title: Active rheology of phospholipid vesicles.
abstract: Optical tweezers are used to manipulate the shape of artificial dioleoyl-phosphatidylcholine (DOPC) phospholipid vesicles of around 30 μm diameter. Using a time-shared trapping system, a complex of traps drives oscillations of the vesicle equator, with a sinusoidal time dependence and over a range of spatial and temporal frequencies. The mechanical response of the vesicle membrane as a function of the frequency and wavelength of the driving oscillation is monitored. A simple model of the vesicles as spherical elastic membranes immersed in a newtonian fluid, driven by a harmonic trapping potential, describes the experimental data. The bending modulus of the membrane is recovered. The method has potential for future investigation of nonthermally driven systems, where comparison of active and passive rheology can help to distinguish nonthermal forces from equilibrium fluctuations.
authors.affiliation: Cavendish Laboratory and Nanoscience Centre, University of Cambridge, Cambridge CB3 0HE, United Kingdom.
authors.forename: Aidan T
authors.initials: AT
authors.lastname: Brown
authors.forename: Jurij
authors.initials: J
authors.lastname: Kotar
authors.forename: Pietro
authors.initials: P
authors.lastname: Cicuta
mesh_terms: D002462:Cell Membrane / Q000737:chemistry; D004548:Elasticity; D009038:Motion; D052898:Optical Tweezers; D010713:Phosphatidylcholines / Q000737:chemistry*; D012212:Rheology; D053835:Unilamellar Liposomes / Q000737:chemistry*; D014783:Viscosity
chemical_list: D010713:Phosphatidylcholines; D053835:Unilamellar Liposomes; C017251:1,2-oleoylphosphatidylcholine