Bimetallic FeV supported on g-C3N4 with augmented POD-like activity for efficient detection of D-amino acids

A Fe/V-CN nanozyme with synergistically enhanced POD-like activity was rationally designed. • A sensitive cascade colorimetric platform for detecting gastric cancer-related D-amino acids was successfully constructed. • The assay supports reliable quantification of D-amino acids in complex human saliva matrices. The development of a practical and reliable cascade colorimetric method for detecting D-amino acids (DAAs) provides a promising tool for the prevention and preliminary diagnosis of gastric cancer. Herein, a bimetallic Fe V supported on graphitic carbon nitride (Fe/V-CN) nanozyme was rationally designed and synthesized via a simple annealing strategy. The atomic dispersion of Fe and V species, along with their coexisting multivalent states (Fe 2+ / 3+ , V 4+ / 5+ ) synergistically boosted the intrinsic peroxidase-like (POD) activity to Fe/V-CN, which were characterized by a high substrate affinity ( K m of 0.078 and 0.083 mM for TMB and H 2 O 2 ) and an accelerated catalytic turnover ( V max of 4.94 × 10 −7 and 7.76 × 10 −7  M·s −1 , respectively). Leveraging this improved activity, a cascade colorimetric sensing system was developed by integrating Fe/V-CN with D-amino acid oxidase (DAAO) for the specific detection of DAAs. The platform exhibited favorable analytical performance for D-proline (D-Pro) and D-alanine (D-Ala), offering wide linear ranges of 0–200 μM and 0–160 μM and low detection limits of 0.93 μM and 1.45 μM, respectively, combined with acceptable selectivity against common interferents. For real-sample analysis, the platform was successfully implemented in determine DAAs in human saliva, delivering satisfactory recoveries (95.8–105.7%) and good precision (RSD < 3.5%). This work presented a synergistic Fe/V bimetallic nanozyme and a practical sensing strategy, demonstrating the feasibility of DAAs detection in complex biological matrices. Download: Download high-res image (70KB) Download: Download full-size image