Mechanical properties of protoamine-induced vesicles

The change in the mechanical properties was an indicator to understand the effect of the agents on the biological
membranes. The vesicles were prepared with dipalmitoylphosphatidylcholine (DPPC) and protoamine at their
desired ratio and exposed to the approaching probe of the atomic force microscope (AFM). The movement of the
probe was analyzed with the Hertzian model to estimate Young’s modulus and Bending modulus. The properties
became lower with the higher ratio of protoamine to DPPC, but were saturated at 0.5 of the ratio. These results
appear to be the basis for the antimicrobial activity associated with protoamine, i.e. cellular penetration, on the
physical properties of cell membranes.