Synthesis of nanorod apatites with templates at critical micelle concentrations and in vitro evaluation of cytotoxicity and antimicrobial activity

This study aimed to investigate the synthesis, cytotoxicity, and antimicrobial activity of nanorod apatites obtained using different surfactants at their critical micelle concentrations via hydrothermal method. Nanoscale apatite was obtained from ionic solutions without a template (nHA) compared with synthesized nanorod apatites of T-nHA, S-nHA, F-nHA and P-nHA with four different templates, i.e. the cationic/cetyltrimethylammonium bromide (CTAB), anionic/sodium dodecyl sulfate (SDS), nonionic/Pluronic F-127, and zwitterionic/cocamidopropyl betaine (CAPB) surfactants. Results showed that all of the synthesized apatites have a nanoscale rod-shaped morphology with bacteriostatic properties on day 1. However, only the nanorod apatite of T-nHA demonstrated long-term antibacterial activity up to day 14 due to the combined nanoscale-sized effects and surface phenomena. Among the nanorod apatites produced by the surfactant molecular geometry and solution conditions, the synthesized nanorod apatite of P-nHA possessed the smallest homogeneous crystals. Cytotoxicity results revealed that the nanorod apatites of nHA and F-nHA present insignificant cytotoxicity. Given its acceptable bacteriostatic effect and biocompatibility, the F-nHA may be considered better than nHA. Compared with the conventional-sized apatites, surfactant template-assisted nanorod apatite of T-nHA with high antimicrobial activity may be used as composite grafts for reconstructive surgery to improve inflammation that may be caused by bacteria.