Highly Sensitive Lateral Flow Immunoassay for Clenbuterol and Structurally Similar Beta2-Agonists in Meat

Beta-agonists are growth promoters sparking considerable interest in animal husbandry. However, their numerous negative effects on health have led to a number of restrictions on their presence in agricultural products, which differ depending on the type of preparation and food. In this regard, there is a demand for methods of their mass, rapid, and easy control with strict, focused selectivity. In this paper, a lateral flow immunoassay (LFIA) with clenbuterol (CLE), a priority β2-agonist for food safety, as the main target compound is proposed. The LFIA is based on indirect labeling of specific antibodies by gold nanoparticles via anti-species antibodies. The development of the LFIA involved optimizing the concentrations of immunoreagents and the composition of the reaction mixture (buffer type and pH, ionic strength, detergents, and additional components). In qualitative (visual) mode, the LFIA detects up to 1.0 ng/mL of CLE. In quantitative mode, the detection limit reaches 0.02 ng/mL, surpassing previously described colorimetric LFIAs. The selectivity of the obtained and used monoclonal antibodies allows for the group-specific detection of CLE and structurally close (the presence of a trimethyl residue, similar charge distribution in the benzene ring) common β2-agonists-salbutamol and mabuterol-distinguishing them from other β-agonists, including the widely used β1-agonist ractopamine, which differs in application and biological activity. The assay time is 15 min. The application of the LFIA for meat samples demonstrated that the CLE recovery ranged between 86% and 104%. The obtained results confirm the effectiveness and competitive potential of the developed assay for screening meat products outside of laboratories.