title: Rapid one-step purification of single-cells encapsulated in alginate microcapsules from oil to aqueous phase using a hydrophobic filter paper: implications for single-cell experiments.
abstract: By virtue of the biocompatibility and physical properties of hydrogel, picoliter-sized hydrogel microcapsules have been considered to be a biometric signature containing several features similar to that of encapsulated single cells, including phenotype, viability, and intracellular content. To maximize the experimental potential of encapsulating cells in hydrogel microcapsules, a method that enables efficient hydrogel microcapsule purification from oil is necessary. Current methods based on centrifugation for the conventional stepwise rinsing of oil, are slow and laborious and decrease the monodispersity and yield of the recovered hydrogel microcapsules. To remedy these shortcomings we have developed a simple one-step method to purify alginate microcapsules, containing a single live cell, from oil to aqueous phase. This method employs oil impregnation using a commercially available hydrophobic filter paper without multistep centrifugal purification and complicated microchannel networks. The oil-suspended alginate microcapsules encapsulating single cells from mammalian cancer cell lines (MCF-7, HepG2, and U937) and microorganisms (Chlorella vulgaris) were successfully exchanged to cell culture media by quick (~10 min) depletion of the surrounding oil phase without coalescence of neighboring microcapsules. Cell proliferation and high integrity of the microcapsules were also demonstrated by long-term incubation of microcapsules containing a single live cell. We expect that this method for the simple and rapid purification of encapsulated single-cell microcapsules will attain widespread adoption, assisting cell biologists and clinicians in the development of single-cell experiments.
authors.affiliation: Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Republic of Korea.
authors.forename: Do-Hyun
authors.initials: DH
authors.lastname: Lee
authors.forename: Miran
authors.initials: M
authors.lastname: Jang
authors.forename: Je-Kyun
authors.initials: JK
authors.lastname: Park
mesh_terms: D000464:Alginates / Q000737:chemistry*; D002122:Calcium Chloride; D002214:Capsules / Q000737:chemistry / Q000302:isolation & purification*; D002469:Cell Separation / Q000295:instrumentation / Q000379:methods*; D048430:Cell Shape / Q000502:physiology; D048408:Chlorella vulgaris / Q000166:cytology / Q000302:isolation & purification; D004867:Equipment Design; D020723:Glucuronic Acid / Q000737:chemistry; D056945:Hep G2 Cells; D006603:Hexuronic Acids / Q000737:chemistry; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D061986:MCF-7 Cells; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D019301:Oleic Acid; D010209:Paper
chemical_list: D000464:Alginates; D002214:Capsules; D006603:Hexuronic Acids; D019301:Oleic Acid; D020723:Glucuronic Acid; D002122:Calcium Chloride
keywords: Droplet-based microfluidics; Hydrogel microcapsule; Microcapsule purification; Single-cell encapsulation