Long-lasting phosphorescence functionalization of mesoporous silica nanospheres by CaTiO3:Pr3+ for drug delivery

Long-lasting phosphorescence functionalization of the ordered mesoporous silica nanospheres (MSNs) was realized by depositing a CaTiO3:Pr3+ phosphor layer on its surface via the Pechini sol–gel process, resulting in the formation of the [email protected]3:Pr3+ composite material. This material, which combines the mesoporous structure of MSNs and the red long-lasting phosphorescence property of CaTiO3:Pr3+, can be used as a novel functional drug delivery system. The results indicate that a CaTiO3:Pr3+ layer can be synthesized when the annealing temperature reaches 600 °C and impurity phases start to appear when the annealing temperature reaches 800 °C or higher. The specific surface area of [email protected]3:Pr3+ decreases along with the increase of annealing temperature. The [email protected]3:Pr3+ sample synthesized at 700 °C has appropriate phosphorescence intensity and enough specific surface area (306 m2/g) to load drug molecules. The as-synthesized [email protected]3:Pr3+ composite material can be tracked in vivo by optical imaging in 12 min after peritoneal injection. The quercetin-loaded [email protected]3:Pr3+ system still shows the red phosphorescence of Pr3+ (614 nm) after UV irradiation and possesses sustained drug release property. In addition, the phosphorescence intensity of Pr3+ increases with an increase in the cumulative released amount of quercetin in the system, making the extent of drug release easily identifiable, trackable, and monitorable by the change of phosphorescence. Our research supplies a new way to fabricate in vivo visible drug delivery system.