In Situ Amperometric Characterization of Liposome Suspensions with Concomitant Oxygen Reduction

DeNardis, Nadica Ivošević; Žutić, Vera; Svetličić, Vesna; Frkanec, Ruža; Tomašić, Jelka

doi:10.1002/elan.200703999

Cited by 17 publications

(17 citation statements)

References 32 publications

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“…However, adhesion-spreading events have been recorded also close to the point of zero charge on a mercury electrode 46 , suggesting either a spontaneous activation-deactivation process inherent to the liposomes or a different mechanism by which the surface may induce the activation.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic Heterogeneity in Liposome Suspensions Caused by the Dynamic Spontaneous Formation of Hydrophobic Active Sites in Lipid Membranes

Hernández

Edwards

2011

Langmuir

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The spontaneous, dynamic formation of hydrophobic active sites in lipid bilayer membranes is studied and characterized. It is shown that the rates of formation and consumption of these active sites control at least two important properties of liposomes: their affinity for hydrophobic surfaces and the rate by which they spontaneously release encapsulated molecules. The adhesion and spreading of liposomes onto hydrophobic polystyrene nanoparticles and the spontaneous leakage of an encapsulated fluorescent dye were monitored for different liposome compositions employing Cryo-TEM, DLS and fluorescence measurements. It was observed that an apparently homogeneous, monodisperse liposome suspension behaves as if composed by two different populations: a fast leaking population that presents affinity for the hydrophobic substrate employed, and a slow leaking population that does not attach immediately to it. The results reported here suggest that the proportion of liposomes in each population changes over time until a dynamic equilibrium is reached. It is shown that this phenomenom can lead to irreproducibility in, e.g., spontaneous leakage experiments, as extruded liposomes leak much faster just after preparation than 24 hours afterwards. Our findings account for discrepancies in several experimental results reported in the literature. To our knowledge, this is the first systematic study addressing the issue of an existing intrinsic heterogeneity of liposome suspensions.

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Section: Introductionmentioning

confidence: 99%

Intrinsic Heterogeneity in Liposome Suspensions Caused by the Dynamic Spontaneous Formation of Hydrophobic Active Sites in Lipid Membranes

Hernández

Edwards

2011

Langmuir

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“…where 12  , 13  and 23  are the interfacial energies at mercury/water, mercury/organic liquid and water/organic liquid interfaces, respectively.…”

Section: Electrochemical Methodsmentioning

confidence: 99%

“…Each amperometric signal corresponds to the adhesion of a single particle from suspension [9,12]. Random occurrence of the adhesion events is due to the spatial heterogeneity inherent to a dispersed system and to the stochastic nature of the particles' encounter with the electrode.…”

Section: Electrochemical Methodsmentioning

confidence: 99%

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Cell adhesion and spreading at a charged interface: Insight into the mechanism using surface techniques and mathematical modelling

DeNardis

Pečar-Ilić

Ružić

et al. 2015

Electrochimica Acta

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Please cite this article as: Nadica Ivošević DeNardis, Jadranka Pečar Ilić, Ivica Ružić, Galja Pletikapić, Cell adhesion and spreading at a charged interface: Insight into the mechanism using surface techniques and mathematical modelling, Electrochimica Acta http://dx.(N. Ivošević DeNardis) 1 ISE member Highlights  Kinetics of adhesion and spreading of the algal cell at a charged interface is explored. Amperometric signals are analyzed using extended methodology and the reaction kinetics model.  The model reconstructs and quantifies individual states of the three-step adhesion process. Adhesion kinetics of the algal cell is slower than that of its plasma membrane vesicle. Slow spreading of organic film at the interface could be due to the attenuated effect of the potential. AbstractWe study the kinetics of adhesion and spreading of an algal cell and its plasma membrane vesicle at the charged interface. A simple system of an isolated plasma membrane vesicle without internal content has been developed and characterized by atomic force microscopy (AFM). We extend the methodology based on the reaction kinetics model and empirical fitting for the analysis of amperometric signals, and demonstrate its validity and pertinence in a wide range of surface charge densities. Adhesion kinetics of the algal cell is slower than that of its plasma membrane vesicle. Isolated plasma membrane contributes about one quarter to the cell contact area. The model reconstructs and quantifies individual states of the three-step adhesion process of the algal cell and makes it possible to associate them with various features of amperometric signal. At the time of current amplitude, the ruptured state predominates and the cell contact area is larger than its initial area as well as the contact area of the plasma membrane vesicle. These results suggest that a major structural disruption of the cell membrane, collapse of cytoskeleton and leakage of intracellular material could appear close to the time of current amplitude. Further, kinetics of the organic film spreading at the interface to its maximal extent is considered as the rate determining step, which could be a consequence of the attenuated effect of potential at the modified interface, stronger intermolecular interactions and reorganization of molecules in the film. Our findings offer an insight into the mechanism of algal cell adhesion and spreading at charged interfaces, relevant for electroporation based studies.

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“…However, adhesion-spreading of liposomes on mercury surfaces has been recorded also at the point of zero charge [33].…”

Section: Adhesion and Spreading Of Liposomes On Hydrophobic Nanopartimentioning

confidence: 99%

The theory of metal electronucleation applied to the study of fundamental properties of liposomes

Hernández

2012

J Solid State Electrochem

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In Situ Amperometric Characterization of Liposome Suspensions with Concomitant Oxygen Reduction

Cited by 17 publications

References 32 publications

Intrinsic Heterogeneity in Liposome Suspensions Caused by the Dynamic Spontaneous Formation of Hydrophobic Active Sites in Lipid Membranes

Intrinsic Heterogeneity in Liposome Suspensions Caused by the Dynamic Spontaneous Formation of Hydrophobic Active Sites in Lipid Membranes

Cell adhesion and spreading at a charged interface: Insight into the mechanism using surface techniques and mathematical modelling

The theory of metal electronucleation applied to the study of fundamental properties of liposomes

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