Nanoparticle Production of Zingiber officinale Roscoe Rhizome Extracts by ESS (Expansion of Supercritical Solution)

A vast number of methods have been applied to water-insoluble pharmaceuticals to improve their solubility. Nanoparticle production of pharmaceuticals is considered as one of the high-speed ways to improve solubility. Objective: Supercritical CO2 was applied to extract Zingiber officinale Roscoe rhizome pharmaceutical. Then, a modified RESS (Rapid Expansion of Supercritical Solution) method, called ESS (Expansion of Supercritical Solution), was exerted to obtain NPs (nanoparticles) of the extracted pharmaceuticals. Methods: Initially, applying high pressure in supercritical CO2 contributed to the extract dissolution such that supercritical CO2 was saturated with the sample. Then, by decreasing the pressure, an expansion occurred in the saturated medium. This expansion reduced the power of supercritical CO2 solvent and induced the sample nanoparticle nucleation in the needle valve. Results: LC-MS (Liquid Chromatography-Mass Spectrometry) and EDX (Energy Dispersive X-ray Spectroscopy) result provided solid evidence for the presence of anti-cancer pharmaceutical, [6]-Gingerol, in the extract. The medium size of the nanoparticles in FESEM (Field Emission Scanning Electron Microscopy) analysis was 36 nm. The most satisfactory parameters for a 2 mg mL^-1 feeding solution were the initial pressure of 350 atm, secondary pressure of 160 atm, equilibrating time of 10 min, precipitating time of 20 min, and temperature of 48 °C. Conclusion: Unlike rapid expansion of supercritical solution methodology, in this technique, the initial and secondary pressures were permanently above the critical pressure to provide a gentle expansion, which contributes to the production of uniform and small particles. The obtained uniform NPs had a narrow size distribution. Consequently, ESS technique can be considered as an efficient technique for improving the solubility of hydrophobic pharmaceuticals, such as [6]-gingerol.