Multifunctional nano-biosensor based on metal-organic framework for enhanced fluorescence imaging of intracellular miRNA-122 and synergistic chemo-photothermal therapy of tumor cells.

A rationally designed multifunctional polydopamine (PDA)-coated metal-organic frameworks (MOFs) biosensors for detection of miRNA-122 with Zn2+-triggered aggregation-induced enhancement (AIE) and synergistic chem-photothermal therapy in vitro was developed for the first time. Further, it was successfully used for enhanced fluorescence imaging of miRNA-122 in living cells. The pH-responsive MOFs structure was decomposed under the influence of acidic environment, and a large amount of free Zn2+ was released as the trigger agent for AIE signal amplification, realizing the ultra-sensitive detection of miRNA-122 and the accurate discrimination of the cells with different expression levels of miRNA-122, with the detection limit as low as 12.5 pM. Meanwhile, ZIF-8 nanoparticles with high loading rate can effectively deliver therapeutic drugs to achieve responsive release. In addition, the modification of versatile PDA-coating provides the biosensor with a faster drug release capability and photothermal conversion performance, demonstrating its superior synergistic chem-photothermal therapy performance. It is expected to play an important role in the integration of cancer diagnosis and synergistic therapy.