Microfluidic preparation of PLGA composite microspheres with mesoporous silica nanoparticles for finely manipulated drug release

• Microfluidic-preparation of PLGA composite microspheres with mesoporous silica nanoparticles. • PLGA-MSNs with sustainable long-term drug release without burst release. • Internal structural modulation of PLGA microspheres via MSN incorporation. The current study explored the feasibility of a microfluidic preparation of PLGA composite microspheres with mesoporous silica nanoparticles (MSNs) to finely manipulate the drug release behaviors of the microspheres. MSNs were synthesized via a hydrothermal method, and PLGA microspheres loaded with MSNs (PLGA-MSNs) were prepared using a capillary-based three-phase microfluidic device. Drug loading and release behaviors using rhodamine B (RB) as a water-soluble model drug were investigated and compared with those of PLGA microspheres. MSNs with an average particle size of 119 nm, a specific surface area of 902.5 cm 2 /g, and a pore size of approximately 5 nm were obtained. The mean diameter of PLGA-MSNs was 56 μm (CV = 4.91%). A sustained release duration of encapsulated RB from PLGA-MSNs for 4 months was achieved without any observable burst release. PLGA microspheres with monodispersion could also allow for a similar release duration of encapsulated RB but encountered a burst release in the mid-term of the studied duration. PLGA-MSNs had a denser outer PLGA layer and a more centralized hollow hole than PLGA microspheres without MSNs. Hence, the incorporation of MSNs into PLGA microspheres via microfluidics could be an efficient strategy to finely tune the drug release behavior of PLGA microspheres.