Abstract
<title>Abstract</title> <p>This study developed a colorimetric detection platform based on a sulfur-doped bimetallic nanozyme (FePd₂S₄) for the detection of chlorogenic acid (CGA) in medicinal plants. FePd₂S₄ demonstrate peroxidase-like activity, which enables it to oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) into a blue oxidation product (oxTMB). The introduction of CGA enhances the redox characteristics of the nanozyme, strengthening the blue signal of oxTMB and significantly increasing the corresponding ultraviolet-visible (UV-vis) absorption intensity. Based on this phenomenon, an UV-vis detection model was established for CGA, achieving a linear range of 1–50 µg/mL, with a detection of limit (LOD) of 0.15 µg/mL. To further enhance practicality, a smartphone-integrated colorimetric sensing platform for the detection of CGA was constructed with RGB values by the "Color Grab" application. This model is also applicable to the detection of CGA within the linear range of 1–50 µg/mL, with a LOD of 0.45 µg/mL. Furthermore, the dual-modal detection platform was successfully employed in the actual detection of CGA in herbs. In comparison with the UV-vis detection mode, the smartphone-integrated colorimetric platform presents the advantages of straightforward operation, portability, rapidity, and low cost. This work provide a, a novel colorimetric approach for utilizing a sulfur-doped bimetallic nanozyme as a precise tool for the detection of CGA, which has a significant potential for application in food quality and pharmaceutical analysis.</p>