Optimizing Cell−Surface Interactions by Photografting of Poly(ethylene glycol)

A new general approach for improving polymer substratum biocompatibility is proposed. In a first example, polysulfone (PSf) film was modified by covalent end-on grafting of poly(ethylene glycol) (PEG) (2, 5, and 10 kDa) using well-defined, photoreactive α-4-azidobenzoyl β-methoxy PEG conjugates (ABMPEG). After adsorption from aqueous solution, ABMPEG was photografted under wet conditions onto PSf, where the degree of surface functionalization could be controlled through the applied ABMPEG concentration during adsorption. Attained surface characteristics, after changing systematically ABMPEG concentration, molecular weight, and the ratio of binary ABMPEG mixtures, were monitored by air−water contact angles (CA, captive bubble method) and partially also by X-ray photon spectroscopy (XPS). For ABMPEG 10 kDa adsorption kinetics and grafting efficiency as a function of applied concentration were evaluated by both CAs and fibronectin (FN) adsorption (in situ ellipsometry) to surfaces modified at different degre...