Understanding the structure and behaviour of proteins adsorbing at key biomaterial surfaces is both challenging but also critical to designing implants that interact favourably with the body. Here, we report the first use of the powerful surface analysis technique neutron reflectometry to characterise a stainless steel surface and the adsorption of key proteins found in the blood plasma thereupon. The challenges of producing a thin film that is representative of the surgical steel alloy are described, as well as the combination of sophisticated surface study techniques such as quartz crystal microbalance (QCM) and neutron reflectometry to study the structure of the adsorbed protein layer in situ at the angstrom-scale.
It was found that fibrinogen, a key component in the blood clotting mechanism, does not adsorb in a simple side- or end-on configuration as often assumed in the literature, but rather in a more complex state, signifying its likely unfolding or denaturation on the surface. The extent of adsorption was also found to be slightly, but significantly different on a chromium oxide surface, raising questions about the veracity of the long-held assumption that the uppermost layer of a stainless steel surface may be considered to be entirely Cr2O3.
This new and powerful approach is now being extended to other key blood plasma proteins and biomaterials.
Wood, M. H.; Browning, K. L.; Barker, R. D.; Clarke, S. M. J. Phys. Chem. B, 2016, 120, 5405.