Particle generation

Particle processes using supercritical carbon dioxide (CO2)

Various processes with supercritical CO2 have been developed which allow the generation or modification of fine particles with defined particle size distributions in micro- and even nano-scale of certain shape and/or determined morphology. This technology is of great relevance to produce pharmaceutical products and substances, because the release kinetics of active pharmaceutical ingredients (APIs) are significantly influenced by the particle properties. New drugs with more exact and controlled properties are possible by using these processes, complementing traditional granulation and spray drying processes.

Schematic depiction of the GAS-Process (Gas Antisolvent Crystallization)

Characteristics of high-pressure micronisation

  • Physical characteristics when applying supercritical fluids to melts/solutions:

    • reduction of viscosity

    • reduction of surface tension.

  • Quick super-saturation by pressure change and contact to supercritical fluid, respectively

  • High nucleation rate, small growth rate

  • Particles in micro- or nano-scale possible


Schematic depiction of the RESS-Process (Rapid Expansion of Supercritical Solutions)

Advantages of using supercritical fluids

  • Particle size: micro- to nanometer

  • Narrow particle size distribution

  • Control of particle geometry (spherical, needle, etc.)

  • Morphology (smooth, porous, massive) controllable

  • Applicable to difficult substances, for example with high melting points or high viscosity

  • Low thermal stress due to mild temperature conditions

  • No oxidation due to inert atmosphere

  • Possibility of generation of composites

Schematic depiction of the PGSS™-Process (Particles from Saturated Solutions)