Fabrication Of PLGA/PCL Composite Particles With Tunable Structures And Fundamantal Research Of Them In Vitro Degradation

In recent years, the microspheres endowed with special structures and functions have engendered tremendous interest due to their unique properties and potential applications in many fields. Based on phase separation, we successfully fabricated anisotropic particles and microcapsules with special structures using a microfluidic flow-focusing device. What’s more, the morphology and fine structure of them can be tuned by controlling relative factors.At first, we prepared microfluidic flow-focusing devices using standard soft lithography techniques. In order to generate O/W emulsions, a simple but effective PDMS surface modification method is developed. The result of contact angle demonstrates the surface of PDMS is superhydrophilic afer modified with poly(vinyl alcohol)/glycerol(PVA/Gly) solution. Moreover, after one month, the surface of PVA/Gly modified PDMS is still superhydrophilic, which satisfies the demand of our experiment.When the microfluidic chip is finished, we successfully prepare PLGA/PCL composite particles with two distinct architectures from oil-in-water(O/W) single emulsions in the simple microfluidic device via the same protocol for the first time. One of them is PLGA/PCL Janus particle, which possesses two well-defined regions of different surfaces or bulk compositions, but the other one is PLGA/PCL microcapsule which is of typical core-shell configuration. 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. Herein we show that this requirement can be satisfied simply by subtle choice of organic solvents for the dispersed phase. What’s more, the method can produce monodisperse particles with narrow size distribution and control the particle size, shape and structure in a multiple yet accurate manner. ATR-FTIR spectra and acetone treatment demonstrate that PLGA and PCL occupy their own hemisphere in Janus particles. In contrast, the shell on microcapsule particle surface is composed of only PLGA, and the core is composed of PCL in which tiny PLGA beads are embedded. At the same time, the fluorescence images and in vitro degradation test show that Janus and microcapsule particles have promising applications for controllable and programmable drug release.