Effect of Tb/Mg doping on composition and physical properties of hydroxyapatite nanoparticles for gene vector application

Transfection efficiency of hydroxyapatite nanoparticles (HAnps) is relative to the particle size, morphology, surface charge, surface modifier and so on. This study prepared HAnps with doped Tb/Mg by hydrothermal synthesis method (HTSM) and investigated the effects of different Tb/Mg contents on the morphology, particle size, surface charge, composition and cellular endocytosis of HAnps. The results showed that Mg-HAnps possessed better dispersion ability than Tb-HAnps. With increasing doping content of Tb/Mg-HAnps, the granularity of Tb-HAnps increased, while that of Mg-HAnps declined. Both particle size and zeta potential of Mg-HAnps were lower than those of Tb-HAnps. 7.5% Mg-doping HAnps presented relatively uniform slender rod morphology with average size of 30 nm, while 10% Mg-doping HAnps were prone to agglomeration. Moreover, Mg-HAnps-GFP (green fluorescent protein) endocytosed by MG63 cells was dotted in the perinuclear region, while Tb-HAnps were more likely to aggregate. In conclusion, as gene vectors, Mg-HAnps showed enhanced properties compared to Tb-HAnps.