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

Paper BI-ThM2
Surface Modification of a Model Biomaterial by UV-Laser and/or Electron Beam Irradiation@footnote 1@

Thursday, October 28, 1999, 8:40 am, Room 613/614

Session: Biomineralization
Presenter: M.L. Dawes, Washington State University
Authors: M.L. Dawes, Washington State University
Y. Kawaguchi, Chugoku National Industrial Research Institute, Japan
S.C. Langford, Washington State University
J.T. Dickinson, Washington State University
Correspondent: Click to Email
Single crystal brushite (CaHPO@sub 4@@super .@2H@sub 2@O) is a model hydrated phosphate for studies of surface modification, etching, and biocompatible film growth by laser ablation. In this study we show that significant chemical and morphological changes are produced on such crystal surfaces by irradiation with electron and UV-laser beams. These changes are due to both photoelectronic and thermal effects, principally involving the anion, and are associated with high densities of point defects. We compare the spectroscopic and morphological changes generated by laser and electron beam irradiation as well as by thermal treatment in vacuum. All three treatments dehydrate the surface material; the resulting material forms subsurface, micron-sized platelets which can be exposed by spontaneous fracture of the surface layer. Spectroscopic evidence for reduced forms of phosphorus (primarily pyrophosphate but also elemental phosphorous) are observed on the treated material. Mass spectroscopy of laser-induced emissions from treated material show significant O@sub 2@ and PO@sub x@ emissions, consistent with this reduction. @FootnoteText@ @footnote 1@ This work is supported by the Department of Energy (DE-FG03-98ER14864) and the National Science Foundation (CMS-98-00230).