A novel route for fabrication of yellow emissive carbon dots for selective and sensitive detection of vitamin B12

This study pioneers a sustainable strategy for synthesizing yellow-emissive carbon dots (Y-CDs) using expired rabeprazole sodium tablets, thereby transforming pharmaceutical waste into valuable nanomaterials. The as-prepared Y-CDs displayed a high quantum yield of 48.89%, strong photostability, and pronounced environmental resilience. These attributes establish their potential as reliable fluorometric probes. The fluorescence of Y-CDs was effectively quenched by vitamin B12 through a dual mechanism involving the inner-filter effect (IFE) and static quenching. Under optimized conditions, the fluorescence intensity ratio (<i>F</i>⁰/<i>F</i>) showed excellent linearity in the range of 0-300 μM and achieved a detection limit of 8.0 nM (S/N = 3). The developed method demonstrated high accuracy (recoveries of 96.8-105.9%) for pharmaceutical formulations. Beyond its analytical merits, this work introduces a green nanotechnology route that addresses pharmaceutical waste management by converting expired drugs into efficient, multifunctional nanomaterials.