title: Using three-phase flow of immiscible liquids to prevent coalescence of droplets in microfluidic channels: criteria to identify the third liquid and validation with protein crystallization.
abstract: This manuscript describes the effect of interfacial tensions on three-phase liquid-liquid-liquid flow in microfluidic channels and the use of this flow to prevent microfluidic plugs from coalescing. One problem in using microfluidic plugs as microreactors is the coalescence of adjacent plugs caused by the relative motion of plugs during flow. Here, coalescence of reagent plugs was eliminated by using plugs of a third immiscible liquid as spacers to separate adjacent reagent plugs. This work tested the requirements of interfacial tensions for plugs of a third liquid to be effective spacers. Two candidates satisfying the requirements were identified, and one of these liquids was used in the crystallization of protein human Tdp1 to demonstrate its compatibility with protein crystallization in plugs. This method for identifying immiscible liquids for use as a spacer will also be useful for applications involving manipulation of large arrays of droplets in microfluidic channels.
authors.affiliation: Department of Chemistry and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, USA.
authors.forename: Delai L
authors.initials: DL
authors.lastname: Chen
authors.forename: Liang
authors.initials: L
authors.lastname: Li
authors.forename: Sebastian
authors.initials: S
authors.lastname: Reyes
authors.forename: David N
authors.initials: DN
authors.lastname: Adamson
authors.forename: Rustem F
authors.initials: RF
authors.lastname: Ismagilov
mesh_terms: D003460:Crystallization; D015394:Molecular Structure; D011506:Proteins / Q000737:chemistry*
chemical_list: D011506:Proteins