Design and Mechanism Insight of Monodispersed AuCuPt Alloy Nanozyme with Antitumor Activity

Ru/Co-N,Zn-doped carbon nanocubes with multiple enzyme-like activities for high-efficiency glucose detection and self-supplying cascaded nanodrug in synergistic cancer therapy

Nanozyme technology is increasingly utilized in biosensing and biomedicine fields. To advancing this technology, it is pivotal for constructing high-quality nanozymes and expanding their multifunctional applications. Herein, Co nanoparticles embedded within N,Zn-doped carbon nanocubes (Co-N,Zn-CNCs) were facilely prepared by pyrolysis, followed by surface modification with Ru nanoparticles (termed Ru/Co-N,Zn-CNCs). The resultant material exhibited peroxidase (POD)-, catalase (CAT)- and glutathione oxidase (GSHOx)-mimic activities. After attachment of glucose oxidase (GOx), a bifunctional self-supply cascaded nanodrug system (Ru/Co-N,Zn-CNCs-GOx) was established. Specifically, the nanozyme based colorimetric sensor was constructed for visually glucose detection, showing a good linear relationship in a range of 10 to 2000 μM and a low detection limit of 0.61 μM. Further, the cascaded nanodrug exhibited high-efficiency for eradicating cancer cells by reactive oxygen species mediated chemodynamic therapy, hypoxia alleviation, and starvation therapy, coupled by realizing ferroptosis of the cancer cells. The versatile cascaded nanozyme shows potential applications in biosensing, cancer therapy, and beyond.

High-entropy oxide nanozyme for T1/T2 dual-mode magnetic resonance imaging guided photothermal-nanocatalytic tumor therapy

High-entropy oxides (HEOs) have attracted significant attention owing to their broad compositional tunability and high catalytic activity. However, research in this area is still in its early stages, and it is necessary to develop uniform multifunctional high-entropy nanozymes with appropriate sizes and excellent catalytic properties. In this study, we synthesized spherical high-entropy oxide composite carbon (HEO/C) nanoparticles (NPs) with a uniform distribution of particle size. The HEO/C NPs showed efficient peroxidase and catalase activities and photothermal conversion properties in the near-infrared (NIR) biological window. Compared to conventional Fe3O4/C NPs, HEO/C NPs exhibited superior NIR-enhanced enzyme-like activities in catalytic applications. Notably, we report, for the first time, that these HEO/C NPs exhibit T1/T2 dual-mode magnetic resonance imaging (MRI) capabilities, outperforming the single-mode T2 MRI performance of Fe3O4/C NPs. The combination of enzyme-like catalytic and photothermal properties, along with advanced MRI functionality, underscores the significant potential of HEO/C nanozymes for MRI-guided multimodal tumor therapy. This study opens new avenues for the application of high-entropy nanozymes in biomedicine.

Dendrimer-Entrapped CuPt Bimetallic Nanozymes for Tumor Microenvironment-Regulated Photothermal/Catalytic Therapy

Noble metal nanozymes have attracted extensive attention in tumor therapy due to their multiple enzyme-like activities for catalytic therapy and unique optical properties for photothermal therapy (PTT). However, their therapeutic efficiency may be compromised by the intricate tumor microenvironment (TME). Herein, copper-platinum (CuPt) bimetallic nanozymes were synthesized and entrapped by poly(amidoamine) dendrimers, with p-carboxybenzenesulfonamide (BS, a carbonic anhydrase IX (CA IX) inhibitor) modified on the surface and lonidamine (Lon) loaded inside to regulate TME for enhanced catalytic therapy and PTT. The formed CPL@G5-BS nanozymes could specifically target CA IX-overexpressed tumor cells and activate the cascade catalytic reaction with continuous •OH generation by the peroxidase-like property, O2 supply by the catalase-like property, and H2O2 replenishing by the superoxide dismutase-like property, thereby alleviating hypoxia and achieving chemodynamic therapy (CDT). In the TME, BS-mediated CA IX inhibition would normalize the extracellular pH to suppress metastasis while reducing the intracellular pH to boost the catalytic efficiency, and Lon-mediated mitochondrial respiration inhibition and energy metabolic disruption would elevate intracellular oxygen accumulation and downregulate heat shock protein (HSP) expression, further enhancing the PTT efficacy. Meanwhile, the excellent photothermal performance of CPL@G5-BS could amplify the multienzyme activities, and Cu2+-mediated glutathione depletion further improved the CDT efficiency. Overall, the CPL@G5-BS nanozymes can efficiently inhibit tumor growth and suppress metastasis by TME-regulated catalytic therapy and PTT.

Refining Single-Atom Catalytic Kinetics for Tumor Homologous-Targeted Catalytic Therapy

Single-atom nanozymes (SAzymes) hold significant potential for tumor catalytic therapy, but their effectiveness is often compromised by low catalytic efficiency within tumor microenvironment. This efficiency is mainly influenced by key factors including hydrogen peroxide (H2O2) availability, acidity, and temperature. Simultaneous optimization of these key factors presents a significant challenge for tumor catalytic therapy. In this study, we developed a comprehensive strategy to refine single-atom catalytic kinetics for enhancing tumor catalytic therapy through dual-enzyme-driven cascade reactions. Iridium (Ir) SAzymes with high catalytic activity and natural enzyme glucose oxidase (GOx) were utilized to construct the cascade reaction system. GOx was loaded by Ir SAzymes due to its large surface area. Then, the dual-enzyme-driven cascade reaction system was modified by cancer cell membranes for improving biocompatibility and achieving tumor homologous targeting ability. GOx catalysis reaction could produce abundant H2O2 and lower the local pH, thereby optimizing key reaction-limiting factors. Additionally, upon laser irradiation, Ir SAzymes could raise local temperature, further enhancing the catalytic efficiency of dual-enzyme system. This comprehensive optimization maximized the performance of Ir SAzymes, significantly improving the efficiency of catalytic therapy. Our findings present a strategy of refining single-atom catalytic kinetics for tumor homologous-targeted catalytic therapy.

Recent progress of noble metal-based nanozymes: structural engineering and biomedical applications

Due to their tunable catalytic activity, high chemical stability, and favorable electronic structure, noble metal-based nanozymes that can mimic important biocatalytic processes have attracted great attention. Rational structural design of noble metal-based nanozymes can endow them with excellent enzyme-like activities, enhanced sensitivity and stability, as well as unique physicochemical functionalities towards various biomedical applications such as sensing, diagnostics, and disease treatment. This review summarizes the recent progress in structural engineering of noble metal-based nanozymes and emphasizes the relationship between key structural factors of nanozymes and their enzyme-like properties in various enzyme-mimicking reactions. The diverse applications of noble metal-based nanozymes in biosensors, antibiosis, and disease treatment are further introduced. Finally, current challenges and future research directions in noble metal-based nanozymes are discussed. This review could offer scientific guidance to design and fabricate advanced nanozymes with enhanced functionality and performance towards clinical, environmental and biomedical applications.

A dual-function hyaluronic acid-encapsulated nanoplatform enables triple GSH depletion for apoptosis-ferroptosis synergistic oncotherapy

Ferroptosis has emerged as an alternative strategy to eradicate apoptosis-resistant tumor cells. However, the hypoxia and redox homeostasis in tumor microenvironment (TME) hinder effective ferroptosis induction. Herein, we report a multifunctional MnO2-nanoclusters-decorated Cu2+-doped mussel-inspired mesoporous polydopamine (CM) nanoplatform, which is further engineered by co-loading sorafenib (SRF) and indocyanine green (ICG) with the help of a cargo-loading and targeting-capable hyaluronic acid (HA) shell to obtain CMMSIH. Once accumulating in tumors, the MnO2 nanoclusters catalyze glutathione (GSH) oxidation and H2O2 decomposition to deplete intracellular GSH and alleviate hypoxia. The released SRF and exposed CM core are further devoted to inhibiting de novo GSH synthesis and scavenging endogenous GSH, respectively. This triple-modal GSH depletion inactivates intracellular glutathione peroxidase 4 (GPX4), thereby amplifying the potential for ferroptosis. Besides, the Cu2+-mediated fenton-like reaction and ICG-based photodynamic process generate abundant reactive oxygen species (ROS), further amplified by photothermal effect and MnO2-supplied oxygen of CMMSIH. This design synergistically achieves GPX4 inactivation, hypoxia alleviation and ROS accumulation, thus disrupting intracellular redox homeostasis and ultimately triggering the ferroptotic and apoptotic death of tumor cells. In vivo studies demonstrate that CMMSIH nanoplatform inhibits tumor growth without systemic toxicity, offering a promising multimodal strategy to overcome the limitations of TME.

Ligand-Driven Annular-Epitaxial Growth of CuS-Au Heterostructures as Trinity Plasmonic Nanozyme for Multimode Diagnosis of Pathogenic Bacteria

This study presents a novel method to control the site-selective growth of Au nanostars on CuS nanodisc substrate, it indicates that the surfactant ligands play a key role in the architecture control, only CTAC and homologous series with appropriate affinity to CuS can direct the annular-epitaxial growth of Au nanoparticles on the CuS, which demonstrates superior peroxidase (POD)-mimic and SERS activity. Mechanistic studies indicate that plasmon-enhanced catalytic and SERS activity can be attributed to the spatially separated CuS-Au heterostructure, which supports the light-triggered hot electron-hole pairs production and localized surface plasmon resonance hotspots. For practical biosensing, the CuS-Au heterostructures assembled lateral flow assay (LFA) was used for SERS/catalytic colorimetric/photothermal three-mode detection of Streptococcus pneumoniae and Klebsiella pneumoniae, with visually colorimetric mode at 103 CFU/mL and quantitative SERS/photothermal modes at 2-102 CFU/mL within 15 min, 15 clinical samples were used to validate the assay, the result was 100% concordant to the results of quantitative real-time PCR. This study provides a unique avenue to controllably produce plasmon-enhanced nanozyme, which can provide multi-mode signals for LFA application and meet the requirements of different scenarios.

Phase Changes of Multielemental Alloy Nanoparticles at Elevated Temperatures

Multielemental alloy (MEA) nanomaterials, such as medium and high entropy alloys, display promising catalytic performance in a range of chemical reactions due to their multicomponent structural configurations. These complex structural and chemical arrangements can be influenced by several factors, such as mechanical stress, irradiation, and high temperatures, which impact the performance of MEAs in various applications. Here, we investigated the effect of high temperatures on MEA nanoparticles composed of noble and transition metals (quaternary PtPdFeCo) at the atomic scale and found the material undergoes a series of phase transitions between solid solution and intermetallic phases at elevated temperatures ranging from room temperature to 1073 K. In contrast, the binary PtFe nanoalloy displays a one-way solid solution to intermetallic transition at these temperatures. Our findings, rationalized by density functional theory (DFT) studies, demonstrate how the varied migration energies of elements govern the solid solution to intermetallic transition and how differences in the bonding energies of elemental pairs influence the Gibbs free energy change (ΔG), which dictates the intermetallic to solid-solution transition. Overall, this work provides better guidance in the design, development, and usage of nano-MEAs for high-temperature-based applications.

Closed-loop cascade nanozyme strategy for mutually reinforced catalytic and mild-temperature photothermal therapeutic effects

Nanocatalysis coupled with photothermal therapy is a potent anti-cancer approach, yet its clinical utility is limited by low concentration of tumor substrate, redox interference, and risks of overheating normal tissues. Herein, we propose an innovative closed-loop nanozyme approach that leverages the synergistic effects of catalytic and mild photothermal therapy (mPTT) to address aforementioned challenges. The strategy features a folic acid-functionalized iron single-atom catalyst (FeNC-FA), designed to exhibit exceptional multienzymatic capabilities and an optimal photothermal response. In the system, the engineered FeNC-FA is capable of inducing reactive oxygen species (ROS) storm and depleting glutathione (GSH) in the specific tumor microenvironment (TME) to initiate ferroptosis. Concurrently, the accumulation of ROS effectively cleaves heat shock proteins (HSPs), thereby enhancing mPTT. An intriguing aspect is that the increased temperature within the TME further facilitates the conversion of H2O2 to O2, alleviating hypoxia and providing a positive feedback circuit to boost catalytic therapy. Additionally, the advanced photoacoustic (PA) imaging capabilities of FeNC-FA allow for self-monitoring of their accumulation at tumor sites, thereby guiding the mPTT process. Taken together, it provides a PA image-guided, mutually reinforced catalytic and mild photothermal synergistic tumor therapy both in vitro and in vivo. This targeted and synergistic strategy holds great promise for personalized medicine applications.

Ultra-Small Iron-Based Nanoparticles with Mild Photothermal-Enhanced Cascade Enzyme-Mimic Reactions for Tumor Therapy

Chemodynamic therapy (CDT), which utilizes the catalytic reactions of nanoparticles to inhibit tumor growth, is a promising approach in cancer therapy. However, its efficacy is limited by insufficient hydrogen peroxide (H2O2) concentration in tumor microenvironments and unsatisfactory enzymatic catalytic activity. To overcome these limitations, ultra-small iron-based (USIB) nanoparticles with cascaded superoxide dismutase (SOD)-mimic and peroxidase (POD)-mimic activities have been engineered. USIB nanoparticles initiated by SOD-mimic activity to transform superoxide anions (O2·-) into H2O2, elevating H2O2 levels in the tumor microenvironment and subsequently utilizing POD-mimic activity to convert H2O2 into the more reactive ·OH, thereby achieving the destruction of tumor cells. In addition, USIB nanoparticles possess photothermal conversion capabilities, and their enzymatic activity can be significantly enhanced under mild laser irradiation. Therefore, by addressing the issues of insufficient substrate concentration and low enzymatic catalytic activity, the therapeutic efficiency of CDT has been improved. Our research integrates the cascade catalytic reactions of nanozymes with laser irradiation, effectively inhibiting tumor growth and exhibiting outstanding biosafety, demonstrating promising therapeutic potential.

Fe/Cu Bimetallic Nanozyme Co-Assembled with 177Lu and Tanshinone for Quadruple-Synergistic Tumor-Specific Therapy

The co-loading of radionuclides and small-molecule chemotherapeutic drugs as nanotheranostic platforms using nanozymes holds tremendous potential for imaging-guided synergistic therapy. This study presents such nanotheranostic platform (177Lu-MFeCu@Tan) via co-assembling 177Lu radionuclide and tanshinone (Tan) into Fe/Cu dual-metal nanozyme (MFeCu). This platform simultaneously enables single-photon emission computed tomography (SPECT) imaging and a quadruple-synergistic tumor therapy approach, including internal radioisotope therapy (RIT), catalysis therapy, chemotherapy, and MFeCu-mediated ferroptosis and cuproptosis therapy. In this platform, the MFeCu can catalyze excessive intracellular hydrogen peroxide (H2O2) to generate radical oxygen species (ROS) and deplete glutathione (GSH). The excess of H2O2 and GSH are main factors for radioresistance and chemoresistance, reducing them can enhance chemotherapy and RIT. The generated ROS and depleted GSH further induce mitochondrial dysfunction and promote the aggregation of lipoylated dihydrolipoamide S-acetyltransferase and lipid peroxidation, causing the enhance of ferroptosis and cuproptosis. The in vitro and in vivo results demonstrate that this quadruple-synergistic approach shows significant therapeutic efficacy to complete tumor eradication and reduced recurrence in vivo. In conclusion, this work presents a promising strategy for designing SPECT imaging-guided quadruple-synergistic therapy and highlights the feasibility of developing a self-assembled radionuclide and small molecule chemotherapy drugs nanotherapeutic platform for combined treatment of cancer.

Tumor-Targeted Exosome-Based Heavy Atom-Free Nanosensitizers With Long-Lived Excited States for Safe and Effective Sono-Photodynamic Therapy of Solid Tumors

Theranostic nanosensitizers with combined near-infrared (NIR) fluorescence imaging and sono-photodynamic effects have great potential for use in the personalized treatment of deep-seated tumors. However, developing effective nanosensitizers for NIR fluorescence image-guided sono-photodynamic therapy remains a considerable challenge, including the low generation efficacy of reactive oxygen species (ROS), poor photostability, and the absence of cancer specificity. Herein, a novel heavy atom-free nanosensitizer is developed, which exhibits intense NIR fluorescence, high ROS generation efficiency, and improved aqueous stability. By conjugating a bulky and electron-rich group, 4-(1,2,2-triphenylvinyl)-1,1'-biphenyl (TPE), to the IR820 backbone, the resulting IR820 bearing TPE (IR820-TPE) effectively generates ROS via type I and II photochemical mechanisms under 808 nm laser irradiation. Moreover, TPE conjugation considerably increases the sono-photodynamic performance of IR820. To improve the intracellular delivery and tumor-targeting ability of IR820-TPE, biotin-conjugated exosome (B-Exo) is used as a natural nanocarrier. In vitro studies demonstrate the outstanding therapeutic performance of IR820-TPE-loaded B-Exo (IR820-TPE@B-Exo) in synergistic sono-photodynamic cancer therapy. In vivo studies reveal that IR820-TPE@B-Exo shows enhanced tumor accumulation, strong fluorescence signals, and effective sono-photodynamic therapeutic activity with high biosafety. This work demonstrates that IR820-TPE@B-Exo is a promising sono-phototheranostic agent for safe and targeted cancer therapy and NIR fluorescence imaging.

Progress in the Computer-Aided Analysis in Multiple Aspects of Nanocatalysis Research

Making the utmost of the differences and advantages of multiple disciplines, interdisciplinary integration breaks the science boundaries and accelerates the progress in mutual quests. As an organic connection of material science, enzymology, and biomedicine, nanozyme-related research is further supported by computer technology, which injects in new vitality, and contributes to in-depth understanding, unprecedented insights, and broadened application possibilities. Utilizing computer-aided first-principles method, high-speed and high-throughput mathematic, physic, and chemic models are introduced to perform atomic-level kinetic analysis for nanocatalytic reaction process, and theoretically illustrate the underlying nanozymetic mechanism and structure-function relationship. On this basis, nanozymes with desirable properties can be designed and demand-oriented synthesized without repeated trial-and-error experiments. Besides that, computational analysis and device also play an indispensable role in nanozyme-based detecting methods to realize automatic readouts with improved accuracy and reproducibility. Here, this work focuses on the crossing of nanocatalysis research and computational technology, to inspire the research in computer-aided analysis in nanozyme field to a greater extent.

Applications of DNA functionalized gold nanozymes in biosensing

In recent years, nanozymes have emerged as highly potential substitutes, surpassing the performance of natural enzymes. Among them, gold nanoparticles (AuNPs) and their metal hybrids have become a hot topic in nanozyme research due to their facile synthesis, easy surface modification, high stability, and excellent enzymatic activity. The integration of DNA with AuNPs, by precisely controlling the assembly, arrangement, and functionalization of nanoparticles, greatly facilitates the development of highly sensitive and selective biosensors. This review comprehensively elaborates on three core strategies for the combination of DNA with AuNPs, and deeply analyzes two widely applied enzyme activities in the field of sensing technology and the catalytic principles behind them. On this basis, we systematically summarize various methods for regulating the activity of gold nanozymes by DNA. Following that, we comprehensively review the latest research trends of DNA-Au nanozymes in the field of biosensing, with a particular focus on several crucial application areas such as food safety, environmental monitoring, and disease diagnosis. In the conclusion of the article, we not only discuss the main challenges faced in current research but also look forward to potential future research directions.

Multienzyme-like polyoxometalate for oxygen-independent sonocatalytic enhanced cancer therapy

Artificially synthesized nanozymes exhibit enzymatic activity similar to that of natural enzymes. However, in the complex tumor microenvironment, their diversity and catalytic activity show significant variations, limiting their effectiveness in catalytic therapy. Developing artificial enzymes with multiple enzymatic activities and spatiotemporal controllable catalytic abilities is of great clinical significance. Herein, we propose a novel strategy for synergistic enzyme catalysis and sonocatalytic therapy of tumors using polyoxometalates-based nanozymes. Copper-doped molybdenum-based polyoxometalates (denoted as CP) were rapidly synthesized at room temperature through a one-step method. CP contains mixed-valence states of Cu+/Cu2+ and Mo5+/Mo6+ ions, endowing it with enzyme-like activities of peroxidase, catalase, and glutathione peroxidase. Additionally, the incorporation of copper ions introduces oxygen vacancies into the nano-polyoxometalate, which not only reduces the bandgap but also enhances carrier separation efficiency, thereby improving the sonocatalytic performance of CP as a semiconductor. The combined effects of enzyme-like catalysis and sonocatalysis generate multiple reactive oxygen species (ROS), synergistically depleting glutathione (GSH) and disrupting the redox homeostasis of the tumor, inducing ferroptosis in tumor cells and thereby inhibiting tumor proliferation. This study provides new insights into the design of artificial nanozymes with multiple enzymatic activities and ultrasound activation functions for combined tumor therapy.

Bimetallic nanozymes for effectively removing Enterococcus faecalis biofilms in pulp and periapical infection treatment

Pulpal and periapical infections, primarily caused by the biofilms of Enterococcus faecalis (E. faecalis), pose significant challenges due to their resistance to eradication, making them prevalent oral health concerns. Herein, we synthesized a bimetallic Zn-Fe nanozymes (ZFNs) with enhanced peroxidase-like (POD-like) activity, capable of activating hydrogen peroxide (H2O2) into highly reactive hydroxyl radicals to combat E. faecalis biofilms. The incorporation of Zn elements effectively optimizes the electronic structure of the reactive Fe sites, significantly improving the POD-like activity of ZFNs. Consequently, a trace amount of ZFNs (20 μg mL-1) combined with H2O2 (200 μM) achieved efficient E. faecalis inactivation (95 %) and disrupts biofilm formation. Notably, in a root canal infection model, ZFNs demonstrate a biofilm-clearing effect comparable to that of 3 % sodium hypochlorite NaOCl, a clinical drug) and exhibit satisfactory biosafety. In summary, ZFNs hold promise as a root canal irrigation solution for treating pulpal and periapical infections, offering new possibilities for addressing root canal infection challenges.

Emerging Roles of Nanozyme in Tumor Metabolism Regulation: Mechanisms, Applications, and Future Directions

Nanozymes, nanomaterials with intrinsic enzyme activity, have garnered significant attention in recent years due to their catalytic abilities comparable to natural enzymes, cost-effectiveness, high catalytic activities, and stability against environmental fluctuations. As functional analogs of natural enzymes, nanozymes participate in various critical metabolic processes, including glucose metabolism, lactate metabolism, and the maintenance of redox homeostasis, all of which are essential for normal cellular functions. However, disruptions in these metabolic pathways frequently promote tumorigenesis and progression, making them potential therapeutic targets. While several therapies targeting tumor metabolism are currently in clinical or preclinical stages, their efficacy requires further enhancement. Consequently, nanozymes that target tumor metabolism are regarded as a promising therapeutic strategy. Despite extensive studies investigating the application of nanozymes in tumor metabolism, relevant reviews are relatively scarce. This article first introduces the physicochemical properties and biological behaviors of nanozymes. Subsequently, we analyze the role of nanozymes in tumor metabolism and explore their potential applications in tumor therapy. In conclusion, this review aims to foster innovative research in related fields and advance the development of nanozyme-based strategies for cancer diagnostics and therapeutics.

Multienzyme-Activity Sulfur Quantum Dot Nanozyme-Mediated Cascade Reactions in Whole-Stage Symptomatic Therapy of Infected Bone Defects

Integrating the therapeutic efficacy of early bacterial clearance, midstage inflammatory remission, and late-stage effective tissue healing is considered a pivotal challenge in symptomatic treatment of infected bone defects (IBDs). Herein, a microenvironment-adaptive nanoplatform based on a sulfur quantum dot (SQD) nanozyme was proposed for whole-stage symptomatic therapy of IBDs by mediating the sequence of enzyme cascade reactions. The SQD nanozyme prepared by a size-engineering modification strategy exhibits enhanced multienzyme activity compared to conventional micrometer- and nanometer-sized sulfur particles. In the early stages of bacterial infection, the SQD nanozyme self-activates superoxide dismutase-peroxidase activity, resulting in the production of reactive oxygen species (ROS) that effectively eliminate bacteria. After disinfection, the SQD nanozyme self-switched to superoxide dismutase-catalase mimetic behavior and eliminated excess ROS, efficiently promoting macrophage polarization to an anti-inflammatory phenotype in the midinflammatory microenvironment. Importantly, SQD nanozyme-mediated M2 macrophage polarization significantly improved the damaged bone immune microenvironment, accelerating bone repair at late-stage tissue healing. Therefore, this strategy offers a promising and viable approach for the treatment of infectious tissue healing by developing multienzyme-activity nanozymes that respond intelligently to the microenvironment at different stages, effectively fighting bacteria, reducing inflammation, and promoting tissue regeneration for whole-stage symptomatic therapy.

Engineering Dual Active Sites and Defect Structure in Nanozymes to Reprogram Jawbone Microenvironment for Osteoradionecrosis Therapy

Four to eight percent of patients with head and neck cancer will develop osteoradionecrosis of the jaw (ORNJ) after radiotherapy. Various radiation-induced tissue injuries are associated with reactive oxygen and nitrogen species (RONS) overproduction. Herein, Fe doping is used in VOx (Fe-VOx) nanozymes with multienzyme activities for ORNJ treatment via RONS scavenging. Fe doping can induce structure reconstruction of nanozymes with abundant defect production, including Fe substitution and oxygen vacancies (OVs), which markedly increased multiple enzyme-mimicking activity. Catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) enzyme-like performance of Fe-VOx can effectively reprogram jawbone microenvironment to restore mitochondrial dysfunction and enhance mitophagy. Moreover, the surface plasmon resonance (SPR) effect of Fe-VOx made it a good photothermal nanoagents for inhibiting jaw infection. Thus, this work demonstrated that Fe-VOx nanozymes can efficiently scavenge RONS, activate mitophagy, and inhibit bacteria, which is potential for ORNJ treatment.

D-Band-Center-Engineered Platinum-Based Nanozyme for Personalized Pharmacovigilance

A high-efficiency PtZnCd nanozyme was screened with density functional theory (DFT) and unique d-orbital coupling features for sensitive enrichment and real-time analysis of CO-releasing molecule-3 (CORM-3). Multicatalytic sites in the nanozyme showed a high reactivity of up to 72.89 min-1 for peroxidase (POD)-like reaction, which was 2.2, 4.07, and 14.67 times higher than that of PtZn (32.67 min-1), PtCd (17.89 min-1), and Pt (4.97 min-1), respectively. Normalization of the catalytic sites showed that the catalytic capacity of the active site in PtZnCd was 2.962 U μmol-1, which was four times higher than that of a pure Pt site (0.733 U μmol-1). DFT calculations showed that improved d-orbital coupling between different metals reduces the position of the center of the shifted whole d-band relative to the Fermi energy level, thereby increasing the contribution of the sites to the electron transfer from the active center, accompanied by enhanced substrate adsorption and intermediate conversion in the catalytic process. The potential adsorption principle and color development mechanism of CORM-3 on PtZnCd were determined, and its practical application in drug metabolism was validated in vitro and in zebrafish and mice models, demonstrating that transition-metal doping effectively engineers high-performance nanozymes and optimizes artificial enzymes.

Current advances in nanozyme-based nanodynamic therapies for cancer

Nanozymes are nano-catalysis materials with enzyme-like activities, which can repair the defects of natural enzyme such as harsh catalytic conditions, and harness their strengths to treat tumor. The emerging nanodynamic therapies improved drug selectivity and decreased drug tolerance, while causing efficient cell apoptosis through the generated reactive oxygen species (ROS). Nanodynamic therapies based on nanozymes can improve the complicated tumor microenvironment (TME) to reduce the defect rate of nanodynamic therapies, and provide more options for tumor treatment. This review summarized the characteristics and applications of nanozymes with different activities and the factors influencing the activity of nanozymes. We also focused on the application of nanozymes in nanodynamic therapies, including photodynamic therapy (PDT), chemodynamic therapy (CDT), and sonodynamic therapy (SDT). Moreover, we discussed the strategies for optimizing nanodynamic therapies based on nanozymes for tumor treatment in detail, and provided a systematic review of tactics for synergies with other tumor therapies. Ultimately, we analyzed the shortcomings of nanodynamic therapies based on nanozymes and the relevant research prospect, which would provide sufficient evidence and lay a foundation for further research. STATEMENT OF SIGNIFICANCE: 1. The novelty and significance of the work with respect to the existing literatures. (1) Recent advances in nanozyme-based nanodynamic therapies are comprehensively and systematically reviewed, and strategies to address the limitations and challenges of current therapies based on nanozymes are discussed firstly. (2) The mechanism of nanozymes in nanodynamic therapies is described for the first time. The synergistic therapies, prospects, and challenges of nanozyme-based nanodynamic therapies are innovatively discussed. 2. The scientific impact and interest to our readership. This review focuses on the recent progress of nanozyme-based nanodynamic therapies. This review indicates the way forward for the combined treatment of nanozymes and nanodynamic therapies, and lays a foundation for facilitating theoretical development in clinic.

Nanozyme as Tumor Energy Homeostasis Disruptor to Augment Cascade Catalytic Therapy

Breaking the balance of the tumor microenvironment and reshaping it sustainably remain major challenges in lung cancer treatment. Here, a "tumor energy homeostasis disruptor", the Cu2O@Au nanozyme was developed, which exhibits excellent glucose oxidase-like activity, enabling it to be used for starvation therapy and as a mimic peroxidase for chemodynamic therapy (CDT), producing •OH. Cu2O@Au nanozymes consume glucose at the tumor site to block the tumor's energy supply, produce H2O2 continuously, and lower the pH to enhance the efficiency of CDT, initiating a cascade reaction that leads to a storm of reactive oxygen species (ROS). Furthermore, Cu2O@Au nanozyme consumes glutathione and reduces the expression of the SLC7A11 (xCT) protein to decrease cancer cell uptake of cysteine, further enhancing the burst of ROS, resulting in lipid peroxidation in tumor cells and ultimately leading to ferroptosis. The excellent photothermal performance of Cu2O@Au can further enhance CDT. Additionally, Cu2O@Au nanozyme also has computed tomography (CT) and photothermal imaging capabilities. In conclusion, Cu2O@Au nanozymes, acting as tumor energy homeostasis disruptor, can effectively inhibit tumor growth and successfully achieve the synergistic effects of starvation therapy/CDT/photothermal therapy (PTT). This multifunctional nanozyme holds promise for providing valuable insights and therapeutic strategies for cancer treatment.

Hypoxia reconstructed colorectal tumor microenvironment weakening anti-tumor immunity: construction of a new prognosis predicting model through transcriptome analysis

Background

Hypoxia in the tumor microenvironment (TME) plays a pivotal role in the progression and prognosis of colorectal cancer (CRC). However, effective methods for assessing TME hypoxia remain lacking. This study aims to develop a novel hypoxia-related prognostic score (HPS) based on hypoxia-associated genes to improve CRC prognostication and inform treatment strategies.

Methods

Transcriptomic data from CRC patients were analyzed using Lasso regression to identify hypoxia-associated genes with the strongest prognostic significance. The identified genes were validated in vitro by assessing their expression under normoxic and hypoxic conditions in normal intestinal epithelial cells and CRC tumor cell lines. Functional relevance was explored through differential gene expression analysis, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, and protein-protein interaction (PPI) network construction. The association of HPS with extracellular matrix (ECM) composition, immune cell infiltration, and immune suppression was also investigated.

Results

Seven hypoxia-associated signature genes were identified, each demonstrating a strong correlation with CRC prognosis. The hypoxia-related prognostic score (HPS), derived from these genes, was significantly linked to changes in the TME. Specifically, HPS values were associated with alterations in ECM composition and distinct immune cell infiltration patterns. Higher HPS values corresponded to increased infiltration of immune-suppressive cells and reduced presence of anti-tumor immune cells. This imbalance promoted an immune-suppressive TME, facilitating tumor progression and immune evasion.

Conclusions

The hypoxia-related prognostic score (HPS) captures the regulatory influence of TME hypoxia on immune responses, offering valuable insights into its role in tumor progression. HPS holds promise as a prognostic tool and a guide for developing personalized treatment strategies in CRC.

Enzymes in Addressing Hypoxia for Biomaterials Engineering

Oxygen is essential for normal cellular functions. Hypoxia impacts various cellular processes, such as metabolism, growth, proliferation, angiogenesis, metastasis, tumorigenesis, microbial infection, and immune response, mediated by hypoxia-inducible factors (HIFs). Hypoxia contributes to the progression and development of cancer, cardiovascular diseases, metabolic disorders, kidney diseases, and infections. The potential alleviation of hypoxia has been explored through the enzymatic in situ decomposition of hydrogen peroxide, leading to the generation of oxygen. However, challenges such as limited stability restrict the effectiveness of enzymes such as catalase in biomedical and in vivo applications. To overcome these limitations, targeted delivery of the enzymes has been proposed. This review offers a critical comparison of i) current approaches to enhance the in vivo stability of catalase; and ii) the structure, mechanism of action, and kinetics of catalase and catalase-like nanozymes.

"All-in-One" MnO2@PtAuRu Nanoreactor for Self-Replenishing and Cascade Catalytic Therapy of Cancer

Limited by the insufficient catalytic substrates such as H2O2 and O2 in the tumor microenvironment (TME), the continual propelling of nanozymes catalysis therapy of cancer remains a challenge. Here, an all-in-one MnO2@PtAuRu nanoreactor is constructed for self-propelled and cascade catalytic therapy of tumors. The MnO2@PtAuRu is constructed by using hollow MnO2 (≈150 nm) as the core-carrier and ultrasmall PtAuRu nanoclusters (≈2 nm) anchoring on the surface MnO2. According to the glucose oxidase (GOD)/catalase (CAT)/peroxidase (POD) mimic multienzyme activity of PtAuRu nanoclusters, cascaded nanocatalytic reactions can be self-replenishing to persistently produce •OH for superior chemodynamic therapy (CDT). Additionally, the MnO2 carrier can protect the ultrasmall PtAuRu nanoclusters during the circulation and the overexpressed glutathione (GSH) in the tumor can also be degraded by the MnO2 to synergy the CDT. The MnO2@PtAuRu displays obvious photothermal properties which further enhance the cascade catalytic ability and synergistic therapeutic effect. Therefore, this all-in-one nanozyme provides a promising strategy for the rational design of self-replenishment and self-replenishing cascade catalytic therapy of cancer.

Photo-Activated Oxidative Stress Amplifier: A Strategy for Targeting Glutathione Metabolism and Enhancing ROS-Mediated Therapy in Triple-Negative Breast Cancer Treatment

Amplifying oxidative stress within tumor cells can effectively inhibit the growth and metastasis of triple-negative breast cancer (TNBC). Therefore, the development of innovative nanomedicines that can effectively disrupt the redox balance represents a promising yet challenging therapeutic strategy for TNBC. In this study, an oxidative stress amplifier, denoted as PBCH, comprising PdAg mesoporous nanozyme and a CaP mineralized layer, loaded with GSH inhibitor L-buthionine sulfoximine (BSO), and further surface-modified with hyaluronic acid that can target CD44, is introduced. In the acidic tumor microenvironment, Ca2+ is initially released, thereby leading to mitochondrial dysfunction and eventually triggering apoptosis. Additionally, BSO suppresses the synthesis of intracellular reduced GSH and further amplifies the level of oxidative stress in cancer cells. Furthermore, PdAg nanozyme can be activated by near-infrared light to induce photothermal and photodynamic effects, causing a burst of ROS and simultaneously promoting cell apoptosis via provoking immunogenic cell death. The high-performance therapeutic effects of PBCH, based on the synergistic effect of aforementioned multiple oxidative damage and photothermal ablation, are validated in TNBC cells and animal models, declaring its potential as a safe and effective anti-tumor agent. The proposed approach offers new perspectives for precise and efficient treatment of TNBC.

A strategy of "adding fuel to the flames" enables a self-accelerating cycle of ferroptosis-cuproptosis for potent antitumor therapy

Cuproptosis in antitumor therapy faces challenges from copper homeostasis efflux mechanisms and high glutathione (GSH) levels in tumor cells, hindering copper accumulation and treatment efficacy. Herein, we propose a strategy of "adding fuel to the flames" for potent antitumor therapy through a self-accelerating cycle of ferroptosis-cuproptosis. Disulfiram (DSF) loaded hollow mesoporous copper-iron sulfide (HMCIS) nanoparticle with conjugation of polyethylene glycol (PEG) and folic acid (FA) (i.e., DSF@HMCIS-PEG-FA) was developed to swiftly release DSF, H2S, Cu2+, and Fe2+ in the acidic tumor microenvironment (TME). The hydrogen peroxide (H2O2) levels and acidity within tumor cells enhanced by the released H2S induce acceleration of Fenton (Fe2+) and Fenton-like (Cu2+) reactions, enabling the powerful tumor ferroptosis efficacy. The released DSF acts as a role of "fuel", intensifying catalytic effect ("flame") in tumor cells through the sustainable Fenton chemistry (i.e., "add fuel to the flames"). Robust ferroptosis in tumor cells is characterized by serious mitochondrial damage and GSH depletion, leading to excess intracellular copper that triggers cuproptosis. Cuproptosis disrupts mitochondria, compromises iron-sulfur (Fe-S) proteins, and elevates intracellular oxidative stress by releasing free Fe3+. These interconnected processes form a self-accelerating cycle of ferroptosis-cuproptosis with potent antitumor capabilities, as validated in both cancer cells and tumor-bearing mice.

Engineering Strain-Defects to Enhance Enzymatic Therapy and Induce Ferroptosis

The effect of mimetic enzyme catalysis is often limited by insufficient activity and a single therapy is not sufficient to meet the application requirements. In this study, a multifunctional nanozyme, MMSR-pS-PEG, is designed and fabricated by modifying poly (ethylene glycol) grafted phosphorylated serine (pS-PEG) on mesoporous hollow MnMoOx spheres, followed by loading sorafenib (SRF) into the pores. Strain engineering-induced oxygen defects endow the nanozyme with enhanced dual-enzymatic activity to mimic catalase and oxidase-like activities, which catalyze the conversion of endogenous H2O2 into oxygen and subsequently into superoxide ions in the acidic tumor microenvironment. Moreover, as an n-type semiconductor, MnMoOx generates reactive oxygen species by separating electrons and holes upon ultrasonic irradiation and simultaneously deplete glutathione by holes, thereby further augmenting its catalytic effect. As a ferroptosis inducer, SRF restrains the system xc - and indirectly inhibits glutathione synthesis, synergistically interacting with the nanozyme to stimulate ferroptosis by promoting lipid peroxidation and accumulation and the downregulation of glutathione peroxidase 4. These results provide valuable insights into the design of enzymatic therapy with high performance and highlight a promising approach for the synergism of ferroptosis and enzymatic tumor therapy.

Dual Enzyme-Driven Cascade Reactions Modulate Immunosuppressive Tumor Microenvironment for Catalytic Therapy and Immune Activation

Lactate-enriched tumor microenvironment (TME) fosters an immunosuppressive milieu to hamper the functionality of tumor-associated macrophages (TAMs). However, tackling the immunosuppressive effects wrought by lactate accumulation is still a big challenge. Herein, we construct a dual enzyme-driven cascade reaction platform (ILH) with immunosuppressive TME modulation for photoacoustic (PA) imaging-guided catalytic therapy and immune activation. The ILH is composed of iridium (Ir) metallene nanozyme, lactate oxidase (LOx), and hyaluronic acid (HA). The combination of Ir nanozyme and LOx can not only efficiently consume lactate to reverse the immunosuppressive TME into an immunoreactive one by promoting the polarization of TAMs from the M2 to M1 phenotype, thus enhancing antitumor defense, but also alleviate tumor hypoxia as well as induce strong oxidative stress, thus triggering immunogenic cell death (ICD) and activating antitumor immunity. Furthermore, the photothermal performance of Ir nanozyme can strengthen the cascade catalytic ability and endow ILH with a PA response. Based on the changes in PA signals from endogenous molecules, three-dimensional multispectral PA imaging was utilized to track the process of cascade catalytic therapy in vivo. This work provides a nanoplatform for dual enzyme-driven cascade catalytic therapy and immune activation by regulating the immunosuppressive TME.

Engineering Sonosensitizer-Derived Nanotheranostics for Augmented Sonodynamic Therapy

Sonodynamic therapy (SDT), featuring noninvasive, deeper penetration, low cost, and repeatability, is a promising therapy approach for deep-seated tumors. However, the general or only utilization of SDT shows low efficiency and unsatisfactory treatment outcomes due to the complicated tumor microenvironment (TME) and SDT process. To circumvent the issues, three feasible approaches for enhancing SDT-based therapeutic effects, including sonosensitizer optimization, strategies for conquering hypoxia TME, and combinational therapy are summarized, with a particular focus on the combination therapy of SDT with other therapy modalities, including chemodynamic therapy, photodynamic therapy, photothermal therapy, chemotherapy, starvation therapy, gas therapy, and immunotherapy. In the end, the current challenges in SDT-based therapy on tumors are discussed and feasible approaches for enhanced therapeutic effects are provided. It is envisioned that this review will provide new insight into the strategic design of high-efficiency sonosensitizer-derived nanotheranostics, thereby augmenting SDT and accelerating the potential clinical transformation.

Three-in-One Nanozyme for Radiosensitization of Bladder Cancer

Purpose

Bladder cancer is a common malignancy of the urinary system and the development of noninvasive therapeutic methods is imperative to avoid radical cystectomy, which results in a poor quality of life for patients.

Methods

In this study, ultrasmall copper-palladium nanozymes decorated with cysteamine (CPC) nanoparticles (NPs) were synthesized to enhance the efficacy of radiotherapy (RT) in treating bladder cancer. CPC NPs react with intracellular overexpressed H2O2 in the tumor microenvironment to produce large quantities of reactive oxygen species (ROS) and induce tumor cell apoptosis. Furthermore, the CPC nanozymes can generate ample oxygen within tumors by utilizing H2O2, addressing hypoxia conditions, and mitigating radioresistance. Additionally, CPC facilitates the oxidation of glutathione (GSH) into oxidized glutathione disulfide (GSSG), blocking the self-repair mechanisms of tumor cells post-treatment. Simultaneously, CPC enhances the ionization energy deposition effect on tumor cells.

Results

The results demonstrate an increased level of ROS and an elevation in oxygen content at the tumor site. Importantly, tumor growth was restrained without apparent systemic toxicity during the combined treatment.

Conclusion

In summary, this study highlights the potential of CPC nanozyme-mediated radiotherapy as a promising avenue for the effective treatment of bladder cancer and demonstrates its potential for future clinical applications in the synergistic therapy of bladder cancer.

Dual-activity nanozyme as an oxygen pump to alleviate tumor hypoxia and enhance photodynamic/ NIR-II photothermal therapy for sniping oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most common malignant tumor in the head and neck region, and its treatment is limited by hypoxia and inadequate oxygen supply. Continuous oxygen delivery combined with photodynamic therapy (PDT) is the key to addressing this issue. Here, a dual-enzyme activity sea urchin-like Au@Pt-Ce6-HN-1 nanoplatform was designed to serve as an "oxygen pump" to alleviate tumor hypoxia for synergistic photodynamic/photothermal therapy (PTT). In this design, the photosensitizer chlorin e6 (Ce6) is covalently linked to the Au@Pt nanozyme for PDT treatment. The Au@Pt nanozyme exhibits catalase-like activity, continuously decomposing H2O2 in the tumor microenvironment to enhance O2 levels, thereby achieving efficient PDT. Furthermore, Au@Pt can perform PTT and increase oxygen levels under NIR-II light to further promote PDT. The Au@Pt nanozyme also exhibits peroxidase-like activity, generating ·OH for chemodynamic therapy (CDT). Additionally, HN-1 guides the direction of "sniping" OSCC, and its high specificity benefits Au@Pt-Ce6-HN-1 at the tumor site. Au@Pt-Ce6-HN-1 exhibits bright fluorescence (FL), strong CT signal, and photothermal imaging capabilities, laying the foundation for subsequent guided PDT/PTT. This nanoplatform, which combines advantages such as continuous oxygen production, tumor targeting, and multimodal imaging, is expected to provide valuable insights into the treatment of OSCC. STATEMENT OF SIGNIFICANCE: Accurate clinical diagnosis and treatment of OSCC are challenging. We report a dual-enzyme activity sea urchin-like Au@Pt-Ce6-HN-1 nanoplatform, serving as an "oxygen pump" to guide photodynamic therapy (PDT) and photothermal therapy (PTT) for OSCC. This nanoplatform targets OSCC for preoperative CT diagnosis and offers fluorescence visualization for surgical navigation, demonstrating potential in clinical cancer detection and surgery guidance. This innovative approach addresses OSCC hypoxia and enhances treatment efficacy through continuous oxygen production, tumor targeting, and multimodal imaging, significantly improving patient outcomes in OSCC treatment.

PdMoPtCoNi High Entropy Nanoalloy with d Electron Self-Complementation-Induced Multisite Synergistic Effect for Efficient Nanozyme Catalysis

Engineering multimetallic nanocatalysts with the entropy-mediated strategy to reduce reaction activation energy is regarded as an innovative and effective approach to facilitate efficient heterogeneous catalysis. Accordingly, conformational entropy-driven high-entropy alloys (HEAs) are emerging as a promising candidate to settle the catalytic efficiency limitations of nanozymes, attributed to their versatile active site compositions and synergistic effects. As proof of the high-entropy nanozymes (HEzymes) concept, elaborate PdMoPtCoNi HEA nanowires (NWs) with abundant active sites and tuned electronic structures, exhibiting peroxidase-mimicking activity comparable to that of natural horseradish peroxidase are reported. Density functional theory calculations demonstrate that the enhanced electron abundance of HEA NWs near the Fermi level (EF) is facilitated via the self-complementation effect among the diverse transition metal sites, thereby boosting the electron transfer efficiency at the catalytic interface through the cocktail effect. Subsequently, the HEzymes are integrated with a portable electronic device that utilizes Internet of Things-driven signal conversion and wireless transmission functions for point-of-care diagnosis to validate their applicability in digital biosensing of urinary biomarkers. The proposed HEzymes underscore significant potential in enhancing nanozymes catalysis through tunable electronic structures and synergistic effects, paving the way for reformative advancements in nano-bio analysis.

Nanozymes-Mediated Cascade Reaction System for Tumor-Specific Diagnosis and Targeted Therapy

Cascade reactions are described as efficient and versatile tools, and organized catalytic cascades can significantly improve the efficiency of chemical interworking between nanozymes. They have attracted great interest in many fields such as chromogenic detection, biosensing, tumor diagnosis, and therapy. However, how to selectively kill tumor cells by enzymatic reactions without harming normal cells, as well as exploring two or more enzyme-engineered nanoreactors for cascading catalytic reactions, remain great challenges in the field of targeted and specific cancer diagnostics and therapy. The latest research advances in nanozyme-catalyzed cascade processes for cancer diagnosis and therapy are described in this article. Here, various sensing strategies are summarized, for tumor-specific diagnostics. Targeting mechanisms for tumor treatment using cascade nanozymes are classified and analyzed, "elements" and "dimensions" of cascade nanozymes, types, designs of structure, and assembly modes of highly active and specific cascade nanozymes, as well as a variety of new strategies of tumor targeting based on the cascade reaction of nanozymes. Finally, the integrated application of the cascade nanozymes systems in tumor-targeted and specific diagnostic therapy is summarized, which will lay the foundation for the design of more rational, efficient, and specific tumor diagnostic and therapeutic modalities in the future.

Nanozymes: Classification and Analytical Applications - A Review

The recent discovery of a new class of nanomaterials called nanozymes, which have the action of enzymes and are thus of tremendous significance, has altered our understanding of these previously believed to be biologically inert nanomaterials. As a significant and exciting class of synthetic enzymes, nanozymes have distinct advantages over natural enzymes. They are less expensive, more stable, and easier to work with and store, making them a viable substitute. This practical advantage of nanozymes over natural enzymes reassures us about the potential of this new technology. Peroxidase-like nanozymes have been investigated for the purpose of creating adaptable biosensors via the use of molecularly imprinted polymers (MIPs) or particular bio recognition ligands, including enzymes, antibodies, and aptamers. This review delves into the distinctions between synthetic and natural enzymes, explaining their structures and analytical applications. It primarily focuses on carbon-based nanozymes, particularly those that contain both carbon and hydrogen, as well as metal-based nanozymes like Fe, Cu, and Au, along with their metal oxide (FeO, CuO), which have applications in many fields today. Analytical chemistry finds great use for nanozymes for sensing and other applications, particularly in comparison with other classical methods in terms of selectivity and sensitivity. Nanozymes, with their unique catalytic capabilities, have emerged as a crucial tool in the early diagnosis of COVID-19. Their application in nanozyme-based sensing and detection, particularly through colorimetric and fluorometric methods, has significantly advanced our ability to detect the virus at an early stage.

Metal nanozymes modulation of reactive oxygen species as promising strategies for cancer therapy

Nanozymes, nanostructured materials emulating natural enzyme activities, exhibit potential in catalyzing reactive oxygen species (ROS) production for cancer treatment. By facilitating oxidative reactions, elevating ROS levels, and influencing the tumor microenvironment (TME), nanozymes foster the eradication of cancer cells. Noteworthy are their superior stability, ease of preservation, and cost-effectiveness compared to natural enzymes, rendering them invaluable for medical applications. This comprehensive review intricately explores the interplay between ROS and tumor therapy, with a focused examination of metal-based nanozyme strategies mitigating tumor hypoxia. It provides nuanced insights into diverse catalytic processes, mechanisms, and surface modifications of various metal nanozymes, shedding light on their role in intra-tumoral ROS generation and applications in antioxidant therapy. The review concludes by delineating specific potential prospects and challenges associated with the burgeoning use of metal nanozymes in future tumor therapies.

Revealing the Optimization Route of Piezoelectric Sonosensitizers: From Mechanism to Engineering Methods

Piezoelectric catalysis is a novel catalytic technology that has developed rapidly in recent years and has attracted extensive interest among researchers in the field of tumor therapy for its acoustic-sensitizing properties. Nevertheless, researchers are still controversial about the key technical difficulties in the modulation of piezoelectric sonosensitizers for tumor therapy applications, which is undoubtedly a major obstacle to the performance modulation of piezoelectric sonosensitizers. Clarification of this challenge will be beneficial to the design and optimization of piezoelectric sonosensitizers in the future. Here, the authors start from the mechanism of piezoelectric catalysis and elaborate the mechanism and methods of defect engineering and phase engineering for the performance modulation of piezoelectric sonosensitizers based on the energy band theory. The combined therapeutic strategy of piezoelectric sonosensitizers with enzyme catalysis and immunotherapy is introduced. Finally, the challenges and prospects of piezoelectric sonosensitizers are highlighted. Hopefully, the explorations can guide researchers toward the optimization of piezoelectric sonosensitizers and can be applied in their own research.

Four Birds with One Stone: A Bandgap-Regulated Multifunctional Schottky Heterojunction for Robust Synergistic Antitumor Therapy upon Endo-/Exogenous Stimuli

Considering the profound impact of structure on heterojunction catalysts, the rational design of emerging catalysts with optimized energy band structures is required for antitumor efficiency. Herein, we select titanium nitride (TiN) and Pt to develop a multifunctional Schottky heterojunction named Pt/H-TiN&SRF (PHTS) nanoparticles (NPs) with a narrowed bandgap to accomplish "four birds with one stone" involving enzyo/sono/photo three modals and additional ferroptosis. The in situ-grown Pt NPs acted as electron traps that can cause the energy band to bend upward and form a Schottky barrier, thereby facilitating the separation of electron/hole pairs in exogenous stimulation catalytic therapy. In addition, endogenous catalytic reactions based on peroxidase (POD)- and catalase (CAT)-mimicking activities can also be amplified, triggering intense oxidative stress, in which CAT-like activity decomposes endogenous H2O2 into O2 alleviating hypoxia and provides reactants for sonodynamic therapy. Moreover, PHTS NPs can elicit mild photothermal therapy with boosted photothermal properties as well as ferroptosis with loaded ferroptosis inducer sorafenib for effective tumor ablation and apoptosis-ferroptosis synergistic tumor inhibitory effect. In summary, this paper proposes an attractive design for antitumor strategies and highlights findings for heterojunction catalytic therapy with potential in tumor theranostics.

A noble metal-enhanced Au@CuO heterostructure with multienzyme-mimicking activities for colorimetric detection of tannic acid

Nanozymes, serving as synthetic alternatives to natural enzymes, offer several benefits including cost-effectiveness, enzyme-like catalytic abilities, enhanced stability, adjustable catalytic activity, easy recyclability, mild reaction conditions, and environmental friendliness. Nonetheless, the ongoing quest to develop nanozymes with enhanced activity and to delve into the catalytic mechanism remains a challenge. In our research, we effectively developed Au@CuO nanocomposites (Au@CuO Nc), replicating the functions of four enzymes found in nature: peroxidase (POD), catalase (CAT), glutathione peroxidase (GPx), and oxidase (OXD). The catalytic efficiency of Au@CuO Nc for TMB oxidation (oxTMB) was approximately 4.8 times greater than that of plain Cu2O cubes, attributed to the synergistic catalytic impact between the Au element and Cu2O within Au@CuO Nc. Mechanistic studies revealed that the novel Au@CuO Nc nanozyme greatly enhances the decomposition of H2O2 to reactive oxygen species (ROS) intermediates (˙OH, ˙O2- and 1O2), resulting in increased POD-like activity of the single-component Cu2O cubes. When an antioxidant like TA was added to the chromogenic system, it converted oxTMB into a colorless form of TMB, enabling further evaluation of TA. Hence, a colorimetric sensor was developed for the rapid and precise quantitative measurement of TA, demonstrating strong linearity between 0.3 and 2.4 μM and featuring a low detection threshold of 0.25 μM. Moreover, this sensor was effectively utilized for the assessment of TA in actual tea samples. This work innovatively proposes a simplified and reliable strategy for the advanced design of highly effective Cu-based nanozymes, enhancing enzyme-like reactions for simultaneous, on-site colorimetric probing of antioxidants.

Bimetal loaded graphitic carbon nitride with synergistic enhanced peroxidase-like activity for colorimetric detection of p-phenylenediamine

In recent years, great progress has been made on the study of nanozymes with enzyme-like properties. Here, bimetallic Fe and Ni nanoclusters were anchored on the nanosheets of nitrogen-rich layered graphitic carbon nitride by one-step pyrolysis at high temperature (Fe/Ni-CN). The loading content of Fe and Ni on Fe/Ni-CN is as high as 8.0%, and Fe/Ni-CN has a high specific surface area of 121.86 m2 g-1. The Fe/Ni-CN can effectively oxidize 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2, and exhibits efficient peroxidase-like activity, leading to a 17.2-fold increase compared to pure graphitic carbon nitride (CN). Similar to the natural horseradish peroxidase (HRP), the Fe/Ni-CN nanozyme follows catalytic kinetics. The Michaelis-Menten constant (Km) value of the Fe/Ni-CN nanozyme for TMB is about 8.3-fold lower than that for HRP, which means that the Fe/Ni-CN nanozyme has better affinity for TMB. In addition, the catalytic mechanism was investigated by combination of free radical quenching experiments and density-functional theory (DFT) calculations. The results show that the high peroxidase-like activity is due to the easy adsorption of H2O2 after bimetal loading, which is conducive to the production of hydroxyl radicals. Based on the extraordinary peroxidase-like activity, the colorimetric detection of p-phenylenediamine (PPD) was constructed with a wide linear range of 0.2-30 μM and a low detection limit of 0.02 μM. The sensor system has been successfully applied to the detection of residual PPD in real dyed hair samples. The results show that the colorimetric method is sensitive, highly selective and accurate. This study provides a new idea for the efficient enhancement of nanozyme activity and effective detection of PPD by a bimetallic synergistic strategy.

Nanozymes for the Therapeutic Treatment of Diabetic Foot Ulcers

Diabetic foot ulcers (DFU) are chronic, refractory wounds caused by diabetic neuropathy, vascular disease, and bacterial infection, and have become one of the most serious and persistent complications of diabetes mellitus because of their high incidence and difficulty in healing. Its malignancy results from a complex microenvironment that includes a series of unfriendly physiological states secondary to hyperglycemia, such as recurrent infections, excessive oxidative stress, persistent inflammation, and ischemia and hypoxia. However, current common clinical treatments, such as antibiotic therapy, insulin therapy, surgical debridement, and conventional wound dressings all have drawbacks, and suboptimal outcomes exacerbate the financial and physical burdens of diabetic patients. Therefore, development of new, effective and affordable treatments for DFU represents a top priority to improve the quality of life of diabetic patients. In recent years, nanozymes-based diabetic wound therapy systems have been attracting extensive interest by integrating the unique advantages of nanomaterials and natural enzymes. Compared with natural enzymes, nanozymes possess more stable catalytic activity, lower production cost and greater maneuverability. Remarkably, many nanozymes possess multienzyme activities that can cascade multiple enzyme-catalyzed reactions simultaneously throughout the recovery process of DFU. Additionally, their favorable photothermal-acoustic properties can be exploited for further enhancement of the therapeutic effects. In this review we first describe the characteristic pathological microenvironment of DFU, then discuss the therapeutic mechanisms and applications of nanozymes in DFU healing, and finally, highlight the challenges and perspectives of nanozyme development for DFU treatment.

Platinum Nanoparticles-Enhanced Ferritin-Mn2+ Interaction for Magnetic Resonance Contrast Enhancement and Efficient Tumor Photothermal Therapy

Nanoplatforms with high Mn2+ coordination can display efficient T1 magnetic resonance imaging (MRI) contrast enhancement. Herein, an earth gravity-like method for enhanced interaction between Ferritin (Fn) and Mn2+ by the growth of platinum nanoparticles (PNs) in Fn's cage structure via a biomineralization method is first proposed. Fn has good biocompatibility and can provide a suitable growth site for PNs. PNs with negative charge have certain attraction to Mn2+ with positive charge, improving Fn's loading capacity of Mn2+ by attraction force; and thus, achieving efficient MRI contrast enhancement. In addition, PNs can be applied for efficient photothermal therapy (PTT) under near infrared ray (NIR) irradiation. Systemic delivery of this nanoplatform shows obvious MRI contrast enhancement and tumor progression inhibition after NIR irradiation, as well as no obvious side effects. Therefore, this nanoplatform has the potential to contribute to nanotheranostic for clinical transformation.

Bimetallic Cu@Ru Core-Shell Structures with Ligand Effects for Endo-Exogenous Stimulation-Mediated Dynamic Oncotherapy

Dynamic therapies, which induce reactive oxygen species (ROS) production in situ through endogenous and exogenous stimulation, are emerging as attractive options for tumor treatment. However, the complexity of the tumor substantially limits the efficacy of individual stimulus-triggered dynamic therapy. Herein, bimetallic copper and ruthenium (Cu@Ru) core-shell nanoparticles are applied for endo-exogenous stimulation-triggered dynamic therapy. The electronic structure of Cu@Ru is regulated through the ligand effects to improve the adsorption level for small molecules, such as water and oxygen. The core-shell heterojunction interface can rapidly separate electron-hole pairs generated by ultrasound and light stimulation, which initiate reactions with adsorbed small molecules, thus enhancing ROS generation. This synergistically complements tumor treatment together with ROS from endogenous stimulation. In vitro and in vivo experiments demonstrate that Cu@Ru nanoparticles can induce tumor cell apoptosis and ferroptosis through generated ROS. This study provides a new paradigm for endo-exogenous stimulation-based synergistic tumor treatment.

Transition-Metal-Based Nanozymes: Synthesis, Mechanisms of Therapeutic Action, and Applications in Cancer Treatment

Cancer, as one of the leading causes of death worldwide, drives the advancement of cutting-edge technologies for cancer treatment. Transition-metal-based nanozymes emerge as promising therapeutic nanodrugs that provide a reference for cancer therapy. In this review, we present recent breakthrough nanozymes for cancer treatment. First, we comprehensively outline the preparation strategies involved in creating transition-metal-based nanozymes, including hydrothermal method, solvothermal method, chemical reduction method, biomimetic mineralization method, and sol-gel method. Subsequently, we elucidate the catalytic mechanisms (catalase (CAT)-like activities), peroxidase (POD)-like activities), oxidase (OXD)-like activities) and superoxide dismutase (SOD)-like activities) of transition-metal-based nanozymes along with their activity regulation strategies such as morphology control, size manipulation, modulation, composition adjustment and surface modification under environmental stimulation. Furthermore, we elaborate on the diverse applications of transition-metal-based nanozymes in anticancer therapies encompassing radiotherapy (RT), chemodynamic therapy (CDT), photodynamic therapy (PDT), photothermal therapy (PTT), sonodynamic therapy (SDT), immunotherapy, and synergistic therapy. Finally, the challenges faced by transition-metal-based nanozymes are discussed alongside future research directions. The purpose of this review is to offer scientific guidance that will enhance the clinical applications of nanozymes based on transition metals.

Layered Double Hydroxide-Based PdCux@LDH Alloy Nanozyme for a Singlet Oxygen-Boosted Sonodynamic Therapy

Redox nanozymes have demonstrated tremendous promise in disrupting cellular homeostasis toward cancer therapy, but a dysfunctional competition of diverse activities makes it normally restricted by the complex tumor microenvironment (TME). As palladium nanocrystals can achieve the precise regulation of the enzyme-like activity by regulating exposed crystal planes, noble metal nanoalloys can enhance the enzyme-like activity by promoting electron transfer and enhanced active sites. Herein, bimetallic nanoalloys with optimized enzymatic activity were intelligently designed via the interaction between the Pd and layered double hydroxide, denoted as PdCux@LDH. This PdCux@LDH is able to produce long-lived singlet oxygen (1O2) with high efficiency and selectivity for ultrasound-improved cancer therapy. In addition, this PdCux@LDH nanozyme demonstrated unique surface-dependent multienzyme-mimicking activities for catalyzing cascade reactions: oxidase (OXD)- and catalase (CAT)-mimicking activities. Interestingly, ultrasound (US) stimulation can further improve the dual-enzyme-mimicking activities and impart superior reactive oxygen species (ROS) generation activity, thereby further consuming nicotinamide adenine dinucleotide (NADH) to cause mitochondrial dysfunction, resulting in a highly efficient alloy nanozyme-mediated cancer therapy. This work opens a new research avenue to apply nanozymes for effective sonodynamic therapies (SDT).

Classification and application of metal-based nanoantioxidants in medicine and healthcare

Antioxidants play an important role in the prevention of oxidative stress and have been widely used in medicine and healthcare. However, natural antioxidants have several limitations such as low stability, difficult long-term storage, and high cost of large-scale production. Along with significant advances in nanotechnology, nanomaterials have emerged as a promising solution to improve the limitations of natural antioxidants because of their high stability, easy storage, time effectiveness, and low cost. Among various types of nanomaterials exhibiting antioxidant activity, metal-based nanoantioxidants show excellent reactivity because of the presence of an unpaired electron in their atomic structure. In this review, we summarize some novel metal-based nanoantioxidants and classify them into two main categories, namely chain-breaking and preventive antioxidant nanomaterials. In addition, the applications of antioxidant nanomaterials in medicine and healthcare are also discussed. This review provides a deeper understanding of the mechanisms of metal-based nanoantioxidants and a guideline for using these nanomaterials in medicine and healthcare.