A fluorescence “turn-on” sensor for ascorbic acid in fruit juice and beverage based on ascorbate oxidase-like activity of citric acid-derived carbon dots

Citric acid-derived carbon dots (CA-CDs) without any modifications were found to have the ascorbate oxidase (AAO)-like activity. The CA-CDs have high affinity for ascorbic acid (AA), which is similar to natural AAO. The robustness of CA-CDs is greater than that of AAO. Based on the AAO mimetic activity of CA-CDs, a sensitive turn-on mode and natural enzyme-free fluorescence detection method has been developed for AA in some fruit juice and beverage samples with satisfied recoveries. This study provides CDs-based AAO mimetic nanozymes to replace the expensive natural enzymes or heavy metal-based nanozymes, which will show great potential in biological and food assays.