Tumor-Specific Multipath Nucleic Acid Damages Strategy by Symbiosed Nanozyme@Enzyme with Synergistic Self-Cyclic Catalysis

Deep Insight of Design, Mechanism, and Cancer Theranostic Strategy of Nanozymes

Since the discovery of enzyme-like activity of Fe3O4 nanoparticles in 2007, nanozymes are becoming the promising substitutes for natural enzymes due to their advantages of high catalytic activity, low cost, mild reaction conditions, good stability, and suitable for large-scale production. Recently, with the cross fusion of nanomedicine and nanocatalysis, nanozyme-based theranostic strategies attract great attention, since the enzymatic reactions can be triggered in the tumor microenvironment to achieve good curative effect with substrate specificity and low side effects. Thus, various nanozymes have been developed and used for tumor therapy. In this review, more than 270 research articles are discussed systematically to present progress in the past five years. First, the discovery and development of nanozymes are summarized. Second, classification and catalytic mechanism of nanozymes are discussed. Third, activity prediction and rational design of nanozymes are focused by highlighting the methods of density functional theory, machine learning, biomimetic and chemical design. Then, synergistic theranostic strategy of nanozymes are introduced. Finally, current challenges and future prospects of nanozymes used for tumor theranostic are outlined, including selectivity, biosafety, repeatability and stability, in-depth catalytic mechanism, predicting and evaluating activities.

Hydrogen Sulfide Gas Amplified ROS Cascade: FeS@GOx Hybrid Nanozyme Designed for Boosting Tumor Chemodynamic Immunotherapy

Chemodynamic immunotherapy that utilizes catalysts to produce reactive oxygen species (ROS) for killing tumor cells and arousing antitumor immunity has received considerable attention. However, it is still restricted by low ROS production efficiency and insufficient immune activation, due to intricate redox homeostasis in the tumor microenvironment (TME). Herein, a metalloprotein-like hybrid nanozyme (FeS@GOx) is designed by in situ growth of nanozyme (ferrous sulfide, FeS) in a natural enzyme (glucose oxidase, GOx) to amplify ROS cascade for boosting chemodynamic immunotherapy. In FeS@GOx, GOx allows the conversion of endogenous glucose to gluconic acid and hydrogen peroxide, which provides favorable increasing hydrogen peroxide for subsequent Fenton reaction of FeS nanozymes, thus reinforcing ROS production. Notably, hydrogen sulfide (H2 S) release is activated by the gluconic acid generation-related pH decrease, which can suppress the activity of endogenous thioredoxin reductase and catalase to further inhibit ROS elimination. Thus, FeS@GOx can sustainably amplify ROS accumulation and perturb intracellular redox homeostasis to improve chemodynamic therapy and trigger robust immunogenic cell death for effective immunotherapy combined with immune checkpoint blockade. This work proposes a feasible H2 S amplified ROS cascade strategy employing a bioinspired hybrid nanozyme, providing a novel pathway to multi-enzyme-mediated TME modulation for precise and efficient chemodynamic immunotherapy.

Coordination-Driven One-Step Rapid Self-Assembly Synthesis of Dual-Functional Ag@Pt Nanozyme

Realizing high-precise and adjustable regulation of engineering nanozyme is important in nanotechnology. Here, Ag@Pt nanozymes with excellent peroxidase-like and antibacterial effects are designed and synthesized by nucleic acid and metal ions coordination-driven one-step rapid self-assembly. The adjustable NA-Ag@Pt nanozyme is synthesized within 4 min using single-stranded nucleic acid as templates, and peroxidase-like enhancing FNA-Ag@Pt nanozyme is received by regulating functional nucleic acids (FNA) based on NA-Ag@Pt nanozyme. Both Ag@Pt nanozymes that are developed not only has simple and general synthesis approaches, but also can produce artificial precise adjustment and possess dual-functional. Moreover, when lead ion-specific aptamers as FNA are introduced to NA-Ag@Pt nanozyme, the Pb2+ aptasensor is successfully constructed by increasing electron conversion efficiency and improving the specificity of nanozyme. In addition, both nanozyme has good antibacterial properties, with ~100% and ~85% antibacterial efficiency against Escherichia coli and Staphylococcus aureus, respectively. This work provides a synthesis method of novelty dual-functional Ag@Pt nanozymes and successful application in metal ions detection and antibacterial agents.

A biomineralized bi-functional hybrid nanoflower to effectively combat bacteria via a glucose-powered cascade catalytic reaction

The bacterial resistance due to the abuse of conventional antibiotics is regarded as a major problem for bacterial-induced infections and chronic wound healing. There is an urgent need to explore alternative antimicrobial strategies and functional materials with excellent antibacterial efficacy. Herein, guanosine monophosphate (GMP) and glucose oxidase (GOD) were coordinated with copper ions to obtain a bi-functional hybrid nanoflower (Cu-GMP/GODNF) as a cascade catalyst for promoting antibacterial efficacy. Besides the efficient conversion of glucose to hydrogen peroxide, the produced gluconic acid by loading GOD can supply a compatible catalytic environment to substantially improve the peroxidase activity for generating more toxic reactive oxygen species (ROS). So, the glucose-powered cascade catalytic reaction effectively killed bacteria. Moreover, H₂O₂ self-supplied by glucose can reduce harmful side effects of exogenous H₂O₂. Meanwhile, the adhesion between the Cu-GMP/GODNF and the bacterial membrane can enhance the antibacterial efficacy. Therefore, the achieved bi-functional hybrid nanoflower exhibited high efficiency and biocompatibility for killing bacteria in diabetes-related infections.

Size-optimized nuclear-targeting phototherapy enhances the type I interferon response for "cold" tumor immunotherapy

There is growing interest in the effect of innate immune silencing in "cold" tumors, which always fail in the immune checkpoint blockade monotherapy using PD-L1 monoclonal antibodies (aPD-L1). Combination of aPD-L1 with photodynamic therapy, i.e., photoimmunotherapy, is a promising strategy to improve the mono immunotherapy. Nuclear-targeting nanoparticles could elicit a type I interferon (IFN)-mediated innate immune response and reverse the immunosuppressive microenvironment for long-term immunotherapy of "cold" tumors. Photosensitizers such as zinc phthalocyanine (ZnPc) have limited ability to target the nucleus and activate innate sensing pathways to minimize tumor recurrence. Additionally, the relationship between nanoparticle size and nuclear entry capacity remains unclear. Herein, graphene quantum dots (GQDs) were employed as aPD-L1 and ZnPc carriers. Three particle sizes (200 nm, 32 nm and 5 nm) of aPD-L1/ZnPc/GQD-PEG (PZGE) were synthesized and tested. The 5 nm nanoparticles achieved the best nuclear enrichment capacity contributing to their ultrasmall size. Notably, 5 nm PZGE-based photodynamic therapy enabled an amplification of the type I IFN-mediated innate immune response and could convert "immune-cold" tumors into "immune-hot" ones. Utilizing their size advantage to target the nucleus, 5 nm nanoparticles induced DNA damage and activated the type I IFN-mediated innate immune response, subsequently promoting cytotoxic T-lymphocyte infiltration and reversing negative PD-L1 expression. Furthermore, the nanoplatform we designed is promising for the effective suppression of distant oral squamous cell carcinoma. Thus, for the first time, this study presents a size design strategy for nuclear-targeted photo-controlled immune adjuvants and the nuclear-targeted phototherapy-mediated immunomodulatory functions of type I IFN innate immune signalling for "immune-cold" tumors. STATEMENT OF SIGNIFICANCE: The potential of commonly used photosensitizers to activate innate sensing pathways for producing type I IFNs is limited due to the lack of nuclear targeting. Facilitating the nuclear-targeting of photosensitizers to enhance innate immune response and execute long-term tumor killing effect would be a promising strategy for "cold" tumor photoimmunotherapy. Herein, we report an optimal size of PZGE nanoparticles that enable the nuclear-targeting of ZnPc, which reinforces the type I IFN-mediated innate immune response, synergistically reversing "cold tumors" to "hot tumors" for effective primary and distant tumor photoimmunotherapy. This work highlights the marked efficacy of ultrasmall nuclear-located nanocarriers and offers new insight into "immune-cold tumors" via prominent innate immune activation mediated by nuclear-targeting photoimmunotherapy.

A Calcium Fluoride Nanozyme for Ultrasound-Amplified and Ca2+ -Overload-Enhanced Catalytic Tumor Nanotherapy

The anticancer mechanism of nanozymes is dominantly associated with the capacity for generation of reactive oxygen species (ROS) caused by the valence change of metal elements. However, very little research is focused on and has achieved the exploration and development of enzyme-mimicking activities of valence-invariable metal compounds. Herein, a distinct valence-invariable calcium fluoride (CaF₂ ) nanozyme with ultrasound (US)-enhanced peroxidase (POD)-mimicking activity is rationally designed and engineered for efficient calcium (Ca²⁺ )-overload-enhanced catalytic tumor nanotherapy, which is the first paradigm of Ca-based nanozymes for catalytic cancer treatment. The release of exogenous Ca²⁺ ions from CaF₂ nanocrystals and deleterious ROS generation derived from US-amplified POD-mimicking properties facilitate intracellular Ca²⁺ accumulation and achieve Ca²⁺ -overload-induced mitochondrial dysfunction through introducing exogenous Ca²⁺ ions and regulating calcium-pumping channels of neoplastic cells. Especially, US as an exogenous energy input is capable of substantially amplifying POD-mimicking catalytic activities of CaF₂ nanozyme, ultimately achieving efficient anti-neoplastic outcome on both 4T1 breast tumor and H22 hepatic carcinoma animal models. Such a discovery of enzyme-like activity of valence-invariable metal compounds can broaden the cognition scope of nanozymes and effectively serves the field of catalytic and chemoreactive nanomedicine.

Glucose Metabolism Intervention-Facilitated Nanomedicine Therapy

Ordinarily, cancer cells possess features of abnormally increased nutrient intake and metabolic pathways. The disorder of glucose metabolism is the most important among them. Therefore, starvation therapy targeting glucose metabolism specifically, which results in metabolic disorders, restricted synthesis, and inhibition of tumor growth, has been developed for cancer therapy. However, issues such as inadequate targeting effectiveness and drug tolerance impede their clinical transformation. In recent years, nanomaterial-assisted starvation treatment has made significant progress in addressing these challenges, whether as a monotherapy or in combination with other medications. Herein, representative researches on the construction of nanosystems conducting starvation therapy are introduced. Elaborate designs and interactions between different treatment mechanisms are meticulously mentioned. Not only are traditional treatments based on glucose oxidase involved, but also newly sprung small molecule agents targeting glucose metabolism. The obstacles and potential for advancing these anticancer therapies were also highlighted in this review.

"Four-in-One" Nanozyme and Natural Enzyme Symbiotic System of Cu2-x Se-GOx for Cervical Cancer Therapy

Cervical cancer, as a common malignant tumor of the reproductive system, seriously threatens women's life and health, and is difficult to be cured by traditional treatments, such as surgery, chemotherapy and radiotherapy. Fortunately, tumor microenvironment (TME)-activated catalytic therapy with high efficiency and reduced off-target toxicity has emerged as a novel treatment model. Herein, we designed a "four-in-one" nanozyme and natural enzyme symbiotic system of Cu_2-x Se-GOx for TME-triggered cascaded catalytic enhanced cancer treatment. In response to unique TME, Cu_2-x Se with catalase activity could effectively catalyze over-expressed H₂ O₂ in cancer cells into O₂ . Subsequently, the glucose oxidase (GOx) could deplete intracellular glucose with the assistance of O₂ ; this not only achieves starvation therapy, but also regenerates H₂ O₂ to boost the generation of highly cytotoxic ^. OH due to the peroxidase activity of Cu_2-x Se. Moreover, although the free-radical scavenger glutathione (GSH) is overexpressed in tumor cells, Cu_2-x Se with glutathione oxidase activity could effectively consume GSH for enhanced ROS production. Thus, the "four-in-one" nanozyme@natural enzyme symbiotic system of Cu_2-x Se-GOx could induce significant ROS accumulation at the tumor regions, thus providing a potential approach for the treatment of cervical cancer.