Laurdan as a Molecular Rotor in Biological Environments

Osella, Silvio; Knippenberg, Stefan

doi:10.1021/acsabm.9b00789

Cited by 15 publications

(18 citation statements)

References 60 publications

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“…Fluorescence spectroscopies are nowadays one of the techniques of choice for the analysis of the behavior of probes in different membrane phases, due to the different responses related to the anisotropy decay [ 51 , 52 , 53 , 54 , 55 , 56 , 57 ]. We focus on the decay time and the fluorescence anisotropy decay as model analyses which can be obtained by computations [ 29 , 30 , 31 , 33 , 34 ]. The decay time analysis, which can be closely related to the fluorescence lifetime imaging (FLIM) technique, allows screening between the membrane phase and gives indication on the phase itself.…”

Section: Resultsmentioning

confidence: 99%

“…Afterwards, the focus can be put on a smaller part of the system to study optical properties by means of hybrid quantum mechanics/molecular mechanics (QM/MM) methods. In this way, many different properties such as linear and non-linear optical properties, fluorescence and photoselection of an optical probe immersed into the membrane can be assessed [ 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. The ability of the probe to give different optical responses depending on the environment it is embedded in allows to determine the phase of the membrane itself, which, in turn, is strongly related to its fluidity.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we study the optical properties of a well-known probe, diphenylhexatriene (DPH), embedded in different membrane phases, by means of a well-established QM/MM approach [ 29 , 30 , 31 , 32 , 33 ]. Model membranes have been considered, consisting of dioleoylphosphatidylcholine (DOPC), dipalmitoylphosphatidylcholine (DPPC) and a 2:1 mixture of stearoyl sphingomyelin (SM) and cholesterol (Chol) for the liquid-disordered (Ld), solid-ordered (So) and liquid-ordered (Lo) phases, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Membrane Phase on the Optical Properties of DPH

et al. 2020

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The fluorescent molecule diphenylhexatriene (DPH) has been often used in combination with fluorescence anisotropy measurements, yet little is known regarding the non-linear optical properties. In the current work, we focus on them and extend the application to fluorescence, while paying attention to the conformational versatility of DPH when it is embedded in different membrane phases. Extensive hybrid quantum mechanics/molecular mechanics calculations were performed to investigate the influence of the phase- and temperature-dependent lipid environment on the probe. Already, the transition dipole moments and one-photon absorption spectra obtained in the liquid ordered mixture of sphingomyelin (SM)-cholesterol (Chol) (2:1) differ largely from the ones calculated in the liquid disordered DOPC and solid gel DPPC membranes. Throughout the work, the molecular conformation in SM:Chol is found to differ from the other environments. The two-photon absorption spectra and the ones obtained by hyper-Rayleigh scattering depend strongly on the environment. Finally, a stringent comparison of the fluorescence anisotropy decay and the fluorescence lifetime confirm the use of DPH to gain information upon the surrounding lipids and lipid phases. DPH might thus open the possibility to detect and analyze different biological environments based on its absorption and emission properties.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Membrane Phase on the Optical Properties of DPH

et al. 2020

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“…The one-photon absorption spectra (OPA) of all the systems were analyzed and attention was paid to the nonlinear optical properties, such as two-photon absorption (TPA), and second harmonic generation phenomena. As reported in our previous studies, 25,55,64,76 the two-photon absorption cross section (in GM units) is computed as 77…”

Section: ■ Methodsmentioning

confidence: 99%

Push/Pull Effect as Driving Force for Different Optical Responses of Azobenzene in a Biological Environment

Knippenberg

Osella

2020

J. Phys. Chem. C

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The specific relationship between the alkyl tail lengths of four azobenzene probes embedded in DOPC liquid disorder membrane and their (non) linear optical (NLO) properties have been considered in the current study. Using extensive molecular dynamics calculations, the push/pull effect of the alkyl tails on the position and orientation of the probes in the model membrane are discussed. The simulations indicate that with increasing tail lengths the cis isomers are pushed closer to the membrane surface, while the trans ones are rather pulled toward the membrane center. Throughout hybrid quantum mechanics/molecular mechanics calculations, the linear and nonlinear optical properties of these compounds have been investigated. The pushing effect of the tails for cis azobenzene is translated in strong responses in the (non) linear optical spectroscopies, while the opposite is seen for the trans isomers. The cis isomer can be seen as the active state of the azobenzene compound for membrane recognition. The current work highlights the correlation between the tails of photosensitive membrane probes and their NLO properties, and focuses on unexpected behaviors of azobenzene derivatives in biological environments which can be exploited in distinguishing between soft and stiff cellular compartments that are of utmost importance for ion carrier transport.

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“…No intermixing between the two conformations is possible, at variance with the behavior previously observed in fluid DOPC [ 75 ]. This study was continued in a more recent report, focused on optical properties calculated using QM/MM [ 78 ]. The solvatochromic nature of laurdan is apparent on the calculated optical properties, which can be affected by the presence of two different conformers.…”

Section: Charge-transfer-based and Other Solvatochromic Probesmentioning

confidence: 99%

The Secret Lives of Fluorescent Membrane Probes as Revealed by Molecular Dynamics Simulations

2020

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Fluorescent probes have been employed for more than half a century to study the structure and dynamics of model and biological membranes, using spectroscopic and/or microscopic experimental approaches. While their utilization has led to tremendous progress in our knowledge of membrane biophysics and physiology, in some respects the behavior of bilayer-inserted membrane probes has long remained inscrutable. The location, orientation and interaction of fluorophores with lipid and/or water molecules are often not well known, and they are crucial for understanding what the probe is actually reporting. Moreover, because the probe is an extraneous inclusion, it may perturb the properties of the host membrane system, altering the very properties it is supposed to measure. For these reasons, the need for independent methodologies to assess the behavior of bilayer-inserted fluorescence probes has been recognized for a long time. Because of recent improvements in computational tools, molecular dynamics (MD) simulations have become a popular means of obtaining this important information. The present review addresses MD studies of all major classes of fluorescent membrane probes, focusing in the period between 2011 and 2020, during which such work has undergone a dramatic surge in both the number of studies and the variety of probes and properties accessed.

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Laurdan as a Molecular Rotor in Biological Environments

Cited by 15 publications

References 60 publications

Influence of Membrane Phase on the Optical Properties of DPH

Influence of Membrane Phase on the Optical Properties of DPH

Push/Pull Effect as Driving Force for Different Optical Responses of Azobenzene in a Biological Environment

The Secret Lives of Fluorescent Membrane Probes as Revealed by Molecular Dynamics Simulations

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