Surface energy of phospholipid bilayers and the correlation to their hydration

Klapper, Yvonne; Vrânceanu, Marcel; Ishitsuka, Yuji; Evans, David A.; Scheider, Dominic; Nienhaus, G. Ulrich; Leneweit, Gero

doi:10.1016/j.jcis.2012.09.027

Cited by 8 publications

(7 citation statements)

References 42 publications

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“…18,37,38 Such layers are very efficient in preventing protein adsorption, especially when using long PEG chains. If PEG polymers are covalently attached to a surface, 18,39,40 the grafting density is limited by the PEG chain entropy, which drives PEG into a random coil shape, thereby hindering a close spacing of anchoring groups on the surface. 37,41 Proteins may penetrate less dense PEG layers, reside in voids, 42 and even approach and interact with the underlying reactive surfaces.…”

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confidence: 99%

Surface Functionalization of Nanoparticles with Polyethylene Glycol: Effects on Protein Adsorption and Cellular Uptake

et al. 2015

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Here we have investigated the effect of enshrouding polymer-coated nanoparticles (NPs) with polyethylene glycol (PEG) on the adsorption of proteins and uptake by cultured cells. PEG was covalently linked to the polymer surface to the maximal grafting density achievable under our experimental conditions. Changes in the effective hydrodynamic radius of the NPs upon adsorption of human serum albumin (HSA) and fibrinogen (FIB) were measured in situ using fluorescence correlation spectroscopy. For NPs without a PEG shell, a thickness increase of around 3 nm, corresponding to HSA monolayer adsorption, was measured at high HSA concentration. Only 50% of this value was found for NPs with PEGylated surfaces. While the size increase clearly reveals formation of a protein corona also for PEGylated NPs, fluorescence lifetime measurements and quenching experiments suggest that the adsorbed HSA molecules are buried within the PEG shell. For FIB adsorption onto PEGylated NPs, even less change in NP diameter was observed. In vitro uptake of the NPs by 3T3 fibroblasts was reduced to around 10% upon PEGylation with PEG chains of 10 kDa. Thus, even though the PEG coatings did not completely prevent protein adsorption, the PEGylated NPs still displayed a pronounced reduction of cellular uptake with respect to bare NPs, which is to be expected if the adsorbed proteins are not exposed on the NP surface.

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confidence: 99%

Surface Functionalization of Nanoparticles with Polyethylene Glycol: Effects on Protein Adsorption and Cellular Uptake

et al. 2015

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“…Under liquid-film, the interfacial energies of SF-Lys[PEG] surfaces and SF-Lys surfaces as measured with the functionalized sharp AFM tip were 15.1 ± 1.6 mJ/m 2 and 6.4 ± 0.52 mJ/m 2 , respectively, while the same values measured with the functionalized colloidal AFM probe were much lower, 0.24 ± 0.08 mJ/m 2 and 0.16 ± 0.03 mJ/m 2 (Figure a). Additionally, the interfacial strength was much higher for SF-Lys[PEG] surfaces due to the presence of the loose loopy PEG topmost layer, which contributes to energy dissipation during the disjoining process …”

Section: Resultsmentioning

confidence: 99%

“…Additionally, the interfacial strength was much higher for SF-Lys[PEG] surfaces due to the presence of the loose loopy PEG topmost layer, which contributes to energy dissipation during the disjoining process. 84 A significant reduction of the measured values for colloidal tips can be related to the lower contribution of the uneven surface topography with grainy texture to the contact areas (fraction of microns) that results in overvaluation of the true contact area under very low local pressure and minute silk surface deformations with colloidal probes. 85−87 Another possibility is that the effective tip contact area was overestimated using the DMT model due to the effect of substrate interactions.…”

Section: ■ Introductionmentioning

confidence: 99%

Interfacial Shear Strength and Adhesive Behavior of Silk Ionomer Surfaces

et al. 2017

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The interfacial shear strength between different layers in multilayered structures of layer-by-layer (LbL) microcapsules is a crucial mechanical property to ensure their robustness. In this work, we investigated the interfacial shear strength of modified silk fibroin ionomers utilized in LbL shells, an ionic-cationic pair with complementary ionic pairing, (SF)-poly-l-glutamic acid (Glu) and SF-poly-l-lysine (Lys), and a complementary pair with partially screened Coulombic interactions due to the presence of poly(ethylene glycol) (PEG) segments and SF-Glu/SF-Lys[PEG] pair. Shearing and adhesive behavior between these silk ionomer surfaces in the swollen state were probed at different spatial scales and pressure ranges by using functionalized atomic force microscopy (AFM) tips as well as functionalized colloidal probes. The results show that both approaches were consistent in analyzing the interfacial shear strength of LbL silk ionomers at different spatial scales from a nanoscale to a fraction of a micron. Surprisingly, the interfacial shear strength between SF-Glu and SF-Lys[PEG] pair with partially screened ionic pairing was greater than the interfacial shear strength of the SF-Glu and SF-Lys pair with a high density of complementary ionic groups. The difference in interfacial shear strength and adhesive strength is suggested to be predominantly facilitated by the interlayer hydrogen bonding of complementary amino acids and overlap of highly swollen PEG segments.

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“…For the estimation of the lipid mixing rate, we monitored the fluorescence increase over time of one of the dyes when it invades the GUV initially labeled with the other fluorophore. For the data analysis, our approach is based on a methodology commonly used in fluorescence recovery after photobleaching (FRAP) studies. ,− First, the fluorescence intensity was normalized to the maximum intensity reached after fusion. The data were then fitted to an exponential function f( x ) = A [1 – exp(− t /τ)], where A is the change in fluorescence, t is the time passed since the lipids begin to mix, and τ is the time constant.…”

Section: Methodsmentioning

confidence: 99%

Biomimetic Curvature and Tension-Driven Membrane Fusion Induced by Silica Nanoparticles

Perez

Beales

2021

Langmuir

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Fusion events in living cells are intricate phenomena that require the coordinate action of multicomponent protein complexes. However, simpler synthetic tools to control membrane fusion in artificial cells are highly desirable. Native membrane fusion machinery mediates fusion, driving a delicate balance of membrane curvature and tension between two closely apposed membranes. Here, we show that silica nanoparticles (SiO2 NPs) at a size close to the cross-over between tension-driven and curvature-driven interaction regimes initiate efficient fusion of biomimetic model membranes. Fusion efficiency and mechanisms are studied by Förster resonance energy transfer and confocal fluorescence microscopy. SiO2 NPs induce a slight increase in lipid packing likely to increase the lateral tension of the membrane. We observe a connection between membrane tension and fusion efficiency. Finally, real-time confocal fluorescence microscopy reveals three distinct mechanistic pathways for membrane fusion. SiO2 NPs show significant potential for inclusion in the synthetic biology toolkit for membrane remodeling and fusion in artificial cells.

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Surface energy of phospholipid bilayers and the correlation to their hydration

Cited by 8 publications

References 42 publications

Surface Functionalization of Nanoparticles with Polyethylene Glycol: Effects on Protein Adsorption and Cellular Uptake

Surface Functionalization of Nanoparticles with Polyethylene Glycol: Effects on Protein Adsorption and Cellular Uptake

Interfacial Shear Strength and Adhesive Behavior of Silk Ionomer Surfaces

Biomimetic Curvature and Tension-Driven Membrane Fusion Induced by Silica Nanoparticles

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