WAYS OF IMPROVING THE SPECIFICITY OF THE LATEX AGGLUTINATION REACTION

Abstract

The article describes research on the development of new diagnostic test systems operating on the basis of latex agglutination reaction, in which polymer microspheres are used as bioligand carriers instead of erythrocytes. Polymeric microspheres to be used as bioligand carriers must satisfy the following requirements: narrow size distribution, diameter of 5 microns. Besides, they must be characterized by aggregative stability in water and buffer solutions and be contained functional groups in the surface layer for linking with the functional groups of the protein. They are crosslinked particles obtained by copolymerization of styrene and divinylbenzene on polystyrene seed particles 1.5 microns in diameter with a narrow size distribution followed by modification by chloromethylation and amination by ethylenediamine. To increase the hydrophilicity of the surface of the polymer microspheres and to reduce nonspecific adsorption of proteins dextran was immobilized on the surface of the particles by covalent binding with amino groups of particles using Maillard reaction. It was found that diagnostic test systems, where modified dextran particles were used as carriers of the bioligand (Vi-antigen), are characterized by insufficient specificity and require additional modification of the surface of the polymer microspheres to eliminate its non-specific interaction with the surface of the polymer plate used for the latex agglutination reaction. A nonionic surfactant (Tween 80) proposed for the surface modification and used in a certain concentration provides the best reaction specificity.