Bioinspired amino acid-functionalized carbon dots nanozymes with enhanced peroxidase-like activity for sensitive detection of GSH in food

The development of nanozymes that exhibit high catalytic activity remains challenging. Herein, carbon dots (CDs) functionalized by different acidic, neutral and basic amino acids were synthesized. The CDs modified with the L-aspartic acid (Asp-Fe-CDs) showed bright blue fluorescence and remarkable peroxidase-like activity. The specific activity of Asp-Fe-CDs was greatly enhanced around 4 times compared to Fe-CDs without the L-aspartic acid. The excellent enzymatic activity of Asp-Fe-CDs was ascribed to carboxyl group of L-aspartic acid in the side chain. Given the advantages of Asp-Fe-CDs, a dual-mode sensor was developed for GSH detection. The limits of detection were 0.189 μM and 0.296 μM for fluorimetry and colorimetry, respectively. Moreover, the sensor was used to detect GSH in food with satisfactory results. In summary, this research not only proposes a new strategy for the design of carbon dots nanozymes but also develops a multimode sensing platform for GSH detection.