Fabrication and structural regulation of PLLA porous microspheres via phase inversion emulsion and thermally induced phase separation techniques

Abstract

In this work, a facile, scalable technique was developed to produce biodegradable porous microspheres by combining an oil‐in‐oil (O/O) surfactant‐free phase inversion emulsion technique with thermally induced phase separation (TIPS) method. The effects of PLLA concentration, stirring speed, macromolecule weight, and organic solvents on the size and microstructure of microspheres were investigated by scanning electron microscopy (SEM). The results revealed a highly porous structured microsphere with controllable sizes and morphologies by tuning the synthesis conditions. The typical resulting PLLA microspheres consist of nanoscale topographic structured surface and highly microporous interior. The coarse nanotopography and microcellular inner structure lead to a high drug loading capacity up to 60% for the PLLA microspheres from THF. The cumulative release percentage of the ibuprofen could reach 80% for drug‐loaded microspheres with different microstructures. The fabricated PLLA microspheres would have potential applications in the field of drug delivery and tissue engineering. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44885.

Unique leafy morphology of poly(lactic acid) monoliths controlled via novel phase separation technology

“…Furthermore, this study demonstrates that the addition of mid-solvent may expand selection of controlling factor for pore and skeletal size. For over decades, TIPS with binary good/poor solvent have been widely used, [9][10][11][17][18][19] while this oen limits the condition of fabrication. For example, Tanaka et al reported that PLLA monoliths were produced by TIPS using binary 1,4dioxane/water solvent with the limited ratio around 87/13 w/ w% at 10 wt% of PLLA concentration.…”

“…Among those techniques of producing PLA monoliths, recently, phase separation has been utilized due to its excellent versatility, simplicity, and controllability in pore size compared to other methods. [9][10][11][15][16][17][18][19] Furthermore, good processability is also key factor of this method since the shape of monolith is dependent on the shape of vessels where the phase separation and gelation take place. This method can mainly be classied into two for preparation of monoliths from PLA by types of trigger to occur phase separation: non-solvent induced phase separation (NIPS) and thermally induced phase separation (TIPS).…”

“…By contrast, TIPS method has also been utilized to prepare PLA monolith. [9][10][11][17][18][19] In the TIPS method, the drop in polymer solubility induced by solution temperature leads phase separation. Distinct from NIPS process, TIPS has remarkable advantages in reproducibility and exibility since the phase separation is occurred by simple temperature reduction rather than non-solvent exchange which include variables that need to be controlled.…”

Simple method for preparation of thermally expandable microspheres of PMMA encapsulating NaHCO3via thermally induced phase separation

“…In the polymer solution TIPS process, the polymers are dissolved in the solvent at high temperature, and polymeric particles are generated by the polymer precipitating with cooling . Nie et al . developed biodegradable porous microspheres by the TIPS method.…”

One‐Step Fabrication of Uniform Biodegradable Microbeads with Unimodal and Bimodal Porous Structures Using Spontaneous Microphase Separation

“…In addition, they are used as small building blocks in the construction of large organs in bottom‐up tissue engineering . Many research groups have demonstrated the fabrication of porous microbeads using numerous techniques including gas formation, melt‐molding and particle leaching, freeze‐drying, air incorporation, emulsion templating, and thermally induced phase separation . Most of the studies, however, are hampered by disadvantages in terms of the pore size control and the multistep fabrication procedure.…”