Superior peroxidase-like activities of InVO4 hollow nanocuboid assemblies for colorimetric detection of hydrogen peroxide and glucose

In this work, InVO4 hollow nanocuboid assemblies (IVHNs) with larger specific surface area were synthesized by a facile one-pot hydrothermal method, which were utilized as artificial biomimetic catalysts. In the presence of hydrogen peroxide (H2O2), the IVHNs nanozyme enchantingly displayed an extraordinary peroxidase-like performance, inducing the oxidation of the chromogenic compound 3,3',5,5'-tetramethylbenzidine (TMB) to generate a blue oxide. Kinetics analysis unequivocally demonstrated that the catalytic behavior of IVHNs conformed to the Michaelis-Menten mechanism, and ·O2- radicals played a vital role in the catalytic process according to the active species capture experiments. Given the exceptional catalytic performance of IVHNs, a colorimetric sensing platform was successfully established for rapid and accurate detection of H2O2 and glucose. The concentrations of H2O2 and glucose were positively correlated with the absorbance of TMB oxide in the linear ranges of 1-25 μM and 10-100 μM with the detection limit of 0.092 μM and 0.96 μM, respectively. Enriched by its exquisite stability, selectivity, and anti-interference ability, the colorimetric sensing system bestowed its success upon qualitative detection of H2O2 and glucose in real samples. This study not only unveils a novel nanozyme boasting remarkably efficient catalytic prowess, but also pioneers a rapid and straightforward approach for environmental analysis and clinical diagnosis.

Chitosan-platinum nanozyme-mediated ratiometric fluorescent immunosensor with dual catalytic cascades for sensitive detection of fenitrothion

Organophosphorus pesticide residues pose significant threats to food safety and environmental health, and their monitoring methods demand sensitivity and anti-interference capability. In this study, we developed a novel ratiometric fluorescent immunosensor for fenitrothion (FN) detection by employing chitosan-modified platinum nanoparticles (Ch-Pt NPs) as catalytic nanozymes. Ch-Pt NPs exhibit oxidase-mimicking activity, enabling the oxidation of ascorbic acid (AA) and o-phenylenediamine (OPD) to produce dehydroascorbic acid (DHAA) and 2,3-diaminophenazine (DAP, Em = 568 nm), respectively. Then, DHAA further reacted with the remaining OPD to generate quinoxaline derivatives (DFQ, Em = 430 nm). These two products further form ratiometric fluorescent signals. Taking AA as a breakthrough point, the dual-catalytic cascade of natural enzymes and nanozymes was achieved by the combination with the alkaline phosphatase (ALP) -based enzyme-linked immunosorbent assay (ALP-ELISA). Compared with the conventional colorimetric ELISA, the proposed sensor demonstrated a nearly 20-fold enhancement in sensitivity (detection limit: 0.48 ng/mL) and achieved satisfactory recoveries of 80.0-108.3 % in spiked samples. The ratiometric fluorescent immunosensor demonstrates outstanding performance and holds great potential for extensive applications in the field of pesticide monitoring.

A cascade nanoreactor based on metal azolate framework integrated natural enzyme for α-glucosidase activity assay and inhibitor screening

Enzyme cascades have attracted widespread attention owing to the exceptional specificity and efficient signals transduction, however, constrained by the high cost and limited stability of bio-enzymes. In this study, a novel mimic multienzyme nanoreactor (GOx@MAF-7(Fe), i.e. GMF) was developed through a one-step encapsulation of glucose oxidase (GOx) into a metal azolate framework, MAF-7(Fe). Benefiting from the synergistic effect of GOx and the exceptional peroxidase-like (POD) activity of MAF-7(Fe), GMF enabled a robust cascade catalytic reaction for colorimetric sensing. The unique structural and functional properties of MAF-7(Fe) not only facilitated efficient enzyme immobilization but also enhanced the stability of GOx, outperforming free enzymes in terms of storage and thermal tolerance. The GMF-based platform demonstrated high sensitivity and selectivity in glucose response. More importantly, by integrating α-glucosidase (α-Glu) into a three-enzyme cascade system, a colorimetric assay was successfully developed for α-Glu activity with a detection limit of 0.25 mU/mL, surpassing most existing methods. This platform was further applied for α-Glu inhibitor screening, with acarbose as a model inhibitor, and achieved precise quantification of inhibition efficiency (IC50 = 60.06 nM). This work not only establishes a versatile and efficient sensing platform for diabetes-related biomolecule detection but also pioneers a novel strategy for enzyme immobilization and multienzyme cascade construction, opening new avenues for multifunctional material design in biomedical research.

Sulfatase-mediated peroxidase-like activity: A chemiluminescence-based platform for high-throughput screening of natural inhibitors in cancer therapy

Sulfatase, traditionally known for its role in sulfate ester hydrolysis, has recently emerged as a potential player in tumor biology through its involvement in oxidative stress pathways. Here, we demonstrate for the first time that sulfatase exhibits peroxidase-like activity, catalyzing the generation of singlet oxygen (1O2) in the presence of oxygen. Based on the sulfatase-dependent 1O2 generation, the developed adamantly-enolether chemiluminescence probe QM-CF for imaging tumors of high sulfatase expression further verified the theory that sulfatase can be involved in tumor development. High-throughput screening (HTS) of natural compounds and clinical drugs identified scutellarin and sinomenine as potent sulfatase inhibitors that suppress tumor growth in mice. Mechanistic investigations revealed that these inhibitors modulate oxidative stress by downregulating MAPK and NF-κB pathways. Our findings unveil a previously unappreciated role of sulfatase in tumor-related oxidative stress and provide a promising platform for the discovery of novel sulfatase inhibitors, and advancing cancer therapeutics.

A robust metal-organic framework-based nanozyme with multienzyme-like properties for synergistic tumor therapy via efficient and sustainable Nitric oxide generation

Nitric oxide (NO)-based gas therapy represents an emerging strategy for cancer treatment, which, however, still suffers from insufficient intracellular NO production for compromised therapeutic efficiency due to limited endogenous hydrogen peroxide (H2O2) concentration and relatively slow NO generation rate. The use of metal-organic framework (MOF) with highly ordered porous structure and functional adjustability to design a multienzyme-like nanozyme provides a simple yet reliable approach for efficient and sustainable NO generation. Herein, a MOF-based nanozyme with multienzyme-like properties is constructed by depositing ultrasmall gold nanoparticles (Au NPs) and subsequently loading a NO donor, l-arginine (l-Arg) on an iron porphyrin integrated MOF, which enables efficient and sustainable NO generation for synergistic tumor therapy. Two notable merits of this design are (i) incorporation of Au NPs with glucose oxidase (GOx)-like property for effectively depleting intratumoral glucose, and simultaneously generating large amounts of H2O2, which is further utilized to initiate the effective production of NO and reactive oxygen species (ROS) by taking advantage of the peroxidase (POD)/NO synthase (NOS)-like activities of iron porphyrin, and (ii) deposition of ultrasmall Au NPs on the MOF for remarkably improving the structural stability of nanocomposites to circumvent the low catalytic efficiency associated with serious aggregation. This nanozyme achieves a high tumor inhibitory rate of 87.3 % with negligible systemic effects in a 4T1-tumor-bearing mice model by integrating NO, and ROS generation and starvation therapy with synergistic efficiency. Such an ingenious integration of multienzyme-like nanozyme and MOF paves a new way for NO-based gas therapy.

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.

Multifunctional nanozymatic biosensors: Awareness, regulation and pathogenic bacteria detection

It is estimated that approximately 700,000 fatalities occur annually due to infections attributed to various pathogens, which are capable of dissemination via multiple environmental vectors, including air, water, and soil. Consequently, there is an urgent need to enhance and refine rapid detection technologies for pathogens to prevent and control the spread of associated diseases. This review focuses on applying nanozymes in constructing biosensors, particularly their advancement in detecting pathogenic bacteria. Nanozymes, which are nanomaterials exhibiting enzyme-like activity, combine unique magnetic, optical, and electronic properties with structural diversity. This blend of characteristics makes them highly appealing for use in biocatalytic applications. Moreover, their nanoscale dimensions facilitate effective contact with pathogenic bacteria, leading to efficient detection and antibacterial effects. This article briefly summarizes the development, classification, and strategies for regulating the catalytic activity of nanozymes. It primarily focuses on recent advancements in constructing biosensors that utilize nanozymes as probes for sensitively detecting pathogenic bacteria. The discussion covers the development of various optical and electrochemical biosensors, including colorimetric, fluorescence, surface-enhanced Raman scattering (SERS), and electrochemical methods. These approaches provide a reliable solution for the sensitive detection of pathogenic bacteria. Finally, the challenges and future development directions of nanozymes in pathogen detection are discussed.

Achievements and challenges in glucose oxidase-instructed multimodal synergistic antibacterial applications

Glucose oxidase (GOx) with unique catalytic properties and inherent biocompatibility can effectively oxidize both endogenous and exogenous glucose with oxygen (O2) into gluconic acid and hydrogen peroxide (H2O2). Accordingly, the GOx-based catalytic chemistry offers new possibilities for designing and constructing multimodal synergistic antibacterial systems. The consumption of glucose permanently downregulates bacterial cell metabolism by blocking essential energy supplies, inhibiting their growth and survival. Additionally, the production of gluconic acid could downregulates the pH within the bacterial infection microenvironment, enhancing the production of hydroxyl radicals (∙OH) from H2O2 via enhanced Fenton or Fendon-like reactions and triggering the pH-responsive release of drugs. Furthermore, the generated H2O2 in situ avoids the addition of exogenous hydrogen peroxide. Therefore, it is possible to design GOx-based multimodal antibacterial synergistic therapies by combining GOx-instructed cascade reactions with other therapeutic approaches such as chemodynamic therapies (CDT), hypoxia-activated prodrugs, photosensitizers, and stimuli-responsive drug release. Such multimodal strategies are expected to exhibit better therapeutic effects than single therapeutic modes. This tutorial review highlights recent advancements in GOx-instructed multimodal synergistic antibacterial systems, focusing on design philosophy and construction strategies. Current challenges and future prospects for advancing GOx-based multimodal antibacterial synergistic therapies are discussed.

Manganese dioxide coupled metal-organic framework as mitophagy regulator alleviates periodontitis through SIRT1-FOXO3-BNIP3 signaling axis

Periodontitis is a prevalent chronic inflammatory disease characterized by alveolar bone resorption. Its progression is closely linked to oxidative stress where reactive oxygen species (ROS) generated by mitochondria exacerbate inflammation in positive feedback loops. Strategies for mitochondrial regulation hold potential for therapeutic advances. Metal-organic frameworks (MOFs) have shown promise as nanozymes for ROS scavenging. However, inability to directly regulate cellular processes to prevent further ROS production from damaged mitochondria during persistent inflammation makes MOFs insufficient in treating periodontitis. This study synthesizes MnO2@UiO-66(Ce) by introducing MnO2 within nanoscale mesoporous UiO-66 type MOFs. MnO2 coupled with Ce clusters in MOF channels, forms a superoxide dismutase/catalase cascade catalytic system. More importantnly, manganese endows the MOFs with bioactive effects which enhances mitophagy, facilitating the removal of damaged mitochondria, thereby restoring long-term cellular homeostasis. The results demonstrate that this synergistic antioxidant solution MnO2@UiO-66 restores mitochondrial homeostasis and osteogenic activity of periodontal ligament cells in vitro and alleviates inflammatory bone resorption in a ligature-induced periodontitis model in vivo. The SIRT1-FOXO3-BNIP3 signaling axis plays a key role in this process. This study may provide a design strategy that combines a highly efficient cascade catalytic system with long-term regulation of cellular homeostasis to combat oxidative stress in chronic inflammation.

Catalytic preference-enabled exclusive bimodal detection of methyl-paraoxon in complex food matrices using double site-synergized organophosphorus hydrolase-mimetic fluorescent nanozymes

Pesticide sensing crucially safeguards food safety and public health against environmental and health hazards. While oxidoreductase-type nanozymes (peroxidase and oxidase) have been widely used in optical pesticide detection, their susceptibility to redox interference as well as poor target specificity limits practical applications. To overcome the deficiencies, here we developed Ca2+-chelated 2-aminoterephthalic acid on nanosized ceria (Ca-ATPA@CeO2) as an organophosphorus hydrolase mimic. This design integrates stable fluorescence and dual-site catalytic activity to specifically detect methyl-paraoxon (MP) in complex food matrices. The synergy between Ca2+ (hard Lewis acid) and CeO2 creates dual active sites to catalyze MP hydrolysis into yellow p-nitrophenol (pNP), and the latter quenches nanozyme fluorescence via inner filter effect. The system enables cross-validated quantification of MP in complex samples, eliminating redox interference through target-specific catalysis. The bimodal "on" colorimetric (pNP color signal) and "off" fluorescence (nanozyme fluorescence intensity) detection achieved linear ranges within 1-200 μM, providing detection limits of 1.43 μM and 0.087 μM, respectively. Our work proposes a reliable strategy for selective MP detection that can avoid redox interference, also providing a simple yet efficient design of high-activity fluorescent hydrolase mimics with broadened applications in food safety analysis and beyond.

Two Birds with One Stone: Fe-DNA nanospheres produced via coordination-propelled self-assembly with excellent peroxidase-like property for versatile ratiometric fluorescent assay and cellular imaging

Exploring novel versatile nanozymes for multi-signal biosensing and cellular application is one of the most promising directions to meet the diversified requirements in this field. Herein, by harnessing coordination-propelled self-assembly between Fe (II) and DNAs, we prepared Fe-DNA nanospheres (Fe-DNA NSs) via a cost-effective one-step hydrothermal method, and pioneered the application of its excellent POD-mimicking property to fluorescent substrates. Initially, we investigated its enzyme-like activity using TMB as canonical colorimetric substrate and screened its catalytic oxidation effects towards different fluorescent substrates, such as T-HCl, AR, OPD and Sc, respectively. Afterwards, by virtue of the contrary fluorescent changes of Sc (decreased FI465) and OPD (increased FI562) and the cooperative effects of FRET/IFE between them, we devised the first universal Fe-DNA nanospheres-based ratiometric fluorescent (RF) platform. Taking H2O2 and glucose as model targets, two RF biosensors based on the alternative direct-nanozyme-catalysis and enzyme/nanozyme-tandem-catalysis were rationally fabricated, respectively. And we further exploited them to evaluate the quality of commercial contact lens care solution, and sensitively determine the blood glucose level of human. Moreover, corresponding cytotoxicity experiments adequately proved the superior biocompatibility of Fe-DNA NSs over most inorganic nanozymes. Furthermore, taking Cy5-labelled A20 strands as templates, we synthesized small-sized (∼60 nm) Fe-DNA fluorescent nanozyme and achieved efficient cellular delivery/imaging. This work not only offered a valid prototype for operating multi-signal-responsive nanozymatic biosensors, but also opened unique avenues for the bio-applications of nucleic acids-originated fluorescent nanozymes in cellular imaging and biotherapy.

Exploring the Subcellular Localization and Degradation of Spherical Nucleic Acids Using Fluorescence Lifetime Imaging Microscopy

Spherical nucleic acids (SNAs) are a powerful class of nucleic acids with broad applications that span from diagnostic sensors to nanoflares and gene therapeutic agents. SNAs accomplish these varied tasks by taking advantage of the programmability of nucleic acids coupled with enhanced multivalent interactions and improved cellular delivery. Nonetheless, the intracellular trafficking of SNAs remains poorly understood, as conflicting claims in the literature suggest rapid endosomal entrapment and degradation in some cases, while others suggest SNA stability and cytoplasmic escape. One of the challenges in this area is that some of the prior literature claims rely on intensity-based fluorescence measurements, which are indirect and prone to artifacts. Here, we demonstrate the use of fluorescence lifetime imaging microscopy (FLIM) as a tool to provide additional insight into the SNA intracellular fate. We specifically employ FLIM to investigate monothiol and dithiol anchored gold nanoparticle conjugates as well as phosphorothioate backbone-modified SNAs which allow us to characterize the initial stages of SNA degradation within cells. Our work shows that internalized SNAs lose up to 20% of their nucleic acids within 24 h depending on DNase II-activity and thiol-displacement in model cell lines.

Enhanced chemotherapy in thyroid carcinoma: A MnO2-silica nanoreactor activated by H2O2/GSH for hypoxia relief

Thyroid cancer is the most prevalent endocrine cancer that threats to the health of human being seriously, and characterized with resistance to various therapeutic modalities. The therapeutic efficacy of oxygen-dependent chemotherapy is hindered by hypoxia within tumor tissue heavily. Therefore, the supply of oxygen in situ is an effective strategy to improve the chemotherapeutic outcomes. The emergence of nanomedicine open an novel gate for tumor treatment, however, there is still lack of nanoplatforms for sufficient oxygen supply to improve the chemotherapeutic efficiency. In this study, MnO2 nanoenzyme was decorated onto glutathione (GSH)-sensitive mesoporous silica, and an intelligent nanoreactor was subsequently constructed by loading saikosaponin-d (SSD) into the mesopore channels and modified with folic acid. Upon targeted delivery to thyroid tumor cells, the Mn2+ hydrolyzed from nanoreactor facilitated the decomposition of endogenous H2O2 in the tumor, alleviating the hypoxic tumor microenvironment. Simultaneously, the tetrasulfide bonds of silica were cleaved by cytoplasmic L-GSH, releasing the loaded cargoes. Consequently, a remarkably enhanced chemotherapeutic effect of SSD was achieved both in vitro and in vivo. The mechanism underlying the tumor cell-killing effect was attributed to the generation of copious amounts of O2via disrupting the PI3K/Akt signaling pathway via transcriptome sequencing. The outstanding biocompatibility of the H2O2/GSH dual-sensitive Mn-based nanoreactor offered an exceptional chemotherapeutic effect against malignant tumors.

A carbon fiber modified with tin oxide/graphitic carbon nitride as an electrochemical indirect competitive immuno-sensor for ultrasensitive aflatoxin M1 detection

The importance of developing multifunctional nanomaterials for sensing technologies is increasing with the arrival of nanotechnology. In this study, we describe the introduction of novel nanoprobe electro-active material into the architecture of an electrochemical immuno-sensor. Based on the electrochemical immuno-sensor, functionalized tin oxide/graphitic carbon nitride nanocomposite (fSnO2/g-C3N4) was synthesized and then analyte specific anti-aflatoxin M1 monoclonal antibody (AFM1-ab) combined to form an electro-active nanoprobe (fSnO2/g-C3N4/AFM1-ab). First, aflatoxin M1 (AFM1) conjugated bovine serum albumin (BSA-AFM1) was electro-oxidized on the surface of carbon fiber (CF) followed by the consequent addition of nanoprobe. The formation of nanocomposite was substantiated through various characterization techniques, Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and Dynamic light scattering (DLS). Immuno-sensor fabrication was characterized via Field emission scanning electron microscopy (FE-SEM), optical microscope images, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). This immuno-sensor demonstrated good reproducibility, selectivity, specificity and sensitivity for AFM1 (LOD of 0.03 ng mL-1). Following spiking, this immuno-sensor produced good recovery values in the range of 94-96 % against real sample, such as milk. The development of sophisticated sensing methods for a range of analytes can greatly benefit from the widespread application of this innovative immuno-sensing approach.

Bovine amniotic membrane with antioxidant and anti-inflammatory properties for the repair of alkali-burned corneas

Corneal alkali burns are a common ocular emergency that can lead to blindness, marked by inflammation and delayed epithelial healing due to elevated oxidative stress in the intraocular environment. Mitigating the levels of reactive oxygen species (ROS) and the inflammatory response is essential for developing corneal repair materials. Amniotic membrane (AM) is frequently employed for ocular surface repair but faces limitations such as limited availability and rapid degradation. This study developed a crosslinked decellularized bovine amniotic membrane (CAM) with high transparency, enhanced mechanical strength, and enzyme resistance. By introducing Manganese-based carbon dots (Mn CDs), the composite (CDs@CAM) retained the physical properties of CAM meanwhile brought in the multi-enzyme activities of Mn CDs. Extensive characterizations demonstrated CDs@CAM high CAT-like activity, SOD-like activity and scavenging ability of hydroxyl radical and nitrogen radical. Furthermore, cellular and animal experiments demonstrated that the CDs@CAM possessed good biocompatibility, strong antioxidant capabilities, and anti-inflammatory effects, and thus significantly promoted corneal epithelial regeneration, inhibited neovascularization, and prevented scarring in alkali burn repair. This study offers a feasible strategy for artificial corneas and corneal disease treatment. STATEMENT OF SIGNIFICANCE: In this study, we developed a crosslinked decellularized bovine amniotic membrane (CAM) integrated with manganese-based carbon dots (Mn CDs), creating a composite material (CDs@CAM) that addressed the issue of high oxidative stress and severe inflammation in the eye caused by corneal alkali burns. Different from the conventional amniotic membrane products, CDs@CAM retains advantageous physical properties and biocompatibility of CAM while offering potent antioxidant and anti-inflammatory capabilities. We confirmed its good biocompatibility, as well as reductions in intracellular ROS levels and inflammatory responses. Importantly, in an alkali-burned cornea model, we revealed its outstanding performance in promoting corneal epithelial repair, inhibiting neovascularization, and thus preventing scarring, restoring corneal thickness and clarity to normal levels.

Multi-site orbital coupling in Ru-based high-entropy alloy-enabled hydroxyl spillover for enhanced peroxidase-like activity

Peroxidase (POD)-like nanozymes are attracting increasing attention in anti-tumor, antibacterial, disease diagnosis, and environmental applications. However, simultaneously improving the POD-like activity and stability of nanozymes remains a non-trivial challenge. Inspired by the excellent stability and multiple active sites of high-entropy alloys, we design a Ru-based (RuPtIrRhCu) high-entropy alloy nanozyme (HEAzyme) with improved catalytic activity and stability. Benefiting from the strong adsorption capacity of Ru toward hydrogen peroxide (H2O2)/hydroxyl (OH) and the collaborative effect induced by the multiple elements, an interesting "hydroxyl spillover" route is triggered on the RuPtIrRhCu HEAzymes. The efficient dissociated adsorption of H2O2 and fast transfer of adsorbed hydroxyl (*OH, * denotes the adsorbed state) is achieved, resulting in boosted POD-like activity. The POD-like activity of the HEAzyme remained unchanged for 6 months, exhibiting outstanding stability. A multi-channel colorimetric sensor array was developed to specifically identify eight biological antioxidants, especially for the chiral recognition of l-cysteine (l-Cys) and d-cysteine (d-Cys). This study not only provides an effective, multi-site collaborative mechanism for improving POD-like activity and stability but also extends the horizons and perspectives in nanozymes.

Innovations in smart enzyme biosensors: Advancing the detection of antibiotic residues in aquaculture

In aquaculture, the presence of antibiotic residues is an escalating concern that poses significant risks to human health. Establishing efficient and user-friendly detection methods for antibiotic residues has become crucial to mitigate these potential hazards. To address the limitations of traditional techniques, novel enzyme biosensors, offering high sensitivity and specificity and rapid response, has been introduced for monitoring a wide range of antibiotics in food safety applications. Herein, this paper reviews the innovations and advances of smart enzyme biosensors for the detection of up to 23 antibiotics in aquatic foods (fish, shrimp, crab, etc.) and related water samples in the last decade, focusing on biosensors' construction principles, detection performance, and potential applications. The colorimetric biosensors account for 62.5 %, and the limit of detection (LOD) reaches as low as fM levels. To our best knowledge, this is the first review to introduce the innovations and progress in smart enzyme biosensors for the detection of antibiotic residues in aquaculture, with the evolution from conventional natural enzyme-based biosensors to biosensors containing bio-recognition elements and mimic enzymes, and then the integrated mimic enzyme-based biosensors. These biosensors realized highly-sensitive and specific detection of antibiotics. Further development should focus on exploration of multifunctional and intelligent bio-sensing strategies, robust mimic enzyme-based biosensors, and biosensors based on integrated mechanism of recognition and transduction, so as to promote the techniques from lab studies into practical applications. This review serves as powerful enlightenment to inspire further enhancement of smart enzyme biosensors for monitoring antibiotics in aquaculture to ensure food safety.

Proton Driving Mechanism Revealed in Sulfur-Doped Single-Atom FeN2O2 Carbon Dots for Superior Peroxidase Activity

Heteroatom-doped single-atom nanozymes (SAEs) hold great promise as enzyme mimics, yet their catalytic mechanisms remain unclear. This study reveals that the proton driving mechanism induced by sulfur doping in single-atom FeN2O2 carbon dots (S-FeCDs) significantly enhances peroxidase (POD)-like activity. Synthesized via low-temperature carbonization, S-FeCDs exhibit FeN2O2 coordination with sulfur in the second shell, as confirmed by XAFS and AC-STEM. The POD-specific activity of S-FeCDs reached 295 U mg-1, which is 11.2-fold higher than that of sulfur-free FeCDs, with natural enzyme-like kinetics. In situ experiments, kinetic and mechanistic studies revealed that sulfur doping promotes H2O dissociation, enhances H+ adsorption, reduces the ΔG for H2O2-to-·OH conversion. DFT revealed a lowered energy barrier for the rate-determining step (2*OH → *O + *H2O) from 2.50 to 1.62 eV. In vivo, S-FeCDs demonstrated broad pH efficacy in MRSA-infected wound models, achieving near-complete healing within 7 days. The proton driving mechanism was further validated through nitro compound reduction, demonstrating accelerated N─H bond activation. This work highlights the critical role of sulfur-induced proton dynamics in enhancing SAEs performance, providing a rational strategy for designing multifunctional nanozymes in biomedical and catalytic applications.

Naked eye detection of hydrogen peroxide via curcumin functionalised gold nanoparticles

Nanozymes are a class of inorganic nanomaterials that mimic enzyme activity. Their high durability and strong catalytic performance make them effective surrogates for natural enzymes. In this study, we synthesized curcumin-stabilized gold nanoparticles, which were employed for the colorimetric detection of hydrogen peroxide (H₂O₂) using the chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB). Steady-state kinetic parameters were determined by varying the substrate concentrations. When H₂O₂ was used as the substrate, the Michaelis-Menten constant (Km) and the maximum reaction rate (Vmax) were found to be 3.10 × 10⁻³ M and 9.27 × 10⁻⁷ M/s, respectively. For TMB, the Km and Vmax values were 0.30 × 10⁻³ M and 1.80 × 10⁻⁷ M/s, respectively. The lower Km value for H₂O₂ indicates a higher affinity of the nanozyme for this substrate. The electron transfer ability of the nanozyme was further confirmed by cyclic voltammetry and impedence analysis, performed by immobilizing the gold nanoparticles on the surface of an electrode. Thus, this study presents a dual-mode method for the detection of H₂O₂ using curcumin-stabilized gold nanoparticles.

Bimetallic oxide (CoNi2O4) nanozyme as ROS independent for ascorbic acid detection with computational study

Herein, spinel CoNi2O4 nanoflowers (NFs) were successfully synthesized by a two-step hydrothermal annealing process and testified to have intrinsic enzyme mimic activities. The CoNi2O4 NFs can effectively oxidize the chromogenic substrate 3, 3', 5, 5'-tetramethylbenzidine (TMB) to ox-TMB showing catalytic behavior that follows enzyme kinetics of Michaelis-Menten equation with a low constant (Km = 0.0143 mM). Innovatively, experimental data and Density Functional Theory (DFT) calculations disclosed the stable structure and mechanism of spinal CoNi2O4NFs, which demonstrated oxidase-like activity and reactive oxygen species independence across a wide temperature range. Accordingly, a colorimetric biosensor for rapid and sensitive detection of ascorbic acid (AA) was successfully developed, displaying excellent stability, selectivity, sensitivity and low limit of detection (0.44 μM). This biosensor was applied to vitamin C capsules and fresh lemon fruit, showing favorable reproducibility and feasibility. DFT and molecular modeling (MD) calculations indicate a cobalt atom as the optimal site for catalytic conversion, while the amine group in the TMB molecule is the optimal nucleophilic attack site.

CuSeO3@f-CNFs: A superoxide nanozyme for the selective nanomolar determination of the key cardiovascular biomarker, Glutathione

Nanocomposites that mimic the characteristics of enzymes, commonly as nanozymes, can function as an efficient sensing material with high selectivity towards the targeted biological macromolecule. These nanozymes overcome of the challenges that arise when using natural enzymes as sensing material. This study presents a novel nanozyme, Copper Selenite (CuSeO3) nanoparticles mounted on f-CNF, to electrochemically determine a potential cardiovascular biomarker, Glutathione (GSH). The choice of this material is due to the well-known ability of GSH to form a complex with copper. When a Cu ion enters a healthy cell, it quickly forms a complex with GSH, which then moves to another storage molecule: either a metalloprotein or a chelator. CNF was functionalized using acid to generate functionalized-CNF to enhance biocompatibility and boost conductivity. This was done to provide many active sites for effective integration of CuSeO3 in the nanocomposite preparation. The glassy carbon electrode (GCE) surface was enhanced by introducing CuSeO3@f-CNF nanocomposite, resulting in a significant increase in the current response for GSH in comparison to prior research. CuSeO3@f-CNF/GCE sensor has shown excellent sensing properties, like enhanced stability, selectivity, sensitivity, and reproducibility, for detecting and quantifying GSH. The sensor demonstrated an extensive linear detection range from 62.5 nM to 7785.0 μM, signifying one of the most comprehensive ranges documented to date. It attained a remarkable detection limit (LOD) of 17.6 nM. The sensor's performance was further tested by analyzing genuine biological fluid samples. The nanozyme-modified GCE demonstrated exceptional electrocatalytic efficiency for GSH detection, making it extremely appropriate for real-time monitoring applications.

Exosome-Based Sensor: A Landmark of the Precision Cancer Diagnostic Era

Extracellular vesicles are nanoscale vesicles released by a diversity of cells that mediate intercellular communication by transporting an array of biomolecules. They are gaining increasing attention in cancer research due to their ability to carry specific biomarkers. This characteristic makes them potentially useful for highly sensitive, noninvasive diagnostic procedures and more precise prognostic assessments. Consequently, EVs are emerging as a transformative tool in cancer treatment, facilitating early detection and personalized medicine. Despite significant progress, clinical implementation is hindered by challenges in EV isolation, purification, and characterization. However, developing advanced biosensor technologies offers promising solutions to these obstacles. This review highlights recent progress in biosensors for EV detection and analysis, focusing on various sensing modalities including optical, electrochemical, microfluidic, nanomechanical, and biological sensors. We also explore techniques for EV isolation, characterization, and analysis, such as electron microscopy, atomic force microscopy, nanoparticle tracking analysis, and single-particle analysis. Furthermore, the review critically assesses the challenges associated with EV detection and put forward future directions, aiming to usher in a cutting-edge era of precision medicine through advanced, sensor-based, noninvasive early cancer diagnosis by detecting EV-carried biomarkers.

Electrochemiluminescent/colorimetric biosensors for ultrasensitive detection of Aβ based on CdS quantum dot-modulated HOFs-Cu2+-g-C₃N₄

In this work, we presented an electrochemiluminescent (ECL)/colorimetric biosensors for ultrasensitive detection of β-amyloid peptide (Aβ) based on hydrogen-bonded organic framework (HOFs)-Cu2+-graphitic carbon nitride (g-C3N4) nanocomposites. HOFs-Cu2+-g-C3N4 could be used both as an ECL luminescent substrate and as a nanozyme to catalyze the chromogenic reaction of 3,3',5,5'-tetramethylbenzidine (TMB). Specifically, in the ECL mode, HOFs-Cu2+-g-C3N4 were firstly loaded on the surface of the electrode. The target analyte Aβ could simultaneously bind both Cu2+ and the peptide fragment KLVFF, thereby capturing the CdS quantum dots (QDs)-KLVFF on the electrode. The CdS QDs could perform ECL resonance energy transfer with HOFs-Cu2+-g-C3N4, resulting the increase in the ECL intensity. Meanwhile, in the colorimetric mode, the aptamer loaded on the magnetic beads could specifically capture the target Aβ. HOFs-Cu2+-g-C3N4 used as the nanozyme in the TMB-H2O2 chromogenic system could be sequentially bound with the target Aβ. The convenient colorimetric detection of Aβ was achieved after magnetically separating using the functionalized magnetic beads. The concentration range of Aβ detected by ECL mode was 0.1 pM ∼ 0.1 μM with a detection limit of 0.07 pM, while the concentration range of Aβ detected by colorimetric assay was 0.1 pM ∼ 0.1 μM with a detection limit of 0.032 pM. These two different assay modes enhanced the sensitivity and reliability of the detection of Aβ and demonstrated potential applicability in the early diagnosis of Alzheimer's disease.

Recent trends and advances in single-atom nanozymes for the electrochemical and optical sensing of pesticide residues in food and water

Nowadays, single-atom nanozymes (SAzymes) and single-atom catalysts (SACs) have flourished in the field of catalysis owing to their high catalytic performance and exceptional atom utilization efficiency, thereby enhancing biosensing capabilities. In comparison to natural enzymes, SAzymes offer several advantages, including cost-effectiveness, ease of production, and robust catalytic activity, making them highly promising for biosensing applications. Notably, SAzymes demonstrate superior catalytic efficiency and selectivity compared with traditional nanozymes. In this context, this review delineates the enzyme-like characteristics of SAzymes aimed at enhancing food safety, with a focus on the primary factors that influence their catalytic efficacy. The discussion has been expanded to include the use of SAzymes for screening various pesticide residues, particularly organophosphate pesticides (OPPs), carbamates, acetamiprid, pyrethroids, and other pesticide types, which are present in agricultural food products. These applications are realized because of the exceptional properties of single-atom structures, including enhanced reaction kinetics, high active site density, and tunable electronic properties. The integration of SAzymes into sensing platforms holds great potential for the development of cost-effective, sensitive, and reliable tools for the real-time monitoring of pesticide residues. Finally, this paper highlights the current challenges and outlines potential opportunities for the advancement of SAzyme-based biosensing technologies.

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.

Synergizing Catalysis with Post-catalysis Pseudo-Iron Release by Building Dynamic Catalytic Active Sites in Diatomic Nanozymes for Boosting Cancer Therapy

Biomimetic nanozymes hold considerable promise for cancer therapy, but their therapeutic potential is often constrained by their limited catalytic activity. Here, we present a Ga/Zn diatomic nanozyme (Ga/Zn-NC) with a well-defined geometric structure and electronic configuration designed to emulate peroxidase and glutathione oxidase with exceptional catalytic activities, enabling cascade catalysis. We demonstrate that the formation of Ga-Zn metal bonding is essential for accelerating electron transfer and reducing the reaction energy barrier, thus enhancing the catalytic performance. Within the tumor microenvironment, the catalytic actions of Ga/Zn-NC induce oxidative damage and sensitize breast cancer cells to ferroptosis. Concurrently, the release of gallium from Ga/Zn-NC with "pseudo-iron" activity disrupts iron metabolism and activates a self-amplifying ferroptosis pathway, synergizing with the enzyme's catalytic activity to potentiate ferroptosis and apoptosis, thereby achieving remarkable efficacy against tumors.

Advancements in herbal medicine-based nanozymes for biomedical applications

ABSTRACT

Nanozymes are a distinct category of nanomaterials that exhibit catalytic properties resembling those of enzymes such as peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Nanozymes derived from Chinese herbal medicines exhibit the catalytic functions of their enzyme mimics, while retaining the specific medicinal properties of the herb (termed "herbzymes"). These nanozymes can be categorized into three main groups based on their method of synthesis: herb carbon dot nanozymes, polyphenol-metal nanozymes, and herb extract nanozymes. The reported catalytic activities of herbzymes include POD, SOD, CAT, and GPx. This review presents an overview of the catalytic activities and potential applications of nanozymes, introduces the novel concept of herbzymes, provides a comprehensive review of their classification and synthesis, and discusses recent advances in their biomedical applications. Furthermore, we also discuss the significance of research into herbzymes, including the primary challenges faced and future development directions.

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.

Ceria-Nanoparticle-Entangled Reticulation for Angiogenic and Therapeutic Embrocation for Multifactorial Approach to Treat Diabetic Wound

The therapeutic efficacy of a nanomedicine or a natural biomaterial can vary in different disorders due to their complex pathophysiology. A nanomedicine that is capable of not only targeting specific pathological cues through functional ligands but also optimizing the therapeutic efficacy of its components throughout the intricate pathways involved in complex disorders is highly desired. Here, ceria-nanoparticle-entangled reticulation for angiogenic and therapeutic embrocation (CERATE), composed of hyaluronic acid, levofloxacin, and the as-synthesized ceria nanoparticles is developed. CERATE is formulated in situ as a rigid nanoparticle-based network that integrates its components intimately using highly diluted concentrations, thereby augmenting the therapeutic efficiency of its individual components. The physical states of CERATE can be altered freely while retaining its integrity, by adjusting the water proportion to accommodate diverse clinical needs. This physically robust CERATE can withstand enzymatical degradation, display antibacterial activity, scavenge reactive oxygen species, and improve the migration and proliferation of fibroblasts by activating the proangiogenic factors. CERATE accelerates the repair of diabetic wounds by promoting both the angiogenesis and the synthesis of collagen. The results demonstrate the effectiveness of a multifactorial approach involving the recruitment of minimally modified biofunctional ligands and nanomaterials altogether with synergistic efficacy in treating complex disorders.

Recent progress in nanomaterial-based electrochemical biosensors for hydrogen peroxide detection & their biological applications

The electrochemical biosensor has brought a paradigm shift in the field of sensing due to its fast response and easy operability. The performance of electrochemical sensors can be modified by coupling them with various metal oxides, nanomaterials, and nanocomposites. Hydrogen peroxide is a short-lived reactive oxygen species that plays a crucial role in various physiological and biological processes. Therefore, its monitoring is of paramount importance. With this, the research fraternity has developed various nanomaterial-based superlative sensors that have enhanced the sensing performance towards H2O2 in terms of sensitivity, detection limit, and linear range. The integration of nanocomposite materials has allowed for the synergistic combination of different components, leading to improved sensor stability, selectivity, and detection limits. The precious metal alloys, metal oxides, semiconductor nanomaterials, carbon cloth, multi-walled carbon nanotubes, graphene oxide, and nanoparticles demonstrate effective catalytic performance for detecting H2O2 electrochemically. These advanced materials possess extraordinary properties and structures, rendering them highly advantageous for diverse applications. These biosensors aid in monitoring H2O2 levels secreted by MCF-7, HeLa cells, NIH-3T3, and A549 cells in real-time. Further, this type of biosensor identified alterations in H2O2 levels in the lungs, bronchoalveolar lavage fluid (BALF) of mice with pulmonary fibrosis, activated hepatic stellate cells, and the livers of mice with liver fibrosis. The current review highlights the recent advancements in compositions, morphology, limit of detection, sensitivity, biological applications, etc. properties of the electrochemical biosensors for H2O2 detection.

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

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

Interactions of metal-based nanozymes with aptamers, from the design of nanozyme to its application in aptasensor: Advances and perspectives

Nanozymes, characterized by enzyme-like activity, have been extensively used in quantitative analysis and rapid detection due to their small size, batch fabrication, and ease of modification. Researchers have combined aptamers, an emerging molecular probe, with nanozymes for biosensing to address the limited reaction specificity of nanozymes. Nanozyme aptasensors are currently experiencing significant growth, offering a promising solution to the lack of rapid detection methods across various fields. Unlike traditional nanozyme research, the development of nanozyme aptasensors is challenging as it requires the design of highly active nanozymes as well as the establishment of efficient and agile interactions between aptamers and nanozymes. Therefore, this review summarizes the active species and catalytic mechanisms of various nanozymes along with classical design options, discussing the future development of nanozyme aptasensors. It is anticipated that this review will inspire researchers in this domain, leading to the design of more enzymatically active nanozymes and advanced nanozyme aptasensors.

CoOx/CeO2@C nanopetals derived Cobalt-Cerium Prussian blue with enhanced Dual-Enzyme mimetic activity for detection of ascorbic acid in rat brain during calm/ischemic processes

In this study, we demonstrate that a highly efficient colorimetric sensor prepared from carbon-shielded Co-Ce Prussian blue analog (PBA) nanopetals (CoOx/CeO2@C) by green chemical deposition method and thermal annealing processes for detection of ascorbic acid (AA) in cerebral microdialysis fluids. The synthesized CoOx/CeO2@C showed high dual-mimetic activity, i.e., peroxidase- and catalase-like activity, and great catalytic stability. The combination of carbon film and Co-Ce PBA nanopetals (1) greatly enhances the interfacial electron transfer rate of the nanopetals due to excellent electrical conductivity of carbon, and (2) protects nanopetals from acidic chemical environments during the catalytic process, which greatly reduces loss of the catalytic activity of the cobalt-cerium (hydroxide) oxides. Based on the peroxidase-like property of CoOx/CeO2@C nanopetals, this sensor has a good linear range from 0.1 to 150 μM with a low detection limit of 0.04 μM, i.e., improved sensitivity for AA colorimetric measurement. The developed colorimetric strategy with a green synthetic pathway, catalytic stability and wide linear range confirms the monitoring of AA in brain systems during calm/ischemic processes.

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

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

Inhibition of the cGAS-STING pathway via an endogenous copper ion-responsive covalent organic framework nanozyme for Alzheimer's disease treatment

Inhibition of cGAS-STING overactivation has recently emerged as a promising strategy to counteract Alzheimer's disease (AD). However, current cGAS-STING inhibitors as immunosuppressants suffer from instability, non-specific targeting, and innate immune disruption. Here, an endogenous AD brain copper ion-responsive covalent organic framework (COF)-based nanozyme (denoted as TP@PB-COF@NADH) has been designed for targeted inhibition of the cGAS-STING pathway for AD treatment. The effective trapping of excess brain endogenous copper ions by TP@PB-COF@NADH not only inhibits the Cu2+-induced harmful reactive oxygen species (ROS) production which is one of the mediators of cGAS-STING activation, but also activates the nanozyme activity of TP@PB-COF@NADH. Furthermore, the well-prepared nanozyme catalytically generates NAD+ and consumes hydrogen peroxide (H2O2) through second near-infrared (NIR-II) enhanced nicotinamide adenine dinucleotide (NADH) peroxidase (NPX)-like activity, realizing the efficient inhibition of the cGAS-STING pathway and associated neuroinflammation. Moreover, replenishing NAD+ levels efficiently restores mitochondrial function and ATP supply. In vivo studies demonstrate that TP@PB-COF@NADH with NIR-II irradiation significantly improves cognitive function in 3× Tg-AD mice, with a reduction in amyloid-β (Aβ) plaque, neuroinflammation and neuronal damage. Collectively, this work presents a promising approach for AD treatment by using an AD brain harmful excess endogenous copper ion-responsive and efficient nanozyme.

ZnFe2O4/GQDs Nanoparticles as Peroxidase Mimics for Sensitive and Selective Colorimetric Detection of Glucose in Real Samples

Glucose detection is critical in addressing health and medical issues related to irregular blood levels. Colorimetry, a simple, cost-effective, and visually straightforward method, is often employed. Traditional enzymatic detection methods face drawbacks such as high costs, limited stability, and operational challenges. To overcome these, enzyme mimics or artificial nano-enzymes based on inorganic nanomaterials have garnered attention, but their cost and susceptibility to inactivation limit applications. This study presents a ZnFe2O4/GQDs nanocomposite as an innovative enzyme mimic, addressing key requirements like low cost, high stability, biocompatibility, and wide operational range. Synthesized using a simple and inexpensive method, the composite benefits from the synergistic interaction between ZnFe2O4 nanoparticles and graphene quantum dots (GQDs), resulting in excellent magnetic properties, high surface area, and functional versatility. The material demonstrated remarkable sensitivity with a detection limit of 7.0 μM across a range of 5-500 μM and achieved efficient peroxidase-like activity with Km values of 0.072 and 0.068 mM and Vmax of 4.58 × 10⁻8 and 8.29 × 10⁻8 M/s for TMB and H2O2, respectively. The nanocomposite also exhibited robust recyclability, retaining performance over six reuse cycles.

Site-Defined High-Loading Tellurium Single-Atom Nanozymes Anchored on Checkerboard-Patterned Graphyne for Sensor Array Construction

Single-atom nanozymes exhibit unique enzymatic activity due to their active centers, which resemble those of natural metalloenzymes. The design of the anchoring sites of single-atom active centers is an important factor that affects the loading capacity and catalytic activity. Herein, para-nitrogen-doped graphyne with diamond cavity is used as support, and single-atom tellurium atoms are then anchored in the nitrogen-containing graphyne cavities, akin to chess pieces placed on a chessboard grid. Due to the pre-designed regular anchoring sites, the site-defined tellurium single-atom nanozyme (Te SAN) achieves a high Te loading of 19.21 wt.%. Therefore, Te SAN shows good peroxidase-like activity. To explain the enhanced peroxidase-like activity, density functional theory calculations are performed and the results demonstrate that Te doping enhances catalytic activity by lower Gibbs free energy barrier for formation of •OH, a key intermediate in peroxidase-like activity. Finally, based on the inhibitory effect of bisphenols on nanozyme activity, the Te SAN-based sensor array successfully identifies five bisphenols, holding potential for on-site food safety monitoring. The design of the anchoring sites of single atoms in this work provides new ideas for precisely controlling the synthesis of nanozymes, exploring their action mechanisms, and enhancing their activities.

Artificial intelligence driven platform for rapid catalytic performance assessment of nanozymes

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

Hierarchical Assembly of Hemin-Peptide Catalytic Systems on Graphite Surfaces

The formation of molecular hybrid systems with cofactors and peptides on graphite electrodes has recently been demonstrated. The design of peptide sequences is crucial for forming robust catalytic molecular systems on electrodes. However, the relationship between peptide sequences, molecular structure, and catalytic performance has not been fully explored. In this study, we employed peptides with simple dipeptide repeats, which effectively immobilize hemin, to construct a stable catalytic system and investigated the molecular basis of their self-assembly and catalytic activity by varying the sequence. Among peptides containing the dipeptide sequences (YH, VH, and LH), YH demonstrated the most efficient immobilization of hemin, which is catalytically active in electrochemical reactions. Using advanced molecular visualization techniques, specifically frequency modulation atomic force microscopy (FM-AFM), we characterized the well-ordered structures of these peptides on graphite electrodes, revealing their molecular-scale organization. Our findings in electrochemical characterizations include a quantitative evaluation of the surface density of hemin immobilized by self-assembled peptides and the catalytic activity of the peptide-hemin hybrid system under electrochemical conditions in the presence of H2O2. The strong peptide-peptide and peptide-hemin interactions, facilitated by π-π interactions of tyrosine residues, contribute to the system's stability and efficiency. The dipeptide repeats serve as a useful platform to investigate the role of important amino acids, beyond histidine, in stably immobilizing cofactors. These results highlight the potential for developing durable and efficient catalytic interfaces in electrochemical applications.

Fabrication of a hierarchical PtIr@Rh hollow trimetallic nanozyme with a higher specific activity than that of HRP for sensitive colorimetric detection

Nanozymes have emerged as promising alternatives to natural enzymes in various fields, owing to their advantages in terms of stability, cost-effectiveness, and multifunctionality. However, their relatively low catalytic activity compared to natural enzymes remains a major challenge for practical applications. Here, we developed hierarchical PtIr@Rh hollow trimetallic nanorods, where Rh served as the substrate and the surface was decorated with numerous Pt nanoparticles doped with a small amount of Ir. The resulting nanorods exhibited remarkable peroxidase-like activity, with a specific activity of 2287 U mg-1, surpassing that of horseradish peroxidase (HRP). Additionally, the maximum reaction velocity (Vmax) was 1.024 × 10-6 M s-1, and the Michaelis-Menten constant (Km) was 1.706 mM. The enhanced catalytic performance was attributed to the unique hierarchical structure and the small amount of Ir doping, as supported by density functional theory (DFT) calculations. The PtIr@Rh nanozyme was successfully applied for the colorimetric detection of L-ascorbic acid, achieving a rapid detection with a limit of detection (LOD) of 0.12 μM. This study introduces a novel nanozyme with superior specific activity compared to natural enzymes, highlighting its potential for colorimetric sensing applications.

Nanozymes: Innovative Therapeutics in the Battle Against Neurodegenerative Diseases

Neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS) and Huntington's disease (HD), represent a significant challenge to global health due to their progressive nature and the absence of curative treatments. These disorders are characterized by oxidative stress, protein misfolding, and neuroinflammation, which collectively contribute to neuronal damage and death. Recent advancements in nanotechnology have introduced nanozymes-engineered nanomaterials that mimic enzyme-like activities-as promising therapeutic agents. This review explores the multifaceted roles of nanozymes in combating oxidative stress and inflammation in neurodegenerative conditions. By harnessing their potent antioxidant properties, nanozymes can effectively scavenge reactive oxygen species (ROS) and restore redox balance, thereby protecting neuronal function. Their ability to modify surface properties enhances targeted delivery and biocompatibility, making them suitable for various biomedical applications. In this review, we highlight recent findings on the design, functionality, and therapeutic potential of nanozymes, emphasizing their dual role in addressing oxidative stress and pathological features such as protein aggregation. This synthesis of current research underscores the innovative potential of nanozymes as a proactive therapeutic strategy to halt disease progression and improve patient outcomes in neurodegenerative disorders.

A Mo-doped carbon dot nanozyme for enhanced phototherapy in vitro

Cancer is a leading cause of death globally, and traditional treatment methods often come with non-negligible toxic side effects in its treatment, threatening patients' quality of life. Thus, developing novel, efficient, low-toxicity cancer treatment strategies is crucial. Nanozymes, as a class of powerful nanomaterials, can subtly mimic the catalytic activity of natural enzymes, making them a formidable alternative. Hypoxic molybdenum oxide (MoO3-x ), as a typical nanozyme material, possesses unique physical and chemical properties, showing great potential in fields such as cancer treatment. In this study, a simple and rapid one-pot hydrothermal synthesis method was ingeniously employed, innovatively combining molybdenum, which has high biosafety, with safflower, which exhibits anticancer pharmacological activity, to successfully prepare hypoxic molybdenum oxide (MoO3-x )-doped safflower carbon dots (H-Mo-CDs). H-Mo-CDs exhibit exceptional catalase (CAT)-like, peroxidase (POD)-like, and superoxide dismutase (SOD)-like catalytic activities and superior photothermal conversion efficiency and photostability. In vitro cellular experiments have verified their multiple therapeutic potentials in photothermal therapy (PTT), chemodynamic therapy (CDT), and photodynamic therapy (PDT), providing novel ideas and means for precise cancer treatment. This study not only paves an efficient and feasible path for the development of Mo-based nanomaterials as "smart" nanozymes but also injects new vitality and possibilities into the types and applications of nanozymes in cancer treatment.

Comparison of the effects between catalase and superoxide dismutase on regulating macrophage inflammatory response and protecting osteogenic function of periodontal ligament cells

BACKGROUND

Reactive oxygen species (ROS) have been confirmed closely associated with the pathological process of periodontitis, but the specific roles played by different ROS types are still to be investigated. Catalase (CAT) and Superoxide dismutase (SOD) specifically eliminate hydrogen peroxide (H2O2) and superoxide anion (O2•-), respectively. We for the first time compare the effects and mechanisms of CAT and SOD in protecting periodontal ligament cells (PDLCs) against oxidative damage, reducing the expression of macrophage inflammatory factors, and preserving the osteogenic differentiation function of PDLCs by modulating the inflammatory environment.

METHODS

CAT or SOD in combination with lipopolysaccharide (LPS) were added to the culture medium of RAW 264.7 and PDLCs. The intracellular ROS level, lipid peroxidation and DNA damage were observed by confocal microscope. Inflammation levels were assessed by real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot. A co-culture system of macrophages and PDLCs was established, and the osteogenic differentiation of PDLCs was evaluated by alkaline phosphatase staining, alizarin red S staining, RT-qPCR and Western blot. Finally, differentially expressed genes (DEGs) in CAT and SOD were detected by RNA sequencing and the biological functions and signaling pathways involved were analyzed.

RESULTS

CAT or SOD can effectively inhibit intracellular ROS levels, lipid peroxidation and DNA damage, as well as increase the levels of antioxidative molecules and decrease the levels of inflammatory factors. SOD increased the levels of antioxidative molecules more strongly, while CAT reduced inflammatory factors more effectively. The RNA sequencing results indicate that CAT exhibits stronger inhibitory effects on inflammation-related signaling pathways, which could account for the observed differences.

CONCLUSIONS

In this study, we observed differential antioxidant and anti-inflammatory effects between CAT and SOD, which may be associated with CAT's better inhibition of the activation of inflammatory pathways. Our study will provide scientific references for the future development of highly selective ROS- scavenging antioxidant drugs.

Nanozymes meet hydrogels: Fabrication, progressive applications, and perspectives

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

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

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

Graphyne-supported manganese single-atom nanozyme sensor array for bisphenol identification

Bisphenols, as common industrial raw materials, are widely used in food packaging such as plastics. However, their migration and residue may affect the hormone secretion of the human body and then lead to health problems. Therefore, a low-cost, rapid and simple detection method that can simultaneously detect multiple bisphenols is very necessary. In this work, two types of manganese single-atom nanozymes with excellent peroxidase-like activity were synthesized with graphyne as a support. A high-throughput colorimetric sensor array was constructed using three types of nanozymes (Mn-GY, Mn-GY-2N, GY-2N) to distinguish various bisphenols. Due to the absorption of bisphenol molecules on the surface of nanozymes, the activity of nanozymes decreases differently, when different bisphenols are added to the catalytic system. The results proved that the prepared sensor had good linear relationships at both low and high concentrations for determination of five bisphenols. The LODs of BPA, BPS, BPF, BPAF, and Diphenolic Acid were 0.443, 0.280, 0.277, 0.424, and 0.326 μM respectively. Compared with traditional sensors, the sensor array can simultaneously detect multiple analytes with high throughput, showing great advantage in dealing with complex samples. Combined with machine learning algorithms, five bisphenols can be successfully identified by the obtained array data. The sensor array also demonstrated excellent performance in the detection of both mixed samples and real samples. This high-throughput colorimetric sensor array achieves accurate and sensitive detection of bisphenol substances, providing new means and ideas for enhancing food safety. At the same time, the simple and rapid identification of structurally similar compounds demonstrates its potential for more precise analysis, providing possibilities for future development.

Novel ZIF-67-derived Co3O4 hollow nanocages as efficient nanozymes with intrinsic dual enzyme-mimicking activities for colorimetric sensing

Nanozymes with multifaceted functionalities have accrued substantial interest as they provide an expanded spectrum of applications in comparison to their single-active nanozymes. In this endeavor, novel Co3O4 hollow nanocages (COHNs) derived from ZIF-67 were crafted adorned with the exceptional quality of dual-enzymatic prowess by employing a simple co-precipitation and pyrolysis technique, all the while meticulously exploring the intricacies of the catalyst mechanism. Kinetic analyses ascertained that the catalytic behavior of COHNs adhered to the archetypal dynamics of Michaelis-Menten, displaying a higher affinity for 3,3',5,5'-tetramethylbenzidine (TMB) compared to natural enzymes. Leveraging the exceptional peroxidase- and oxidase-mimicking activity of the COHNs, a visual colorimetric assay platform was established for the detection of H2O2, ascorbic acid (AA), and acid phosphatase (ACP), all of which showed high selectivity and good sensitivity. Significantly, by harnessing the enzyme mimic property of COHNs, quantitative detection of H2O2, AA, and ACP unveiled astoundingly low detection limits of 0.0046 µM, 0.15 µM, and 0.0068 mU∙mL-1, respectively. Moreover, the successful detection application in real samples attested to the superior stability and anti-interference ability of the colorimetric sensing system. This study not only provides a novel nanozyme boasting remarkably dual-enzymatic prowess, but also pioneers a rapid and sensitive method for environmental analysis and clinical diagnosis.

Dual-Nanozyme Cascade for System-Wide Specific Colorimetric Detection of Aminoglycoside Antibiotics

Antibiotic contamination has been a significant concern in environmental monitoring. Nanozyme-based colorimetric sensors can provide valuable support for in-field detection. However, the development of sensing elements capable of identifying an entire class of specific antibiotics using a single material poses a considerable challenge. In this work, we present a compartmentalized dual-nanozyme cascade composite (Au@mPDA/PAA-Cu2MI, AmPC) designed for the colorimetric detection of aminoglycoside antibiotics (AGs), and we analyze the catalytic mechanisms of the dual-enzyme system in detail. The AmPC composite possesses both analogue glucose oxidase-like (aGOx-like) and peroxidase-like (POD-like) activities. In this process, AGs with a sugar structure can serve as the initial substrate of the reaction, while the resulting H2O2 acts as the second substrate for colorimetric detection. Using gentamicin (GMC) as a proof of concept, we established a detection range of 0.1-10 μg/mL, with a detection limit (LOD) of 91 ng/mL. In addition, we validated the colorimetric response for other AGs and employed principal component analysis (PCA) for differentiating among various AGs. This approach enables nanozymes to selectively recognize their targets through a cascade mechanism. Furthermore, it facilitates the simultaneous detection and identification of antibiotics, highlighting its potential for in-field applications.

Copper nanocubes as low-cost enzyme mimics in a sarcosine-sensing reaction cascade

The development of simple, inexpensive, deployable clinical diagnostics could have a global impact on public health by making measurements of patient health status more widely accessible to patients regardless of socioeconomic status. Here, we report a novel biosensor for sarcosine using a colorimetric readout created by a hybrid catalyst system using copper nanocubes and the enzyme sarcosine oxidase. The enzyme catalyzes the reaction of sarcosine to generate H2O2, which the copper nanocubes then use as a substrate to create free radicals that convert colorless 3,3',5,5'-tetramethylbenzidine (TMB) to its blue, oxidized form. The sensor showed good substrate affinity for Cu nanocubes and yielded a wide linear response range (0-140 μM) for sarcosine detection, with high selectivity against various interfering species. The limit of detection and limit of quantification were found to be 1.43 μM and 4.7 μM, respectively. We showed that the biosensor maintains function in a complex serum sample matrix, suggesting potential utility in clinical applications. Finally, we demonstrated a prototype based on light emitting diodes (LEDs) and a light-dependent resistor (LDR) for unambiguous visual interpretation using an inexpensive microcontroller potentially suitable for use outside of traditional clinical or analytical laboratories.

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.