Solvent effects on the porosity and size of porous PLGA microspheres using gelatin and PBS as porogens in a microfluidic flow-focusing device

In this study, we analyzed the effects of four solvents—dimethylcarbonate (DMC), ethylacetate (EA), dichloromethane (DCM), and chloroform (CH)—on the porosity and size of porous PLGA microspheres produced using aqueous gelatin and phosphate-buffered saline (PBS) as porogens in a microfluidic flow-focusing (MFF) device. Relatively water soluble solvent such as DMC and EA miscible with aqueous porogen solution/porogen, did not produce porous microspheres, while poor water soluble solvents such as DCM and CH produced highly porous microspheres. Furthermore, as the immiscibility of the polymer solution and porogen increased, the porosity and pore size also increased. Similarly, the highly volatile solvents (DCM and CH) resulted in smaller microspheres than EA and DMC, which are less volatile. The porosity of porous microspheres also depended on the porogen. Aqueous gelatin produced highly porous microspheres, while PBS resulted in smaller pore sizes.