title: Microfluidic production of biopolymer microcapsules with controlled morphology.
abstract: We report a microfluidic approach to generating capsules of biopolymer hydrogels. Droplets of an aqueous solution of a biopolymer were emulsified in an organic phase comprising a cross-linking agent. Polymer gelation was achieved in situ (on a microfluidic chip) by diffusion-controlled ionic cross-linking of the biopolymer, following the transfer of the cross-linking agent from the continuous phase to the droplets. Gelation was quenched by collecting particles in a large pool of cross-linking agent-free liquid. The structure of microgels (from capsules to gradient microgels to particles with a uniform structure) was controlled by varying the time of residence of droplets on the microfluidic chip and the concentration of the cross-linking agent in the continuous phase. We demonstrated the encapsulation of a controlled number of polystyrene beads in the microgel capsules. The described approach was applied to the preparation of capsules of several polysaccharides such as alginate, kappa-carrageenan, and carboxymethylcellulose.
authors.affiliation: Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario M5S 3H6, Canada.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Ethan
authors.initials: E
authors.lastname: Tumarkin
authors.forename: Raheem
authors.initials: R
authors.lastname: Peerani
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Nie
authors.forename: Ruby May A
authors.initials: RM
authors.lastname: Sullan
authors.forename: Gilbert C
authors.initials: GC
authors.lastname: Walker
authors.forename: Eugenia
authors.initials: E
authors.lastname: Kumacheva
mesh_terms: D002214:Capsules; D020100:Hydrogels / Q000138:chemical synthesis / Q000737:chemistry*; D044085:Microfluidics / Q000379:methods*; D018625:Microscopy, Atomic Force; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D011134:Polysaccharides / Q000138:chemical synthesis / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry*
chemical_list: D002214:Capsules; D020100:Hydrogels; D011134:Polysaccharides; D011137:Polystyrenes