Development of a high-sensitivity latex reagent for the detection of C-reactive protein.

Various convenient and high-sensitivity immunoassays based on luminescent oxygen channeling and chromatographic techniques have been developed in recent years. This study focused on the latex agglutination immunoassay because it is a simple, homogenous immunoassay, which is also cost effective. We developed a highly sensitive latex reagent and examined the method of antibody conjugation on the latex particle surface. We introduced spacer amino acids in the latex surface to investigate the relationship between the amino acid spacer and the binding of an anti-C-reactive protein (anti-CRP) antibody as well as to investigate the resulting reactivity of the latex reagent to antigen. Because the distance between the latex particle and the antibody is equal in each case, differences in immunoreactivity are attributed to the structure of the amino acid side chain (R). Thus, reactivity of the latex reagent depends on the inorganicity and organicity of R. We suggest that a useful amino acid spacer has an inorganicity-to-organicity ratio of approximately 2.