Effect of Cu2+ ion on Biological Performance of Nanostructured Fluorapatite Doped with Copper

Nanostructured copper-doped fluorapatite (Cux.Ca(10-x).(PO4)6.F2) having crystallite sizes of 19, 29 and 34 nm at x = 0.9, 0.4 and 0.0, respectively, was synthesized by planetary ball milling of CaO, P2O5, CaF2 and CuO powders. Specifications of the products were determined by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. In-vitro studies and Mossman's Tetrazole Test (MTT) assays were also conducted by incubating Cux.Ca(10-x).(PO4)6.F2 powder into Kokubo’s simulated body fluid (SBF) and against BT-20 cell, respectively, to determine bioactivity and biocompatibility of the material. Antibacterial effects toward Staphylococcus aureus was assessed by the disc diffusion test method. Measurements showed that the rate of formation of fluorapatite was lowered by Cu content. Besides, in vitro experiments showed the same SBF interacted apatite precipitation for all samples. In contrast, MTT assays revealed different behavior for pure fluorapatite and apatite with x=0.9 Cu against BT-20 cell after 24 h of incubation. This highlights increase of fluorapatite cytotoxicity when Cu ion is present in the apatite structure. Copper-doped fluorapatite was, however, desirably antibacterial. This stemmed from copper ions interactions with the bacterial metabolism which resulted in enzymes neutralization and copper-doped fluorapatite antibacterial behavior