AVS 46th International Symposium
    Biomaterial Interfaces Group Thursday Sessions
       Session BI-ThM

Paper BI-ThM9
Incorporation of Dye Molecules into Calcium Oxalate Host Crystals

Thursday, October 28, 1999, 11:00 am, Room 613/614

Session: Biomineralization
Presenter: L.A. Touryan, University of Washington
Authors: L.A. Touryan, University of Washington
R.W. Gurney, University of Washington
M.J. Lochhead, University of New Hampshire
B. Kahr, University of Washington
V. Vogel, University of Washington
Correspondent: Click to Email
Biological systems direct inorganic mineral synthesis and subsequent composite growth via molecular interactions between macromolecules and mineral phases. However, describing the relationship between the organic and inorganic molecules and their interactive functions at the molecular level remains difficult. Exactly how additives orient within host lattices is not known, as biomineral crystals accommodate their presence but they do not give rise to sufficient intensity in x-ray diffraction studies. Nevertheless, it is this integration of large biomolecules into much smaller unit cells that profoundly changes the materials properties of biominerals and make their synthetic recreation desirable for novel material design and the enhanced biocompatibility of biomedical implants. Here we discuss the use of sensitive optical techniques, in conjunction with modeling, to determine the spatial orientation of organic additives within the host lattice of a calcium biomineral. We have found that common aryl-carbonium dye molecules such as eosin and fluorescein incorporate into the lattice structure of calcium oxalate, the primary biomineral of kidney stones. These dyes tend to incorporate along the fastest growing crystal planes, and can be detected through fluorescence microspectroscopy. We have measured the intensity of polarized fluorescence on two well-developed crystal faces, calculated dichroic ratios, and used the data to model the direct orientation of the transition dipole moments of organic dyes that incorporate within the inorganic host lattice.