Fast kinetics of thiolic self-assembled monolayer adsorption on gold: modeling and confirmation by protein binding

This study presents an improved kinetics for the formation of self-assembled monolayers (SAMs) of thiols on gold substrates. Based on predictions of a computational model developed to study the SAM growth kinetics, SAMs of 11-mercaptoinic acid and 1-octanethiol were successfully formed for the first time within 15 min by incubation of planar gold chips in a 10 mM solution of thiols in pure ethanol. The performance of this new rapid SAM formation protocol is compared to the conventional 24 h incubation protocol by evaluating the binding capacity of a fluorescent-labeled antibody to the SAM samples prepared using both protocols. Tetramethylrhodamine conjugated polyclonal goat γ-globulin (IgG) was bound to all SAMs previously modified with 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide (EDC) to improve antibody immobilization. Resulting binding density of the fast SAM was evaluated using epifluorescence and atomic force microscopy (AFM) and found to be comparable with reported values in the literature using conventional 24 h protocols.