title: Mixing crowded biological solutions in milliseconds.
abstract: In vitro studies of biological reactions are rarely performed in conditions that reflect their native intracellular environments where macromolecular crowding can drastically change reaction rates. Kinetics experiments require reactants to be mixed on a time scale faster than that of the reaction. Unfortunately, highly concentrated solutions of crowding agents such as bovine serum albumin and hemoglobin that are viscous and sticky are extremely difficult to mix rapidly. We demonstrate a new droplet-based microfluidic mixer that induces chaotic mixing of crowded solutions in milliseconds due to protrusions of the microchannel walls that generate oscillating interfacial shear within the droplets. Mixing in the microfluidic mixer is characterized, mechanisms underlying mixing are discussed, and evidence of biocompatibility is presented. This microfluidic platform will allow for the first kinetic studies of biological reactions with millisecond time resolution under conditions of macromolecular crowding similar to those within cells.
authors.affiliation: Biophysics Program, Department of Mechanical Engineering, University of California, Berkeley, 94720, USA.
authors.forename: Albert
authors.initials: A
authors.lastname: Liau
authors.forename: Rohit
authors.initials: R
authors.lastname: Karnik
authors.forename: Arun
authors.initials: A
authors.lastname: Majumdar
authors.forename: Jamie H Doudna
authors.initials: JH
authors.lastname: Cate
mesh_terms: D001672:Biocompatible Materials; D007477:Ions / Q000737:chemistry; D007700:Kinetics; D044085:Microfluidics / Q000379:methods*; D012996:Solutions / Q000737:chemistry*; D013997:Time Factors
chemical_list: D001672:Biocompatible Materials; D007477:Ions; D012996:Solutions