Effect of mechanical milling time on preparation characteristic, magnetic behaviour and in-vivo study of hematite-hydroxyapatite nanocomposite

Abstract

Bovine bone is one of the natural resources of hydroxyapatite (BHAp). It also has been commercialized in the market due to its biocompability and better osseointegration. However, there has been reported of poor mechanical properties of BHAP which lead to premature fracture in implants. The combination of hematite (a-Fe2O3) and BHAp were taking into consideration to improve the mechanical properties and enhance its bioactivity. Mechanical milling was employed to fabricate the nanocomposite that occupied dispersion of metallic, generation and migration of defects in the microstructure and plastic deformation of particle. The aim of this project is to explore how milling time effects the structural features as strengthening mechanisms. Hematite substituted BHAp magnetic nanoparticle was prepared by mechanical activation (ball-milling). Synthesizing of BHAp composite showed dispersion of particles and improved strength, as it engaged to nanocrystalline metal. Effect Fe content (5%, 15% and 30%), milling time (3, 6, 9 and 12 h) before and after annealed for 2 h at 900 oC were investigated. Comprehensive characterization techniques including X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy were used to examine effect Fe3+ on structural properties such as lattice parameter of BHAp, crystallinity and morphology of the phase. Compression strength and Young’s modulus of the nanocomposites were found increased at 36.29% and 26.15% respectively, as the milling was prolonged from 3 to 12 h. Immersion studies in simulated body fluid (SBF) showed better bioactivity but different mechanism on the growth of apatite at different milling time due to surface properties and microstructure. Different magnetic properties exhibited at different milling time in 30% a-Fe2O3+BHAp due to the arrangement of Fe ion in BHAp structure. Based on the extraction assay for cytotoxicity test, the presence of higher Fe3+ ion substitution in BHAp has enhanced the cell proliferation on fibroblast with better adhesion of osteoblast on the surface until 14 days. The preliminary in-vivo studies on rat show better osseointegration for 12 h milling of 30% a-Fe2O3+BHAp indicated by callus formation after 30 days. Finally, morphology of 30% a-Fe2O3-+HAp particles behaviour strongly influenced by the milling time that regenerated new performance in bone-implant material.