Biomimetic smart mesoporous carbon nanozyme as a dual-GSH depletion agent and O generator for enhanced photodynamic therapy.

Photodynamic therapy (PDT) has been thriving in the theranostics of cancer in recent years. However, due to a series of problems such as high concentration of GSH and insufficient O partial pressure in the tumor micro-environment, it is difficult to achieve the desired therapeutic effects with single PDT. Mesoporous carbon (MC-COOH) has been widely used in photothermal therapy (PTT) due to its high photothermal conversion efficiency and drug loading. In addition, we have discovered that MC-COOH owned high-efficiency glutathione oxidase-like activity for intracellular lasting GSH consumption. Hence, a smart mesoporous carbon nanozyme (CCM) was designed as a dual-GSH depletion agent and O generator combined with PTT to overcome the dilemma of PDT. MnO-doped carbon nanozyme (MC-Mn) was developed as the photothermal vehicles for the efficient loading of photosensitizer (Ce6). Subsequently, 4T1 membrane-coated nanozyme (Ce6/CCM) was constructed to achieve homologous targeting capability. The carbon nanozyme owned the sustained dual-GSH depletion function through MC-COOH and MnO, which greatly destroyed the antioxidant system of the tumor. Meanwhile, MnO could produce affluent O in the presence of HO, thereby alleviating the hypoxic state of tumor tissues and further promoting the generation of ROS. In addition, the novel carbon nanozyme was designed as photoacoustic imaging (PAI) agent and magnetic resonance imaging (MRI) contrast for real-time imaging during tumor therapy. In summary, this work showed that the biomimetic carbon nanozyme could be used as dual-GSH depletion agent and O generator for dual-mode imaging-guided PTT-PDT. STATEMENT OF SIGNIFICANCE: - MC-COOH with highly efficient GSH-OXD activity was first discovered and applied in PDT. - MnO acted as an O generator and GSH depletion agent to enhance PDT. - The tumor-targeting ability of the nanozyme was improved by cell membrane camouflage. - CCM nanozyme possesses both PAI and MRI dual-mode imaging modalities to guide PDT/PTT.