Effects of the pore-forming agent nystatin on giant phospholipid vesicles

► The response of individual, POPC sterol-free GUVs to nystatin was studied using phase-contrast microscopy. ► Three characteristic nystatin-related features are revealed: vesicle shape changes, transient tension pores and vesicle ruptures. ► The alteration of the area difference between lipid monolayers determines the vesicle shape changes. ► A two-stage model of the nystatin membrane permeabilization is explained by a single mechanism. ► The mutually antagonizing effects of nystatin and methanol at higher methanol volume fractions can be attributed to phospholipid interdigitation.