Nanometric particles of a model hydrophobic substance curcumin were prepared by a novel method, namely, flash nanoprecipitation from a coarse oil-in-water emulsion. The method employs turbulent co-mixing of water with curcumin-loaded emulsion using manually-operated confined impingement jets mixer. A clear and stable dispersion of nanoparticles was formed in this process, and could be converted to dry, easily water-dispersible powder by spray drying. The mean size of the particles was about 40. nm by DLS, confirmed by Cryo-TEM. The obtained particles contained 20.4. wt% curcumin, X-ray analysis showed it was amorphous. The significant advantages of the studied process are its feasibility, speed and low cost. It does not require any special high-energy input equipment to reduce the droplet size of the initial emulsion as required by the vast majority of other methods, and relies on rapid turbulent mixing and on flow-induced shear stress formed in the simple, manually-operated mixer. Control experiments clearly indicate that employing emulsion, instead of a plain solution and flash nanoprecipitation instead of a simple antisolvent precipitation are advantageous in terms of particle size and stability.
Bibliographical noteFunding Information:
We would like to acknowledge partial financial support from the University of Minnesota Futures Grant Program and the National Institute of Health (EB011671). Parts of this work were carried out in the University of Minnesota, member of the NSF-funded Materials Research Facilities Network ( www.mrfn.org ) via the MRSEC program and which receives partial support from NSF through the NNIN program. We would also like to thank Dr. Vladimir Uvarov from the Center for Nanoscience and Nanotechnology, the Hebrew University of Jerusalem, for performing XRD measurements and for helpful discussions.
- Flash nanoprecipitation
- Spray drying