CeO2@Ag-mediated catalytic amplification competitive immunochromatography for ultrasensitive detection of carbofuran

Conventional immunochromatography is limited by insufficient sensitivity and high consumption of monoclonal antibodies, restricting its practical application for trace analysis. Herein, to overcome these limitations, we design a signal amplification strategy based on a CeO 2 @Ag nanocomposite with enhanced peroxidase-like activity and colorimetric properties. The hollow CeO 2 nanospheres offer a high surface area for loading AgNPs, which serve as both electron transfer mediators and peroxidase-like activity to enhance catalytic capacity. By leveraging the multivalent interactions between the primary and secondary antibodies, this approach minimizes carbofuran antibody (mAb 1 ) consumption while maximizing the exposure of its active binding sites. This rational design thereby refines the competitive immunoassay and enables a significant sensitivity boost via signal amplification. The developed CeO 2 @Ag-based immunochromatography achieved a detection limit of 0.087 ng/mL for carbofuran. Moreover, Tetramethylbenzidine (TMB)-mediated catalytic mode significantly extended the linear detection range to 0.08–3.0 ng/mL. Validation in cowpea and lettuce matrices gave average recoveries of 80.35%–108.92% with relative standard deviations below 12.89%, demonstrating excellent practical applicability for sensitive and cost-effective carbofuran monitoring.