Trimetallic mesoporous nanozyme-mediated lateral flow assay enables ultrasensitive visual simultaneous detection of biological and chemical contaminants.

The vast molecular-weight range of biological versus chemical contaminants limits the ability of current methods to achieve simultaneous detection of mixed contamination within a single assay. Here, we report a colorimetric dual-mode lateral flow assay (DMLFA) using trimetallic mesoporous nanozyme tags (dPdPt-Ir) that unifies sandwich and competitive formats with an ultrasensitive substrate-catalyzed readout on a single test strip, enabling accurate, simultaneous detection of a representative biological contaminant (bacteria) and a chemical contaminant (clenbuterol, CLE). The dPdPt-Ir enhances DMLFA performance by: (1) supplying abundant catalytic sites via a ternary, mesoporous framework to elevate peroxidase-like activity, sensitivity, and signal dynamic range; (2) increasing antibody loading and target capture through a high-roughness mesoporous surface; and (3) providing structural stability through an all-metallic framework for reliable operation in complex matrices. The proposed DMLFA allows simultaneous quantification of E. coli O157 and CLE within 20 min, with LODs of 35 cells/mL and 7.15 pg/mL. It shows wide linear ranges (E. coli O157: 50-1 × 106 cells/mL; CLE: 0.01-100 ng/mL), 100-fold enhanced visual sensitivity, RSD <6.91% and recoveries of 80.37%-111.69%. These results demonstrate its great potential for rapid screening of complex contaminant mixtures in environmental monitoring and food safety applications.