Self-assembled Monolayers of Methyl 1-thiahexa(ethylene oxide) for the Inhibition of Protein Adsorption
David J. Vanderah, Gintaras Valincius, Curtis W. Meuse
Self-assembled monolayers (SAMs) of methyl 1-thiahexa(ethylene oxide) [HS(CH2CH2O)6CH3] on gold were evaluated for their inhibition of non-specific protein adsorption (NSPA). Reflection-adsorption infrared spectroscopy (RAIRS) data of the HS(CH2CH2O)6CH3 SAMs showed that the 1-thiahexa(ethylene oxide) segment adopts the well ordered 7/2 helical conformation of the folded-chain crystal (FCC) polymorph of poly(ethylene oxide) upon assembly from 95% and 100% ethanol. Less ordered SAMs of HS(CH2CH2O)6CH3 were obtained upon assembly from tetrahydrofuran (THF), which RAIRS data indicateed are mixtures of the FCC and disordered conformations. Exposure of these surfaces to bovine serum albumin (BSA) and lysozyme solutions showed that the less ordered HS(CH2CH2O)6CH3 SAMs from THF exhibit better inhibition of NSPA. Thus the inhibition of NSPA of oligo(ethylene oxide) and methoxy-capped oligo(ethylene oxide) SAM surfaces cannot be attributed to highly ordered, helical conformations.
oligo (ethylene oxides), protein adsorption, self-assembled monolayers