Bimetallic nanozyme mediated urine glucose monitoring through discriminant analysis of colorimetric signal

The ability to detect glucose concentrations in human urine offers a non-invasive approach to monitor changes in blood glucose, kidney health and vascular complications associated with diabetes. We show the potential of employing catalytically active nanoparticles directly grown on textiles to produce a dose-dependent colorimetric sensor for glucose. We use a galvanic replacement (GR) reaction for the synthesis of bimetallic nanoparticles. Here, Cu nanoparticles act as a sacrificial template that undergoes a spontaneous electroless GR reaction when exposed to metal ions of gold, silver, platinum, and palladium to form bimetallic Cu-M nanoparticles (M = Au, Ag, Pt, or Pd). The evaluation of their intrinsic peroxidase-mimicking catalytic activity ("nanozyme") in comparison to that of the Cu nanozyme revealed that the bimetallic systems show a higher catalytic rate with the Cu-Pt nanozyme showing the highest catalytic efficiency. This property of the Cu-Pt nanozyme was then utilized to detect glucose in human urine using the glucose oxidase enzyme as a molecular recognition element. A key outcome of our study is the ability to detect urine glucose without requiring sample dilution which is an advantage over the gold standard GOx-POx method and significantly more reliable performance over commercial urine glucose dipsticks. The difference in the intensity of the colorimetric response between different glucose concentrations further allowed this sensor system to be combined with digital imaging tools for multivariate analysis.