Colorimetric and Fluorescent Dual-Mode Measurement of Blood Glucose by Organic Silicon Nanodots

Organic silicon nanodots (OSiNDs) with ∼100% photoluminescence quantum yield (QY) were facilely prepared by a one-pot hydrothermal strategy and were particularly explored as a fluorescence indicator for biosensing in this work. Under the catalysis of glucose oxidase (GOx), hydrogen peroxide (H2O2) was produced during the oxidation of glucose. The consecutive oxidation of p-phenylenediamine (PPD) by H2O2 and horseradish peroxidase (HRP) led to the production of PPDox (2,5-diamino-N,N′-di-(4-aminophenyl)-2,5-cyclohexadiene-1,4-diimine). Based on the chromogenic nature of PPDox and the inner filter effect (IFE) of PPDox on the OSiNDs, a dual-mode colorimetric and fluorescent assay for ultrasensitive detection of glucose in serum was established. The limit of detection (LOD) of the present assay is 0.36 and 0.06 μM for the colorimetric mode and the fluorescent mode, respectively. Good consistency of testing results obtained from the present assay and a commercial glucometer demonstrated good reliability and application potential of the present assay for clinical diagnosis. By extending the applications of both fluorescent OSiNDs and the routine chromogenic reagent PPD, the ultrasensitive fluorescent approach of the present assay provided an effective tool for future screening of biological substances involved in H2O2-generation reactions.