Colorimetric sensor array based on a bimetallic PtPd nanozyme for simultaneous discrimination of multiple antioxidants.

The identification and quantification of antioxidant species are of paramount importance, as these compounds play vital roles in regulating redox balance, cellular signaling, immune responses, and their abnormal levels serve as crucial markers in the onset the progression of various diseases. Traditional single-analyte detection methods often suffer from limited specificity and are incapable of capturing the complexity of biological systems involving multiple coexisting antioxidants. In contrast, colorimetric sensor arrays offer a powerful alternative by generating unique, fingerprint-like response patterns that enable the simultaneous detection and differentiation of structurally or functionally similar analytes. In this study, we developed a triple-channel colorimetric sensor array utilizing a bimetallic PtPd nanozyme with peroxidase-mimicking activity and 3,3',5,5'-tetramethylbenzidine (TMB) as the chromogenic substrate. By strategically incorporating three distinct pH conditions as independent sensing channels, the system generated differential colorimetric responses that enabled both the qualitative discrimination and quantitative analysis of five representative antioxidants: ascorbic acid (AA), citric acid (CA), cysteine (CYS), tannic acid (TA), and uric acid (UA). The sensor array demonstrated excellent selectivity, sensitivity, and reproducibility in complex sample environments. Its performance was rigorously validated through successful identification of target antioxidants in human serum samples, as well as in binary, ternary, and multicomponent mixtures. These findings highlight the strong discriminative capability and real-sample applicability of the proposed PtPd nanozyme-based colorimetric sensor arrays, underscoring its great promise as a versatile platform for biomedical diagnostics, disease biomarker screening, and antioxidant-related health monitoring.