One-pot synthesis and photoluminescence properties of luminescent functionalized mesoporous SiO2@Tb(OH)3 core–shell nanospheres

Abstract

A facile one-pot synthesis method was used for the preparation of water-soluble luminescent mesoporous SiO₂@Tb(OH)₃ core–shell nanospheres. The prepared core–shell nanospheres have amorphous characteristics, with diameters in the distribution range of 105–135 nm. The results of X-ray diffraction (XRD) confirmed the non-crystalline nature of the core–shell nanospheres. Furthermore, the transmission electron microscopy (TEM) results have also revealed a typically ordered mesoporous characteristic of the nanospheres, which have a monodisperse spherical feature in addition to a porous surface and a narrow size distribution. Our optical studies have shown the characteristic emission of Tb³⁺ (⁵D₄–⁷F_j, where j = 6, 5, 4, 3, 2, 0), even after making a core–shell structure on the surface of the mesoporous silica nanoparticles, indicating that Tb³⁺ interacts with the silica framework (possibly the hydroxyl groups on the silica surface), and thus prevents aggregation among the Tb³⁺ ions, therefore efficiently enhancing the luminescence character of the nanospheres. These water-soluble luminescent mesoporous SiO₂@Tb(OH)₃ core–shell nanospheres could be highly suitable materials for optical bioprobes, protein labeling and drug-delivery, as particle sizes in the range of 50 to 300 nm are widely sought for drug delivery systems.