Thermal Atomization of Platinum Nanoparticles into Single Atoms: An Effective Strategy for Engineering High-Performance Nanozymes

Highly accessible Fe-N-C single-atom nanozymes with enhanced oxidase-like activity for smartphone-assisted colorimetric detection of uric acid

Fe-N-C single-atom nanozymes (SANzymes), which exhibit the properties of well-defined atomic structures and carefully controlled coordination environments, have become a hot research topic in biomedical fields. Unfortunately, the lower accessibility and intrinsic activity of the FeN4 sites severely limit their enzyme-like activity. Here, a densely exposed surface FeN4 structure was constructed on layered nitrogen-doped hierarchical porous carbon support through two steps of pyrolysis strategy. Using a honeycomb porous carbon support, the Fe-N-C catalyst boasted a high specific surface area with numerous Fe anchoring sites and was equipped with efficiently accessible active FeN4 structures. The Fe edge effect could modulate the electronic structure of individual Fe atoms, thereby boosting the intrinsic oxidase-like activity of the FeN4 molecules. As a result, Fe-N-C SANzymes were efficiently able to catalyze O2 with 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate, achieving higher catalytic kinetic values than previously reported SANzymes. The colorimetric sensor using Fe-N-C SANzymes further detected uric acid (UA) with a wide detection range and a low detection limit. Then the visual sensing of the colorimetric system allowed the smartphone to identify colors by HSV patterns and obtain quantitative analysis. Moreover, the developed Fe-N-C colorimetric method showed satisfactory results in clinical samples, and proved to be a simple-operated and reliable method for detection of UA. This work not only highlights the advantages of the rationally designed edge effect of iron single atoms, but also presents the promising applicability of single-atom nanozymes in clinical diagnosis and related fields.

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.

PtCu3 excavated rhombic dodecahedral nanocrystals with excellent peroxidase-like activity for highly sensitive colorimetric sensing of nitrite

Nanozymes have emerged as a forefront area in analytical sensing research, especially for the sensitive detection of nitrite, which is essential for human health. We synthesized PtCu3 rhombic dodecahedral nanocrystals (ERD NCs) via a two-step Cu-seeding method. TEM confirms that these NCs are consist of ultra-thin nanosheets with a thickness of approximately 2.8 nm, resulting in higher atomic utilization efficiency. Kinetic tests reveal that PtCu₃ ERD NCs exhibit excellent peroxidase-like activity. XPS valence band spectra demonstrate that the formation of the alloy causes a shift in the d-band center, which significantly facilitate the adsorption of H2O2 and its decomposition into hydroxyl radicals. Based on these findings, we have developed a colorimetric platform for the quantitative detection of nitrite. This platform can effectively detect nitrite in the concentration range of 5-500 μM in real samples, which is of great value for the detection of nitrite in food.

Covalent organic framework-based aptananozyme (COF@NH2 apt-AFM1): A novel platform for colorimetric and fluorescent aptasensing of AFM1 in milk

Nanozymes are valued for their cost-effectiveness and robustness but are often limited their lack of specificity. This study introduces a Covalent Organic Framework-based aptananozyme (COF@NH2 apt- AFM1) for label-free, dual-mode detection of Aflatoxin M1 (AFM1) in milk. The aptananozyme enables colorimetric detection by catalyzing the oxidation of 3, 3', 5, 5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2) and provides fluorescent signals for sensitive AFM1 identification. The dual-mode aptasensor achieves remarkable limits of detection (LOD) 7 pg/mL (colorimetric) and 5 pg/mL (fluorescent). Validation with High Performance Liquid Chromatography (HPLC) on milk samples showed recovery 97-99 % (colorimetric) and 96-101 % (fluorescent), confirming its stability and repeatability. Characterization of the COF and aptananozyme involved Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), UV-visible absorption spectroscopy, Fluorescence emission spectroscopy, Field emission scanning electron microscopy (FE-SEM), optical microscope images and Dynamic light scattering (DLS). This sensor demonstrates high sensitivity, accuracy and broader application potential.

Enhanced photocatalytic H2O2 production via a facile atomic diffusion strategy near tammann temperature for single atom photocatalysts

Current methods for preparing single atom catalysts (SACs) often suffer from challenges such as high synthesis temperatures, complicated procedures, and expensive equipment. In this study, a facile and universal atomic diffusion strategy near Tamman temperature (AD-TTam) was proposed for the synthesis of semiconductor supported non-noble metal SACs, denoted as M/S, where M = Fe, Ni, Cu, Al and S = ZnO, C3N4, TiO2(A), In2O3. Based on the empirical TTam (c.a. 1/2 of the melting point) phenomenon, this strategy utilized the higher atomic mobility in bulk metals near TTam to facilitate the migration of metal atoms to the support surface, thereby forming SACs at a relatively low temperature. A series of M/S SACs prepared using the AD-TTam strategy all exhibited enhanced photocatalytic H2O2 production activity. Notably, Cu/ZnO achieved an H2O2 production rate of 986.7 μmol g-1h-1 through the synergistic dual pathways of the water oxidation reaction and the oxygen reduction reaction, marking a 5.4-fold increase compared to pure ZnO. The introduction of Cu single atoms significantly improved the separation and migration of charge carriers in Cu/ZnO, thereby promoting the catalytic conversion of H2O and O2. Overall, this strategy is easily extensible at relatively low calcination temperatures and presents great potential for industrial applications.

Dual-atom nanozymes: Synthesis, characterization, catalytic mechanism and biomedical applications

Dual-atom nanozymes (DAzymes), a novel class of nanozymes featuring dual-metal atomic active centers, mimic the multi-metal synergistic mechanisms of natural enzymes to achieve superior catalytic activity compared to conventional single-atom nanozymes. Their unique dual-atom architecture not only effectively mitigates metal atom aggregation but also significantly enhances substrate adsorption capacity and catalytic efficiency through interatomic electronic coupling and spatial synergy. This structural innovation addresses critical limitations of single-atom nanozymes, including low metal loading and homogeneous active sites. This review systematically summarizes recent advancements in DAzymes: First, we elucidate their design principles and structural advantages, with a focus on precise synthesis strategies (e.g., spatial confinement, coordination stabilization) and atomic-level characterization techniques (e.g., synchrotron radiation-based X-ray absorption spectroscopy, spherical aberration-corrected electron microscopy). By unraveling structure-activity relationships, we clarify the multi-dimensional regulatory mechanisms of dual-atom systems-including coordination environments, electronic coupling, and spatial configurations-on redox enzyme-like activities such as peroxidase and superoxide dismutase mimics. Furthermore, we elaborate on their groundbreaking biomedical applications, including antibacterial and antitumor therapies via reactive oxygen species (ROS) regulation, antioxidant damage repair, and biosensing. This review aims to provide theoretical guidance for the rational design of high-performance DAzymes and to advance their translational applications in precision medicine and intelligent biomaterials.

Atomically Dispersed Metal Interfaces for Analytical Chemistry

ConspectusEngineering sensing interfaces with functional nanomaterials have aroused great interest in constructing novel analytical platforms. The good catalytic abilities and physicochemical properties allow functional nanomaterials to perform catalytic signal transductions and synergistically amplify biorecognition events for efficient target analysis. However, further boosting their catalytic performances poses grand challenges in achieving more sensitive and selective sample assays. Besides, nanomaterials with abundant atomic compositions and complex structural characteristics bring about more difficulties in understanding the underlying mechanism of signal amplification. Atomically dispersed metal catalysts (ADMCs), as an emerging class of heterogeneous catalysts, feature support-stabilized isolated metal catalytic sites, showing maximum metal utilization and a strong metal-support interfacial interaction. These unique structural characteristics are akin to those of homogeneous catalysts, which have well-defined coordination structures between metal sites with synthetic or biological ligands. By integrating the advantages of heterogeneous and homogeneous catalysts, ADMCs present superior catalytic activity and specificity relative to the nanoparticles formed by the nonuniform aggregation of active sites. ADMC-enabled sensing platforms have been demonstrated to realize advanced applications in various fields. Notably, the easily tunable coordination structures of ADMCs bring more opportunities to improve their catalytic performance, further moving toward efficient signal transduction ability. Besides, by leveraging their inherent physicochemical properties and various detection strategies, ADMC-enabled sensing interfaces not only achieve enhanced signal transductions but also show diversified output models. Such superior functions allow ADMC-enabled sensing platforms to access the goal of high-performance detection of trace targets and making significant progress in analytical chemistry.In this Account, we provide an overview of recent progress in atomically dispersed metal-involved interfaces in analytical chemistry. The engineering strategies focused on regulating metal centers, integrating multisite synergy, and tuning charge transport pathways are discussed to boost the catalytic activity and specificity of ADMCs as well as expand their multifunctionality. Combined with various transduction models, including colorimetry, electrochemistry, chemiluminescence, electrochemiluminescence, and photoelectrochemistry, ADMC-based sensors achieve efficient detection of diverse analytes. Specifically, the underlying mechanisms of signal transduction are highlighted. Finally, the perspective and challenges of the ADMC-enabled interface for analytical chemistry are further proposed. We hope that this Account will afford significant inspiration toward the design of ADMCs and the decoding of the improved sensing interfaces.

Recent Progress of Round-the-Clock Photocatalytic System in Environmental and Energy Applications: A Review

The prevailing overdependence on fossil fuels contributes to energy supply instability and pronounced price volatility. The combustion of these fuels emits considerable greenhouse gases and pollutants, further deteriorating the climate and environment. In response, Round-the-Clock Photocatalytic Systems (RTCPs) have emerged as a viable technological solution, attracting significant research interest due to their convenience, sustainability, and environmental benefits etc. which act as "photo-batteries" facilitate catalytic processes in the absence of light, offering continuous operation. Given the considerable potential of RTCPs, a timely examination of recent advancements is essential to optimize efforts. This review delineates the fundamental mechanisms of RTCPs, explores innovative strategies and current developments, and addresses the challenges of scaling up production. It aims to provide new insights and serve as a foundational reference for future research on RTCPs.

Flower-like Fe3O4@FPDA@Pt composite nanozyme for catalytic-photothermal tumor therapy

Fe3O4 nanoparticles, known for their magnetic targeting capabilities, biocompatibility, and heat generation upon light exposure, have been extensively explored for various therapeutic applications. However, Fe3O4 nanoparticles may agglomerate in the body, which could affect their therapeutic efficacy. To address this issue, researchers are exploring various surface modifications and structural designs to reduce agglomeration and enhance activity. We designed a Fe3O4@FPDA@Pt nanozyme, composed of Fe3O4 core covered with flower-like polydopamine (FPDA), and attached with platinum, for photothermal catalytic synergistic cancer therapy. The enzyme-like activity, photothermal performance, and in vitro and in vivo anticancer effects of the nanozyme were investigated. Importantly, Fe3O4@FPDA@Pt exhibited robust enzyme-like activity and photothermal performance. In addition, the flower-like structure was easily swallowed by tumor cells, which was conducive to the rapid production of toxic reactive oxygen species (ROS) and elevated heat at the tumor site. The synergy of these two mechanisms can effectively induce tumor cell death. This study demonstrated a novel and facile synthesis method for the nanozyme and highlighted its unique and advantageous structural characteristics for effective cancer treatment.

Single-atom nanozymes for enhanced electrochemical biosensing: A review

Enzyme-based electrochemical biosensors have broad and significant applications in biomedical, environmental monitoring, and food safety fields. However, the application of natural enzymes is limited due to issues such as poor stability, complex preparation, and high cost. Single-atom nanozymes (SAzymes), with their unique catalytic properties and efficient enzyme-like activities, present a promising alternative in the field of electrochemical biosensing. Compared to traditional enzymes, SAzyme offer enhanced stability and controllability, making them particularly effective in complex detection environments. This work presents the first systematic review of the progress made since 2018 in the use of SAzymes as alternatives to natural enzymes in electrochemical biosensors, and presents the latest advancements in this area. The review begins with a discussion of various enzyme-like activities of single-atom materials, including peroxidase (POD)-like, oxidase (OXD)-like, catalase (CAT)-like, and superoxide dismutase (SOD)-like activities. It then explores the advantages of SAzymes in improving the performance of electrochemical biosensors from multiple perspectives. The review also summarizes the applications of SAzyme-based electrochemical sensors for reactive oxygen species (ROS), metabolites, neurotransmitters, and other analytes, highlighting specific examples to elucidate underlying catalytic mechanisms and understand fundamental structure-performance relationships. In the final section, the challenges faced by SAzyme-based electrochemical biosensing are discussed, along with potential solutions.

Synergistic iron single/diatomic nanozyme-based colorimetric filtration valve for real-time detection and degradation of kitchen wastewater contaminants

Conventional single-atom nanozyme materials often exhibit limited enzyme-like activities and substrate specificity, making it challenging to meet the integrated demands for simultaneous detection and purification in environmental applications. In this study, we developed a novel nanozyme system featuring single/diatomic synergistic iron active sites (sdsFeN@G). sdsFeN@G exhibits superior multi-enzyme activities (POD, OXD, Laccase), outperforming natural enzymes in catalytic efficiency. Density functional theory (DFT) calculations revealed that the Fe-N four-coordination bonding shifted the d-band center of Fe closer to the Fermi level, enhancing the catalytic activity of the single/diatomic synergistic active sites. The colorimetric sensor platform integrating sdsFeN@G as the active component exhibited a detection limit as low as 0.992 μM and, leveraging its Laccase-like activity, achieved effective degradation of these antioxidants with a maximum degradation rate of 80 % for kitchen wastewater. To meet the real-time detection and purification needs in practical kitchen wastewater discharge processes, a convenient detection/purification integrated kitchen wastewater filtration valve was designed based on the sdsFeN@G nanozyme. This work advances the development of multi-enzyme active nanozyme materials, providing a promising strategy for addressing real-world environmental protection challenges.

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.

Ultrafast Carbothermal Shock Synthesis of Intermetallic Silicides with Anion-Cation Double Active Sites for Efficient Hydrogen Evolution

The exploration and elucidation of the active site of catalysts is crucial for advancing the comprehension of the catalytic mechanism and propelling the development of exceptional catalysts. Herein, it is unveiled that anionic Si and cationic Pt in platinum silicide (PtSi) intermetallic compounds, obtained by ultrafast Joule heating (PtSi JH), simultaneously function as dual active sites for the hydrogen evolution reaction (HER). Density functional theory calculations reveal that, when both Pt and Si simultaneously serve as the active sites, the Gibbs free energy of hydrogen adsorption is 0.70 eV, significantly lower than that of either Pt (1.14 eV) or Si (0.90 eV) alone. Furthermore, both Pt-H and Si-H species are monitored by in situ Raman during the HER process. Consequently, PtSi JH exhibits ultralow overpotentials of 14, 30, and 51 mV at current densities of 10, 50, and 100 mA cm-2, respectively, outperorming commercial Pt/C and Si powder. More importantly, the Joule heating method represents a versatile approach for synthesizing a range of metal silicides including RhSi, RuSix, and Pd2Si. Therefore, this work opens a new avenue for the identification of genuine active sites and explores promising metal silicide for HER electrocatalysis and beyond.

Ru single-atom nanozymes targeting ROS-ferroptosis pathways for enhanced endometrial regeneration in intrauterine adhesion therapy

Intrauterine adhesion (IUA) presents a significant challenge in gynecology, characterized by excessive fibrosis and compromised reproductive function, leading to severe infertility. Although biocompatible hydrogels integrated with stem cells offer a promising approach for IUA therapy, clinical applications remain limited. Recent studies have highlighted the role of ferroptosis and reactive oxygen species (ROS) in IUA pathogenesis, yet strategies targeting ferroptosis through antioxidant stress are underexplored. This study investigates the therapeutic effects and mechanisms of a Ru-Single-Atom Nanozyme (Ru-SAN) incorporated into chitosan hydrogel for treating IUA. Ru-SAN, which mimics the enzyme activities of catalase, superoxide dismutase, and glutathione peroxidase, effectively clears excess ROS and shows promise in treating oxidative stress-induced diseases. The results demonstrate the superior antioxidative capabilities of Ru-SAN, significantly suppressing the ROS-ferroptosis cycle at the injury site. This creates a favorable microenvironment for post-injury repair by inhibiting inflammation, enhancing mesenchymal-to-epithelial transformation, promoting angiogenesis, and polarizing M2 macrophages. Importantly, it mitigates adverse repair outcomes from inflammation and excessive collagen fiber deposition, ultimately restoring uterine glandular structures and thickness, thereby achieving the ultimate goal of restoring fertility and live birth rates. In conclusion, our study delineates a pioneering therapeutic approach leveraging the antioxidant properties of Ru-SAN to target ferroptosis, thereby offering an efficacious treatment for IUA.

Photothermally-enhanced ferroptotic-chemo therapy enabled by ZIF-derived multizyme

A multi-functional single-Fe-atom nanozyme (Fe-SAzyme) is designed, integrating the near-infrared photothermal property, the ability to carry chemoagent (doxorubicin - DOX), and nanocatalytic activities mimicking peroxidase, oxidase, and glutathione oxidase. The nanocatalytic activities act cooperatively to effectively produce cytotoxic radicals in the tumor microenvironment (TME), thereby leading to ferroptosis of cancer cells. The photothermal effect not only enhances the nanocatalytic therapy but also enables photothermal therapy. And release of DOX upon triggering by TME and the Fe-SAzyme activities enables chemotherapy to induce apoptosis of cancer cells. Such targeted and synergistic multi-modality treatment achieves complete tumor elimination without obvious side effects. Further, the underlying working mechanism is carefully revealed both theoretically and experimentally.

Triggering Synergistic Electronic Effect via Electron-Directed Transfer within PtNPs-Fe/NC Oxygen Reduction Catalyst for Zinc-Air Batteries

Rationally tuning Fe-N-C catalysts with synergistic nanoparticles for efficient oxygen reduction reaction (ORR) still remains challenging. Here, a nitrogen-doped carbon-supported bimetallic catalyst (PtNPs-Fe/NC), combining atomically dispersed Fe-N-C sites with Pt nanoparticles, is synthesized. Experimental results reveal a directional electron transfer between Pt nanoparticles and Fe sites, which induces an electron synergistic effect, effectively modulating the electron density around the Fe sites. The modulation significantly enhances the ORR catalytic activity of PtNPs-Fe/NC. As a result, PtNPs-Fe/NC displays a half-wave potential of 0.901 V (versus RHE) and a Tafel slope of 59 mV dec-1, surpassing the performance of commercial Pt/C and demonstrating accelerated reaction kinetics. In the meantime, PtNPs-Fe/NC maintains excellent durability in terms of stability as well. When assembled into liquid zinc-air batteries (ZABs), PtNPs-Fe/NC delivers a peak power density of 201.48 mW cm-2 and a specific capacity of 809 mAh g-1. Additionally, PtNPs-Fe/NC-based flexible ZABs display outstanding discharge performance and cycling stability. This work highlights the effectiveness of multiscale catalytic sites in advancing ORR catalyst performance and provides valuable insights into the construction strategies of catalysts for energy storage applications.

Targeting senescence with radioactive 223Ra/Ba SAzymes enables senolytics-unlocked One-Two punch strategy to boost anti-tumor immunotherapy

Senescent cells are characterized by a persistent cessation of their cell cycle, rendering them valuable targets for anti-tumor strategies in cancer treatment. Numerous studies have explored induced senescence as a promising approach in tumor therapy. Nevertheless, these treatments often come with drawbacks, including adverse side effects and weaker senescence-inducing effects. To address these challenges, we synthesized 223Ra/Ba single-atom nanozyme (SAzyme), wherein Ba SAzyme acts concurrently as a carrier for 223RaCl2, facilitating targeted delivery and minimizing side effects. The 223Ra/Ba SAzyme complex enhances various enzyme-mimicking functions, including catalase (CAT) and peroxidase (POD) activities. Importantly, 223Ra/Ba SAzyme induces cellular senescence and boost anti-tumor immunity. The persistent presence of a senescence-associated secretory phenotype (SASP) in the tumor microenvironment presents risks of immune suppression and tumor recurrence, which can be effectively mitigated by senolytics. As a result, 223Ra/Ba SAzyme were combined with anti-PD-L1 checkpoint blockade to achieve a one-two punch therapy, wherein 223Ra/Ba SAzyme exploits senescence followed by anti-PD-L1 therapy to eradicate senescent cells. This one-two punch strategy approach presents a straightforward and potent intervention for both primary tumors and distant tumor.

Isolated Metal Centers Activate Small Molecule Electrooxidation: Mechanisms and Applications

Electrochemical oxidation of small molecules shows great promise to substitute oxygen evolution reaction (OER) or hydrogen oxidation reaction (HOR) to enhance reaction kinetics and reduce energy consumption, as well as produce high-valued chemicals or serve as fuels. For these oxidation reactions, high-valence metal sites generated at oxidative potentials are typically considered as active sites to trigger the oxidation process of small molecules. Isolated atom site catalysts (IASCs) have been developed as an ideal system to precisely regulate the oxidation state and coordination environment of single-metal centers, and thus optimize their catalytic property. The isolated metal sites in IASCs inherently possess a positive oxidation state, and can be more readily produce homogeneous high-valence active sites under oxidative potentials than their nanoparticle counterparts. Meanwhile, IASCs merely possess the isolated metal centers but lack ensemble metal sites, which can alter the adsorption configurations of small molecules as compared with nanoparticle counterparts, and thus induce various reaction pathways and mechanisms to change product selectivity. More importantly, the construction of isolated metal centers is discovered to limit metal d-electron back donation to CO 2p* orbital and reduce the overly strong adsorption of CO on ensemble metal sites, which resolve the CO poisoning problems in most small molecules electro-oxidation reactions and thus improve catalytic stability. Based on these advantages of IASCs in the fields of electrochemical oxidation of small molecules, this review summarizes recent developments and advancements in IASCs in small molecules electro-oxidation reactions, focusing on anodic HOR in fuel cells and OER in electrolytic cells as well as their alternative reactions, such as formic acid/methanol/ethanol/glycerol/urea/5-hydroxymethylfurfural (HMF) oxidation reactions as key reactions. The catalytic merits of different oxidation reactions and the decoding of structure-activity relationships are specifically discussed to guide the precise design and structural regulation of IASCs from the perspective of a comprehensive reaction mechanism. Finally, future prospects and challenges are put forward, aiming to motivate more application possibilities for diverse functional IASCs.

Tuning Atomically Dispersed Metal Sites in Nanozymes for Sensing Applications

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

Substrate Specificity of Adenine-Cu-PO4 Nanozyme: Ascorbic Acid Oxidation and Selective Cytotoxicity

Though nanozymes are becoming promising alternatives to natural enzymes due to their superior properties, constructing nanozyme with high specificity is still a great challenge. Herein, with Cu2+ as an active site and adenine as a ligand, Adenine-Cu-PO4 is synthesized in phosphate-buffered saline. As an oxidase mimic, Adenine-Cu-PO4 could selectively catalyze oxidation of ascorbic acid (AA) to dehydroascorbic acid, but not universal substrates (3,3',5,5'-tetramethylbenzidine (TMB), 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and 2,4-dichlorophenol (2,4-DP)), small biomolecules (dopamine, glutathione, glucose, galactose), other vitamins (vitamin A acid, vitamin B1, vitamin K1) and even dithiothreitol (a common interference of AA). Such the specific AA catalytic oxidation is revealed that Adenine-Cu-PO4 selectively binds with AA through hydrogen bonds, accompanied with catalyzing AA oxidation, and concurrently O2 transferring to H2O2 via O2⋅-, further to H2O via ⋅OH. Based on the produced reactive oxygen species, with AA as a pro-oxidant, Adenine-Cu-PO4 nanozyme efficiently triggers severe intratumor oxidative stress to induce tumor cell death. This work opens a new avenue to design intrinsic nanozymes with high specificity, and also presents a promising application in the field of AA oxidation induced cancer therapy.

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.

Engineered Au@MOFs silk fibroin-based hydrogel phototherapy platform for enhanced wound healing performance

Wound bacterial infections not only impede the healing process but can also give rise to a range of serious complications, thereby posing a substantial risk to human health. Developing effective wound dressings incorporating phototherapy functionalities, specifically photothermal therapy (PTT) and photodynamic therapy (PDT), remains a critical area of research in modern wound care. Existing PTT-PDT systems often suffer from challenges such as nanoparticle aggregation and inefficient reactive oxygen species (ROS) generation, which are essential for therapeutic efficacy. This study presents a pioneering approach by combining zeolitic imidazolate framework derivatives (ZIFs) and Au NPs in a silk fibroin (SF) hydrogel for the first time. This combination not only prevents particle aggregation but also significantly enhances photothermal conversion efficiency and ROS generation capacity. The digital light processing (DLP) printability of our hydrogel allows for customized wound dressings tailored to individual patient needs, improving therapeutic efficacy. The hydrogel's effectiveness was evaluated through rigorous in vivo experiments, demonstrating enhanced antibacterial properties and accelerated wound healing. The biocompatibility of our hydrogel ensures its suitability for clinical applications, minimizing adverse reactions while promoting healing. A wound healing rate of 99.06 % represents a substantial improvement over the control groups, indicating markedly enhanced therapeutic efficacy. These findings underscore its multifunctionality in addressing infected wounds, presenting a promising strategy for facilitating the rapid healing of acute complex wounds in clinical applications.

Revolutionizing nanozymes: The synthesis, enzyme-mimicking capabilities of carbon dots, and advancements in catalytic mechanisms

Nanozymes, a revolutionary category of engineered artificial enzymes based on nanomaterials, have been developed to overcome the inherent limitations of natural enzymes, such as the high cost associated with storage and their fragility. Carbon dots (CDs) have emerged as compelling candidates for various applications due to their versatile properties. Particularly noteworthy are CDs with a range of surface functional groups that exhibit enzyme-like behavior, combining exceptional performance with catalytic capabilities. This review explores the methodologies used for synthesizing CDs with enzyme mimicking capabilities, highlighting potential avenues such as doping and hybrid nanozymes to enhance their catalytic efficacy. Moreover, a comprehensive overview of CDs that mimick the activities of various oxidoreductases-like peroxidase, catalase, oxidase/laccase, and superoxide dismutase-like is provided. The focus is on the in-depth exploration of the mechanisms, advancements and practical applications of each oxidoreductase-like function exhibited by CD nanozymes. Drawing upon these exhaustive summaries and analyses, the review identifies the prevailing challenges that hinder the seamless integration of CDs into real-world applications and offers forward-looking perspectives for future directions.

Nanozyme-based wearable biosensors for application in healthcare

Recent years have witnessed tremendous advances in wearable sensors, which play an essential role in personalized healthcare for their ability for real-time sensing and detection of human health information. Nanozymes, capable of mimicking the functions of natural enzymes and addressing their limitations, possess unique advantages such as structural stability, low cost, and ease of mass production, making them particularly beneficial for constructing recognition units in wearable biosensors. In this review, we aim to delineate the latest advancements in nanozymes for the development of wearable biosensors, focusing on key developments in nanozyme immobilization strategies, detection technologies, and biomedical applications. The review also highlights the current challenges and future perspectives. Ultimately, it aims to provide insights for future research endeavors in this rapidly evolving area.

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.

Atomically dispersed iron sites from eco-friendly microbial mycelium as highly efficient hydrogenation catalyst

Iron, one of the most abundant elements on earth and an essential element for living organisms, plays a crucial role in our daily metabolism. In the field of catalysis, the development of high-performance catalysts based on less toxic iron element is also of significant importance for green chemistry and a sustainable future. To construct Fe-based heterogeneous catalysts with excellent hydrogenation performance, precise modulation of the atomic coordination structure is a key strategy for enhancing catalytic activity. In this study, we present an in-situ coating method for applying a zeolitic imidazolate framework (ZIF) onto the surface of fungal hyphae. The asymmetric coordination structure of Fe1-N3P1 was precisely tailored by utilizing the phosphorus source from the fungus and the nitrogen source in the ZIFs. Detailed characterizations and density functional theory calculations revealed that the incorporation of ZIFs not only increased the specific surface area of catalysts, but also facilitated the dispersion of Fe2P nanoparticles into the Fe1-N3P1 center, making the lowest reaction energy barrier and resulting in the best performance for nitrobenzene hydrogenation when compared to the Fe2P nanoparticles and clusters. This research introduces a novel design concept for constructing asymmetric monoatomic configuration based on the inherent characteristics of natural microorganisms and the exogenous porous coordination polymers.

Understanding the Dynamic Evolution of Active Sites among Single Atoms, Clusters, and Nanoparticles

Catalysis remains a cornerstone of chemical research, with the active sites of catalysts being crucial for their functionality. Identifying active sites, particularly during the reaction process, is crucial for elucidating the relationship between a catalyst's structure and its catalytic property. However, the dynamic evolution of active sites within heterogeneous metal catalysts presents a substantial challenge for accurately pinpointing the real active sites. The advent of in situ and operando characterization techniques has illuminated the path toward understanding the dynamic changes of active sites, offering robust scientific evidence to support the rational design of catalysts. There is a pressing need for a comprehensive review that systematically explores the dynamic evolution among single atoms, clusters, and nanoparticles as active sites during the reaction process, utilizing in situ and operando characterization techniques. This review aims to delineate the effects of various reaction factors on dynamic evolution of active sites among single atoms, clusters, and nanoparticles. Moreover, several in situ and operando techniques are elaborated with emphases on tracking the dynamic evolution of active sites, linking them to catalytic properties. Finally, it discusses challenges and future perspectives in identifying active sites during the reaction process and advancing in situ and operando characterization techniques.

High-Throughput Screening and General Synthesis Strategy of Single-Atom Nanozymes for Oral Squamous Cell Carcinoma Therapy

Single-atom nanozymes (SAzymes), with their superior enzyme-like catalytic activity, have emerged as promising candidates for oncology therapeutics. The well-defined structures of SAzymes make them well predictable by experiences and theoretical calculation. However, the effects of metal center species and coordination environments on enzyme-like activity are variable, and screening catalytic activity by artificial experiments is challenging. High-throughput screening can rapidly select the activity center structures of SAzymes with optimal enzyme-like activity, thus their better application in tumor therapy is highly desirable. Herein, a "high-throughput screening-SAzymes structures" system is established for efficient oncology drug preparation by density functional theory for oxidase-like processes and screened the differences brought about by different metals and coordination environments. Through this screening process, SAzymes with transition metals (Mn, Fe, Co, Ni) as active centers are synthesized and then tested the multi-enzyme activities. It is found that the SAzyme with Co as the active metal center exhibited the best oxidase-like activity, and the system further showed good anti-oral squamous cell carcinoma properties both in vitro and in vivo. This study opens up a new avenue for the rational design of SAzymes in oral cancer therapy by combining computational screening and experimental validation.

Rationalizing hydrogel-integrated peroxidase-mimicking nanozymes for combating drug-resistant bacteria and colorimetric sensing

Due to the easy preparation, high stability and environmental friendliness, nanozymes are frequently used as promising substitutes to natural enzymes. However, the efficacy of nanozymes in biomedicine aspects is often hampered by their potential biotoxicity and limited bioavailability, which prompted structure adaption or carrier design to maximize nanozymes performance. Despite considerable efforts on carriers to deliver nanozymes efficiently, the systematic studies on enzyme-like activities of nanozymes related to platforms of nanozyme@carrier are sparse. Here, five types of hydrogel carriers composed by sodium alginate (SA), chitosan, gelatin, gelatin methacryloyl (GelMA), and polyacrylamide (PAM) were formed by distinct mode of polymerization to optimize the suitable carrier for peroxidase (POD)-mimic nanozyme consisted of hemin and bovine serum albumin (BSA). Among these proposed carriers, SA hydrogel emerged as the most effective carrier due to its compatible crosslinking mechanism and desirable stability for nanozyme functioning. By incorporating the POD-mimic nanozyme into the SA hydrogel, the catalytic performance of the nanozyme was effectively preserved, leading to improved antibacterial effects and superior sensing ability towards the colorimetric measurement of H2O2. Based on the rationalization of hydrogel carriers, the proposed study not only helped to understand the structure-function relationship between nanozyme and carriers, but provided an integrated nanoplatform of POD-mimic nanozyme with environmental disinfection as well as biomedical applications.

Construction of bimetallic oxy-hydroxides based on Ni(OH)2 nanosheets for sensitive non-enzymatic glucose detection via electrochemical oxidation and incorporation

Due to their ease of synthesis and large specific surface area, Ni(OH)2 nanosheets have emerged as promising electrochemical sensing materials, attracting significant attention in recent years. Herein, a series of oxy-hydroxides based on Ni(OH)2 nanosheets, including NiOx/Ni(OH)2@NF and (MNi)Ox/Ni(OH)2@NF (M = Co, Fe, or Cr), are successfully synthesized via the electrochemical oxidation and incorporation strategies. Electrochemical tests demonstrate that these Ni(OH)2-based oxy-hydroxides exhibit excellent electrochemical oxidation activity for glucose in alkaline electrolyte. Among these, (CoNi)Ox/Ni(OH)2@NF displays higher sensitivity of 3590.3 μA mM-1 cm-2 across a broad linear range of 10 μM to 1.14 mM, with a rapid current response time of less than 4 s. The superior sensing performances of (CoNi)Ox/Ni(OH)2@NF are attributed to the formation of abundant Ni3+ species and reactive-O atoms due to the electrochemical oxidation, and the synergistic effects of Co/Ni active sites resulting from the electrochemical incorporation process. In addition, the (CoNi)Ox/Ni(OH)2@NF demonstrates good stability and reproducibility for glucose sensing. This work fully leverages the significance of surface reconstruction of Ni(OH)2, providing new insights for the application of transition metal-based oxy-hydroxide materials in bio-sensing.

Substance migration in the synthesis of single-atom catalysts

Substance migration is universal and crucial in the synthesis of catalysts, which directly affects their existing form and the micro-structure of their active sites. Realizing migration during the synthesis of single-atom catalysts (SACs) is beneficial for not only increasing their metal loading capacity but also manipulating the electronic structures (coordination structure, long-range interactions, etc.) of their metal sites. This review summarizes the thermodynamics and kinetic processes involved in the synthesis of SACs to unveil the fundamental principles involved in their synthesis. For a better understanding of the effect of migration, the migration of both metal (including ions, atoms, and molecules) and nonmetal species is outlined. Moreover, we propose the research directions to guide the rational design of SACs in the future and deepen the fundamental understanding in the formation of catalysts.

Single-atom ruthenium nanozyme-induced signal amplification strategy in photoelectrochemical aptasensor for ultrasensitive detection of chloramphenicol

To develop ultrasensitive and rapid antibiotics residue detection method is crucial for ensuring food safety and protecting human health. Herein, a novel photoelectrochemical (PEC) aptasensor integrated with single-atom ruthenium (Ru) nanozyme-mediated catalytic precipitation as a valuable signal amplification strategy, have been established for ultrasensitive chloramphenicol (CAP) detection. Particularly, the exceptional peroxidase-mimicking activity of single-atom Ru nanozyme is responsible for accelerating the oxidation of 4-chloro-1-naphthol (4-CN) to produce insoluble precipitate on the electrode, which in turn causes a notable reduction in the photocurrent. Whereas, when CAP is present, the aptamer is liberated away the electrode because of its potent affinity with CAP, resulting in an elevation of the photocurrent signal, enhancing the detection sensitivity. Importantly, the signal amplification strategy combines the effective photoactive material of Au nanoparticles/CdS quantum dot/TiO2 composites, a PEC aptasensor for determination of CAP with an ultralow detection limit of 4.12 pM is achieved in a self-powered mode with great selectivity and accuracy. This work proposes a novel reasonable approach utilizing high-activity single-atom nanozyme to induce signal amplification strategy for the advancement of single-atom nanozyme in ultrasensitive PEC biosensor, and further creates new avenues for ultrasensitive detection beyond antibiotics residue.

Thermal Migration to Recover Spent Pt/C Catalyst

Recovery of spent Pt/C catalyst is a sustainable low-cost route to promote large-scale application of hydrogen fuel cells. Here, we report a thermal migration strategy to recover the spent Pt/C. In this route, the ZIF-8 is used to produce nitrogen doped porous carbon (NC) with abundant pyrimidine nitrogen sites as the new support. Subsequently, the spent Pt/C, NC, and NH4Cl etching reagent are mixed and heated at 900 °C to thermally migrate Pt from Pt/C onto NC with the help of NH4Cl etching reagent. The thermal-volatilized Pt tends to be captured by the pyrimidine nitrogen sites of NC support, thus producing the Pt clusters or 4-5 nm Pt particles. The recovered Pt/NC catalyst exhibits the highly stable oxygen reduction activities with a mass activity of 0.6 A mgPt -1 after 30000-cycle accelerated durability test.

Synergistic Co-Cu Dual-Atom Nanozyme with Promoted Catalase-like Activity for Parkinson's Disease Treatment

Neurodegenerative diseases like Parkinson's disease (PD) are intimately associated with oxidative stress due to the excessive highly reactive oxygen species (ROS), leading to the damage of dopaminergic neurons. Herein, we develop a Co-Cu dual-atom nanozyme (CoCu-DAzyme) by uniformly anchoring Co and Cu active sites onto an AlO(OH) substrate that exhibits remarkable catalase-like catalytic activity, far exceeding that of the Co or Cu single-atom counterparts. The following density functional theory calculations reveal that the Co sites efficiently enable H2O2 adsorption, while Cu sites promote charge transfer, synergistically promoting the catalytic decomposition of H2O2 into H2O and O2. Encouragingly, the developed CoCu-DAzyme notably ameliorates α-synuclein aggregation and alleviates the motor dysfunction inCaenorhabditis elegansPD models by substantively scavenging in vivo ROS. This research shows a novel therapeutic strategy for oxidative-stress-related neurodegenerative disorders by developing well-engineered nanozymes.

Bimetallic doped carbon dot nanozymes for enhanced sonodynamic and nanocatalytic therapy

Conventional inorganic semiconductors are not suitable for acting as nanozymes or sonosensitizers for in vivo therapeutic nanomedicine owing to the lack of excellent biocompatibility. Biocompatible carbon dots (CDs) exhibit a variety of biological activities due to their adjustable size and surface chemical modification; however, the simultaneous sonodynamic activity and multiple enzyme-mimicking catalytic activity of a single CD have not been reported. Herein, we report the development of bimetallic doped CDs as a high-efficiency nanozyme and sonosensitizer for enhanced sonodynamic therapy (SDT) and nanocatalytic therapy (NCT). By selecting metal-organic complexes like EDTA-FeNa as the carbon source, we ensure that the coordination environments of metal atoms are preserved throughout the low-temperature calcination process. Compared with the single metal doped CDs including Fe-CDs or Ni-CDs, the obtained Fe and Ni co-doped CDs (Fe-Ni-CDs) not only exhibit enhanced sonodynamic activity owing to the decreased bandgap, but also possess augmented dual enzyme-mimicking catalytic activities due to the synergistic effect of bimetallic ions. The Fe-Ni-CD-mediated cascade amplification of ROS generation could lead to the production of 1O2 and O2˙- through SDT, the generation of ˙OH through POD-mimicking catalytic activity, and the provision of more O2 for SDT through CAT-mimicking catalytic activity. Through the integrated multifunctionality of Fe-Ni-CDs, we successfully enhanced the effectiveness of antitumor treatment with a single drug injection and a single US irradiation for enhanced SDT and NCT. This work provides a distinct paradigm of endowing CDs with sonodynamic and multiple enzyme-mimicking catalytic activities for enhanced SDT and NCT through bimetallic ion doping.

Advanced Preparation Methods and Biomedical Applications of Single-Atom Nanozymes

Metal nanoparticles with inherent defects can harness biomolecules to catalyze reactions within living organisms, thereby accelerating the advancement of multifunctional diagnostic and therapeutic technologies. In the quest for superior catalytic efficiency and selectivity, atomically dispersed single-atom nanozymes (SANzymes) have garnered significant interest recently. This review concentrates on the development of SANzymes, addressing potential challenges such as fabrication strategies, surface engineering, and structural characteristics. Notably, we elucidate the catalytic mechanisms behind some key reactions to facilitate the biomedical application of SANzymes. The diverse biomedical uses of SANzymes including in cancer therapy, wound disinfection, biosensing, and oxidative stress cytoprotection are comprehensively summarized, revealing the link between material structure and catalytic performance. Lastly, we explore the future prospects of SANzymes in biomedical fields.

Safety Landscape of Therapeutic Nanozymes and Future Research Directions

Oxidative stress and inflammation are at the root of a multitude of diseases. Treatment of these conditions is often necessary but current standard therapies to fight excessive reactive oxygen species (ROS) and inflammation are often ineffective or complicated by substantial safety concerns. Nanozymes are emerging nanomaterials with intrinsic enzyme-like properties that hold great promise for effective cancer treatment, bacterial elimination, and anti-inflammatory/anti-oxidant therapy. While there is rapid progress in tailoring their catalytic activities as evidenced by the recent integration of single-atom catalysts (SACs) to create next-generation nanozymes with superior activity, selectivity, and stability, a better understanding and tuning of their safety profile is imperative for successful clinical translation. This review outlines the current applied safety assessment approaches and provides a comprehensive summary of the safety knowledge of therapeutic nanozymes. Overall, nanozymes so far show good in vitro and in vivo biocompatibility despite considerable differences in their composition and enzymatic activities. However, current safety investigations mostly cover a limited set of basic toxicological endpoints, which do not allow for a thorough and deep assessment. Ultimately, remaining research gaps that should be carefully addressed in future studies are highlighted, to optimize the safety profile of therapeutic nanozymes early in their pre-clinical development.

Optimizing the standardized assays for determining the catalytic activity and kinetics of peroxidase-like nanozymes

Nanozymes are nanomaterials with enzyme-like catalytic properties. They are attractive reagents because they do not have the same limitations of natural enzymes (e.g., high cost, low stability and difficult storage). To test, optimize and compare nanozymes, it is important to establish fundamental principles and systematic standards to fully characterize their catalytic performance. Our 2018 protocol describes how to characterize the catalytic activity and kinetics of peroxidase nanozymes, the most widely used type of nanozyme. This approach was based on Michaelis-Menten enzyme kinetics and is now updated to take into account the unique physicochemical properties of nanomaterials that determine the catalytic kinetics of nanozymes. The updated procedure describes how to determine the number of active sites as well as other physicochemical properties such as surface area, shape and size. It also outlines how to calculate the hydroxyl adsorption energy from the crystal structure using the density functional theory method. The calculations now incorporate these measurements and computations to better characterize the catalytic kinetics of peroxidase nanozymes that have different shapes, sizes and compositions. This updated protocol better describes the catalytic performance of nanozymes and benefits the development of nanozyme research since further nanozyme development requires precise control of activity by engineering the electronic, geometric structure and atomic configuration of the catalytic sites of nanozymes. The characterization of the catalytic activity of peroxidase nanozymes and the evaluation of their kinetics can be performed in 4 h. The procedure is suitable for users with expertise in nano- and materials technology.

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.

The mechanism of intrinsic peroxidase (POD)-like activity of attapulgite

Natural attapulgite (ATP) is a promising substitute for existing artificial nanozymes due to its intrinsic enzymatic activity. However, the active center of ATP's inherent enzymatic activity has not yet been revealed, which limits its further design and activity optimization. Studying the active center of mineral materials can be extremely challenging due to their complexity. Here, we demonstrated that Fe is the primary element in ATP responsible for peroxidase (POD)-like activity through theoretical speculation and experimental verification. More importantly, we found that the ratio of Fe2+/Fe3+ is responsible for the district POD-like activity of ATP from different regions with the same Fe content. Additionally, three facile strategies, including grinding, heat treatment, and acid treatment, were demonstrated to increase the relative Fe content and thus optimize the POD-like activity of ATP. Finally, ATP was used to detect the concentration of H2O2, enabling the detection of low concentrations (0.11-1.76 mM) of H2O2. This study serves as a novel reference for the future design and performance optimization of nanozymes that are based on ATP and clay minerals.

Development of a Zn-Based Single-Atom Nanozyme for Efficient Hydrolysis of Glycosidic Bonds

Hydrolytic enzymes are essential components in second-generation biofuel technology and food fermentation processes. Nanozymes show promise for large-scale industrial applications as replacements for natural enzymes due to their distinct advantages. However, there remains a research gap concerning glycosidase nanozymes. In this study, a Zn-based single-atom nanozyme (ZnN4-900) is developed for efficient glycosidic bond hydrolysis in an aqueous solution. The planar structure of the class-porphyrin N4 material approximatively mimicked the catalytic centers of natural enzymes, facilitating oxidase-like (OXD-like) activity and promoting glycosidic bond cleavage. Theoretical calculations show that the Zn site can act as Lewis acids, attacking the C─O bond in glycosidic bonds. Additionally, ZnN4-900 has the ability to degrade starch and produce reducing sugars that increased yeast cell biomass by 32.86% and ethanol production by 14.56%. This catalyst held promising potential for enhancing processes in ethanol brewing and starch degradation industries.

Doughnut-shaped bimetallic Cu-Zn-MOF with peroxidase-like activity for colorimetric detection of glucose and antibacterial applications

Metal-organic frameworks (MOFs), especially bimetallic MOFs, have attracted widespread attention for simulating the structure and function of natural enzymes. In this study, different morphologies of bimetallic Cu-Zn-MOF with different peroxidase (POD)-like activities were prepared by simply controlling the molar ratio of Cu2+ and Zn2+. Among them, the doughnut-shaped Cu9-Zn1-MOF exhibited the largest POD-like activity. Cu9-Zn1-MOF was combined with glucose oxidase to construct a sensitive and selective glucose colorimetric biosensor with a linear detection range of 10-300 μM and a detection limit of 7.1 μm. Furthermore, Cu9-Zn1-MOF can efficiently convert hydrogen peroxide (H2O2) into hydroxyl radicals that effectively kill both gram-negative and gram-positive bacteria at low H2O2 level. The results of this study may promote the synthesis of bimetallic MOFs and broaden their applications in the biomedical field.

Single-atom nanozymes for antibacterial applications

Bacteria have always been a thorny problem that threatens human health and food safety. Conventional antibiotic treatment often leads to the emergence of drug resistance. Therefore, the development of more effective antibacterial agents is urgently needed. Single-atom nanozymes (SAzymes) can efficiently eliminate bacteria due to their high atomic utilization, abundant active centers, and good natural enzyme mimicry, providing a potential alternative choice for antibiotics in antibacterial applications. Here, the antibacterial applications of SAzymes are reviewed and their catalytic properties are discussed from the aspects of active sites, coordination environment regulation and carrier selection. Then, the antibacterial effect of SAzymes is elaborated in combination with photothermal therapy (PTT) and sonodynamic therapy (SDT). Finally, the problems faced by SAzymes in antibacterial applications and their future development potential are proposed.

Engineering a two-dimensional metal-carbon nanozyme-based portable paper-based colorimetric chip for onsite and visual analysis of pyrophosphate

Sensitive and accurate analysis of pyrophosphate (PPi) is of great importance for preventing health hazard in environment. Nevertheless, most of sensors focus on sensitivity and selectivity, but practicality is also a significant quota. How to reconciling sensitivity, selectivity and practicability in one single sensor is desirable but remains challenging. Here, we created a novel metal-carbon nanozyme V2O5@C with two-dimensional (2D) morphology and high yet exclusive peroxidase (POD)-like activity via a glucose and NH4NO4-co-directed avenue, and further showed its application in constructing a portable and disposable paper-based analytical chip (PA-chip) for rapid, visual and onsite analysis of PPi. PPi etched V2O5 to prevent the decomposition of H2O2 into ·OH, resulting in weakened POD-like activity. In comparison with PPi deficiency, colorless TMB couldn't be oxidized into oxidized TMB with a dropped absorption at 652 nm. Therefore, obviously shallowed blue color on PA-chip surface was recorded, and demonstrated a negative relationship with PPi dosage, enabling rapid and visual detection of PPi with a limit of detection of 2.6 nM. This study demonstrated the burgeoning applications of nanozymes with POD-like activity in construction of PA-chips for PPi and will quicken the advancement of practical sensors, guaranteeing environmental safety.

The Exploration of Nanozymes for Biosensing of Pathological States Tailored to Clinical Theranostics

The nanozymes (NZs) are the artificial catalyst deployed for biosensing with their uniqueness (high robustness, surface tenability, inexpensive, and stability) for obtaining a better response/miniaturization of the varied sensors than their traditional ancestors. Nowadays, nanomaterials with their broadened scale such as metal-organic frameworks (MOFs), and metals/metal oxides are widely engaged in generating NZ-based biosensors (BS). Diverse strategies like fluorescent, colorimetric, surface-enhanced Raman scattering (SERS), and electrochemical sensing principles were implemented for signal transduction of NZs. Despite broad advantages, numerous encounters (like specificity, feasibility, stability, and issues in scale-up) are affecting the potentialities of NZs-based BS, and thus need prior attention for a promising exploration for a revolutionary outcome in advanced theranostics. This review includes different types of NZs, and the progress of numerous NZs tailored bio-sensing techniques in detecting abundant bio analytes for theranostic purposes. Further, the discussion highlighted some recent challenges along with their progressive way of possibly overcoming followed by commercial outbreaks.

Nanozymes and their biomolecular conjugates as next-generation antibacterial agents: A comprehensive review

Antimicrobial resistance (AMR), the ability of bacterial species to develop resistance against exposed antibiotics, has gained immense global attention in the past few years. Bacterial infections are serious health concerns affecting millions of people annually worldwide. Therefore, developing novel antibacterial agents that are highly effective and avoid resistance development is imperative. Among various strategies, recent developments in nanozyme technology have shown promising results as antibacterials in several antibiotic-sensitive and resistant bacterial species. Nanozymes offer several advantages over corresponding natural enzymes, such as inexpensive, stable, multifunctional, tunable catalytic properties, etc. Although the use of nanozymes as antibacterial agents has provided promising results, the specific biomolecule-conjugated nanozymes have shown further improvement in catalytic performance and associated antibacterial efficacy. The exclusive design of functional nanozymes with theranostic potential is found to simultaneously inhibit the growth and image of AMR bacterial species. This review comprehensively summarizes the history of nanozymes, their classification, biomolecules conjugated nanozyme, and their mechanism of enzyme-mimetic activity and associated antibacterial activity in antibiotic-sensitive and resistant species. The futureneeds to effectively engineer the existing or new nanozymes to curb AMR have also been discussed.

Facile construction of Mo-based nanozyme system via ZIF-8 templating with enhanced catalytic efficiency and antibacterial performance

Although Zeolitic Imidazolate Framework-8 (ZIF-8) shows significant promise in chemodynamic therapy of bacterial infections due to its large specific surface area and enzyme-like activity, it still faces a considerable gap compared to natural enzymes. The dependency on low pH and high concentrations of hydrogen peroxide ((H2O2) is a major factor limiting the clinical progress of nanozymes. Single-atom nanozymes (SA-zyme), which exhibit superior catalytic performance, are expected to overcome this limitation. In this study, we used ZIF-8 as a template to prepare structurally regular molybdenum-based single-atom nanozymes (Mo-zyme) by coordinating molybdenum atoms with nitrogen atoms within the zeolitic imidazolate framework and evaporating the zinc element at high temperatures. The cascade catalytic performance of the nanodrugs was enhanced by loading glucose oxidase (GOx) and encapsulating it with a hyaluronic acid (HA) layer to form a composite (Mo/GOx@HA). Upon contact with hyaluronidase from bacteria in infected tissues, the cascade reaction is triggered, resulting in the degradation of the HA shell, and releasing the encapsulated GOx. Once exposed, GOx catalyzes the oxidation of glucose into gluconic acid, resulting in a localized decrease in pH and continuous production of H2O2. The combination of lowered pH and increased H2O2 concentration significantly amplifies the catalytic activity of the Mo-zyme. This enhanced activity facilitates the in situ generation of hydroxyl radicals (•OH) on the bacterial surface, leading to effective and efficient bacterial eradication. Wound infection treatment has demonstrated that the as-prepared Mo/GOx@HA exhibits excellent antibacterial and anti-inflammatory activity. This work provided a promising enzymatic cascade reaction nanoplatform for the treatment of bacteria infected wounds.

Computer-aided nanodrug discovery: recent progress and future prospects

Nanodrugs, which utilise nanomaterials in disease prevention and therapy, have attracted considerable interest since their initial conceptualisation in the 1990s. Substantial efforts have been made to develop nanodrugs for overcoming the limitations of conventional drugs, such as low targeting efficacy, high dosage and toxicity, and potential drug resistance. Despite the significant progress that has been made in nanodrug discovery, the precise design or screening of nanomaterials with desired biomedical functions prior to experimentation remains a significant challenge. This is particularly the case with regard to personalised precision nanodrugs, which require the simultaneous optimisation of the structures, compositions, and surface functionalities of nanodrugs. The development of powerful computer clusters and algorithms has made it possible to overcome this challenge through in silico methods, which provide a comprehensive understanding of the medical functions of nanodrugs in relation to their physicochemical properties. In addition, machine learning techniques have been widely employed in nanodrug research, significantly accelerating the understanding of bio-nano interactions and the development of nanodrugs. This review will present a summary of the computational advances in nanodrug discovery, focusing on the understanding of how the key interfacial interactions, namely, surface adsorption, supramolecular recognition, surface catalysis, and chemical conversion, affect the therapeutic efficacy of nanodrugs. Furthermore, this review will discuss the challenges and opportunities in computer-aided nanodrug discovery, with particular emphasis on the integrated "computation + machine learning + experimentation" strategy that can potentially accelerate the discovery of precision nanodrugs.

Non-pyrolytic synthesis of laccase-like iron based single-atom nanozymes for highly efficient dual-mode colorimetric and fluorescence detection of epinephrine

Single-atom nanozymes have garnered significant attention due to their exceptional atom utilization and ability to establish well-defined structure-activity relationships. However, conventional pyrolytic synthesis methods pose challenges such as high energy consumption and random local environments at the active sites, while achieving non-pyrolytic synthesis of single-atom nanozymes remains a formidable technical hurdle. The present study focuses on the synthesis of laccase-like iron-based single-atom nanozymes (Fe-SAzymes) using a non-pyrolysis method facilitated by microwave irradiation. Under low iron loading conditions, Fe-SAzymes exhibited significantly enhanced laccase activity (12.1 U/mg), surpassing that of laccase by 24-fold. Moreover, Fe-SAzymes demonstrated efficient catalytic oxidation of epinephrine (EP), enabling its colorimetric detection. Owing to the remarkable laccase activity of Fe-SAzymes, the conventional nanozymes EP detection time was reduced from 60 min to 20 min, with an impressive low detection limit as low as 2.95 μM. In addition, an ultra-sensitive fluorescence method for EP detection was developed using the internal filter effect of EP oxidation products and CDs combined with carbon dots probe. The detection limit of fluorescence method was only 0.39 μM. Therefore, an visual, fast, and highly sensitive dual-mode EP detection strategy has great potential in the clinical diagnostic industry.