Electrokinetic analysis of poly(ethylene glycol) coating chemistry

Characterization of surface coatings formed with poly(ethylene glycol) (PEG) or related hydrophilic, neutral polymers can be achieved by means of free solution capillary electrophoresis. The method is nondestructive, relatively fast, mechanically simple, is performed in aqueous solution, and can be automated. Mathematical modeling provides estimates of surface density, pK of surface chemical groups and coating thickness for PEG coatings and for organosilane and other treatments used to activate surfaces prior to PEG grafting. This paper reviews recent studies by the authors related to coating quartz surfaces with PEG. Variables studied include surface activation, polymer molecular weight, linking chemistry, and hydrolytic and oxidative stability. The method improves understanding of PEG on surfaces, and provides methods for obtaining stable PEG coatings of controlled density. Chemistry for tethering molecules via PEG linkers is also discussed.