Adsorption and desorption behaviors of cetylpyridinium chloride on hydroxyapatite nanoparticles with different morphologies.

Application of hydroxyapatite (HAp) nanoparticles to repair damaged enamel has attracted recent attention. In this study, HAp nanoparticles with various morphologies (spherical, short-rod, long-rod and fiber morphologies) were synthesized via chemical precipitation methods without the addition of template molecules, and the adsorption/desorption behaviors of a cationic antibacterial agent, cetylpyridinium chloride (CPC), on the HAp nanoparticles were evaluated. The adsorption of CPC on each HAp nanoparticle showed Langmuir-type adsorption, and the short-rod/long-rod HAp nanoparticles showed thermodynamically more stable adsorption of CPC than that with the spherical/fiber HAp nanoparticles. The desorption rate of CPC from the short-rod/long-rod HAp nanoparticles was slower than that of the spherical/fiber HAp nanoparticles. The HAp nanoparticles with different CPC release profiles presented here have potential applications as nanoparticulate enamel repair agents with antibacterial properties.