A correlative study of the measurement of protein adsorption to steel, glass, polypropylene, and silicone surfaces using ToF-SIMS and dynamic contact angle analyses

Surface analyses of substrates contaminated with varying levels of bovine serum albumen (BSA) were performed. Samples of steel, glass, polypropylene (PPE) and silicone were immersed in solutions of varying concentrations of BSA and analysed by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and dynamic contact angle (DCA) analysis. Contact angle measurements were observed to change as a function of BSA solution concentration. The hydrophilic steel and glass surfaces showed an increase in contact angle with increasing BSA solution concentration while, conversely, the hydrophobic PPE and silicone substrates showed a decrease in contact angle with increasing BSA solution concentration. Comparative semiquantitative measurements were made from the ToF-SIMS data using the relative intensities of signals characteristic of the BSA and substrate under study. These measurements were also seen to change as a function of BSA solution concentration and good correlations between the ToF-SIMS data and DCA results were observed, The sensitivity and utility of the DCA technique to monitor adsorption to the substrates studied are demonstrated.