Core-shell metal-organic frameworks with fluorescence switch to trigger an enhanced photodynamic therapy

The design of hybrid metal-organic framework (MOF) nanomaterials by integrating inorganic nanoparticle into MOF (NP@MOF) has demonstrated outstanding potential for obtaining enhanced, collective, and extended novel physiochemical properties. However, the reverse structure of MOF-integrated inorganic nanoparticle (MOF@NP) with multifunction has rarely been reported. Methods: We developed a facile in-situ growth method to integrate MOF nanoparticle into inorganic nanomaterial and designed a fluorescence switch to trigger enhanced photodynamic therapy. The influence of "switch" on the photodynamic activity was studied in vitro. The in vivo mice with tumor model was applied to evaluate the "switch"-triggered enhanced photodynamic therapy efficacy. Results: A core-satellites structure with fluorescence off and on function was obtained when growing MnO₂ on the surface of fluorescent zeolitic imidazolate framework (ZIF-8) nanoparticles. Furthermore, A core-shell structure with photodynamic activity off and on function was achieved by growing MnO₂ on the surface of porphyrinic ZrMOF nanoparticles (ZrMOF@MnO₂). Both the fluorescence and photodynamic activities can be turned off by MnO₂ and turned on by GSH. The GSH-responsive activation of photodynamic activity of ZrMOF@MnO₂ significantly depleted the intracellular GSH via a MnO₂ reduction reaction, thus triggering an enhanced photodynamic therapy efficacy. Finally, the GSH-reduced Mn²⁺ provided a platform for magnetic resonance imaging-guided tumor therapy. Conclusion: This work highlights the impact of inorganic nanomaterial on the MOF properties and provides insight to the rational design of multifunctional MOF-inorganic nanomaterial complexes.