Synthesis of green fluorescent carbon dots using cysteine and maltose as ecofriendly ligands for the detection of venlafaxine anti-depression drug in pharmaceutical and plasma samples.

[Display omitted] • Green fluorescent CM-CDs were prepared using cysteine and maltose as precursors. • Green fluorescent CM-CDs showed λ Ex/Em at 420/511 nm. • CM-CDs acted as a sensor for sensing of venlafaxine via fluorescence "turn-off" mechanism. • This method exhibited wider linear range (0.1–180 µM) with a LOD of 75.15 nM for venlafaxine. • This method successfully applied to assay venlafaxine in biofluids and pharmaceutical samples. In this work, the green emissive carbon dots (CDs) were fabricated using cysteine and maltose as bio-precursors via refluxing process. The emission and excitation peaks of fabricated cysteine-maltose CDs (CM-CDs) are noticed at 511 and 420 nm, respectively. The as-fabricated CM-CDs displayed average mean size of 3.63 ± 1.12 nm with uniform spherical shape and good quantum yield of 32.81 %. Importantly, the as-fabricated CM-CDs act as a sensor for venlafaxine an anti-depression drug sensing via a fluorescence "turn-off" mechanism. The fluorescence lifetime of CM-CDs was 1.34 ns. The as-fabricated CM-CDs were highly sensitive towards venlafaxine, displaying good linear range from 0.1 to 180 µM with the limit of detection of 75.15 nM. The fluorescence of CM-CDs was reduced with the interaction of venlafaxine, thereby favoring to develop CM-CDs-based cellulose paper sensor for venlafaxine assay. The fabricated sensor was effectively utilized for the quantification of venlafaxine in pharmaceutical and biological samples with good recovery rates (96.01––99.65 %). [ABSTRACT FROM AUTHOR]