Current bursts in lipid bilayers initiated by colloidal quantum dots

Ramachandran, Sujatha; Kumar, George L.; Blick, Robert H.; Weide, Daniel W. van der

doi:10.1063/1.1862752

Cited by 16 publications

(12 citation statements)

References 11 publications

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“…The only previous electrophysiological studies, to our knowledge, show that also CdSe quantum dots of 3À15 nm diameter cause current bursts of up to 800 pA (8 nS) in DOPC-containing bilayers and channel-like current spikes of up to 30 pA (0.6 nS) in more rigid bilayers of diphytanoyl phosphatidylcholine. 26,27 Additionally, Chen et al recently demonstrated that ARTICLE various cationic polymer nanoparticles (∼5À8 nm diameter) gradually increase the conductance of cell membranes, with occasional discrete current steps of up to 0.9 ( 1.2 nA, as measured by patch-clamp electrophysiology of living cells. 28 A key difference with these polymeric nanoparticles and quantum dots is the larger diameter and the larger variation in diameter of the silica nanospheres investigated here.…”

Section: Resultsmentioning

confidence: 99%

Electrophysiological Characterization of Membrane Disruption by Nanoparticles

et al. 2011

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Direct contact of nanoparticles with the plasma membrane is essential for biomedical applications such as intracellular drug delivery and imaging, but the effect of nanoparticle association on membrane structure and function is largely unknown. Here we employ a sensitive electrophysiological method to assess the stability of protein-free membranes in the presence of silica nanospheres of different size and surface chemistry. It is shown that all the silica nanospheres permeabilize the lipid bilayers already at femtomolar concentrations, below reported cytotoxic values. Surprisingly, it is observed that a proportion of the nanospheres is able to translocate over the pure-lipid bilayer. Confocal fluorescence imaging of fluorescent nanosphere analogues also enables estimation of the particle density at the membrane surface; a significant increase in bilayer permeability is already apparent when less than 1% of the bilayer area is occupied by silica nanospheres. It can be envisaged that higher concentrations of nanoparticles lead to an increased surface coverage and a concomitant decrease in bilayer stability, which may contribute to the plasma membrane damage, inferred from lactate dehydrogenase release, that is regularly observed in nanotoxicity studies with cell cultures. This biophysical approach gives quantitative insight into nanosphere–bilayer interactions and suggests that nanoparticle–lipid interactions alone can compromise the barrier function of the plasma membrane.

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Section: Resultsmentioning

confidence: 99%

Electrophysiological Characterization of Membrane Disruption by Nanoparticles

et al. 2011

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“…1(a). The streptavidin-linked magnetite (Fe 3 O 4 ) nanoparticles (fluidMAG-Streptavidin, purchased from Chemicell GmbH), with an average diameter of ß100 nm [full width at half Earlier experiments have shown that an oligomeric aggregation of quantum dots on the surface of suspended bilayers forms ion-conducting nanopores [10,11]. In the present case, while undergoing Brownian motion in the buffer solution, due to thermomechanical diffusion, a number of aligned MNPs would hit the impermeable bilayer under a static magnetic field (SMF).…”

Section: Experiment: Materials and Methodsmentioning

confidence: 99%

Creation and regulation of ion channels across reconstituted phospholipid bilayers generated by streptavidin-linked magnetite nanoparticles

Mohanta

Stava

et al. 2014

Phys. Rev. E

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In this work, we explore the nature of ion-channel-like conductance fluctuations across a reconstituted phospholipid bilayer due to insertion of ∼100 nm sized, streptavidin-linked magnetite nanoparticles under static magnetic fields (SMFs). For a fixed bias voltage, the frequency of current bursts increases with the application of SMFs. Apart from a closed conductance state G(0) (≤14 pS), we identify four major conductance states, with the lowest conductance level (G(1)) being ∼126 pS. The number of channel events at G(1) is found to be nearly doubled (as compared to G(0)) at a magnetic field of 70 G. The higher-order open states (e.g., 3G(1), 5G(1)) are generally observable at larger values of biasing voltage and magnetic field. When the SMF of 145 G is applied, the multiconductance states are resolved distinctly and are assigned to the simultaneous opening and closing of several independent states. The origin of the current bursts is due to the instantaneous mechanical actuation of streptavidin-linked MNP chains across the phospholipid bilayer. The voltage-controlled, magnetogated ion channels are promising for diagnoses and therapeutic applications of excitable membranes and other biological systems.

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“…29,30 For example, electrical measurements of ENM-exposed suspended bilayers have shown that quantum dots, carbon nanotubes and polystyrene or silica nanospheres render bilayers permeable to ions, indicating a nanoparticle-induced perturbation of the bilayer structure. [31][32][33][34][35] It has also been visualized with atomic force microscopy that cationic dendrimers and silica nanospheres can create holes in mica-supported bilayers, 36 and fluorimetry measurements have demonstrated that titanium dioxide and silica nanospheres, cationic and anionic gold nanoparticles and protein-coated carbon nanotubes are all able to induce the release of fluorescent dyes from lipid vesicles. [37][38][39][40] But because most studies only concern a small number of ENM species, structure-function relationships remain elusive.…”

Section: Introductionmentioning

confidence: 99%

Native silica nanoparticles are powerful membrane disruptors

Alkhammash

Berthier

et al. 2015

Phys. Chem. Chem. Phys.

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a Silica nanoparticles are under development for intracellular drug delivery applications but can also have cytotoxic effects including cell membrane damage. In this study, we investigated the interactions of silica nanospheres of different size, surface chemistry and biocoating with membranes of phosphatidylcholine lipids. In liposome leakage assays many, but not all, of these nanoparticles induced dose-dependent dye leakage, indicative of membrane perturbation. It was found that 200 and 500 nm native-silica, aminated and carboxylated nanospheres induce near-total dye release from zwitterionic phosphatidylcholine liposomes at a particle/liposome ratio of B1, regardless of their surface chemistry, which we interpret as particlesupported bilayer formation following a global rearrangement of the vesicular membrane. In contrast, 50 nm diameter native-silica nanospheres did not induce total dye leakage below a particle/liposome ratio of B8, whereas amination or carboxylation, respectively, strongly reduced or prevented dye release. We postulate that for the smaller nanospheres, strong silica-bilayer interactions are manifested as bilayer engulfment of membrane-adsorbed particles, with localized lipid depletion eventually leading to collapse of the vesicular membrane. Protein coating of the particles considerably reduced dye leakage and lipid bilayer coating prevented dye release all together, while the inclusion of 33% anionic lipids in the liposomes reduced dye leakage for both native-silica and aminated surfaces. These results, which are compared with the effect of polystyrene nanoparticles and other engineered nanomaterials on lipid bilayers, and which are discussed in relation to nanosilica-induced cell membrane damage and cytotoxicity, indicate that a native-silica nanoparticle surface chemistry is a particularly strong membrane interaction motif.

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Current bursts in lipid bilayers initiated by colloidal quantum dots

Cited by 16 publications

References 11 publications

Electrophysiological Characterization of Membrane Disruption by Nanoparticles

Electrophysiological Characterization of Membrane Disruption by Nanoparticles

Creation and regulation of ion channels across reconstituted phospholipid bilayers generated by streptavidin-linked magnetite nanoparticles

Native silica nanoparticles are powerful membrane disruptors

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