Sensitive Lateral Flow Immunoassay of Beta-Agonist Mabuterol in Meat Samples Using Au@CeO2 Nanoparticles as a Catalytic Signal-Enhancing Label

The use of beta-adrenomimetics (beta-agonists) to enhance the productivity of farm animals can lead to their unintended ingestion by humans through contaminated food products. To ensure the effective detection and prevention of these risks—which arise even at low contaminant concentrations—a highly sensitive lateral flow immunoassay (LFIA) was developed for the detection of the beta-agonist mabuterol (MAB). We have comparatively evaluated two nanoparticle labels: conventional gold nanoparticles (AuNPs) and bimetallic core@shell Au@CeO2 nanoparticles (Au@CeO2 NPs). The assay protocols were systematically optimized, including immunoreagent concentrations, reaction media composition, and assay time. Exploiting the peroxidase-mimetic activity of Au@CeO2 NPs, a catalytic amplification strategy was integrated with the LFIA protocol. This was achieved by treating the test strip with a 3,3′,5,5′-tetramethylbenzidine-based substrate. Compared with the traditional AuNPs-based LFIA, Au@CeO2 NPs provided a 2.6-fold decrease in the instrumental limit of detection (0.6 ng/mL) in the one-step catalytic format and a 6-fold decrease (0.26 ng/mL) in the two-step catalytic format. The total assay time was 18 min. An assessment of matrix effects using beef, pork, and chicken meat extracts yielded detection rates ranging from 80% to 139%, indicating potential applicability of the developed method. Furthermore, the developed assay format, utilizing the catalytic properties of Au@CeO2 NPs, provides a promising platform for sensitive detection of other low-molecular-weight toxic contaminants in food safety monitoring.