PGSS (Particles from Gas Saturated Solutions) is technique for the production of microparticles of different materials of relatively low melting temperatures, such as polymers, waxes or fats. The process is based on the capacity of those materials to dissolve large amounts of CO2 at moderate pressures. Upon depressurization down to ambient conditions, the dissolved CO2 is rapidly released and expanded, producing an intense cooling effect that promotes the formation of microparticles.
The PGSS-drying technique extends the applicability of the PGSS process to aqueous solutions of these active compounds. The PGSS-drying enables a successful drying and micronization of aqueous solutions at operation temperatures significantly below the minimum temperatures required by conventional spray-drying, making it a specially suitable technique for the processing of thermally-sensitive materials, or for materials with very low melting temperatures that would be liquid at the typical operating conditions of spray-drying.
We have a multipurpose plant for batch PGSS process, equipped with a syringe pump that enables operation at pseudo-stationary pressure conditions, and for semicontinuous PGSS-drying process. Some of the applications that we have studied include the production of liposome-forming lecithin formulations, or the encapsulation of vaccines.
Recent updates of our progress with PGSS and PGSS-drying can be found in posts of Marta Salgado.