PdIr bimetallic nanozyme engineered metal-organic frameworks integrated dual-mode sensor toward Stx2 detection in food

Colorimetric/fluorescent sensor for Stx2 based on UIO-66@PdIr was established. • Aptamer as a specific capture element enhanced the accuracy of the detection. • PdIr bimetallic nanoparticles exhibited excellent peroxidase-like activity. • UIO-66 as carrier enhanced PdIr loading and offered inherent fluorescence. • The sensor showed low LOD of 0.039 (colorimetric) and 0.0097 ng/mL (fluorescent). Shiga toxin II (Stx2) has attracted extensive attention due to its toxicity and pathogenicity, making the development of sensitive detection methods urgent. This study constructed a dual-mode sensing platform for the sensitive detection of Stx2 in food. Composite material UIO-66@PdIr with peroxidase-like activity and fluorescent properties was synthesized and combined with cDNA as the signal probe, while aptamer-modified magnetic beads served as the capture probe. Specific binding of Stx2 to the aptamer triggered the release of the signal probe, enabling colorimetric and fluorescence signal readout. The colorimetric mode showed a linear range of 0.05–100 ng/mL with an LOD of 0.039 ng/mL, and the fluorescence mode exhibited 0.01–1000 ng/mL with an LOD of 0.0097 ng/mL. Additionally, this method was successfully applied to the detection of Stx2 in food, and the recovery rates were 94.33% ∼ 102.20%. It indicated that the constructed sensor holds great practical potential for Stx2 detection. Download: Download high-res image (137KB) Download: Download full-size image