Spray-drying of oil-in-water emulsions for encapsulation of retinoic acid: Polysaccharide- and protein-based microparticles characterization and controlled release studies

Oil-in-water emulsions were proposed to produce retinoic acid (RA)-loaded biopolymer-based delivery systems applying spray-drying technology. They were characterized regarding rheological properties (i.e. viscosity), stability and droplet size distribution. The usage of a spray-dryer inlet air temperature of 130 ֯C significantly increased RA encapsulation efficiency for modified chitosan-based microparticles. Empty and oil-loaded (with and without RA) microparticles were produced with a product yield between 12 and 41%. Microparticles with a mean diameter from 1.712 ± 0.004 and 12.9 ± 0.3 μm were produced, as well as with a morphology that varied from a very smooth to a high rough surface structure. The time required for the complete RA release from microparticles to the surrounding environment (octanol) – release time – varied according to the biopolymers used in the microparticles formulations. The faster RA controlled release was registered from microparticles composed by xanthan and arabic gums (48 and 94 min, respectively). In turn, alginic acid sodium-based microparticles enabled to increase the RA release time for almost 8 h.