Search Results (16)

The prosperity of enzyme-mimicking catalysis has promoted the development of nanozymes with diversified activities, mainly including catalase-like, oxidase-like, peroxidase-like, and superoxide dismutase-like characteristics. Thus far, the reported nanozymes can be roughly divided into five categories, comprising noble metals, metal oxides, carbon-based nanostructures, metal–organic frameworks, and covalent organic frameworks. This review systematically summarizes the research progress of nanozymes for improving catalytic activity toward sensing applications in food safety monitoring. Specifically, we highlight the unique advantages of nanozymes in enhancing the performance of colorimetric, fluorescence, and electrochemical sensors, which are crucial for detecting various food contaminants. Moreover, this review addresses the challenges faced in food safety detection, such as the need for high sensitivity, selectivity, and stability under complex food matrices. Nanozymes offer promising solutions by providing robust catalytic activity, adjustable enzyme-like properties, and excellent stability, even in harsh environments. However, practical implementation challenges remain, including the need for a deeper understanding of nanozyme catalytic mechanisms, improving substrate selectivity, and ensuring long-term stability and large-scale production. By focusing on these aspects, this review aims to provide a comprehensive overview of the current state of nanozyme-based sensors for food safety detection and to inspire future research directions. Full article

With the growing interest in nucleic acids and nanozymes, nucleic acid nanozymes (NANs) have emerged as a promising alternative to traditional enzyme catalysts, combining the advantages of nucleic acids and nanomaterials, and are widely applied in the field of biosensing. This review provides a comprehensive overview of recent studies on NAN-based biosensors. It classifies NANs based on six distinct enzymatic activities: peroxidase-like, oxidase-like, catalase-like, superoxide dismutase-like, laccase-like, and glucose oxidase-like. This review emphasizes how the catalytic activity of nanozymes is significantly influenced by the properties of nucleic acids and explores the regulatory mechanisms governing the catalytic activity of NANs. Additionally, it systematically reviews important research progress on NANs in colorimetric, fluorescent, electrochemical, SERS, and chemiluminescent sensors, offering insights into the development of the NAN field and biosensor applications. Full article

Objectives: To design a multifunctional nanozyme hydrogel with antibacterial, photo-responsive nitric oxide-releasing, and antioxidative properties for promoting the healing of infected wounds. Methods: We first developed ultra-small silver nanoparticles (NPs)-decorated sodium nitroprusside-doped Prussian blue (SNPB) NPs, referred to as SNPB@Ag NPs, which served as a multifunctional nanozyme. Subsequently, this nanozyme, together with geniposide (GE), was incorporated into a thermo-sensitive hydrogel, formulated from Poloxamer 407 and carboxymethyl chitosan, creating a novel antibacterial wound dressing designated as GE/SNPB@Ag hydrogel. The physical properties of a GE/SNPB@Ag hydrogel were systematically investigated. Results: After embedding the nanozyme and GE, the resulting GE/SNPB@Ag hydrogel retains its thermosensitive properties and exhibits sustained release characteristics. In addition to its catalase-like activity, the nanozyme demonstrates high photothermal conversion efficiency, photo-induced nitric oxide release, and antibacterial activity. In addition, the hydrogel exhibits favorable antioxidant properties and high biocompatibility. The results of animal experiments demonstrate that the composite hydrogel combined with laser irradiation is an effective method for promoting infected wound healing. Conclusions: In vitro and in vivo studies indicate that the resulting GE/SNPB@Ag hydrogel holds significant potential for the treatment of infected wounds and for further clinical applications. Full article

Creatine catalase (CAT), superoxide dismutase (SOD), and NADPH oxidase (NOX) are natural enzyme molecules that play a crucial role in regulating reactive oxygen species (ROS) in biological systems. They maintain life activities and eliminate pathogens by catalyzing various biochemical reactions. However, natural enzymes have some drawbacks in ROS control; they may lose activity under certain environmental conditions, such as high temperatures, extreme pH values, or the presence of organic solvents, which affects their stability and reliability in different applications. The construction of artificial nanozymes is an emerging technology that could probably solve the problems existing in natural enzymes. This study introduces a type of dendritic platinum–iron oxide (DPIO) nanozyme. The unique dendritic structure of this DPIO nanozyme provides a high surface area-to-volume ratio, and the addition of a platinum layer on the surface offers stability, thereby effectively enhancing the catalytic efficiency of producing reactive oxygen species (ROS). The combination of iron-based Fenton reactions and platinum-based Fenton-like reactions in this DPIO nanozyme drastically improves ROS catalytic efficiency. This artificial nanozyme has a high level of biosafety and displays no cytotoxicity. The development of DPIO nanozymes marks a significant advancement in the technology of artificial nanozymes. Full article

Staphylococcus aureus is one of the leading causes of skin and soft tissue infections, and it is even life-threatening if it enters the bloodstream, lung or heart. In the present work, we proposed a novel colorimetric biosensor for the detection of S. aureus through hydrogen peroxide consumption. An onion-like carbon nanozyme with high peroxidase-like activity was prepared, which competed with the endogenous catalase of S. aureus in consuming hydrogen peroxide. This reaction was further characterized by the colorimetric reaction of 3,3′,5,5′-tetramethylbenzidine. The results showed that our approach allowed for the simple and rapid determination of S. aureus, with a linear range of 2 × 10⁴ to 2 × 10⁷ CFU/mL. Moreover, our method displayed good selectivity, with Bacillus subtilis and Escherichia coli showing negligible responses at the concentration of 2 × 10⁵ CFU/mL. The application of the as-prepared biosensor to analyze S. aureus in real water samples yielded recovery rates ranging from 95% to 112%, with relative standard deviations less than 7%. The method demonstrated good accuracy and specificity, which offers a novel approach for the simple and selective detection of S. aureus. Full article

Transition metal oxide (TMO)-based nanozymes have appeared as hopeful tools for antitumor applications due to their unique catalytic properties and ability to modulate the tumor microenvironment (TME). The purpose of this review is to provide an overview of the latest progress made in the field of TMO-based nanozymes, focusing on their enzymatic activities and participating metal ions. These nanozymes exhibit catalase (CAT)-, peroxidase (POD)-, superoxide dismutase (SOD)-, oxidase (OXD)-, and glutathione oxidase (GSH-OXD)-like activities, enabling them to regulate reactive oxygen species (ROS) levels and glutathione (GSH) concentrations within the TME. Widely studied transition metals in TMO-based nanozymes include Fe, Mn, Cu, Ce, and the hybrid multimetallic oxides, which are also summarized. The review highlights several innovative nanozyme designs and their multifunctional capabilities. Despite the significant progress in TMO-based nanozymes, challenges such as long-term biosafety, targeting precision, catalytic mechanisms, and theoretical supports remain to be addressed, and these are also discussed. This review contributes to the summary and understanding of the rapid development of TMO-based nanozymes, which holds great promise for advancing nanomedicine and improving cancer treatment. Full article

Transition metal doping is an ideal strategy to construct multifunctional and efficient nanozymes for biosensing. In this work, a metal-doped CoMnO_x nanozyme was designed and synthesized by hydrothermal reaction and high-temperature calcination. Based on its oxidase activity, an “on-off-on” smartphone sensing platform was established to detect ziram and Cu²⁺. The obtained flower-shaped CoMnO_x could exhibit oxidase-, catalase-, and laccase-like activities. The oxidase activity mechanism of CoMnO_x was deeply explored. O₂ molecules adsorbed on the surface of CoMnO_x were activated to produce a large amount of O₂^·-, and then, O₂^·- could extract acidic hydrogen from TMB to produce blue oxTMB. Meanwhile, TMB was oxidized directly to the blue product oxTMB via the high redox ability of Co species. According to the excellent oxidase-like activity of CoMnO_x, a versatile colorimetric detection platform for ziram and Cu²⁺ was successfully constructed. The linear detection ranges for ziram and Cu²⁺ were 5~280 μM and 80~360 μM, and the detection limits were 1.475 μM and 3.906 μM, respectively. In addition, a portable smartphone platform for ziram and Cu²⁺ sensing was established for instant analysis, showing great application promise in the detection of real samples including environmental soil and water. Full article

Ulcerative colitis (UC) is a refractory chronic inflammatory disease involving the colon and rectum, falling under the category of inflammatory bowel disease (IBD). The accumulation of reactive oxygen species (ROS) in local tissues has been identified as a crucial contributor to the escalation of inflammatory responses. Therefore, eliminating ROS in the inflamed colon is a promising approach to treating UC. Nanomaterials with intrinsic enzyme-like activities (nanozymes) have shown significant therapeutic potential in UC. In this study, we found that platinum nanoparticles (Pt NPs) exhibited remarkable superoxide dismutase (SOD) and catalase (CAT) cascade catalytic activities, as well as effective hydroxyl radical (•OH) scavenging ability. The in vitro experiments showed that Pt NPs could eliminate excessive ROS to protect cells against oxidative stress. In the colitis model, oral administration of Pt NPs (loaded in chitosan/alginate hydrogel) could significantly alleviate UC, including reducing the colon length, the damaged epithelium, and the infiltration of inflammatory cells. Without appreciable systemic toxicity, Pt NPs represent a novel therapeutic approach to UC and are expected to achieve long-term inflammatory remission. Full article

Gold nanoparticles (AuNPs) can be described as nanozymes, species that are able to mimic the catalytic activities of several enzymes, such as oxidase/peroxidase, reductase, or catalase. Most studies in the literature focus on the colloidal suspension of AuNPs, and it is obvious that their immobilization could open the doors to new applications thanks to their increased stability in this state. This work aimed to investigate the behavior of surfaces covered by immobilized AuNPs (iAuNPs). Citrate-stabilized AuNPs (AuNPs-cit) were synthesized and immobilized on glass slides using a simple dip coating method. The resulting iAuNPs were characterized (surface plasmon resonance, microscopy, quantification of immobilized AuNPs), and their multi-enzymatic-like activities (oxidase-, peroxidase-, and catalase-like activity) were evaluated. The comparison of their activities versus AuNPs-cit highlighted their added value, especially the preservation of their activity in some reaction media, and their ease of reuse. The huge potential of iAuNPs for heterogeneous catalysis was then applied to the degradation of two model molecules of hospital pollutants: metronidazole and methylene blue. Full article

Antioxidant enzymes such as catalase, superoxide dismutase, and glutathione peroxidase play important roles in the inhibition of oxidative-damage-related pathological diseases. However, natural antioxidant enzymes face some limitations, including low stability, high cost, and less flexibility. Recently, antioxidant nanozymes have emerged as promising materials to replace natural antioxidant enzymes for their stability, cost savings, and flexible design. The present review firstly discusses the mechanisms of antioxidant nanozymes, focusing on catalase-, superoxide dismutase-, and glutathione peroxidase-like activities. Then, we summarize the main strategies for the manipulation of antioxidant nanozymes based on their size, morphology, composition, surface modification, and modification with a metal-organic framework. Furthermore, the applications of antioxidant nanozymes in medicine and healthcare are also discussed as potential biological applications. In brief, this review provides useful information for the further development of antioxidant nanozymes, offering opportunities to improve current limitations and expand the application of antioxidant nanozymes. Full article

New nanotechnologies for imaging molecules are widely being applied to visualize the expression of specific molecules (e.g., ions, biomarkers) for disease diagnosis. Among various nanoplatforms, nanozymes, which exhibit enzyme-like catalytic activities in vivo, have gained tremendously increasing attention in molecular imaging due to their unique properties such as diverse enzyme-mimicking activities, excellent biocompatibility, ease of surface tenability, and low cost. In addition, by integrating different nanoparticles with superparamagnetic, photoacoustic, fluorescence, and photothermal properties, the nanoenzymes are able to increase the imaging sensitivity and accuracy for better understanding the complexity and the biological process of disease. Moreover, these functions encourage the utilization of nanozymes as therapeutic agents to assist in treatment. In this review, we focus on the applications of nanozymes in molecular imaging and discuss the use of peroxidase (POD), oxidase (OXD), catalase (CAT), and superoxide dismutase (SOD) with different imaging modalities. Further, the applications of nanozymes for cancer treatment, bacterial infection, and inflammation image-guided therapy are discussed. Overall, this review aims to provide a complete reference for research in the interdisciplinary fields of nanotechnology and molecular imaging to promote the advancement and clinical translation of novel biomimetic nanozymes. Full article

Surface engineering of nanozymes has been recognized as a potent strategy to improve their catalytic activity and specificity. We synthesized polydopamine-coated Co₃O₄ nanoparticles (PDA@Co₃O₄ NPs) through simple dopamine-induced self-assembly and demonstrated that these NPs exhibit catalase-like activity by decomposing H₂O₂ into oxygen and water. The activity of PDA@Co₃O₄ NPs was approximately fourfold higher than that of Co₃O₄ NPs without PDA, possibly due to the additional radical scavenging activity of the PDA shell. In addition, PDA@Co₃O₄ NPs were more stable than natural catalase under a wide range of pH, temperature, and storage time conditions. Upon the addition of a sample containing sulfide ion, the activity of PDA@Co₃O₄ NPs was significantly inhibited, possibly because of increased mass transfer limitations via the absorption of the sulfide ion on the PDA@Co₃O₄ NP surface, along with NP aggregation which reduced their surface area. The reduced catalase-like activity was used to determine the levels of sulfide ion by measuring the increased fluorescence of the oxidized terephthalic acid, generated from the added H₂O₂. Using this strategy, the target sulfide ion was sensitively determined to a lower limit of 4.3 µM and dynamic linear range of up to 200 µM. The fluorescence-based sulfide ion assay based on PDA@Co₃O₄ NPs was highly precise when applied to real tap water samples, validating its potential for conveniently monitoring toxic elements in the environment. Full article

In this work, an efficient synthesis of bionanohybrids as artificial metalloenzymes (Cu, Pd, Ag, Mn) based on the application of an enzyme as a scaffold was described. Here we evaluated the effect of changing the metal, pH of the medium, and the amount of enzyme in the synthesis of these artificial metalloenzymes, where changes in the metal species and the size of the nanoparticles occur. These nanozymes were applied in the degradation of hydrogen peroxide for their evaluation as mimetics of catalase activity, the best being the Mn@CALB-H₂O, which presented MnO₂ nanostructures, with three-fold improved activity compared to Cu₂O species, CuNPs@CALB-P, and free catalase. Full article

(1) Background: Acute ischemic stroke (IS) is one of the main causes of human disability and death. Therefore, multifunctional nanosystems that effectively cross the blood–brain barrier (BBB) and efficiently eliminate reactive oxygen species (ROS) are urgently needed for comprehensive neuroprotective effects. (2) Methods: We designed a targeted transferrin (Tf)-based manganese dioxide nanozyme (MnO₂@Tf, MT) using a mild biomimetic mineralization method for rebalancing ROS levels. Furthermore, MT can be efficiently loaded with edaravone (Eda), a clinical neuroprotective agent, to obtain the Eda-MnO₂@Tf (EMT) nanozyme. (3) Results: The EMT nanozyme not only accumulates in a lesion area and crosses the BBB but also possesses satisfactory biocompatibility and biosafety based on the functional inheritance of Tf. Meanwhile, EMT has intrinsic hydroxyl radical-scavenging ability and superoxide-dismutase-like and catalase-like nanozyme abilities, allowing it to ameliorate ROS-mediated damage and decrease inflammatory factor levels in vivo. Moreover, the released Mn²⁺ ions in the weak acid environment of the lesion area can be used for magnetic resonance imaging (MRI) to monitor the treatment process. (4) Conclusions: Our study not only paves a way to engineer alternative targeted ROS scavengers for intensive reperfusion-induced injury in ischemic stroke but also provides new insights into the construction of bioinspired Mn-based nanozymes. Full article

Nanozymes, nanomaterials with enzyme-like activities, are becoming powerful competitors and potential substitutes for natural enzymes because of their excellent performance. Nanozymes offer better structural stability over their respective natural enzymes. In consequence, nanozymes exhibit promising applications in different fields such as the biomedical sector (in vivo diagnostics/and therapeutics) and the environmental sector (detection and remediation of inorganic and organic pollutants). Prussian blue nanoparticles and their analogues are metal–organic frameworks (MOF) composed of alternating ferric and ferrous irons coordinated with cyanides. Such nanoparticles benefit from excellent biocompatibility and biosafety. Besides other important properties, such as a highly porous structure, Prussian blue nanoparticles show catalytic activities due to the iron atom that acts as metal sites for the catalysis. The different states of oxidation are responsible for the multicatalytic activities of such nanoparticles, namely peroxidase-like, catalase-like, and superoxide dismutase-like activities. Depending on the catalytic performance, these nanoparticles can generate or scavenge reactive oxygen species (ROS). Full article