Light-driven formation and rupture of droplet bilayers.
We demonstrate the optical manipulation of nanoliter aqueous droplets containing surfactant or lipid molecules and immersed in an organic liquid using near-infrared light. The resulting emulsion droplets are manipulated using both the thermocapillary effect and convective fluid motion. Droplet-pair interactions induced in the emulsion upon optical initiation and control provide direct observations of the coalescence steps in intricate detail. Droplet-droplet adhesion (bilayer formation) is observed under several conditions. Selective bilayer rupture is also realized using the same infrared laser. The technique provides a novel approach to studying thin film drainage and interface stability in emulsion dynamics. The formation of stable lipid bilayers at the adhesion interface between interacting water droplets can provide an optical platform on which to build droplet-based lipid bilayer assays. The technique also has relevance to understanding and improving microfluidics applications by devising Petri dish-based droplet assays requiring no substrate fabrication.
Dixit
Sanhita S
SS
Molecular Physics Laboratory, SRI International, 333 Ravenswood Avenue, Menlo Park, California 94025, USA. sanhita.dixit@sri.com
Kim
Hanyoup
H
Vasilyev
Arseny
A
Eid
Aya
A
Faris
Gregory W
GW
D005233:Fatty Alcohols / Q000737:chemistry; D005994:Glycerophosphates / Q000737:chemistry; D007259:Infrared Rays; D008027:Light; D008051:Lipid Bilayers / Q000737:chemistry*; D008899:Mineral Oil / Q000737:chemistry; D010767:Phosphorylcholine / Q000737:chemistry; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry; D014867:Water / Q000737:chemistry
D005233:Fatty Alcohols; D005994:Glycerophosphates; D008051:Lipid Bilayers; D013501:Surface-Active Agents; D014867:Water; D010767:Phosphorylcholine; D012967:Sodium Dodecyl Sulfate; D008899:Mineral Oil; C029383:n-decyl alcohol; C029620:alpha-glycerophosphoric acid