Fluorescence and colorimetric detection of ascorbic acid in beverages using manganese-doped carbon dots nanozyme

This study aimed to present the synthesis of manganese-doped carbon dots (Mn-CQDs) via a straightforward hydrothermal procedure, facilitated by histidine. These Mn-CQDs exhibit enhanced fluorescence and peroxidase-like activities. Utilizing these properties, we developed a dual-mode fluorescence and colorimetric assay for detecting ascorbic acid (AA) in beverages. The addition of AA enhances the fluorescence and reduces the blue oxidized 3,3′,5,5′-tetramethylbenzidine (oxTMB) to a colorless form. The assay demonstrated a robust linear relationship between the changes in fluorescence intensity and absorbance with AA concentration. The limits of detection for AA were 1.54 µM using the fluorescence method and 0.69 µM using the colorimetric method, across detection ranges of 0.5–150 µM and 0.5–70 µM, respectively. The method’s significantly lower LOD compared to existing sensors allows for highly sensitive AA detection, which is critical for precise quantification. The assay was successfully validated in various beverage matrices, showcasing its rapid, efficient, and reliable performance with potential to enhance food safety monitoring.