An ATP-responsive ZIF-based NIR fluorescence nanosystem for enhanced chemo-photodynamic therapy of tumors.

The combination of chemotherapy and photodynamic therapy holds immense potential for achieving synergistic anti-tumor efficacy. However, challenges such as poor stability and premature drug release prior to reaching tumor sites impede the widespread application of this synergistic therapeutic approach. In this study, a novel ATP-responsive NIR fluorescence nanosystem (CDZ) for imaging-guided chemotherapy and PDT has been developed. This nanosystem, based on ZIF-90, encapsulates the chemotherapy drug doxorubicin (DOX) and the photosensitizer asymmetrical cyanine dye Cy through self-assembly. The obtained nanosystem CDZ could efficiently avoid premature drug leakage in the blood circulation due to its high stability in the physiological environment and accumulates at the tumor sites the enhanced permeability and retention (EPR) effect. Upon uptake by tumor cells, the skeleton structure of CDZ is disrupted by overexpressed ATP levels, leading to the release of DOX, which inhibits cancer cell proliferation and induces cell death. Additionally, the released photosensitizer Cy emits strong NIR fluorescence signals, enabling real-time imaging of ATP levels in tumors. Moreover, under NIR light irradiation, this nanosystem generates high levels of ROS, achieving effective phototherapy even in deeper tumor regions. In tumor model mice, CDZ demonstrated a high rate of tumor inhibition without causing damage to major organs. This ZIF-based NIR fluorescence nanosystem, combining chemotherapy and photodynamic therapy, holds promise as a solution for treating and monitoring cancer without the associated risks of resistance and systemic toxicity.