An in situ Infrared Spectroscopic Study of Glutamic Acid and of Aspartic Acid Adsorbed on TiO(2): Implications for the Biocompatibility of Titanium.

In situ ATR-IR spectroscopy has been applied to the study of glutamic (Glu) and aspartic (Asp) acid adsorbed on amorphous TiO(2) particle films. Unlike Asp, which gives evidence of one major adsorbed species, Glu yields several spectroscopically distinct structures upon adsorption to TiO(2). The pH dependence of Glu and Asp adsorption is also different, with Glu adsorbing markedly to TiO(2) at pH where electrostatic interactions between the surface and adsorbate are unfavorable. Application of the Langmuir model to adsorption isotherms yields a single binding constant for Asp and two binding constants for Glu, further supporting the evidence for different adsorbed Glu species. This is the first investigation of the molecular structure of Glu and Asp species adsorbed on amorphous TiO(2) using in situ ATR-IR spectroscopy. Copyright 2000 Academic Press.