Effects of different cryoprotectants on morphology of lyophilized poly(ε-caprolactone) micro and nanospheres

A common limitation of using polymeric micro and nanoparticles in long-term conservation is due to their poor physical and chemical stability. Freeze-drying is one of the most convenient methods that enable further reconstitution of micro and nanoparticles for therapeutical use. Nevertheless, this process generates various stresses during freezing and desiccation steps. The aim of this study was to evaluate different cryoprotectants (protective excipients that are usually added to increase stability upon storage and protect the particles from freezing stress): sugars (glucose and sucrose) and polymers (PVA and PGA), on the outcome of freeze-dried poly(ε-caprolactone) micro and nanospheres. The best freeze-drying results in terms of morphological characteristics, analyzed with SEM, were achieved with glucose at concentration of 1%. The FTIR analysis confirmed that the molecular structure of PCL particles remained the same after the addition cryoprotectants