Interfacial engineering of carbon dots with benzenediboronic acid for fluorescent biosensing

Glucose assay is highly important in clinical diagnostics of diabetes. Herein, we engineered the surface of carbon dots by complexation with functional ligand and constructed fluorescent biosensors for the detection of hydrogen peroxide and glucose. In this study, benzenediboronic acid is conjugated to the surface of citric acid-derived carbon dots through formation of boronate complexes with the nanoparticles. The oxidation of benzenediboronic acid with hydrogen peroxide effectively quenches fluorescence of carbon dots through electron transfer process. The sensing performance of the system according to different engineered surfaces of carbon dots was studied by using carbon dots derived from various precursors and different benzenediboronic acid analogues. As a simple mix-and-detect strategy, this system is facilely applied for glucose sensing as hydrogen peroxide is the product catalyzed by glucose oxidase. The benzenediboronic acid-conjugated carbon dots derived from citric acid act as excellent optical probes for sensitive analysis of glucose with detection limit of 0.4 μM. This sensing system shows great selectivity toward interferent species such as analogues of glucose, and can be used to determine glucose in human serum. Engineering the surface of carbon dots by complexation with ligand of interest provides a feasible way to facilitate the development of biological applications.