Microparticles and Microcapsules from the Solvent Extraction of Deep Eutectic Solvent-Based Emulsion

The microparticles of poly(lactic- co -glycolic acid) (PLGA) and poly(methyl methacrylate) (PMMA) and microcapsules of ibuprofen-PLGA, ibuprofen-polylactic acid, and ibuprofen-PMMA were successfully prepared using the solvent extraction of oil-in-deep eutectic solvent (O/DES) emulsions with dichloromethane or ethyl acetate as the solvent of the oil phase, [ChCl] [ dl -malic acid] or [ChCl] [malonic acid] as the DES, and water, 1 wt % poly(vinyl alcohol) solution in water, or ethanol as the antisolvent. The morphologies of the product microparticles and microcapsules were characterized by scanning electron microscopy and found to be dependent on the solvent of the oil phase in the O/DES emulsions rather than the other surfactants, which was essentially the outcome of interplay between polymer solution phase separation and polymer chain mobility. The encapsulation efficiencies and drug loading efficiencies of the microcapsules were determined experimentally in the ranges of 14.5–16.4% and 87.1–98.9%, respectively. The in vitro test confirmed the slow release characteristics of the product microcapsules. Additionally, the information on the miscibility of various organic solvents with DES was collected and presented as fundamental information for the formation of O/DES emulsions. The stability of O/DES emulsions was also monitored by measuring the variations of viscosity and electrical conductivity with time of the emulsion, and the results showed that the stability could be as long as 72 h. Compared to the traditional methods such as solvent evaporation of O/W emulsion and solvent extraction of O/O emulsion, the application of solvent extraction of O/DES emulsion could provide a surfactant-free route and reduce the use of harmful organic solvents, respectively.