PARTICLE ENHANCED IMMUNOASSAYS STABILIZED BY HYDRATION FORCES - A COMPARATIVE-STUDY BETWEEN IGG AND F(AB')(2) IMMUNOREACTIVITY

In previous publications we have discussed the stabilization mechanism of hydration forces as applied to the development of latex agglutinat ion tests. We describe here how we have obtained stable and reactive I gG-latex conjugates in a high-ionic-strength reaction buffer. To this end we have made agglutination tests with polystyrene beads sensitized with IgG, measuring the immunoaggregation reaction with human C-react ive protein in a stopped-flow nephelometer. The results are compared t o those obtained with a F(ab')(2)-latex conjugate with similar antibod y molecule coverage. Adsorption isotherms of F(ab')(2) and IgG on late x at pH 7.2 were obtained to study the affinity of these antibodies fo r the surface. The results of the electrokinetic characterization of t he antibody-latex conjugates agree satisfactorily with those obtained from stability studies. This research throws light upon the use of hyd ration forces as a new approach to stabilizing immunoassay reagents th at are colloidally unstable in physiological reaction buffers. (C) 199 8 Elsevier Science B.V.