Bright orange-emissive carbon quantum dots as an ultrasensitive nanoprobe for new coccine determination in food samples

In this study, an ultrasensitive fluorescence method based on bright orange-emissive carbon quantum dots (OE-CQDs) was for the first time developed for the detection of new coccine (NC). The OE-CQDs were synthesised by a one-pot solvothermal method with saffron T as precursor. The detection mechanism was based on the interaction between OE-CQDs and NC, where the fluorescence of OE-CQDs was inhibited by NC via inner filter effect (IFE) and static interaction. The OE-CQDs probe exhibited high selectivity and good anti-interference ability towards NC sensing. A linear relationship with the concentration of NC in a range of 0.01–20.0 µmol L −1 and a detection limit as low as 1.8 nmol L −1 were obtained. The developed fluorescence method was successfully applied for NC determination in commercial food samples, including dried waxberry, haw flakes, watermelon frost lozenges, strawberry jam and energy drink, with satisfactory results were achieved. The recoveries were in a range of 97.0–104.0% and the relative standard deviations (RSDs) were less than 3.74%. This work highlights the great potential of using long-wavelength emissive CQDs as nanoprobe to achieve enhanced sensitivity in food additives sensing.