Gold nanoparticle-mediated fluorescence quenching of NCQDs for turn-on detection of glutathione

Abstract

In this study, we report a sensitive and selective fluorescence-based sensing platform for the detection of glutathione (GSH) using an energy transfer system composed of nitrogen-doped carbon quantum dots (NCQDs) and gold nanoparticles (AuNPs). The fluorescence emission of the NCQDs is initially quenched by AuNPs (0.014 to 1.13 nM) through mechanisms such as energy transfer. Upon the introduction of GSH (16.6 to 316 μM), the thiol groups exhibit a strong affinity toward the AuNPs surface, leading to nanoparticle aggregation, which in turn disrupts the quenching interaction and results in significant fluorescence recovery. This “turn-on” fluorescence response enables the quantification of GSH with high sensitivity and selectivity with linear regression coefficient (0.98), exhibiting a low detection limit (44.33 μM). The proposed system operates under mild conditions, requires no complex modification, and demonstrates excellent potential for real-time monitoring of GSH levels in biological samples. This work highlights the practical utility of NCQD–AuNPs nanohybrids in biomedical diagnostics and redox biology.