Highly sensitive dual-color lateral flow immunoassay for brucellosis using one-step synthesized latex microspheres
A rapid and sensitive lateral flow immunoassay was developed for brucellosis screening. This lateral flow immunoassay strip was sandwich-format and based on brucella LPS and IgG immunological reaction. The latex microspheres were labeled with Staphylococcal Protein G(SPG) and sprayed on the conjugation pad; the Brucella lipopolysaccharide(LPS), which specific to IgG, was immobilized on the test line of nitrocellulose membrane. In samples contain Brucella antibodies, the latex microsphere(LM)-SPG conjugate would capture the IgG in the serum then the LM-SPG-IgG complex would combine with LPS. So the LMs could be enriched in the LPS immobilized position and showing positive signal. Carboxyl-functionalized latex microspheres were prepared via emulsifier-free emulsion polymerization synthesis and used for detection. The latex microspheres were polyhedral and globoid with an average diameter of approximately 300 nm. Particles of different colours were obtained by using two different dyes. So this LFIA realized dual colour on a test strip. Meanwhile, the dual colour realized whole blood detection without a blood filtration pad. The sensitivity and stability of dual colour LMs-LFIA were better than the serum agglutination test (SAT) and rose bengal plate test (RBPT). This can improve clinical care.