Protein Resistance of PEG-Functionalized Dendronized Surfaces: Effect of PEG Molecular Weight and Dendron Generation

Dendronized surfaces were prepared by chemisorption of poly(ethylene glycol) monothiol (HS-PEG₆₅₀-OH) onto gold-coated silicon wafers followed by functionalization of the PEG terminal OH group with aliphatic polyester dendrons, generation 1−4, using divergent dendron growth. PEG monomethyl ether (PEG-OMe) chains of various molecular weight (MW) were covalently attached to the peripheral hydroxyl groups of the dendronized surfaces via EDC coupling and investigated for protein adsorption. Protein adsorption studies were carried out using fibrinogen (Fg) and lysozyme (Lys) as model proteins from phosphate buffered saline (PBS) (Fg, Lys) and plasma (Fg). In the first part of this study, the effect of functionalization of the peripheral hydroxyl groups with PEG-OMe oligomers (M_n = 350 Da) on protein adsorption was investigated. Results showed that adsorption of both Fg and Lys was reduced when dendronized surfaces were grafted with PEG-OMe oligomers. To investigate the effect of molecular weight on protein adsorption, PEG-OMe chains of greater length (750, 2000, and 5000 Da) were coupled to first generation dendronized surfaces (Au-G1(OH)). Results showed that protein adsorption decreased with increasing PEG-OMe MW up to 2000 Da. To further investigate the effect of dendron generation on protein resistance, dendronized surfaces of generation 1−4 were coupled with PEG₂₀₀₀-acid. Subsequent protein studies showed a decrease in Fg and Lys adsorption with increasing dendron generation.