title: Binding of a cationic phenazinium dye in anionic liposomal membrane: a spectacular modification in the photophysics.
abstract: Interaction of a cationic phenazinium dye, phenosafranin (PSF), with the anionic liposomal vesicle/bilayer of dimyristoyl-L-alpha-phosphatidylglycerol (DMPG) has been demonstrated using steady state and time resolved fluorescence and fluorescence anisotropy techniques. The charge transfer emission spectrum of PSF shows a dramatic modification in terms of fluorescence yield together with an appreciable hypsochromic shift in the lipid environment. The blue shift indicates a lowering in polarity inside the vesicle as compared to that in bulk water. The fluorescence and fluorescence quenching studies and micropolarity determination reveal that the cationic fluorophore has a profound binding interaction with the anionic DMPG membrane. Anisotropy study indicates the imposition of a motional restriction on the probe inside the bilayer. The electrostatic interaction between the cationic dye and the anionic lipid membrane has been argued to be the reason behind all these observations. The results could be useful in analyzing membrane organization and heterogeneity in natural membranes exploiting PSF or alike compounds as fluorescent probes.
authors.affiliation: Department of Chemistry, Jadavpur University, Raja S. C. Mullick Road, Kolkata 700032, India.
authors.forename: Debosreeta
authors.initials: D
authors.lastname: Bose
authors.forename: Debanjana
authors.initials: D
authors.lastname: Ghosh
authors.forename: Priyanka
authors.initials: P
authors.lastname: Das
authors.forename: Agnishwar
authors.initials: A
authors.lastname: Girigoswami
authors.forename: Deboleena
authors.initials: D
authors.lastname: Sarkar
authors.forename: Nitin
authors.initials: N
authors.lastname: Chattopadhyay
mesh_terms: D000042:Absorption; D000838:Anions / Q000737:chemistry; D016880:Anisotropy; D001965:Bromides / Q000737:chemistry; D002412:Cations / Q000737:chemistry; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D010619:Phenazines / Q000737:chemistry*; D010715:Phosphatidylglycerols / Q000737:chemistry; D013997:Time Factors
chemical_list: D000838:Anions; D001965:Bromides; D002412:Cations; D005456:Fluorescent Dyes; D008081:Liposomes; D010619:Phenazines; D010715:Phosphatidylglycerols; C011977:phenosafranine; C002773:dimyristoylphosphatidylglycerol