Figure 4.

Microcapsule inflation and tracking copolymer accumulation within the microdroplet. A) Rehydration of 1A⁽⁻⁾ ⊂ CB[8] ⊂1B⁽⁻⁾ microcapsules containing dextran cargo (10 × 10⁻⁶m, 70 kDa) confirms that the polymeric skin is retained. B) Real-time laser-scanning confocal fluorescent images of microdroplets containing an aqueous solution of fluorescein-labeled, negatively charged copolymer 1A⁽⁻⁾, [azo] = 60 × 10⁻⁶ m. In the presence of K⁽⁺⁾ (1.0 wt%) diffusion of 1A⁽⁻⁾ to the droplet interface rapidly progresses as it flows along the microfluidic channel, from (1) flow focus to (2) the channel outlet; (3) after leaving the delivery tubing near-quantitative diffusion to the interface had occurred. Dashed lines mark channel boundaries. C) Fluorescence intensity profiles across a transect of a microdroplet as a function of the time-lapsed since generation at the flow-focusing junction, illustrating the kinetics of the rapid diffusion to the droplet interface.