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Investigation of the influence of TiO2 distribution on HA/TiO2 composite wetting ability using the dispersant SDBS, high-temperature annealing, and ultrasonication

The use of composites such as hydroxyapatite (HA)/TiO2 in bioapplications has attracted increasing attention in recent years. Herein, for the enhancement wetting ability and biocompatibility, the HA/TiO2 composite was subjected to different treatments to improve nanoparticle (NP) distribution and surface energy with an aim of mitigating nanotoxicity concerns. The treatments included ultrasonication, high-temperature annealing, and addition of a dispersant and surfactant, sodium dodecylbenzenesulfonate (SDBS). Contact angle measurement tests revealed the effect of SDBS addition on the distribution of TiO2 NPs on the HA surface: a decrease in the contact angle and, thus, an increase in the wetting ability of the HA/TiO2 composite were observed. The combination of annealing and SDBS addition treatments allowed for guest TiO2 particles to be uniformly distributed on the surface of the host HA particles, showing a rapid conversion from a hydrophobic to superhydrophilic property. In vitro investigation suggested that the cell viabilities of annealed HA/TiO2, SDBS-added HA/TiO2, and SDBS-added and annealed HA/TiO2 reached 89.7%, 94.7%, and 95.8%, respectively, while those of HA and untreated HA/TiO2 were 80.3% and 86.9%, respectively. The modified composites exhibited lower cytotoxicities than the unmodified systems (HA and HA/TiO2). Furthermore, the cell adhesion behavior of the composites was confirmed through actin-4′,6-Diamidino-2-phenylindole (DAPI) staining, which showed negligible changes in the cytoskeleton architecture of the cells. This study confirmed that a modified HA/TiO2 composite has potential for bioapplications.