AVS 55th International Symposium & Exhibition
    Biomaterial Interfaces Wednesday Sessions
       Session BI-WeA

Paper BI-WeA3
A Novel Approach to XPS Characterisation of ‘Click’ Surface Chemistry, More Information Less Damage

Wednesday, October 22, 2008, 2:20 pm, Room 202

Session: Quantitative Analysis of Biointerfaces
Presenter: T.S. Nunney, Thermo Fisher Scientific, UK
Authors: T.S. Nunney, Thermo Fisher Scientific, UK
R.G. White, Thermo Fisher Scientific, UK
N.B. Larsen, Technical University of Denmark
T.S. Hansen, Technical University of Denmark
A.E. Daugaard, Technical University of Denmark
S. Hvilsted, Technical University of Denmark
Correspondent: Click to Email

‘Click’ chemistry is increasingly used for chemical surface engineering of polymer devices to be used in biological and medical applications. Advantages of ‘click’ chemistry include mild reaction conditions, i.e. aqueous environment at room temperature, and high chemical specificity of the coupling. We recently demonstrated surface engineering of ultrathin electrically conductive polymer films by ‘clicking’ organic functional units that control wettability, protein adhesion, or fluorescence, all functions of major relevance to biomedical applications. The most commonly used click reaction is based on the coupling of organic azides to alkynes. This is also the basis of our recently reported functional monomer, azide modified 3,4-ethylenedioxythiophene, for conducting polymer films (PEDOT-N3) reactive towards alkyne functionalized molecular species. The ability of X-ray photoelectron spectroscopy (XPS) to provide quantitative chemical state information makes it ideal for the investigation of the resultant clicked surface chemistry. In the example above, differences in the XPS binding energy for the azide and triazole nitrogens serve as a useful method to determine if the click reaction has completed successfully. It is known, however, that degradation of the azide chemistry during XPS measurement process can significantly obscure the result. In this paper we will discuss methods for minimisation of the measurement-induced chemical degradation. These methods rely on a number of hardware and software features which have recently become available on modern XPS instrumentation. The methods described require the layers to be uniform so that the data can be collected as a map, thus reducing the X-ray and electron flux density during the measurement. Deconvolution routines will be shown to facilitate the rapid chemical state mapping of patterned variants of these surfaces.