AVS 50th International Symposium
    Biomaterial Interfaces Monday Sessions
       Session BI-MoA

Invited Paper BI-MoA1
Towards the Prevention of Protein Adsorption, and Bacterial and Cell Adhesion by Optimised Surface Modification

Monday, November 3, 2003, 2:00 pm, Room 307

Session: Non-fouling Surfaces and Biolubrication
Presenter: P. Kingshott, Risoe National Lab, Denmark
Authors: P. Kingshott, Risoe National Lab, Denmark
J. Wei, Risoe National Lab, Denmark
H. Thissen, CSIRO Molecular Science, Australia
N. Gadegaard, Univ. of Glasgow, UK
D. Selmeczi, Risoe National Lab, Denmark
L. Gram, Technical Univ. of Denmark, Denmark
D. Bagge-Ravn, Technical Univ. of Denmark, Denmark
N.B. Larsen, Risoe National Lab, Denmark
H.J. Griesser, University of South Australia
Correspondent: Click to Email
A non-fouling surface is still elusive since problems such as bacterial colonisation on medical devices and food processing equipment, and failure of implants caused by clotting and foreign body reactions are still existent. Surface modification with PEG or PEO is the most effective way of reducing protein adsorption, and bacterial and cell adhesion (also called bio-adhesion). The best reports show that protein adsorption can be reduced to a fraction of the uncoated surface or even prevented. However, so far reductions in bacterial adhesion by PEG surfaces have only been marginally successful (up to 1 or 2 orders of magnitude). Why is this the case? Can surfaces that prevent protein adsorption also prevent bacterial and cell attachment? Can theoretical predictions of a non-fouling surface ever be put into practice by design of the perfect surface? In order to answer these questions it is necessary to be able to generate stable PEG layers with sufficiently high graft density and uniformity to provide the optimal steric repulsive barrier against bio-adhesion. In addition, to make the claim that a surface is non-fouling depends on one being able to detect protein adsorption below the threshold where no subsequent events can occur (such as bacterial adhesion). In this presentation some of these issues will be discussed. Surface modification based on plasma polymerisation and wet chemical methods are used to provide reactive groups for PEG grafting, confirmed by surface derivatisation reactions and surface analysis including XPS and ToF-SIMS. PEGs are grafted at their lower critical solution temperature (LCST) for maximal surface coverage. In addition, highly sensitive and specific surface mass spectrometry analysis (i.e. ToF-SIMS and surface-MALDI) is shown to be both very useful at detecting ultra-low levels of protein on the best PEG surfaces. Furthermore, the ability of PEG surfaces to prevent protein adsorption is heavily dependent on the size and type of protein.