Preparation of Mixed Self-Assembled Monolayers (SAMs) That Resist Adsorption of Proteins Using the Reaction of Amines with a SAM That Presents Interchain Carboxylic Anhydride Groups

Abstract

This paper describes a procedure for preparing mixed self-assembled monolayers (mixed SAMs) on gold that resist the nonspecific adsorption of proteins from solution. This method was tested using α-amino derivatives of ω-hydroxy- and ω-methoxy-oligo(ethylene glycols): H2N(CH2CH2O)nCH3 and H2N(CH2CH2O)nH (n = 3, 6). Mixed SAMs were prepared by allowing these amines to react with a SAM presenting interchain carboxylic anhydride groups. The resistance of the resulting surfaces to adsorption of several proteinscarbonic anhydrase (EC 4.2.1.1), ribonuclease A (EC 3.1.27.5), lysozyme (EC 3.2.1.17), and fibrinogenwas examined using surface plasmon resonance (SPR) spectroscopy. These mixed SAMs resist the nonspecific adsorption of proteins approximately as effectively as single-component SAMs prepared using the conventional method involving chemisorption of oligo(ethylene glycol)-terminated alkanethiols on gold. Characterization of the mixed SAM that presents a 1:1 mixture of −OCNH(CH2CH2O)6CH3 and CO2H/CO2- group...