Boron doped Hydroxyapatites in Biomedical Applications

Abstract

Hydroxyapatite has been widely used in biomedical applications as a coating material for implant surfaces, a drug carrier, a scaffold or composite for bone tissue engineering applications. The highly ionic structure of hydroxyapatite allows doping of various ions, resulting in an improvement in its properties. Boron is one of the elements which can be doped into hydroxyapatite structure by replacing phosphate (PO43-) or hydroxyl (OH-) sites to obtain scaffolds for bone tissue engineering applications or a coating material for metal substrates. Although the effects of supplemental boron on bone, liver, and brain metabolism have been shown to have important results as a nutrient, there are very few studies in the literature on the use of boron-doped hydroxyapatite in the biomedical field. In this review, the details of synthesis methods and functional groups of boron-doped hydroxyapatite were tabulated. Generally, the addition of boron leads to the formation of rod-like morphology, while the density and Vicker’s microhardness of hydroxyapatite decrease. Thermal stability and electrical insulation properties were observed to improve with boron doping. Boron was also shown to increase biodegradability, bioactivity as well as cell proliferation and differentiation of different cell types on the surface of hydroxyapatite.