Optical Detection of Thiol Drugs by Core–Shell Luminous Carbon Dots—Gold Nanoparticles System

nowadays, carbon quantum dots (cqds) with size less than 10 nm have emerged as one of the most exciting areas of chemical research in the class of inorganic nanomaterials. this article presents interesting characteristics of cqds and their fluorescence turn-on/turn-off quenching for the detection of 6-thioguanine (6-tg). the cqds were fabricated by a simple one-step microwave technique and used for the simultaneous reduction of au3+ to form au0-cqd core–shell (au@cqd) nanocomposites. the cqds formed were spherical in shape having an average size of ~ 7 nm confirmed by high-resolution transmission electron microscopy (hrtem) and dls study. the interaction of cqds with au leads to its fluorescence turn-off up to 96% analyzed by uv-visible, fluorescence spectroscopy, and fluorescence lifetime measurements. the turn-on fluorescence of cqds has been witnessed by the formation of complex with 6-tg [au-(6-tg)n]3− in the presence of thiols. meanwhile, linear relationship between turn-on fluorescence against the concentration of 6-tg is obtained in the range of 0–100 μm with the correlation coefficient of 0.9944 and limit of detection for 6-tg has been found to be 0.01 μm. the au@cqds could also act as biosensor for the detection of various amino acids, enzymes, and pentids drug.