(142b) Chiral Rheology of Condensed DPPC Domains

We present the asymmetric responses of condensed phase dipalmitoylphosphatidylcholine (DPPC) monolayers due to clockwise and counterclockwise deformations. The phospholipid, especially DPPC, forms condensed grainy liquid crystal monolayer, whose individual grains are chiral: due to tilt of tail group at the interface and a chiral point within the molecular structure, bio-derived DPPC, R enantiomer, grains curl in counterclockwise direction while S-DPPC , made by only synthetically, curls in clockwise direction. By applying constant stress to the interlocked condensed domains of R DPPC at condensed phase, we show that the strain responses are asymmetric: deformations are easier in clockwise direction than counterclockwise direction. In addition, we manipulate the degree of chirality of DPPC grains by adding racemic DPPC which contains no chiral properties, and we show that this asymmetry of strains decreases as adding more racemic DPPC to R DPPC. We conclude that this chirality of DPPC domains leads to a chiral viscoelastic responses.