Two-dimensional reflectometry visualisation of antigen-antibody binding on solid surfaces

A two-dimensional imaging method for immunological reactions on flat surfaces is described. Antigen-antibody reactions were established at antigen coated silicon surfaces with the use of different techniques such as application of small drops of antibodies, radial diffusions of antibodies in antigen containing agargel gel, cross diffusion of antibodies and anti-antibodies, and double diffusion of antigen and antibody. The amount of protein on the dried surfaces was measured using reflectometry in which the reflected intensity of plane polarised light, falling on the surface at the so called pseudo-Brewster angle is measured. Images of protein distributions were then obtained by scanning the light source over the sample. Thus, simple adsorption of antibodies and different types of adsorbed immunoprecipitates could be visualised in a two-dimensional manner. Illustrative and dramatic images were obtained which give a new angle of approaching and interpreting antigen-antibody binding at solid surfaces. (C) 1997 Elsevier Science B.V.