Facile microfluidic production of composite polymer core-shell microcapsules and crescent-shaped microparticles

Area of Science:

• Biomaterials Science
• Microfluidics
• Cell Biology

Background:

• Core-shell microcapsules and crescent-shaped microparticles offer potential as picolitre bioreactors and cell-trapping microwells.
• Polylactic acid (PLA) is a biocompatible and biodegradable polymer suitable for microencapsulation.

Purpose of the Study:

• To fabricate monodisperse polylactic acid (PLA) core-shell microcapsules.
• To encapsulate Saccharomyces cerevisiae yeast cells within the microcapsules.
• To investigate the morphological stability and transformation of microcapsules under varying osmotic and pH conditions.

Main Methods:

• Microfluidic generation of water-in-oil-in-water (W/O/W) emulsions for core-shell structure formation.
• Solvent evaporation technique for fabricating PLA microcapsules.
• Incubation of microcapsules under different osmotic pressures and pH gradients to observe morphological changes.

Main Results:

• Monodisperse PLA core-shell microcapsules (diameter >200μm, shell thickness 10μm) with 96% water entrapment efficiency were successfully produced.
• Microcapsules maintained shell integrity under isotonic conditions but degraded in hypertonic solutions.
• Incubation in acidic conditions (10⁻⁴M HCl) induced ionic gelation and phase separation of Eudragit S 100 in the core, leading to the formation of crescent-shaped composite microparticles upon drying.

Conclusions:

• PLA core-shell microcapsules can be effectively fabricated using microfluidics and solvent evaporation for encapsulating yeast cells.
• Microcapsule morphology is sensitive to osmotic pressure and pH, enabling controlled degradation and transformation.
• The study demonstrates a method for creating crescent-shaped composite microparticles with potential applications in cell immobilization and drug delivery.