Dresden 2020 – scientific programme

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BP: Fachverband Biologische Physik

BP 9: Poster II

BP 9.20: Poster

Monday, March 16, 2020, 17:30–19:30, P2/2OG

Fusogenic Liposomes are Intrinsically Tensed — •Laura Schmitt, Rudolf Merkel, and Agnes Cziszár — Insitute of Complex Systems 7: Biomechanics, Forschungszentrum Jülich, Germany

Liposomes are popular carriers for drug molecules, which enter cells either by endocytosis or by fusion of membranes. The former process is slow and significant drug degradation occurs, the latter is most often mediated by fusogenic proteins and is thus costly and complex. Spurred by this dilemma, fusogenic liposomes were introduced by the last author of this contribution. These liposomes are formed from a ternary lipid mixture and fuse rapidly with cell membranes. Here, we explored basic physical properties of fusogenic membranes.

Therefore, GUVs (giant unilamellar vesicles) were prepared from the fusogenic lipid mixture. We examined their elastic properties using fluorescence microscopy and micropipet aspiration. Additionally, AFM compression was used.

Contrary to control GUVs, fusogenic GUVs showed no thermal fluctuations. Hence, we focused on tension-induced area dilation. We found that very high suction pressures are necessary to deform fusogenic GUVs, the resulting apparent area increases were exceptionally high. Furthermore, fusogenic GUVs could withstand much larger forces than control GUVs when compressed between parallel plates.

This behavior was attributed to an intrinsic membrane tension. We assume that this tension is caused by a coexistence of a non-lamellar lipid phase with the usual lipid bilayer. This non-lamellar phase presumably acts as a membrane reservoir.