Analytical Sciences

Abstract − Analytical Sciences, 29(9), 865 (2013).

Tip-enhanced Raman Spectroscopy of Lipid Bilayers in Water with an Alumina- and Silver-coated Tungsten Tip
Atsushi NAKATA,* Tomonori NOMOTO,* Taro TOYOTA,** and Masanori FUJINAMI*
*Department of Applied Chemistry and Biotechnology, Chiba University, 1-33 Yayoi, Inage, Chiba 263–8522, Japan
**Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153–8902, Japan
Tip-enhanced Raman spectroscopy (TERS) of supported phospholipid bilayers in an aqueous environment is discussed in this paper. Two bilayer membranes were examined: 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). We fabricated alumina- and silver-coated tungsten tips that are very robust in water. There was a large time-dependence in the TERS spectra for the DOPC bilayers, whereas no such time-dependence was observed in the DPPC bilayer spectra under the probe tip. The spectral changes of DOPC bilayers are discussed in terms of the fluidity of the liquid crystalline phase. Time-resolved TERS thus has the potential to characterize inhomogeneity and diffusion in fluidic phospholipid bilayer membranes.