A coumarin ‐modified graphene quantum dot‐based luminogen for the detection of cysteine in aqueous media

3-aminocoumarin functionalized graphene quantum dot (AMC-GQD) as a turn-off fluorescent-based sensor for the selective and sensitive detection of cysteine in aqueous media via photoinduced hole transfer mechanism. AbstractA biocompatible fluorescence sensor for cysteine detection receives wide appreciation recently, because of its importance in the medical field. Functionalized graphene quantum dots (GQDs) are recently emerging biocompatible quantum dots, which are considered as suitable candidates for biomolecule detection. Motivated by this concept, here we have developed a versatile fluorescent probe based on 3-aminocoumarin (AMC) functionalized GQDs for the detection of cysteine (Cys). Modification on GQD with AMC resulted in a stable fluorescent probe with an enhancement in quantum yield of about 84% and 40  nm redshift in emission peak compared with bare GQD. The modified GQD is then used for the sensitive and selective detection of cysteine in aqueous media. The detection of Cys within the linear range of 50 nM to 1.5 μM was achieved with a detection limit (LOD) of 0.86 nM. Here, the AMC-GQD exhibit a turn-off fluorescence sensing behavior. The quenching mechanism was also explored. The sensing process follows dynamic quenching mechanism, which is attributed to the photoinduced charge transfer from AMC-GQD to Cys. The Stern–Volmer plot, energy-level alignment obtained from cyclic vol tammetry measurements and density functional theory predictions give a vali...

Source: Photochemistry and Photobiology - November 14, 2023 Category: Science Authors: Deepa Sebastian, Kala Ramakrishnan Tags: RESEARCH ARTICLE Source Type: research