Facile fabrication of phase transformed cerium (IV) doped hydroxyapatite for biomedical applications – A health care approach

Abstract The present study confronts instantaneous and consistent phase transformation of Hydroxyapatite (HAP) to cerium substituted Hydroxyapatite (Ce-HAP) nanoparticles using the sol-gel method. Ce3+ ions at varying concentrations from 0.01 - 0.1 M were substituted in HAP structure and analyzed using spectroscopic and electron microscopic techniques. The mechanical property acquired, and the elemental composition was determined using a Vickers hardness test and x-ray photoelectron spectroscopy (XPS). Secondly, the bio-potential was evaluated against Gram-positive and negative strains by agar diffusion method and in vitro biocompatibility studied using MG-63 cell model adapting MTT assay. The typical XRD pattern revealed characteristic phase transformation from hexagonal to rhombohedral symmetry with assembled rod shape morphology associated with size reduction (x = 40–60 nm) evidenced from electron microscopic study. The elemental composition analyzed using X-ray spectroscopy (XPS) showed the presence of P, Ca and O in addition to Ce substantiating its successful assembly into HAP lattice. This phase transformed assemblage could withstand temperature up to 800 °C, maintaining its rhombohedral symmetry with utmost stability. The key parameters viz. solubility and resorbability along with pH determined the fate of Ce-HAP nano-assemblage. Alongside, this Ce-HAP nanocomposite induced the deposition of calcium-rich apatite layers, on the surface of simulated body fluid (SBF) mimicking the hardness exhibited by bones. There was a significant antibacterial effect as determined from the size of the zone of inhibition. Notably, the drug release profile investigated using leaching studies revealed that assemblage with 0.1 M Ce showed 100% release within 40 h on a par with other concentrations. It also revealed the excellent photocatalytic activity of MB at 0.1 M concentration. Biocompatibility studies on MG-63 cells exposed to Ce-HAP nanocomposite projected cellular viability up to 70% over 72 h suggesting its atoxic potential for use in clinical reality.