature were studied, and the best detection conditions of glucose were determined. Under the optimal detection conditions, this glucose colorimetric sensor exhibits excellent sensing performance in the glucose range of 0.2–12 mM and the limit of detection is limit 0.1 mM (S/N = 3). In addition, glucose was tested in artificial fluids. The results demonstrated that the colorimetric analysis based on triangular gold nanosheets-glucose oxidase system performs in artificial fluids as well as in phosphate buffer solution, making it very suitable for the clinical diagnosis of diabetes.