Monolayers of derivatized poly(L-lysine)-grafted poly(ethylene glycol) on metal oxides as a class of biomolecular interfaces

We report on the design and characterization of a class of biomolecular int erfaces based on derivatized poly(L-lysine)-grafted poly(ethylene glycol) c opolymers adsorbed on negatively charged surfaces. As a model system, we sy nthesized biotin-derivatized poly(L-lysine)-grafted poly(ethylene glycol) c opolymers, PLL-9[(PEGm)((1-x)) (PEG-biotin)(x)], where x varies from 0 to 1 . Monolayers were produced on titanium dioxide substrates and characterized by x-ray photoelectron spectroscopy. The specific biorecognition propertie s of these biotinylated surfaces were investigated with the use of radiolab eled streptavidin alone and within complex protein mixtures. The PLL-g-PEG- biotin monolayers specifically capture streptavidin, even from a complex pr otein mixture, while still preventing nonspecific adsorption of other prote ins. This streptavidin layer can subsequently capture biotinylated proteins . Finally, with the use of microfluidic networks and protein arraying, we d emonstrate the potential of this class of biomolecular interfaces for appli cations based on protein patterning.