Chitosan Microparticles Production by Supercritical Fluid Processing

In this work chitosan (CS) in 1% acetic acid aqueous solutions has been successfully micronized using supercritical assisted atomization (SAA), which is a new and very promising supercritical fluid process. Some process parameters such as precipitation temperature and solute concentration in the liquid solution have been explored to evaluate their influence on the morphology and size of precipitated particles. Noncoalescing spherical microparticles have been produced as confirmed by scanning electron microscopy analysis. Laser scattering particle size analysis has shown that these precipitates have a sharp distribution: 99% of particles produced show diameters ranging between 0.1 and 1.5 (mu)m, when precipitated from solutions with chitosan concentrations ranging between 1 and 10 mg/mL. X-ray and differential scanning calorimetry analyses have also been used to investigate CS modifications induced by SAA processing. A decrease in crystallinity has been observed when higher precipitation temperatures have been used. SAA micronized CS microparticles are expected to be promising vehicles for drug delivery.