Quantitative estimation of membrane tension in a GUV in a buffer containing a physiological ion concentration

    Samiron et al have published the paper entitled with “Membrane tension in negatively charged lipid bilayers in a buffer under osmotic pressure” (J. Phys. Chem. B. 124, 5588-5599, 2020 [Abstract]. In this paper, we succeeded in determining quantitatively the membrane tension in giant unilamellar vesicles (GUVs) in a buffer containing a physiological ion concentration under osmotic pressure.  The experimentally determined values of the membrane tension agree with the theoretical values within experimental errors. So far, to apply membrane tension to a GUV, the micropipette aspiration method has been used. However, if a pore is induced in the GUV membrane by external forces and antimicrobial peptides in the GUV membrane, the GUV is immediately aspirated into the micropipette, and thus, we cannot observe the GUV during and after the pore formation. Therefore, we cannot get information on the time evolution of pores and the characteristics of the pores. In contrast, if we apply membrane tension by osmotic pressure, we can observe the GUV during and after pore formation. Therefore, the osmotic pressure method has an advantage in the investigation on the effect of membrane tension on various pore formations in the GUV membrane over the micropipette aspiration method.