Speaker
Description
The popularity of small-angle scattering for the study of biologically relevant materials stems from the fact that it provides detailed information on the size, shape, and conformation of molecular assemblies in solutions. Unilamellar vesicles formed by phospholipids serve as models of biological membranes and drug carriers. SANS data treated by using the vesicle model provide information about structural parameters such as the diameter of the vesicle, the thickness of the lipid bilayer (and/or its structural parts), the polydispersity of the system, etc., while knowing neutron scattering length densities (NSLD) of the lipid molecules and the used solvent. The other way to study membrane systems is based on neutron diffraction from a stack of planar lipid bilayers deposited on a silica wafer and hydrated by vapor. Model-free neutron diffraction data analysis provides high-accuracy structural parameters such as the thickness of the lipid bilayer, the head-to-head distance, and the water distribution profile. The advantages and limitations of both approaches will be illustrated with the study of a complex biological system: lung surfactant.
Lung surfactant (LS) is a mixture of lipids (~90%) and ~10% of specific surfactant-associated proteins. LS lines the interior of the lung alveoli and acts to lower interfacial tension. The absence of LS due to prematurity or its damage is treated with exogenous lung surfactant (ELS) in neonatal medicine and also in ventilated patients with Covid-19 disease in experimental treatment. The clinically used substitute surfactant Curosurf®, a porcine lung tissue extract, and a protein-free lipid mixture were used as ELS in the study. The effect of selected drugs from the group of antibiotics and corticosteroids on the structure of ELS will be discussed. Molecular dynamics simulation was used to complete the selected experimental findings. The findings will be discussed in the context of medical application. A more recent trend involves the idea that ELS could also be used as a delivery vehicle for pulmonary therapeutics.
Acknowledgments
This work was funded by the VEGA project 1/0305/24. SANS experiments were performed on the PAXY instrument at LLB Saclay. SAND experiments were performed on the D16 instrument, ILL Grenoble, DOI: 10.5291/ILL-DATA.8-02-1032.
