Facilely synthesised sulphur-doped carbon dots for highly selective determination of picric acid and for biological imaging

Abstract

ABSTRACT Here, yellow fluorescent sulphur-doped carbon dots (S-CDs) with high quantum yield (QY) of ~27.9% were synthesised from m-cresol purple by a fast and low-cost one-step hydrothermal method without other reagents. The surface morphology, functional groups and optical properties of S-CDs were characterised by high-resolution transmission electron microscope (HRTEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectrum and ultraviolet visible (UV-vis) absorption. The fluorescence intensity of S-CDs can be specifically and stably quenched by picric acid (PA) through inner filtration effect (IFE). The linearity between fluorescent intensity and PA concentration was used for developing a fluorescent probe with detecting range of 0–259.0 μM and a detection limit as low as 14.6 nM. We developed the method by applying S-CDs to determine PA in lake water with recoveries in the range of 93.0–103.7%, which verified the feasibility of this probe in practical analysis. In addition, due to the low toxicity and good biocompatibility, S-CDs can be applied to biological imaging.