Imaging intracellular viscosity of a single cell during photoinduced cell death

Kuimova, Marina K.; Botchway, Stanley W.; Parker, Anthony W.; Baláž, Milan; Collins, Hugh; Anderson, Harry L.; Suhling, Klaus; Ogilby, Peter R.

doi:10.1038/nchem.120

Cited by 578 publications

(553 citation statements)

References 33 publications

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“…Moreover, we have previously demonstrated, using a ratiometric method and a dimer 2 that the viscosity in a single cell increased dramatically during irradiation of the dimer leading to cell death. 17 The results of an irradiation of a DOPC monolayer containing 1 are shown in Figure 5a on the left, and the average viscosity values obtained from these images in Figure 5b. A large viscosity increase of 6 fold is observed, from 4 to 24 cP (ratiometric), which was almost completely supressed in the presence of 0.11M NaN 3 , an efficient singlet oxygen quencher (Figure 5a middle).…”

Section: Resultsmentioning

confidence: 99%

“…It is now well established that quantitative imaging of viscosity requires either ratiometric detection or fluorescence lifetime measurements, in order to rule out the effect of the concentration of the probe on the observed signal. [16][17][18][19] Consequently, both types of molecular rotors, using either ratiometric or lifetime detection, have been reported and used for imaging in a variety of systems, from live cells to lipid membranes to atmospheric aerosols. 2,[16][17][18]20 Here we report a red emitting molecular rotor 1, Figure 1a, previously synthesized by Balaz et.…”

Section: Introductionmentioning

confidence: 99%

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Dual mode quantitative imaging of microscopic viscosity using a conjugated porphyrin dimer

Vyšniauskas

Baláž

Anderson

et al. 2015

Phys. Chem. Chem. Phys.

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Microviscosity is of paramount importance in materials and bio-sciences. Fluorescence imaging using molecular rotors has emerged as a versatile tool to measure microviscosity, either using a fluorescence lifetime or a ratiometric signal of the rotor; however, only a limited number of blue -to-green-emitting fluorophores with both the lifetime and the ratiometric signal sensitivity to viscosity have been reported to date. Here we report a deep red emitting dual viscosity sensor, which allows both the ratiometric and the lifetime imaging of viscosity. We study viscosity in a range of lipid-based systems and conclude that in complex dynamic systems dual detection is preferable in order to independently verify the results of the measurements as well as perform rapid detection of changing viscosity .

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dual mode quantitative imaging of microscopic viscosity using a conjugated porphyrin dimer

Vyšniauskas

Baláž

Anderson

et al. 2015

Phys. Chem. Chem. Phys.

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“…Consequently, both emission wavelength and quantum yield are influenced by multiple concomitant solvent properties that need to be taken into account when the fluorescence signal is interpreted. None the less, several studies demonstrate that the information provided by the fluorescence of molecular rotors is useful, and molecular rotors have been used, for example, to investigate protein conformal changes [16,17], phopsholipid bilayer microviscosity [7], and the microviscosity of the interior of cells [18]. We reported an intriguing new phenomenon, whereby the fluorescence emission intensity increases in moving fluids [19].…”

Section: Introductionmentioning

confidence: 82%

Apparent Shear Sensitivity of Molecular Rotors in Various Solvents

et al. 2015

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Fluorescent environment-sensitive dyes often change their spectral properties concomitantly with multiple solvent properties, such as polarity, protonation, hydrogen bond formation, or viscosity. Careful consideration of the response is needed when a fluorescent dye is used to report a single property. Recently, we observed an increase of emission intensity of viscosity-sensitive molecular rotors in fluids subject to flow and speculated that either polar-polar interaction or hydrogen bond formation play a role in the apparent flow sensitivity. In this study, we show experimental evidence that photoisomerization to an isomer with a lower quantum yield, first proposed by Rumble et al. (J Phys Chem A 116(44):10786-10792, 2012), plays a key role in the observed phenomenon. We subjected four molecular rotors with different electron acceptor motifs to fluid flow in solvents of different polarity and ability to form hydrogen bonds. We also measured the isomerization dynamics in a custom fluorophotometer with extremely low light exposure. Our results indicate that the photoisomerization rate depends both on the solvent and on the electron acceptor group, as does the recovery of the original isomer in the dark. In most solvents, recovery of the dark isomer is much more rapid than originally reported, and a state of quasiequilibrium between both isomers is possible. Moreover, the sensitivity (i.e., relative intensity increase at the same flow rate) is also solvent-dependent. The intensity increase can be detected at very low velocities (as low as 0.06 mm/s). Characteristic for fluorescent dyes is the high spatial resolution, and no flow measurement device with comparable sensitivity and spatial resolution exists, although the nature of the solvent needs to be taken into account for quantitative flow measurement.

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“…In this work, we utilized BODIPY‐C 10 17, 18 (Figure 1), a fluorophore that belongs to a group of dyes termed ‘molecular rotors’ that have viscosity‐dependent fluorescence quantum yields, lifetimes,19, 20 and depolarization 21, 22. When combined with fluorescence lifetime imaging microscopy (FLIM), molecular rotors can be used to obtain spatially resolved viscosity maps of microscopic objects,17, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 as well as to observe dynamic change in viscosity during relevant processes of interest 37, 39, 41, 42. Thus, we aimed to use BODIPY‐C 10 , which is known to completely embed into the fluid‐phase lipid bilayers40 to directly examine how photooxidation during PDT affects viscoelastic properties of model lipid membranes, with spatial‐ and time‐resolution.…”

Section: Introductionmentioning

confidence: 99%

A Molecular Rotor that Measures Dynamic Changes of Lipid Bilayer Viscosity Caused by Oxidative Stress

Vyšniauskas

Qurashi

Kuimova

2016

Chemistry A European J

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Oxidation of cellular structures is typically an undesirable process that can be a hallmark of certain diseases. On the other hand, photooxidation is a necessary step of photodynamic therapy (PDT), a cancer treatment causing cell death upon light irradiation. Here, the effect of photooxidation on the microscopic viscosity of model lipid bilayers constructed of 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine has been studied. A molecular rotor has been employed that displays a viscosity‐dependent fluorescence lifetime as a quantitative probe of the bilayer's viscosity. Thus, spatially‐resolved viscosity maps of lipid photooxidation in giant unilamellar vesicles (GUVs) were obtained, testing the effect of the positioning of the oxidant relative to the rotor in the bilayer. It was found that PDT has a strong impact on viscoelastic properties of lipid bilayers, which ‘travels’ through the bilayer to areas that have not been irradiated directly. A dramatic difference in viscoelastic properties of oxidized GUVs by Type I (electron transfer) and Type II (singlet oxygen‐based) photosensitisers was also detected.

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Imaging intracellular viscosity of a single cell during photoinduced cell death

Cited by 578 publications

References 33 publications

Dual mode quantitative imaging of microscopic viscosity using a conjugated porphyrin dimer

Dual mode quantitative imaging of microscopic viscosity using a conjugated porphyrin dimer

Apparent Shear Sensitivity of Molecular Rotors in Various Solvents

A Molecular Rotor that Measures Dynamic Changes of Lipid Bilayer Viscosity Caused by Oxidative Stress

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