AVS 53rd International Symposium
    Surface Science Thursday Sessions
       Session SS1-ThM

Paper SS1-ThM3
Probing of the Surface Chemistry and Binding Modes of DL-proline on TiO@sub2@(110) Single Crystal Surface: A Study via High Resolution X-ray Photoelectron Spectroscopy and Temperature Programmed Desorption

Thursday, November 16, 2006, 8:40 am, Room 2002

Session: Reactivity of Oxide Surfaces I
Presenter: G.J. Fleming, The University of Auckland, New Zealand
Authors: G.J. Fleming, The University of Auckland, New Zealand
K. Adib, Brookhaven National Laboratory
J.A. Rodriguez, Brookhaven National Laboratory
M.A. Barteau, University of Delaware
H. Idriss, The University of Auckland, New Zealand
Correspondent: Click to Email
The use of titanium metal as a biomaterial has become common place in modern medicine due to its desirable mechanical properties and the relative chemical inertness.@footnote 1,2@ This has lead to the use of titanium in many medical applications ranging from hip replacements to aiding in the healing of fractures that occur in teeth and bones. When the titanium implant is placed inside the body's aqueous environment an oxidation process occurs, where an oxide layer forms in the range of approximately 10-100 nm thick. This layer is crucial since it prevents the Ti metal from further reacting with the biological molecules. However, it is the nature of the interaction of the bio-molecule with this thin TiO@sub2@ surface which ultimately determines the molecules final conformation. In this work we discus the surface chemistry and the nature of the interactions of DL-proline, a major constituent of the main structural protein in the body collagen I, on both oxidised and reduced TiO@sub2@(110) single crystal surfaces using High Resolution X-Ray Photoelectron Spectroscopy (HR-XPS) and Temperature Programmed Desorption (TPD). Upon adsorption on to the oxidised surface at 300 K, the N 1s spectrum revealed that proline is present as two distinct species: molecular (-NH-) and zwitterionic proline (-NH@sub2@@super+@-). Via the use of variable temperature XPS, the zwitterionic species was found to be only weakly adsorbed and removed form the surface by approximately 600 K. On the reduced surface, an increase in the amount of zwitterionic species adsorbed to the surface was found and can be attributed to the loss of bridging oxygen atoms from the (110) surface. TPD experiments show a very complex reaction pathways, in particular on the reduced surfaces, similar in nature to previous studies performed on the TiO@sub2@(011) surface.@footnote 3@. @FootnoteText@@footnote 1@F.H Jones, Surf. Sci. Rep. 2001 42, 75. @footnote 2@B. Kasemo, Surf. Sci. 2002, 500, 656 @footnote 3@G.J. Fleming and H. Idriss, Langmuir, 2004, 20, 7540.