Clinically colorimetric diagnostics of blood glucose levels based on vanadium oxide quantum dots enzyme mimics

Abstract

The environmental vulnerability of the natural enzyme have always been the most concerned issue in the diagnosis of blood glucose levels, which could be settled by the discovery and application of nanozyme mimics. However, the nanozyme still encountered with the problem of complex preparation process or low enzymatic activities. Herein, peroxidase-like vanadium oxide quantum dots (VOxQDs) were synthesized via a one-step bottom-up solvothermal method using vanadium (Ⅲ) trichloride (VCl3) powder as the precursor. Besides, the most favorable temperature and solvent for VOxQDs synthesis were confirmed. Due to the inherent properties of quantum dots, including larger specific surface areas and more active sites, the as-prepared VOxQDs exhibited 43 times lower value of Km and 32 times higher one of Vmax than those of natural peroxidase using H2O2 as the substrate, indicating the higher affinity and stronger peroxidase-like activity of the VOxQDs nanozymes. Accordingly, a facile and sensitive colorimetric sensor to detect glucose was designed via the integrated enzyme system of VOxQDs and glucose oxidase, which showed wider linear range of 0.005 - 2 mM glucose and lower limit of detection of 1.7 μM compared with those of many other peroxidase-like nanozymes. Especially, the colorimetric sensor was demonstrated with reliable and satisfactory performance in detection of glucose in human serum, which was in good accordance with the clinical results provided from the domestic hospital.