Luminomagnetic Eu³⁺- and Dy³⁺-doped hydroxyapatite for multimodal imaging

Area of Science:

• Biomaterials Science
• Nanotechnology
• Medical Imaging

Background:

• Multimodal imaging, combining techniques like photoluminescence (PL) and magnetic resonance imaging (MRI), is gaining prominence.
• Hydroxyapatite (HAp) is a key biomaterial, but lacks inherent luminescence and magnetic properties for advanced imaging.
• Doping HAp with lanthanide ions offers a route to impart desired optical and magnetic functionalities.

Purpose of the Study:

• To synthesize and characterize luminescent and magnetic hydroxyapatite nanoparticles.
• To investigate the synergistic effects of co-doping HAp with europium (Eu³⁺) and dysprosium (Dy³⁺).
• To evaluate the potential of these multimodal nanoparticles as biocompatible agents for combined PL and MRI.

Main Methods:

• Synthesis of hydroxyapatite (HAp) nanoparticles doped with Eu³⁺ and Dy³⁺ ions.
• Characterization of crystal structure, luminescence, and magnetic properties.
• Evaluation of energy transfer mechanisms between dopant ions.
• Assessment of transverse relaxivity for MRI contrast enhancement.
• Cytocompatibility testing of the developed nanoparticles.

Main Results:

• Successfully incorporated Eu³⁺ and Dy³⁺ into the HAp crystal lattice, occupying calcium sites.
• Eu-doped HAp (Eu:HAp) showed concentration-dependent persistent photoluminescence.
• Dy-doped HAp (Dy:HAp) exhibited paramagnetic behavior.
• Co-doped HAp (Eu:Dy:HAp) nanoparticles combined both luminescence and magnetic properties.
• Enhanced PL in Eu:Dy:HAp due to energy transfer from Dy³⁺ to Eu³⁺.
• Eu:Dy:HAp demonstrated significant transverse relaxation effects with high relaxivity (83.3 L/(mmol·s)).

Conclusions:

• Co-doped Eu:Dy:HAp nanoparticles offer a single-crystal platform for multimodal imaging.
• These materials exhibit tunable photoluminescence and magnetic properties.
• The nanoparticles show promising biocompatibility for biomedical applications.
• Eu:-, Dy:-, and Eu:Dy:HAp are suitable for luminescence imaging and as MRI contrast agents for implants and coatings.