Biominerals, Fibres, and Soft Materials at the Nanoscale

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My research program is focused on mechanical properties and processes at the nanometer scale, and developing the tools needed to explore this regime. For example, one of my interests is crystallization-a process of importance in both nature and industry. An especially interesting aspect of crystallization is the ability of certain molecular "poisons" to control crystallization kinetics by adsorbing to specific crystal growth faces. Such so-called kinetic inhibitors are relevant commercially (e.g., the prevention of "gelation" of diesel fuels at low temperature and of clathrate hydrate formation in natural gas pipelines), medically (e.g., the prevention of kidney stones in humans), and in nature (e.g., proteins that allow some organisms to survive subzero temperatures). Another research direction has been the measurement of the mechanical strength of materials on the nanometer scale. Understanding the mechanical properties of nanomaterials, and how these properties arise from their structure, is a prerequisite to their use in technology. These two themes intersect in the principal tool employed in my laboratory: the atomic force microscope (AFM). This use of the AFM has resulted in several collaborative projects. One example that is still in its early stages is the measurement of the adhesive properties of the acquired enamel pellicle, a thin protein layer that protects teeth from cavities and controls plaque formation.****Over the next five years, we will use the AFM to study-at the molecular scale-the mechanisms that allow certain peptides to prevent calcification responsible for kidney stones. In a second collaborative project we will use the AFM to directly measure the adhesion of specific oral bacteria to the acquired enamel pellicle. Our recent work on spider-mite silk, a natural nanomaterial produced by a common plant pest, indicated a need to develop new theoretical techniques to understand mechanical properties in the limit of very thin (<100 nm), highly elastic nanofibres. I am also interested in soft materials such as poly(vinyl alcohol) hydrogels, which have a range of applications as a biomaterial, including active wound dressings, artificial cartilage, and vascular grafts.  Since tailoring these materials to specific applications requires an understanding of their structure, we have employed a suite of techniques to study them, including small-angle neutron scattering and microrheology, which we will now extend to include dielectric spectroscopy.****Students involved in my research program will learn advanced characterization techniques, develop strong analytical skills, and benefit from a multidisciplinary research environment. This will provide them with the broad background needed to apply their training to a wide range of problems relevant to industry and medicine, thus enhancing their career opportunities.**