A dual factor activated metal-organic framework hybrid nanoplatform for photoacoustic imaging and synergetic photo-chemotherapy.

Metal organic frameworks (MOFs) have attracted great interest as a smart drug delivery platform in the battle against cancer for their intriguing properties, such as high drug loading efficiency and microenvironment responsive degradation. Hence, the development of multifunctional MOFs integrating several theranostic elements is of crucial importance. In this work, we constructed a theranostic nanoplatform (DOX/Pd@ZIF-8) based on metal-organic frameworks encapsulating 2D Pd nanosheets and DOX using an all-in-one strategy, taking the advantages of the smart drug delivery function of MOFs and the excellent optical properties of Pd nanosheets. Polydopamine (PDA) was then introduced (DOX/Pd@ZIF-8@PDA) to improve the biocompatibility. DOX/Pd@ZIF-8@PDA exhibited excellent photothermal conversion effects and optoacoustic effects due to the strong NIR light absorption of Pd nanosheets. DOX was released in a pH-dependent manner and the release rates were accelerated in acidic solutions. However burst drug release in a relatively short period could be achieved upon 808 nm laser irradiation. Moreover, the potential of DOX/Pd@ZIF-8@PDA implemented as photoacoustic imaging contrast agents in vitro and in vivo was fully exploited and dual factor activated synergetic photo-chemo cancer therapy was successfully carried out.