Latex particles by emulsion and dispersion polymerizations: sensitization with specific antigens of leptospirosis and application to immunoagglutination

Abstract

The controlled synthesis of polymer nanoparticles is of great interest in the production of latexes with well defined characteristics. These products can be applied in biomedicine as carriers of biomolecules (e.g. proteins and enzymes), and in particular as latexes for immunoassays used for example in immunoagglutination test, which allow amplify the antigen–antibody reaction, being simple, quick and inexpensive diagnostic tools. The synthesis of polystyrene (PS) latex particles and of core–shell particles, with controlled size distribution, functional groups and surface charge densities is considered here. PS latexes were synthesized in the 100–1100 nm diameter range, by either emulsion or dispersion polymerization. Such latexes were then used as seeds in emulsion copolymerizations of styrene and a functional monomer (methacrylic acid or glycidyl methacrylate), thus producing particles with carboxyl or epoxy functionalities, respectively. Changes in the polymerization recipes employed under batch operation were analyzed. Latex characterization involved measurements of mean particle diameters, the polydispersity index, functional group densities and zeta potential. Finally, latexes were sensitized (by either physical adsorption or covalent coupling) with specific antigens to obtain latex–protein complexes, and one of them was tested as agglutination assay for detecting leptospirosis disease in bovine samples, as an example of the potential application of the latexes produced.