Interfacial structure and history dependent activity of immobilised antibodies in model pregnancy tests

Abstract

Experimental studies of antibody adsorption and antigen binding that mimicked the key molecular processes of pregnancy tests were performed using dual polarisation interferometry (DPI). The model tests were built up in stages so that the interfacial structure and dynamics of antibody adsorption could be examined in detail. The near real time data acquisition of DPI also allowed the monitoring of the kinetics of co-adsorption of bovine serum albumin (BSA) into the pre-adsorbed antibody layer, revealing time-dependent clustering. The amount of BSA co-adsorbed was found to decrease steadily with increasing antibody adsorption and the almost constant total layer thickness indicated that BSA molecules mainly filled the gaps within the pre-adsorbed antibody layer. The specific binding capacity of the target antigen was subsequently found to be constant at 0.15 mg m⁻², showing a clear trend of decreasing surface binding capacity with increasing antibody surface packing density.