Structural properties and Raman spectroscopy of lipid Langmuir monolayers at the air-water interface

TL;DR

This study investigates the structural organization and vibrational properties of lipid monolayers at the air-water interface using spectroscopy, microscopy, and SERS, revealing interactions between surfactants and phospholipids.

Contribution

It provides new insights into the molecular interactions and Raman enhancement mechanisms in lipid monolayers through combined spectroscopic and microscopic analysis.

Findings

Strong interaction between surfactant headgroups and silver particles enhances Raman signals.

Mixing phospholipids with surfactants enables vibrational analysis via SERS.

Surface pressure-area isotherms reveal monolayer organization and domain structures.

Abstract

Spectra of octadecylamine (ODA) Langmuir monolayers and egg phosphatidylcholine (PC)/ODA-mixed monolayers at the air-water interface have been acquired. The organization of the monolayers has been characterized by surface pressure-area isotherms. Application of polarized optical microscopy provides further insight in the domain structures and interactions of the film components. Surface-enhanced Raman scattering (SERS) data indicate that enhancement in Raman spectra can be obtained by strong interaction between headgroups of the surfactants and silver particles in subphase. By mixing ODA with phospholipid molecules and spreading the mixture at the air-water interface, we acquired vibrational information of phospholipid molecules with surfactant-aided SERS effect.