A.G. POPESCU*, D. POPESCU**, S. ION**, B. AMUZESCU***

*Department of Computer Sciences, IT CORE SRL, 10, Garoafei St, Bucharest 051235, Romania
**Department of Mathematical Modelling in Life Sciences, Institute of Mathematical Statistics and Applied Mathematics, Romanian Academy, 13, 13 Septembrie Av., Bucharest 050911, Romania,
***Department of Anatomy, Animal Physiology and Biophysics, Center of Neurobiology and Molecular Physiology, Faculty of Biology, University of Bucharest, 91–95, Splaiul Independenţei Bucharest 050095, Romania

Abstract. An unilamellar liposome filled with an aqueous solution of an impermeant solute was introduced into a hypotonic aqueous medium. Because of the mechanical tension induced by osmotic flow, the vesicle swells up to a critical size, when suddenly a transbilayer pore appears. A part of the intravesicular material leaks out through this pore, and the liposome membrane relaxes and eventually recovers. The swelling begins again, and the liposome experiences a cyclic process. For this reason we have named it a pulsatory liposome. In this paper we derived the differential equations of both the vesicle and the pore dynamics. We also computed all the parameters of the second part of a duty cycle (pore lifetime, number of cycles, the duration of vesicle activity, the amount of material leaked out during a cycle) for a particular case. The condition to program a vesicle to work for n consecutive cycles was deduced.
Key words: Osmotic gradient, stretched vesicle, pulsatory vesicle, drug release biocontroller.

Corresponding author’s e-mail: popescu1947@yahoo.com

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