Silicon-based bimetallic nanozyme-enhanced immunochromatographic strips for highly sensitive simultaneous detection of multiple environmental pollutants

The widespread distribution of food and environmental pollutants such as heavy metal ions, antibiotics, and illegal additives is a major concern for the human living environment. Achieving highly sensitive, universal, and simple detection of these pollutants is still a challenging task. This study developed a multifunctional, highly sensitive, multichannel immunochromatographic detection method based on silicon-based bimetallic nanozymes-mediated (Si@Au/Ir) signal amplification. This method skillfully introduced the gold/iridium (Au/Ir)-loaded bimetallic nanozyme on a silicon (SiO₂) core into the immunochromatographic strip, constructing a multichannel detection platform for the simultaneous detection of three pollutants: cadmium ions (Cd²⁺), clenbuterol (CLE) and gentamicin (GM). The Si@Au/Ir nanozyme uses the high specific surface area and excellent stability of the SiO₂ core to precisely modify the Au/Ir nanoparticles, significantly improving the dispersibility and catalytic efficiency of the nanozymes. This process ensured the uniform distribution of nanoparticles and significantly enhanced detection sensitivity and signal strength. The Si@Au/Ir nanozymes not only exhibited excellent peroxidase-like (POD) catalytic activity but also maintained superior catalytic performance due to its unique structural design, even when specifically binding to target pollutants with high specificity. By integrating the multichannel detection system and the Si@Au/Ir nanozymes, this method can simply, sensitively, and quickly detect Cd²⁺, CLE, and GM in environmental and food samples, with detection limits as low as 1 pg/mL. Detection can be completed within 18 min. In addition, this method demonstrated excellent stability and repeatability (Relative Standard Deviation, RSD < 8.7 %) and significantly improved detection reliability and practicability. It showed broad application prospects for on-site and real-world environmental pollutant detection.