Rare earth-based materials for bone regeneration: Breakthroughs and advantages

Abstract As a remarkable strategic resource, rare earth elements (REEs) endow implantable bone regeneration materials with excellent properties both in vitro and in vivo, including optimizing mechanical properties, making materials visual, inducing cells responses and regulating local microenvironment, etc., which have aroused widespread attention in the forefront of biomedical fields and materials science. In this review, a comprehensive survey of the breakthroughs and advantages about rare earth (RE)-based bone regeneration materials is provided. By interacting with RE-based materials, the biological responses of cells involved in bone regeneration are activated, such as inducing gene expression, promoting angiogenesis and activating functions of immune cell. Importantly, the unique RE-based up-conversion luminescent nanoparticles and enhanced nuclear magnetic resonance imaging (MRI) functionalized gadolinium (Gd) complexes make the material and even bone-regeneration progress detected easily through a variety of imaging methods. In addition, the introduction of REEs also plays other roles in bone tissue engineering like enhancing corrosion resistance, antibacteria, anti-inflammatory, reducing oxidative stress, enhancing bone density and so on. Finally, challenges and prospects towards RE-based bone regeneration materials are discussed.