Oriented immobilization of antibodies onto the gold surfaces via their native thiol groups.

The general approach for site-oriented immobilization of antibodies onto gold supports is reported. The immobilization is carried out using the native sulfide groups of immunoglobulin (IgG). To liberate the thiol groups, the intact IgG was split into two half-IgG fragments without destruction of the binding site of the antibody. The immobilization of half-IgG fragments on the gold surface was carried out by simple adsorption. The antigen binding capacity of the half-IgG modified gold supports is similar to that of the gold surfaces with the traditionally linked antibodies and is much higher than for nonspecifically adsorbed intact IgGs. The immobilized antibodies, according to the proposed approach, maintain high antigen binding constants. The immobilization procedure provides orientation of IgG fragments in terms of the similar distance between the binding site of the antibody and the surface of the gold support, which does not cause the distribution of the apparent affinity constants. The high operational stability of half-IgG modified gold electrodes makes them applicable for analytical applications.