Biopolymer-based microparticles for encapsulation of all-trans-retinoic acid

This work aims to investigate the potential of complex coacervation technique to encapsulate and protect all-trans retinoic acid (RA). Gelatin and kappa-carrageenan were used as wall material and pequi oil was employed as a hydrophobic phase. Three formulations with different protein: polysaccharide ratio and pH were defined to produce the microparticles based on the zeta potential and turbidity analysis: (F1) ratio 3:1 and pH 3.5, (F2) ratio 8:1 and pH 3.5, and (F3) ratio 8:1 and pH 5.0. Microparticles were evaluated regarding their morphology, yield, encapsulation efficiency (EE), and stability. The properties of microparticles were mainly affected by the protein: polysaccharide ratio and the turbidity of the mixtures, which is directly related to the protein-polysaccharide interaction. Formulation 1 showed the optimal values of yield (75.6%), EE (100.2%), and stability (85% of the encapsulated RA remained in the particle). The results demonstrated the high potential of this innovative technique to encapsulate RA for a future application in topical formulations.