| AVS 55th International Symposium & Exhibition | |
| Biological, Organic, and Soft Materials Focus Topic | Friday Sessions |
| Session BO+SS+AS-FrM |
| Session: | Self Assembled Ultrathin Organic Interfaces |
| Presenter: | B. Malisova, ETH Zurich, Switzerland |
| Authors: | B. Malisova, ETH Zurich, Switzerland K. Gademann, EPFL Lausanne, Switzerland S. Zuercher, ETH Zurich, Switzerland S. Tosatti, ETH Zurich, Switzerland M. Textor, ETH Zurich, Switzerland |
| Correspondent: | Click to Email |
In recent works, L-3,4-dihydroxyphenylalanine (DOPA), a catechol which is found in mussel adhesive proteins (MAPs), served as basis for poly(ethylene glycol) (PEG) ultra thin coatings capable of rendering surfaces non-fouling,1 i.e. resistant to non-specific protein adsorption and capable of withstand formation of biofilm by microorganisms.2 However, it was found that the negative charge of DOPA at physiological pH where most metal oxide surfaces are negatively charged reduces adsorption due to electrostatic repulsion effects unless at least three residues per PEG chain are used.3 We have been able to overcome this problem by synthesizing a new positively charged catechol derivative (anacat)4 based on the iron chelator anachelin which was evolutionarily developed by cyanobacteria to bind Fe(III). Incorporation of an additional positive charge resulted in a stable, protein-resistant, non-fouling coating of TiO2.5 In order to further study the effect of the charge of binding groups on the adlayer formation process as well as the effect of acidity of catecholic –OH groups, 5 different catechol binding feet were synthesized and coupled to PEG chains. Adsorption and stability properties together with the abilities to resist protein adsorption are analyzed as function of different adsorption parameters (pH, substrate type, salt concentration and temperature) by Ellipsometry (ELM) and X-Ray Photoelectron Spectroscopy (XPS). Current results suggest that the charge of the binding group, which should be opposite to the one of the substrate, as well as the difference between adsorption pH and the isoelectric point of the substrate are important parameters for all investigated molecules. Final goal of the present work is the development of a general model that explains the binding mechanism of catechols onto metal oxide substrates as function of the binding group acidity.
1 Gunawan, R. et al. Langmuir 2007, 23, (21), 10635-10643.
2 Hall-Stoodley, L. et al. Nature Reviews Microbiology 2004, 2, (2), 95-108.
3 Dalsin, J. et al. Langmuir 2005, 21, (2), 640-646.
4 Gademann, K. et al. Angew. Chem. Int. Ed. 2004, 43, (25), 3327-3329.
5 Zurcher, S. et al. JACS 2006, 128, (4), 1064-1065.