Preparation and Characterization of Titanium Oxide Nanocapsules Containing Retinoic Acid for Sustained Release

Retinoic acid (RA) is widely used in cosmetics and medicine. However, high concentrations of RA may cause adverse effects, and carcinogenic substances can be generated by light degradation. Herein, a convenient and eco-friendly method was developed to achieve the sustained release of RA by TiO 2 nanocapsules. The surface morphologies, crystalline properties, and chemical structures were studied by SEM, XRD, FT-IR, NMR. The particle size is ~ 200 nm. The synthesis conditions, photostability and biological properties were also investigated. The XRD results indicated that the low crystallinity of anatase TiO 2 shell contributed to the sustained release of inner RA. The sustained release properties were investigated by the elution process. It confirmed that the RA was encapsulated in the TiO 2 shell with loose structures. Light irradiation experiments showed that the irradiation time was extended from ~ 30 s to ~ 120 s when the concentration of residual RA was reduced to half under the same conditions. This showed that inner RA was well protected and continuously released. The RA-TiO 2 nanocapsules showed good dispersion in water and oil phases, sustained release properties, extended effect time, long-acting antibacterial properties and photostability.