title: Membrane surface-enhanced Raman spectroscopy for sensitive detection of molecular behavior of lipid assemblies.
abstract: The dynamic properties of phospholipid (PL) membranes (phase state and phase transition) play crucial roles in biological systems. However, highly sensitive, direct analytical methods that shed light on the nature of lipids and their assemblies have not been developed to date. Here, we describe the analysis of PL-modified Au nanoparticles (Au@PL) using membrane surface-enhanced Raman spectroscopy (MSERS) and report the properties of the self-assembled PL membranes on the Au nanoparticle. The Raman intensity per PL concentration increased by 50-170 times with Au@PL, as compared to large unilamellar vesicles (LUVs) at the same PL concentration. The phase state and phase transition temperature of the PL membrane of Au@PL were investigated by analyzing the Raman peak ratio (R = I2882/I2930). The enhancement at 714 cm(-1) (EF(714)) varied with the hydrocarbon chain length of the PLs and the assembled degree of Au@PLs. In calculation, the EF(714),assembled was estimated to be 111-142 when the distance between AuNPs was 7.0-7.5 nm, which was correlated to the speculative enhancement factor, suggesting that the assembly of the Au@PLs contributed to the MSERS.
authors.affiliation: †Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyamacho, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Keishi
authors.initials: K
authors.lastname: Suga
authors.affiliation: †Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyamacho, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Yoshida
authors.affiliation: ‡Department of Chemical Engineering, Graduate School of Engineering, Tohoku University, 6-6-07 Aoba, Aramaki-aza Aoba-ku, Sendai, Miyagi 980-8579, Japan.
authors.forename: Haruyuki
authors.initials: H
authors.lastname: Ishii
authors.affiliation: †Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyamacho, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Okamoto
authors.affiliation: ‡Department of Chemical Engineering, Graduate School of Engineering, Tohoku University, 6-6-07 Aoba, Aramaki-aza Aoba-ku, Sendai, Miyagi 980-8579, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Nagao
authors.affiliation: ‡Department of Chemical Engineering, Graduate School of Engineering, Tohoku University, 6-6-07 Aoba, Aramaki-aza Aoba-ku, Sendai, Miyagi 980-8579, Japan.
authors.forename: Mikio
authors.initials: M
authors.lastname: Konno
authors.affiliation: †Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyamacho, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Umakoshi
mesh_terms: D006046:Gold / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry; D010743:Phospholipids / Q000032:analysis* / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D013499:Surface Properties
chemical_list: D010743:Phospholipids; D006046:Gold