scholarly journals Confocal Microscopy Confirmed that in Phosphatidylcholine Giant Unilamellar Vesicles with very High Cholesterol Content Pure Cholesterol Bilayer Domains Form

2019 ◽  
Vol 77 (4) ◽  
pp. 309-317 ◽  
Author(s):  
Marija Raguz ◽  
Suresh N. Kumar ◽  
Mariusz Zareba ◽  
Nada Ilic ◽  
Laxman Mainali ◽  
...  
Membranes ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 860
Author(s):  
Zvonimir Boban ◽  
Ivan Mardešić ◽  
Witold Karol Subczynski ◽  
Marija Raguz

Since its inception more than thirty years ago, electroformation has become the most commonly used method for growing giant unilamellar vesicles (GUVs). Although the method seems quite straightforward at first, researchers must consider the interplay of a large number of parameters, different lipid compositions, and internal solutions in order to avoid artifactual results or reproducibility problems. These issues motivated us to write a short review of the most recent methodological developments and possible pitfalls. Additionally, since traditional manual analysis can lead to biased results, we have included a discussion on methods for automatic analysis of GUVs. Finally, we discuss possible improvements in the preparation of GUVs containing high cholesterol contents in order to avoid the formation of artifactual cholesterol crystals. We intend this review to be a reference for those trying to decide what parameters to use as well as an overview providing insight into problems not yet addressed or solved.


The Analyst ◽  
2020 ◽  
Vol 145 (24) ◽  
pp. 7922-7931
Author(s):  
Pauline Lefrançois ◽  
Bertrand Goudeau ◽  
Stéphane Arbault

Giant unilamellar vesicles were used as individual biomimetic micro-reactors wherein a model bi-enzymatic reaction involving a glucose oxidase (GOx) and horseradish peroxidase (HRP) was monitored by confocal microscopy.


2011 ◽  
Vol 2 (7) ◽  
pp. 713-718 ◽  
Author(s):  
Silvia Nappini ◽  
Tamer Al Kayal ◽  
Debora Berti ◽  
Bengt Nordèn ◽  
Piero Baglioni

2020 ◽  
Author(s):  
Hammad A. Faizi ◽  
Cody J. Reeves ◽  
Vasil N. Georgiev ◽  
Petia M. Vlahovska ◽  
Rumiana Dimova

A widely used method to measure the bending rigidity of bilayer membranes is fluctuation spectroscopy, which analyses the thermally-driven membrane undulations of giant unilamellar vesicles recorded with either phase-contrast or confocal microscopy. Here, we analyze the fluctuations of the same vesicle using both techniques and obtain consistent values for the bending modulus. We discuss the factors that may lead to discrepancies.


Author(s):  
David W. Piston ◽  
Brian D. Bennett ◽  
Robert G. Summers

Two-photon excitation microscopy (TPEM) provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging and photochemistry. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In practice, two-photon excitation is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10-5 maintains the average input power on the order of 10 mW, only slightly greater than the power normally used in confocal microscopy.


Author(s):  
David W. Piston

Two-photon excitation fluorescence microscopy provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In our fluorescence experiments, the final excited state is the same singlet state that is populated during a conventional fluorescence experiment. Thus, the fluorophore exhibits the same emission properties (e.g. wavelength shifts, environmental sensitivity) used in typical biological microscopy studies. In practice, two-photon excitation is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10−5 maintains the average input power on the order of 10 mW, only slightly greater than the power normally used in confocal microscopy.


Life ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 634
Author(s):  
Ylenia Miele ◽  
Gábor Holló ◽  
István Lagzi ◽  
Federico Rossi

The budding and division of artificial cells engineered from vesicles and droplets have gained much attention in the past few decades due to an increased interest in designing stimuli-responsive synthetic systems. Proper control of the division process is one of the main challenges in the field of synthetic biology and, especially in the context of the origin of life studies, it would be helpful to look for the simplest chemical and physical processes likely at play in prebiotic conditions. Here we show that pH-sensitive giant unilamellar vesicles composed of mixed phospholipid/fatty acid membranes undergo a budding process, internally fuelled by the urea–urease enzymatic reaction, only for a given range of the membrane composition. A gentle interplay between the effects of the membrane composition on the elasticity and the preferred area difference of the bilayer is responsible for the existence of a narrow range of membrane composition yielding a high probability for budding of the vesicles.


Langmuir ◽  
2021 ◽  
Vol 37 (3) ◽  
pp. 1082-1088
Author(s):  
Chiho Kataoka-Hamai ◽  
Kohsaku Kawakami

Soft Matter ◽  
2021 ◽  
Author(s):  
Peng Bao ◽  
Daniel A. Paterson ◽  
Sally A. Peyman ◽  
J. Cliff Jones ◽  
Jonathan A. T. Sandoe ◽  
...  

We describe a modified microfluidic method for making Giant Unilamellar Vesicles (GUVs) via water/octanol-lipid/water double emulsion droplets and encapsulation of nematic lyotropic liquid crystals (LNLCs).


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