Total internal reflection fluorescence microscopy for determination of size of individual immobilized vesicles: Theory and experiment

Olsson, Thomas; Zhdanov, Vladimir P.; Höök, Fredrik

doi:10.1063/1.4928083

Cited by 22 publications

(29 citation statements)

References 107 publications

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“…In TIRFM or SPR experiments with vesicles immobilized at the interface, the signal measured is induced by the evanescent field. In particular, the signal can in general be described as [see, e.g., the articles by Boukobza et al (2001) and Olsson et al (2015) for TIRFM and by Jung et al (1998) and Rupert et al (2016)…”

Section: Tirfm Spr and Vesicle Deformationmentioning

confidence: 99%

“…For spherically-shaped vesicles ( Fig. 1b; Eq. 3), expression (21) yields (Olsson et al 2015;Rupert et al 2016) If vesicles are represented as an elongated pellet ( Fig. 1b; Eqs.…”

Section: For Spr Respectively]mentioning

confidence: 99%

“…(2001) and Olsson et al (2015)], surface plasmon resonance [SPR; reviewed by Jung et al (1998) and Rupert et al (2016)], or localized surface plasmon resonance [LSPR; reviewed by Jackman et al (2017)]. Vice versa, one can say that the vesicle deformation influences the TIRFM, SPR, and LSPR signals, and this effect can be important from the perspective of related applications of these techniques.…”

Section: Introductionmentioning

confidence: 99%

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Ligand-receptor-mediated attachment of lipid vesicles to a supported lipid bilayer

Zhdanov

2020

Eur Biophys J

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The interaction of exosomes (cell-secreted ∼100 nm-sized extracellular vesicles) or membrane-enveloped virions with cellular lipid membranes is often mediated by relatively weak ligand-receptor bonds. Interactions of this type can be studied using vesicles and observing their attachment to receptors located in a lipid bilayer formed at a solid surface. The contact region between a vesicle and the supported lipid bilayer and accordingly the number of ligand-receptor pairs there can be increased by deforming a vesicle. Herein, I (i) estimate theoretically the corresponding deformation energy assuming a disk-like or elongated shape of vesicles, (ii) present the equations allowing one to track such deformations by employing total internal reflection fluorescence microscopy and surface plasmon resonance, and (iii) briefly discuss some related experimental studies.

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Section: Tirfm Spr and Vesicle Deformationmentioning

confidence: 99%

“…For spherically-shaped vesicles ( Fig. 1b; Eq. 3), expression (21) yields (Olsson et al 2015;Rupert et al 2016) If vesicles are represented as an elongated pellet ( Fig. 1b; Eqs.…”

Section: For Spr Respectively]mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ligand-receptor-mediated attachment of lipid vesicles to a supported lipid bilayer

Zhdanov

2020

Eur Biophys J

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“…In particular, the NTA data points (grey dots) showed strong fluctuations, making it impossible to resolve the expected scaling ( I ∝ R 2 , solid line) in this parameter plot. For 2D flow nanometry (black dots), much lower fluctuations were observed and the expected scaling ( I ∝ R 2 , solid line) 36 is clearly resolved in the range down to 15 nm, illustrating that maintaining vesicles in the focal plane during the whole measurement enables accurate determination of I .…”

Section: Resultsmentioning

confidence: 92%

Two-dimensional flow nanometry of biological nanoparticles for accurate determination of their size and emission intensity

Block¹,

Fast²,

Lundgren³

et al. 2016

Nat Commun

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Biological nanoparticles (BNPs) are of high interest due to their key role in various biological processes and use as biomarkers. BNP size and composition are decisive for their functions, but simultaneous determination of both properties with high accuracy remains challenging. Optical microscopy allows precise determination of fluorescence/scattering intensity, but not the size of individual BNPs. The latter is better determined by tracking their random motion in bulk, but the limited illumination volume for tracking this motion impedes reliable intensity determination. Here, we show that by attaching BNPs to a supported lipid bilayer, subjecting them to hydrodynamic flows and tracking their motion via surface-sensitive optical imaging enable determination of their diffusion coefficients and flow-induced drifts, from which accurate quantification of both BNP size and emission intensity can be made. For vesicles, the accuracy of this approach is demonstrated by resolving the expected radius-squared dependence of their fluorescence intensity for radii down to 15 nm.

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“…Several microscopy modalities are available, such as laser-scanning confocal microscopy, 15 epi-fluorescence microscopy, 16 and total internal reflection fluorescence (TIRF) microscopy. 21 Indeed, singleparticle fluorescence-based methods have reported on size distributions of populations of vesicles, 15,16,22 lamellarity, 14,17 and encapsulation efficiency. 19,23 Typically, the size of an individual vesicle is quantified using the total intensity measured from fluorophores in its bilayers: If a vesicle is spherical and unilamellar, that intensity is proportional to the square of the radius of the vesicle, which allows calculation of the latter, in principle.…”

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confidence: 99%

How To Characterize Individual Nanosize Liposomes with Simple Self-Calibrating Fluorescence Microscopy

et al. 2018

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Nanosize lipid vesicles are used extensively at the interface between nanotechnology and biology, e.g., as containers for chemical reactions at minute concentrations and vehicles for targeted delivery of pharmaceuticals. Typically, vesicle samples are heterogeneous as regards vesicle size and structural properties. Consequently, vesicles must be characterized individually to ensure correct interpretation of experimental results. Here we do that using dual-color fluorescence labeling of vesicles-of their lipid bilayers and lumens, separately. A vesicle then images as two spots, one in each color channel. A simple image analysis determines the total intensity and width of each spot. These four data all depend on the vesicle radius in a simple manner for vesicles that are spherical, unilamellar, and optimal encapsulators of molecular cargo. This permits identification of such ideal vesicles. They in turn enable calibration of the dual-color fluorescence microscopy images they appear in. Since this calibration is not a separate experiment but an analysis of images of vesicles to be characterized, it eliminates the potential source of error that a separate calibration experiment would have been. Nonideal vesicles in the same images were characterized by how their four data violate the calibrated relationship established for ideal vesicles. In this way, our method yields size, shape, lamellarity, and encapsulation efficiency of each imaged vesicle. Applying this procedure to extruded samples of vesicles, we found that, contrary to common assumptions, only a fraction of vesicles are ideal.

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Total internal reflection fluorescence microscopy for determination of size of individual immobilized vesicles: Theory and experiment

Cited by 22 publications

References 107 publications

Ligand-receptor-mediated attachment of lipid vesicles to a supported lipid bilayer

Ligand-receptor-mediated attachment of lipid vesicles to a supported lipid bilayer

Two-dimensional flow nanometry of biological nanoparticles for accurate determination of their size and emission intensity

How To Characterize Individual Nanosize Liposomes with Simple Self-Calibrating Fluorescence Microscopy

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