Osmotic critical phenomena of semipermeable unilamellar vesicles

Motivated by biological protocols that require transfer of large pieces of DNA into cells, we here review several aspects of osmotic swelling and lysis of semipermeable unilamellar vesicles. Swelling involves a continuous phase transition from a fluctuating flaccid state to a maximum volume turgid state, without a divergent correlation length and with exponents that violate the hyperscaling relation. At the point of rupture, fluctuation contributions to surface and line tensions can support or suppress thermal generation of stable pores. The transfer of water through the membrane in response to osmotic pressure changes can compress, swell, rupture, and fuse vesicles: semipermeable unilamellar vesicles exhibit diverse osmotic critical phenomena.