Antibacterial efficacy and cytotoxicity studies of copper (II) and titanium (IV) substituted hydroxyapatite nanoparticles

Cu2+ and Ti4+ substituted hydroxyapatite (CuHA; TiHA) in different molar ratios (Madded/Caadded = 0.01, 0.05, 0.10 and 0.15) were synthesized using wet chemical method coupled with ion exchange reaction. All characterization results confirmed the samples were hydroxyapatite (HA). XRD data showed that all samples were single phased. Both intensity and width of XRD peaks did not change significantly as substitution concentration increased. The FTIR spectra revealed the occurrence of CO32− ions (B-type carbonated HA). ICP data indicated that the content of Cu and Ti in CuHA and TiHA increased with initial metal salt concentration. Visual examination by FESEM showed all samples possessed elongated spheroid morphology with crystal size of around 70 nm. The CuHA nanoparticles possessed high antibacterial property against Escherichia coli. This was probably due to the leaching of Cu2+ ions which subsequently led to the lysis of bacteria. TiHA had slight antibacterial effect compared to pure HA at high Ti content (Tiadded/Caadded = 0.1). Agar diffusion and extraction cytotoxicity assay revealed that the presence of Cu2+ was cytotoxic while Ti4+ was only slightly toxic to osteoblasts.