Title : 『Active microrheology of phospholipid monolayers at the air/water interface』

Speaker : Dr. Siyoung Choi (Dept. of Chemical Engineering, UC Santa Barbara)

Date : 28 November, 2011 (Mon) 10:30AM

Place : Seminar room #1 (Room 1101) @W1-3 Bldg.

Abstract :

Phospholipid monolayers (with and without cholesterol) at the air-water interface serve as model systems for various biological interfaces, e.g. lung surfactant layers and outer leaflets of cell membranes. Although the dynamical (viscoelastic) properties of these interfaces may play a key role in stability, dynamics and function, the relatively weak rheological properties of most such monolayers have rendered their study difficult or impossible. Using a novel technique we have recently developed, we measure the viscoelastic properties of phospholipid DPPC monolayers, both with and without cholesterol, at the air-water interface. Notably, our apparatus enable direct interfacial visualization during the measurement, which enables us to relate the observed interfacial structure and dynamics to the measured viscoelastic behavior. Our experiments reveal that such monolayers have a far richer dynamical response than has been previously reported. In particular, we demonstrate viscoelasticity, history-dependence, aging, yielding and a surprisingly long relaxation time. The influence of cholesterol upon these dynamic structures—and thus rheology—is visualized, measured and modeled.

※ For international students, attendance of this seminar will be considered as attendance of department seminar during regular semester.