The component groups structure of DPPC bilayers obtained by specular neutron reflectometry

TL;DR

This study uses specular neutron reflectometry to analyze the internal component group structure of DPPC bilayers, revealing detailed structural features and fluctuations in supported and floating bilayers at different temperatures.

Contribution

It introduces a detailed component group structure model for DPPC bilayers based on neutron reflectometry data, enhancing understanding of bilayer internal organization.

Findings

Supported bilayer structure accurately modeled by SLD profile.

Floating bilayer resembles unilamellar vesicles but with higher fluctuation rates.

Temperature affects bilayer phase and internal structure.

Abstract

Specular neutron reflectometry (SNR) was measured on a system of a floating bilayer consisting of 1,2-dipalmitoyl-d62-\textit{sn}-glycero-3-phosphocholine (d62-diC16:0PC) deposited over a 1,2-dibehenoyl-\textit{sn}-glycero-3-phosphocholine (diC22:0PC) bilayer at 25 and 55 {\deg}C. The internal structure of lipid bilayers was described by a one dimensional scattering length density profile (SLDP) model, originally developed for the evaluation of small angle scattering data. The corresponding model reflectivity curves successfully describe the experimental reflectivity curves of a supported bilayer in the gel phase and a system of a floating bilayer in the liquid crystalline phase. The reflectivity data from the supported bilayer were evaluated individually and served further as an input by the data treatment of floating bilayer reflectivity curves. The results yield internal structure of a deposited and floating bilayer on the level of component groups of lipid molecules. The obtained structure of the floating d62-diC16:0PC bilayer displays high resemblance to the bilayer structure in the form of unilamellar vesicles, however, simultaneously it shows rate of fluctuations in comparison to unilamellar vesicle bilayers.