^{Ding Min， Lu Yizhong}

School of Materials Science and Engineering， University of Jinan， Jinan 250022， China

Abstract

Objective Oxidative stress induced by the imbalance between reactive oxygen species productionand antioxidant defense is a key pathological factor in cardiovascular diseases， neurodegenerative disorders， diabetic complications， and cancers. Antioxidants can eliminate excess reactive oxygen species and protect cells from oxidative damage. Therefore， accurate detection of antioxidants in biological fluids is critical for early disease diagnosis， prognosis， and clinical monitoring. Traditional analytical methods， including high-performance liquid chromatography， mass spectrometry， and electrochemistry， rely on expensive equipment， complicated sample pretreatment， and professional operation， which limits their application in point-of-care testing and large-scale screening. Nanozyme-based sensors have emerged as low-cost and stable alternatives. However， single-atom nanozymes suffer from low catalytic efficiency and single signal output， making themvulnerable to biological matrix interference and incapable of simultaneous multi-antioxidant detection. Diatomic nanozymes with bimetallic synergistic interactions can effectively overcome these limitations. Compared with single-atom nanozymes， cobalt-copper diatomic nanozymes exhibit excellent peroxidase-like activity and an inherent dual-mode signal response. However， complex biological matrix interference and poor discrimination of structurally similar antioxidants remain two major challenges for clinical applications. This study aims to construct a high-performance dual-mode sensing platform based on cobalt-copper diatomic nanozymes for simultaneous qualitative and quantitative detection of multiple antioxidants in complex biological samples.

Methods In this study， a cobalt-copper diatomic nitrogen-doped carbon nanozyme was fabricated via a facile and controllable host-guest confinement pyrolysis strategy. Cobalt and copper precursors were first encapsulated into the porous structure of metal-organic framework hosts through coordination and ion-exchange interactions. During high-temperature pyrolysis， the rigid framework confined the migration and aggregation of metal atoms， successfully forming uniformly dispersed cobalt-copper dual active sites anchored on nitrogen-doped carbon supports. This synthetic strategy achieved precise regulation of the loading， dispersion， and coordination environment of active sites， ensuring stable and uniform catalytic performance. Material characterization confirmed that the prepared cobalt-copper diatomic nitrogen-doped carbon nanozyme exhibited outstanding peroxidase-like activity and excellent photothermal conversion efficiency. Based on these dual properties， a colorimetric-photothermal dual-mode sensing array was fabricated. The colorimetric signal derived from nanozyme-catalyzed TMB oxidation by hydrogen peroxide， producing blue products with characteristic absorption at 652 nm， while the photothermal signal wasgenerated by the photothermal effect of oxidized TMB. Principal component analysis was further combined with the sensing array to reduce data dimensionality and extract feature information， enablingthe discrimination and quantitative detection of multiple antioxidants. The sensing performance was systematically evaluated using standard antioxidant solutions and human serum samples.

Results and Discussion The constructed dual-mode sensing array achieved a linear detection range of 5 μmol/L to 50 μmol/L for common antioxidants， with detection limits ranging from2.45 μmol/L to 8.29 μmol/L. This linear range fully covered the physiological concentrations of typical serum antioxidants， including ascorbic acid， glutathione， and uric acid， meeting the requirements forclinical sample detection. Principal component analysis demonstrated that the first principal component explained 86% of the total data variance， and the cumulative variance contribution of the first two principal components exceeded 94%. The high cumulative contribution rate indicated that the dual-mode signals provided sufficient characteristic fingerprint information， enabling efficient discrimination of structurally similar antioxidants without complex data processing. The recoveries of antioxidant detection in spiked human serum samples were 91.8%~107.2%， with all relative standard deviations lower than 4.6%. The satisfactory recovery and precision verified that the proposed sensing method had excellent anti-interference capability and stable detection performance in complex biological matrices， which effectively solved the matrix interference problem of traditional single-mode sensors and enabledaccurate multi-antioxidant detection in real serum samples.

Conclusion In this study， a high-performance cobalt-copper diatomic nanozyme with dual catalytic and photothermal functions issuccessfully synthesized via a host-guest confinement pyrolysis method. The synergistic electronic interaction between cobalt and copper dual sites significantly improves the peroxidase-like catalytic activity and photothermal conversion efficiency of the nanozyme， providing a reliable material basis for dual-mode sensing. By integrating the colorimetric-photothermal dual-mode sensing array with principal component analysis algorithm， a novel sensing platform isestablished for the simultaneous qualitative identification and quantitative detection of multiple antioxidants in complex human serum. The sensor possesses a wide linear range， a low detection limit， high selectivity， and good reproducibility， effectively overcoming the limitations of matrix interference and poor multi-component discrimination of traditional single-mode detection methods. This study provides a new strategy for the design and fabrication of high-efficiency diatomic nanozyme sensing platforms. It also offers promising technical support for clinical antioxidant detection， early disease warning， and personalized health management. In future research， the coordination structure of diatomic active sites can be further optimized to improve catalytic performance and expand the detection scope of antioxidant analytes.

Keywords： cobalt-copper diatomic nanozyme； nitrogen-doped carbon material； colorimetric-photothermal dual-mode sensing； multi-component antioxidant detection

Get Citation:Ding Min， Lu Yizhong. Preparation and application of cobalt-copper bimetallic catalysts［J］. China Powder Science and Technology， 2026， 32（6）： 1-9.

Received：2026-05-06，Revised： 2026-07-06，Online： 2026-09-09。

Funding： The research was supported by the General Program of the National Natural Science Foundation of China (Grant No. 52172232).

CLC No.：O657.3； TB4

Type Code：A

Serial No.：1008-5548（2026）06-0001-09