title: Heterogeneous rotational diffusion of a fluorescent probe in lipid monolayers.
abstract: The rotational correlation time of the lipid probe 1-palmitoyl-2-{6-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]hexanoyl}-sn-glycero-3-phosphocholine (NBD-PC) is measured using fluorescence anisotropy for two lipid species. We measure the rotational diffusion in a monolayer of 1,2-Didecanoyl-sn-glycero-3-phosphocholine (DPPC) which displays a phase transition at room temperature from the liquid-expanded to the liquid-condensed phase. The constant rotational diffusion of the probe throughout the phase transition reflects the measurement of dynamics in only the liquid-expanded phase. We contrast the dynamic changes during this phase coexistence to the continuous density increase observed in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) at room temperature. We observe a non-exponential decay of the probe diffusion consistent with heterogeneity of the orientational dynamics.
authors.affiliation: Physics Department, Wesleyan University , Middletown, Connecticut 06459, USA.
authors.forename: Neda
authors.initials: N
authors.lastname: Dadashvand
authors.affiliation: Physics Department, Wesleyan University , Middletown, Connecticut 06459, USA.
authors.forename: LaNell A
authors.initials: LA
authors.lastname: Williams
authors.affiliation: Physics Department, Wesleyan University , Middletown, Connecticut 06459, USA.
authors.forename: Christina M
authors.identifier: 0000-0002-5937-0511
authors.initials: CM
authors.lastname: Othon