Doping gadolinium versus lanthanum into hydroxyapatite particles for better biocompatibility in bone marrow stem...

Lanthanide ions (Ln³⁺) doped hydroxyapatite (HAP) particles are well established in biomedical areas. Although Ln elements are closely located in the periodic table and have plenty of similar characteristics, the minor differences in the effective ionic radii could cause alterations in the physicochemical and biological properties of HAP substitutes. The present study synthesized lanthanum-(La-) and gadolinium-(Gd-) doped HAP particles (La-HAP and Gd-HAP). And the effects of two types of particles on bone marrow stem cells (BMSCs) viability were also measured and compared in vitro. The results indicated that the Gd-HAP adsorbed more serum proteins from culture media and inhibited the new layer of apatite formation on its surface when comparing to La-HAP with a similar crystalline structure, particle size, and Zeta potential. These surface modifications can significantly reduce the cell adhesion of Gd-HAP, simultaneously decreasing the Gd-HAP particle uptake efficiency. Moreover, the cell viability of Gd-HAP remained higher than that of La-HAP in culture periods. We concluded that a slight variation in the effective ionic radii between Gd³⁺ and La³⁺ could alter the adsorption of serum proteins on the particles' surface, modulating subsequent cellular responses. The present work provides an interesting view that Gd-HAP is endowed with better cellular biocompatibility than La-HAP.