title: Selective encapsulation of single cells and subcellular organelles into picoliter- and femtoliter-volume droplets.
abstract: This paper describes a method, which combines optical trapping and microfluidic-based droplet generation, for selectively and controllably encapsulating a single target cell or subcellular structure, such as a mitochondrion, into a picoliter- or femtoliter-volume aqueous droplet that is surrounded by an immiscible phase. Once the selected cell or organelle is encased within the droplet, it is stably confined in the droplet and cannot be removed. We demonstrate in droplet the rapid laser photolysis of the single cell, which essentially "freezes" the state that the cell was in at the moment of photolysis and confines the lysate within the small volume of the droplet. Using fluorescein di-beta-d-galactopyranoside, which is a fluorogenic substrate for the intracellular enzyme beta-galactosidase, we also assayed the activity of this enzyme from a single cell following the laser-induced lysis of the cell. This ability to entrap individual selected cells or subcellular organelles should open new possibilities for carrying out single-cell studies and single-organelle measurements.
authors.affiliation: Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, USA.
authors.forename: Mingyan
authors.initials: M
authors.lastname: He
authors.forename: J Scott
authors.initials: JS
authors.lastname: Edgar
authors.forename: Gavin D M
authors.initials: GD
authors.lastname: Jeffries
authors.forename: Robert M
authors.initials: RM
authors.lastname: Lorenz
authors.forename: J Patrick
authors.initials: JP
authors.lastname: Shelby
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Chiu
mesh_terms: D000818:Animals; D008407:Mast Cells / Q000201:enzymology; D051379:Mice; D044085:Microfluidics / Q000379:methods*; D008928:Mitochondria / Q000201:enzymology; D010782:Photolysis; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D001616:beta-Galactosidase