Speaker: Christine DeWolf, Department of Chemistry and Biochemistry, Concordia University
Title: Structure and organization in interfacial films: implications for health nanotechnology and the environment
Date, Time and Place: Friday February 1, 2019. 10 am , TB 202
Langmuir monolayers are formed at the air-water interface and are frequently used to pre-organize molecular and particle films for deposition onto solid substrate (Langmuir-Blodgett films) and as models of biological membranes. Within these films there is a rich phase behaviour that has implications for both biological and material functionality. In this seminar the interaction of charged nanoparticles with lung surfactant will be presented. Lung surfactant comprises a lipid-protein film that coats the air-lung interface of the alveoli. Its function properties depend on a complex phase behaviour governed by the continual compression and expansion of the film. The inhalation of ultrafine particulate (< 100 nm) has both been identified as a health risk and yet at the same time nanocarriers are proposed for drug delivery to the lungs. In this work, structural information obtained from surface x-ray scattering and morphological data from AFM and Brewster angle microscopy are used to assess the impact of inhaled nanoparticulate on the functional properties of lung surfactant. We find that charged nanoparticles impact the film structure and morphology at concentrations orders of magnitude below those commonly reported in the literature. Moreover, while much of the lung surfactant field has focused on anionic nanoparticles, we find that at these low concentrations, cationic nanoparticles have a greater impact. The cationic nanoparticles induce a induce similarities in the structural and morphological progressions of lipid-only films to those observed for films containing cationic SP-B protein, highlighting that a possible role of cationic species may include condensation of anionic lipids and facilitation of reservoir formations. We find that the amount of cationic species must be tightly regulated in lung surfactant with implications for design parameters of engineered NPs biomedical applications, synthetic lung surfactant formulations and occupational/environmental health regulations.