Active microrheology and simultaneous visualization of sheared phospholipid monolayers

S. Q. Choi, S. Steltenkamp, J. A. Zasadzinski, T. M. Squires

Research output: Contribution to journalArticlepeer-review

91 Scopus citations

Abstract

Two-dimensional films of surface-active agents - from phospholipids and proteins to nanoparticles and colloids - stabilize fluid interfaces, which are essential to the science, technology and engineering of everyday life. The 2D nature of interfaces present unique challenges and opportunities: coupling between the 2D films and the bulk fluids complicates the measurement of surface dynamic properties, but allows the interfacial microstructure to be directly visualized during deformation. Here we present a novel technique that combines active microrheology with fluorescence microscopy to visualize fluid interfaces as they deform under applied stress, allowing structure and rheology to be correlated on the micron-scale in monolayer films. We show that even simple, single-component lipid monolayers can exhibit viscoelasticity, history dependence, a yield stress and hours-long time scales for elastic recoil and aging. Simultaneous visualization of the monolayer under stress shows that the rich dynamical response results from the cooperative dynamics and deformation of liquid-crystalline domains and their boundaries.

Original languageEnglish (US)
Article number312
JournalNature communications
Volume2
Issue number1
DOIs
StatePublished - 2011

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