Luminescent hollow CaWO4 microspheres: template-free synthesis, characterization and application in drug delivery

Abstract

Luminescent porous micro/nano-structures have gained much attention in recent years due to their potential applications in biomedical fields. Herein, we report the well-dispersed luminescent hollow structural CaWO₄ microspheres prepared by a facile hydrothermal method without addition of any templates and additives. The phase, morphology and pore structures of hollow CaWO₄ microspheres were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and N₂ adsorption/desorption. It is observed that the resultant CaWO₄ microspheres possess a hollow structure with mesoporous shell and have good biocompatibility, making them suitable to be used as drug carriers. Subsequently, ibuprofen (IBU), a typical anti-inflammatory drug, was successfully loaded into the CaWO₄ microspheres and the drug release behavior was investigated. It is found that IBU molecules were successfully introduced into the inner space and mesopores of CaWO₄ microspheres and there exist strong interaction between IBU molecules and CaWO₄ microspheres. The IBU release from CaWO₄ microspheres exhibit a sustained-release property and two-step release mechanism. In addition, the hollow structural CaWO₄ microspheres also exhibit bright blue emission after loading of IBU. These results indicate that the luminescent hollow CaWO₄ microspheres have promising prospect in the sustained drug release systems and tracking drug release process.