Colorimetric Agarose Gel Sensors Based on Cu-Doped Carbon Nanowires

The colorimetric sensor has made great achievements in glucose sensing and diabetes prediction due to its simplicity, visualization, and lack of need for sophisticated instruments. The noninvasive sampling method has received more attention. Herein, a colorimetric agarose gel sensor was constructed by combining Cu-doped carbon nanowires (CuCNWs) with excellent peroxidase-like activity and glucose oxidase (GOx). CuCNWs can effectively catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) with a maximum catalytic rate of 12.5 × 10–8 M s–1, which is superior to most nanomaterials reported. The modification by PVP can significantly improve the stability of CuCNWs under physiological conditions without affecting their catalytic activity. By introducing GOx, the sensitive detections of hydrogen peroxide (H2O2) and glucose in a wide range with the limit of detection as low as 30 nM and 0.2 μM can be achieved. Notably, the colorimetric agarose gel sensor exhibits a higher sensitivity than commercial test strips in detecting glucose in solution. Furthermore, it was applied to the detection of urine glucose. Diabetic urine can be easily distinguished from normal urine by judging color changes with the naked eye. This work is of great significance in guiding the construction of colorimetric agarose gel sensors and expands the applications of nanozymes in the biosensing fields.