Nanovectors for drug delivery: Long-lived pore dynamics for swelling liposomes

A liposome is a spherical, bilayer vesicle separating the interior volume containing an aqueous solution, from an exterior suspension. A fundamental practical application provides the liposome used as vehicles for drug delivery. In this case, liposomes are designed to contain a specific drug or a gene needed to fight the disease. If a vesicle containing high internal solute concentration is placed inside a dilute solution, the osmotic flux of solvent into the interior can lead to its rupture or a formation of pores. Such pores can be long-lived pores or short-lived pores suddenly closing after their formations. Long-lived pores lead to a well controlled drug delivery. In this paper, we show that the existence of long-lived pores is completely conditioned only by the pore dynamics, and that the long-lived pore dynamics is highly stable because sustained by a limit cycle. Moreover, we calculate analytically the frequency of a long-lived pore making use of the He's variational method.