title: Disperse Orange 3 as a resonance Raman probe for measuring membrane order.
abstract: Resonance Raman spectra of azobenzene derivatives were examined in the presence of lipid membranes to find a probe that can distinguish different membrane phases. The NO2 symmetric stretching band of 4-(4-nitrophenylazo)aniline, also known as Disperse Orange 3 (DO3), is downshifted by about 4 cm(-1) on the phase transition of phosphatidylcholine membranes from the liquid crystalline to the gel phase. A comparable downshift also occurs when DO3 is bound to cholesterol-containing membranes in the liquid-ordered phase. Our results demonstrate that Raman spectrum of DO3 is a unique tool for measuring the molecular order of lipids in membranes.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Tohoku University, Aobayama, Sendai 980-8578, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Numakura
authors.affiliation: Graduate School of Pharmaceutical Sciences, Tohoku University, Aobayama, Sendai 980-8578, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Miura
keywords: CT-B, B subunit of cholera toxin; DMPC, 1,2-dimyristoyl-sn-glycero-3-phosphocholine; DO3, Disperse Orange 3 [4-(4-nitrophenylazo)aniline]; DPPC, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine; Disperse Orange 3; Membrane microdomains; Membrane order; POPC, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine; Raman spectroscopy; Resonance Raman probe; Tm, main phase transition temperature