Deep UV Photochemistry of Chemisorbed Monolayers: Patterned Coplanar Molecular Assemblies

Dulcey, C. S.; Georger, Jacque H.; Krauthamer, Victor; Stenger, David A.; Fare, Thomas L.; Calvert, Jeffrey M.

doi:10.1126/science.2020853

Cited by 485 publications

(366 citation statements)

References 12 publications

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“…Understanding the photoreactivity of SAMs is important for optimizing photoresist patterning processes involving SAMs. [7][8][9][10][11] As the feature sizes in lithography continue to scale down, there is an increasing demand on the resist films in terms of thickness and structural uniformity. [12][13][14][15] SAMs are an attractive candidate for nanoscale resists due to their molecular thickness and well-defined structure on nanometer length scales, which in principle should enable nanometer resolution in pattern transfer.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of UV Photoreactivity of Alkylsiloxane Self-Assembled Monolayers

McArthur

Borguet

2005

J. Phys. Chem. B

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A molecular level understanding of the photoreactivity of self-assembled monolayers (SAMs) becomes increasingly important as the spatial resolution starts to be limited by the size of the resist and the spatial extent of the photochemical reactions in photoresist micropatterning. To this end, a number of surface characterization techniques were combined to understand the reactive agents, reactive sites, kinetics, and reaction pathways in the UV photoreactivity of octadecylsiloxane (ODS) SAMs. Quantitative analysis of our results provides evidence that ground state atomic oxygen is the primary reactive agent for the UV degradation of ODS SAMs. UV degradation, which follows zero-order kinetics, results in the scission of alkyl chains instead of the siloxane headgroups. Our results suggest that the top of the ODS SAMs is the preferential reactive site. Using a novel, highly surface sensitive technique, fluorescence labeling of surface species, we identified the presence of submonolayer quantities chemical functional groups formed by the UV degradation. These groups are intermediates in a proposed mechanism based on hydrogen abstraction.

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Section: Introductionmentioning

confidence: 99%

Mechanism of UV Photoreactivity of Alkylsiloxane Self-Assembled Monolayers

McArthur

Borguet

2005

J. Phys. Chem. B

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“…photochemical modification of uniform, thin organic films [7][8][9]; 2. spatially-controlled radio frequency glow discharge treatment of polymer surfaces [10,11];…”

Section: Introductionmentioning

confidence: 99%

Chemical pattern on silica surface prepared by UV irradiation of 3-mercaptopropyltriethoxy silane layer: surface characterization and fibrinogen adsorption

Liu¹,

Hlady²

1996

Colloids and Surfaces B: Biointerfaces

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A flat silica surface modified with 3-mercaptopropyltriethoxy silane (MTS) was patterned using UV irradiation and a custom-designed mask. The irradiated surface was characterized by X-ray photoelectron spectroscopy (XPS), scanning force microscopy (SFM) and water contact angle measurements. The XPS S2p spectra indicated that the UV treatment resulted in the oxidation of MTS sulfur. The optimal UV irradiation dose for patterning, estimated from the XPS S2p binding energy shifts and water contact angles of irradiated surfaces, was 4.8 J cm −2 at 270 nm. The surface patterns were visualized by total internal reflection fluorescence microscopy, while exposing the pattern to a solution of acridine orange, by water vapor condensation, and by SFM lateral force imaging in dilute electrolyte solution. The adhesion SFM measurements revealed the adhesion force only on the areas which were not UV-irradiated. The adsorption of fluoresceinlabeled fibrinogen (FITC-Fgn) from dilute buffer solution also produced visual information on the pattern. The kinetics of FITC-Fgn adsorption onto the oxidized and unoxidized MTS-silica surfaces from dilute protein solution proceeded with identical initial adsorption rates. The steadystate FITC-Fgn adsorption was twice as large on the unoxidized MTS-silica than on the oxidized MTS-silica surface.

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“…29,30 Pioneering work has been done by the Parikh laboratory to pattern solid supported lipid bilayers using deep UV radiation. [31][32][33][34] Additionally, deep UV radiation had been employed to pattern organosilane monolayers, 35,36 polysaccharides, 37 and S-layer proteins. 38 In this paper, we extend this idea to patterning sacrificial adsorbed protein layers at the liquid/solid interface.…”

mentioning

confidence: 99%

Multiplexing Ligand−Receptor Binding Measurements by Chemically Patterning Microfluidic Channels

2008

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A method has been designed for patterning supported phospholipid bilayers (SLBs) on planar substrates and inside microfluidic channels. To do this, bovine serum albumin (BSA) monolayers were formed via adsorption at the liquid/solid interface. Next, this interfacial protein film was selectively patterned by using deep UV lithography. Subsequently, SLBs could be deposited in the patterned locations by vesicle fusion. By cycling through this process several times, spatially addressed bilayer arrays could be formed with intervening protein molecules serving as twodimensional corrals. By employing this method, phospholipid bilayers containing various concentrations of ganglioside GM1 were addressed along the length of individual microfluidic channels. Therefore, the binding of GM1 with pentameric cholera toxin B (CTB) subunits could be probed. A seven-channel microfluidic device was fabricated for this purpose. Each channel was simultaneously patterned with four chemically distinct SLBs containing 0, 0.2, 0.5, and 2.0 mol % GM1, respectively. Varying concentrations of CTB were then introduced into each of the channels. With the use of total internal reflection fluorescence microscopy, it was possible to simultaneously abstract multiple equilibrium dissociation constants as a function of ligand density for the CTB-GM1 system in a single shot.Multivalent ligand-receptor interactions are ubiquitous on cell surfaces. They have a wide variety of consequences including the modulation of equilibrium dissociation constants, high receptor selectivity, and receptor clustering. 1 Multivalency can also play a direct role in signal transduction processes. 2 Examination of the underlying thermodynamics of ligandreceptor binding may lead to a greater understanding of its biological role and could provide insight into biomedical applications involving inhibitory drug design. 1,3,4 Unfortunately, high-throughput, low-protein consumption assays are not presently well enough developed in this field to afford rapid, systematic studies of binding data at two-dimensionally fluid bilayer interfaces. 5 In previous work it has been demonstrated that microfluidic devices can be designed for measuring binding affinities in multivalent systems. [5][6][7][8][9][10][11][12][13][14] In our previous setup, ligands were incorporated into supported lipid bilayers (SLBs) coated on the walls and floors of polydimethylsiloxane/glass microchannels. Linear arrays of channels were then monitored by total internal reflection fluorescence microscopy (TIRFM) 15 to obtain equilibrium dissociation constants in one-shot assays. This could be done by using the same surface chemistry in each microchannel while varying the solution concentration of the aqueous proteins. Such a setup made these assays relatively rapid, afforded high accuracy, and used only a few microliters of protein solution. Nevertheless, such platforms could be markedly improved by measuring multiple binding constants with various membrane chemistries simultaneously. This could be achie...

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Deep UV Photochemistry of Chemisorbed Monolayers: Patterned Coplanar Molecular Assemblies

Cited by 485 publications

References 12 publications

Mechanism of UV Photoreactivity of Alkylsiloxane Self-Assembled Monolayers

Mechanism of UV Photoreactivity of Alkylsiloxane Self-Assembled Monolayers

Chemical pattern on silica surface prepared by UV irradiation of 3-mercaptopropyltriethoxy silane layer: surface characterization and fibrinogen adsorption

Multiplexing Ligand−Receptor Binding Measurements by Chemically Patterning Microfluidic Channels

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