title: Location, dynamics and solvent relaxation of a Nile Red-based phase-sensitive fluorescent membrane probe.
abstract: Fluorescent membrane probes offer the advantage of high sensitivity, suitable time resolution, and multiplicity of measurable parameters, and provide useful information on model and cell membranes. In this paper, we have explored the location, dynamics, and solvent relaxation characteristics of a novel Nile Red-based phase-sensitive probe (NR12S). Unlike Nile Red, NR12S enjoys unique orientation and location in the membrane, and is localized exclusively in the outer leaflet of the membrane bilayer. By analysis of membrane depth using the parallax approach, we show that the fluorescent group in NR12S is localized at the membrane interface, a region characterized by slow solvent relaxation. Our results show that NR12S exhibits REES (red edge excitation shift), consistent with its interfacial localization. More interestingly, REES of NR12S displays sensitivity to the membrane phase. In addition, fluorescence emission maximum, anisotropy, and lifetime of NR12S are dependent on the membrane phase. We envision that NR12S may prove to be a useful probe in future studies of complex natural membranes.
authors.affiliation: CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India.
authors.forename: Roopali
authors.initials: R
authors.lastname: Saxena
authors.affiliation: CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Shrivastava
authors.affiliation: CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India.
authors.forename: Sourav
authors.initials: S
authors.lastname: Haldar
authors.affiliation: Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, 74, Route du Rhin, 67401 Illkirch Cedex, France.
authors.forename: Andrey S
authors.initials: AS
authors.lastname: Klymchenko
authors.affiliation: CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India. Electronic address: amit@ccmb.res.in.
authors.forename: Amitabha
authors.initials: A
authors.lastname: Chattopadhyay
mesh_terms: D005456:Fluorescent Dyes / Q000032:analysis / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008422:Materials Testing; D008560:Membrane Fluidity; D010078:Oxazines / Q000032:analysis* / Q000737:chemistry*; D044367:Phase Transition; D012997:Solvents / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D010078:Oxazines; D012997:Solvents; C044808:nile red
keywords: Fluorescent membrane probe; Liquid-ordered phase; Membrane penetration depth; NR12S; Nile Red; REES