Cobalt Single-Atom Nanozyme-Enabled Multimodal Lateral Flow Immunoassay for On-Site Ultrasensitive Detection of Tetracycline Residues in Agri-Food Products
Rui Huang, Tibebu Tsegaye Zigale, Hui Meng, Li Wang, Qinwen Dong, Kun Zeng, Zhen Zhang
Abstract
Tetracycline (TC) residues in agricultural products pose serious food safety risks, necessitating sensitive and field-deployable detection tools. Conventional lateral flow immunoassays (LFIAs) based on gold nanoparticles (AuNPs) are widely used but suffer from limited sensitivity and high cost. To overcome these challenges, we developed a cobalt single-atom nanozyme (CoSAN) using a template-pyrolysis strategy. The resulting Co–N 5 coordination structure exhibited excellent peroxidase-like activity ( K m: 0.622 mM for TMB, 0.294 mM for H 2 O 2 ), generating • OH, • O 2–, and 1 O 2 to enhance both colorimetric and chemiluminescent signals. A multimodal LFIA platform was constructed by integrating CoSAN, enabling colorimetric screening, catalytic amplification, and chemiluminescence quantification. Detection limits reached 0.091, 0.062, and 0.056 ng/mL, representing 43-, 63-, and 70-fold sensitivity improvements over those of AuNP-LFIAs. Application to real milk and honey samples showed no TC levels above the regulatory limits. This study presents a robust, sensitive, and cost-effective approach for on-site food contaminant screening.