Fabrication of monodisperse liposomes-in-microgel hybrid microparticles in capillary-based microfluidic devices

•A drop-based microfluidic approach is introduced to physically immobilize liposomes in uniform microgel particles.•Liposomes-in-microgel particles have the bigger apparent mesh size than bare microgel particles.•Liposomes-in-microgel particles can not only remarkably retard drug releasing, but also show a sustained release behavior.

This study introduces a drop-based microfluidic approach to physically immobilize liposomes in microgel (liposomes-in-microgel) particles. For this, we generate a uniform liposomes-in-water-in-oil emulsion in a capillary-based microfluidic device. Basically, we have investigated how the flow rate and flow composition affect generation of emulsion precursor drops in micro-channels. Then, the precursor emulsion drops are solidified by photo-polymerization. From characterization of hydrogel mesh sizes, we have figured out that the mesh size of the liposomes-in-microgel particles is bigger than that of bare microgel particles, since liposomes take space in the hydrogel phase. In our further study on drug releasing, we have observed that immobilization of liposomes in the microgel particles can not only remarkably retard drug releasing, but also enables a sustained release, which stems from the enhanced matrix viscosity of the surrounding hydrogel phase.

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