Determination of the Porphyrin Orientation Distribution in Langmuir Monolayers by Polarized Epifluorescence

Abstract

A new technique for the determination of the orientation distribution of a porphyrin within a Langmuir monolayer, in terms of the mean tilt angle relative to the monolayer normal and the width, is described. The technique utilizes the measurement of polarized fluorescence, excited with the electric field both parallel and perpendicular to the monolayer plane. The main difference between this technique and the existing ones [Fraaije et al.,

Combination of Polarized TIRF and ATR Spectroscopies for Determination of the Second and Fourth Order Parameters of Molecular Orientation in Thin Films and Construction of an Orientation Distribution Based on the Maximum Entropy Method

“…The case of a circular absorber has been reported by Tronin et al; 33 however, there are errors 67,68 in their auxiliary eqs 12 and 13 that preclude their use for the derivation of the order parameters. In the molecular coordinate system (x′-y′-z′), the absorption dipole for a circular absorber can be described as follows: and the emission dipole: with where γ and account for the in-plane and out-of-plane depolarization, respectively.…”

Fluorescence Imaging of Two-Photon Linear Dichroism: Cholesterol Depletion Disrupts Molecular Orientation in Cell Membranes

“…Another property that is fundamental for membraneprotein function is the orientation of the protein relative to the membrane (Doucey et al, 2004;Mitra et al, 2004). Several studies of anisotropy of molecules in macroscopically oriented lipid environments have been reported, including studies of: 1), Lipid bilayers or Langmuir-Blodgett films that are mounted at an angle from the incoming beam allowing measurements of both absorbance and fluorescence (Karolin et al, 1994;Edmiston et al, 1996;Tronin et al, 2000;Lopes and Castanho 2004); 2), Polarized fluorescence imaging of vesicles or cell membranes (Axelrod 1979;Blackman et al, 1996;Sund et al, 1999;Rocheleau et al, 2003); 3), Linear dichroism (LD) of vesicles that are deformed in a laminar flow creating an experimental orientation axis (Ardhammar et al, 1998;Brattwall et al, 2003); and 4), The effect of refractive index on radiative decay rate of probes orientated in lipid vesicles (Toptygin and Brand 1993;Krishna and Periasamy 1998).…”

Analysis of Urinary Porphyrins by High Performance Liquid Chromatography-Electrospray Ionization Mass Spectrometry

“…In the early years, solvent fractionation methods were usually performed, [19,20] which were laborious and imprecise in the separation of porphyrins. More recently, a number of separation methods have been developed and applied for the analysis of porphyrins in biological samples, including gas chromatography (GC), [21] flow-injection analysis (FIA), [22] thin-layer chromatography (TLC), [23,24] high performance liquid chromatography (HPLC), [25][26][27] and capillary electrophoresis (CE). [28,29] HPLC has obtained considerable attention for the porphyrin separation [30] with various detection techniques including immunoassay, [31] inductive coupled plasma-atomic emission spectrum (ICP-AES), [32] electrochemical mode, [33,34] and the conventional ultraviolet visible (UV-Vis) detector.…”