Endogenous H2O2-Sensitive and Weak Acidic pH-Triggered Nitrogen-Doped Graphene Nanoparticles (N-GNMs) in the Tumor Microenvironment Serve as Peroxidase-Mimicking Nanozymes for Tumor-Specific Treatment

Nanozymes with biomimetically designed properties for cancer treatment

Nanozymes, as a type of nanomaterials with enzymatic catalytic activity, have demonstrated tremendous potential in cancer treatment owing to their unique biomedical properties. However, the heterogeneity of tumors and the complex tumor microenvironment pose significant challenges to the in vivo catalytic efficacy of traditional nanozymes. Drawing inspiration from natural enzymes, scientists are now using biomimetic design to build nanozymes from the ground up. This approach aims to replicate the key characteristics of natural enzymes, including active structures, catalytic processes, and the ability to adapt to the tumor environment. This achieves selective optimization of nanozyme catalytic performance and therapeutic effects. This review takes a deep dive into the use of these biomimetically designed nanozymes in cancer treatment. It explores a range of biomimetic design strategies, from structural and process mimicry to advanced functional biomimicry. A significant focus is on tweaking the nanozyme structures to boost their catalytic performance, integrating them into complex enzyme networks similar to those in biological systems, and adjusting functions like altering tumor metabolism, reshaping the tumor environment, and enhancing drug delivery. The review also covers the applications of specially designed nanozymes in pan-cancer treatment, from catalytic therapy to improved traditional methods like chemotherapy, radiotherapy, and sonodynamic therapy, specifically analyzing the anti-tumor mechanisms of different therapeutic combination systems. Through rational design, these biomimetically designed nanozymes not only deepen the understanding of the regulatory mechanisms of nanozyme structure and performance but also adapt profoundly to tumor physiology, optimizing therapeutic effects and paving new pathways for innovative cancer treatment.

Picomolar glutathione detection based on the dual-signal self-calibration electrochemical sensor of ferrocene-functionalized copper metal-organic framework via solid-state electrochemistry of cuprous chloride

Chemical biosensing techniques are essential for food analysis and disease diagnosis. Nanomaterials with redox activity show great potential in electrochemical analysis, acting as signal labels or signal amplification unit, which can reflect the targets concentration in foods and biological samples. Here, an ultra-sensitive dual-signal intrinsic self-calibration electrochemical platform for GSH was firstly fabricated based on the novel electroactive nanomaterial of ferrocene-functionalized copper metal-organic framework (Fc-Cu-MOF). Due to the solid-state electrochemical property of cuprous chloride (CuCl), a sharp characteristic peak with an increased signal appears with the coexistence of chloride ions in solution. The stronger specific affinity between Cu⁺ and GSH than that of Cu⁺ and Cl^- triggers a "crowding effect" that causes the current signal of CuCl decrease greatly. Meanwhile, the peak current of ferrocene keeps unchanged as an internal reference. Based on the ratio of the peak current variation (ΔI_Cu/ΔI_Fc) as the signal output, Fc-Cu-MOF modified electrode showed wider linear range in 0.1 nM -1 μM for GSH with the detection limit as low as 0.025 nM. And the sensor was successfully applied in the determination of GSH with excellent recoveries in various real samples such as food and serum samples, providing good prospect in application of bioanalysis and food screening.

Mesoporous peroxidase nanozyme for synergistic chemodynamic therapy and chemotherapy

Peroxidase nanozyme, enabling decomposition of hydrogen peroxide (H₂O₂) into highly toxic hydroxyl radical (•OH), is an emerging technology for tumor treatment. However, limited by the low H₂O₂ level in the tumor microenvironment, the standalone peroxidase nanozyme-mediated therapy usually fails to achieve desirable therapeutic outcomes. Herein, we presented a mesoporous nanozyme that not only had peroxidase-like activity but also could deliver anticancer drug for synergistic tumor therapy. The nanozyme, that was, iron-doped mesoporous silica nanoparticle (FeMSN), was prepared by a sol-gel method and then a calcination treatment. The introduction of iron endowed FeMSN with peroxidase-like activity that could decompose H₂O₂ into •OH under acidic condition for chemodynamic therapy of tumors. Meanwhile, the mesoporous structure enabled FeMSN to deliver anticancer drug doxorubicin (DOX) for chemotherapy and enhanced chemodynamic therapy through H₂O₂ production, ultimately achieving synergistic effect to improve the efficacy of tumor treatment. The in-vitro and in-vivo results demonstrated that DOX-loaded FeMSN exhibited significant cancer cell-killing effect and potently inhibited tumor growth. Collectively, this study represented a paradigm for achieving efficient tumor therapy through design of peroxidase-like nanozyme with drug delivery capability, which might advance the development of nanozyme in tumor chemodynamic therapy.

Nanozymes-Hitting the Biosensing "Target"

Nanozymes are a class of artificial enzymes that have dimensions in the nanometer range and can be composed of simple metal and metal oxide nanoparticles, metal nanoclusters, dots (both quantum and carbon), nanotubes, nanowires, or multiple metal-organic frameworks (MOFs). They exhibit excellent catalytic activities with low cost, high operational robustness, and a stable shelf-life. More importantly, they are amenable to modifications that can change their surface structures and increase the range of their applications. There are three main classes of nanozymes including the peroxidase-like, the oxidase-like, and the antioxidant nanozymes. Each of these classes catalyzes a specific group of reactions. With the development of nanoscience and nanotechnology, the variety of applications for nanozymes in diverse fields has expanded dramatically, with the most popular applications in biosensing. Nanozyme-based novel biosensors have been designed to detect ions, small molecules, nucleic acids, proteins, and cancer cells. The current review focuses on the catalytic mechanism of nanozymes, their application in biosensing, and the identification of future directions for the field.