AVS 52nd International Symposium
    Biomaterial Interfaces Monday Sessions
       Session BI-MoP

Paper BI-MoP9
Grafting of PEG-Macromonomers to Plasma Polymers Using Ceric Ion Initiation

Monday, October 31, 2005, 5:00 pm, Room Exhibit Hall C&D

Session: Biomaterial Interfaces Poster Session
Presenter: N.J. Vickers, University of Sheffield, UK
Authors: N.J. Vickers, University of Sheffield, UK
A.G. Shard, University of Sheffield, UK
S. Mac Neil, University of Sheffield, UK
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Bioadhesion, the adsorption of proteins, cells, or bacteria to a surface can be extremely detrimental to the performance of medical devices. Prevention of non-specific adsorption is therefore a key characteristic for many biomaterial applications and applying a non-fouling surface treatment can improve the performance of some medical devices. Poly(ethylene glycol) [PEG] is currently the most effective chemical modifier at reducing bioadhesion. Plasma polymers provide a thin, conformal base on which to graft. It is proposed that grafting PEG onto plasma polymers will confer non-fouling properties. Ceric ion initiation is commonly employed to graft polymers to natural polysaccharides e.g. starch. The initiation is thought to proceed through oxidation of hydroxyl groups. We have investigated ceric ion initiated grafting of PEG-macromonomers to several plasma polymers. Radio frequency glow discharge plasma polymerisation of isopropanol was carried out to obtain functional surfaces containing alcohol groups. Octadiene plasma polymer surfaces were made as a control hydrocarbon. Aqueous solutions of PEG-macromonomers and cerium ammonium nitrate were combined and plasma polymer samples introduced. Characterisation was carried out via X-ray photoelectron spectroscopy [XPS]. The influence of reagent concentration, chemical nature of the plasma polymer and grafting time were investigated. The success of ceric initiated grafting was demonstrated by the presence of a chemically shifted peak in the C1s narrow scan at 286.5eV binding energy. The intensity of this peak can be directly correlated with the amount of grafted material. Both time of reaction and concentration of initator have been shown to influence the polymer graft density, whilst the plasma polymer chemistry is of paramount importance. Currently work is underway to investigate the non-fouling properties of the PEG-grafted surfaces using protein adsorption methods.