Preparation of an antigen-sensitive hydrogel using antigen-antibody bindings

An antigen-sensitive hydrogel was prepared by the application of the antigen-antibody binding at cross-linking points in the hydrogel. As antigen, Rabbit IgC was used while Goat anti-Rabbit IgC served as an antibody. As a reference, PAAm hydrogel was also prepared. After swelling of the PAAm and antigen-antibody hydrogel attained equilibrium in the phosphate buffer solution, Rabbit IgC as a free antigen was added into the solution. The addition of a free Rabbit IgC slightly decreased the swelling ratio of the PAAm hydrogel with no antigen-antibody complex. Contrary to this, the antigen-antibody hydrogel was swollen. Further investigation of the swelling changes revealed that the complex between Goat anti-Rabbit IgC and Rabbit IgC immobilized in the antigen-antibody hydrogen is dissociated by the addition of free native IgC. The Rabbit IgC-sensitive swelling of the antigen-antibody hydrogen was explained by the decrease in the cross-linking density in the hydrogel.