title: Di-8-ANEPPS emission spectra in phospholipid/cholesterol membranes: a theoretical study.
abstract: We have investigated the effects of explicit molecular interactions and the membrane dipole potential on the absorption and emission spectra of a widely used fluorescent probe, di-8-ANEPPS, in a dipalmitoylphosphatidylcholine (DPPC) and a mixed DPPC/cholesterol membrane bilayer. Ground-state and excited-state geometries were calculated with the complete active space self-consistent field (CASSCF) method. Interactions with up to 260 atoms of the membrane bilayer were explicitly incorporated using a decoupled quantum mechanics/molecular mechanics (QM/MM) approach, utilizing recent advances in time-dependent density functional theory (TDDFT). We find that no specific molecular interactions affect the fluorescence of di-8-ANEPPS; rather, the magnitude of the membrane dipole potential is key to the shifts observed in both of the two lowest excited states.
authors.affiliation: School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Robinson
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Besley
authors.forename: Paul
authors.initials: P
authors.lastname: O'Shea
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Hirst
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry*; D002784:Cholesterol / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008962:Models, Theoretical; D056004:Molecular Dynamics Simulation; D011726:Pyridinium Compounds / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: C089669:1-(3-sulfonatopropyl)-4-(beta-(2-(di-n-octylamino)-6-naphthyl)vinyl)pyridinium betaine; D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D011726:Pyridinium Compounds; D015060:1,2-Dipalmitoylphosphatidylcholine; D002784:Cholesterol