Hierarchically porous composite microparticles from microfluidics for controllable drug delivery.

Abdominal wall defect repair remains a major clinical need, and a particle-based controllable drug delivery system offers a solution to this problem. Here, we present a new type of hierarchically porous microparticles (HPMs) composed of poly(lactic-co-glycolic acid) (PLGA) and hollow mesoporous silica nanoparticles (HMSNs) for the delivery. The HPMs are generated by drying microfluidic emulsion templates of HMSNs-dispersed PLGA solution. The resultant HPMs have tailorable porous structures, that provide a three-hierarchy architecture for the controlled release of actives. The first hierarchy is formed for controlling the drug release via physical absorption as a result of the presence of the HMSNs in the HPMs. The second hierarchy channels with small pores scattered throughout the surface of the HPMs are formed during evaporation of the solvent. The third hierarchy with openings on the surface of the HPMs is formed as a result of the inner droplets leaking out of the double emulsion templates during the PLGA solidification. Thus, by manipulating the flow of solutions during the microfluidic emulsification, the porous structures of HPMs can be easily and precisely adjusted, and the loaded drugs are delivered at the required rate. These features of the HPMs make them ideal for repairing abdominal wall defects.