Employing Noble Metal-Porphyrins to Engineer Robust and Highly Active Single-Atom Nanozymes for Targeted Catalytic Therapy in Nasopharyngeal Carcinoma

Construction of Sonosensitizer-Drug Co-Assembly Based on Deep Learning Method

Drug co-assemblies have attracted extensive attention due to their advantages of easy preparation, adjustable performance and drug component co-delivery. However, the lack of a clear and reasonable co-assembly strategy has hindered the wide application and promotion of drug-co assembly. This paper introduces a deep learning-based sonosensitizer-drug interaction (SDI) model to predict the particle size of the drug mixture. To analyze the factors influencing the particle size after mixing, the graph neural network is employed to capture the atomic, bond, and structural features of the molecules. A multi-scale cross-attention mechanism is designed to integrate the feature representations of different scale substructures of the two drugs, which not only improves prediction accuracy but also allows for the analysis of the impact of molecular structures on the predictions. Ablation experiments evaluate the impact of molecular properties, and comparisons with other machine and deep learning methods show superiority, achieving 90.00% precision, 96.00% recall, and 91.67% F1-score. Furthermore, the SDI predicts the co-assembly of the chemotherapy drug methotrexate (MET) and the sonosensitizer emodin (EMO) to form the nanomedicine NanoME. This prediction is further validated through experiments, demonstrating that NanoME can be used for fluorescence imaging of liver cancer and sonodynamic/chemotherapy anticancer therapy.

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.

Optimizing cancer therapy through metal organic frameworks-based nanozymes

Cancer remains a leading global health challenge, with conventional treatments facing limitations due to drug resistance and adverse effects arising from tumor heterogeneity. Nanozymes, nanomaterials mimicking natural enzymes, have emerged as promising therapeutic agents owing to their catalytic efficiency, stability, and biocompatibility. Among nanozymes, MOFs-based nanozymes are particularly attractive due to the inherent tunability of MOFs, which allows for precise control over their structure, porosity, and catalytic activity. This review comprehensively explores the recent advancements in optimizing cancer therapy through MOFs-based nanozymes. We delve into the classification of these nanozymes based on their enzyme-mimicking activities, including peroxidase, oxidase, catalase, and superoxide dismutase, and discuss their underlying catalytic mechanisms. Additionally, emerging single-atom nanozymes are discussed as a distinct category. Furthermore, we highlight the diverse therapeutic strategies employing MOFs-based nanozymes, such as starvation therapy, oxygen supply, catalytic therapy, glutathione depletion, and activation of therapeutic agents within tumor microenvironment. By exploiting the unique properties of MOFs, these nanozymes demonstrate enhanced therapeutic efficacy in various cancer treatment modalities, including chemotherapy, radiotherapy, photodynamic therapy, and sonodynamic therapy. This review underscores the significant potential of MOFs-based nanozymes as a versatile platform for developing next-generation cancer therapeutics, offering improved targeting, reduced systemic toxicity, and enhanced treatment outcomes.

Endogenous Near-Infrared Chemiluminescence: Imaging-Guided Non-Invasive Thrombolysis and Anti-Inflammation Based on a Heteronuclear Transition Metal Complex

Conventional therapy to treat thrombi (blood clots) has significant limitations: i) inflammation; ii) bleeding side effects; iii) re-embolisation, and iv) in situ thrombi that are not visible. Here it is reported that Cu2Ir nanoparticles (NPs) with a Cu-coordinated tetraphenylporphyrin (TPP) core and cyclometalated Ir(C^N)2(N^N) substituents integrate long-lived near-infrared (NIR) chemiluminescence (CL) imaging, photothermal therapy (PTT) and photodynamic therapy (PDT) for thrombolysis, with antioxidant and anti-inflammatory properties. Based on density functional theory calculations the chemiluminescent reaction site between TPP and peroxynitrite (ONOO-) is confirmed for the first time. The presence of the transition metal significantly improves the chemiluminescent properties of TPP. Upon specific activation by ONOO-, Cu2Ir NPs exhibited more than 30-fold NIR CL intensity than TPP NPs, and the luminescence lasted for 60 min allowing for precise and long-lasting dynamic tracking of thrombi. Cu2Ir NPs achieved non-invasive safe thrombolytic therapy triggered by NIR irradiation at the signaling site. 72.3% blood reperfusion is obtained for nearly complete restoration of blood flow, and re-embolism is prevented in a mouse carotid artery model. Furthermore, Cu2Ir NPs scavenged excess reactive oxygen/nitrogen species (RONS) and reduced inflammatory factors. Cu2Ir NPs hold promise as a single-molecule strategy for diagnosing and treating diseases associated with thrombosis.

Porphyrins and Their Derivatives in Cancer Therapy: Current Advances, Mechanistic Insights, and Prospective Directions

Porphyrin and its derivatives are widely used in cancer therapy due to their strong photon absorption capabilities and moderate light stability. Due to their hydrophobic nature, porphyrins with tetrapyrrolic macrocycles ease self-aggregation in physiological conditions. Instead, exploiting the C4 symmetry structure for self-assembly is beneficial to improve the bioavailability of porphyrin and its derivatives. Herein, this Review outlines porphyrin-based nanoformulations for therapeutic applications in cancer treatment. The typical pharmaceutical application of the integrated porphyrinic structure is systematically summarized, focusing on the typical synthetic methodologies and structure-functionality relationship. Additionally, therapeutic modalities (e.g., photothermal, photodynamic, and sonodynamic) and their synergy mechanism in regulated cell death are overviewed. Special attention is given to emerging technologies in nanocatalytic therapy, therapeutic vaccines, and proteolysis-targeting chimeras, which align with the trend toward personalization and minimal invasiveness in healthcare. Finally, we discuss the challenges and limitations of porphyrinic nanoformulations and explore their future directions in the healthcare sector, aiming to bridge the gap between research and practical clinical application.

Ultrasmall platinum single-atom enzyme alleviates oxidative stress and macrophage polarization induced by acute kidney ischemia-reperfusion injury through inhibition of cell death storm

Acute kidney injury (AKI), characterized by a rapid decline in renal function, is associated with impaired mitochondrial function and excessive reactive oxygen species (ROS). Therefore, the exploration of ROS scavengers provides promising new opportunities for the prevention and treatment of AKI by mitigating oxidative stress. Here, we construct an ultrasmall platinum single-atom enzyme (Pt/SAE) with multiple antioxidant enzyme activities to protect against acute kidney ischemia-reperfusion (I/R) injury. Pt/SAE not only mimics superoxide dismutase and catalase activities to convert superoxide anion into water and oxygen, but also exhibits impressive hydroxyl radical scavenging capacity, thereby reducing pro-inflammatory macrophage levels and preventing inflammation. Furthermore, Pt/SAE reduces the accumulation of Z-form DNA, which excessively accumulates following I/R damage, thus decreasing its interaction with Z-DNA binding protein 1, consequently preventing the progression of PANoptosis following I/R stress. Additionally, the downregulation of ROS levels induced by Pt/SAE suppresses lipid peroxidation, which in return preventing the progression of ferroptosis following I/R. Both in vitro and in vivo experiments confirm that Pt/SAE effectively mitigates inflammatory cell infiltration and promotes a shift in macrophage polarization from the M1-like to M2-like subtype. This study provides promising information for the development of novel SAEs as a viable treatment method for AKI.

Ruthenium Single-Atom Nanozyme Driven Sonosensitizer with Oxygen Vacancies Enhances Electron-Hole Separation Efficacy and Remodels Tumor Microenvironment for Sonodynamic-Amplified Ferroptosis

Sonodynamic therapy (SDT) has emerged as a promising noninvasive approach for tumor therapy. However, the effectiveness of traditional inorganic semiconductor sonosensitizers is hindered by rapid electron (e-) and hole (h+) recombination under ultrasonic (US) stimulation, as well as the hypoxic and reductive conditions of tumor microenvironment (TME), which limit the generation of reactive oxygen species (ROS). Herein, a ruthenium (Ru) single-atom nanozyme-driven superimposition-enhanced titanium dioxide-based sonosensitizer (Ru/TiO2-x SAE) is presented that features sufficient oxygen vacancies and high e-/h+ separation efficiency. Through synchrotron radiation-based X-ray absorption spectroscopy and extended X-ray absorption fine structure analysis it is confirmed that oxygen vacancies in TiO2-x nanoparticles promote the immobilization of single-atomic Ru, forming Ru-O₄ active sites. Density functional theory calculations demonstrate that oxygen vacancies alter the electronic structure of nanosensitizer, enhanced e-/h+ separation, increasing oxygen adsorption, and accelerating reaction kinetics under US stimulation, ultimately improving ROS production. Moreover, Ru/TiO2-x SAE boosts sonodynamic efficacy by mitigating the hypoxic and reductive TME. This is attributed to its catalase- and glutathione peroxidase 4-like activities, which facilitate the generation of ROS and trigger lipid peroxidation-mediated ferroptosis. These findings highlight the innovative role of single-atom Ru in optimizing sonosensitizers for SDT-induced ferroptosis, demonstrating its potential for advancing cancer therapy.

Nanozymes-Mediated Lateral Flow Assays for the Detection of Pathogenic Microorganisms and Toxins: A Review from Synthesis to Application

In today's context, there is an increasing awareness among individuals regarding the importance of healthy and safe food consumption. Consequently, there is a growing demand for food products that are safeguarded against the detrimental effects of pathogens and harmful microbial metabolites. Actually, these organisms and their associated toxins pose a significant risk to food safety and are recognized as a critical threat to human health because of their capacity to induce foodborne infections and intoxications. Consequently, in order to address such challenges, it is imperative to enhance recognizing systems comprising bio/nanosensors for detections, which are trustworthy, quick, beneficial and economical. The advent of digital color imaging technology has led to the gradual establishment of lateral flow assays (LFAs) as one of the most significant sensors for point-of-care applications. Unlike colloidal gold nanoparticles (AuNPs), nanozymes offer enhanced color intensity through target-induced precise enrichment of nanozymes at the test line. Additionally, they amplify the color signal by facilitating the catalytic oxidation of colorless substrates into colored products. This dual functionality presents significant potential for the development of well-organized LFAs. In light of this, significant attempts are dedicated to the development of nanozyme-based LFAs. This review aims to outline recent advancements in the synthesis and design of nanozymes with varying compositions that exhibit distinct activities, as well as the structure and employment of nanozyme-based LFAs for the detection of pathogenic microorganisms and their associated toxins. Furthermore, the existing challenges and prospective development directions are outlined to assist readers in advancing the nanozyme-based LFAs performance.

Advances in the Treatment of Spinal Cord Injury with Nanozymes

Spinal cord injury (SCI) with increasing incidence can lead to severe disability. The pathological process involves complex mechanisms such as oxidative stress, inflammation, and neuron apoptosis. Current treatment strategies focusing on the relief of oxidative stress and inflammation have achieved good effects, while many problems and challenges remain such as the side effect and short half-life of the therapeutic agents. Nanozymes exhibiting good biocatalytic activities can sustainably scavenge free radicals, inhibit neuroinflammation, and protect the neurons. With high stability in physiological conditions and cost-effectiveness, the nanozymes provide a new strategy for SCI treatment. In this Review, we outline the advances of nanozymes and their enzyme-mimicking activities and highlight the progress in the intervention of SCI-adopting nanozymes. We also propose future directions and clinical translation for the nanozyme strategy against SCI.

Co-Delivery of Morphologically Switchable Au Nanowire and Hemoglobin-Resveratrol Nanoparticles in the Microneedle for Diabetic Wound Healing Therapy

Diabetic wounds are a common complication of diabetes and pose a significant threat to human health. High glucose concentration in the wound remains a major obstacle, necessitating effective strategies to achieve sustained glucose consumption for synergistic diabetic wound therapy. In this study, an Au-based nanomaterial is developed that can adjust its morphology in different therapeutic processes. The prepared Au nanowire (ANW) can be converted into Au nanospheres (AS) under ultrasonic conditions by adjusting the amount of polyethylene glycol (PEG) on its surface for convenient delivery. Intriguingly, AS is depolymerized into ANW again in the wound area, prolonging the retention time, and ensuring continuous consumption of glucose. After constructing the morphologically switchable Au nanowire, a polyvinyl alcohol (PVA) is applied it to microneedle and co-delivered it with hemoglobin (Hb)-resveratrol (RES) nanoparticles for synergistic diabetic wound therapy. In a streptozotocin (STZ)-induced diabetic mouse model, the microneedle degraded gradually, and the Hb-RES nanoparticles synergistically ameliorated hypoxia, scavenged ROS, and inhibited macrophage differentiation into pro-inflammatory M1 phenotypes. During this process, ANW continuously catalyzed glucose through its inherent glucose oxidase activity. Thus, this study provides novel insights into the long-term management of glucose concentration during synergistic diabetic wound healing.

Tuning Atomically Dispersed Metal Sites in Nanozymes for Sensing Applications

Nanozymes with atomically dispersed metal sites (ADzymes), especially single-atom nanozymes, have attracted widespread attention in recent years due to their unique advantages in mimicking the active sites of natural enzymes. These nanozymes not only maximize exposure of catalytic sites but also possess superior catalytic activity performance, achieving challenging catalytic reactions. These advantages position ADzymes as highly promising candidates in the field of sensing and biosensing. This review summarizes the classification and properties of ADzymes, systematically highlighting some typical regulation strategies involving central metal, coordination environment, etc., to achieve their catalytical activity, specificity, and multifunctionality. Then, we present the recent advances of ADzymes in different sensing fields, including colorimetry, fluorescence, electrochemistry, chemiluminescence, photoelectrochemistry, and electrochemiluminescence. Taking advantage of their unique catalytic performance, the resultant ADzymes show great potential in achieving the goal of sensitivity, selectivity and accuracy for the detection of various targets. Specifically, the underlying mechanisms in terms of signal amplification were discussed in detail. Finally, the current challenges and perspectives on the development of advanced ADzymes are discussed.

Covalent organic framework derived single-atom copper nanozymes for the detection of amyloid-β peptide and study of amyloidogenesis

Sensitive and accurate detection of the amyloid-β (Aβ) monomer is of fundamental significance for early diagnosis of Alzheimer's disease (AD). Herein, inspired by the specific Cu-Aβ monomer coordination, a cutting-edge colorimetric assay based on single-atom Cu anchored N-doped carbon nanospheres (Cu-NCNSs) was developed for Aβ monomer detection and an amyloidogenesis study. By directly pyrolyzing Cu2+-incorporated covalent organic frameworks (COFs), the resulting Cu-NCNSs with a high loading of Cu (8.04 wt %) exhibited outstanding peroxidase-like activity. The strong binding affinity of Aβ monomer to Cu-NCNSs effectively inhibited their catalytic activity, providing the basis for the colorimetric assay. The Cu-NCNSs-based sensor showed a detection limit of 1.182 nM for Aβ monomer, surpassing traditional techniques in terms of efficiency, accuracy and simplicity. Moreover, the system was successfully utilized for Aβ monomer detection in rat cerebrospinal fluid (CSF). Notably, the distinct inhibitory effects of monomeric and aggregated Aβ species on the catalytic activity of Cu-NCNSs were allowed for monitoring of the dynamic aggregation process of Aβ. Compared to thioflavin T (ThT), the most widely used amyloid dye, the detection system exhibited greater sensitivity towards toxic Aβ oligomers, which was crucial for early AD diagnosis and treatment. Our work not only sheds light on the rational design of highly active single-atom nanozymes from COFs but also expands the potential applications of nanozymes in early disease diagnosis.

Tailored Metal-Organic Framework-Based Nanozymes for Enhanced Enzyme-Like Catalysis

The global crisis of bacterial infections is exacerbated by the escalating threat of microbial antibiotic resistance. Nanozymes promise to provide ingenious solutions. Here, we reported a homogeneous catalytic structure of Pt nanoclusters with finely tuned metal-organic framework (ZIF-8) channel structures for the treatment of infected wounds. Catalytic site normalization showed that the active site of the Pt aggregates structure with fine-tuned pore modifications structure had a catalytic capacity of 14.903×105 min-1, which was 18.7 times higher than that of the Pt particles in monodisperse state in ZIF-8 (0.793×105 min-1). In situ tests revealed that the change from homocleavage to heterocleavage of hydrogen peroxide at the interface of the nanozyme was one of the key reasons for the improvement of nanozyme activity. Density-functional theory and kinetic simulations of the reaction interface jointly determine the role of the catalytic center and the substrate channel together. Metabolomics analysis showed that the developed nanozyme, working in conjunction with reactive oxygen species, could effectively block energy metabolic pathways within bacteria, leading to spontaneous apoptosis and bacterial rupture. This pioneering study elucidates new ideas for the regulation of artificial enzyme activity and provides new perspectives for the development of efficient antibiotic substitutes.

MnGA with multiple enzyme-like properties for acute wound healing by reducing oxidative stress and modulating signaling pathways

Nanozymes with specific catalytic activity inhibit inflammation and promote wound healing efficiently and safely. In this work, multifunctional manganese-based nanozymes (MnGA) with antioxidant properties were successfully constructed via a simple coordination reaction in which manganese chloride was used as the manganese source and gallic acid (GA) was used as the ligand solution. MnGA possesses both catalase-like (CAT-like) and superoxide dismutase-like (SOD-like) activities and a reactive nitrogen species (RNS) scavenging capacity, which enables it to efficiently inhibit the inflammatory response. Specifically, MnGA scavenges superoxide anions and produces H2O2 via SOD-like activity and then consumes H2O2 to convert it to nontoxic H2O and O2 via CAT-like activity, resulting in a cascade of catalytic reactions to scavenge reactive oxygen species (ROS). Moreover, the scavenging of RNS by MnGA can amplify the anti-inflammatory effect in combination with the scavenging of ROS. RNA sequencing of mouse skin tissue further revealed that MnGA significantly reduces inflammation by modulating the nuclear factor kappa-B (NF-κB), Toll-like receptor (TLR), and NOD-like receptor (NLR) signaling pathways and promotes skin regeneration. In summary, MnGA nanocatalysts possess excellent antioxidative and anti-inflammatory properties, highlighting their potential applications in wound healing and inflammation treatment.

Upgrading the Bioinspired Iron-Polyporphyrin Structures by Abiological Metals Toward New-Generation Reactive Oxygen Biocatalysts

Developing artificial enzymes based on organic molecules or polymers for reactive oxygen biocatalysis has broad applicability. Here, inspired by heme-based enzyme systems, we construct the abiological iron group metal-based polyporphyrin (Ru/Os-coordinated porphyrin-based biocatalyst, Ru/Os-PorBC) to serve as a new generation of efficient and versatile reactive oxygen species (ROS)-related biocatalyst. Due to the structural benefits, including excellent electron configuration, appropriate bandgap, and optimized adsorption and activation of reaction intermediates, Ru/Os-PorBC shows unparalleled ROS-production activities regarding maximum reaction rate and turnover numbers, which also demonstrates superior pH and temperature adaptability compared to natural enzymes. Impressively, the Os-PorBC manifests the most efficacious ROS-production capabilities, surpassing not only Ru/Fe-PorBC but also the existing state-of-the-art ROS-related biocatalyst. Our findings provide a pivotal direction for developing next-generation polyporphyrin-based biocatalysts, setting the stage for a new era of upgrading the artificial metalloenzymes by abiological metals.

Pt/Pd dual-modified porphyrin metal-organic frameworks for NIR-II photothermal-enhanced photodynamic/catalytic therapy

Photodynamic therapy (PDT) and catalytic therapy were promising treatment modes, but tumor hypoxia and poor catalytic activity severely limited their efficacies. Herein, using a porphyrin metal-organic framework (PCN-224) as nanocarrier, a platinum/palladium (Pt/Pd) dual-modified PCN-224 nanoprobe (PCN-224-Pt@Pd) with strong peroxidase (POD)/catalase (CAT)-like activities was developed, achieving photothermal-promoted PDT/catalytic therapy. Compared with single ultrasmall Pt modifying, CAT-like activity of Pt/Pd dual-modifying increased oxygen concentration from 6.24 to 9.35 mg/L, which improved singlet oxygen (1O2) yield from 63.8 % to 82.9 %. Moreover, POD-like activity of Pt/Pd dual-modifying significantly accelerated hydroxyl radicals (·OH) generation. Importantly, PCN-224-Pt@Pd possessed near-infrared II (NIR-II) photothermal effect with a high efficiency (55.6 %), which further promoted ·OH production. Under combined therapy of PCN-224-Pt@Pd, the cell survival rate greatly reduced to 5.8 %, and the tumors were cured, suggesting NIR-II photothermal-enhanced PDT/catalytic therapy.

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.

Transition-metal-based nanozymes for biosensing and catalytic tumor therapy

Nanozymes, as an emerging class of enzyme mimics, have attracted much attention due to their adjustable catalytic activity, low cost, easy modification, and good stability. Researchers have made great efforts in developing and applying high-performance nanozymes. Recently, transition-metal-based nanozymes have been designed and widely developed because they possess unique photoelectric properties and high enzyme-like catalytic activities. To highlight these achievements and help researchers to understand the research status of transition-metal-based nanozymes, the development of transition-metal-based nanozymes from material characteristics to biological applications is summarized. Herein, we focus on introducing six categories of transition-metal-based nanozymes and highlight their progress in biomarker sensing and catalytic therapy for tumors. We hope that this review can guide the further development of transition-metal-based nanozymes and promote their practical applications in cancer diagnosis and treatment.

Single-Atom Ce-Doped Metal Hydrides with High Phosphatase-like Activity Amplify Oxidative Stress-Induced Tumor Apoptosis

Phosphates within tumors function as key biomolecules, playing a significant role in sustaining the viability of tumors. To disturb the homeostasis of cancer cells, regulating phosphate within the organism proves to be an effective strategy. Herein, we report single-atom Ce-doped Pt hydrides (Ce/Pt-H) with high phosphatase-like activity for phosphate hydrolysis. The resultant Ce/Pt-H exhibits a 26.90- and 6.25-fold increase in phosphatase-like activity in comparison to Ce/Pt and Pt-H, respectively. Mechanism investigations elucidate that the Ce Lewis acid site facilitates the coordination with phosphate groups, while the surface hydrides enhance the electron density of Pt for promoting catalytic ability in H2O cleavage and subsequent nucleophilic attack of hydroxyl groups. Finally, by leveraging its phosphatase-like activity, Ce/Pt-H can effectively regulate intracellular phosphates to disrupt redox homeostasis and amplify oxidative stress within cancer cells, ultimately leading to tumor apoptosis. This work provides fresh insights into noble-metal-based phosphatase mimics for inducing tumor apoptosis.

A ruthenium single atom nanozyme-based antibiotic for the treatment of otitis media caused by Staphylococcus aureus

Staphylococcus aureus (S. aureus) infection is a primary cause of otitis media (OM), the most common disease for which children are prescribed antibiotics. However, the abuse of antibiotics has led to a global increase in antimicrobial resistance (AMR). Nanozymes, as promising alternatives to traditional antibiotics, are being extensively utilized to combat AMR. Here, we synthesize a series of single-atom nanozymes (metal-C3N4 SANzymes) by loading four metals (Ag, Fe, Cu, Ru) with antibacterial properties onto a crystalline g-C3N4. These metal-C3N4 display a rob-like morphology and well-dispersed metal atoms. Among them, Ru-C3N4 demonstrates the optimal peroxidase-like activity (285.3 U mg-1), comparable to that of horseradish peroxidase (267.7 U mg-1). In vitro antibacterial assays reveal that Ru-C3N4 significantly inhibits S. aureus growth compared with other metal-C3N4 even at a low concentration (0.06 mg mL-1). Notably, Ru-C3N4 acts as a narrow-spectrum nanoantibiotic with relative specificity against Gram-positive bacteria. Biofilms formed by S. aureus are easily degraded by Ru-C3N4 due to its high peroxidase-like activity. In vivo, Ru-C3N4 effectively eliminates S. aureus and relieves ear inflammation in OM mouse models. However, untreated OM mice eventually develop hearing impairment. Due to its low metal load, Ru-C3N4 does not exhibit significant toxicity to blood, liver, or kidney. In conclusion, this study presents a novel SANzyme-based antibiotic that can effectively eliminate S. aureus and treat S. aureus-induced OM.

Preparation and application of single-atom nanozymes in oncology: a review

Single-atom nanozymes (SAzymes) represent a cutting-edge advancement in nanomaterials, merging the high catalytic efficiency of natural enzymes with the benefits of atomic economy. Traditionally, natural enzymes exhibit high specificity and efficiency, but their stability are limited by environmental conditions and production costs. Here we show that SAzymes, with their large specific surface area and high atomic utilization, achieve superior catalytic activity. However, their high dispersibility poses stability challenges. Our review focuses on recent structural and preparative advancements aimed at enhancing the catalytic specificity and stability of SAzymes. Compared to previous nanozymes, SAzymes demonstrate significantly improved performance in biomedical applications, particularly in tumor medicine. This progress positions SAzymes as a promising tool for future cancer treatment strategies, integrating the robustness of inorganic materials with the specificity of biological systems. The development and application of SAzymes could revolutionize the field of biocatalysis, offering a stable, cost-effective alternative to natural enzymes.

Stimuli-responsive polymer-based nanosystems for cardiovascular disease theranostics

Stimulus-responsive polymers have found widespread use in biomedicine due to their ability to alter their own structure in response to various stimuli, including internal factors such as pH, reactive oxygen species (ROS), and enzymes, as well as external factors like light. In the context of atherosclerotic cardiovascular diseases (CVDs), stimulus-response polymers have been extensively employed for the preparation of smart nanocarriers that can deliver therapeutic and diagnostic drugs specifically to inflammatory lesions. Compared with traditional drug delivery systems, stimulus-responsive nanosystems offer higher sensitivity, greater versatility, wider applicability, and enhanced biosafety. Recent research has made significant contributions towards designing stimulus-responsive polymer nanosystems for CVDs diagnosis and treatment. This review summarizes recent advances in this field by classifying stimulus-responsive polymer nanocarriers according to different responsiveness types and describing numerous stimuli relevant to these materials. Additionally, we discuss various applications of stimulus-responsive polymer nanomaterials in CVDs theranostics. We hope that this review will provide valuable insights into optimizing the design of stimulus-response polymers for accelerating their clinical application in diagnosing and treating CVDs.

NIR-II Light-Driven Genetically Engineered Exosome Nanocatalysts for Efficient Phototherapy against Glioblastoma

Glioblastoma (GBM) poses a significant therapeutic challenge due to its invasive nature and limited drug penetration through the blood-brain barrier (BBB). In response, here we present an innovative biomimetic approach involving the development of genetically engineered exosome nanocatalysts (Mn@Bi2Se3@RGE-Exos) for efficient GBM therapy via improving the BBB penetration and enzyme-like catalytic activities. Interestingly, a photothermally activatable multiple enzyme-like reactivity is observed in such a nanosystem. Upon NIR-II light irradiation, Mn@Bi2Se3@RGE-Exos are capable of converting hydrogen peroxide into hydroxyl radicals, oxygen, and superoxide radicals, providing a peroxidase (POD), oxidase (OXD), and catalase (CAT)-like nanocatalytic cascade. This consequently leads to strong oxidative stresses to damage GBM cells. In vitro, in vivo, and proteomic analysis further reveal the potential of Mn@Bi2Se3@RGE-Exos for the disruption of cellular homeostasis, enhancement of immunological response, and the induction of cancer cell ferroptosis, showcasing a great promise in anticancer efficacy against GBM with a favorable biosafety profile. Overall, the success of this study provides a feasible strategy for future design and clinical study of stimuli-responsive nanocatalytic medicine, especially in the context of challenging brain cancers like GBM.

Precise Tuning of the D-Band Center of Dual-Atomic Enzymes for Catalytic Therapy

Single-atom nanozyme-based catalytic therapy is of great interest in the field of tumor catalytic therapy; however, their development suffers from the low affinity of nanozymes to the substrates (H2O2 or O2), leading to deficient catalytic activity in the tumor microenvironment. Herein, we report a new strategy for precisely tuning the d-band center of dual-atomic sites to enhance the affinity of metal atomic sites and substrates on a class of edge-rich N-doped porous carbon dual-atomic sites Fe-Mn (Fe1Mn1-NCe) for greatly boosting multiple-enzyme-like catalytic activities. The as-made Fe1Mn1-NCe achieved a much higher catalytic efficiency (Kcat/Km = 4.01 × 105 S-1·M-1) than Fe1-NCe (Kcat/Km = 2.41 × 104 S-1·M-1) with an outstanding stability of over 90% activity retention after 1 year, which is the best among the reported dual-atom nanozymes. Theoretical calculations reveal that the synergetic effect of Mn upshifts the d-band center of Fe from -1.113 to -0.564 eV and enhances the adsorption capacity for the substrate, thus accelerating the dissociation of H2O2 and weakening the O-O bond on O2. We further demonstrated that the superior enzyme-like catalytic activity of Fe1Mn1-NCe combined with photothermal therapy could effectively inhibit tumor growth in vivo, with an inhibition rate of up to 95.74%, which is the highest value among the dual-atom artificial enzyme therapies reported so far.