Biomass-derived multi-emissive carbon dots-based ratiometric fluorescence and visual detection of residual chlortetracycline hydrochloride and hemin chloride in food matrix

Multi-emissive red fluorescence carbon dots (R-CDs) were synthesized using Stellaria pallida and urea precursors through a solvothermal method, based on which a ratiometric fluorescent sensor was constructed and integrated into a portable dual-mode sensing platform for determining the residual levels of Chlortetracycline Hydrochloride (CTC) and Hemin Chloride (Hemin) in food products. The ratiometric fluorescent sensor achieved limits of detection (LODs) were 13.00 × 10 −3  μM for CTC and 0.74 × 10 −3  μM for Hemin, while the visual detection platform provided LODs of 1.50 × 10 −3  μM and 0.53 × 10 −3  μM, respectively. The relative standard deviation of the spike recovery tests ranged from 0.69% to 1.12%. This work presents a green, low-cost, and highly sensitive dual-analyte sensing strategy combined with a visual readout, offering a reliable platform for on-site food safety monitoring.