COMPARATIVE-STUDIES ON PHYSICALLY ADSORBED AND CHEMICALLY BOUND IGG TO CARBOXYLATED LATEXES .2.

The aim of the present work is to compare the behavior of physically ( passively) adsorbed and of chemically (covalently) bound IgG to carbox ylated latexes (CLs), In this work we have tried to determine the adva ntages and disadvantages of covalent coupling of antibodies to CLs aga inst the passive adsorption procedure. Physically adsorbed IgG was mea sured by direct UV spectrophotometry at 280 nm. Even when the protein has the same charge sign as its sorbent, adsorption occurs spontaneous ly, and this suggests an adsorption caused by hydrophobic forces. IgG chemically bound using the carbodiimide method was both directly measu red using the bicinchoninic acid reaction (BCA method) and indirectly calculated using UV spectrophotometry. The covalent coupling had an ef ficiency rate of more than 70%. The different electrophoretic behavior shown by the IgG covalently bound to the CL particles versus that of the IgG passively adsorbed on these particles is due to the presence o f the carbodiimide used in those that are chemically bound. Mobility v alues were dealt with using the most recent theoretical approaches, gi ven by Ohshima and Kondo, to obtain information about the protein laye r. The chemical coupling provides a better immunological response of t he IgG-CL complexes. (C) 1995 Academic Press, Inc.