Characterization of drug delivery particles, produced by supercritical carbon dioxide technologies

This review focuses on characterization methods for drug/excipient particles produced with supercritical CO2 (scCO(2)) particle engineering technologies. Proper characterization of particles can guide optimization of their production process and provide an indication of their in vivo behavior. In particular, characterization techniques for particle size distribution and morphology, drug loading and release, structure of matrix components, potency, porosity, particle surface chemistry, surface charge, biocompatibility and residual solvents are discussed. Moreover, we discuss particle analytical techniques that are not commonly used in the scCO(2) research field but are of potential use for pharmaceutically relevant scCO(2)-engineered particles. These techniques often work synergistically in particle characterization by mutually supporting the interpretation of their outcomes, which is crucial to efficiently develop a successful production process of drug/excipient particles.