Formation of biodegradable microcapsules utilizing 3D, selectively surface-modified PDMS microfluidic devices.

We have successfully demonstrated the formation of biodegradable microcapsules utilizing PDMS double-emulsification devices. Specially designed 3D PDMS microchannels with surfaces selectively modified by a self-aligned photografting process are employed to generate monodisperse water-in-organic-solvent-in-water (W/O/W) emulsions in a controlled manner. Mainly by varying the outer and inner fluid flow-rates, the dimensions of resulting double emulsions can be adjusted as desired. Meanwhile, biodegradable materials are dissolved in the middle organic solvent (in this work ethyl acetate is used), and solidified into microcapsules once the solvent is extracted. In the prototype demonstration, microcapsules made up of poly(L-lactic acid), trilaurin, and phosphocholine were successfully fabricated. In addition, it was also demonstrated that gamma-Fe(2)O(3) nanoparticles can be simultaneously embedded into the microcapsules, which consequently become responsive to electromagnetic stimulation. As such, the presented PDMS microfluidic devices could potentially serve as versatile encapsulation apparatus, and the fabricated biodegradable microcapsules could function as controlled delivery systems, which are desired for a variety of biological and pharmaceutical applications.