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

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 MIT assay. The typical XRD pattern revealed characteristic phase transformation from hexagonal to rhombohedral symmetry with assembled rod shape morphology associated with size reduction ((x) over bar = 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 degrees 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.