Green emissive nitrogen-doped graphene quantum dots for fluorescence off–on probing methimazole via palladium (II) mediated assay

Abstract

A palladium ion ([Formula: see text])-mediated nitrogen-doped graphene quantum dots (N-GQDs/Pd[Formula: see text]) was developed as a fluorescent “off–on” probe for methimazole (MZ). Fluorescent N-GQDs interact with Pd[Formula: see text] through coordination interactions, leading to weak photoluminescence (PL) owing to the quenching ability of Pd[Formula: see text]. Upon introducing MZ, the stronger binding between N-GQDs and Pd[Formula: see text] destroys the N-GQDs/Pd[Formula: see text] complex and restores the PL of N-GQDs. The probe exhibits a linear PL response to MZ concentrations from 3.0 to 50.0 [Formula: see text]M with a detection limit down to 4.5 nM. In addition, the probe has been used to detect MZ in real samples including natural water sources and human urine.