In Situ Multimodality Imaging of Cancerous Cells Based on a Selective Performance of Fe²⁺-Adsorbed Zeolitic Imidazolate Framework-8

Metal-organic frameworks possess tremendous potential in biomedical areas for their particular structure. In this study, the authors explored Fe²⁺-adsorbed nanoscaled zeolitic imidazolate framework-8 (ZIF-8) for in vivo multimodal imaging of cancerous cells for early diagnosis of target cancers. The observations demonstrate that adding Fe²⁺ into the suspension of ZIF-8 can neutralize the alkalinity and lower toxicity, while the Fe²⁺-adsorbed ZIF-8 can readily transform to fluorescence ZnO and super paramagnetic Fe₃O₄ under the synergistic reaction of ROS, GSH, and acids. It is evident that the formation of the nanoclusters ZnO and Fe₃O₄ only occurred in cancerous cells and does not take place in normal cells, which can be attributed to the different ROS levels and specific micro-environment in tumor and normal cells. This raises the possibility for the Fe²⁺-adsorbed zeolitic imidazolate frameworks to act as promising agents for the in vivo multimodal imaging of cancers in their early stage.