title: Bioreactor droplets from liposome-stabilized all-aqueous emulsions.
abstract: Artificial bioreactors are desirable for in vitro biochemical studies and as protocells. A key challenge is maintaining a favourable internal environment while allowing substrate entry and product departure. We show that semipermeable, size-controlled bioreactors with aqueous, macromolecularly crowded interiors can be assembled by liposome stabilization of an all-aqueous emulsion. Dextran-rich aqueous droplets are dispersed in a continuous polyethylene glycol (PEG)-rich aqueous phase, with coalescence inhibited by adsorbed ~130-nm diameter liposomes. Fluorescence recovery after photobleaching and dynamic light scattering data indicate that the liposomes, which are PEGylated and negatively charged, remain intact at the interface for extended time. Inter-droplet repulsion provides electrostatic stabilization of the emulsion, with droplet coalescence prevented even for submonolayer interfacial coatings. RNA and DNA can enter and exit aqueous droplets by diffusion, with final concentrations dictated by partitioning. The capacity to serve as microscale bioreactors is established by demonstrating a ribozyme cleavage reaction within the liposome-coated droplets.
authors.affiliation: Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Dewey
authors.affiliation: 1] Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, USA [2] Center for RNA Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Strulson
authors.affiliation: Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: David N
authors.initials: DN
authors.lastname: Cacace
authors.affiliation: 1] Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, USA [2] Center for RNA Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Philip C
authors.initials: PC
authors.lastname: Bevilacqua
authors.affiliation: Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Christine D
authors.initials: CD
authors.lastname: Keating
mesh_terms: D019149:Bioreactors; D004247:DNA / Q000737:chemistry*; D003911:Dextrans / Q000737:chemistry*; D004655:Emulsions; D016650:Fluorescein-5-isothiocyanate; D036681:Fluorescence Recovery After Photobleaching; D005456:Fluorescent Dyes; D008081:Liposomes / Q000737:chemistry*; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry*; D016337:RNA, Catalytic / Q000737:chemistry*; D012235:Rhodamines; D055672:Static Electricity; D014867:Water / Q000737:chemistry
chemical_list: D003911:Dextrans; D004655:Emulsions; D005456:Fluorescent Dyes; D008081:Liposomes; D016337:RNA, Catalytic; D012235:Rhodamines; D014867:Water; D011092:Polyethylene Glycols; D004247:DNA; D016650:Fluorescein-5-isothiocyanate