TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The particle has a diameter of 10 nm to 50 mu m. The organic salt: has a melting point below 200 degrees C, preferably below 100 degrees C; and comprises an organic cation/anion. The organic salt comprises: an organic anion with antimicrobial/antiviral activity, and/or an organic cation with antimicrobial/antiviral activity; or an organic anion with magnetic/fluorescent properties, and/or an organic cation with magnetic/fluorescent properties. The emulsion: comprises micelles or reverse micelles containing the organic salt; and additionally comprises a surfactant. The first fluid comprises an aerosol comprising a gas and a solution of the organic salt. Preferred Method: In the method, the step (a) comprises forming an emulsion from a liquid and a salt, at a temperature above the melting point of the salt, and the step (b) comprises cooling the emulsion to a temperature below the melting point of the salt, where the salt is substantially insoluble in the liquid at the temperature of the emulsion, and the rate of the cooling is sufficiently rapid to cause the formation of solid particles. The first fluid comprises a solution of the organic salt in a liquid, in which the organic salt is soluble, where the dispersing step comprises forcing the first fluid through many nozzles into the second fluid, and the second fluid comprises a liquid in which the organic salt is insoluble. EXAMPLE - Solid 1-butyl-2,3-dimethylimidazolium hexafluorophosphate (25 mg) was gently rinsed several times in ultrapure water (18.2 M Omega cm), and then was added to ultrapure water (8 ml) in a 20 ml scintillation vial. The sealed vial was heated to 70 degrees C in a water bath until the 1-butyl-2,3-dimethylimidazolium hexafluorophosphate melted to form a clear, dense liquid phase. The mixture was then homogenized using a commercial homogenizer at 30000 rpm for 10 minutes, while the sample was maintained at 70 degrees C in the water bath. The mixture was then sonicated with a probe ultrasound processor at 35% intensity (i.e. 35% of a maximum 300W power output) for 10 minutes. The sonication frequency and power affected the size of the particles, although not strongly. Lower frequency sonication produced more uniform particles, and higher power produced smaller particles. Following sonication, the mixture was immediately placed into an ice-water bath to rapidly reduce the temperature below the melting point of the 1-butyl-2,3-dimethylimidazolium hexafluorophosphate. The resulting nanoparticles, suspended in the aqueous phase, were washed by ultrafiltration (millipore) three times to remove soluble species.