Abstract - Stogiannidis

In this study, we examine the effect of microgravity on the membrane fluidity of giant unilamellar vesicles (GUVs) made of DOPC and Cholesterol. GUVs are prepared using electroformation technique, during which a thin film of lipids is deposited on a conductive glass substrate while the application of AC electric field accelerates the swelling of the lipid film. We first study the fluidity of the vesicles over a range of DOPC/Cholesterol ratios using Fluorescence Recovery After Photobleaching (FRAP): a disk shaped area of the vesicle is bleached using a laser for a short amount of time and the fluidity is computed from the time of fluorescence-recovery time. The same fluidity also is investigated by means of fluorescence polarization anisotropy (FPA) technique, where the intensity of the sample’s fluorescence emission is measured along two orthogonal polarization axes. The latter method can be implemented under microgravity conditions. We report a significant fluidity changes in microgravity conditions, where the vesicles display approximately 20% higher membrane fluidity compared to those measured on the ground. Our findings provide valuable insights on the cells’ behavior in zero-gravity conditions and more specifically about the absorption of pharmaceuticals in the human body. 

Georgios Stogiannidis1, Paulina Blair1,3, Laura Alvarez2, Thomas Voigtmann1,3, and Ivo Buttinoni1 — 1 Institute of Experimental Colloidal Physics, HHU - Düsseldorf, Germany — 2 Soft BioColloids Group, CRPP - Bordeaux, France — 3 Institute of Materials Physics in Space, DLR - Köln, Germany