Poly[ethylene glycol] (PEG) brushes are reputed for their ability to prevent undesired protein adsorption to material surfaces exposed to biological fluids. Protein adsorption to biomedical surfaces is a major issue of this technology because it can lead to harmful foreign body reactions. However, numerous cases where the PEB brush approach failed have been reported and further investigation of the underlying molecular mechanisms is required. Here, we performed experiments to characterize the adsorption of proteins from blood serum and of two types of anti-PEG antibodies to poly(ethylene glycol) (PEG) brushes grafted to planar phospholipid surfaces.In order to obtain protein and PEG concentration profiles as a function of the altitude, we use neutron reflectometry (NR). The measurements yield volume fraction profiles of lipid head groups, PEG, and adsorbed proteins at sub-nanometer resolution. For whole human blood serum the reflectivity curves show significant primary adsorption into the lipid head group region and suggest the presence of a low amount of ternary adsorption at the brush periphery. In context with anti-PEG antibodies we obtained qualitatively different results for antibodies binding specifically to the PEG end points (endbinders) and to the backbone (backbonebinders) of the polymer. For endbinders the adsorbed amount of antibodies increases with brush grafting density, whereas backbonebinders exhibit a non-monotonic behavior. The results may constitute the basis for future applications of PEG brushes with enhanced biocompatibility.

Neutron reflectometry reveals structural aspects of blood protein and antibody adsorption to polymer brushes

256th National Meeting (2018)

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