Neutron Reflectometry Elucidates Protein Adsorption from Human Blood Serum onto PEG Brushes

Latza, Victoria M.; Rodriguez-Loureiro, Ignacio; Kiesel, Irena; Halperin, A.; Fragneto, Giovanna; Schneck, Emanuel

doi:10.1021/acs.langmuir.7b03048

Cited by 9 publications

(20 citation statements)

References 70 publications

(155 reference statements)

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“…For instance, although surface plasmon resonance (SPR) can confirm qualitatively that brushes have protein excluding properties, [8][9][10] it does not provide the concentration profile perpendicular to the surface. Furthermore, neutron reflectometry can analyze where in the brush proteins are located, 11,12 but if adsorption occurs on the solid surface it remains unknown if the kinetic barrier was insufficient or if the polymer did not successfully outcompete the protein-surface attraction. In addition, all techniques based on averaging over a planar interface will have contributions from impurities and various types of defects.…”

mentioning

confidence: 99%

“…In addition, all techniques based on averaging over a planar interface will have contributions from impurities and various types of defects. The literature is particularly inconsistent regarding potentially favorable interactions between proteins and PEG, 12 which severely complicates reaching an understanding of, for instance, the fate of PEG-modified particles in the body. 4 In this work, we provide the first conclusive evidence that a hydrophilic polymer brush can be a strong kinetic barrier for proteins by preparing PEG brushes inside different types of plasmonic nanopores.…”

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confidence: 99%

“…30 In conclusion, we have shown conclusive experimental evidence that hydrophilic polymer brushes can be extremely strong entropic barriers which prevent the passage of serum proteins, even when the thickness is only tens of nm. Despite the claims of attractive interactions between PEG and proteins, 12 the repulsive nature of the brush clearly dominates.…”

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confidence: 99%

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Polymer brushes in solid-state nanopores form an impenetrable entropic barrier for proteins

et al. 2018

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Polymer brushes are widely used to prevent the adsorption of proteins, but the mechanisms by which they operate have remained heavily debated for many decades. We show conclusive evidence that a polymer brush can be a remarkably strong kinetic barrier towards proteins by using poly(ethylene glycol) grafted to the sidewalls of pores in 30 nm thin gold films. Despite consisting of about 90% water, the free coils seal apertures up to 100 nm entirely with respect to serum protein translocation, as monitored label-free through the plasmonic activity of the nanopores. The conclusions are further supported by atomic force microscopy and fluorescence microscopy. A theoretical model indicates that the brush undergoes a morphology transition to a sealing state when the ratio between the extension and the radius of curvature is approximately 0.8. The brush-sealed pores represent a new type of ultrathin filter with potential applications in bioanalytical systems.

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Polymer brushes in solid-state nanopores form an impenetrable entropic barrier for proteins

et al. 2018

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“…As reported in the previous section, the main limitation of the slab model is the description of (vertically, along z) diffuse layers. This can be the case, among several others, of polymer brushes deposited onto surfaces [30][31][32] or of inhomogeneous systems [33], for which a description through a limited number of well defined layers might fail. As reported in the cited literature, these systems can be modeled by a combination of slabs, for the homogeneous regions (if any) of the sample, and by functional distributions, describing volume fraction profiles, for the inhomogeneous ones.…”

Section: Functional Component Groupsmentioning

confidence: 99%

Applications of neutron reflectometry in biology

Gerelli

2020

EPJ Web Conf.

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Over the last 10 years, neutron reflectometry (NR) has emerged as a powerful technique for the investigation of biologically relevant thin films. The great advantage of NR with respect to many other surface-sensitive techniques is its sub-nanometer resolution that enables structural characterizations at the molecular level. In the case of bio-relevant samples, NR is non-destructive and can be used to probe thin films at buried interfaces or enclosed in bulky sample environment equipment. Moreover, recent advances in biomolecular deutera-tion enabled new labeling strategies to highlight certain structural features and to resolve with better accuracy the location of chemically similar molecules within a thin film. In this chapter I will describe some applications of NR to bio-relevant samples and discuss some of the data analysis approaches available for biological thin films. In particular, examples on the structural characterization of biomembranes, protein films and protein-lipid interactions will be described.

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“…25 The literature contains many reports that these goals can be successfully achieved. 22,26,27 The literature also describes cases where PEG layers support protein and cell adhesion because layers are too thin 25,28 or flawed, 29,30 or because anchoring and functional groups are exposed. 21 The current work employs PEG-coating formulations and architectures described in the literature, 21,22,24 and confirmed here, to prevent protein adsorption and, in gentle flow, to avoid cell accumulation within detectible limits.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties and Concentrations of Poly(ethylene glycol) in Hydrogels and Brushes Direct the Surface Transport of Staphylococcus aureus

Kolewe

Kalasin

Shave

et al. 2018

ACS Appl. Mater. Interfaces

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Surface-associated transport of flowing bacteria, including cell rolling, is a mechanism for otherwise immobile bacteria to migrate on surfaces and could be associated with biofilm formation or the spread of infection. This work demonstrates how the moduli and/or local polymer concentration play critical roles in sustaining contact, dynamic adhesion, and transport of bacterial cells along a hydrogel or hydrated brush surface. In particular, stiffer more concentrated hydrogels and brushes maintained the greatest dynamic contact, still allowing cells to travel along the surface in flow. This study addressed how the mechanical properties, molecular architectures, and thicknesses of minimally adhesive poly(ethylene glycol) (PEG)-based coatings influence the flow-driven surface motion of Staphylococcus aureus MS2 cells. Three protein-repellant PEG-dimethylacrylate hydrogel films (~100 μm thick) and two protein-repellant PEG brushes (8–16 nm thick) were sufficiently fouling-resistant to prevent the accumulation of flowing bacteria. However, the rolling or hopping-like motions of gently flowing S. aureus cells along the surfaces were specific to the particular hydrogel or brush, distinguishing these coatings in terms of their mechanical properties (with moduli from 2 to 1300 kPa) or local PEG concentrations (in the range 10–50% PEG). On the stiffer hydrogel coatings having higher PEG concentrations, S. aureus exhibited long runs of surface rolling, 20–50 μm in length, an increased tendency of cells to repeatedly return to some surfaces after rolling and escaping, and relatively long integrated contact times. By contrast, on the softer more dilute hydrogels, bacteria tended to encounter the surface for brief periods before escaping without return. The dynamic adhesion and motion signatures of the cells on the two brushes were bracketed by those on the soft and stiff hydrogels, demonstrating that PEG coating thickness was not important in these studies where the vertically oriented surfaces minimized the impact of gravitational forces. Control studies with similarly sized poly(ethylene oxide)-coated rigid spherical microparticles, that also did not arrest on the PEG coatings, established that the bacterial skipping and rolling signatures were specific to the S. aureus cells and not simply diffusive. Dynamic adhesion of the S. aureus cells on the PEG hydrogel surfaces correlated well with quiescent 24 h adhesion studies in the literature, despite the orientation of the flow studies that eliminated the influence of gravity on bacteria-coating normal forces.

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Neutron Reflectometry Elucidates Protein Adsorption from Human Blood Serum onto PEG Brushes

Cited by 9 publications

References 70 publications

Polymer brushes in solid-state nanopores form an impenetrable entropic barrier for proteins

Polymer brushes in solid-state nanopores form an impenetrable entropic barrier for proteins

Applications of neutron reflectometry in biology

Mechanical Properties and Concentrations of Poly(ethylene glycol) in Hydrogels and Brushes Direct the Surface Transport of Staphylococcus aureus

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