Persistent luminescent metal-organic frameworks with long-lasting near infrared emission for tumor site activated imaging and drug delivery.

Luminescent porous materials have been widely used in biosensing, bioimaging and drug delivery by virtue of the special porous structure and luminescent property. The main obstacle for the application in biosensing and bioimaging is the background interference of external irradiation. Herein, we report a background interference-free persistent luminescent metal-organic framework (PLMOF) with persistent luminescent near infrared (NIR) luminescence for tumor site activated persistent luminescence imaging. The PLMOF (PLNPs@ZIF-8) was prepared by in-situ growth of MOF on the persistent luminescent nanoparticles (PLNPs) via a surface adsorption induced self-assembly method. The PLMOF possessed NIR persistent luminescence and renewable NIR luminescence and thus enabled deep-tissue and long-term imaging without external excitation. Specifically, the PLMOF showed acidic tumor site activated persistent luminescence for in vitro and in vivo tumor imaging, which was also help to reduce the background interference. The mechanism of acidic activation was attributed to the protonation of imidazole that induces disassembly of ZIF-8. In addition, the PLMOF presented a high anti-cancer drug loading capacity, acidity-responsive drug release behavior, and significant anti-tumor effect. All these results indicate that our PLMOF can serve as a promising theranostic platform for precision medicine.