Boron-doped Biphasic Hydroxyapatite/β-Tricalcium Phosphate for Bone Tissue Engineering

Boron-doped hydroxyapatite/tricalcium phosphates (BHTs) were synthesized to study boron uptake and correlate structural alterations of incremental boron addition (0 to 10 mol%). BHTs with a Ca/P ratio of 1.6 were prepared by a wet precipitation/microwave reflux method, sieved (< 70 μm) and characterized. XRD and FTIR analyses revealed that boron slightly distorted apatite crystal, increased crystallinity (95.78 ± 2.08% for 5BHT) and crystallite size (103.39 ± 23.47 nm for 5BHT) and still, boron addition did not show any further detrimental effects. Total surface area (4.05 ± 0.82 m²/g for 10BHT) and mesoporosity (23.90 ± 7.92 μL/g for 10BHT) were expanded as boron content was increased. Moreover, boron addition made grains become smaller (0.21 ± 0.06 μm for 5BHT) and ordered while hardness (10.51 ± 0.86 GPa for 10BHT) increased. Boron incorporation enhanced bioactivity with significantly highest calcium phosphate deposition and protein adsorption (135.29 ± 29.58 μg on 10BHT). In return, boron favored highest alkaline phosphatase activity (4.80 ± 0.40 M_ALP/ng_DNA.min), intracellular calcium (23.61 ± 0.68 g/g_DNA), phosphate (31.84 ± 4.68 g/g_DNA), and protein (23.70 ± 3.46 g/g_DNA) storage in 5BHT without cytotoxicity (128 ± 18% viability compared to pure HT). Compared to literature, it can be pointed out that we successfully employed an optimal procedure for production of BHTs and incorporated significantly higher boron content in HT (5.23 mol%). Additionally, results tended to conclude that 5BHT samples (5 mol% boron in HT) demonstrated a very high potential to be used in composite bone tissue constructs.