Efficiency of blocking of non-specific interaction of different proteins by BSA adsorbed on hydrophobic and hydrophilic surfaces

Adsorbed BSA produces low density structures (less than a monolayer), which show significant blocking property of non-specific adsorption of different proteins on solid substrates. The efficiency of a pre-absorbed bovine serum albumin (BSA) layer in blocking the non-specific adsorption of different proteins on hydrophobic and hydrophilic surfaces was evaluated qualitatively and quantitatively using infrared reflection spectroscopy supported by spectral simulations. A BSA layer with a surface coverage of 35% of a close-packed monolayer exhibited a blocking efficiency of 90–100% on a hydrophobic and 68–100% on a hydrophilic surface, with respect to the non-specific adsorption of concanavalin A (Con A), immunoglobulin G (IgG), and staphylococcal protein A (SpA). This BSA layer was produced using a solution concentration of 1mg/mL and 30min incubation time. BSA layers that were adsorbed at conditions commonly employed for blocking (a 12h incubation time and a solution concentration of 10mg/mL) exhibited a blocking activity that involved competitive adsorption–desorption. This activity resulted from the formation of BSA–phosphate surface complexes, which correlated with the conformation of adsorbed BSA molecules that was favourable for blocking. The importance of optimisation of the adsorbed BSA layer for different surfaces and proteins to achieve efficient blocking was addressed in this study.