Smartphone based platform for ratiometric fluorometric and colorimetric determination H2O2 and glucose

In this work, a new strategy for ratiometric fluorescent and colorimetric determination of H2O2 and glucose is proposed. The sensing system involves catalytic oxidation reaction of glucose oxidase (GOx) with glucose to generate H2O2. Under the catalysis of Fe2+, the 580 nm emission of carbon dots (C-dots) upon 365 nm excitation is reduced by H2O2, while the fluorescence emission at 450 nm of thiochrome (oxVB1) enhances with the oxidation reaction between H2O2/Fe2+system and VB1 (thiamine). Simultaneously, the color of the carbon dots (C-dots) suspension changes from purplish-red to colorless. Thus, the fluorescence intensity ratio (I450/I580) and the absorbance (A557) can be used to quantitatively determine H2O2 and glucose. Furthermore, we integrated fluorometric and colorimetric output with a smartphone platform to conduct on-site analysis of glucose without the need of spectrometer. A smartphone application (APP) was designed to take pictures and analyze R, G, B values of fluorometric and colorimetric signals, which delivered excellent analytical result for glucose. This ratiometric fluorescent and colorimetric sensing system on a smartphone platform ensures sensitive and convenient determination of glucose and H2O2, hence having great prospects in biomedical analysis.