Abstract
Clostridium difficile is one of the primary causative agents of nosocomial antibiotic-associated diseases. Early detection and prevention are effective strategies to curb disease transmission, which often requires highly sensitive point-of-care testing (POCT) methods. Although lateral flow immunoassay (LFIA) technology-known for its convenience, speed, and cost-effectiveness-has gained prominence in POCT, its application in early screening remains limited due to relatively low sensitivity. Herein, a two-stage cascading enhancement strategy based on reductase-like and peroxidase-like activities of nanozyme to construct a colorimetrically enhanced LFIA platform is proposed. Specifically, Zn(2+)-doped WO(X) (Zn/WO(X)) loaded with Au nanoparticles (Zn/WO(X)@Au) first generates an initial colorimetric signal through immunochromatography. Subsequently, in situ light-induced deposition of Pt creates Zn/WO(X)@Au@Pt, which exhibits enhanced peroxidase-like activity based on optimal band structure between the components for colorimetric signal amplification. As a result, a 500-fold enhancement in the visual limit of detection (LOD) is achieved. Moreover, the fitted LOD based on grayscale analysis for Clostridium difficile toxin B (Tcd B) reaches 0.01 ng mL(-1). This strategy not only maintains the operational simplicity of LFIA but also considerably strengthens the colorimetric signal, offering a novel approach for highly sensitive colorimetric-enhanced LFIA detection.