Fabrication and electromechanical characterization of freestanding asymmetric membranes

Liu, Paige; Zabala-Ferrera, Oscar; Beltramo, Peter J.

doi:10.1016/j.bpj.2021.02.036

Cited by 14 publications

(19 citation statements)

References 69 publications

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“…By using this protocol, we investigate the influence of voltage polarity and NP charge on the NP–membrane interaction . Also, we simulate, as a first approximation, the conditions of living cells where the concerted interplay of ion channels generates dynamic changes in both membrane potential (∼ ±100 mV) , and ionic fluxes. , …”

Section: Resultsmentioning

confidence: 99%

“…By using this protocol, we investigate the influence of voltage polarity and NP charge on the NP−membrane interaction. 25 Also, we simulate, as a first approximation, the conditions of living cells where the concerted interplay of ion channels generates dynamic changes in both membrane potential (∼ ±100 mV) 89,90 and ionic fluxes. 91,92 Figure 4 shows the representative traces of the ion currents induced by PS-COOH (A,B), PS (C,D), and PS-NH 2 (E,F) displaying a variety of current levels that fluctuate with time.…”

Section: ■ Introductionmentioning

confidence: 99%

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Surface-Functionalized Polystyrene Nanoparticles Alter the Transmembrane Potential via Ion-Selective Pores Maintaining Global Bilayer Integrity

et al. 2022

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Although nanoplastics have well-known toxic effects toward the environment and living organisms, their molecular toxicity mechanisms, including the nature of nanoparticle–cell membrane interactions, are still under investigation. Here, we employ dynamic light scattering, quartz crystal microbalance with dissipation monitoring, and electrophysiology to investigate the interaction between polystyrene nanoparticles (PS NPs) and phospholipid membranes. Our results show that PS NPs adsorb onto lipid bilayers creating soft inhomogeneous films that include disordered defects. PS NPs form an integral part of the generated channels so that the surface functionalization and charge of the NP determine the pore conductive properties. The large difference in size between the NP diameter and the lipid bilayer thickness (∼60 vs ∼5 nm) suggests a particular and complex lipid–NP assembly that is able to maintain overall membrane integrity. In view of this, we suggest that NP-induced toxicity in cells could operate in more subtle ways than membrane disintegration, such as inducing lipid reorganization and transmembrane ionic fluxes that disrupt the membrane potential.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Surface-Functionalized Polystyrene Nanoparticles Alter the Transmembrane Potential via Ion-Selective Pores Maintaining Global Bilayer Integrity

et al. 2022

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“…Recent pore-spanning membrane platforms involve lipid bilayers supported over multiple pores [ 80 ], as well as thin-film pressure balances, which are combined with electrophysiology for precise characterization of large area model biomembranes (LAMBs). These systems have been presented by Beltramo et al, providing control over membrane tension with varying solvents [ 72 , 81 ] and demonstrating asymmetric membrane formation [ 82 ].…”

Section: Model Membranes: Manufactures and Resulting Propertiesmentioning

confidence: 99%

Characterizing the Structure and Interactions of Model Lipid Membranes Using Electrophysiology

El-Beyrouthy

Freeman

2021

Membranes

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The cell membrane is a protective barrier whose configuration determines the exchange both between intracellular and extracellular regions and within the cell itself. Consequently, characterizing membrane properties and interactions is essential for advancements in topics such as limiting nanoparticle cytotoxicity. Characterization is often accomplished by recreating model membranes that approximate the structure of cellular membranes in a controlled environment, formed using self-assembly principles. The selected method for membrane creation influences the properties of the membrane assembly, including their response to electric fields used for characterizing transmembrane exchanges. When these self-assembled model membranes are combined with electrophysiology, it is possible to exploit their non-physiological mechanics to enable additional measurements of membrane interactions and phenomena. This review describes several common model membranes including liposomes, pore-spanning membranes, solid supported membranes, and emulsion-based membranes, emphasizing their varying structure due to the selected mode of production. Next, electrophysiology techniques that exploit these structures are discussed, including conductance measurements, electrowetting and electrocompression analysis, and electroimpedance spectroscopy. The focus of this review is linking each membrane assembly technique to the properties of the resulting membrane, discussing how these properties enable alternative electrophysiological approaches to measuring membrane characteristics and interactions.

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“…Apart from hybrid lipids, there are other molecules that influence bilayer structure and properties to a great extent. Cell membranes are in contact with a wide variety of molecules, such as oily lipid droplets, , and because some methods to form a model bilayer necessitate the use of a solvent for the lipids (such as black lipid membranes and droplet–interface bilayers), − oil molecules have been the subject of numerous studies. − The biological motivation for studying the effect of oil molecules on membrane properties includes identifying the thermodynamic driving force for oily lipid droplet budding from existing membranes and examining the interplay between membrane thickness and protein function. , Experimentally, the requirement to use oil solvents in numerous artificial membrane techniques necessitates an understanding of how the oil is affecting membrane properties to properly interpret results. As a result, attention has focused on how this residual oil affects bilayer structure and phase separation temperatures. ,,, An important result of these studies was that phase separation temperatures are increased when residual oil is present in the bilayer.…”

Section: Introductionmentioning

confidence: 99%

“…By doing so, we turn the presence of oil, which is usually considered to be a disadvantage, into a possible advantage to create model bilayers where composition regulates domain size, making the effects readily studied by standard fluorescence microscopy. We use a thin film balance, which is a modification of the Montal–Mueller technique, which allows for precise control of the disjoining pressure and tension in the film to produce large-area model biomembranes (LAMBs). − LAMBs are planar as well as free-standing and have an area of up to 1 mm 2 , thereby facilitating detailed studies of phase separation kinetics because many domains can be visualized by fluorescence microscopy as the temperature is modulated. We adopt a stringent protocol where the phase separation is induced by a relatively slow temperature quench, and the membrane tension can be controlled by modulating the pressure in the film, ensuring bilayer stability.…”

Section: Introductionmentioning

confidence: 99%

Domain Size Regulation in Phospholipid Model Membranes Using Oil Molecules and Hybrid Lipids

et al. 2022

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The formation of domains in multicomponent lipid mixtures has been suggested to play a role in moderating signal transduction in cells. Understanding how domain size may be regulated by both hybrid lipid molecules and impurities is important for understanding real biological processes; at the same time, developing model systems where domain size can be regulated is crucial to enable systematic studies of domain formation kinetics and thermodynamics.Here, we perform a model study of the effects of oil molecules, which swell the bilayer, and line-active hybrid phospholipids using a thermally induced liquid−solid phase separation in planar, free-standing lipid bilayers consisting of DOPC and DPPC (1,2-dioleoyl-sn-glycero-3phosphocholine and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, respectively). The experiments show that the kinetics of domain growth are significantly affected by the type and molecular structure of the oil (squalene, hexadecane, or decane), with the main contributing factors being the degree of swelling of the bilayer and the changes in line tension induced by the different oils, with smaller domains resulting from systems with smaller values of the line tension. POPC (1-palmitoyl-sn-2-oleoyl-glycero-3phosphocholine), on the other hand, acts as a line-active hybrid lipid, reducing the domain size when added in small amounts and slowing down domain coarsening. Finally, we show that despite the regulation of domain size by both methods, the phase transition temperature is influenced by the presence of oil molecules but not significantly by the presence of hybrid lipids. Overall, our results show how to regulate domain size in binary membrane model systems, over a wide range of length scales, by incorporating oil molecules and hybrid lipids.

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Fabrication and electromechanical characterization of freestanding asymmetric membranes

Cited by 14 publications

References 69 publications

Surface-Functionalized Polystyrene Nanoparticles Alter the Transmembrane Potential via Ion-Selective Pores Maintaining Global Bilayer Integrity

Surface-Functionalized Polystyrene Nanoparticles Alter the Transmembrane Potential via Ion-Selective Pores Maintaining Global Bilayer Integrity

Characterizing the Structure and Interactions of Model Lipid Membranes Using Electrophysiology

Domain Size Regulation in Phospholipid Model Membranes Using Oil Molecules and Hybrid Lipids

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