Peptide functionalized poly(L-lysine)-g-poly(ethylene glycol) on titanium: resistance to protein adsorption in full heparinized human blood plasma

The graft copolymer poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) and its RGD- and RDG-functionalized derivs. (PLL-g-PEG/PEG-peptide) were assembled from aq. solns. on titanium (oxide) surfaces. The polymers were characterized by NMR in order to det. quant. the grafting ratio, g (Lys monomer units/PEG side chains), and the fraction of the PEG side chains carrying the terminal peptide group. The titanium surfaces modified with the polymeric monomol. adlayers were exposed to full heparinized blood plasma. The adsorbed masses were measured by in situ ellipsometry. The different PLL-g-PEG-coated surfaces showed, within the detection limit of the ellipsometric technique, no statistically significant protein adsorption during exposure to plasma for 30 min at 22 DegC or 37 DegC, whereas clean, uncoated titanium surfaces adsorbed approx. 350 ng/cm2 of plasma proteins. The high degree of resistance of the PEGylated surface to non-specific adsorption makes peptide-modified PLL-g-PEG a useful candidate for the surface modification of biomedical devices such as implants that are capable of eliciting specific interactions with integrin-type cell receptors even in the presence of full blood plasma. The results refer to short-term blood plasma exposure that cannot be extrapolated a priori to long-term clin. performance. [on SciFinder (R)]