Near-infrared persistent luminescence hollow mesoporous nanospheres for drug delivery and in vivo renewable imaging

The design and fabrication of trackable drug carriers is of great importance for tracking the route of drug delivery in vivo. Here, we report novel stick-shell structure, near-infrared (NIR) persistent luminescence hollow mesoporous (ZnGa2O4:Cr3+@HMS) nanospheres. Due to the hollow mesoporous SiO2 skeleton structure, the prepared nanospheres possess a high Brunauer-Emmett-Teller (BET) surface area of 514 m(2) g(-1) and a pore volume of 1.16 cm(3) g(-1), which make these nanospheres ideal drug carriers for drug loading and sustained release. In addition, these nanospheres exhibit strong NIR emission at 696 nm, and their NIR persistent luminescence can persist for more than three hours after excitation. Thus, we can realize autofluorescence-free and long-term tracking of the transport routes of drug carriers by using the exceptional properties of NIR persistent luminescence of nanospheres. More importantly, we found that the NIR persistent luminescence of ZnGa2O4:Cr3+@HMS nanospheres can be repeatedly excited by a 655 nm LED lamp. Thus, the drug transport route can be tracked for an extended time with high sensitivity in deep tissue via the method of in situ repeatable excitation. Our results indicate that the ZnGa2O4:Cr3+@HMS nanospheres combine the advantages of high drug storage capacity and excellent NIR persistent luminescence, and they show potential for application as trackable drug carriers.