| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2016) | |
| Biomaterial Surfaces & Interfaces | Wednesday Sessions |
| Session BI-WeM |
| Session: | Biomolecule/Material Interactions |
| Presenter: | Anton Stampfl, Australian Nuclear Science and Technology Organisation, Australia |
| Correspondent: | Click to Email |
Adsorption, surface complexation and reactivity of biological molecules on inorganic surfaces and interfaces is pervasive throughout an enormous range of fields such as chemistry (geochemistry, biochemistry), biotechnology (medical implants, biosensors, tissue engineering, bioelectronics, biomimetics and artificial photosynthesis), radiation technology (radiation damage and detection), colloid chemistry, surface chemistry and physics. Hydrogen and its interaction at surfaces clearly plays a pivotal role in the ultimate functionality of many biologically-based surfaces. Through the hydrogen’s subtle interaction with the tethering surface, or interface, and the surrounding wet environment can and does lead to a multifaceted response to changes in temperature, pH, radiation etc.
Inelastic neutron spectroscopy is the domain of vibrational spectroscopic studies on bulk materials. At first sight, surface studies using such a method, with relatively low neutron flux rates and largish sample size, seems a totally hopeless task. There are, however, exceptions to this rather bullish view, where the surface dominates the scattered signal due to huge surface to volume ratios and large scattering cross-sections from adsorbate molecules, that incorporate for example, hydrogen, which neutrons are supremely sensitive to.
The deposition of amino acids and carbonyl-sulphide onto oxide surfaces is a fruitful area of discovery in the field of prebiotic formation of peptides and an example of how neutron spectroscopy makes significant contributions to the understanding of the subtle chemistry between adsorbate, substrate and surrounding environment. In this series of studies the deposition of amino-acids onto alumina from solution and in the presence of OCS is investigated by both inelastic neutron spectroscopy and high resolution photoemission which allows both the vibrational and electronic structure to be determined for these incredibly interesting systems. Studies focused on the extent of adsorption at various pH's, the character of each adsorbate (zwitterionic, basic, acidic), and the number of discrete surface sites of adsorption. Results show strong chemisorption of amino acids through an ester type bond with the alumina surface across a range of pH. Direct sorption of the amine group with alumina is observed only at pH 9. Formation of multilayers and/or peptides can also occur in conjunction with OCS absorption.