Synthesis and Characterization of Amine-Terminated Self-Assembled Monolayers Containing Diethylene Glycol Linkages

Abstract

A new synthesis of amino di(ethylene glycol)-terminated alkylthiol 1 (AEG2) is described. This precursor, made via a Mitsunobu synthesis, is designed to form self-assembled monolayers (SAMs) on gold, which allow direct coupling of biomolecules. The AEG2 SAMs have been characterized by ellipsometry, X-ray photoelectron spectroscopy, and advancing water contact angle and by their interactions with proteins. Ellipsometry and X-ray photoelectron spectroscopy indicate that the AEG2 precursor forms well-ordered SAMs of the expected thickness and composition. Contact angle measurements indicate that the AEG2 SAMs are slightly more hydrophobic than SAMs of a di(ethylene glycol)-terminated alkylthiol (EG2). Interestingly, the AEG2 SAMs do not resist the nonspecific adsorption of fibrinogen, pyruvate kinase, or bovine serum albumin but do resist adsorption of streptavidin. Mixed SAMs of 20:80 mol % AEG2/EG2 composition resist the adsorption of pyruvate kinase and bovine serum albumin.

Preparation, characterization, resistance to protein adsorption, and specific avidin–biotin binding of poly(amidoamine) dendrimers functionalized with oligo(ethylene glycol) on gold

“…T e of the EG n -PAMAM layers on MUA SAMs was 21, 22, and 23 Å for n = 3, 4, and 6, respectively, indicating an increase of 5, 6, and 7 Å upon attachment of the corresponding EG n to the dendrimer surfaces. The increase in T e is smaller than the calculated length of an EG n chain [29,[54][55][56], indicating that only some of the peripheral free amines of the dendrimers are accessible to react with the NHS-EG n derivatives. θ a/r of the EG n -dendrimer surfaces was 41 • /27 • , 42 • /27 • , and 43 • /29 • for n = 3, 4, and 6, respectively.…”

Synthesis and characterization of tri(ethylene oxide)-attached poly(amidoamine) dendrimer layers on gold

“…On the contrary to these requirements, the terminal amines of the EO 3 -dendrimer layers would be positively charged under the reaction condition of pH 7.4, hence acting as a hydrogen bond donor, which is attributed to diminished resistance of the EO 3 -dendrimer layers to protein adsorption. This explanation might be supported from the result by Chirakul et al regarding the nonspecific adsorption of proteins onto the amine-terminated SAM surface [46]. They prepared and surface characterized the mixed SAMs consisting of di(ethylene glycol)-terminated thiolates and amine-terminated, di(ethylene glycol)-incorporated thiolates, preferable to covalent coupling of a wide variety of biomolecules.…”

Electrochemical soft lithography of an 1,7-octadiene monolayer covalently linked to hydrogen-terminated silicon using scanning probe microscopy

“…In recent years, lithographic techniques for the surface modification of inorganic and organic surfaces have been developed for application to sensing [1], data memory [2,3], single molecule electronic, and biological systems [4][5][6]. In particular, the nano and micropatterning of organic monolayers have attracted attention for application to biological systems in which proteins or DNA are fixed [4].…”