Coverage of Si substrates by self-assembling monolayers and multilayers as measured by IR, wettability and X-ray diffraction

Pomerantz, M.; Segmüller, Armin; Netzer, Lucy; Sagiv, Jacob

doi:10.1016/0040-6090(85)90466-3

Cited by 167 publications

(108 citation statements)

References 10 publications

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“…Their precise common value z SK ∼ 58 Å can be rationalized in the following way. Starting from the solid surface at z = 0, the dense OTS layer, including silane and alkyl portions has a thickness of d 1 ∼ 25 Å, as reported in previous reflectometry studies (27,28). The thickness of the first (inner) monolayer of SGS with its C 16 /C 17 alkyl chains and the saccharide headgroup can be estimated as d 1 ∼ 20-25 Å.…”

Section: Resultsmentioning

confidence: 67%

Atom-scale depth localization of biologically important chemical elements in molecular layers

Schneck

Scoppola

Drnec

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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In nature, biomolecules are often organized as functional thin layers in interfacial architectures, the most prominent examples being biological membranes. Biomolecular layers play also important roles in context with biotechnological surfaces, for instance, when they are the result of adsorption processes. For the understanding of many biological or biotechnologically relevant phenomena, detailed structural insight into the involved biomolecular layers is required. Here, we use standing-wave X-ray fluorescence (SWXF) to localize chemical elements in solid-supported lipid and protein layers with near-Ångstrom precision. The technique complements traditional specular reflectometry experiments that merely yield the layers' global density profiles. While earlier work mostly focused on relatively heavy elements, typically metal ions, we show that it is also possible to determine the position of the comparatively light elements S and P, which are found in the most abundant classes of biomolecules and are therefore particularly important. With that, we overcome the need of artificial heavy atom labels, the main obstacle to a broader application of high-resolution SWXF in the fields of biology and soft matter. This work may thus constitute the basis for the label-free, element-specific structural investigation of complex biomolecular layers and biological surfaces.surfaces | interfaces | lipid membranes | protein adsorption | X-ray scattering N anometric biomolecular layers in interfacial geometries are key components of biological matter. Biological membranes, for example, are 2D molecular structures composed mainly of lipids and proteins in an aqueous environment (1, 2). Interfacial biomolecular layers are also important from a biotechnological perspective, where surfaces are often designed to selectively promote or prevent the adsorption of bio(macro)molecules from solution (3). To investigate the diverse behavior of biomolecules at interfaces, well-defined planar model systems of biological and biotechnologically relevant interfaces have been established (4, 5). Processes involving biomolecules at interfaces are typically accompanied by a spatial reorganization of molecules, changes in molecular conformations, or the adsorption of molecules in a chemically heterogeneous environment (6). Structural insight on the nanometer scale is therefore of paramount importance.X-ray and neutron scattering are uniquely suited for the structural investigation of biomolecular systems. Specular reflectometry reveals matter density profiles perpendicular to a planar interface. However, it is generally difficult to elucidate molecular conformations and elemental distributions from such "global" density profiles. In contrast, standing-wave X-ray fluorescence (SWXF) allows determining element-specific density profiles across an interface. The SWXF technique is based on the elementcharacteristic fluorescence induced by a standing X-ray wave. The latter is formed by interference of the incident and reflected waves and its shape depends o...

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Section: Resultsmentioning

confidence: 67%

Atom-scale depth localization of biologically important chemical elements in molecular layers

Schneck

Scoppola

Drnec

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…One of the interesting compounds useful for MEMS lubrication is n-octadecyltrichlorosilane (OTS), n-C 18 H 37 SiC 13 which gives complete coverage of smooth surfaces of n-type silicon by densely packed monolayers formed by chemisorption of silane compounds incorporated in solutions [55]. Sliding experiments with glass spheres and p-type smooth silicon wafers coated with n-C 18 H 37 SiC 13 , n-C 11 H 23 SiC 13 (UTS), and n-C 6 F 13 CH 2 CH 2 SiC 13 (FTS) [55] have shown insignificant wear and relatively low friction for OTS and UTS monolayers (friction coefficients 0.07 and 0.09, respectively), and significantly higher friction (friction coefficient 0.16) and wear for FTS monolayers, presumably due to incomplete coverage of silicon surface by the thinner (1 nm) FTS monolayers.…”

Section: Lubrication and Modification Of Mems Surfacesmentioning

confidence: 99%

Control tribological and mechanical properties of MEMS surfaces. Part 1: critical review

Rymuza

1999

Microsystem Technologies

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“…These molecules react faster with the silanol groups of the surface and also due to self-assembling character of the long alkyl chains, as result of the lateral van der Waal forces between the alky chains, are able to form densely packed highly ordered monomolecular assemblies with solidstate-like properties. 25 Unfortunately, the use of APS analogues with long alkyl chains such as (17-aminoheptadecil)-trimethoxysilane, does not give rise to well ordered monolayers. 26 This is very likely due to the hydrogen bond formation between the amine group and silanol surface.…”

Section: Short Survey In Chemical Modification Of Surfacesmentioning

confidence: 99%

New Developments for the Site-Specific Attachment of Protein to Surfaces

Camarero

2006

Biophys. Rev. Lett.

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Protein immobilization on surfaces is of great importance in numerous applications in biology and biophysics. The key for the success of all these applications relies on the immobilization technique employed to attach the protein to the corresponding surface. Protein immobilization can be based on covalent or noncovalent interaction of the molecule with the surface. Noncovalent interactions include hydrophobic interactions, hydrogen bonding, van der Waals forces, electrostatic forces, or physical adsorption. However, since these interactions are weak, the molecules can get denatured or dislodged, thus causing loss of signal. They also result in random attachment of the protein to the surface. Site-specific covalent attachment of proteins onto surfaces, on the other hand, leads to molecules being arranged in a definite, orderly fashion and uses spacers and linkers to help minimize steric hindrances between the protein surface. This work reviews in detail some of the methods most commonly used as well as the latest developments for the site-specific covalent attachment of protein to solid surfaces.

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Coverage of Si substrates by self-assembling monolayers and multilayers as measured by IR, wettability and X-ray diffraction

Cited by 167 publications

References 10 publications

Atom-scale depth localization of biologically important chemical elements in molecular layers

Atom-scale depth localization of biologically important chemical elements in molecular layers

Control tribological and mechanical properties of MEMS surfaces. Part 1: critical review

New Developments for the Site-Specific Attachment of Protein to Surfaces

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