Pulsatory liposome-a two-stroke bionic biomicroengine

In this paper, we have considered the problem of a pulsatory lipid vesicle. Under positive osmotic stress a giant lipid vesicle swells up to a critical diameter, when suddenly a transbilayer pore appears if the swelling process is slowly enough. A part of the intracellular material comes out of the cell through this transmembrane pore and the liposome membrane relaxes and finally, it recovers. The pore increases in the first part of its evolution, then decreases, and finally it closes. The both simultaneous dynamics processes described above start again and so on. The vesicle evolution is a cyclic process and the vesicle becomes a pulsatory one. Here we will obtain the differential equations of both the vesicle and the pore dynamics. Also, we will analyse characteristic parameters of the periodic process (swelling time, pore lifetime, number of cycles, the lengthtime of vesicle activity, material quantity leaked out during a cycle). Also, we present the condition to programme a n-cycles working vesicle.