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Okita K, Ito N, Morishita-Watanabe N, Umakoshi H, Kasahara K, Matubayasi N. Solvation dynamics on the diffusion timescale elucidated using energy-represented dynamics theory. Phys Chem Chem Phys 2024; 26:12852-12861. [PMID: 38623745 DOI: 10.1039/d4cp00235k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
Photoexcitation of a solute alters the solute-solvent interaction, resulting in the nonequilibrium relaxation of the solvation structure, often called a dynamic Stokes shift or solvation dynamics. Thanks to the local nature of the solute-solvent interaction, the characteristics of the local solvent environment dissolving the solute can be captured by the observation of this process. Recently, we derived the energy-represented Smoluchowski-Vlasov (ERSV) equation, a diffusion equation for molecular liquids, which can be used to analyze the solvation dynamics on the diffusion timescale. This equation expresses the time development for the solvent distribution on the solute-solvent pair interaction energy (energy coordinate). Since the energy coordinate can effectively treat the solvent flexibility in addition to the position and orientation, the ERSV equation can be utilized in various solvent systems. Here, we apply the ERSV equation to the solvation dynamics of 6-propionyl-2-dimethylamino naphthalene (Prodan) in water and different alcohol solvents (methanol, ethanol, and 1-propanol) for clarifying the differences of the relaxation processes among these solvents. Prodan is a solvent-sensitive fluorescent probe and is thus widely utilized for investigating heterogeneous environments. On the long timescale, the ERSV equation satisfactorily reproduces the relaxation time correlation functions obtained from the molecular dynamics (MD) simulations for these solvents. We reveal that the relaxation time coefficient on the diffusion timescale linearly correlates with the inverse of the translational diffusion coefficients for the alcohol solvents because of the Prodan-solvent energy distributions among the alcohols. In the case of water, the time coefficient deviates from the linear relationship for the alcohols due to the difference in the extent of importance of the collective motion between the water and alcohol solvents.
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Affiliation(s)
- Kazuya Okita
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Natsuumi Ito
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Nozomi Morishita-Watanabe
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Hiroshi Umakoshi
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Kento Kasahara
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Nobuyuki Matubayasi
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
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Huang A, Adler J, Parmryd I. Optimised generalized polarisation analysis of C-laurdan reveals clear order differences between T cell membrane compartments. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184094. [PMID: 36379264 DOI: 10.1016/j.bbamem.2022.184094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 11/09/2022] [Accepted: 11/10/2022] [Indexed: 11/15/2022]
Abstract
Heterogenous packing of plasma membrane lipids is important for cellular processes like signalling, adhesion and sorting of membrane components. Solvatochromic membrane fluorophores that respond to changes from liquid-ordered (lo) phase to liquid-disordered (ld) by red shifts in their emission spectra are often used to assess lipid packing. Their response can be quantified using generalized polarisation (GP) using fluorescence microscopy images from two emission ranges, preferably from a region of interest (ROI) limited to a specific membrane compartment. However, image quality is limited by Poisson noise and convolution by the point spread function of the imaging system. Examining GP-analysis of C-laurdan labelled T cells using the image restoration procedure deconvolution, we demonstrate that deconvolution substantially improves the image resolution by making the plasma membrane clearly discernible and facilitating plasma membrane ROI selection. We conclude that automatic ROI selection has advantages over manual ROI selection when it comes to reproducibility and speed, but reliable GP-measurements can also be obtained by manually demarcated ROIs. We find that deconvolution enhances the difference in GP-values between the plasma and intracellular membranes and demonstrate that moving an intensity defined plasma membrane ROI outwards from the cell further improves this differentiation. By systematically changing the key deconvolution regularization parameter signal to noise, we establish a protocol for deconvolution optimisation applicable to any solvatochromic dye and imaging system. The image processing and ROI selection protocol presented improves both the resolution and precision of GP-measurement and will enable detection of smaller changes in membrane order than is currently achievable.
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Affiliation(s)
- Ainsley Huang
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Jeremy Adler
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Ingela Parmryd
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
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Franchino H, Stevens E, Nelson J, Bell TA, Bell JD. Wavelength dependence of patman equilibration dynamics in phosphatidylcholine bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:877-86. [PMID: 22954647 DOI: 10.1016/j.bbamem.2012.08.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 08/22/2012] [Accepted: 08/28/2012] [Indexed: 10/27/2022]
Abstract
Assessment of the equilibration kinetics of Patman at the edges of its emission spectra provided additional insights about membrane properties beyond those obtained from end-point fluorescence measurements. Upon introduction of the probe to aqueous suspensions of liposomes, the emission intensity slowly increased about 10-fold (t(½)=~100 s). The rate of equilibration depended on emission wavelength, and was usually faster at 500 than at 435 nm. However, this trend was reversed for equilibration with lipids at their phase transition temperature. The apparent rotational motion of the dye also differed between the long and short emission wavelengths but did not display the slow equilibration time dependence observed with intensity measurements. These results suggested that slow equilibration reflects relaxation of the immediate membrane microenvironment around the probe rather than slow insertion into the membrane. The data were rationalized with a model that allows two membrane/probe configurations with distinct microenvironments. The analysis suggests that by monitoring the equilibration pattern of Patman, inferences can be made regarding the polarity of two microenvironments occupied by the probe, the distribution of the probe among those microenvironments, and the kinetics with which they relax to equilibrium.
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Affiliation(s)
- Hannabeth Franchino
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT 84602, USA
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Laurdan spectrum decomposition as a tool for the analysis of surface bilayer structure and polarity: a study with DMPG, peptides and cholesterol. J Fluoresc 2010; 20:473-82. [PMID: 19921409 DOI: 10.1007/s10895-009-0569-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Accepted: 11/03/2009] [Indexed: 10/20/2022]
Abstract
The highly hydrophobic fluorophore Laurdan (6-dodecanoyl-2-(dimethylaminonaphthalene)) has been widely used as a fluorescent probe to monitor lipid membranes. Actually, it monitors the structure and polarity of the bilayer surface, where its fluorescent moiety is supposed to reside. The present paper discusses the high sensitivity of Laurdan fluorescence through the decomposition of its emission spectrum into two Gaussian bands, which correspond to emissions from two different excited states, one more solvent relaxed than the other. It will be shown that the analysis of the area fraction of each band is more sensitive to bilayer structural changes than the largely used parameter called Generalized Polarization, possibly because the latter does not completely separate the fluorescence emission from the two different excited states of Laurdan. Moreover, it will be shown that this decomposition should be done with the spectrum as a function of energy, and not wavelength. Due to the presence of the two emission bands in Laurdan spectrum, fluorescence anisotropy should be measured around 480 nm, to be able to monitor the fluorescence emission from one excited state only, the solvent relaxed state. Laurdan will be used to monitor the complex structure of the anionic phospholipid DMPG (dimyristoyl phosphatidylglycerol) at different ionic strengths, and the alterations caused on gel and fluid membranes due to the interaction of cationic peptides and cholesterol. Analyzing both the emission spectrum decomposition and anisotropy it was possible to distinguish between effects on the packing and on the hydration of the lipid membrane surface. It could be clearly detected that a more potent analog of the melanotropic hormone alpha-MSH (Ac-Ser(1)-Tyr(2)-Ser(3)-Met(4)-Glu(5)-His(6)-Phe(7)-Arg(8)-Trp(9)-Gly(10)-Lys(11)-Pro(12)-Val(13)-NH(2)) was more effective in rigidifying the bilayer surface of fluid membranes than the hormone, though the hormone significantly decreases the bilayer surface hydration.
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Lowry M, Fakayode SO, Geng ML, Baker GA, Wang L, McCarroll ME, Patonay G, Warner IM. Molecular Fluorescence, Phosphorescence, and Chemiluminescence Spectrometry. Anal Chem 2008; 80:4551-74. [DOI: 10.1021/ac800749v] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Mark Lowry
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, Department of Chemistry, Winston-Salem State University, Winston-Salem, North Carolina 27110, Department of Chemistry, Nanoscience and Nanotechnology Institute and the Optical Science and Technology Center, University of Iowa, Iowa City, Iowa 52242, Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale,
| | - Sayo O. Fakayode
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, Department of Chemistry, Winston-Salem State University, Winston-Salem, North Carolina 27110, Department of Chemistry, Nanoscience and Nanotechnology Institute and the Optical Science and Technology Center, University of Iowa, Iowa City, Iowa 52242, Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale,
| | - Maxwell L. Geng
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, Department of Chemistry, Winston-Salem State University, Winston-Salem, North Carolina 27110, Department of Chemistry, Nanoscience and Nanotechnology Institute and the Optical Science and Technology Center, University of Iowa, Iowa City, Iowa 52242, Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale,
| | - Gary A. Baker
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, Department of Chemistry, Winston-Salem State University, Winston-Salem, North Carolina 27110, Department of Chemistry, Nanoscience and Nanotechnology Institute and the Optical Science and Technology Center, University of Iowa, Iowa City, Iowa 52242, Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale,
| | - Lin Wang
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, Department of Chemistry, Winston-Salem State University, Winston-Salem, North Carolina 27110, Department of Chemistry, Nanoscience and Nanotechnology Institute and the Optical Science and Technology Center, University of Iowa, Iowa City, Iowa 52242, Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale,
| | - Matthew E. McCarroll
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, Department of Chemistry, Winston-Salem State University, Winston-Salem, North Carolina 27110, Department of Chemistry, Nanoscience and Nanotechnology Institute and the Optical Science and Technology Center, University of Iowa, Iowa City, Iowa 52242, Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale,
| | - Gabor Patonay
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, Department of Chemistry, Winston-Salem State University, Winston-Salem, North Carolina 27110, Department of Chemistry, Nanoscience and Nanotechnology Institute and the Optical Science and Technology Center, University of Iowa, Iowa City, Iowa 52242, Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale,
| | - Isiah M. Warner
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, Department of Chemistry, Winston-Salem State University, Winston-Salem, North Carolina 27110, Department of Chemistry, Nanoscience and Nanotechnology Institute and the Optical Science and Technology Center, University of Iowa, Iowa City, Iowa 52242, Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale,
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Sachl R, Stepánek M, Procházka K, Humpolícková J, Hof M. Fluorescence study of the solvation of fluorescent probes prodan and laurdan in poly(epsilon-caprolactone)-block-poly(ethylene oxide) vesicles in aqueous solutions with tetrahydrofurane. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:288-95. [PMID: 18044937 DOI: 10.1021/la702277t] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Steady-state and time-resolved fluorescence measurements were used to study the relaxation of the microenvironment of hydrophobic probes 6-propionyl-2-(dimethylamino)naphthalene (prodan) and 6-dodecanoyl-2-(dimethylamino)naphthalene (laurdan) in systems containing vesicles formed by the amphiphilic diblock copolymer poly(epsilon-caprolactone)-block-poly(ethylene oxide) (PCL-PEO) and water/tetrahydrofurane (THF) solvent mixtures. It was found that in case of prodan, both steady-state and time-resolved emission spectra were composed of two subspectra corresponding to the emission of prodan molecules located (i) in fairly rigid (effectively viscous) and hydrophobic domains of the vesicles close to the PCL/PEO interface and (ii) in a more polar and less viscous medium (in the bulk solution). The fraction of the emission from the more polar microenvironment increases with increasing content of THF in the system. Laurdan, in contrast to prodan, appeared to be solubilized preferentially in the hydrophobic domains up to 30 vol % of THF content, and its emission spectra changed only due to swelling of hydrophobic PCL domains by added THF. The study shows that the analysis of the time-resolved emission from a probe distributed in two media is, in principle, possible, but it is quite complex and appreciably less accurate, and the relaxation times are ill-defined averages of several processes. The bimodal or shoulder-containing time-resolved spectra have to be decomposed in pertinent time-resolved subspectra and treated separately. Another important result of the study is a piece of knowledge concerning the motion of the probe with respect to the vesicle. In the studied complex system, not only the relaxation of the solvent and reorganization of polymer segments around the fluorescent headgroup of the probe affect the emission but also a lateral motion of the probe with respect to the nanoparticle within the lifetime of the excited state contributes significantly to the relaxation and to the relatively slow time-resolved Stokes shift.
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Affiliation(s)
- Radek Sachl
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, 128 40 Prague 2, Czech Republic
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