Oligo(ethylene oxide) self-assembled monolayers with self-limiting packing densities for the inhibition of nonspecific protein adsorption.
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. SAMs of the bipodal molecule CH(3)O(CH(2)CH(2)O)(5)CH(2)CON(CH(2)CH(2)CH(2)SCOCH(3))(2) [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 that BTHA SAM thickness and EO chain disorder closely match that of partially formed monothio-(EO)(5-6)CH(3) SAMs when they exhibit maximum inhibition of protein adsorption. However, in contrast to the monothio-(EO)(5-6)CH(3) SAMs, the BTHA SAM thickness and EO chain disorder remain constant in the presence of unbound molecules because of 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.
Vanderah
David J
DJ
Biochemical Science Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, USA. david.vanderah@nist.gov
Vierling
Ryan J
RJ
Walker
Marlon L
ML
D000327:Adsorption; D000818:Animals; D002417:Cattle; D005027:Ethylene Oxide / Q000737:chemistry*; D005340:Fibrinogen / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D015394:Molecular Structure; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D013057:Spectrum Analysis; D013379:Substrate Specificity
D012710:Serum Albumin, Bovine; D006046:Gold; D005340:Fibrinogen; D005027:Ethylene Oxide