Synthesis, characterisation and antibacterial effects of sol-gel derived biphasic calcium phosphate nanopowders

Hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) represent the main types of calcium phosphates used for the reconstruction of bone defects in maxillofacial, dental, orthopaedic and drug delivery applications. The bioactivity and bioresorbability of biphasic calcium phosphate (BCP) ceramics can be controlled by varying the HA/β-TCP ratio. In this reported work, BCP nanopowders were prepared by a simple sol-gel method, in which Ca(NO₃)₂ · 4H₂O and P₂O₅ were used as precursors for calcium and phosphate, respectively. The different phase ratios of HA/β-TCP were obtained by changing the sintering temperature. X-ray diffraction, inductive coupled plasma-atomic emission spectroscopy, scanning electron microscopy, transmission electron microscopy and Fourier transformer infrared spectrophotometer results have shown that increasing the sintering temperature could cause more decomposition of HA into β-TCP. Moreover, the size of the prepared nanoparticles was measured between 10 and 500 nm. Finally, the antibacterial activity was studied using Escherichia coli (ATCC 25922) as the Gram-negative bacteria. The antibacterial effect of the BCP sample with 50% HA-50%β-TCP phase ratio was tested at concentrations of 100, 200 and 300 mg/ml. The results showed bacterial growth reduction at a concentration of 300 mg/ml, which makes it a good candidate for the treatment of bone defects.