Issue 88, 2016, Issue in Progress

Methylamine acts as excellent chemical trigger to Harden emulsion droplets into spongy PLGA microspheres

Abstract

The purpose of this research was to produce porous sponge-like PLGA microspheres through a simple emulsion technique using a non-halogenated organic solvent and methylamine. In order to achieve this objective, a dispersed phase consisting of PLGA and methyl propionate was emulsified in an aqueous polyvinyl alcohol solution to produce an oil-in-water emulsion. When methylamine was added to the aqueous phase, it partitioned to the oil phase and reacted with methyl propionate to produce methanol and N-methyl propionamide. These water-soluble decomposition products acted as anti-solvents against PLGA. As they leached to the aqueous phase, oil droplets effectively hardened to sponge-like microspheres. This technique, utilizing a chemical reaction between the dispersed solvent and methylamine, has shown excellence compared to the existing water-in-oil-in-water emulsion techniques that require the help of porogens. For example, even without using porogens and high-shear/high-energy mixing devices, our simple technology made it possible to produce very porous microspheres with a sponge-like skeleton. Also, rather than using halogenated methylene chloride, which has been commonly used to produce microspheres, this new technique used methyl propionate, a non-halogenated and safer alternative. Furthermore, it enabled us to adjust the amount of residual methyl propionate in the microspheres below 0.5%, meeting the standard of residual organic solvents in microspheres set by regulatory authorities. The innovative technology reported in this study would make a large contribution to producing porous microspheres with the use of various hydrophobic polymers.

Graphical abstract: Methylamine acts as excellent chemical trigger to Harden emulsion droplets into spongy PLGA microspheres

Supplementary files

Article information

Article type
Paper
Submitted
09 Jul 2016
Accepted
01 Sep 2016
First published
07 Sep 2016

RSC Adv., 2016,6, 85275-85284

Methylamine acts as excellent chemical trigger to Harden emulsion droplets into spongy PLGA microspheres

Y. Kim, H. Kim and H. Sah, RSC Adv., 2016, 6, 85275 DOI: 10.1039/C6RA17576G

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