Metals, Silicates and Phosphates in Nanobiotechnology: From Nanoscale Interfaces to Applications
Prof. Hendrik Heinz (Dept. Polymer Engineering, University of Akron, USA)

Metal nanostructures, silica, and apatites play a major role as therapeutics and natural constituents in humans, mammals, and marine bioorganisms for skeletal stability. The interactions of mineral precursors and crystallites with water, buffered solutions, and biological molecules such as structural proteins play a major role for the assembly of highly durable and stable composites. One of the major challenges for controlled biomaterial designs and treatments of diseases such as osteoporosis is better understanding of the underlying mineral surfaces and interfaces in contact with organic molecules and polyelectrolytes. Such understanding has been difficult to achieve using scattering, imaging, spectroscopy, and many other experimental techniques, yet new molecular modeling developments make very quantitative and verifiable analyses possible. We describe how the explicit consideration of key chemical aspects in force field models provides parameters that function as a ‘code’ to describe bulk and surface properties of metals, silicates, and phosphates on the 1 to 100 nm length scale. The explicit consideration of the surface chemistry of silica as a function of pH and particle size, for example, reveals major changes in cation density and affinity of specific peptides in quantitative agreement with measurements of zeta potentials and adsorption isotherms. Also, the nanostructure of hydroxyapatite and its major facets varies strongly with pH and shows very different surface definition and binding mechanisms of proteins and osteoporosis drugs that have been monitored using molecular simulation in conjunction with combinatorial screening, NMR spectroscopy, and other characterization. A wealth of information in atomic resolution is becoming accessible by such computer-aided models in conjunction with synthesis and characterization that begins to unravel the mystery of biomineralization and accelerates the discovery of new materials.