The investigator's overall career vision is to develop a research program exploring mineral surface interactions with biological macromolecules in processes that are relevant to biogeochemistry (including environmental chemistry, biomineralization and geomedicine), integrated with an educational initiative that (i) increases the public 's awareness of the impact of biogeosciences in their lives,(ii)illustrates how the core physical sciences provide a language for interpreting natural phenomena whether in the external environment or within the human body, and (iii)increases participation of minorities and women in the physical sciences. One major segment of the career plan is described in the present proposal. The research component is to investigate the unique adsorption and self-assembly of phospholipids at the surface of quartz compared to other oxides. The study is motivated by the observation that quartz ruptures cell membranes, composed primarily of phospholipids, whereas amorphous silica, octahedral crystalline silica (stishovite) and other oxides such as corundum and anatase are relatively benign. No satisfactory model currently exits to explain the different biological activity of the mineral phases. Preliminary thermodynamic modeling suggests that the different bioactivity of oxides is due to differences in crystallography and chemical composition as reflected in oxide surface charge and hydration (hydrophilicity) compared to the hydration of the phospholipids. Differences in surface charge and hydration ultimately affect phospholipid adsorption, self-assembly, and extent of organization or rupture. A major objective of the proposed work is to test this hypothesis using a combination of ab initio calculations and collaborative experimental work. Results could have implications for understanding cellularization in the early stages of the evolution of life, cell adhesion to mineral surfaces, the effect of inhaled dusts on cells in the lung, designing biocompatible medical devices, and industrial applications such as the biobeneficiation of ores during processing. Adsorption and self-assembly of phosphatidylcholine from aqueous solution onto the surfaces of quartz, silica glass, orthoclase and anatase will be studied. The effects of pH and background electrolyte will also be examined. Isotherms and microcalorimetry will provide adsorption energies. These experiments will be performed in collaboration with Prof. Anant Menon and Prof. Thomas Record, Department of Biochemistry, University of Wisconsin-Madison (UW). Attenuated Total Reflectance-Fourier Transform Infra-Red spectroscopy (ATR-FTIR) spectroscopy combined with quantum chemical cluster calculations of energies and vibrational frequencies will indicate which specific functional groups of the phospholipids interact with the mineral surface. Morphological changes in the phospholipid self-assembled surface aggregates, which reflect changes in interfacial solvation, will be monitored using Atomic Force Microscopy. Vibrational spectroscopy and AFM experiments will be accomplished in collaboration with Prof. Robert Hamers, Department of Chemistry, UW. As part of the career-long educational initiative, during the period of this project, the P.I. and her research group will develop a novel exhibit at the Geology Museum, UW, that demonstrates the interdisciplinary nature of the biogeosciences, and emphasizes the concept that similar fundamental physico-chemical principles underlie natural geochemical and geomedical processes. The exhibit will highlight results from the research proposed above, and from other projects of our research group. The strength of this approach is that it integrates the research efforts with the broader educational initiative. The impact of this novel exhibit may be estimated from the greater than 25,000 visitors annually to the Geology Museum at UW. Design of the exhibit, short-term feedback and long-term evaluation of the project, its modification, and expansion to other museums in the upper Mid-West will be conducted in collaboration with the Museum Director, Dr. Richard Slaughter and UW's Centre for the Integration of Research, Teaching and Learning (CIRTL), a new NSF funded Centre for Learning and Teaching. The involvement of a post-doctoral associate, graduate and undergraduate students in all aspects of the proposed work will provide both research and outreach training to the future academic workforce in the physical sciences.
