Covalent coupling of antibodies to aldehyde groups on polymer carriers

Abstract

The aim of the present work is to prepare and characterize a functionalized latex with acetal groups on the surface and to obtain the covalent coupling of an a-CRP IgG protein. The acetal latex was synthesized by means of a core-shell emulsion polymerization in a batch reactor. The core was a seed of polystyrene and the shell was obtained by terpolymerization of styrene, methacrylic acid and methacryloylacetaldehyde di(n.methyl)acetal. The latex was characterized by TEM and conductimetric and potentiometric titration, in order to obtain the particle size distribution and the amount of carboxyl and acetal groups on the surface, respectively. Several latex-protein particles with the IgG physically or chemically bound to the surface were obtained by modifying the incubation conditions. In the covalent coupling experiments of the IgG, the protein physically adsorbed was removed by redispersion of the complexes in the presence of a non-ionic surfactant (Tween 20). The latex-protein complexes were characterized from the electrokinetic point of view with the aim to determine the isoelectric point of the complexes and to detect any difference in the electric state of the protein when these molecules are physically or chemically coupled to the surface. The final part of this work was to study the immunoreactivity of several latex-IgG complexes at several experimental conditions. By measuring the change in the turbidity after the addition of CRP antigen into the dispersion, it was possible to compare the immunoreactivity results when the protein is physically or chemically bound to the surface, and to study the effect of the presence of a surfactant in the reaction medium.