Solvent elimination from polymer nanoparticle suspensions by continuous supercritical extraction

Nanoprecipitation is a simple and effective process for the production of nanoparticle suspensions. However, until now only a marginal attention has been given to the problem of the solvents elimination from the prepared suspensions; this part of the process is very important in pharmaceutical/medical applications.In this work, a new approach to the problem of acetone and acetone/ethanol mixtures removal, from the suspension of nanoparticles has been proposed, using supercritical CO2 continuous solvent elimination technique. The process parameters: pressure, temperature and liquid to gas ratios have been optimized and it has been tested on two polymers: polylactic-co-glycolic acid (PLGA) and polycaprolactone (PCL). The supercritical assisted post processing allowed to eliminate almost all the solvent residues until few ppm. The suspensions produced were stable and no modifications in the nanoparticles suspension were induced.

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► A new supercritical process operating in continuous is applied for the purification of nanosuspension.
► Polycaprolactone (PCL) and poly-lactic-co-glycolic acid (PLGA) non coalescing nanoparticle suspensions were obtained.
► Supercritical extraction process parameters were optimized and very low solvent residues were obtained.