Novel electrochemical sensor with chiral recognition function prepared from N-CDs and cobalt-based nanomaterials for the detection of tyrosine enantiomers in food

A novel chiral electrochemical sensor was fabricated via the assembly of chiral nitrogen-doped carbon dots (N-CDs) with cobalt-based nanomaterials (Co@CoO) for the rapid discrimination and quantification of tyrosine enantiomers (L/D-Tyr). The sensor has a wide linear range of 1–120 µM and low detection limits of 0.64 µM for L-Tyr and 0.3 µM for D-Tyr. The synergistic interactions between N-CDs and Co@CoO amplify stereoselective recognition, yielding a chiral current ratio (ΔI = I_L/I_D) of 1.65, which outperforms those of previously reported sensors. The chiral recognition mechanism was elucidated using cyclic voltammetry, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, circular dichroism spectroscopy, Zeta potential analysis, and molecular dynamics simulations. The sensor demonstrates exceptional selectivity, stability, reproducibility, and reusability performance, and was successfully applied to the detection of L/D-Tyr in skim milk and yogurt. Notably, this sensor is the first to identify abnormally elevated D-Tyr levels in expired food products, suggesting a potential correlation between amino acid racemization and food quality deterioration. This study establishes a robust platform for chiral recognition in complex food matrices.