Influence of plasma treatment on the structure and function of lipids

Abstract

The membrane of both pro- and eukaryotic cells is the cell’s interface with the environment. It is the first interaction site of any substance that is externally applied, including reactive species in the liquid cell environment created by plasma medical treatments. Therefore, the liquid surrounding the cell is, due to its influence on the chemical paths, an important mediator for plasma-borne reactive species, and the cellular membrane is their primary target structure. A cellular membrane consists, according to the Singer–Nicolson model, of a lipid bilayer with embedded proteins. Here, we describe experiments of plasma treatments of lipids and liposomal model membranes. The investigations show membrane activity of plasmaborne reactive species against lipids and lipid structures. The methods applied are Raman microscopy and chromophore-based light spectroscopy. Results of dynamic light scattering (DLS) and fluorophore-based assays show that, during the applied plasma treatment, neither macroscopic collapse of the lipid superstructure nor liposome fusion was observed. Raman spectroscopy reveals increased fluidity of lipid layers due to plasma treatment. The results are discussed based on our observations and published results. We propose a detailed molecular mechanism for the formation of lesions that allow a “self-mediated in- and efflux” of plasmaborne reactive species and cell signaling molecules. Resulting consequences for cellular membranes and the cell as a whole are discussed.