Nanozymes: Definition, Activity, and Mechanisms

CD44 and αV-integrins dual-targeting bimetallic nanozymes for lung adenocarcinoma therapy via NIR-enhanced ferroptosis/apoptosis

Combination therapy is a promising strategy for lung adenocarcinoma (LUAD), due to the advantages of overcoming drug resistance, side effects, and tumor heterogeneity. Herein, we report a novel dual-targeting bimetallic nanozyme (MH-iRGD) consisting of nanosized manganese ferrite (MF) after encapsulating with dopamine and methacrylic anhydride to modify hyaluronic acid, followed by integrin receptor targeting peptide (HS-PEG3400-iRGD) modification for LUAD targeted therapy. Our study confirmed that MH-iRGD combined with near-infrared irradiation (NIR) possessed dramatic photothermal effects and reactive oxygen species (ROS) production and GSH depletion abilities. Importantly, MH-iRGD possessed dual-targeting capacities for LUAD cells overexpressed CD44 and αV-integrin receptors owing to hyaluronic acid coating and iRGD modification. Inhibitors of CD44 and integrins could impair the uptake of MH-iRGD in LUAD cells. Moreover, MH-iRGD + NIR displayed excellent anti-LUAD effects as a result of the production of intracellular ROS, consumption of glutathione (GSH) and mitochondrial dysfunction. Mechanistically, NIR robustly strengthened MH-iRGD-induced ferroptosis and apoptosis by down-regulating SLC7A11, GPX4, Bcl-2 levels while up-regulating Bax level. Specifically, ferroptosis and apoptosis were increased while the LUAD progression was inhibited after intravenous injection of MH-iRGD + NIR in xenograft mouse models. Taken together, our results indicate that MH-iRGD + NIR serves as a promising targeted therapy for LUAD, which broadens the applications of highly active dual-targeting bimetallic nanozymes.

Advances in total antioxidant capacity detection based on nanozyme

Nanozymes, a class of nanomaterials mimicking natural enzymatic functions, have gained significant attention due to their exceptional biocatalytic properties and wide-ranging applications in biosensing. The total antioxidant capacity (TAC) can serve as a crucial parameter for assessing food quality, guiding dietary choices, and monitoring health conditions. In recent years, various nanomaterials with peroxidase (POD)-like and oxidase (OXD)-like activity have been widely used for TAC determination. This review discusses the enzyme-mimicking catalytic activities of nanozymes related to TAC determination, the construction principles of nanozyme-based TAC sensors and systematically classifies the application of nanozyme sensors in TAC determination. Furthermore, the potential opportunities and challenges in the development of nanozyme-based sensors are evaluated, aiming to provide valuable insights for researchers in related fields.

Colorimetric detection of cancer biomarker by using porous Mn-N-C single-atom nanozyme with peroxidase-like activity

Glutathione (GSH) is a critical antioxidant in biological systems involved in various cellular processes such as cell proliferation and apoptosis, and is considered as one of the cancer biomarkers. However, the conventional methods for detecting GSH levels often involve complex and time-consuming preparation and sophisticated equipment, posing challenges for rapid and straightforward analysis. Herein, we develop a colorimetric nanosensor using porous single-atom nanozymes (SAzymes), particularly those consisting of atomically dispersed metals on nitrogen-doped carbon supports (M-N-C), to monitor GSH quantitatively. The Mn-N-C SAzymes catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by hydrogen peroxide (H2O2), resulting in a measurable color change. The high porosity of the Mn-N-C SAzymes offers a large surface area accommodating a high density of accessible active sites for efficient catalysis. The addition of GSH in this system leads to a notable reduction in color intensity, offering an effective method for the quantitative measurement of GSH. The Mn-N-C SAzymes demonstrate high efficacy in the rapid colorimetric detection of GSH, with a low detection limit of 0.70 μM and a broad dynamic range of 0-40 μM. This method is further applied for a simple and rapid colorimetric analysis of the cancer biomarker in various biological samples, including tissues and serum. Demonstrating the potential for diagnostic applications, this approach offers a promising tool for clinical diagnostics, enabling reliable and convenient monitoring of GSH levels, which is crucial for assessing disease progression.

Synergistic microglial modulation by laminarin-based platinum nanozymes for potential intracerebral hemorrhage therapy

Abnormal microglial activation increases inflammation, causing significant brain damage after intracerebral hemorrhage (ICH). To aid recovery, treatments should regulate oxidative stress and inhibit the M1-like phenotype (pro-inflammation) of microglia. Recently, antioxidant nanozymes have emerged as tools for modulating microglial states, but detailed studies on their role in ICH treatment are limited. To address this, we developed an ultra-small (3-4 nm) laminarin-modified platinum nanozyme (Pt@LA) for the synergistic regulation of microglial polarization, offering a novel therapeutic strategy for ICH. Pt@LA effectively scavenges reactive oxygen species (ROS) through superoxide dismutase (SOD) and catalase (CAT)-like activities. Laminarin may inhibit the Dectin-1 receptor on microglia and its inflammatory pathway, Syk/NF-κB, reducing neuroinflammation. In vitro, Pt@LA decreased pro-inflammatory microglia and cytokine expression by inhibiting the Dectin-1/Syk/NF-κB and ROS-mediated NF-κB pathways. Furthermore, Pt@LA protected neurons, inhibited glial scar formation, and improved neurological function in ICH rats. Overall, this study presents Pt nanozymes based on naturally extracted laminarin and explores their application in alleviating oxidative stress and neuroinflammation after ICH, bridging nanozyme research and neuroscience.

Near-infrared light-responsive copper-cerium bimetallic oxide nanozyme with antibacterial and antioxidant abilities for periodontitis therapy

Periodontitis, a chronic inflammatory disease of the supporting tissue around teeth, is triggered by periodontal pathogens. Clinical treatments face the problem of bacterial resistance and most therapies focus on a single function, lacking the multifunctional treatment of antibacterial, antioxidant, anti-inflammatory, and osteogenic properties. In our study, we developed a copper-cerium bimetallic oxide (CuCeOx) nanozyme with near-infrared (NIR) light responsiveness for the periodontitis therapy. Under the excitation of 808 nm NIR light, CuCeOx displayed excellent photodynamic and photothermal activities, efficiently generating reactive oxygen species (ROS) and heat. After the treatment of the CuCeOx/NIR system, the inhibition rate of Porphyromonas gingivalis (P. gingivalis), the main periodontitis pathogen, reached 98.69 ± 0.23 % in vitro. Without the NIR light irradiation, CuCeOx, acting as a nanozyme, exhibited enzyme-like activity in scavenging ROS, effectively alleviating the cellular oxidative stress. Furthermore, CuCeOx significantly mitigated the cellular inflammatory response induced by lipopolysaccharide (LPS) and promoted osteogenesis under the oxidative stress condition. Notably, the CuCeOx exhibited excellent blood compatibility (hemolysis < 5 %). The efficacy of the CuCeOx/NIR system in vivo was also investigated. H&E staining results demonstrated a significant reduction in periodontal tissue inflammation following treatment. Micro-CT analysis revealed that CuCeOx effectively inhibited the alveolar bone loss. Additionally, we found CuCeOx regulated the Nrf2/HO-1 signaling pathway both in vitro and in vivo. In conclusion, the multifunctional nanomaterial CuCeOx provides a promising strategy for the treatment of periodontitis.

Flip-PAD integrating laser-scribed platinum-nanozyme for rapid smartphone-based colorimetric determination of ascorbic acid

BACKGROUND

The development of portable easy-to-use devices to selectively determine antioxidants still represents an open issue; antioxidants, in fact, often coexist and have similar redox reactivity. In this framework, ensuring selective colorimetric reactivity in Paper-based Analytical Devices (PAD) for a single antioxidant compound is a challenge, and the selective determination still requires time-consuming and cumbersome methods.

RESULTS

A disposable paper-based device (Flip-PAD) for the rapid and selective colorimetric determination of ascorbic acid (AA) is proposed. The Flip-PAD is equipped with a platinum nanostructured (L-nPt) catalytic paper realized using a CO2 laser, able to oxidize 3,3',5,5'-tetramethylbenzidine (TMB); the selective inhibition of the reaction by AA gives the analytical signal. The L-nPt paper in the Flip-PAD is coupled with fiberglass loaded with TMB, and assembled in an array format to allow the simultaneous analysis of 5 samples in 1 min; a smartphone camera is used for the RGB signal acquisition. The L-nPt CO2-laser-based synthesis was carefully optimized to maximize the nanozyme (oxidase-mimicking) activity; TMB-catalytic conversion and AA-mediated inhibition were carefully studied via colorimetric, spectroscopic and microscopical analysis. The catalytic conversion of uncolored-TMB in blue-colored TMBox occurs in 1 min, with no additional reagent needed; the AA-induced TMB-catalytic conversion inhibition results in a dye conversion 'switch-off' employed as analytical signal.

SIGNIFICANCE

AA dose-response signal resulted linear from 31 to 250 mg kg-1 (R2 = 0.992), showing a LOD of 6 mg kg-1; analytical performance resulted constant over 6 weeks (RSD = 4 %). The Flip-PAD exploitability was proved for the AA determination in different foods and pharmaceutical samples, returning accurate (recoveries 92-114 %; relative error -11/+4 %) and reproducible (RSD ≤10 %; n = 3) data. The proposed laser-based approach opens new paths for PADs and nanostructured systems development.

Fabrication of fluorescence sensor array for discrimination subtypes of aminoglycosides leveraging MOF-based inhibition reactions and thiol-response metal nanoclusters

Detection and discrimination aminoglycoside (AG) subtypes are crucial, which remains a formidable challenge. In this study, a sensor array for differentiating of AGs was developed. This was achieved by integrating the inhibitory effect of AGs on the acetylcholinesterase (AChE)-like activities of Al3+ decorated MOF-808 (MOF-808-Al) and the thiol-response fluorescence of metal nanoclusters (NCs). MOF-808-Al exhibited AChE-like activities, which catalyzed the decomposition of AChE into thiocholine, ascribed to the synergistic effect of metal-OH and Lewis acid sites. Thiocholine quenched the green fluorescence of Au NCs by forming Au-S bonds. In contrast, the blue-emissive Cu NCs showed high resistance to thiocholine. AGs inhibited the AChE-like activities of MOF-808-Al through forming stronger interactions with metal and Lewis acid sites compared to acetylthiocholine. By analyzing the fluorescence changes of green- and blue-emissive metal NCs, a sensor array was constructed, and five subtypes of AGs were quantitatively detected and discriminated, with a limit of detection and limit of quantitation of 11.2 μM and 12.9 μM, respectively. The discrimination of mixed AGs in both buffer solutions and practical samples was also successfully achieved, indicating the great potential for practical applications.

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.

Engineered Prussian Blue-Curcumin Nanozyme with RONS Scavenging Properties for Augmented Reversible Treatment of Cardiac Hypertrophy

Pathological cardiac hypertrophy, often triggered by the excessive production and accumulation of reactive oxygen and nitrogen species (RONS), may ultimately lead to heart failure. The treatment of myocardial hypertrophy often involves antioxidant stress therapy. In this study, by coordinating curcumin with ferric ions during the synthesis of Prussian blue nanoparticles, a Prussian blue-curcumin (PB-Cur) nanozyme is successfully engineered with exceptional reactive oxygen and nitrogen species (RONS) elimination capabilities. Following PVP modification, the PB-Cur nanozyme exhibited favorable biocompatibility and stability in aqueous solutions. Furthermore, the PB-Cur nanozyme shows remarkable reversible treatment efficacy against myocardial hypertrophy in both in vitro and in vivo models. After one week of treatment, the PB-Cur group in the transverse aortic constriction (TAC)-induced cardiac hypertrophy models displayed a notable decrease in myocardial hypertrophy and fibrosis. Echocardiographic findings also revealed a substantial improvement in cardiac function among TAC mice following PB-Cur administration. Mechanistically, through reactive oxygen species (ROS) elimination, the PB-Cur effectively downregulated oxidative stress-related pathways, including MAPK and PI3K-Akt, which hold promise for treating oxidative stress-related cardiac diseases.

Selenium as a brightening agent for peroxidase-like activity regulation of MXene@CeO2 sensing platform

Selenium is a nutritionally essential trace element for human health, but efficient or excessive intake both causes physiological diseases. Here, we propose that selenium as a brightening agent significantly increase the peroxidase (POD)-like activity of MXene@CeO2, which CeO2 nanoparticles in-situ grow on MXene as the sensing platform. Based on the selenium-stimulated POD-like activity of MXene@CeO2, a simple, low-cost, and reliable colorimetric method is constructed for quantitative analysis of selenium. The great advantage of MXene@CeO2 platform selecting selenium as brightening agent exhibits good selectivity for other 23 interfering ions, allowing the discrimination of selenium in practical samples rapidly and precisely even at 3.5 nM. Moreover, MXene@CeO2 platform selectively catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) instead of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium (ABTS) under the same condition. This study not only offers a utility sensing platform for quick detection of selenium but also opens an avenue for the rational design of element sensors for point-of-care application.

Multiscale metal-based nanocomposites for bone and joint disease therapies

Bone and joint diseases are debilitating conditions that can result in significant functional impairment or even permanent disability. Multiscale metal-based nanocomposites, which integrate hierarchical structures ranging from the nanoscale to the macroscale, have emerged as a promising solution to this challenge. These materials combine the unique properties of metal-based nanoparticles (MNPs), such as enzyme-like activities, stimuli responsiveness, and photothermal conversion, with advanced manufacturing techniques, such as 3D printing and biohybrid systems. The integration of MNPs within polymer or ceramic matrices offers a degree of control over the mechanical strength, antimicrobial efficacy, and the manner of drug delivery, whilst concomitantly promoting the processes of osteogenesis and chondrogenesis. This review highlights breakthroughs in stimulus-responsive MNPs (e.g., photo-, magnetically-, or pH-activated systems) for on-demand therapy and their integration with biocomposite hybrids containing cells or extracellular vesicles to mimic the native tissue microenvironment. The applications of these composites are extensive, ranging from bone defects, infections, tumors, to degenerative joint diseases. The review emphasizes the enhanced load-bearing capacity, bioactivity, and tissue integration that can be achieved through hierarchical designs. Notwithstanding the potential of these applications, significant barriers to progress persist, including challenges related to long-term biocompatibility, regulatory hurdles, and scalable manufacturing. Finally, we propose future directions, including machine learning-guided design and patient-specific biomanufacturing to accelerate clinical translation. Multiscale metal-based nanocomposites, which bridge nanoscale innovations with macroscale functionality, are a revolutionary force in the field of biomedical engineering, providing personalized regenerative solutions for bone and joint diseases.

A Bimetallic Nanozyme Synergistic Effect-Driven Enzyme Cascade Nanoreactor for Instant Immunoassay

This study presents a colorimetric sensor for cancer screening utilizing the bifunctional enzyme activity of NiCo Prussian blue analogue (PBA), a PBA material. By introducing oxygen vacancies and employing a dual-metal doping strategy, NiCo PBA overcomes the limitations in catalytic activity observed in single-metal-doped materials (such as Ni PBA and Co PBA), significantly enhancing both peroxidase-like (POD) and catalase-like (CAT) activities. Compared to single-metal-doped Ni PBA and Co PBA, NiCo PBA exhibited a 30.08-fold increase in POD activity and a 4.83-fold increase in CAT activity, demonstrating higher sensitivity in carcinoembryonic antigen (CEA) detection. By integrating NiCo PBA with a cascade catalytic reaction principle, we developed a highly efficient and sensitive CEA detection method. NiCo PBA was utilized as a catalytic material in this method. Under the action of glucose oxidase, the decomposition of hydrogen peroxide was catalyzed by NiCo PBA, and oxygen was generated. Furthermore, a blue flocculent substance was produced when NiCo PBA was reacted with a chromogenic substrate. Through mutual verification by these two methods, the quantitative determination of CEA in serum samples was achieved. The experimental results demonstrated that the POD-like activity detection range was 0.2-50 ng mL-1, with a limit of detection (LOD) of 0.061 ng mL-1, while the CAT-like activity detection range was 0.1-20 ng mL-1, with an LOD of 0.028 ng mL-1. The sensitivity of this method was substantially increased compared to monometallic materials. Furthermore, this strategy possesses good scalability and can be adapted for the detection of various analytes by replacing different recognition units, providing an efficient detection platform for early cancer screening.

Bioinspired rational design of nanozymes

Nanozymes, an emerging class of artificial enzymes, have attracted increasing attention for their potential in environmental monitoring, industrial catalysis, food safety, and biomedicine. To date, more than 1500 nanomaterials have been identified with enzyme-like activities, some demonstrating catalytic performances that match or even exceed those of natural enzymes. Despite this progress, key challenges remain, including poorly understood catalytic mechanisms, ambiguous structure-activity relationships, and a heavy dependence on nonspecific surface sites, all of which limit the efficiency, selectivity, and broader application of nanozymes. To address these limitations, researchers are turning to nature for inspiration, seeking to reconstruct enzyme active centers at the atomic scale and establish innovative design principles. This review examines the catalytic mechanisms and structural characteristics of natural enzymes, integrating machine learning approaches to investigate nanozyme kinetics, transition state stabilization, electron/proton transfer, and cooperative effects. It highlights bioinspired strategies such as three-dimensional structure design, cofactor incorporation, and artificial organelle systems. Furthermore, the review explores rational nanozyme design using activity descriptors and predictive modeling. Finally, it outlines the transformative potential of artificial intelligence and multiscale simulations in optimizing nanozyme performance, offering a theoretical foundation for the development of next-generation intelligent nanozymes.

Synergistic healing of diabetic wounds through photothermal and peroxidase-like activity of heterogeneous Bi2S3/Au nanoparticles

Bacterial resistance and biofilm formation around diabetic wounds are major challenges that make the wounds difficult to heal. It is crucial for diabetic wound healing to improve the microenvironment around the wounds. In this study, a novel strategy for diabetic wound healing is developed by combining the peroxidase (POD)-like enzyme activity and photothermal therapy (PTT) to protect against bacterial infections around the wounds. Heterogeneous bismuth sulfide/gold nanoparticles (Bi2S3/Au NPs) are synthesized through a two-step wet chemical route. Results show that Bi2S3/Au nanozymes display high POD-like enzyme activity and can effectively convert H2O2 into ˙OH. The antibacterial rate against S. aureus and E. coli bacteria is 99.8 ± 0.03% and 99.9 ± 0.01%, respectively, in the presence of H2O2 under near-infrared light (NIR) irradiation. Animal experiments on infected diabetic wounds demonstrate that the synergistic actions of the Bi2S3/Au NPs significantly inhibit the formation of biofilms caused by bacteria, and promote the deposition of collagen and the formation of epithelial and dermal tissue. This study provides a promising solution for innovative therapy of refractory diabetic wounds, which is of great significance for reducing the abuse of antibiotics and the production of drug-resistant bacteria.

Unusual oxidase-mimetic catalytic performance surpassing peroxidase in amorphous CoOx: underlying mechanism and toward a novel H2O2-related detection paradigm

Different from crystalline cobalt oxides (Co3O4 and CoO) and most reported nanozymes, amorphous CoOx was found to exhibit better oxidase-like catalytic performance than the peroxidase one. Mechanistic investigations revealed that the introduction of H2O2 could decompose CoOx into inactive Co2+ under acidic conditions, leading to the loss of catalytic activity. With the unusual phenomenon, a proof-of-concept "turn-off" cascade system was fabricated to detect glucose colorimetrically via combining CoOx with glucose oxidase.

Dual Functions of Fluorescence and Peroxidase Mimics for Hemin@NH2-UiO-66 and Ratiometric Fluorescence Sensing to l-Cysteine

The bifunctions of fluorescence activity and peroxidase mimics were well-integrated by a hemin chloride-modified Zr-based metal-organic framework (Hemin@NH2-UiO-66), which can catalyze the oxidation of o-phenylenediamine (OPD) to generate 2,3-diaminophenazine (DAP), presenting typical peroxidase mimic properties. The influence of the introduction of hemin chloride upon the enhanced peroxidase mimic activity was clarified, and the nanozyme catalytic parameters were optimized. Interestingly, the oxidized product of DAP presents strong fluorescence emission at 564 nm; combining it with the intrinsic fluorescence emission of NH2-UiO-66 at 452 nm, a dual-emission system could be built up by the resulting Hemin@NH2-UiO-66 in the presence of definite OPD and H2O2. Moreover, the fluorescence quenching effect (564 nm) was observed by adding l-cysteine (l-Cys); based on that, a straight-line dependence of the fluorescence intensity ratio (I452/I564) upon the concentrations of l-Cys was established. The detection limit was 0.21 μmol, and the analytical selectivity for l-Cys was also demonstrated. The work highlights the idea of combining the intrinsic fluorescence property and nanozyme catalytic activity in a functional MOF, and its special usability is found in the ratiometric fluorescence sensing analyses.

Double crystallization-driven copper-2-methylimidazole nanoflowers: Stabilizing glucose oxidase and activating nanozyme functions for tandem catalysis

Based on the structural characteristics of metal-organic framework (MOF) synthesis, we designed a double-crystallized copper-2-methylimidazole nanoflower (DCu NF) platform in which glucose oxidase (GOx) was incorporated to form an enzyme-nanozyme hybrid for glucose sensing. The D-Cu@GOx NF system mimics a GOx-horseradish peroxidase-like multi-enzyme cascade, benefiting from synergistic oxidation capabilities. Double crystallization of Cu nanoflowers (Cu-NFs) was crucial for inducing nanozyme activity by creating a unique Fenton-like reaction site, enhancing both cascade activity and enzyme stability. The system was constructed using a self-assembly method, integrating Cu-NF synthesis with in situ GOx immobilization. The double crystallization of Cu-NFs expanded the surface area, forming D-Cu@GOx NFs, which significantly enhanced cascade activity and enzyme stability. The system demonstrated excellent glucose detection performance, maintaining 88 % of enzyme activity after 30 days at room temperature, with temperature resistance up to 60 °C and pH stability between 3 and 8. The enhanced oxidation from the Cu metal Fenton-like reaction site enabled sensitive glucose detection over a wide linear range (0-50 μM), with a limit of detection of 1.25 μM. The system also showed high reproducibility, with a relative standard deviation of <5 % across five replicate measurements. Furthermore, it successfully detected human blood glucose in real samples, with results comparable to standard clinical methods. This report presents Cu NF synthesis with an integrated GOx approach, demonstrating cost-effectiveness through enhanced stability and sensitivity that reduces enzyme usage and enables rapid, accurate glucose biosensing. The D-Cu@GOx NFs, a hybrid enzyme-nanozyme complex, offer improved sensitivity and stability for glucose detection in serum. By enhancing enzyme stability, the system eliminates the need for dual enzymes, reducing costs and improving efficiency, while maintaining cost-effectiveness for industrial and diagnostic applications.

Zirconium-doped iron oxide nanoparticles for enhanced peroxidase-like activity

Fe3O4 nanoparticles (NPs) have emerged as pioneering nanozymes with applications in clinical diagnosis, environmental protection and biosensing. However, it is currently limited by insufficient catalytic activity due to poor electron transfer. In this study, we synthesized electron-rich-Zr-doped defect-rich Fe3O4 NPs (Zr3Fe3O4) using a one-pot solvothermal method. Compared with intrinsic Fe3O4 NPs, the resultant Zr3Fe3O4 NPs exhibit enhanced peroxidase (POD)-like activity attributed to the presence of active centers of Zr-O-Fe bridges and adsorption sites of asymmetric oxygen vacancies (OVs) Zr-OVs-Fe. The Zr-O-Fe bridges facilitate electron transfer from Zr to Fe, promoting the regeneration of surface Fe2+ in Fe3O4 NPs. Furthermore, the rich Zr-OVs-Fe significantly enhances the adsorption and electron transfer between catalyst and substrates, thereby regulating the generation pathway of 1O2. Leveraging the remarkable POD-like activity of Zr3Fe3O4 NPs, we developed a tandem enzyme-catalyzed reaction for colorimetric detection of glucose. This strategy of constructing active centers by atom doping provides valuable guidance for the development of more efficient Fenton-like catalytic systems with broad applications on a large scale.

Nanozymes or Spirulina Platensis: Enhancing Sheep Thermo-Tolerance Through Physio-Metabolic, Immune, and Antioxidant Pathways

This study evaluated the potential of supplementing sheep diets with cobalt (CoNPs), iron (FeNPs) nanoparticles, or Spirulina platensis (SP) to tackle the adverse impacts of heat stress by assessing growth performance, oxidative status, metabolic pathways, immune parameters, gene expression, and hormone levels in sheep exposed to hot environmental conditions. A total of 32 Rahmani male lambs were randomly divided into four equal groups (n = 8). The CON group was fed the control diet or supplemented with 2 mg/kg of CoNPs (CoNPs group), 50 mg/kg of FeNPs (FeNPs group), or 1 g of SP/kg (SP group) diet for 3 months. The average size of nanozymes CoNPs and FeNPs were 41 and 44 nm, respectively. The temperature humidity index (THI) was 81.99 overall the study period. All nanozyme or SP treatments significantly (P < 0.05) enhanced growth performance, including final and average body weight, and dry matter intake. Nanozyme treatments also achieved the best results regarding hematocrit (P < 0.01) and platelets (P < 0.01). All supplemented groups exhibited lower WBC and lymphocyte counts, and higher globulin levels in comparison to stressed sheep. Total protein levels were significantly (P < 0.001) elevated in the FeNPs and SP groups compared to the remaining groups. Rams fed CoNPs or SP had notably (P < 0.001) higher TC and TG levels, while the FeNPs group showed the lowest TC levels (P < 0.05), as well as the lowest VLDL and LDL levels (P < 0.05). The levels of blood immune markers, specifically lysozyme, IgG, and IgM, were significantly (P < 0.05) elevated in all supplemented groups in comparison to the untreated group. Furthermore, rams receiving FeNPs demonstrated higher (P < 0.05) values for TAC, CAT, SOD, and GPX, and lower MDA levels than the other groups. Additionally, the supplemented group exhibited greater (P < 0.05) leptin and testosterone levels than the stressed group. Further, serum concentrations of zinc, selenium, and iron were significantly (P < 0.05) greater in the nano-feed additives and SP groups compared to the HS group. Dietary supplementation with nanozymes or SP notably (P < 0.05) upregulated GPX1 and HSP70 expression and downregulated TNF-alpha mRNA levels (P < 0.05). In summary, dietary supplementation with nanozymes or microalgae robustly bolstered sheep's immune-antioxidant capacity, improved growth performance, and promoted health under heat stress conditions relevant to global warming.

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.

Fe3O4@Ag@Pt nanoparticles with multienzyme like activity for total antioxidant capacity assay

A simple and reliable total antioxidant capacity (TAC) assay is essential for food safety evaluation and human health monitoring. Herein, a trimetallic nanozyme (Fe3O4@Ag@Pt) was synthesized and exhibited OXD-, POD- and SOD-like activities, which could generate a synergistic catalytic system. Fe3O4@Ag@Pt can catalyze oxygen to produce various reactive oxygen intermediates, and the endogenous product H2O2 could be captured and further dissociated efficiently into •OH, due to its strong substrate binding affinity. Since antioxidants can compete with TMB and lead to an antioxidant concentration-dependent color change, a colormetric sensing platform was constructed with a detection limit of 1.97 μM, 5.06 μM, and 8.99 μM for GSH, AA and Trolox, respectively. The proposed Fe3O4@Ag@Pt based assay was suitably employed to quantify TAC in fruit samples, beverages and cells with the aid of spike recovery and reference method validation, which hold vast promise as an analytical platform for food safety and biomedical diagnosis.

Tetrapyrrole organics-modified cerium nanozyme with enhanced oxidase-like activity for integration of detection and degradation of antibiotic

The massive accumulation of antibiotics accelerates the emergence of antibiotic resistance causing inevitable risks to human and ecosystem. To realize the integration of detection and degradation of antibiotics, it is urgent for exploring novel nanozyme materials with the excellent catalytic activity. Integrating nanozyme with tetrapyrrole-based organics is an effective strategy to enhance the catalytic activity. Herein, a series of tetrapyrrole organics with different energy levels are severally modified on cerium oxysulfate clusters (Ce-clusters) surface to fabricate nanozyme. The mechanism of nanozyme with enhanced catalytic activity was importantly explored by the energy band matching principle. At present, there are no studies that systematically research the enhancement mechanism of tetrapyrrole-based organics with different energy levels on the catalytic activity of nanozyme. Especially, Ce-clusters modified with meso-tetra (4-carboxyphenyl) porphyrin (TCPP) has the best energy band matching, resulting in the highest catalytic activity. Remarkably, the resultant nanozyme exhibits rapid and sensitive colorimetric response to tetracycline within the range of 0-0.3 mg mL-1, and the limit of detection was determined to 0.027 mg mL-1. It also possesses favorable degradation performance to tetracycline under natural light with pH adaptability, strong inorganic ions and organic matter interference tolerance, high reusability, and strong stability. Its degradation efficiency is up to 97.6 % in 60 min, much higher than other types degradation strategies. This study provides a useful principle for designing highly activity nanozyme and a powerful tool to simultaneous detection and degradation of antibiotic, holding great promise for practical application.

Nanozymes in biomedicine: Unraveling trends, research foci, and future trajectories via bibliometric insights (from 2007 to 2024)

Nanozymes, a new generation of artificial enzymes, have attracted significant attention in biomedical applications due to their multifunctional properties, multi-enzyme mimicking abilities, cost-effectiveness, and high stability. Leveraging these diverse catalytic activities, an increasing number of nanozyme-based therapeutic strategies have been developed for the treatment of various diseases. Despite substantial research efforts, a significant gap remains in comprehensive studies examining the progression, key areas, current trends, and future directions in this field. This study provides a comprehensive overview of nanozyme applications in biomedical research over the past 17 years, utilizing data from the Web of Science Core Collection, covering the period from January 1, 2007, to October 8, 2024. Advanced bibliometric and visualization tools were employed to facilitate a comprehensive analysis. The results highlight China's dominant role in this field, accounting for 76.83 % of total publications, significantly influencing the evolution of research in this area. Key contributions were made by institutions such as the Chinese Academy of Sciences, the University of Chinese Academy of Sciences, and the University of Science and Technology of China, with Qu Xiaogang as the leading author. The journal ACS Applied Materials & Interfaces has become the most prolific publisher in this field. Keyword analysis indicates that since 2022, research hotspots in this field have increasingly focused on areas such as photothermal therapy, chemodynamic therapy, and ferroptosis. Challenges such as obstacles to clinical translation, limitations in recyclability, and insufficient targeting ability were addressed. The potential applications of emerging interdisciplinary technologies, such as artificial intelligence, machine learning, and organoids, in advancing nanozyme development were explored. This study offers a data-driven roadmap for researchers to navigate the evolving landscape of nanozyme innovation, emphasizing interdisciplinary collaboration in impactful biomedical applications.

Excellent Laccase Mimic Activity of Cu-Melamine and Its Applications in the Degradation of Congo Red

Copper-based nanozyme has shown the superior in the oxidase-like activities due to its electron transfer ability between the Cu(I) and Cu(II) sites during the catalytic reactions. Herein, a Cu(I)-MOF (Cu-Mel) was readily synthesized by a traditional hydrothermal process using the precursors of Cu+ and melamine, which was then used in the laccase-like catalytic reactions for the first time. Some means, such as X-ray diffraction (XRD), Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS), were employed to character the microstructure of the Cu-Mel. The catalytic oxidation of the 4-aminoantipyrine (4-AP) and 2,4-dichlorophenol (2,4-DP) was adopted to evaluate the laccase-like catalytic ability of the resulting Cu-Mel. The catalytic conditions including the temperatures, the presence of alcohols, and the ionic concentrations were varied to optimize the laccase-like activities, based on that, the highest laccase-like catalytic activity is presented with a higher maximum reaction rate (Vmax). The good storage stability is also presented by the Cu-Mel. The Cu-Mel was utilized in the degradation of Congo red, showing a good degradation efficiency. These findings facilitate the development of the laccase mimics and serve as a foundation for the design and applications of Cu-MOFs in the nanozyme realm.

Chimeric Nanozyme Bacterial Outer Membrane Vesicles Reprograming Tumor Microenvironment for Safe and Efficient Anticancer Therapy

This study presents an innovative approach utilizing a biocompatible shell to shield bacterial outer membrane vesicles (OMVs) and incorporate Fe ions and ultrasmall Au nanoparticles to develop a combined tumor therapeutic strategy. These chimeric nanozyme shells effectively reduce the toxicity of OMVs during circulation and promote their accumulation in tumor tissues. In the tumor microenvironment, Au nanoparticles act as nanozymes, catalyzing glucose consumption and elevating H₂O₂ levels. The increased H₂O₂ subsequently reacts with the released Fe ions to induce immunogenic tumor cell death through iron-mediated chemodynamic mechanisms. Simultaneously, the release of tumor-associated antigens and OMVs synergistically stimulates the immune response. This cascade of nanozyme-catalyzed reactions, chemodynamic effects, and immune activation results in efficient tumor inhibition.

Amorphous RuO2 Nanozymes with an Excellent Catalytic Efficiency Superior to Natural Peroxidases

Developing efficient peroxidase-like nanozymes to surpass natural enzymes remains a significant challenge. Herein, an amorphous RuO2 nanozyme with peroxidase-like activity is synthesized for activating H2O2 with a specific activity of 1492.52 U mg-1, outperforming the crystalline RuO2 nanozymes by a factor of 22 and far superior to natural peroxidases. Amorphous RuO2 nanozymes with long-range disordered atomic arrangements can effectively elongate the O─O bonds in H2O2. Abundant oxygen vacancies in amorphous RuO2 nanozymes lead to an upshift of the d-band center, enhancing the exceptional adsorption strength of H2O2, which improve the electron transfer efficiency and ensure superior peroxidase-like activity. Accordingly, a nanozyme-linked immunosorbent assay is developed for the precise and sensitive detection of prostate-specific antigens with a detection limit as low as 0.52 pg mL-1. This study introduces a simple approach for developing high-performance peroxidase-like nanozymes to improve the analytical performances of prostate-specific antigens in clinical diagnostics.

Metal-Organic Frameworks: Unlocking New Frontiers in Cardiovascular Diagnosis and Therapy

Cardiovascular disease (CVD) is one of the most critical diseases which is the predominant cause of death in the world. Early screening and diagnosis of the disease and effective treatment after diagnosis play an important role in the patient's recovery. Metal-organic frameworks (MOFs), a kind of hybrid ordered micro or meso-porous materials, constructed by metal nodes or clusters with organic ligands, due to their special features like high porosity and specific surface area, open metal sites, or ligand tunability, are widely used in various areas including gas storage, catalysis, sensors, biomedicine. Recently, advances in MOFs are bringing new developments and opportunities for the healthcare industry including the theranostic of CVD. In this review, the applications of MOFs are illustrated in the diagnosis and therapy of CVD, including biomarker detection, imaging, drug delivery systems, therapeutic gas delivery platforms, and nanomedicine. Also, the toxicity and biocompatibility of MOFs are discussed. By providing a comprehensive summary of the role played by MOFs in the diagnosis and treatment of CVDs, it is hoped to promote the future applications of MOFs in disease theranostics, especially in CVDs.

Mechanism of pesticide thiram reversibly inhibiting of Pt single-atom peroxidase-mimicking nanozyme and its application in colorimetric sensing thiram

Nanozymes hold great promise in catalysis-based sensing. However, little attention has been paid to inhibition mechanism of nanozymes, which impeded their sensing application. Herein, we report a sensitive colorimetric sensing platform for detecting pesticide tetramethylthiuram disulfide (thiram) based on its inhibition of Pt single-atom nanozymes (SAN)-based peroxidase (POD)-like activity. Thiram containing dimethyl dithiocarbamate (DMDTC) unit capable of inhibiting POD-like activity of Pt SAN because the disulfide bond was cleaved to form DMDTC, which further formed Pt-S bond with Pt SAN. The enzyme-substrate interaction and the substrate's inhibitory mechanism were investigated. Thiram can inhibit the POD-like activity of Pt SAN reversibly with mixed inhibition (competitive inhibition and non-competitive inhibition) and uncompetitive inhibition with the inhibition constants (Ki) of 9.079 and 0.382 mM, respectively. Finally, based on the inhibition mechanism, a colorimetric sensor was constructed, exhibiting two linear parts of 0.025-1 μM and 1-15 μM with a detection limit of 9.24 nM thiram. The as-proposed method can be applied to detect thiram in real samples with good reproducibility. This work not only lays the foundation for study on the inhibition mechanism between other nanozymes and inhibitors, but also provides a new method for detecting trace thiram in environmental samples.

Dual Activities of Flower-Like Gold-Iron Oxide Nanozyme for Peroxidase-Mimicking and Glucose Detection

Nanozymes, constituting of inorganic nanomaterials, are the sustainable and cost-effective alternatives of the naturally abundant enzymes. For more than a decade, nanozymes have shown astonishingly enhanced enzymatic activity as compared to its naturally occurring counterpart and emerged as a potential platform in biomedical science. The current study reports a novel flower shaped gold-iron oxide nanocomposite prepared via a facile and green solution phase redox mediated synthesis. The precursor gold salt conversion to nanometallic Au(0) is mediated by iron metal powder, which acts both as reductant and metal source in the resultant gold nanoparticle decorated iron oxide nanocomposite. Calcination of the synthesized nanocomposites leads to morphological evolution into unique flower shape with improved homogeneity between gold and iron components along with metal surface exposure. The gold-iron oxide nanocomposites have been utilized first time for peroxidase mimicking study and exhibit enhanced catalytic activity at 25 °C with low Michaelis-Menten constant (Km) and higher maximum reaction velocity (Vmax) as compared to the natural enzyme Horseradish peroxidase (HRP). In addition, combined assembly of this nanozyme with natural enzyme glucose oxidase also serves a potential platform for the visible colorimetric detection and quantification of glucose with limit of detection (LOD) of 15 μM.

Artificial intelligence driven platform for rapid catalytic performance assessment of nanozymes

Traditional methods for synthesizing nanozymes are often time-consuming and complex, hindering efficiency. Artificial intelligence (AI) has the potential to simplify these processes, but there are very few dedicated nanozyme databases available, limiting the resources for research and application. To address this gap, we developed AI-ZYMES, a comprehensive nanozyme database featuring 1,085 entries and 400 types of nanozymes. The platform incorporates several key innovations that distinguish it from existing databases: Firstly, standardized Data Curation: AI-ZYMES resolves inconsistencies in catalytic metrics (e.g., Km, Vmax), morphologies, and dispersion systems, enabling reliable cross-study comparisons, something that existing resources like DiZyme and nanozymes.net lack.Secondly, dual AI Framework: A gradient-boosting regressor predicts kinetic constants (Km, Vmax, Kcat) with an R2 up to 0.85, while an AdaBoost classifier identifies enzyme-mimicking activities based solely on nanozyme names, surpassing traditional random forest models in predictive accuracy.Lastly, ChatGPT-based Synthesis Assistant: The platform includes an AI-driven assistant for literature extraction (67.55% accuracy) and synthesis pathway generation via semantic analysis (90% accuracy). This reduces manual effort and minimizes errors in large language model outputs, ensuring high-quality results.These innovations make AI-ZYMES a valuable tool for accelerating nanozyme research and application, including antimicrobial therapy, biosensing, and environmental remediation. The platform improves data accessibility, reduces experimental redundancy, and speeds up the translation of discoveries into practical use. By bridging the data fragmentation and predictive limitations of existing systems, AI-ZYMES establishes a new benchmark for AI-driven advancements in nanomaterials.

Nanomineralzyme as a novel sustainable class of nanozyme: Chalcopyrite-based nanozyme for the visual detection of total antioxidant capacity in citrus fruit

Chemically-synthesized Nanozymes that are widely used as alternatives to enzymes face challenges such as high precursor costs, complex preparation processes, and limited catalytic efficiency. To overcome these drawbacks, we introduce naturally derived nanozymes, nanomineralzymes, as a promising alternative, offering benefits like affordability, cost-effectiveness, and scalability. Chalcopyrite (CP, CuFeS2) was sourced from a mineral deposit, and CP nanoparticles were produced by milling. These nanoparticles exhibited strong peroxidase-like activity, achieving a low Michaelis-Menten constant using 3,3',5,5'-tetramethylbenzidine as a substrate. Characterizations revealed the presence of cuprous, cupric, ferrous, and ferric ions in the CP mineral. The proposed mechanism involves an enhanced Fenton and Fenton-like process due to the metal ions' multi-valence states. CP nanozyme activity was inhibited to produce radicals due to hydrogen atom transfer and single electron transfer with ascorbic acid, glutathione and cysteine. The CP mineralzyme-based total antioxidant capacity probe was successfully used for detection of TAC in citrus fruits.

Amino acid-based, sustainable organic nanozyme and integrated sensing platform for histamine detection

Inorganic nanozymes hold promise for biomolecule sensing but face challenges like complex fabrication, toxicity, and low sustainability, limiting their use. To overcome these, a sustainable organic nanozyme (OA nanozyme) was created using amino acids and a biocompatible polymer for effective histamine detection. The OA nanozyme exhibits peroxidase-like activity and was fabricated through a single chelation/polymer entanglement method, enabling rapid production (within 3 h) with uniform morphology (≤100 nm diameter) and a negative surface charge at neutral pH. It shows decent kinetic performance (Km = 0.009 mM for H2O2) and biocompatibility, making it suitable for biological applications. The OA nanozyme achieved high sensitivity for histamine detection (LOD: 21.37 pgmL-1) with excellent selectivity and specificity against related molecules. The system's ability to detect histamine in real food samples (e.g., spinach) was also confirmed. These findings indicate that the OA nanozyme holds significant potential for broader applications in food safety and quality assurance.

Apical Anchoring and Cofactor Customizing To Achieve Ultrahigh Active Nanoenzymes for Removing O2 Interference in Glucose Electro-oxidation

Noble metal nanozymes (NMs) are promising alternatives to the fragile glucose oxidase (GOD), however, in all previously reported NMs, O2 consumes electrons from glucose by competing with electrodes, which remarkably limits the Faraday efficiency. The low NM utilization rate and sluggish mass transfer severely limit the electrocatalytic activity. Herein, we report the first Au nanozyme that can catalyze glucose electro-oxidation (GEO) via a distinctive O2 immune pathway with record-breaking mass activity based on apical anchoring and cofactor customization. Strategically, we design a cofactor of lipoic acid (ALA) that can accept electrons from glucose in preference to O2 for Au nanoparticles, and anchor AuNPs/ALA on top of sheared hydrophilic carbon nanotubes (T-SCNT/AuNPs/ALA). Mechanistically, ALA has highly reversible redox activity, and its reduction state is insensitive to O2, thus, it can mediate direct electron transfer between the electrode and AuNPs. In addition, compared to CNT/AuNPs, T-SCNT/AuNPs/ALA has a larger electrochemical surface area, lower charge transfer resistance, and superior hydrophilicity, which are favorable for improving the reaction rate and efficiency. Notably, this strategy can be used to design bilirubin oxidase mimics (T-SCNT/AuNPs/rutin), whose oxygen reduction activity significantly surpasses that of bilirubin oxidase. Consequently, compared to CNT/AuNPs, T-SCNT/AuNPs/ALA boosts the Faraday efficiency of GEO from 50% to 98%, shows a 755-fold increase in mass activity, and enables glucose biofuel cells to offer a 118-fold increase in power density. To the best of our knowledge, this is the first study to achieve a non-O2-interference GEO nanozyme by synergistically regulating the cofactor and catalytic interface and will guide the engineering of demand-specific electrocatalysts.

Amino-Acid-Engineered Bionanozyme Selectivity for Colorimetric Detection of Human Serum Albumin

Nanozymes are emerging nanomaterials owing to their superior stability and enzyme-mimicking catalytic functions. However, unlike natural enzymes with inherent amino-acid-based recognition motifs for target interactions, manipulating nanozyme selectivity toward specific targets remains a major challenge. In this study, we introduce the de novo strategy using the supramolecular assembly of l-tryptophan (l-Trp) as the recognition amino acid with copper (Cu) ions for creating a human serum albumin (HSA)-responsive bionanozyme. This amino-acid-engineered bionanozyme enables selective colorimetric detection of HSA, a critical urinary biomarker for kidney diseases, overcoming the challenge that HSA is neither a typical substrate nor an inhibitor for most nanozymes. Kinetic studies and competitive tests reveal that HSA subdomain IIIA binding to l-Trp sites limits the electron-transfer-induced structural changes of l-Trp-Cu chelate rings, resulting in noncompetitive inhibition. This inhibition effect is significantly stronger than that observed for canonical amino acids, common proteins, and urinary interference species. Colorimetric monitoring of bionanozyme activity enables sensitive HSA detection with a detection limit of 1.3 nM and a quantification range of 2 nM to 10 μM. This approach is exceptionally more sensitive and offers a broader detection range compared to conventional colorimetric and fluorescent methods, suitable for diagnostics across various clinical stages of disease. This innovative rational strategy to designing and manipulating selective nanozyme-target interactions not only addresses the limitations of nanozymes but also expands their precise applications in complex biological systems.

S-Modified MOF Nanozyme Cascade System with Multi-Enzyme Activity for Dual-Mode Antibiotic Assay

The judicious utilization of antibiotics has established a robust bulwark for human health. However, their improper usage has engendered deleterious ramifications on the environment, underscoring the imperative for developing efficacious and cost-effective detection and degradation platforms. This study presents a sulfur-modified iron-cobalt bimetallic single-atom nitrogen-doped carbon catalyst (S-FeCo-NC) with a noncopper active center. In contrast to conventional laccase, which utilizes copper as its active center, the S-FeCo-NC catalyst exhibits multiple enzyme activities, including laccase-like, peroxidase-like, and catalase-like functions, with iron and cobalt serving as the active centers. As a proof of concept, the combined laccase-like and catalase-like functions of S-FeCo-NC were used as independent signal outputs, while a multienzyme cascade dual-mode assay system was designed for the rapid detection of tetracycline (TC) in combination with peroxidase-like enzymes. In this system, oxygen directly participated in the catalytic process of laccase-like as an electron acceptor, while catalase-like peroxidase efficiently catalyzed the production of O2 from H2O2. The elevated concentration of O2 offered a unique advantage for the increased catalytic activity of the laccase-like enzyme, which outputs visually resolved colorimetric signals using stable 4-aminopyridine with oxidized TC. Furthermore, the peroxidase-like activity of S-FeCo-NC catalyzed the generation of OH radicals with strong oxidative properties, and these radicals carried out effective oxidative decomposition of TC. The signal output of the response of the catalytic process was performed using differential pulse cyclic voltammetry, which further improved the sensitivity and accuracy of the detection. The experimental findings demonstrate that the detection system exhibits a favorable response signal to TC within the range of 0.005-500 μM, with its detection range reaching 0.5-500 and 0.005-1.00 μM, respectively, and the detection limit is as low as 0.22 μM and 1.68 nM, respectively. This cascade dual-mode detection system, based on multienzyme activity, has been shown to significantly enhance the catalytic activity of laccase, while also demonstrating stability in a lower detection range. This suggests that it may offer a novel approach for the sensitive detection and degradation of environmental pollutants.

Nanoscale CaO2-Loaded Surface-Engineered Iodine-125 Seed with Sustained Self-Oxygenation for Sensitized Tumor Brachytherapy

Iodine-125 (125I) brachytherapy (BT) is renowned for its precision and effectiveness in delivering localized radiation doses to solid tumors. However, the therapeutic efficacy of traditional125I seed is often limited due to the inherent and acquired radioresistance. Based on the importance of tumor hypoxia in radioresistance, a novel "in situ oxygen-supplement" surface-modified radioactive 125I seed (125I@TNT-CaO2) is designed and constructed to overcome hypoxia-induced radioresistance in tumor BT. Titanium dioxide nanotubes (TNTs) are modified on the titanium shell of traditional 125I seed and loaded with nanoscale calcium peroxide (CaO2), further leading to a sustained release of O2. This in situ oxygen delivery system sensitizes hypoxic tumor regions to 125I BT, significantly improving therapeutic efficacy by inducing more ROS generation and DNA damage. Both in vitro and in vivo experiments demonstrate enhanced tumor suppression and apoptosis, with elevated O2 levels further inhibiting hypoxia-inducible factor 1-alpha (HIF-1α) and its associated signaling pathways. This innovative 125I@TNT-CaO2 seed presents a promising paradigm to enhance the effectiveness of BT by reversing hypoxia-mediated resistance.

Nanozymes meet hydrogels: Fabrication, progressive applications, and perspectives

Nanozyme, a class of emerging enzyme mimics, is the nanomaterials with enzyme-mimicking activity, which has obtained significant and widespread applications in various fields. However, they still face many challenges in practical applications (e.g., instability and low biocompatibility in the physiological environments), which affect their widespread applications to a certain extent. Hydrogels with superior performances (e.g., the controllable degradability, good biocompatibility, hydrophilic properties, and adjustable physical properties) may provide a promising strategy to make up the existing deficiencies of nanozymes in practical applications. Thus, the sapiential combination of nanozymes with hydrogels endows nanozyme hydrogels with both characteristics of nanozymes and properties of hydrogels, making nanozyme hydrogels become novel multifunctional materials. In this review, we comprehensively summarizes the preparation, properties, and progressive applications of nanozyme hydrogels. First of all, the main design and preparation strategies of nanozyme hydrogels are considerately summarized. Then, the properties of different nanozyme hydrogels are introduced. In addition, sophisticated applications of nanozyme hydrogels in the fields of biosensing, biomedicine applications, and environmental are comprehensively summarized. Most importantly, future obstacles and chances in this emerging field are profoundly proposed. This review will provide a new horizon for the development and future applications of novel nanozyme hydrogels.

Design and performance analysis of multi-enzyme activity-doped nanozymes assisted by machine learning

Traditional design approaches for nanozymes typically rely on empirical methods and trial-and-error, which hampers systematic optimization of their structure and performance, thus limiting the efficiency of developing innovative nanozymes. This study leverages machine learning techniques supported by high-throughput computations to effectively design nanozymes with multi-enzyme activities and to elucidate their reaction mechanisms. Additionally, it investigates the impact of dopants on the microphysical properties of nanozymes. We constructed a machine learning prediction framework tailored for dopant nanozymes exhibiting catalytic activities like to oxidase (OXD) and peroxidase (POD). This framework was used to evaluate key catalytic performance parameters, such as formation energy, density of states (DOS), and adsorption energy, through density functional theory (DFT) calculations. Various machine learning models were employed to predict the effects of different doping element ratios on the catalytic activity and stability of nanozymes. The results indicate that the combination of machine learning with high-throughput computations significantly accelerates the design and optimization of dopant nanozymes, providing an efficient strategy to address the complexities of nanozyme design. This approach not only boosts the efficiency and capability for innovation in material design but also provides a novel theoretical analytical avenue for the development of new functional materials.

Single-Site Iridium Catalyst on Metal-Organic Framework as Light-Responsive Oxidase-Like Nanozyme with High Stability for Colorimetric Detection of Antioxidant Capacity

The design and synthesis of advanced artificial enzymes are essential for developing promising surrogates for natural enzymes. Herein, we reported an efficient and facile strategy for the synthesis of a single-site iridium catalyst on a metal-organic framework (UiO-67@Ir) as a light-responsive oxidase-like nanozyme, in which UiO-67 was utilized as a host template and the iridium(III) complex was utilized as a photosensitizer with a light-responsive property. A single-site iridium catalyst on UiO-67@Ir by the coordination of the Ir (III) complex with the nitrogen atom of UiO-67 is confirmed by X-ray photoelectron spectroscopy and aberration-corrected atomic-resolution high-angle annular dark-field scanning transmission electron microscopy. The UiO-67@Ir possesses remarkable light-responsive oxidase-like activity and good cycle and storage stability. Excellent catalytic activity toward the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) was obtained with 0.204 mM of Michaelis-Menten constant (Km) due to its large surface areas and abundant active sites. TMB was oxidized by UiO-67@Ir in the presence of O2 under light irradiation through the formation of both •OH and O2•- by type I photosensitization processes (electron transfer) and the formation of 1O2 by type II photosensitization processes (energy transfer). Moreover, a sensitive colorimetric method was developed for the detection of antioxidants with a detection limit of 0.6, 0.5, and 0.3 μM for ascorbic acid, glutathione, and cysteine, respectively. The total antioxidant capacity in fruit and drink samples were analyzed with desirable results. This study not only enlightens the novel nanozyme designing strategies but also suggests its good analytical performance in colorimetric sensing.

Multifamily Nanozymes for Sustainable and Eco-Friendly Marine Antifouling

Marine pollution poses a serious threat to the ecological environment, destroys habitats, reduces biodiversity, and negatively impacts fisheries and human health. Therefore, development of efficient marine antifouling strategies is of great significance. This study introduces manganese selenide nanoflowers (MnSe NFs) as multifamily nanozymes, exhibiting phosphoesterase-, oxidase-, and peroxidase-like activities. The catalytic mechanism of this multifamily nanozyme was elucidated using density functional theory calculations and spectroscopic analyses. Laboratory tests demonstrated that MnSe NFs exhibit strong antifouling efficacy against biofilms formed by Staphylococcus aureus and Pseudomonas aeruginosa, achieving an antibacterial rate exceeding 99.999%. In marine antifouling scenarios, ship hulls coated with MnSe NF-based paints significantly inhibited biofilm formation for over 90 days, offering advantages in environmental friendliness, sustainability, and cost-effectiveness. This study provides a novel approach for controlling marine biofilms and highlights the potential of multifamily nanozymes as a sustainable and eco-friendly solution for antifouling technologies.

Refinement of Synthetization Parameters for High Laccase-Like Activity of Imidazole-Copper (II) Nitrate Trihydrate Nanozyme Towards an Efficient Biomimetic Nanozyme

Laccase's industrial application is hindered by its sensitivity and low stability to extreme conditions. To overcome these limitations, the development of biomimetic nanozymes is gaining momentum. Nevertheless, developing multifunctional nanozymes with high laccase-like activity poses several challenges. This study focused on optimizing the synthesis of imidazole-copper (II) nitrate trihydrate (I-Cu) nanozymes and characterizing its physicochemical properties. Key synthesis parameters (precursor amount, incubation time, and oven temperature) were optimized. I-Cu nanozymes were synthesized in a Teflon-lined autoclave via water-induced precipitation of Cu2+ and imidazole, mimicking the N-Cu coordination found in laccase's active sites. Initial screenings revealed the superior catalytic activity of I-Cu nanozymes synthesized using methanol compared to ethanol, and a smaller nano-scale size than laccase. FTIR analysis confirmed the presence of similar chemical components as laccase (C44H69N11O20), verifying I-Cu nanozyme's capability to degrade phenolic compounds, and imidazole did not decompose throughout the synthesis process. The optimized I-Cu nanozyme demonstrated higher catalytic activity (6.569 UA), oxidation efficiency (Vmax of 0.00893 mM/min and Km of 2.4020 mM), and greater stability under varying pH, temperature, and storage conditions, compared to laccase. Conclusively, the optimized I-Cu nanozyme, with a 6.00-fold increase in catalytic activity compared to previous studies, as well as 1.69-fold higher Km, and 2.08-fold higher Vmax compared to laccase, shows promise as a wastewater treatment alternative. Its enhanced performance, achieved with fewer precursors through synthesis optimization, highlights the potential of lesser-known biomimetic nanozymes and underscores the importance of refining the synthesis parameters.

Gold nanozymes for efficient degradation of organic dye pollutants: outperforming natural enzymes

Nanozymes (NZs) are raising increasing interest as effective tools for the degradation of organic pollutants dispersed in the environment. In particular, noble-metal NZs are extremely efficient and versatile, thanks to their multi-enzymatic activities, wide pH operational range, and thermal stability. However, whilst multifunctionality can be a key asset of NZs in some applications (e.g., by intrinsic self-cascade/tandem reactions), the "internal" competition between their different catalytic activities may strongly limit their specific efficiency towards some targets. In this scenario, a deep comprehension of their catalytic mechanisms and careful optimization of the operating conditions are crucial to disclose their full potential and maximize their performances. Here, we analyzed the ability of gold, palladium, and platinum NZs to degrade model organic pollutants of industrial relevance, i.e. rhodamine B, methylene blue, and methyl orange. Interestingly, we found that AuNZ is very efficient in degrading all three dyes via peroxidase-like activity, unlike the natural enzyme (horseradish peroxidase - HRP), which displayed weak degradative capabilities. On the other hand, Pd and PtNZs experience the internal competitive catalase-like reaction, strongly limiting their dye degradation performances. The mechanism underlying AuNZ's ability to degrade the synthetic dyes was investigated, revealing the preferential reactivity with the aromatic structures of the molecules. We also developed a proof-of-concept AuNZ-based dye-degrading filter system, showing excellent dye removal capability and good recyclability, even in real environmental samples.

Fluorescent Fingerprint Identification of Protein Structural Changes and Disease-Specific Amyloid Beta Aggregates Based on a Single-Nanozyme Sensor Array

The misfolding of amyloid β (Aβ) peptides into an aggregation state is a central hallmark of the onset of Alzheimer's disease (AD). However, conventional methods are mainly focused on detecting a specific Aβ peptide, which makes it difficult to recognize multiple analytes with different topological features and unfolded states at the same time. Here, we propose a simple and universal sensing strategy to construct a fluorescence sensor array by using a single-nanozyme probe combined with three fluorescent substrates as three recognition units to probe the protein structural changes and identify between multiple Aβ assemblies. In this sensor system, the fingerprint-like patterns are produced from the nonspecific interactions between topological proteins and the sensing units. As a result, this sensor array can accurately identify 13 kinds of proteins and their mixtures at different ratios. Moreover, the sensor array can discriminate against proteins with unfolded states and diverse conformational forms. Most importantly, the sensor array successfully distinguishes between multiple Aβ species, even in artificial cerebrospinal fluid samples and human serum samples. This work provides an attractive and reliable strategy for predicting pathologically relevant proteins and clinical diagnosis of AD.

Nanozymes for Treating Ocular Diseases

Nanozymes, characterized by their nanoscale size and enzyme-like catalytic activities, exhibit diverse therapeutic potentials, including anti-oxidative, anti-inflammatory, anti-microbial, and anti-angiogenic effects. These properties make them highly valuable in nanomedicine, particularly ocular therapy, bypassing the need for systemic delivery. Nanozymes show significant promise in tackling multi-factored ocular diseases, particularly those influenced by oxidation and inflammation, like dry eye disease, and age-related macular degeneration. Their small size, coupled with their ease of modification and integration into soft materials, facilitates the effective penetration of ocular barriers, thereby enabling targeted or prolonged therapy within the eye. This review is dedicated to exploring ocular diseases that are intricately linked to oxidation and inflammation, shedding light on the role of nanozymes in managing these conditions. Additionally, recent studies elucidating advanced applications of nanozymes in ocular therapeutics, along with their integration with soft materials for disease management, are discussed. Finally, this review outlines directions for future investigations aimed at bridging the gap between nanozyme research and clinical applications.

Piezoelectric Biomaterial with Advanced Design for Tissue Infection Repair

Bacterial infection has become the most dangerous factor in tissue repair, which strongly affects the tissue regeneration efficiency and wellness of patients. Piezoelectric materials exhibit the outstanding advantage of producing electrons without external power supply. The ability of electron enrichment and reactive oxygen species generation through noninvasive stimulations enables piezoelectric materials the potential applications of antibacterial. Many studies have proved the feasibility of piezoelectric materials as a functional addition in antibacterial biomaterial. In fact, numerous piezoelectric materials with ingenious designs are reported to be effective in antibacterial processes. This review summarizes the antibacterial mechanisms of piezoelectric, illuminating their potential in combating bacteria. Recent advancement in the design and construction of piezoelectric biomaterial including defect engineering, heterojunction, synergy with metal and the composite scaffold configuration are thoroughly reviewed. Moreover, the applications and therapeutic effects of piezoelectric materials in common tissues with antibacterial requirements are introduced, such as orthopedics, dental, and wound healing. Finally, the development prospects and points deserving further exploration are listed. This review is expected to provide valuable insight into the relationship between antibacterial processes and piezoelectric materials, further inspiring constructive development in this emerging scientific discipline.

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.

Nanozyme-Enabled Biomedical Diagnosis: Advances, Trends, and Challenges

As nanoscale materials with the function of catalyzing substrates through enzymatic kinetics, nanozymes are regarded as potential alternatives to natural enzymes. Compared to protein-based enzymes, nanozymes exhibit attractive characteristics of low preparation cost, robust activity, flexible performance adjustment, and versatile functionalization. These advantages endow them with wide use from biochemical sensing and environmental remediation to medical theranostics. Especially in biomedical diagnosis, the feature of catalytic signal amplification provided by nanozymes makes them function as emerging labels for the detection of biomarkers and diseases, with rapid developments observed in recent years. To provide a comprehensive overview of recent progress made in this dynamic field, here an overview of biomedical diagnosis enabled by nanozymes is provided. This review first summarizes the synthesis of nanozyme materials and then discusses the main strategies applied to enhance their catalytic activity and specificity. Subsequently, representative utilization of nanozymes combined with biological elements in disease diagnosis is reviewed, including the detection of biomarkers related to metabolic, cardiovascular, nervous, and digestive diseases as well as cancers. Finally, some development trends in nanozyme-enabled biomedical diagnosis are highlighted, and corresponding challenges are also pointed out, aiming to inspire future efforts to further advance this promising field.

Ce12V6 Clusters with Multi-Enzymatic Activities for Sepsis Treatment

Artificial enzymes, especially nanozymes, have attracted wide attention due to their controlled catalytic activity, selectivity, and stability. The rising Cerium-based nanozymes exhibit unique SOD-like activity, and Vanadium-based nanozymes always hold excellent GPx-like activity. However, most inflammatory diseases involve polymerase biocatalytic processes that require multi-enzyme activities. The nanocomposite can fulfill multi-enzymatic activity simultaneously, but large nanoparticles (>10 nm) cannot be excreted rapidly, leading to biosafety challenges. Herein, atomically precise Ce12V6 clusters with a size of 2.19 nm are constructed. The Ce12V6 clusters show excellent glutathione peroxidase (GPx) -like activity with a significantly lower Michaelis-Menten constant (Km, 0.0125 mM versus 0.03 mM of natural counterpart) and good activities mimic superoxide dismutase (SOD) and peroxidase (POD). The Ce12V6 clusters exhibit the ability to scavenge the ROS including O2 ·- and H2O2 via the cascade reactions of multi-enzymatic activities. Further, the Ce12V6 clusters modulate the proinflammatory cytokines including tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β) and consequently rescue the multi-organ failure in the lipopolysaccharide (LPS)-induced sepsis mouse model. With excellent biocompatibility, the Ce12V6 clusters show promise in the treatment of sepsis.

A Nattokinase-Loaded Nanozyme for Alleviating Acute Myocardial Infarction via Thrombolysis and Antioxidation

Acute myocardial infarction (MI) induced by thrombus formation is a prevalent cardiovascular disorder, and thrombolytic therapy continues to be a principal treatment modality. Prior research indicates a substantial association among MI, thrombosis, and the activation of oxidative stress pathways. The effectiveness of current thrombolytic drugs is relatively constrained, and the need for innovative and versatile thrombolytic medications remains critical. Nattokinase (NK) is a naturally-occurring enzyme known for its thrombolytic characteristics. Nonetheless, nattokinase's limited stability and susceptibility to inactivation in biological systems have impeded its clinical utility. This study designs a manganese oxide nanozyme (MnOx) loaded with NK (MnOx@NK), which exhibits both antioxidant and thrombolytic function. The administration of MnOx@NK through tail vein injection significantly restores vascular function and further reduces myocardial injury in a mouse model of myocardial infarction, demonstrating a pronounced protective effect against oxidative stress. These findings indicate that nattokinase-loaded nanozymes can be a promising approach for treating acute myocardial infarction, providing a new strategy for clinical application.

Onion-like carbon based single-atom iron nanozyme for photothermal and catalytic synergistic antibacterial application

Nanozymes with oxidase (OXD)-like activity have emerged as promising antibacterial agents due to their capability of catalyzing atmospheric O2 to generate highly active free radicals. However, the precise engineering of functional nanozyme at the atomic level for antibacterial therapy presents a challenge. Here, atomically dispersed Fe atoms were loaded onto onion-like carbon (OLC) through a ligand-assisted calcination strategy, yielding a single-atom nanozyme (FeSA-OLC) with enhanced oxidase-like activity. The FeSA-OLC could catalyze the decomposition of O2 to produce active hydroxyl radicals (·OH) owing to the fully exposed Fe atoms and a highly curved carbon shell. Density functional theory calculation revealed that the single-atom Fe sites facilitated the generation of free radical species by promoting the adsorption and cleavage of OO bond. Meanwhile, the FeSA-OLC exhibited a notable photothermal conversion efficiency of 66.48% under near-infrared laser irradiation. Furthermore, in vitro experimental results demonstrated a synergistic antibacterial effect towards Escherichia coli due to the photothermal-enhanced oxidase-like activity. Overall, this work introduced a strategy to develop OLC-based single-atom nanozyme, thereby offering new avenues for photothermal-augmented antibacterial therapy.