One-pot fabrication of a polydopamine-based nanoplatform for GSH triggered trimodal ROS-amplification for cancer therapy

Copper-Doped Polydopamine Nanoparticles-Mediated GSH/GPX4-Depleted Ferroptosis and Cuproptosis Sensitizes Lung Tumor to Checkpoint Blockade Immunotherapy

Immune checkpoint blockade (ICB) therapy offers hope for improved outcomes in lung cancer treatment, but its effectiveness is restricted by the presence of an immunosuppressive tumor microenvironment (TME), resulting in a limited response rate (< 20%). Here this study reports a tumor-site glutathione (GSH)/glutathione peroxidase (GPX4) dual-depletion strategy to induce tumor ferroptosis and amplify cuproptosis via a GSH-responsive polydopamine-based hybrid nanoparticle (termed CACuPDA). This approach triggers cellular lysis to reverse immunosuppressive TME and further enhance the therapeutic efficacy of lung tumors combined with anti-PD-L1-based ICB therapy. The released cinnamaldehyde (CA) can stimulate reactive oxygen species production, while Cu2+ can directly deplete GSH and suppress GPX4. Interestingly, Cu2+ induces cuproptosis by downregulating ferredoxin (FDX1) expression, whereas reduced Cu+ can catalyze hydroxyl radicals (·OH) generation from overexpressed H2O2 at the tumor site. The redox imbalance amplifies ferroptosis and cuproptosis in lung tumor cells, releasing substantial amounts of cellular contents into the immunosuppressive TME, as evidenced by an increased amount of cytotoxic T cells and a decreased amount of immunosuppressive Treg cells. In addition, in vivo experimental results revealed that CACuPDA enhanced the therapeutic effect of anti-PD-L1 by about fivefold for lung tumor treatment, providing a promising strategy to improve ICB therapy for lung tumors.

Seeding Janus Zn-Fe Diatomic Pairs on a Hollow Nanobox for Potent Catalytic Therapy

Dual atomic nanozymes (DAzymes) are promising for applications in the field of tumor catalytic therapy. Here, integrating with ultrasmall Fe5C2 nanoclusters, asymmetric coordination featuring Janus Zn-Fe dual-atom sites with an O2N2-Fe-Zn-N4 moiety embedded in a carbon vacancy-engineered hollow nanobox (Janus ZnFe DAs-Fe5C2) was elaborately developed. Theoretical calculation revealed that the synergistic effects of Zn centers acting as both adsorption and active sites, oxygen-heteroatom doping, carbon vacancy, and Fe5C2 nanoclusters jointly downshifted the d-band center of Fe 3d orbitals, optimizing the desorption behaviors of intermediates *OH, thereby significantly promoting catalytic activity. Upon 1064 nm laser irradiation, Janus ZnFe DAs-Fe5C2 with superior photothermal conversion efficiency (η = 62.5%) showed thermal-augmented catalytic therapy. Fascinatingly, Janus ZnFe DAs-Fe5C2 with multienzymatic properties can suppress the expression of glutathione peroxidase 4 and accelerate the accumulation of lipid peroxides, through which ferroptosis is triggered. Overall, tannin-involved asymmetric Janus ZnFe DAs-Fe5C2 will inspire more inventions of biodegradable DAzymes for tumor therapy application.

Metal-Coordinated Polydopamine Structures for Tumor Imaging and Therapy

Meticulously engineered nanomaterials achieve significant advances in the diagnosis and therapy of solid tumors by improving tumor delivery efficiency; and thereby, enhancing imaging and therapeutic efficacy. Currently, polydopamine (PDA) attracts widespread attention because of its biocompatibility, simplicity of preparation, abundant surface groups, and high photothermal conversion efficiency, which can be applied in drug delivery, photothermal therapy, theranostics, and other nanomedicine fields. Inspired by PDA structures that are rich in catechol and amino functional groups that can coordinate with various metal ions, which have charming qualities and characteristics, metal-coordinated PDA structures are exploited for tumor theranostics, but are not thoroughly summarized. Herein, this review summarizes the recent progress in the fabrication of metal-coordinated PDA structures and their availabilities in tumor imaging and therapy, with further in-depth discussion of the challenges and future perspectives of metal-coordinated PDA structures, with the aim that this systematic review can promote interdisciplinary intersections and provide inspiration for the further growth and clinical translation of PDA materials.

Glutathione degradable manganese-doped polydopamine nanoparticles for photothermal therapy and cGAS-STING activated immunotherapy of lung tumor

Photothermal therapy (PTT), which utilizes nanomaterials to harvest laser energy and convert it into heat to ablate tumor cells, has been rapidly developed for lung tumor treatment, but most of the PTT-related nanomaterials are not degradable, and the immune response associated with PTT is unclear, which leads to unsatisfactory results of the actual PTT. Herein, we rationally designed and prepared a manganese ion-doped polydopamine nanomaterial (MnPDA) for immune-activated PTT with high efficiency. Firstly, MnPDA exhibited 57.2% photothermal conversion efficiency to accomplish high-efficiency PTT, and secondly, MnPDA can be stimulated by glutathione (GSH) to the release of Mn2+, and it can produce ·OH in a Fenton-like reaction with the overexpressed H2O2 and stimulate the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway. These two synergistically can effectively remove lung tumor cells that have not been ablated by PTT, resulting in an 86.7% tumor suppression rate under laser irradiation of MnPDA in vivo, and further significantly activated the downstream immune response, as evidenced by an increased ratio of cytotoxic T cells to immunosuppressive Treg cells. Conclusively, the GSH degradable MnPDA nanoparticles can be used for photothermal therapy and cGAS-STING-activated immunotherapy of lung tumors, which provides a new idea and strategy for the future treatment of lung tumors.

Copper(II)-infused porphyrin MOF: maximum scavenging GSH for enhanced photodynamic disruption of bacterial biofilm

Bacterial biofilm infection is a serious obstacle to clinical therapeutics. Photodynamic therapy (PDT) plays a dynamic role in combating biofilm infection by utilizing reactive oxygen species (ROS)-induced bacterial oxidation injury, showing advantages of mild side effects, spatiotemporal controllability and little drug resistance. However, superfluous glutathione (GSH) present in biofilm and bacteria corporately reduces ROS levels and seriously affects PDT efficiency. Herein, we have constructed a Cu2+-infused porphyrin metal-organic framework (MOF@Cu2+) for the enhanced photodynamic combating of biofilm infection by the maximum depletion of GSH. Our results show that the released Cu2+ from porphyrin MOF@Cu2+ could not only oxidize GSH in biofilm but also consume GSH leaked from ROS-destroyed bacteria, thus greatly weakening the antioxidant system in biofilm and bacteria and dramatically improving the ROS levels. As expected, our dual-enhanced PDT nanoplatform exhibits a strong biofilm eradication ability both in vitro and in an in vivo biofilm-infected mouse model. In addition, Cu2+ can promote biofilm-infected wound closing by provoking cell immigration, collagen sediment and angiogenesis. Besides, no apparent toxicity was detected after treatment with MOF@Cu2+. Overall, our design offers a new paradigm for photodynamic combating biofilm infection.

Strategies to engineer various nanocarrier-based hybrid catalysts for enhanced chemodynamic cancer therapy

Chemodynamic therapy (CDT) is a newly developed cancer-therapeutic modality that kills cancer cells by the highly toxic hydroxyl radical (˙OH) generated from the in situ triggered Fenton/Fenton-like reactions in an acidic and H2O2-overproduced tumor microenvironment (TME). By taking the advantage of the TME-activated catalytic reaction, CDT enables a highly specific and minimally-invasive cancer treatment without external energy input, whose efficiency mainly depends on the reactant concentrations of both the catalytic ions and H2O2, and the reaction conditions (including pH, temperature, and amount of glutathione). Unfortunately, it suffers from unsatisfactory therapy efficiency for clinical application because of the limited activators (i.e., mild acid pH and insufficient H2O2 content) and overexpressed reducing substance in TME. Currently, various synergistic strategies have been elaborately developed to increase the CDT efficiency by regulating the TME, enhancing the catalytic efficiency of catalysts, or combining with other therapeutic modalities. To realize these strategies, the construction of diverse nanocarriers to deliver Fenton catalysts and cooperatively therapeutic agents to tumors is the key prerequisite, which is now being studied but has not been thoroughly summarized. In particular, nanocarriers that can not only serve as carriers but are also active themselves for therapy are recently attracting increasing attention because of their less risk of toxicity and metabolic burden compared to nanocarriers without therapeutic capabilities. These therapy-active nanocarriers well meet the requirements of an ideal therapy system with maximum multifunctionality but minimal components. From this new perspective, in this review, we comprehensively summarize the very recent research progress on nanocarrier-based systems for enhanced CDT and the strategies of how to integrate various Fenton agents into the nanocarriers, with particular focus on the studies of therapy-active nanocarriers for the construction of CDT catalysts, aiming to guide the design of nanosystems with less components and more functionalities for enhanced CDT. Finally, the challenges and prospects of such a burgeoning cancer-theranostic modality are outlooked to provide inspirations for the further development and clinical translation of CDT.

Bio-inspired Oxidative Stress Amplifier for Suppressing Cancer Metastasis and Imaging-Guided Combination Therapy

Antioxidant-defense systems of tumor cells protect them from oxidative damage and is strongly associated with tumor metastasis. In this work, a mussel-inspired multifunctional nanomedicine (ZS-MB@P) has been designed for inhibiting tumor growth and metastasis through amplified oxidative stress and photothermal/magnetothermal/photodynamic triple-combination therapy. This nanomedicine was fabricated via loading a silica shell on the magnetic nano-octahedrons [zinc-doped magnetic Fe₃O₄ nano-octahedrons] by encapsulating photosensitizer methylene blue (MB) and subsequently coating polydopamine (PDA) shells as "gatekeeper." The nanomedicine could realize photothermal therapy, photodynamic therapy, and magnetic hyperthermia after treatment with near-infrared (NIR) irradiation and applied magnetic field. Under pH and NIR stimulation, controlled amount of MB was released to produced exogenous reactive oxygen species. Noteworthy, PDA can amplify intracellular oxidative stress by depleting glutathione, thus inhibiting breast cancer metastasis effectively since oxidative stress is an important barrier to tumor metastasis. The outstanding ability to suppress tumor growth and metastasis was comprehensively assessed and validated both in vitro and in vivo. Moreover, the nanomedicine showed outstanding T₂ magnetic resonance imaging for tracking the treatment process. Taken together, this work offers an innovative approach in the synergistic treatment of recalcitrant breast cancer.