Monitoring protein binding to phospholipid monolayers using electrochemical impedance spectroscopy

Weiss, Sophie A.; Millner, Paul A.; Nelson, Andrew

doi:10.1016/j.electacta.2005.05.045

Cited by 13 publications

(15 citation statements)

References 40 publications

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“…Electrochemical impedance spectroscopy (EIS) is a noninvasive yet extremely sensitive method of studying interactions at the lipid interface . In this work, EIS is applied to corroborate the interactions of the DOPC assemblies with SiO 2 particles and to gain further insight into the mechanisms on the molecular level.…”

Section: Resultsmentioning

confidence: 99%

“…Electrochemical impedance spectroscopy (EIS) is a noninvasive yet extremely sensitive method of studying interactions at the lipid interface. 39 In this work, EIS is applied to corroborate the interactions of the DOPC assemblies with SiO 2 particles and to gain further insight into the mechanisms on the molecular level. In this classical model of a DOPC monolayer supported on a Hg electrode, the configuration of the assembled phospholipids can be varied by altering the applied electric field (Figure SI-1).…”

Section: Np−biomembrane Interactions On Supportedmentioning

confidence: 99%

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Freezing or Wrapping: The Role of Particle Size in the Mechanism of Nanoparticle–Biomembrane Interaction

2012

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Understanding the interactions between nanoparticles (NPs) and biological matter is a high-priority research area because of the importance of elucidating the physical mechanisms underlying the interactions leading to NP potential toxicity as well as NP viability as therapeutic vectors in nanomedicine. Here, we use two model membrane systems, giant unilamellar vesicles (GUVs) and supported monolayers, to demonstrate the competition between adhesion and elastic energy at the nanobio interface, leading to different mechanisms of NP-membrane interaction relating to NP size. Small NPs (18 nm) cause a "freeze effect" of otherwise fluid phospholipids, significantly decreasing the phospholipid lateral mobility. The release of tension through stress-induced fracture mechanics results in a single microsize hole in the GUVs after interaction. Large particles (>78 nm) promote membrane wrapping, which leads to increased lipid lateral mobility and the eventual collapse of the vesicles. Electrochemical impedance spectroscopy on the supported monolayer model confirms that differently sized NPs interact differently with the phospholipids in close proximity to the electrode during the lipid desorption process. The time scale of these processes is in accordance with the proposed NP/GUV interaction mechanism.

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Section: Resultsmentioning

confidence: 99%

Section: Np−biomembrane Interactions On Supportedmentioning

confidence: 99%

Freezing or Wrapping: The Role of Particle Size in the Mechanism of Nanoparticle–Biomembrane Interaction

2012

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“…Generally, the low-frequency relaxations observed in impedance measurements on supported layers of biologically derived materials have been attributed to MaxwellÀWagner effects, charge-carrier movement, and counterion relaxation. 17 More specifically, the low frequency elements in this DOPC monolayer system indicate the modification of the structural properties of the monolayer, 17,21,24,28 arising from the adsorption/intercalation/penetration of polymer onto and into the lipid monolayer. It is worth noting that the extent of alterations in the complex capacitance plots is correlated to the monolayer activities of the individual polymers, that is, PP-75 > PA-1 > PLP, in agreement with the results obtained from ACV and RCV.…”

Section: Ph-and Concentration-dependentmentioning

confidence: 98%

“…19,20 Therefore, the modifications of the monolayer caused by the active compounds can be simultaneously monitored electrochemically in a well controlled manner. This system has been successfully employed in the study of protein binding, 21 antibiotic/biomembrane interaction, 22À24 ion channel function, 25 and peptide/biomembrane interaction, 26À28 with exceptional sensitivity, accuracy, and reproducibility. Recently, this supported phospholipid/Hg system has been improved by replacing the traditional hanging Hg drop electrode (HMDE) with a modernized chip based device.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Substituent Grafting on the Interaction of pH-Responsive Polymers with Phospholipid Monolayers

et al. 2011

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pH-responsive amphiphilic polymers with suitable graftings have demonstrated highly efficient cell membrane activity and hence are promising applicants for drug-delivery. Grafting the hydrophobic amino acid l-phenylalanine and the hydrophilic methoxy poly(ethylene glycol) amine onto the pendant carboxylic acid moieties of a linear polyamide, poly(l-lysine isophthalamide), can effectively modify the amphiphilicity and conformation of the amphiphilic polymers. Here, the interactions of these polymers with phospholipid monolayers adsorbed on mercury (Hg) electrodes have been studied. AC voltammetry (ACV), rapid cyclic voltammetry (RCV), and electrochemical impedance spectroscopy (EIS) have been applied to monitor phospholipid monolayer associations with different polymer concentrations under different pH values. The polymers interact reversibly with the monolayer shown by altering the monolayer capacitance and inhibiting the phospholipid reorientation in electric field. Polymer grafting enhances the pH-mediated conformational change of the polymers which in turn increases their phospholipid monolayer activity. The most significant monolayer interactions have been observed with the polymer grafted with hydrophobic l-phenylalanine. A low level of PEGylation of the backbone also increases the monolayer activity. The polymer/DOPC interactions have been represented with an impedance model, which takes account of the interaction giving rise to an increase in monolayer capacitance and inhomogeneity and a Debye type dielectric relaxation. The extent of penetration of the polymers into the monolayer is inversely related to the electrical resistance they give rise to during the Debye relaxation. The cell membrane activities of these amphiphilic polymers have been successfully mirrored in this supported DOPC monolayer system, isolating the key parameters for biomembrane activities and giving insight into the mechanism of the interactions. The conclusions from this study provide strategic directions in material design catering to different requirements in biomedical applications.

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“…15b) showed that it was essential to add a proportion of PEGylated dioleoylphosphatidylethanolamine (DOPE) to the DOPC bilayer to suppress non-specific binding. 52 In such cases a balance has to be struck between suppression of non-specific binding and the need for strong binding and in this respect the length of the tether between the anchor and the biotin proves to be important. 53 As well as binding antibodies to bilayers or vesicles to microbubbles, the (biotin)-(avidin)-(biotin) couple can also be used to bind bilayers (for example vesicles) to all sorts of different surfaces.…”

Section: Uses Of Specific Protein-binding Derivatives (9 10 and Relat...mentioning

confidence: 99%

Cholesterol-based anchors and tethers for phospholipid bilayers and for model biological membranes

2010

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This review covers the range of cholesterol-based anchors and tethers and the ways in which they are being used. These cholesterol conjugates provide us with a very flexible 'tool-box' that can be used to tether phospholipid bilayers to surfaces, to join bilayers together (bilayer-to-bilayer, bilayer-to-vesicle, vesicle-to-vesicle, etc.) or to anchor molecules, biomolecules, macromolecules or particulate species to the surface of the bilayer. Model biomembranes tethered to a solid support provide a stable platform for addressing membrane components in vitro using force field and spectroscopic methods and since these membranes generally remain fluid and retain much of their biological activity, solid-supported membranes can also be use to study aspects of membrane biology and biochemistry. Potential medical applications are developing out of our ability to anchor 'markers' and antibodies to phospholipid vesicles. Compared to anchors in which the anchoring group is a phospholipid (or phospholipid-like) moiety, cholesterol-based anchors are generally easier to make and purify but the anchoring is less strong and this can be an issue when the 'payload' is large and water-soluble. In the case of nucleic acid functionalised systems this problem has been addressed by anchoring each oligonucleotide through two cholesteryl end-groups.

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Monitoring protein binding to phospholipid monolayers using electrochemical impedance spectroscopy

Cited by 13 publications

References 40 publications

Freezing or Wrapping: The Role of Particle Size in the Mechanism of Nanoparticle–Biomembrane Interaction

Freezing or Wrapping: The Role of Particle Size in the Mechanism of Nanoparticle–Biomembrane Interaction

The Effects of Substituent Grafting on the Interaction of pH-Responsive Polymers with Phospholipid Monolayers

Cholesterol-based anchors and tethers for phospholipid bilayers and for model biological membranes

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