Organic nanoparticles recovery in supercritical antisolvent precipitation

One of the major problems in dry nanoparticles production and handling is their recovery. Indeed, they tend to disperse in all the precipitation chamber and, due to their dimensions, are very difficult to collect.Supercritical antisolvent precipitation (SAS) was frequently used to produce nanoparticles at very mild conditions of pressure and temperature, but the issues of sedimentation mechanisms and nanoparticles recovery as single units, have not been evaluated yet.In this work, SAS nanoparticles were produced for samarium acetate, rifampicin, astemizole, amoxicillin trihydrate, tetracycline hydrochloride, clemastine, cellulose acetate and disperse red 60; the powders were collected as aggregates, due to the specific sedimentation mechanism that characterizes the process. SAS produced nanoparticles of the previously listed materials were precipitated from different organic solvents. Then, they were post-processed by ultrafiltration, ultracentrifugation and ultrasound based techniques, demonstrating that they can be easily separated in single nano-units. Nanoparticles showed mean diameters in the range 50–150 nm.

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