- LOPEZ, GP and BIEBUYCK, HA and HARTER, R. and KUMAR, A. and WHITESIDES, GM, FABRICATION AND IMAGING OF 2-DIMENSIONAL PATTERNS OF PROTEINS ADSORBED ON SELF-ASSEMBLED MONOLAYERS BY SCANNING ELECTRON-MICROSCOPY,
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 115 no. 23
pp. 10774--10781 .
(last updated on 2010/02/08)
This paper describes methods for controlling both the concentration and spatial distribution of proteins adsorbed onto patterned, self-assembled monolayers (SAMs). Patterned SAMs were formed by the serial chemisorption of two or more omega-functionalized alkanethiols (HS(CH2)(n)R) on gold. Several techniques (microwriting, micromachining, stamping, and UV microlithography) were used to fabricate the patterned SAMs. The most useful systems of patterned SAMs for studying the adsorption of proteins are those in which spatially-defined areas that resist protein adsorption arc formed from oligo(ethylene glycol)-terminated thiols (e.g., R = (OCH2CH2)6OH) and other areas that allow protein adsorption are formed from thiols terminated by nonpolar (R = CH3) and ionic (R = CO2-, PO3H-, 2-imidazolo) groups. Scanning electron microscopy (SEM) allows characterization of patterns of proteins adsorbed on SAMs of alkanethiolates. The adsorbed proteins, when correctly prepared, form layers that appear to be homogeneous by SEM. When the protein layers are prepared differently, images obtained by SEM clearly show heterogeneity and defects in the layer of adsorbed proteins. The ability to assay the uniformity of coverage of surfaces by adsorbed proteins using SEM will be useful in studies involving protein adsorption.