Usefulness of flow focusing technology for producing subsieve-size cell enclosing capsules: Application for agarose capsules production

Flow focusing technology is known to be advantageous for micro- and nanoparticle production. We investigated the applicability of this technology to produce subsieve-size mammalian cell-enclosing capsules of less than 100 μm in diameter. Subsieve-size capsules with a narrow size distribution were obtained via droplets breakup in a water-immiscible co-flowing liquid flow by a flow focusing process. Compared with the production process of non-flow focusing, the capsules could be prepared with less consumption of the water-immiscible fluid of liquid paraffin. No harmful effects resulting from the flow focusing process on the cells enclosed in the capsules were detected in this study. The undamaged percentage of the cells immediately after the enclosing process was 96.6 ± 1.8%, and the cells enclosed in subsieve-size agarose capsules showed mitochondrial activity for over 3 weeks. These results showed that flow focusing is an effective process for producing cell-enclosing subsieve-size capsules.