Thermophoretic migration of vesicles depends on mean temperature and head group chemistry

A number of colloidal systems, including polymers, proteins, micelles and hard spheres, have been studied in thermal gradients to observe and characterize their driven motion. Here we show experimentally the thermophoretic behaviour of unilamellar lipid vesicles, finding that mobility depends on the mean local temperature of the suspension and on the structure of the exposed polar lipid head groups. By tuning the temperature, vesicles can be directed towards hot or cold, forming a highly concentrated region. Binary mixtures of vesicles composed of different lipids can be segregated using thermophoresis, according to their head group. Our results demonstrate that thermophoresis enables robust and chemically specific directed motion of liposomes, which can be exploited in driven processes.This work was supported by EPSRC (grant number EP/J017566/1). L.D.M. acknowledges support from the Oppenheimer Fund, Emmanuel College Cambridge, the Leverhulme Trust and the Isaac Newton Trust through an Early Career Fellowship