Surfactant-free fabrication of curcumin-loaded emulsion coatings on titanium for biomedical applications

Abstract

Biofunctional emulsion coatings of curcumin-loaded poly(ɛ-caprolactone)/polyvinyl alcohol-hydroxyapatite (Cur-loaded PCL/PVA-HA) were developed on the titanium (Ti) plates without using any surfactant. Firstly, stable oil-in-water emulsions with different water/oil (W/O) ratios (9:1, 7:1, 5:1 and 3:1) were prepared by using the uniform PVA-HA slurry as a water phase and the Cur-loaded PCL solution as an oil phase. The diameter of the oil droplets in those emulsions mostly ranged from 4 to 6 µm. Subsequently, the emulsions were formulated into coatings on Ti through a spin-coating process. The obtained emulsion coatings consisted of Cur-loaded PCL microspheres that were evenly embedded in the PVA-HA matrix, and their phase composition was identified by the FT-IR analysis. The emulsion coatings were hydrophilic and displayed a gradual increase in water contact angles with the decrease of the W/O ratio. Moreover, abundant bone-like apatite aggregates were formed on the emulsion coatings, suggesting their excellent in vitro bioactivity. In addition, the emulsion coatings exhibited a sustained drug release behavior within 2–48 h, and the release process was mainly controlled by diffusion. The present study provides a new perspective on green and facile fabrication of functional emulsion coatings.