Active curcumin nanoparticles formed from a volatile microemulsion template

We report on the biological performance of organic nanoparticles formed by a simple method based on rapid solvent removal from a volatile microemulsion. The particular focus of the study was on testing the suitability of the method for substances soluble in partially water-miscible organic solvents as well as on evaluating the therapeutic activity of the resultant nanoparticles. Curcumin was employed as a model for hydrophobic drugs, and, as it is soluble in water-miscible organic solvents, it was successfully incorporated into a new cyclopentanone-water microemulsion system. During rapid solvent removal by spray-drying, the nanometric droplets of the microemulsion were converted into nanoparticles containing amorphous curcumin with an average size of 20.2 +/- 3.4 nm, having a zeta potential of -36.2 +/- 1.8 mV. These nanoparticles were dispersible in water and retained the high loading of the active substance. The therapeutic activity of the resulting nanoparticles was demonstrated in a pancreatic cancer cell line, PANC-1. The effective concentration for reducing the metabolic activity by 50% (EC50) was found to be 11.5 mu M for nanoparticles compared with 19.5 mu M for free curcumin.