Multifunctional protein-based self-assembled nanoplatform: overcoming hypoxic tumor microenvironment for enhanced imaging-guided photodynamic therapy

Catalase-positive Staphylococcus epidermidis based cryo-millineedle platform facilitates the photo-immunotherapy against colorectal cancer via hypoxia improvement

The synergistic anti-tumor impact of phototherapy and a cascading immune response are profoundly limited by hypoxia and a weakened immune response. Intravenous and intratumoral injection of therapeutic drugs also cause pain, rapid drug clearance and low utilization rates. Here, a novel cryo-millineedle platform for intratumoral delivery of a phototherapy system, S.epi@IR820, is developed in this work, combining the properties of Staphylococcus epidermidis (S. epidermidis) and IR820 for photo-immunotherapy of colorectal cancer. In this cryo-millineedle platform, S. epidermidis enhances the near-infrared absorption and light stability of IR820 and catalyzes the decomposition of H2O2 into O2 via an endogenous catalase to relieve tumor hypoxia, improve phototherapy and enhance immunogenic cell death (ICD). More interestingly, the native immunogenicity of S. epidermidis and ICD elicited by phototherapy achieved a potent anti-tumor immune response. To the best of our knowledge, this is the first study to utilize native S. epidermidis to relieve hypoxia and facilitate phototherapy. Both in vitro and in vivo experiments showed that the millineedle based phototherapy system can efficiently catalyse the decomposition of H2O2 into O2, facilitate phototherapeutic killing of CT26 tumor cells by S.epi@IR820 and enhance ICD, thus successfully activated the immune response and achieved the photo-immunotherapy against colorectal cancer. In conclusion, this study provides a novel strategy for enhanced anti-tumor efficiency of photo-immunotherapy, and develops an effective method for orthotopic administration of tumors.

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 via 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.

Enzyme-responsive design combined with photodynamic therapy for cancer treatment

Photodynamic therapy (PDT) is a noninvasive cancer treatment that has garnered significant attention in recent years. However, its application is still hampered by certain limitations, such as the hydrophobicity and low targeting of photosensitizers (PSs) and the hypoxia of the tumor microenvironment. Nevertheless, the fusion of enzyme-responsive drugs with PDT offers novel solutions to overcome these challenges. Utilizing the attributes of enzyme-responsive drugs, PDT can deliver PSs to the target site and selectively release them, thereby enhancing therapeutic outcomes. In this review, we spotlight recent advances in enzyme-responsive materials for cancer treatment and primarily delineate their application in combination with PDT.