Simultaneous total antioxidant capacity assessment and ascorbic acid accurate quantification utilizing a H2O2-independent colorimetric-fluorescent sensor array

The analysis of nutritional components in food samples is complicated by the presence of structurally and functionally similar antioxidants. To address this challenge, fluorescent-colorimetric dual-mode sensor arrays have emerged as a promising solution. In this work, we successfully developed oxidase-like carbon dots (Fe-CDs) through a straightforward Fe-surface modification approach. The Fe sites in Fe-CDs, coordinated with oxygen, lower the activation energy for oxidase catalytic reactions, significantly enhancing the oxidase-like activity. Building on this, a novel H 2 O 2 -independent colorimetric-fluorescent sensor array was constructed for selectively identifying and quantifying total antioxidant capacity (TAC) in both food and biological samples. The system successfully discriminated TAC levels among five common fruit juices and further extended its application to in vitro analysis for distinguishing between normal, senescent, and cancerous cells. At the same time, Fe-CDs demonstrated excellent accuracy performance in detecting ascorbic acid TAC in fruit juice based on colorimetric-fluorescent methods, with detection limits of 0.9 μM and 1.8 μM as well as linear ranges of 2.5–60 μM and 5–100 μM, respectively. This study not only highlighted the development and applications of novel oxidase-like carbon dots but also showed the potential of advancing food nutrition assessment and safety monitoring.