SiO2@YBO3:Eu3+ Hollow Mesoporous Spheres for Drug Delivery Vehicle

A novel bifunctional (fluorescent, mesoporous) hollow sphere was prepared by coating luminescent YBO3:Eu(3+) nanoparticles onto uniform hollow mesoporous silica spheres (HMSs), derived from an etching strategy using spherical Fe3O4 as templates. The composites exhibit typical mesoporous shells, large interior space, high surface area, and well dispersed nanospheres with controlled size. In addition, the textural properties including the specific surface and pore volume can be easily altered by simply tuning of the spherical Fe3O4 cores. Upon ultraviolet (UV) excitation, the composite shows the characteristic (5)D0-(7)F1-4 red emission lines of Eu(3+) even after loading of the model drug. The composite with a large surface area and cavity was used as the host for loading the anticancer drug doxorubicin hydrochloride (DOX). It is observed that the multifunctional composites exhibit an obvious sustained release property and released in texture- and pH-sensitive patterns. Particularly, the down-conversion (DC) fluorescence intensity of the bifunctional vehicle increases with the release of drug molecules, making it possible to track the position and the drug release amount of the drug carrier system and to detect them by the change of fluorescence intensity.