Micrometer and Nanometer Scale Photopatterning of Proteins on Glass Surfaces by Photo-degradation of Films Formed from Oligo(Ethylene Glycol) Terminated Silanes

Abstract

Exposure of films formed by the adsorption of oligo(ethylene glycol) (OEG) functionalized trichlorosilanes on glass to UV light from a frequency-doubled argon ion laser (244 nm) causes photodegradation of the OEG chain. Although the rate of degradation is substantially slower than for monolayers of OEG terminated thiolates on gold, it is nevertheless possible to form micrometer-scale patterns by elective adsorption of streptavidin to exposed regions. A low density of aldehyde functional groups is produced, and this enables derivatization with nitrilotriacetic acid via an amine linker. Complexation with nickel enables the site-specific immobilization of histidine-tagged yellow and green fluorescent proteins. Nanometer-scale patterns may be fabricated using a Lloyd's mirror interferometer, with a sample and mirror set at right angles to each other. At low exposures, partial degradation of the OEG chains does not remove the protein-resistance of the surface, even though friction force microscopy reveals the formation of patterns. At an exposure of ca. 18 J cm(-2), the modified regions became adhesive to proteins in a narrow region ca. 30 nm (λ/8) wide. As the exposure is increased further the lines quickly broaden to ca. 90 nm. Adjustment of the angle between the sample and mirror enables the fabrication of lines of His-tagged green fluorescent protein at a period of 340 nm that could be resolved using a confocal microscope.

X-ray-induced degradation of OEG-terminated SAMs on silica surfaces during XPS characterization

“…). In any case, we did not observe the appearing of new peaks that would suggest the formation of new functional groups at the surface, as could be observed by others in different conditions …”

“…In any case, we did not observe the appearing of new peaks that would suggest the formation of new functional groups at the surface, as could be observed by others in different conditions. [18] Therefore, vacuum and low-energy electrons from the flood gun alone may be ruled out as the causes for the degradation.…”

“…OEG‐terminated SAMs are especially relevant in the field of biosensors and biotechnology because these layers inhibit non‐specific adsorption of proteins . Degradation of OEG‐terminated SAMs on gold, silicon, and silica has been demonstrated under ultraviolet or e‐beam radiation in different conditions . In these cases, oxidative processes from environmental oxygen are presented as the main cause for the degradation.…”

“…[6][7][8][9][10][11][12] Degradation of OEG-terminated SAMs on gold, silicon, and silica has been demonstrated under ultraviolet or e-beam radiation in different conditions. [13][14][15][16][17][18][19] In these cases, oxidative processes from environmental oxygen are presented as the main cause for the degradation. Furthermore, and closer to the subject matter of this paper, OEG SAMs on gold have been found to be degraded under X-ray photoelectron spectroscopy (XPS) characterization.…”

A Simple Method for Patterning Nanoparticles on Planar Surfaces

“…Poly(ethylene glycol) deposited on titanium oxide using alkane phosphate as an anchoring group demonstrated good protein resistance. However, the use of alkane phosphate as an anchoring group showed poor stability [16]. erefore, in this work, the use of silane as an anchoring group is preferred because of its stability due to the formation of two bonds between the molecules and an additional bond formed with the surface [2].…”