CONICET | Buscador de Institutos y Recursos Humanos

The controlled synthesis of polymer nanoparticles is of great interest since latex with well defined characteristics such as particle size distribution, type and density of surface groups can be obtained. Nanoparticles can be applied in biomedicine as carriers of biomolecules (eg proteins, enzymes), and in particular for immunoagglutination assay (IA). An IA consists in detecting specific antibodies (or antigens) in biological samples by the use of latex particles sensitized with antigens (or antibodies) on their surface. Depending on the latex particle size the agglutination reaction can be detected in different ways. When particles of around 1000 nm are employed the IA is performed in U well microtitre plates, resulting in a negative reaction when particles are deposited in the bottom and a clear point is observed; or in a positive reaction when a diffuse mantle is observed instead of the clear point, thus indicating agglutination.Dispersion polymerization (DP) is an effective method for synthesizing (in a single step) particles with diameters from 500 to 10000 nm. The synthesis of polystyrene (PS) latex particles and of core-shell particles, with controlled sizes, functional groups and surface charge densities is here considered. PS latexes were synthesized by DP in the 900-2900 nm diameter range. One of them was then used as a seed in emulsion copolymerizations of styrene and methacrylic acid, thus producing particles with carboxyl functionality. Changes in the polymerization recipes were evaluated such as the composition of the dispersion medium, and the amount of steric stabilizer, initiator and monomer. Latex characterization involved the measurement of mean particle diameters, polydispersity index, surface charge and functional groups densities, critical coagulation concentration, and electrokinetic properties. Finally, latex-protein complexes (LPC) were obtained by employing recombinant proteins of the parasite Toxoplasma gondii (responsible of Toxoplasmosis), and the sedimentation capability of the LPC was tested.