title: Stable Ultrathin-Shell Double Emulsions for Controlled Release.
abstract: Double emulsions are normally considered as metastable systems and this limit in stability restricts their applications. To enhance their stability, the outer shell can be converted into a mechanically strong layer, for example, a polymeric layer, thus allowing improved performance. This conversion can be problematic for food and drug applications, as a toxic solvent is needed to dissolve the polymer in the middle phase and a high temperature is required to remove the solvent. This process can also be highly complex, for example, involving UV initiation of polymeric monomer crosslinking. In this study, we report the formation of biocompatible, water-in-oil-in-water (W/O/W) double emulsions with an ultrathin layer of fish oil. We demonstrate their application for the encapsulation and controlled release of small hydrophilic molecules. Without a trigger, the double emulsions remained stable for months, and the release of small molecules was extremely slow. In contrast, rapid release was achieved by osmolarity shock, leading to complete release within 2 h. This work demonstrates the significant potential of double emulsions, and provides new insights into their stability and practical applications.
authors.affiliation: Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia, QLD, 4072, Australia.|School of Engineering and Applied Sciences and Department of Physics, Harvard University, Cambridge, Massachusetts, 02138, USA.
authors.forename: Chun-Xia
authors.initials: CX
authors.lastname: Zhao
authors.affiliation: School of Engineering and Applied Sciences and Department of Physics, Harvard University, Cambridge, Massachusetts, 02138, USA.
authors.forename: Dong
authors.initials: D
authors.lastname: Chen
authors.affiliation: Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia, QLD, 4072, Australia.
authors.forename: Yue
authors.initials: Y
authors.lastname: Hui
authors.affiliation: School of Engineering and Applied Sciences and Department of Physics, Harvard University, Cambridge, Massachusetts, 02138, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Weitz
authors.affiliation: Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia, QLD, 4072, Australia. z.chunxia@uq.edu.au.
authors.forename: Anton P J
authors.initials: AP
authors.lastname: Middelberg
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D004655:Emulsions / Q000737:chemistry; D005395:Fish Oils / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D010316:Particle Size; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D004655:Emulsions; D005395:Fish Oils; D014867:Water
keywords: double emulsions; encapsulation; interfaces; microreactors; surface chemistry