Defect Engineering Enables Synergistic Action of Enzyme-Mimicking Active Centers for High-Efficiency Tumor Therapy

Coordination-driven room-temperature phosphorescent carbon dot nanozymes for dual-mode glutathione detection

Integrating long-lived room-temperature phosphorescence (RTP) into nanozymes to build multifunctional nanozymes can benefit biomedical analysis by expanding sensing modes and developing advanced sensing strategies but it is challenging. Herein, a general strategy for fabricating phosphorescent nanozymes by anchoring Co-Nx active centers on SiO2 nanospheres with carbon dots (CDs) encapsulated inside (CDs@SiO2@Co) is developed for dual-mode colorimetric-phosphorescent detection of glutathione (GSH). Specifically, surface Co-Nx active centers enhanced O2 adsorption and activation (O2 to 1O2), providing oxidase-like activity to induce the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB), generating a distinct colorimetric signal. The SiO2 layer inhibited non-radiative transitions of the CDs to promote RTP, and spatially separated Co ions from CDs to prevent RTP quenching caused by Co-CD interactions, resulting in CDs@SiO2@Co with long-lived RTP (lifetime: 1.14 s), providing a phosphorescent channel free from autofluorescence interference. Upon introduction of GSH, the color product-oxidized TMB (oxTMB) was reduced, and the quenched RTP caused by the oxTMB internal filter effect was restored. Based on this principle, a sensitive and reliable dual-mode colorimetric-phosphorescent method was developed for detecting GSH in plasma and cells. Furthermore, owing to the tunable optical properties of CDs and the flexibility of substituting metal active centers, this strategy can be extended to construct various phosphorescent nanozymes with adjustable RTP emission wavelengths and diverse enzyme-like activities, advancing the development of nanozymes and bioanalytical platforms.

Biocascade-inspired amplified oxygen vacancy effect on facet-engineered BiOI for ultrasensitive photoelectrochemical detection of 8-oxoguanine DNA glycosylase

Sensitive detection of 8-oxoguanine DNA glycosylase 1 (hOGG1) activity is essential for early cancer screening and therapy, yet the potential of photoelectrochemistry (PEC) for hOGG1 detection is untapped. Herein, we explore a new bioreaction for sensitive PEC detection of hOGG1 through biocascade reaction provoked amplified oxygen vacancy (OV) effect on facet-engineered BiOI. Specifically, the recognition of hOGG1 activated the catalytic peptide hydrolysis reaction of thrombin (Thr), producing the OV stimulator p-aminophenol (AP). AP was recycled via the diphosphatase (DI, EC 1.6.99.2) mediated reaction, inducing the formation of abundant surface OV on BiOI with exposed (110) facet (BI-110). This process strikingly enhanced the carrier separation efficiency and augmented the photocurrent gain, enabling highly sensitive detection of hOGG1 with a linear range of 1.0 × 10-4 to 80 U/mL and a low detection limit of 2.0 × 10-5 U/mL. This study addresses the challenge of developing effective PEC assays for hOGG1 by elucidating a new principle of the biocascade reaction-sparked OV effect with facet selectivity, thus filling a gap in PEC detection method for this enzyme.

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.

Dual nanozyme sensor enables rapid at-home cancer surveillance

Early detection of cancer is critical for improving patient survival rates, and current in vitro diagnostic methods show great potential, particularly for point-of-care applications. However, challenges such as time consumption, high costs, and reliance on sophisticated equipment limit their widespread use, especially in resource-limited regions. Here, we have developed a smartphone-assisted miniaturized analytic device that addresses these limitations, offering a portable, cost-effective solution for at-home, rapid cancer screening. Employing a hybrid nanozyme (AuNP@Cu2O-His) with a dual absorption design, this device enables reference-free radiometric quantification of multiple cancer biomarkers in serum down to femtomolar levels using aptamer-based recognition. Specifically, it achieves limits of detection (LOD) of 18.75 pg/mL for prostate-specific antigen (PSA), 110.31 pg/mL for alpha-fetoprotein (AFP), and 42.89 pg/mL for carcinoembryonic antigen (CEA), as determined by the 3σ/K method. Clinical sample analysis confirms the reliability of the device, with results closely matching clinical reports (relative errors below 6%). These findings highlight the potential of this robust, portable platform for early cancer detection in both clinical and resource-limited settings, enabling convenient and effective point-of-care diagnostics.

Nanoarchitectured biomass-waste derived activated charcoal nanozymes and its application in visual analysis of nitrite in pickled food

The emerging field of nanozymes has introduced unprecedented opportunities and challenges for activated charcoal materials derived from biomass waste. By incorporating specific nanostructures or elements, it is possible to overcome the limitations of traditional activated charcoal, such as insufficient catalytic active sites and poor electron transfer efficiency, thereby unlocking its full potential for various applications. In this study, we successfully synthesized trace Fe-doped activated charcoal (Fe-AC) with a graphene-like structure from biomass waste. The Fe atoms were uniformly dispersed on the activated charcoal support, which possessed a high surface area. This not only significantly increased the number of catalytic active sites but also enhanced electron transfer efficiency, substrate mobility, and collision probability. Compared to pristine activated charcoal, the synthesized Fe-AC exhibited multiple enzyme-mimetic activities, including oxidase-like, peroxidase-like, and catalase-like activities. By leveraging its peroxidase-like activity in conjunction with nitrite-specific diazotization reactions, we developed a portable, smartphone-assisted, on-site ratiometric colorimetric hydrogel sensor for nitrite detection. Utilizing smartphone-based digital imaging, this sensor enabled the quantitative analysis of nitrite at concentrations ranging from 1 to 200 μmol/L, with a detection limit as low as 1 μmol/L. The approximate range of hazardous nitrite concentrations could be easily identified with the naked eye, and the proposed strategy was successfully applied to real sample analysis. This sensor not only maximizes the utilization of waste resources, thereby reducing production costs, but also offers greater economic feasibility and environmental sustainability. Given these advantages, it holds promise for broader applications in various fields.

MXene Loaded With Cu(2- x )Se Nanozyme for Nanocatalytic Tumor Therapy

Traditional tumor treatments (surgery, radiotherapy, chemotherapy, etc.) have certain limitations and can have serious negative effects, such as difficulty in cutting out tumors, damage to normal tissues, and complications. Ordinary nanozymes have low catalytic activity and require higher doses for treatment, which can increase in vivo toxicity and side effects. To address these limitations, we developed a Ti3C2 MXene-based nanocomposite (Ti3C2/Cu(2- x )Se) integrating Cu(2- x )Se nanozymes with dual enzyme-mimicking activities (catalase and peroxidase) and MXene's photothermal properties. The Cu(2- x )Se component catalyzes the decomposition of tumor-overexpressed H2O2 into O2 and cytotoxic ·OH, alleviating hypoxia while inducing oxidative stress. Simultaneously, MXene's high surface area and photothermal capability enhance nanozyme stability, biocompatibility, and catalytic efficiency under near-infrared irradiation. Notably, the photothermal effect amplifies enzymatic activity, enabling synergistic nanocatalytic-photothermal therapy. This synergy not only degrades glutathione to suppress tumor antioxidant defenses but also achieves targeted tumor ablation with reduced dosage requirements. Our work highlights a rational design of MXene-based nanozymes for enhanced multimodal tumor therapy, offering a paradigm for nanocomposite-driven disease treatment.

Integrating Vacancies and Defect Levels in Heterojunctions to Synergistically Enhance the Performance of H2S Chemiresistors for Periodontitis Diagnosis

Exhaled breath is considered an important source of samples and a reservoir of biomarkers, especially for disease diagnosis. In this study, we developed an ultrasensitive point-of-care gas sensor for the analysis of hydrogen sulfide (H2S), which is a typical biomarker for periodontitis. A high-performance metal oxide semiconductor (MOS)-based chemiresistive H2S sensor was developed by integrating Fe-doped MoO3-x onto TiO2 nanotube arrays. The substitution of Fe atoms into MoO3-x not only induced oxygen vacancies, but also generated defect levels in the MoO3-x/TiO2 heterostructure, thus synergistically activating the gas sensing reaction at room temperature under ambient light. The resulting gas sensor exhibited ultrahigh sensitivity, fast response/recovery ability, and wide-range response to H2S concentrations up to 400 ppm. Furthermore, the sensing device maintained more than 95% of its original response at 70% relative humidity. With a subparts-per-billion limit of detection (the LOD for H2S was 0.34 ppb), the present sensor represents the most sensitive H2S chemiresistor reported to date for room-temperature, real-time monitoring of H2S concentration changes in the breath of healthy subjects, as well as for distinguishing breath samples of periodontitis patients and healthy individuals. This study utilizes the synergistic action of defects to provide an effective route for developing MOS-based ultrasensitive H2S sensors for periodontitis diagnosis.

Integrating Ferroelectric Fields with Active Sites for the Construction of Highly Efficient Nanozymes

Enhancing nanozymes' catalytic activity is challenging yet crucial for practical applications. Herein, inspired by the electrostatic preorganization effect in the catalytic process of natural protein enzymes, a nanozyme is constructed by decorating ferroelectric BaTiO3 nanoparticles (BTO) with hemin, which is often regarded as the active site of natural horseradish peroxidase (HRP). The Hemin-BTO nanozyme demonstrates excellent peroxidase-like (POD-like) activity with the catalytic constant (Kcat) up to 9.71 × 105 s-1 and 1.41 × 106 s-1 for TMB and H2O2 substrates, which is ca. 240-fold and 400-fold greater than that of HRP. Theoretical studies utilizing Density Functional Theory calculations revealed the underlying mechanism. The spontaneous polarization electric field of BTO adjusts the internal electrostatic field of the active site hemin, thereby enhancing the affinity between the Hemin-BTO nanozyme and the substrate. Simultaneously, the existence of hemin reduced the recombination of BTO charge carriers, accelerated electron transfer, and thus promoted the generation of reactive oxygen species, effectively enhancing its POD-like activity. In addition, Hemin-BTO has been successfully used to establish an immunoassay of human brain natriuretic peptide. This work presented a feasible strategy to construct nanozymes with highly catalytic activity by integrating the ferroelectric fields with the active site of natural enzymes.

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

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

Photothermal functionalized antibacterial packaging film with controllable release capability for fruit preservation

The traditional contact release active packaging film is easily restricted by the strict storage environment and designing a more intelligent release system to achieve lasting food preservation is still a challenge. Herein, a light-responsive thermal-controlled curcumin release packaging film was fabricated by integrating chitosan with Cu-MoOx and curcumin (CS/CMC). The addition of filler did not destroy the crystal structure and thermal stability of the chitosan matrix. CS/CMC film also possessed satisfactory visual identifiability (ΔE* ≥ 14.98), good light transmittance (T660 ≥ 79.99 %), enhanced mechanical properties (≥ 48.21 MPa), and excellent barrier performance against ultraviolet light (T280 ≤ 29.2 %), and water vapor (≤ 0.74 × 10-10 g m-1 s-1 Pa-1). Additionally, CS/CMC film obtained superior photothermal performance from Cu-MoOx and exhibited good photothermal stability. Benefiting from the photothermal activity, CS/CMC film realizes the intelligent and controllable release of curcumin. The released curcumin and photothermal showed synergistic antibacterial ability with an antibacterial rate of 99.33 % for E. coli and 99.23 % for S. aureus based on CS/CMC0.02 under near infrared (NIR) irradiation. Besides, CS/CMC0.02 film could also efficiently inhibit P. italicum and P. expansum under NIR irradiation. Tangerine treated with CS/CMC0.02 + NIR exhibited a longer shelf life and less nutrient loss than polyethylene (PE) film, verifying the good potential of CS/CMC0.02 as packaging film. Our release active packaging film based on photothermal agent provides a new insight to designing contactless intelligent active packaging.

Oxidative stress-augmented Cu-doped hollow mesoporous carbon nanozyme for photothermal/photodynamic synergistic therapy

Photodynamic therapy (PDT) has witnessed remarkable progress in recent years owing to its specific properties. Given that the antioxidation system of tumor microenvironment (TME) adversely affects treatment outcomes, powerful TME modulators can significantly resolve the limitation of PDT. Herein, we developed a PEG-modified Cu2+-doped hollow mesoporous carbon nanozyme (CHC-PEG) and loaded insoluble photosensitizer IR780 into its pores and cavities to construct the multifunctional nano-system IR780/CHCP. CHC-PEG nanozyme could perform photothermal therapy (PTT) effect and protect IR780 from aggregation-caused quenching (ACQ) effect, while exerting peroxidase (POD)-mimetic activity and the ability of consuming glutathione (GSH) to achieve oxidative stress-augmented PDT effect. When exposed to near-infrared (NIR) light, IR780 was stimulated to produce singlet oxygen (1O2) and CHC-PEG could increase the temperature of TME to exert stronger POD-mimetic activity for producing more hydroxyl radicals (OH), therefore the IR780/CHCP nano-system exhibited remarkable tumor growth inhibition. Benefited by the enhanced synergistic effect, IR780/CHCP exhibited remarkable in vivo tumor growth inhibition, with the tumor inhibition rate of 93 %, and had no significant effect on major organs. Above all, IR780/CHCP could resist the antioxidant system in TME to enhance the level of oxidative stress, thereby enabling effective anti-tumor therapy. This study introduced a novel strategy to effectively promote the synergistic PTT/PDT effect by the enhanced oxidative stress.

Amino Acid-Regulated Biomimic Fe-MOF Nanozyme with Enhanced Activity and Specificity for Colorimetric Sensing of Uranyl Ions in Seawater

Nanozymes are attracting widespread attention as effective alternatives to overcome the limitations of natural enzymes. However, their catalytic performance is unsatisfactory due to the low catalytic activity and specificity. In this work, an efficient metal-organic framework (MOF) nanozyme mimicking the active centers of natural enzymes has been developed and its catalysis mechanism has been thoroughly investigated. The partial histidine- and arginine-doped Fe-MOF (HA Fe-MOF) is demonstrated to activate structure reconstruction with abundant oxygen vacancy generation, which promotes the binding capacity of HA Fe-MOF. The Fe sites in HA Fe-MOF act as catalytic sites for decomposition of H2O2. Intriguingly, histidine and arginine in the HA Fe-MOF can form hydrogen bonds with H2O2 as observed in natural enzymes, constituting a unique microenvironment that increases the local concentration of H2O2. Benefiting from the establishment of such enzyme-mimicking active centers, HA Fe-MOF exhibits high peroxidase-like specificity and activity. In addition, HA Fe-MOF holds great potential for detecting uranyl ions with a limit of detection as low as 0.012 μM, surpassing most reported nanozymes. This work achieves the rational design of highly specific peroxidase-like nanozymes by mimicking the structure-selectivity relationship of natural peroxidases, which provides new insights into the design of nanozymes with advanced configurations.

Recent advances in nano-molybdenum oxide for photothermal cancer therapy

Cancer remains a significant global health challenge, driving the search for innovative treatments. Photothermal therapy (PTT) has emerged as a promising approach, using photothermal agents to convert near-infrared (NIR) light into heat for tumor ablation. Among these agents, nano-molybdenum oxide, particularly non-stoichiometric MoO3-x (0 < x < 1), stands out due to its unique defect structure, strong NIR absorption, high photothermal conversion efficiency (PCE), and pH-responsive degradation. This review summarized recent advancements in nano-molybdenum oxide for PTT, covering its classification, synthesis, surface modification, and tumor-targeting mechanisms. Subsequently, we explored its applications in PTT and combination therapies, evaluated biocompatibility and toxicity, and discussed current achievements, challenges, and future perspectives in cancer treatment.

Charge regulated pH/NIR dual responsive nanoplatforms centered on cuproptosis for enhanced cancer theranostics

Multifunctional nanoplatforms capable of simultaneously executing multimodal therapy and imaging functions are of great potentials for cancer theranostics. We present an elegantly designed, easy-to-fabricate poly(acrylic acid)/mesoporous calcium phosphate/mesoporous copper phosphate nanosphere (PAA/mCaP/mCuP NS) with outstanding pH/NIR-sensitive multimodal-synergic anti-tumor effects. Optimal porous PAA NS scaffolds were prepared at room temperature by balancing the intra-PAA polymer and polymer-solvents Lennard-Jones potentials in a water:isopropyl alcohol (IPA) mix-solvent. Subsequent sponging of Ca2+ and Cu2+, and adsorption of PO43- to the PAA template were achieved through exquisite electrostatic interactions among ions and the ionizable PAA side-chain in an aqueous environment. This forms the basis for the tumor microenvironment pH-triggered release of Cu2+ to induce cuproptosis, as well as the photothermal effect originating from CuP, while Ca2+ can enhance the nanoplatform's biocompatibility and can damage mitochondria when overloaded. Lastly, PAA/mCaP/mCuP NSs still exhibit high drug loading efficiency for doxorubicin (DOX), enabling chemotherapy. Satisfactory anti-tumor effects of these modalities, along with their synergistic effects, were verified both in vitro and in vivo, with the NSs demonstrating good biodegradation in the latter. The fabricated NS itself holds great promise as an anti-tumor nanomedicine, and the thorough mechanical insights into NS formation may inspire the design of next-generation multifunctional nanoplatforms.

Biocatalytic cascade reactions for management of diseases

Biocatalytic cascade reactions, which evolve from the confinement of multiple enzymes within living cells, represent a promising strategy for disease management. Using tailor-made nanoplatforms, reactions induced by multiple enzymes and/or nanozymes can be precisely triggered at pathogenic sites. These promote further cascade reactions that generate therapeutic species prompting effective therapeutic outcomes with minimal side effects. Over the past few years, this approach has seen widespread applications in disease management. This review attempts to critically assess and summarize the recent advances in the use of biocatalytic cascade reactions for the management of diseases. Emphasis is placed on the design of cascade catalytic systems of high efficiency and selectivity and the implementation of specific cascade processes that respond to the endogenous substances produced in the pathological processes. The various types of biocatalytic cascade reactions are outlined according to the timeline of the catalytic steps through a series of reported examples. The challenges and outlook in the field are also discussed to encourage the further development of personalized treatments based on biocatalytic cascade reactions.

Electrocatalytic Conversion of Glucose into Renewable Formic Acid Using "Electron-Withdrawing" MoO3 Support under Mild Conditions

Electrocatalysis is a sustainable and effective approach to produce value-added chemical commodities from biomass, where highly effective catalyst is required. Since transition metal hydroxide is a feasible catalyst for electrochemical biomass conversion, rational optimization of its electrocatalytic activity is highly desired. Herein, electrocatalytic activity of glucose oxidation is significantly optimized by reducing the electron density at Ni active sites, which is achieved by depositing Ni(OH)2 at "electron-withdrawing" MoO3 support (Ni(OH)2MoO3-x). As results, the formation of active sites (NiOOH) and the adsorption of glucose are simultaneously facilitated in Ni(OH)2MoO3-x, which effectively converts glucose to formic acid (FA) with remarkable yield and Faraday efficiency (≈90.5 and 98%, respectively), far superior to conventional β-Ni(OH)2 catalyst (≈22.5 and 58.9%, respectively). In addition to a novel strategy for efficient FA production from glucose, this work offers valuable insights into the rational optimization of electrocatalytic oxidation of biomass-based substrates.

Covalent Coupling-Regulated rGO/VN Nanocomposite Enabling Nitrogen Defects to Remarkably Boost the Peroxidase-Like Catalytic Efficiency for the Ultrasensitive Colorimetric Assay of Uric Acid

It remains challenging to rationally design superior nanozymes and understand the underlying mechanism. Herein, a facile covalent coupling-modulated nitrogen defect is reported for significantly boosting peroxidase (POD)-like activity. Vanadium nitride (VN) nanoparticles are grown on graphene oxide (GO) via C-N bonding to form VN/rGO nanocomposites by varying with the VOx/GO ratio. The initial increasing GO amount enables formation of the C-N bond, dramatically boosting POD-like activity. Nevertheless, with a higher GO amount, the nitrogen defects decrease due to forming mainly V2O3. The defect-rich VN/rGO nanocomposite with 20 wt % GO (VG-2) exhibits the best catalytic efficiency (Vmax/Km = 0.0187 s-1), which is 778-fold higher than that of natural horseradish peroxidase. Theoretical calculations and structure characterization reveal that the rich-N defects originate from VN covalent binding onto rGO with an rich-electron structure, impeding VN agglomeration, which greatly reduces the energy barrier of the rate-determining step of the catalytic reaction. Finally, coupling urate oxidase with VG-2 as an enzyme cascade, an ultrasensitive and selective colorimetric detection was developed for uric acid (UA), one of the indicators of kidney function or gout attacks, with a linear detection ranging 1-100 μM and 0.1-2.5 mM with a limit of detection of 0.24 μM UA (S/N = 3). The proposed method was applicable to detecting UA in human serum samples satisfactorily. This work could inspire more effective insights into designing other robust nanozymes through covalent coupling for a variety of biochemical analysis and biocatalysis applications.

Semiconductor-mediated radiosensitizers: progress, challenges and perspectives

Radiotherapy has become one indispensable treatment strategy for treating malignant tumors. However, the therapeutic effect of radiotherapy is limited due to the low sensitivity and large side effects of existing radiosensitizers. The rapid development of nanotechnology has created opportunities for various novel kinds of radiosensitizers with excellent radiosensitivity to sprout recently. In particular, due to the ease of modification and potential utilization capacity for a multifunctional radiotherapy platform, semiconductor radiosensitizers have attracted more and more attention. Recently, many novel semiconductor based radiosensitizers have been reported, which provides new ideas for the improvement of radiotherapy efficacy. To make further breakthroughs in semiconductor radiosensitizers, a systematic review is urgently needed and is herein provided. This review first elaborates on the principle of semiconductor induced radiosensitization, and then focuses on strategies such as doping and constructing heterojunctions to enhance the radiosensitivity of semiconductors. Next, it introduces in detail the principle and progress of different types of semiconductor radiosensitizers. Finally, challenges and perspectives of semiconductor radiosensitizers are proposed and discussed, offering guidance for future commercial applications of semiconductor radiosensitizers.

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

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

Advancements in NADH Oxidase Nanozymes: Bridging Nanotechnology and Biomedical Applications

Nicotinamide adenine dinucleotide (NADH) oxidase (NOX) is key in converting NADH to NAD+, crucial for various biochemical pathways. However, natural NOXs are costly and unstable. NOX nanozymes offer a promising alternative with potential applications in bio-sensing, antibacterial treatments, anti-aging, and anticancer therapies. This review provides a comprehensive overview of the types, functional mechanisms, biomedical applications, and future research perspectives of NOX nanozymes. It also addresses the primary challenges and future directions in the research and development of NOX nanozymes, underscoring the critical need for continued investigation in this promising area. These challenges include optimizing the catalytic efficiency, ensuring biocompatibility, and achieving targeted delivery and controlled activity within biological systems. Additionally, the exploration of novel materials and hybrid structures holds great potential for enhancing the functional capabilities of NOX nanozymes. Future research directions can involve integrating advanced computational modeling with experimental techniques to better understand the underlying mechanisms and to design more effective nanozyme candidates. Collaborative efforts across disciplines such as nanotechnology, biochemistry, and medicine will be essential to unlock the full potential of NOX nanozymes in future biomedical applications.

A Single-Atom Mn/MoO3- x Nanoagonist for Cascade cGAS/STING Activation in Tumor-Specific Catalytic Metalloimmunotherapy

The cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING) pathway plays a crucial role in initiating anti-tumor immunity. Despite the development of various STING agonists, their effectiveness is often limited by suboptimal activation efficiency and poor sustainability. To address this, a Mn/MoO3- x nanoagonist featuring Mn single-atom sites is presented, designed for cascade cGAS/STING activation in tumor-specific catalytic metalloimmunotherapy. The single-atom nanoagonist (SANA) is meticulously crafted by doping Mn atoms into defective molybdenum oxide (MoO3- x), enabling robust peroxidase-mimicking catalysis and inducing severe double-stranded DNA (dsDNA) damage in tumors. Of note, Mn2+ and MoO4 2- can be responsively released from Mn/MoO3- x SANA and enhance the sensitivity of cGAS to dsDNA. Importantly, MoO4 2- with a relatively slow-release profile and facile cellular accumulation compensates for Mn2+ that has poor cellular accumulation due to continuous efflux, thus continuatively triggering the secretion of type I interferon for beyond 72 h. Remarkably, Mn/MoO3- x SANA significantly inhibits tumor growth and metastasis without supplementary STING agonists or external stimulation. This study offers a promising cascade cGAS/STING activation approach to enhance the efficacy and sustainability of catalytic metalloimmunotherapy.

Fine-Tuning Electron Transfer for Nanozyme Design

Nanozymes, with their versatile composition and structural adaptability, present distinct advantages over natural enzymes including heightened stability, customizable catalytic activity, cost-effectiveness, and simplified synthesis process, making them as promising alternatives in various applications. Recent advancements in nanozyme research have shifted focus from serendipitous discovery toward a more systematic approach, leveraging machine learning, theoretical calculations, and mechanistic explorations to engineer nanomaterial structures with tailored catalytic functions. Despite its pivotal role, electron transfer, a fundamental process in catalysis, has often been overlooked in previous reviews. This review comprehensively summarizes recent strategies for modulating electron transfer processes to fine-tune the catalytic activity and specificity of nanozymes, including electron-hole separation and carrier transfer. Furthermore, the bioapplications of these engineered nanozymes, including antimicrobial treatments, cancer therapy, and biosensing are also introduced. Ultimately, this review aims to offer invaluable insights for the design and synthesis of nanozymes with enhanced performance, thereby advancing the field of nanozyme research.

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

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

Single-atom-doped piezocatalyst induces copper-free cuproptosis in tumor therapy

Cuproptosis, a distinct cell death pathway, has been integrated into nanomedicine for disease theranostics. However, current nanosystems inducing cuproptosis rely on exogenous toxic copper ions, limiting the scope of biomaterials. Developing nanoplatforms that induce cuproptosis without exogenous copper holds substantial promise. Here, we engineered a two-dimensional iron (Fe) single-atom-doped molybdenum disulfide (MoS2) piezocatalyst (Fe-MoS2) for tumor therapy. Incorporating single Fe atoms enhances MoS2 piezoelectric polarization via charge redistribution and modulates Fe and Mo oxidation states, enabling multifaceted enzymatic activities, including peroxidase-, glutathione oxidase-, oxidase-, and catalase-like activities. Upon ultrasound stimulation, the Fe-MoS2 nanocatalyst generates reactive oxygen species and depletes glutathione via synergistic piezocatalytic and enzyocatalytic effects, disrupting copper ion homeostasis and inducing cuproptosis, concurrently triggering ferroptosis and ferritinophagy, which collectively enhances tumor suppression. This study represents the first paradigm to introduce a copper-free piezocatalyst for initiating cuproptosis, substantially advancing the applications of cuproptosis in tumor therapy.

Vacancy engineering enhanced photothermal-catalytic properties of Co9S8-x nanozymes for mild NIR-II hyperthermia-amplified nanocatalytic cancer therapy

While nanozymes are commonly employed in nanocatalytic therapy (NCT), the efficacy of NCT is hampered by the limited catalytic activity of nanozymes and the intricate tumor microenvironment (TME). In this work, we design a high-efficiency nanozyme with NIR-II photothermal property for the mild hyperthermia-augmented NCT. In order to endow a single-component nanomaterial the ability to simultaneously catalyze and exhibit NIR-II photothermal properties, a straightforward template method is utilized to fabricate sulfur vacancies (VS)-doped Co9S8-x nanocages. Introducing VS not only lowers the bandgap structure of Co9S8, enhancing its NIR-II photothermal properties, but also facilitates the control of the Co2+ and Co3+ ratio in Co9S8, leading to a boost in its catalytic activity. Furthermore, the catalytic efficiency of Co9S8-x nanocages was boosted by the mild hyperthermia. Moreover, the Co9S8-x nanocages exhibited high-efficiency GSH-px-mimic catalytic activity, facilitating the cascade amplification of ROS production. Through the integrated multifunctionality of Co9S8-x nanocages, we successfully enhanced the effectiveness of antitumor treatment with a single drug injection and a single 1064 nm laser irradiation for mild hyperthermia-augmented NCT. This work provides a distinct paradigm of endowing nanomaterials with catalytic activity and photothermal property for mild NIR-II PTT-amplified NCT through a vacancy engineering strategy.

Ferrous Tungstate Nanomaterials with Excellent Enzyme-Mimicking Activity to Enhance Lateral Flow Immunoassay Sensitivity

Lateral flow immunochromatography (LFIA) with gold nanoparticles (AuNPs) is widely used in the biomedical field as a rapid and simple in vitro detection technique. However, the conventional AuNP-LFIA has limitations in sensitivity and detection range. In this study, nonprecious metal iron-based bimetallic FeWO4 nanomaterials with convenient and excellent enzyme-mimetic catalytic activities were synthesized by a one-pot hydrothermal method. Here, FeWO4 nanomaterials were combined with C-reactive protein (CRP) detection antibodies to form a novel signal-enhancing probe for the analysis of CRP. The probe further achieves significant signal amplification by catalyzing the oxidation reaction of 3-amino-9-ethylcarbazole in the LFIA assay, thereby improving the sensitivity and accuracy of the assay. The application of FeWO4-based LFIA improved the limit of detection of CRP to 19.38 ng/mL after catalytic amplification, which is approximately 30-fold lower than that of the conventional AuNP-LFIA method. In addition, the method demonstrated good stability and reproducibility, providing a promising and prospective strategy for the early diagnosis of inflammatory diseases.

Seeding Janus Zn-Fe Diatomic Pairs on a Hollow Nanobox for Potent Catalytic Therapy

Dual atomic nanozymes (DAzymes) are promising for applications in the field of tumor catalytic therapy. Here, integrating with ultrasmall Fe5C2 nanoclusters, asymmetric coordination featuring Janus Zn-Fe dual-atom sites with an O2N2-Fe-Zn-N4 moiety embedded in a carbon vacancy-engineered hollow nanobox (Janus ZnFe DAs-Fe5C2) was elaborately developed. Theoretical calculation revealed that the synergistic effects of Zn centers acting as both adsorption and active sites, oxygen-heteroatom doping, carbon vacancy, and Fe5C2 nanoclusters jointly downshifted the d-band center of Fe 3d orbitals, optimizing the desorption behaviors of intermediates *OH, thereby significantly promoting catalytic activity. Upon 1064 nm laser irradiation, Janus ZnFe DAs-Fe5C2 with superior photothermal conversion efficiency (η = 62.5%) showed thermal-augmented catalytic therapy. Fascinatingly, Janus ZnFe DAs-Fe5C2 with multienzymatic properties can suppress the expression of glutathione peroxidase 4 and accelerate the accumulation of lipid peroxides, through which ferroptosis is triggered. Overall, tannin-involved asymmetric Janus ZnFe DAs-Fe5C2 will inspire more inventions of biodegradable DAzymes for tumor therapy application.

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

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

Cu-MoOx-based nanozyme with enhanced peroxidase like activity for quinolone antibiotics detection

The abuse of antibiotics has seriously threatened human health and living environment. Nevertheless, the detection of quinolones is currently mainly performed by high-cost and cumbersome means, such as High-Performance Liquid Chromatography (HPLC). Herein, we reported a novel method based on copper-doped MoOx nanoparticles (Cu-MoOx NPs) with peroxidase-like enhancement activity for the easy preparation, sensitive and rapid visualization of quinolone detection. Cu-MoOx NPs can make the chromogenic substrate 3,3',5,5'-Tetramethylbenzidine (TMB) change from colorless to blue. Moreover, the addition of quantitative quinolone antibiotics can significantly accelerate the TMB oxidation reaction. Based on this phenomenon, a colorimetric method for detecting quinolone antibiotics was established with a good linear relationship ranging from 1 × 10-6 M to 1.3 × 10-4 M, and the detection limit was 0.310 μM for ciprofloxacin (CIP) and 0.520 μM for levofloxacin (LVFX). Furthermore, the mechanism was also explored, and the results showed that the peroxidase-like activity of Cu-MoOx NPs was probably derived from the generated OH, 1O2, oxygen vacancies and partially reduced Cu+, and on the other hand was derived from quinolone antibiotics and nanozymes electrostatic interaction between them.

Nanozymes as Antibacterial Agents: New Concerns in Design and Enhancement Strategies

Nanozymes exhibiting natural enzyme-mimicking catalytic activities as antibacterial agents present several advantages, including high stability, low cost, broad-spectrum antibacterial activity, ease of preparation and storage, and minimal bacterial resistance. Consequently, they have attracted significant attention in recent years. However, the rapid expansion of antimicrobial nanozyme research has resulted in pioneering reviews that do not comprehensively address emerging concerns and enhancement strategies within this field. This paper first summarizes the factors influencing the intrinsic activity of nanozymes; subsequently, we outline new research considerations for designing antibacterial nanozymes with enhanced functionality and biosafety features such as degradable, imageable, targeted, and bacterial-binding nanozymes as well as those capable of selectively targeting pathogenic bacteria while sparing normal cells and probiotics. Furthermore, we review novel enhancement strategies involving external physical stimuli (light or ultrasound), the introduction of extrinsic small molecules, and self-supplying H2O2 to enhance the activity of antibacterial nanozymes under physiological conditions characterized by low concentrations of H2O2 and O2. Additionally, we present non-redox nanozymes that operate independently of highly toxic reactive oxygen species (ROS) alongside those designed to combat less common pathogenic bacteria. Finally, we discuss current issues, challenges faced in the field, and future prospects for antibacterial nanozymes.

Multi-Enzyme Mimetic MoCu Dual-Atom Nanozyme Triggering Oxidative Stress Cascade Amplification for High-Efficiency Synergistic Cancer Therapy

Single-atom nanozymes (SAzymes) with ultrahigh atom utilization efficiency have been extensively applied in reactive oxygen species (ROS)-mediated cancer therapy. However, the high energy barriers of reaction intermediates on single-atom sites and the overexpressed antioxidants in the tumor microenvironment restrict the amplification of tumor oxidative stress, resulting in unsatisfactory therapeutic efficacy. Herein, we report a multi-enzyme mimetic MoCu dual-atom nanozyme (MoCu DAzyme) with various catalytic active sites, which exhibits peroxidase, oxidase, glutathione (GSH) oxidase, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase mimicking activities. Compared with Mo SAzyme, the introduction of Cu atoms, formation of dual-atom sites, and synergetic catalytic effects among various active sites enhance substrate adsorption and reduce the energy barrier, thereby endowing MoCu DAzyme with stronger catalytic activities. Benefiting from the above enzyme-like activities, MoCu DAzyme can not only generate multiple ROS, but also deplete GSH and block its regeneration to trigger the cascade amplification of oxidative stress. Additionally, the strong optical absorption in the near-infrared II bio-window endows MoCu DAzyme with remarkable photothermal conversion performance. Consequently, MoCu DAzyme achieves high-efficiency synergistic cancer treatment incorporating collaborative catalytic therapy and photothermal therapy. This work will advance the therapeutic applications of DAzymes and provide valuable insights for nanocatalytic cancer therapy.

Intelligent Pyroptosis Inducer for Precise and Augmented Tumor Therapy Through Specific Activation Pyroptosis in Tumor

Pyroptosis inducer, a powerful anti-tumor agent that causes obvious programmed cell death and immune stimulation, has been challenged to trigger specific pyroptotic tumor cell death while keeping pyroptosis silence in normal cells. Here, an intelligent inducer is reported that acts as a reactive oxygen species (ROS) scavenger in normal cells to keep pyroptosis silence, while serving as ROS generator to induce obvious pyroptotic tumor cells death dependent on high hydrogen peroxide levels and near-infrared laser irradiation. This switchable activity ensures this inducer to precisely kill the tumor cells with augmented immunogenicity while causing minimal damage to normal cells. Moreover, the catalase-like activity endows this inducer to overcome limitation of tumor hypoxia on ROS generation and show significant pyroptosis activation, further initiating the immune response to inhibit the tumor metastases in vivo. This study provides valuable insights into design new pyroptosis inducer with controllable pyroptosis activity to specifically induce programmed tumor cell pyroptosis for precise and augmented tumor therapy with minimal side effects.

An electrochemiluminescence biosensor based on silver-cysteine nanorod as an emitter and AgNP-decorated FeMoOν as a signal amplifier for sensitive detection of heart-type fatty acid binding protein

An electrochemiluminescence (ECL) immunosensor was developed for the highly sensitive and specific detection of heart-type fatty acid binding protein (H-FABP) and the rapid diagnosis of acute myocardial infarction (AMI). H-FABP is a biomarker that is highly specific to cardiac tissue and is associated with a range of cardiac diseases. Following myocardial injury, the rate of increase in H-FABP levels is greater than that observed for myoglobin and troponin. Therefore, the measurement of H-FABP is crucial for the early exclusion of AMI. Silver-cysteine nanorod (AgCysNR), which served as the ECL emitter, was produced with a one-step, green, simple, template-free aqueous phase method. The surfaces of AgCysNR displayed many amino and carboxyl groups that were connected to a large number of a secondary H-FABP-specific antibody. Ferrum-doped molybdenum oxide (FeMoOν), with a large specific surface area, was richly decorated with silver nanoparticle (AgNP), which increased the interfacial electron transfer rate of FeMoOν. The AgNP was used as a co-reaction accelerator to promote persulfate to produce more sulfate anion radical and then enhance the ECL intensity of AgCysNR. The linear range of the ECL immunosensor was 10 fg/mL to 100 ng/mL, and the detection limit was 2.3 fg/mL (signal/noise = 3). The sensor was determined to be stable, repeatable, and reproducible, and the method achieved recoveries of 101.0 to 102.6% with relative standard deviations of 1.4 to 2.0%. This immunosensor represents a promising tool for the early diagnosis of AMI.

Copper-cobalt peroxide nanoparticles: a biomimetic cascade reaction for enhanced Fenton-like therapy at physiologically relevant pH

Traditional Fenton-like reactions, commonly employed in chemodynamic therapy (CDT) for cancer treatment, face limitations due to the mildly acidic tumor microenvironment (TME) and scarce H2O2 availability. Aiming to overcome these hurdles, we report herein the preparation of copper-cobalt peroxide (CCp) nanoparticles, a novel catalyst that enables a pH-activated, self-supplying H2O2-mediated cascade reaction. In the slightly acidic TME (pH 6.5-7.0), CCp nanoparticles degrade, generating H2O2in situ. This intrinsic H2O2 production eliminates the need for external H2O2 sources and enables activation in a significantly higher pH range. Simultaneously, released Cu and Co ions, primarily in lower oxidation states, synergistically drive a catalytic loop for sustained hydroxyl radical (˙OH) production. The non-ferrous bimetallic approach exhibits exquisite pH sensitivity and self-sufficiency, surpassing traditional Fenton reactions. Comparative studies highlight CCp's superior performance against copper-based bimetallic peroxides containing Fe and Ce, confirming the synergistic power of Cu-Co pairing. In vitro experiments demonstrate that the synthesized CCp-NPs exhibit greater toxicity toward breast cancer cells (4T1) than towards non-cancerous cells, showcasing their therapeutic potential. Furthermore, CCp-NPs outperform other nanoparticles in inhibiting cancer cell proliferation, colony formation, and migration. Density Functional Theory (DFT) calculations suggest that Co doping enhances CCp's ability to participate in Fenton reactions. Overall, this work is pioneering in relation to the design of a new class of smart nanoparticles for CDT. The combination of self-generated H2O2, high pH activation, and synergistic metal effects in CCp opens the door for next-generation cancer theranostic nanoparticles with unprecedented efficiency and precision, minimizing side effects.

Copper-based metal-organic framework co-loaded doxorubicin and curcumin for anti-cancer with synergistic apoptosis and ferroptosis therapy

The combination of chemotherapy and ferroptosis therapy can greatly improve the efficiency of tumor treatment. However, ferroptosis-based therapy is limited by the unsatisfactory Fenton activity and insufficient H2O2 supply in tumor cells. In this work, a nano-drug delivery system Cur@DOX@MOF-199 NPs was constructed to combine ferroptosis and apoptosis by loading curcumin (Cur) and doxorubicin (DOX) based on the copper-based organic framework MOF-199. Cur@DOX@MOF-199 NPs decompose quickly by glutathione (GSH), releasing Cu2+, DOX and Cur. Cu2+ can deplete GSH while also being reduced to Cu+; DOX can induce apoptosis and simultaneously boost H2O2 production. Moreover, Cur enhanced the expression of intracellular heme oxygenase-1 (HO-1), for decomposing heme and releasing Fe2+, which further combined with Cu+ to catalyze H2O2 for hydroxyl radical (OH) generation, leading to the accumulation of lipid peroxide and ferroptosis. As a result, Cur@DOX@MOF-199 NPs exhibited significantly enhanced antitumor efficacy in MCF-7 tumor-bearing mouse model, suggesting this nano formulation is an excellent synergetic pathway for apoptosis and ferroptosis.

Engineering Strain-Defects to Enhance Enzymatic Therapy and Induce Ferroptosis

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

Nanomaterial-based regulation of redox metabolism for enhancing cancer therapy

Altered redox metabolism is one of the hallmarks of tumor cells, which not only contributes to tumor proliferation, metastasis, and immune evasion, but also has great relevance to therapeutic resistance. Therefore, regulation of redox metabolism of tumor cells has been proposed as an attractive therapeutic strategy to inhibit tumor growth and reverse therapeutic resistance. In this respect, nanomedicines have exhibited significant therapeutic advantages as intensively reported in recent studies. In this review, we would like to summarize the latest advances in nanomaterial-assisted strategies for redox metabolic regulation therapy, with a focus on the regulation of redox metabolism-related metabolite levels, enzyme activity, and signaling pathways. In the end, future expectations and challenges of such emerging strategies have been discussed, hoping to enlighten and promote their further development for meeting the various demands of advanced cancer therapies. It is highly expected that these therapeutic strategies based on redox metabolism regulation will play a more important role in the field of nanomedicine.

Photothermally Reinforced Nanozyme Remodeling Tumor Microenvironment of Redox and Metabolic Homeostasis to Enhance Ferroptosis in Tumor Therapy

The acidity and high GSH level in the tumor microenvironment (TME) greatly limit the antitumor activity of nanozymes. Thus, enhancing nanozymes' activity is fundamentally challenging in tumor therapy. Although the combination of photothermal therapy (PTT) and nanozymes can enhance the catalytic activity, cancer cells will overexpress heat shock proteins (HSPs) at high temperature, aggravating the heat resistance of tumor cells, which in turn compromises the outcome of chemodynamic therapy. Herein, we propose an iron-doped metal-organic framework nanozyme (IB@Fe-ZIF8@PDFA) that can be activated under the weak acidity and high level of GSH, demonstrating the activities of GSH oxidation (GSH-OXD), peroxidase (POD), and NADH oxidase (NADH-OXD). Under laser irradiation, it displays photothermal-enhanced multienzyme activities to simultaneously eliminate tumors and inhibit tumor metastasis. While consuming endogenous GSH, IB@Fe-ZIF8@PDFA promotes the decomposition of H2O2 into ·OH, enhancing ferroptosis in tumor cells. Surprisingly, IB@Fe-ZIF8@PDFA nanozyme can oxide NADH and subsequently limit the ATP supply, reducing the expression of HSPs and significantly weakening the heat resistance of tumor cells during PTT. Meanwhile, H2O2 is generated during this procedure, which can endogenously replenish the consumed H2O2. Thus, this IB@Fe-ZIF8@PDFA nanozyme constitutes a self-cascading platform to consume GSH and NADH, endogenously replenish the H2O2 and continuously generate ·OH to facilitate ferroptosis by disrupting the redox and metabolic homeostasis in tumor cells, achieving tumor elimination and tumor metastasis inhibition.

Nanozymes: a bibliometrics review

As novel multifunctional materials that merge enzyme-like capabilities with the distinctive traits of nanomaterials, nanozymes have made significant strides in interdisciplinary research areas spanning materials science, bioscience, and beyond. This article, for the first time, employed bibliometric methods to conduct an in-depth statistical analysis of the global nanozymes research and demonstrate research progress, hotspots and trends. Drawing on data from the Web of Science Core Collection database, we comprehensively retrieved the publications from 2004 to 2024. The burgeoning interest in nanozymes research across various nations indicated a growing and widespread trend. This article further systematically elaborated the enzyme-like activities, matrix, multifunctional properties, catalytic mechanisms and various applications of nanozymes, and the field encounters challenges. Despite notable progress, and requires deeper exploration guide the future research directions. This field harbors broad potential for future developments, promising to impact various aspects of technology and society.

Tumor Microenvironment Activated Cu Crosslinked Near-Infrared Sonosensitizers for Visualized Cuproptosis-Enhanced Sonodynamic Cancer Immunotherapy

Reactive oxygen species (ROS)-mediated sonodynamic therapy (SDT) holds increasing potential in treating deep-seated tumor owing to the high tissue-penetration depth. However, the inevitable accumulation of sonosensitizers in normal tissues not only make it difficult to realize the in situ SDT, but also induces sonodynamic effects in normal tissues. Herein, this work reports the passivation and selective activation strategies for the sonodynamic and near-infrared (NIR) imaging performances of an intelligent antitumor theranostic platform termed Cu-IR783 nanoparticles (NPs). Owing to the ruptured coordination bond between IR783 with Cu ions by responding to tumor microenvironment (TME), the selective activation of IR783 only occurred in tumor tissues to achieve the visualized in-situ SDT. The tumor-specific released Cu ions not only realized the cascade amplification of ROS generation through Cu+-mediated Fenton-like reaction, but also triggered cuproptosis through Cu+-induced DLAT oligomerization and mitochondrial dysfunction. More importantly, the immunosuppressive TME can be reversed by the greatly enhanced ROS levels and high-efficiency cuproptosis, ultimately inducing immunogenic cell death that promotes robust systemic immune responses for the eradication of primary tumors and suppression of distant tumors. This work provides a distinct paradigm of the integration of SDT, CDT, and cuproptosis in a controlled manner to achieve visualized in-situ antitumor therapy.

In Situ Defect Engineering of Fe-MIL for Self-Enhanced Peroxidase-Like Activity

Defect engineering is an effective strategy to enhance the enzyme-like activity of nanozymes. However, previous efforts have primarily focused on introducing defects via de novo synthesis and post-synthetic treatment, overlooking the dynamic evolution of defects during the catalytic process involving highly reactive oxygen species. Herein, a defect-engineered metal-organic framework (MOF) nanozyme with mixed linkers is reported. Over twofold peroxidase (POD)-like activity enhancement compared with unmodified nanozyme highlights the critical role of in situ defect formation in enhancing the catalytic performance of nanozyme. Experimental results reveal that highly active hydroxyl radical (•OH) generated in the catalytic process etches the 2,5-dihydroxyterephthalic acid ligands, contributing to electronic structure modulation of metal sites and enlarged pore sizes in the framework. The self-enhanced POD-like activity induced by in situ defect engineering promotes the generation of •OH, holding promise in colorimetric sensing for detecting dichlorvos. Utilizing smartphone photography for RGB value extraction, the resultant sensing platform achieves the detection for dichlorvos ranging from 5 to 300 ng mL-1 with a low detection limit of 2.06 ng mL-1. This pioneering work in creating in situ defects in MOFs to improve catalytic activity offers a novel perspective on traditional defect engineering.

Tailoring metal oxide nanozymes for biomedical applications: trends, limitations, and perceptions

Nanomaterials with enzyme-like properties are known as 'nanozymes'. Nanozymes are preferred over natural enzymes due to their nanoscale characteristics and ease of tailoring of their physicochemical properties such as size, structure, composition, surface chemistry, crystal planes, oxygen vacancy, and surface valence state. Interestingly, nanozymes can be precisely controlled to improve their catalytic ability, stability, and specificity which is unattainable by natural enzymes. Therefore, tailor-made nanozymes are being favored over natural enzymes for a range of potential applications and better prospects. In this context, metal oxide nanoparticles with nanozyme-mimicking characteristics are exclusively being used in biomedical sectors and opening new avenues for future nanomedicine. Realising the importance of this emerging area, here, we discuss the mechanistic actions of metal oxide nanozymes along with their key characteristics which affect their enzymatic actions. Further, in this critical review, the recent progress towards the development of point-of-care (POC) diagnostic devices, cancer therapy, drug delivery, advanced antimicrobials/antibiofilm, dental caries, neurodegenerative diseases, and wound healing potential of metal oxide nanozymes is deliberated. The advantages of employing metal oxide nanozymes, their potential limitations in terms of nanotoxicity, and possible prospects for biomedical applications are also discussed with future recommendations.

Valence-engineered catalysis-selectivity regulation of molybdenum oxide nanozyme for acute kidney injury therapy and post-cure assessment

The optimization of the enzyme-like catalytic selectivity of nanozymes for specific reactive oxygen species (ROS)-related applications is significant, and meanwhile the real-time monitoring of ROS is really crucial for tracking the therapeutic process. Herein, we present a mild oxidation valence-engineering strategy to modulate the valence states of Mo in Pluronic F127-coated MoO3-x nanozymes (denoted as MF-x, x: oxidation time) in a controlled manner aiming to improve their specificity of H2O2-associated catalytic reactions for specific therapy and monitoring of ROS-related diseases. Experimentally, MF-0 (Mo average valence 4.64) and MF-10 (Mo average valence 5.68) exhibit exclusively optimal catalase (CAT)- or peroxidase (POD)-like activity, respectively. Density functional theory (DFT) calculations verify the most favorable reaction path for both MF-0- and MF-10-catalyzed reaction processes based on free energy diagram and electronic structure analysis, disclosing the mechanism of the H2O2 activation pathway on the Mo-based nanozymes. Furthermore, MF-0 poses a strong potential in acute kidney injury (AKI) treatment, achieving excellent therapeutic outcomes in vitro and in vivo. Notably, the ROS-responsive photoacoustic imaging (PAI) signal of MF-0 during treatment guarantees real-time monitoring of the therapeutic effect and post-cure assessment in vivo, providing a highly desirable non-invasive diagnostic approach for ROS-related diseases.

Regulating Manganese-Site Electronic Structure via Reconstituting Nitrogen Coordination for Efficient Non-Oxygen-Dependent Sonocatalytic Therapy against Orthotopic Breast Cancer

Sonocatalytic therapy (SCT) has emerged as a promising noninvasive modality for tumor treatment but is hindered by the insufficient generation of ultrasound-induced reactive oxygen species (ROS) and the hypoxic tumor microenvironments. Herein, we fabricated a carbon nanoframe-confined N-coordinated manganese single-atom sonocatalyst with a five-coordinated structure (MnN5 SA/CNF) using a phthalocyanine-mediated pyrolysis strategy. The precise coordination structure was identified by synchrotron X-ray absorption fine structure analyses. The MnN5 SA/CNF exhibits superior and nonoxygen-dependent sonocatalytic activity owing to the optimized coordination structure and cavitation effect enhanced by defects. Additionally, density functional theory studies reveal that the five-coordination structure downshifts the d-band center of Mn from -0.547 to -0.829 eV and enhances the desorption capacity for oxygen-containing intermediates, thus accelerating the catalytic process. Finally, the as-synthesized MnN5 SA/CNF demonstrates a significantly enhanced antitumor effect through mitochondrial apoptosis in an orthotopic breast cancer mouse model. This work explores the potential of SAzymes-supported biomedical interventions by leveraging enzymatic activity with sonocatalytic properties.

Doping-Engineered Piezoelectric Ultrathin Nanosheets for Synergistically Piezo-Chemocatalytic Antitumor and Antibacterial Therapies Against Cutaneous Melanoma

The post-surgical melanoma recurrence and wound infections have persistently troubled clinical management. Piezocatalytic therapy features high efficiency in generating reactive oxygen species (ROS) for tumor therapy, but it faces limitations in piezoelectricity and redox-active site availability. Herein, Fe-doped ultrathin Bi4Ti3O12 nanosheets (designated as Fe-UBTO NSs) with synergistically piezo-chemocatalytic activity are engineered for antitumor and antibacterial treatment against cutaneous melanoma. The doping-engineered strategy induces oxygen vacancies and lattice distortions in Fe-UBTO NSs, which narrows bandgap to enhance piezocatalytic 1O2 and H2O2 generation by improving the electron-hole pairs separation, hindering their recombination, and increasing oxygen adsorption. Moreover, Fe doping establishes a piezo-chemocatalytic system, in which the piezocatalysis enables the self-supply of H2O2 and expedites electron transfer in Fenton reactions, inducing increased ·OH production. Besides, the atomic-level thickness and expanded surface area enhance the sensitivity to ultrasound stimuli and expose more redox-active sites, augmenting the piezo-chemocatalytic efficiency, and ultimately leading to abundant ROS generation. The Fe-UBTO-mediated piezo-chemocatalytic therapy causes intracellular oxidative stress, triggering apoptosis and excessive autophagy of tumor cells. Moreover, this strategy accelerates wound healing by facilitating sterilization, angiogenesis, and collagen deposition. This work provides distinct options to develop doping-engineered ultrathin nanosheets with augmented piezo-chemocatalytic activity for postoperative management of cutaneous melanoma.

Photothermal Catalytic Reduction and Bone Tissue Engineering Towards a Three-in-One Therapy Strategy for Osteosarcoma

Osteosarcoma is one of the most dreadful bone neoplasms in young people, necessitating the development of innovative therapies that can effectively eliminate tumors while minimizing damage to limb function. An ideal therapeutic strategy should possess three essential capabilities: antitumor effects, tissue-protective properties, and the ability to enhance osteogenesis. In this study, self-assembled Ce-substituted molybdenum blue (CMB) nanowheel crystals are synthesized and loaded onto 3D-printed bioactive glass (CMB@BG) scaffolds to develop a unique three-in-one treatment approach for osteosarcoma. The CMB@BG scaffolds exhibit outstanding photothermally derived tumor ablation within the near-infrared-II window due to the surface plasmon resonance properties of the CMB nanowheel crystals. Furthermore, the photothermally synergistic catalytic effect of CMB promotes the rapid scavenging of reactive oxygen species caused by excessive heat, thereby suppressing inflammation and protecting surrounding tissues. The CMB@BG scaffolds possess pro-proliferation and pro-differentiation capabilities that efficiently accelerate bone regeneration within bone defects. Altogether, the CMB@BG scaffolds that combine highly efficient tumor ablation, tissue protection based on anti-inflammatory mechanisms, and enhanced osteogenic ability are likely to be a point-to-point solution for the comprehensive therapeutic needs of osteosarcoma.

Harnessing Metal-Organic Frameworks for NIR-II Light-Driven Multiphoton Photocatalytic Water Splitting in Hydrogen Therapy

The construction of near-infrared (NIR) light-activated hydrogen-producing materials that enable the controlled generation and high-concentration release of hydrogen molecules in deep tumor tissues and enhance the effects of hydrogen therapy holds significant scientific importance. To address the key technical challenge of low-efficiency oxidation-reduction reactions for narrow-bandgap photocatalytic materials, this work proposes an innovative approach for the controllable fabrication of multiphoton photocatalytic materials to overcome the limitations imposed by traditional near-infrared photocatalysts with "narrow-bandgap" constraints. Herein, an NIR-responsive multiphoton photocatalyst, ZrTc-Co, is developed by utilizing a post-synthetic coordination modification strategy to introduce hydrogenation active site CoII into a multiphoton responsive MOF (ZrTc). The results reveal that with the introduction of the CoII site, electron-hole recombination can be efficiently suppressed, thus promoting the efficiency of hydrogen evolution reaction. In addition, the integration of CoII can effectively enhance charge transfer and improve static hyperpolarizability, which endows ZrTc-Co with excellent multiphoton absorption. Moreover, hyaluronic acid modification endows ZrTc-Co with cancer cell-specific targeting characteristics, laying the foundation for tumor-specific elimination. Collectively, the proposed findings present a strategy for constructing NIR-II light-mediated hydrogen therapeutic agents for deep tumor elimination.

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

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

Carbon dots-supported Zn single atom nanozymes for the catalytic therapy of diabetic wounds

Diabetic wound treatment continues to be a significant clinical issue due to higher levels of oxidative stress, susceptibility to bacterial infections, and chronic inflammatory responses during healing. We rationally developed and synthesized an ultra-small carbon dots (C-dots) loaded with zinc single-atom nanozyme (Zn/C-dots) with the aim of promoting wounds healing by nanocatalytic treatment, especially targeting its complex pathological microenvironment. Zinc single atoms and C-dots form a dual catalytic system with higher enzymatic activity. Furthermore, the Zn/C-dots nanozyme effectively enters cells, accumulates at mitochondria, and removes excess ROS, protecting cells from oxidative stress damage and limiting the release of pro-inflammatory cytokines, hence reducing inflammation. Zinc can synergistically increase the antibacterial action of C-dots (the effective antibacterial rate of 100 µg/mL Zn/C-dots was above 90 %). Unlike traditional C-dots, Zn/C-dots can cause endothelial cell migration and the formation of new blood vessels. In vitro cytotoxicity, blood compatibility, and in vivo toxicity studies of Zn/C-dots show that they are biocompatible. We subsequently utilized the Zn/C-dots nanozymes to treat diabetic rats' chronic wounds for external use, combining them with ROS-responsive hydrogels to create an antioxidative system (H-Zn/C-dots). The hydrogels anchored the Zn/C-dots nanozymes to the wound, allowing for long-term treatment. The results revealed that H-Zn/C-dots can considerably reduce inflammation, accelerate angiogenesis, collagen deposition, and promote tissue remodeling at the diabetic wound site. After 14 days, the wound area had decreased to approximately 9.19 %, making it a potential treatment. STATEMENT OF SIGNIFICANCE: An ultra-small carbon dot with a zinc single-atom nanozyme was designed and manufactured. Zn/C-dots possess antibacterial, ROS-scavenging, and angiogenesis activities. In vivo, the multifunctional ROS-responsive hydrogel incorporating Zn/C-dots could speed up diabetic wound healing.