Quaternized chitosan/alginate/CaCO3 composite microcapsules were prepared by the coacervation effect of quaternized chitosan and alginate

and in situ precipitation of CaCO3 particles.The composite microcapsules were formed in a microfluidic device based on gas-liquid shearing interaction.The effects of gas flow rate

liquid flow rate

the composition of liquid phase on the size and size distribution of the microcapsules were studied in detail.The morphology and average particle size were characterized and analyzed by 3D video microscopy and SEM.Swelling behavior of the composite microcapsules was studied in aqueous solutions with different pH values and ionic strengths.The encapsulation and release of the microcapsules for model drug were evaluated by ultraviolet spectrophotometry.The optimal conditions to preparing uniform composite microcapsules were the gas rate at 0.7 L/min

the liquid phase rate at 3 mL/h

the alginate concentration at 1.75 wt%

the quaternized chitosan concentration at 0.8 wt%

the Na2CO3 concentration at 0.8 wt% and the CaCl2 concentration at 1.75 wt%.The composite microcapsules swelled in alkaline solutions

but scarcely swelled in acidic solutions and natural water.The microcapsules presented a more efficient drug release rate in alkaline solutions and at 37 ℃.When the alginate amount during preparation of the composite microcapsules increased

the relaese rate of the microcapsules for drug decreased.