Neutron reflectometry from poly (ethylene-glycol) brushes binding anti-PEG antibodies: Evidence of ternary adsorption

Schneck, Emanuel; Berts, Ida; Halperin, A.; Daillant, Jean; Fragneto, Giovanna

doi:10.1016/j.biomaterials.2014.12.041

Cited by 44 publications

(104 citation statements)

References 71 publications

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“…Several scenarios with similar overall layer thicknesses may occur in principle. When deposited onto hydrophobic substrates in water, the used DSPC/PEG-lipid mixtures form dense lipid monolayers displaying a highly hydrated PEG brush on top of the hydrophilic headgroups (24). One may thus expect a similar architecture also on the solid surface, with a PEG layer between the Al oxide surface and the lipid monolayer.…”

Section: Resultsmentioning

confidence: 99%

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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: 99%

“…However, this approach is only sensitive to the outer protein shape and not applicable to proteins adsorbed to soft interfaces (24). In contrast, SWXF can equally probe rigid and soft interfaces and due to its element specificity has the potential to yield a comprehensive picture of protein configurations.…”

Section: Resultsmentioning

confidence: 99%

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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“…145 NR and SE were also used complementarily to assess the mass of antibody immobilized at different concentrations. 144 Schneck et al 146 used NR to confirm the orientation of anti-(polyethylene glycol) (anti-PEG) antibodies immobilized to PEG polymer brushes of varying their grafting density. They noted that increased grafting density caused the distance between the two Fab regions to decrease and overall orients the antibodies such that the Fc region faced away from the PEG brush substrate into the bulk solution.…”

Section: E Neutron Reflectometrymentioning

confidence: 99%

Orientation and characterization of immobilized antibodies for improved immunoassays (Review)

et al. 2017

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Orientation of surface immobilized capture proteins, such as antibodies, plays a critical role in the performance of immunoassays. The sensitivity of immunodiagnostic procedures is dependent on presentation of the antibody, with optimum performance requiring the antigen binding sites be directed toward the solution phase. This review describes the most recent methods for oriented antibody immobilization and the characterization techniques employed for investigation of the antibody state. The introduction describes the importance of oriented antibodies for maximizing biosensor capabilities. Methods for improving antibody binding are discussed, including surface modification and design (with sections on surface treatments, three-dimensional substrates, self-assembled monolayers, and molecular imprinting), covalent attachment (including targeting amine, carboxyl, thiol and carbohydrates, as well as “click” chemistries), and (bio)affinity techniques (with sections on material binding peptides, biotin-streptavidin interaction, DNA directed immobilization, Protein A and G, Fc binding peptides, aptamers, and metal affinity). Characterization techniques for investigating antibody orientation are discussed, including x-ray photoelectron spectroscopy, spectroscopic ellipsometry, dual polarization interferometry, neutron reflectometry, atomic force microscopy, and time-of-flight secondary-ion mass spectrometry. Future perspectives and recommendations are offered in conclusion.

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“…[48][49][50][51][52][53][54][55][56][57][58][59] In neutron reflectometry, selective deuteration is commonly used to enhance the SLD contrast between different chemical components and thus to better discriminate between their interfacial distributions. The shape of the reflectivity curve R(q z ) encodes the interfacial SLD profile, so that the latter can be reconstructed.…”

Section: Structural Investigationsmentioning

confidence: 99%

“…The obtained SLD profiles can then be interpreted in terms of interfacial distributions of chemical components, based on their known characteristic electron or nuclear densities. [48][49][50][51][52][53][54][55][56][57][58][59] In neutron reflectometry, selective deuteration is commonly used to enhance the SLD contrast between different chemical components and thus to better discriminate between their interfacial distributions. With X-rays, direct sensitivity to the distribution of chemical elements can further be achieved by exploiting the q z -dependent characteristic X-ray fluorescence emitted by the elements of interest.…”

Section: Structural Investigationsmentioning

confidence: 99%

The Interaction between Soft Interfaces: Forces and Structural Aspects

Schneck

2016

Adv Materials Inter

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Soft interfaces constituted by two-dimensional molecular layers play important roles in numerous technological applications and are major components of all biological matter, for example in the form of biomembranes. The mutual interaction between such interfaces often crucially influences their function as well as the structural organization of the entities they form. The forces acting between two soft interfaces in liquids not only depend on their chemical properties, like charge density or hydrophilicity. They are often also closely connected to the structural response of the interfaces to their interaction, for instance in terms of molecular conformations or ion distributions. This interplay renders the description of the interaction between soft or chemically complex interfaces challenging. In the present article, various experimental and theoretical approaches to the study of interacting soft interfaces are reviewed with a focus on structural aspects

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Neutron reflectometry from poly (ethylene-glycol) brushes binding anti-PEG antibodies: Evidence of ternary adsorption

Cited by 44 publications

References 71 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

Orientation and characterization of immobilized antibodies for improved immunoassays (Review)

The Interaction between Soft Interfaces: Forces and Structural Aspects

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