EIS studies of valinomycin-mediated K+ transport through supported lipid bilayers

Vallejo, Alcira Estela; Gervasi, C.A.

doi:10.1016/j.jelechem.2007.01.022

Cited by 6 publications

(9 citation statements)

References 29 publications

(32 reference statements)

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“…However, the stringent specification of a very high coverage required to use this membrane in a sensor was checked in this work through the significant change in the net ion flux across the membrane due to the incorporation of the ionophore and not due to "leaky" flux through local disruptions in the membrane. Moreover, the measured potentiometric signal dependent on the aqueous ion concentration in a Nernstian manner across two-decade change in concentration, as reported previously [27], is a clear indication that the system response is due to the ion flux through the membrane. (Fig.…”

Section: Resultssupporting

confidence: 80%

Impedance Analysis of Ion Transport Through Supported Lipid Membranes Doped with Ionophores: A New Kinetic Approach

2007

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Kinetics of facilitated ion transport through planar bilayer membranes are normally analyzed by electrical conductance methods. The additional use of electrical relaxation techniques, such as voltage jump, is necessary to evaluate individual rate constants. Although electrochemical impedance spectroscopy is recognized as the most powerful of the available electric relaxation techniques, it has rarely been used in connection with these kinetic studies. According to the new approach presented in this work, three steps were followed. First, a kinetic model was proposed that has the distinct quality of being general, i.e., it properly describes both carrier and channel mechanisms of ion transport. Second, the state equations for steady-state and for impedance experiments were derived, exhibiting the input-output representation pertaining to the model's structure. With the application of a method based on the similarity transformation approach, it was possible to check that the proposed mechanism is distinguishable, i.e., no other model with a different structure exhibits the same input-output behavior for any input as the original. Additionally, the method allowed us to check whether the proposed model is globally identifiable (i.e., whether there is a single set of fit parameters for the model) when analyzed in terms of its impedance response. Thus, our model does not represent a theoretical interpretation of the experimental impedance but rather constitutes the prerequisite to select this type of experiment in order to obtain optimal kinetic identification of the system. Finally, impedance measurements were performed and the results were fitted to the proposed theoretical model in order to obtain the kinetic parameters of the system. The successful application of this approach is exemplified with results obtained for valinomycin-K(+) in lipid bilayers supported onto gold substrates, i.e., an arrangement capable of emulating biological membranes.

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Section: Resultssupporting

confidence: 80%

Impedance Analysis of Ion Transport Through Supported Lipid Membranes Doped with Ionophores: A New Kinetic Approach

2007

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“…synthetic membranes and the proteins, usually single species, contained therein. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] More recently we have advanced the biomimetic nature of these systems to include cytoskeletal components and developed routes that allow such planar membranes to be formed from native membranes. 21 In addressing membranes containing multiple proteins it is apparent there would be significant advantage if one could also manipulate lipids and proteins within the membrane, perhaps allowing the separation of proteins (according to their charge) or allowing their concentration (and thereby permitting the application of other techniques).…”

Section: Insight Innovation Integrationmentioning

confidence: 99%

Manipulation and charge determination of proteins in photopatterned solid supported bilayers

et al. 2009

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This work demonstrates the use of deep UV micropatterned chlorotrimethylsilane (TMS) monolayers to support lipid membranes on SiO(2) surfaces. After immersing such a patterned surface into a solution containing small unilamellar vesicles of egg PC, supported bilayer lipid membranes were formed on the hydrophilic, photolyzed regions and lipid monolayer over the hydrophobic, non-photolyzed regions. A barrier between the lipid monolayer and bilayer regions served to stop charged lipids migrating between the two. This allows the system to be used to separate charged lipids or proteins by electrophoresis. Either oppositely charged fluorescence labeled lipids [Texas Red DHPE (negative charge) and D291 (positive charge)] or lipids with different charge numbers [Texas Red DHPE (one negative charge) and NBD PS (two negative charges)] can be separated. We have also studied the migration of streptavidin attached to a biotinylated lipid. Negatively charged streptavidin responds to the applied electric field by moving in the direction of electroosmotic flow, i.e. towards the negative electrode. However the direction of streptavidin movement can be controlled by altering the difference in zeta potential between that of the streptavidin (zeta(1)) and the lipid membrane (zeta(2)). If zeta(1) > zeta(2), streptavidin moves to the negative electrode, while if zeta(1) < zeta(2), streptavidin moves to the positive electrode. This balance was manipulated by adding positively charged lipid DOTAP to the membrane. After measuring the average drift velocity of streptavidin as a function of DOTAP concentration, the point where zeta(1) approximately zeta(2) was found. At this point zeta(1) was calculated to be -9.8 mV which is in good agreement with the value of -13 mV from force measurements and corresponds to a charge of -2e per streptavidin, thus demonstrating the applicability of this method for determining protein charge.

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“…As proper functioning of membrane proteins requires association with lipid bilayer and cell membrane is too complex to isolate actions of a specific protein, systems based on artificial lipid bilayer (biomimetic membrane) have been employed (Chan and Boxer, 2007;Schuster and Sleytr, 2006) to investigate the function of membrane-associated proteins, such as ionophores (Sato et al, 1998;Vallejo and Gervasi, 2007), pore-forming toxin (Bockenroth et al, 2008), receptors (Favero et al, 2005), voltage-dependent anion channel (Deniaud et al, 2007) and so on. Herein, we integrate artificial lipid bilayer with carbon nanotube devices and demonstrate that such hybrid nanoelectronic devices can be used to detect activities of membrane proteins in their native lipid environment.…”

Section: Introductionmentioning

confidence: 99%

Integrating carbon nanotubes and lipid bilayer for biosensing

Huang

Palkar.

et al. 2010

Biosensors and Bioelectronics

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EIS studies of valinomycin-mediated K+ transport through supported lipid bilayers

Cited by 6 publications

References 29 publications

Impedance Analysis of Ion Transport Through Supported Lipid Membranes Doped with Ionophores: A New Kinetic Approach

Impedance Analysis of Ion Transport Through Supported Lipid Membranes Doped with Ionophores: A New Kinetic Approach

Manipulation and charge determination of proteins in photopatterned solid supported bilayers

Integrating carbon nanotubes and lipid bilayer for biosensing

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