Effects of surface characteristics on non-specific agglutination in latex immunoagglutination antibody assay

To monitor the non-specific agglutination (NSA) in latex immunoagglutination assay, antigen-coated structured latex particles, which have carboxyl and sulphonate groups as hydrophilic domains, were tested for an antibody assay. Sulphonated particles showed NSA in high antibody concentrations, where no surface antigen left to match with. This was further justified with the more stable highly sulphonated particles, which showed higher degree of NSA. It can therefore be confirmed that sulphonate groups cause (or at least promote) NSA, while carboxyl groups do not. Surface coverage over 17% was not fully utilized for antigen-antibody reaction, due to the prozone effect. The difference in sensitivity of particles was explained in terms of our new explanations on the governing interactions of protein adsorption.