Innovative engineering of red-emissive carbon dots for profoundly sensitive and recyclable determination of malachite green in fish tissue.

Accurate measurement of hazardous synthetic dye is highly attractive for environmental and food safety inspection. Herein, red fluorescent carbon dots (R-CDs) are meticulously engineered by employing Azure A as a fluorophore to optimize the optical characteristics, thereby promoting high-efficiency fluorescence emission at 648 nm. The constructed R-CDs demonstrate excitation-independent characteristics remarkable photostability and superior water solubility. It is encouraging that the developed R-CDs demonstrate a specific response to MG, effectively differentiating it from other substances. The engineered R-CDs demonstrate concentration-responsive fluorescence quenching towards MG, exhibiting rapid response time with a well-defined linear detection range of 0.09-8.21 μM and ultralow detection limit of 24.2 nM. Furthermore, the spike recovery analysis of MG in fish tissue demonstrated robust performance with recoveries of 97.63-106.0 % (RSD <6.37 %), highlighting the analytical reliability for MG identification in aquatic products. The aforementioned results underscore the significant potential of the developed R-CDs for MG detection in aquatic products and bolster their application in food safety inspections.