Oligo(ethylene glycol) (OEG) and poly(ethylene glycol) (PEG) monolayers have biotechnological applications such as biosensing, bio-compatibility (e.g. of implants) and in supporting model membranes. It has been found that these monolayers are resistant to irreversible protein adsorption, although the underlying physicochemical mechanisms for this are still under discussion. We have studied the protein density profile at the solid/liquid interface in order to obtain information about the interactions between OEG layers and proteins. Neutron reflection results reveal an oscillatory density profile for the protein solution immediately above the OEG layer. This indicates that the proteins reach the proximity of the OEG layer, but are prevented from adsorbing irreversibly, by, for instance, a strongly bound water layer. The net effect of salt was also studied and appears to be small, although charges may play a more subtle role in the complex balance of forces within this intricate system.
MWA Skoda, JRP Webster (ISIS), F Schreiber (Tübingen University, Germany), RMJ Jacobs (Oxford University), M Wolff (ILL, France), R Dahint, D Schwendel, M Grunze (Heidelberg University, Germany)
Contact: Dr MWA Skoda, Maximilian.Skoda@stfc.ac.uk
Further reading: MWA Skoda et al. Langmuir 25 (2009) 4056