Controllable microfluidic fabrication of Janus and microcapsule particles for drug delivery applications

Janus and microcapsule particles are very attractive for drug delivery applications due to their capability of targeted and/or programmed drug release. In this paper, a facile yet robust strategy is reported for the first time to fabricate both Janus and microcapsule particles in a simple microfluidic device via the same protocol. According to the classic spreading and partial wetting theory, the key point to fabricate Janus and microcapsule particles in single emulsions is that the two immiscible components should undergo a precisely controlled phase separation, i.e., dewetting for Janus particles and wetting for microcapsule particles. Herein we show that this requirement can be satisfied simply by a subtle choice of organic solvents for the dispersed phase. As a model hybrid material, PLGA/PCL Janus and microcapsule particles are obtained via switching the organic solvent between dimethyl carbonate and dichloromethane. ATR-FTIR spectra and acetone treatment demonstrate that PLGA and PCL occupy their own hemisphere in the Janus particles. In contrast, the shell on the microcapsule particle surface is composed of only PLGA, and the core is composed of PCL in which tiny PLGA beads are embedded. The applications of PLGA/PCL Janus and microcapsule particles in drug delivery are characterized via an in vitro degradation test. The results prove that Janus and microcapsule particles exhibit distinct degradation behaviors, implying their capability of programmable drug delivery in different manners.