We have created a molecule that forms self-assembled monolayers (SAMs) on Au possessing the characteristics for inhibition of nonspecific protein adsorption, i.e., uniformly distributed, loosely-packed, conformationally mobile, hydrated ethylene oxide (EO) chains of near optimal packing densities for 6 1 EO units. SAMs of the bipodal molecule CH3O(CH2CH2O)5CH2CON(CH2CH2CH2SCOCH3)2 [nomenclature: N,N-(bis 3 -thioacetylpropyl)-3,6,9,12,15,18-hexaoxanonadecanamide, BTHA] on polycrystalline Au are described. Spectroscopic ellipsometry (SE) and reflection-absorption infrared spectroscopy data indicate BTHA SAM thickness and EO chain disorder closely match that of partially-formed monothio (EO)5-6CH3 SAMs when they exhibit maximum inhibition of protein adsorption. However, in contrast to the monothio (EO)5-6CH3 SAMs, the BTHA SAM thickness and EO chain disorder remain constant in the presence of unbound molecules due to the structurally-imposed upper limit of one EO chain per two Au occupancy sites. SE data indicate high resistance to protein adsorption for bovine serum albumin, fibrinogen, and a mixture of the two, suggesting uniform EO surface coverage on a length scale at least equal to the smallest dimension of these proteins.
Pub Type: Journals