SYNTHESIS AND PROPERTIES OF Fe-MODIFIED CALCIUM-DEFICIENT HYDROXYAPATITE NANOCRYSTAL FOR MRI CONTRAST AGENT

Abstract

In order to achieve for a better magnetic resonance imaging (MRI) contrast agent, the synthesis, degradation and magnetic properties of Fe -modified calcium deficient hydroxyapatite nanoparticles ( Fe -CDHAP, ( Ca , Fe )10-x( HPO 4)x( PO 4)6-x( OH )2-x), which synthesizes using ultrasonic assisted precipitation at low temperature, were investigated. The MRI contrast agent should be stable, biodegradable and also with great magnetism. The synthesized sample demonstrates needle-like morphology with dimension less than 50 nm in width and 300 nm in length under SEM. The structure and crystal deformation were studied by X-ray diffraction (XRD), which show 0.2% shrinkage in cell volume, through the pattern shifting and the lattice parameters calculations. Thermal gravity analysis (TGA) analysis indicated Fe -CDHAP were stable up to 1200°C and confirmed the structure of the Fe -CDHAP, which is stable. Fourier transform infrared spectroscopy (FTIR) assisted to define the influence of iron substitution and gave the hint of internal structure variation on [Formula: see text] sites that reflect on the great amount of phosphate ions release in acidic solution. The methods above prove the structure of Fe -CDHAP and also indicate the effect to [Formula: see text], which is caused by the doping of iron ions. The degradation test confirms the biodegradability of Fe -CDHAP that can degrade faster than CDHAP and also release a great amount of phosphate ions in a short time. The magnetic property of CDHAP and Fe -CDHAP were determined with VSM to and found the transformation of diamagnetic into paramagnetic.