The data describes: - preparation of polymer vesicles with encapsulated colistin (size distributions by dynamic light scattering, zeta potentials, cryo-electron microscopy images, fluorescence intensity of vesicles, containing or not labeled colistin, fluorescence intensity for determination of encapsulation efficiency of colistin via fluorescamine assay) - antibacterial activity (minimum inhibitory concentrations for test vesicles, control vesicles, and control colistin, prevention of biofilm formation through spectrophotometric evaluation of biomass via crystal violet staining for the same controls, leakage of cytoplasmic components via absorbance measurements at 260 and 280 nm for the same controls, minimum inhibitory concentrations for test vesicles and control colistin from serial passage to sub-inhibitory concentrations) - fluorescence intensity of 2',7'-dichlorodihydrofluorescein diacetate for determination of reactive oxygen species - surface area/pressure isotherms determined on a model phospholipid monolayer consisting of phosphatidylethanolamine:phosphatidylglycerol = 1:2 via a Langmuir trough