Electrochemistry and in situ fluorescence microscopy of octadecanol layers doped with a BODIPY-labeled phospholipid: Investigating an adsorbed heterogeneous layer

Casanova-Moreno, Jannu; Bizzotto, Dan

doi:10.1016/j.jelechem.2010.02.015

Cited by 4 publications

(9 citation statements)

References 51 publications

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“…The apparent insensitivity of capacitance to the changes in the adsorbed layer as seen by fluorescence deserves comment, as does the range of initial fluorescence intensities. Previous fluorescence imaging studies 36 have shown that floating octadecanol monolayers with 3 mol % of a lipophillic fluorophore, as used in this experiment, have a variety of structures and intensities that are retained when the layer is transferred to the electrode surface. Fluorescent images of an octadecanol-modified electrode showed a variety of intensities and structures.…”

Section: Top)mentioning

confidence: 99%

“…The Au(111) surface was further characterized using in situ fluorescence measurements performed using a spectroelectrochemical cell (built in-house with a 250 μm optical window as the base of the cell 36 ) and an inverted/ epifluorescence microscope (Olympus IX70) fitted with an EM-CCD (Evolve-512 by Photometrics) and a light source (EXFO Exacte) using a 50× objective (Olympus LMPlan-FL) and a customassembled fluorescence filter cube tailored for BODIPY monomer fluorescence. 36 The microscope setup was housed in a light-tight box. Changes in potential, electrochemical measurements, and fluorescence images were triggered and recorded simultaneously, as controlled by a custom LabView program.…”

Section: ■ Introductionmentioning

confidence: 99%

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Potential-Dependent Interaction of DOPC Liposomes with an Octadecanol-Covered Au(111) Surface Investigated Using Electrochemical Methods Coupled with in Situ Fluorescence Microscopy

et al. 2013

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The potential-controlled incorporation of DOPC liposomes (100 nm diameter) into an adsorbed octadecanol layer on Au(111) was studied using electrochemical and in situ fluorescence microscopy. The adsorbed layer of octadecanol included a small amount of a lipophilic fluorophore-octadecanol modified with BODIPY-to enable fluorescence imaging. The deposited octadecanol layer was found not to allow liposomes to interact unless the potential was less than -0.4 V/SCE, which introduces defects into the adsorbed layer. Small increases in the capacitance of the adsorbed layer were measured after introducing the defects, allowing the liposomes to interact with the defects and then annealing the defects at 0 V/SCE. A change in the adsorbed layer was also signified by a more positive desorption potential for the liposome-modified adsorbed layer as compared to that for an adsorbed layer that was porated in a similar fashion but without liposomes present in the electrolyte. These subtle changes in capacitance are difficult to interpret, so an in situ spectroscopic study was performed to provide a more direct measure of the interaction. The incorporation of liposomes should result in an increase in the fluorescence measured because the fluorophore should become further separated from the gold surface, reducing the efficiency of fluorescence quenching. No significant increase in the fluorescence of the adsorbed layer was observed during the potential pulses used in the poration procedure in the absence of liposomes. In the presence of liposomes, the fluorescence intensity was found to depend on the potential and time used for poration. At 0 V/SCE, no significant change in the fluorescence was observed for defect-free adsorbed layers. Changing the poration potential to -0.4 V/SCE caused significant increases in the fluorescence and the appearance of new structural features in the adsorbed layers that were more easily observed during the desorption procedure. The extent of fluorescence changes was found to be strongly dependent on the nature of the adsorbed layer under investigation, which suggests that the poration and liposome interaction are dependent on the quality of the adsorbed layer and its ease of poration through changes in the electrode potential.

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Section: Top)mentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Potential-Dependent Interaction of DOPC Liposomes with an Octadecanol-Covered Au(111) Surface Investigated Using Electrochemical Methods Coupled with in Situ Fluorescence Microscopy

et al. 2013

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“…A monolayer of adsorbed octadecanol is 2.2 nm thick as measured by neutron reflectometry in an electrochemical environment, 25,49 which suggests that these crystals are two or three monolayers above an already-adsorbed layer. These small features are very likely due to the deposition procedure where small crystallites present in the floating layer become deposited onto the Au surface, as also observed in previous fluorescence imaging data 50 though at lower resolution. These small features do not change over the multiple imaging scans when the potential is held at 0 V/RE.…”

Section: ■ Methods and Materialsmentioning

confidence: 99%

Potential Controls the Interaction of Liposomes with Octadecanol-Modified Au Electrodes: An in Situ AFM Study

Musgrove

Bizzotto

2015

Langmuir

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The formation of supported lipid bilayers using liposomes requires interaction with the solid surface, rupture of the liposome, and spreading to cover the surface with a lipid bilayer. This can result in a less-than-uniform coating of the solid surface. Presented is a method that uses the electrochemical poration of an adsorbed lipid-like layer on a Au electrode to control the interaction of 100 nm DOPC liposomes. An octadecanol-coated Au-on-mica surface was imaged using tapping-mode AFM during the application of potential in the presence or absence of liposomes. When the substrate potential was made negative enough, defects formed in the adsorbed layer and new taller features were observed. More features were observed and existing features increased in size with time spent at this negative poration potential. The new features were 1.8-2.0 nm higher than the octadecanol-coated gold surface, half the thickness of a DOPC bilayer. These features were not observed in the absence of liposomes when undergoing the same potential perturbation. In the presence of liposomes, the application of a poration potential was needed to initiate the formation of these taller features. Once the applied potential was removed, the features stopped growing and no new regions were observed. The size of these new regions was consistent with the footprint of a flattened 100 nm liposome. It is speculated that the DOPC liposomes were able to interact with the defects and became soluble in the octadecanol, creating a taller region that was limited in size to the liposome that adsorbed and became incorporated. This AFM study confirms previous in situ fluorescence measurements of the same system and illustrates the use of a potential perturbation to control the formation of these regions of increased DOPC content.

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“…The modified surface was characterized using in-situ fluorescence microscopy as described previously [44,36,35,34,57]. Briefly, a custom spectroelectrochemical cell with a 250 m glass optical window as the bottom is used with an inverted microscope (Olympus IX-70) configured as shown in Figure 1.…”

Section: In-situ Fluorescence Imaging Spectroelectrochemistrymentioning

confidence: 99%

“…Their objective is to analyze the potential dependent changes in the adsorbed layer rather than measurement of a rate of change of the interfacial characteristics. We have also used this approach in the analysis of potential induced changes in an adsorbed organic layer on gold electrodes [33][34][35][36] which will be further demonstrated in this contribution.…”

Section: Introductionmentioning

confidence: 99%

Frequency response analysis of potential-modulated orientation changes of a DNA self assembled layer using spatially resolved fluorescence measurements.

Casanova-Moreno

Bizzotto

2015

Electrochimica Acta

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Electrochemistry and in situ fluorescence microscopy of octadecanol layers doped with a BODIPY-labeled phospholipid: Investigating an adsorbed heterogeneous layer

Cited by 4 publications

References 51 publications

Potential-Dependent Interaction of DOPC Liposomes with an Octadecanol-Covered Au(111) Surface Investigated Using Electrochemical Methods Coupled with in Situ Fluorescence Microscopy

Potential-Dependent Interaction of DOPC Liposomes with an Octadecanol-Covered Au(111) Surface Investigated Using Electrochemical Methods Coupled with in Situ Fluorescence Microscopy

Potential Controls the Interaction of Liposomes with Octadecanol-Modified Au Electrodes: An in Situ AFM Study

Frequency response analysis of potential-modulated orientation changes of a DNA self assembled layer using spatially resolved fluorescence measurements.

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