Graphitic nanozyme for visual ascorbic acid sensing in commercial beverages

Ascorbic acid (AA), an essential micronutrient that cannot be endogenously synthesized in humans, plays vital roles in various physiological processes and must be obtained through dietary intake. However, AA is prone to oxidative degradation during food processing, storage, and transportation, leading to significant loss of its bioactivity. These factors underscore the critical need for developing simple, rapid, and accurate methods for AA quantification in food products. Recently, nanozyme–mediated colorimetric sensing has emerged as a promising approach for AA detection, combining the advantages of nanozymes (including cost–effectiveness, high catalytic activity, excellent stability, and scalable production) with the simplicity of colorimetric analysis that enables equipment–free visual detection. Most nanozymes demonstrate optimal catalytic activity exclusively under acidic conditions, while simultaneously exhibiting poor stability in such environments. To address this limitation, we developed an ultra–stable peroxidase (POD)–like CoPt graphitic nanozyme (CoPt@G) through a one–pot chemical vapor deposition (CVD) method and constructed a robust colorimetric AA detection platform. The proposed biosensor exhibits a linear range of 5–60 μM and the detection limit (S/N = 3) of 1.4 μM, with results comparable to most of the related works. Additionally, the proposed sensor demonstrates good selectivity and promising practical application potential for AA detection in commercial beverages. This study develops a simple, rapid visual AA detection method, offering valuable guidance for scientifically informed dietary decisions.