Peroxidase Nanozyme Research Articles

Fe-Coordinated Carbon Nanozyme Dots as Peroxidase-Like Nanozymes and Magnetic Resonance Imaging Contrast Agents.

The catalytic activities of currently developed peroxidase-mimic nanozymes are generally limited. Therefore, further efforts are still needed to improve the catalytic performance of peroxidase nanozymes. Herein, we synthesized Fe-coordinated carbon nanozyme dots (Fe-CDs) that can serve as both efficient peroxidase nanozymes and T2-magnetic resonance imaging (MRI) contrast agents. The intrinsic peroxidase-like activity of the Fe-CDs was explored by catalytic oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) with hydrogen peroxide (H2O2). The product showed better performance over natural horseradish peroxidase (HRP) and other mimetic peroxidases. Quantification of glucose and ascorbic acid detection showed that this nanozyme could be used to detect a minimum limit as low as 5 μM glucose. Moreover, the colorimetric detection technique was used to detect serum glucose in mice, and the detection result was comparable with autobiochemistry analyzer results using a glucose assay kit. Furthermore, the Fe-CDs showed good magnetism properties and provided promising MR imaging of tumors with excellent biocompatibility.

Ultrathin two-dimensional carbon nanosheets with highly active Cu-Nx sites as specific peroxidase mimic for determining total antioxidant capacity

Cu,N-codoped carbon nanosheets (Cu-NC) with highly active Cu-N x sites were fabricated via a low-cost and facile nitrogen-doping strategy, and successfully demonstrated as a novel specific peroxidase mimic enzyme for determining total antioxidant capacity. • A facile strategy was proposed to fabricate Cu-NC specific peroxidase nanozyme. • Relative to Cu-C and N-C, Cu-NC shows 19.06 and 15.84-fold peroxidase activity rise. • A highly sensitive colorimetric biosensor was developed for glucose and H 2 O 2 . • The method was successfully applied to TAC quantification in drinks. We designed the Cu,N-codoped carbon (Cu-NC) nanosheets with highly active Cu-N x sites through a facile nitrogen-doping strategy that employed copper MOF as a precursor and dicyandiamide as a N source, respectively. The Cu-NC displayed an ultrathin two dimensional sheet structure. The ultrathin nanosheet structure and Cu,N-codoping endowed Cu-NC highly exposed active sites. The Cu-NC showed superior and specific peroxidase-like activity able to greatly promote TMB oxidation by H 2 O 2 . Relative to that of Cu doped carbon (Cu-C) and N doped carbon (N-C), the peroxidase mimic activity of the optimized Cu-NC-700 increased by 19.06-fold and 15.84-fold, respectively. The mechanism investigation revealed that the ·OH is the main active oxygen specie for the peroxidase-like activity of Cu-NC-700. The Cu-NC-700 showed high affinity to TMB and H 2 O 2 with K m values of 0.077 mM and 0.928 mM, which were 4.63 and 2.98 times lower than those of HRP, respectively. The high and specific peroxidase mimic activity enables the Cu-NC-700 for sensitively detecting H 2 O 2 , glucose, and ascorbic acid with limit detection of 10, 100 and 90 nM, respectively. The assay was successfully used to evaluate the total antioxidant capacity of real drinks.

High-Performance Self-Cascade Pyrite Nanozymes for Apoptosis–Ferroptosis Synergistic Tumor Therapy

As next-generation artificial enzymes, nanozymes have shown great promise for tumor catalytic therapy. In particular, their peroxidase-like activity has been employed to catalyze hydrogen peroxide (H2O2) to produce highly toxic hydroxyl radicals (•OH) to kill tumor cells. However, limited by the low affinity between nanozymes with H2O2 and the low level of H2O2 in the tumor microenvironment, peroxidase nanozymes usually produced insufficient •OH to kill tumor cells for therapeutic purposes. Herein, we present a pyrite peroxidase nanozyme with ultrahigh H2O2 affinity, resulting in a 4144- and 3086-fold increase of catalytic activity compared with that of classical Fe3O4 nanozyme and natural horseradish peroxidase, respectively. We found that the pyrite nanozyme also possesses intrinsic glutathione oxidase-like activity, which catalyzes the oxidation of reduced glutathione accompanied by H2O2 generation. Thus, the dual-activity pyrite nanozyme constitutes a self-cascade platform to generate abundant •OH and deplete reduced glutathione, which induces apoptosis as well as ferroptosis of tumor cells. Consequently, it killed apoptosis-resistant tumor cells harboring KRAS mutation by inducing ferroptosis. The pyrite nanozyme also exhibited favorable tumor-specific cytotoxicity and biodegradability to ensure its biosafety. These results indicate that the high-performance pyrite nanozyme is an effective therapeutic reagent and may aid the development of nanozyme-based tumor catalytic therapy.

Breaking the pH limitation of peroxidase-like CoFe2O4 nanozyme via vitriolization for one-step glucose detection at physiological pH

In recent years, a growing number of nanosized materials that can mimic the catalytic characteristics of some natural enzymes have experienced a period of rapid development. Among these nanomaterials defined as ‘nanozymes’, peroxidase-mimicking materials draw intensive interest because of their potential applications in various fields, including biosensing, medicine, and environmental engineering. Nonetheless, most of currently explored peroxidase nanozymes exhibit favorable activity only in acidic environments, which greatly restricts their use especially in biochemical analysis. Developing peroxidase mimics with good catalytic performance in a broad pH range is highly desired and still challenging. Herein, we report a vitriolization strategy to broaden the catalytic pH scope of peroxidase-like CoFe2O4. The vitriolization process endows the nanomaterial with sustainable acidity on its surface. As a result, the obtained peroxidase nanozyme (SO42−/CoFe2O4) exhibits good catalytic activity in neutral or even weak alkaline solutions. This provides us a one-step assay for colorimetric glucose detection in one pot at physiological pH via combining the proposed peroxidase mimic with glucose oxidase, which shows advantages of easier operation and faster detection while offering comparable analytical performance.

Tumor-activatable ultrasmall nanozyme generator for enhanced penetration and deep catalytic therapy

Tumor-activatable ultrasmall nanozyme generation is an unprecedented strategy to overcome intrinsically fatal defects of traditional reactive oxygen species (ROS)-based nanoagents for deep tumor penetration, including limited tissue-penetrating depth of external energy, heavy reliance on oxygen and nonspecific toxicity of therapeutic agents. Here, based on the cascade reaction between glucose oxidase (GOx) and ultrasmall peroxidase nanozyme embedded into acid-dissociable zeolitic imidazolate framework-8 (ZIF-8), such a tumor-activatable ultrasmall nanozyme generator is designed for enhanced penetration and deep catalytic therapy. With the aid of mildly acidic tumor microenvironment, the produced gluconic acid from intratumoral glucose can gradually induce the dissociation of ZIF-8 to release ultrasmall peroxidase nanozyme with significant intratumoral penetration. On the other hand, the generated hydrogen peroxide with relatively long-life can be subsequently catalyzed by penetrated peroxidase nanozyme into toxic hydroxyl radicals for deep catalytic therapy. In this way, the well-designed nanoplatform not only can greatly enhance tumor penetration but also directly induce exogenous ROS without oxygen participation and external energy input, thereby thoroughly avoiding the inactivation of traditional ROS-based nanoagents in the extremely hypoxic tumor center and finally resulting in remarkable deep catalytic therapy.

Core-shell Au@Co-Fe hybrid nanoparticles as peroxidase mimetic nanozyme for antibacterial application

Nanozymes have been developed as alternative for enzymes to overcome practical limitations of enzymes in industry and medicine. Infectious diseases are becoming severe threat to public health. Hence, peroxidase nanozyme for combating bacteria have been designed. Core-Shell Au@Co-Fe hybrid nanoparticles (Au@Co-Fe NPs) were synthesized. The structure of Au@Co-Fe NPs was characterized by UV–vis and FT-IR spectroscopic methods. The size, zeta potential and spherical morphology of Au@Co-Fe NPs were determined by DLS, TEM and AFM techniques. Au@Co-Fe NPs has been evaluated as peroxidase mimic nanozyme. The peroxidase mimetic activity of gold nanoparticles, Co (II) and Fe (III) were measured and compared with that obtained for native HRP. The enzymatic measured activity was 50% of native horse radish peroxidase. Additionally, Au@Co-Fe NPs was evaluated as antibacterial agent against four selected standard pathogenic bacteria as Escherichia coli, Pseudomonas aeruginosa (as gram negative) and Staphylococcus aureus, and Bacillus cereus (as gram positive).

Enhancement of gold nanoclusters-based peroxidase nanozymes for detection of tetracycline

Gold nanoclusters (AuNCs) have shown great potential in mimicking the redox properties of nanozymes. However, limited fundamental knowledge and a lack of an effective means have hindered the enhancement of their catalysis efficiency. In this study, we report a simple protocol for the synthesis of D-trytophan methyl ester protected AuNCs and exhibit their peroxidase-like activity in a chromogenic reaction coupling with 3,3′,5,5′-tetramethylbenzidine-H2O2. Interestingly, the addition of tetracycline resulted in a remarkable acceleration of the redox reaction rate with AuNCs as the nanozymes due to the increased levels of reactive oxygen species. The UV–vis adsorption intensity of oxidized 3,3′,5,5′-tetramethylbenzidine presented a good linear relationship with the concentration of tetracycline in the range of 1.5–30.0 µM and the limit of detection of the method was 0.2 µM. The proposed assay was further applied in the analysis of serum tetracycline. This study enriches our basic understanding of the enhancement of the catalytic efficiency of AuNCs-based nanozymes.

A novel nanozyme based on selenopeptide-modified gold nanoparticles with a tunable glutathione peroxidase activity

In this study, we successfully prepared a selenium-containing pentapeptide (Sec-Arg-Gly-Asp-Cys)-modified gold nanozyme that exhibited glutathione peroxidase (GPx) activity. The nanozyme catalyzed the reduction of H2O2 by GSH, and its GPx activity was about 14 times that of free selenopeptide. Kinetic analysis indicated that the nanozyme changed the catalytic mechanism from the ping-pong mechanism of the peptide to an ordered mechanism. This indicated that the gold nanoparticle acts as a scaffold that may limit the mobility and constrain the conformation of the peptides, hence exposing the active center to the substrates, and allowing the multivalent selenopeptide to act cooperatively to increase the catalytic rate. Furthermore, upon addition of cysteamine to regulate the surface chemistry of gold nanoparticles and thereby modify the microenvironment of the active center, this nanozyme system could achieve a tunable GPx activity that was about 20 times that of free selenopeptide. Thus, the rational design of the nanozyme greatly improved and amplified the catalytic activity of the ‘active unit’ peptide. This study provides an alternative strategy to establish GPx mimics and provides new insights for the use of gold nanoparticles to develop nanozymes with biological applications.

Enhanced peroxidase-like activity of AuNPs loaded graphitic carbon nitride nanosheets for colorimetric biosensing

Nanozymes have emerged as promising alternatives to overcome the high cost and low stability issues of natural enzymes. Particularly, those with peroxidase-like activities have been extensively studied to construct versatile biosensors. In this article, we demonstrate that the modification of the graphitic carbon nitride nanosheets (g-C3N4 nanosheets) by plasmonic gold nanoparticles (AuNPs) greatly enhances its catalytic performance as peroxidase mimetic. In the presence of H2O2, the AuNPs@g-C3N4 nanosheets can catalyze the redox reaction of 3,3′,5,5′- tetramethylbenzidine (TMB) to produce a blue color. Based on the observation, a colorimetric sensing method for glucose is further developed with the assistance of glucose oxidase (GOx). The linear range for glucose is from 5 to 100 μmol L−1 (R2 = 0.9967) and the limit of detection (LOD) is 1.2 μmol L−1. The LOD can be further lowered down to 0.75 μmol L−1 by using H2SO4 as termination agent and measuring the absorbance of the yellow product at λ = 451 nm. Moreover, the practical usefulness of AuNPs@g-C3N4 nanosheets as a peroxidase nanozyme for glucose determination in human serum and urine is also demonstrated.

Thermodynamics and kinetic analysis of carbon nanofibers as nanozymes.

PurposeEvaluation of structural features, thermodynamics and kinetic properties of carbon nanofibers (CNFs) as artificial nanoscale enzymes (nanozyme).MethodsSynthesis of CNFs was done using chemical vapor deposition, and transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM) and energy-dispersive x-ray spectroscopy (EDX) were used to provide information on the morphology, elemental monitoring and impurity assay of the CNFs. The thermal features of the CNFs were evaluated using differential thermal analysis (DTA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) derivative and TGA. The calculated thermo-physical parameters were melting temperature (Tm), weight loss maximum temperature (Tmax) and enthalpy of fusion (ΔHfusion). Catalytic activity was assayed by a 4-aminoantypyrine (4-AAP)-H2O2 coupled colorimetric system by UV-visible spectroscopy.ResultsFE-SEM and TEM analysis demonstrated parallel graphitic layers and uniformity of atomic orientation and morphology. The EDX spectra approved carbon element as major signal and presence of partial Ti as impurities of CNFs during CVD process. The DTA thermogram showed the endothermic process had a maximum temperature of 82.27°C at −15.48 mV and that thermal decomposition occurred at about 200°C. The TGA-differential gravimetric analysis thermogram showed that Tmax was 700°C. The DSC heat flow curve showed a melting temperature (Tm) of 254.52°C, ΔHfusion of 3.84 J^.g−1, area under the curve of 58.58 mJ and Te (onset) and Tf (end set) temperatures of 246.60°C and 285.67°C, respectively. The peroxidase activity of the CNFs obeyed the Michaelis–Menten equation with a double-reciprocal curve and the calculated Km, Kcat and Vmax kinetic parameters.ConclusionCNFs as peroxidase nanozymes are intrinsically strong and stable nanocatalysts under difficult thermal conditions. The peroxidase activity was demonstrated, making these CNFs candidates for analytical tools under extreme conditions.

바이오센서 응용을 위한 페록시다아제 모방 나노 소재

Biocatalysts, referred as enzymes, have been widely used in life, industrial, medical, and biological fields due to their high catalytic activity and substrate specificity for specific reaction. However, it has disadvantages in industrial applications due to the drawbacks in its characteristics as a catalyst, such as the high cost, the narrow operation conditions in terms of pH and temperature, and the low durability. Recently, many studies on nanozymes for replacing enzymes have been widely conducted to overcome these drawbacks. The nanozyme has a relatively wide pH and temperature operation range as compared with the enzyme, which is a kind of protein, and has a high durability over a long period of time. It is also expected to be able to be mass-produced at relatively low cost. However, the nanozymes still lacks of the substrate specificity, which is one of the most important features of enzymes. Furthermore, only few nanozymes have been reported which exhibits higher or comparable catalytic activity compared with enzymes. This review first discusses the classification of the nanozymes and the corresponding catalytic reactions, focusing on the most developed peroxidase -mimicking nanozymes. Then, it summarizes the most effective peroxidase nanozymes including iron oxides, nanocarbon, and iron- and carbon composite materials and their corresponding reaction mechanisms. After that, the nanotechnology- based approaches to improve the catalytic activity of nanozymes as well as the substrate specificity are covered. Furthermore, the current major application of nanozyme to the biosensor are introduced. Finally, the future directions for nanozyme researches and the applications are suggested.

Enhanced Peroxidase Mimetic Activity of Porous Iron Oxide Nanoflakes

AbstractPorous nanomaterials with superior peroxidase mimetic activity (nanozyme) at room temperature have gained increasing attention as potential alternatives to natural peroxidase enzymes. Herein, we report the application of porous iron oxide nanoflakes (IONFs), synthesized using the combination of solvothermal method and high‐temperature calcination as peroxidase nanozyme for the oxidation of 3,3′,5,5′‐tetramethylbenzidine (TMB) in the presence of H2O2. The four IONF catalysts possess porous structures with a wide pore size distribution between 2–30 nm and high specific surface areas around to 200 m2 g−1. The increase of calcination temperature of the IONFs from 250 °C to 400 °C resulted in a gradual decrease in their specific surface area and Michaelis‐Menten constant (Km) for TMB oxidation. The optimum IONF sample showed a much lower Km at 0.24 mM (towards TMB) compared to natural enzyme horseradish peroxidase (HRP) at 0.434 mM, revealing the promising potential of the as‐prepared IONFs as alternatives to HRP for biosensing applications.

Alkaline-promoted regulation of the peroxidase-like activity of Ni/Co LDHs and development bioassays

Nanozymes’ activities could be regulated by a simple and effective pH change in an in situ manner. In this work, for the first time, the peroxidase-like activity of Ni/Co layered double hydroxides (LDHs) was regulated via the alkaline-promoted reaction of fluorogenic substrate homovanillic acid and H2O2, and a promising tool for pH sensing was developed over the pH range of 8.3–9.6. As peroxidase nanozyme model, Ni/Co LDHs showed ease of preparation, low-cost, and water-solubility, which played an important role in this luminescence system. Based on the pH-dependent regulation of the Ni/Co LDHs activity, we constructed the bioassay platform for the determination urea, urease, penicillin G, and penicillinase with a wide linear range of 17–1000 µM, 3.3–270 mU mL−1, 3.3–1300 µM and 3.3–100 mU mL−1, respectively. This study not only demonstrated the alkaline-promoted modulation the nanozymes’ activities, but also established a facile approach to develop novel bioassays.

Standardized assays for determining the catalytic activity and kinetics of peroxidase-like nanozymes.

Nanozymes are nanomaterials exhibiting intrinsic enzyme-like characteristics that have increasingly attracted attention, owing to their high catalytic activity, low cost and high stability. This combination of properties has enabled a broad spectrum of applications, ranging from biological detection assays to disease diagnosis and biomedicine development. Since the intrinsic peroxidase activity of Fe3O4 nanoparticles (NPs) was first reported in 2007, >40 types of nanozymes have been reported that possess peroxidase-, oxidase-, haloperoxidase- or superoxide dismutase-like catalytic activities. Given the complex interdependence of the physicochemical properties and catalytic characteristics of nanozymes, it is important to establish a standard by which the catalytic activities and kinetics of various nanozymes can be quantitatively compared and that will benefit the development of nanozyme-based detection and diagnostic technologies. Here, we first present a protocol for measuring and defining the catalytic activity units and kinetics for peroxidase nanozymes, the most widely used type of nanozyme. In addition, we describe the detailed experimental procedures for a typical nanozyme strip-based biological detection test and demonstrate that nanozyme-based detection is repeatable and reliable when guided by the presented nanozyme catalytic standard. The catalytic activity and kinetics assays for a nanozyme can be performed within 4 h.

Nickel metal-organic framework 2D nanosheets with enhanced peroxidase nanozyme activity for colorimetric detection of H2O2

A two-dimensional (2D) Ni based metal-organic framework (MOF) nanosheets were synthesized using a one-step solvent-thermal method. The as-prepared nanosheets were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and energy disperse spectroscopy (EDS) mapping. Ni-MOF nanosheet was first time found to used as a peroxidase mimetic with catalytic activities and could catalyze the oxidation of the substrate 3,3,5,5-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2). Catalytic mechanism analysis suggested the enzymatic kinetics of Ni-MOF nanosheets followed typical Michaelis-Menten theory and Ni-MOF nanosheets possess a higher affinity for two substrates (TMB and H2O2) than horseradish peroxidase (HRP). Furthermore, Ni-MOF nanosheet was applied to establish an H2O2 colorimetric sensor which deserves a wide linear range of 0.04 ~ 160 μM and a low detection limit of 8 nM. Also the application of this sensor for H2O2 detection in human serum and disinfectant was demonstrated and satisfactory results were obtained. Thus, the simple and sensitive Ni-MOF/TMB/H2O2 colorimetric system has great promising applications in clinical medicine and food environment analysis.

Few-layered MoSe2 nanosheets as an efficient peroxidase nanozyme for highly sensitive colorimetric detection of H2O2 and xanthine.

Molybdenum-containing and selenium-containing enzymes are generally prevalent in the biosphere, and the active sites of these involve molybdenum and selenium respectively. Herein, we for the first time demonstrated that few-layered molybdenum selenide (MoSe2) nanosheets possess intrinsic peroxidase-like activity. The few-layered MoSe2 nanosheets were prepared by a simple liquid exfoliation method. The catalytic process of the MoSe2 nanosheets accords with the Michaelis-Menten behavior and they have a higher affinity to both TMB and H2O2 compared to HRP. In addition, we established that the MoSe2 nanosheets catalyze the oxidation of TMB by promoting the electron transfer process from TMB to H2O2. More importantly, we applied the MoSe2 nanosheets to the field of biological detection by developing a highly sensitive and selective colorimetric detection of H2O2 and xanthine concentration. With these advantages, the few-layered MoSe2 nanosheets have critical potential in the diagnostics and biomedical fields.

Carbon Nanodots as Peroxidase Nanozymes for Biosensing.

‘Nanozymes’, a term coined by Scrimin, Pasquato, and co-workers to describe nanomaterials with enzyme-like characteristics, represent an exciting and emerging research area in the field of artificial enzymes. Indubitably, the last decade has witnessed substantial advancements in the design of a variety of functional nanoscale materials, including metal oxides and carbon-based nanomaterials, which mimic the structures and functions of naturally occurring enzymes. Among these, carbon nanodots (C-dots) or carbon quantum dots (CQDs) offer huge potential due to their unique properties as compared to natural enzymes and/or classical artificial enzymes. In this mini review, we discuss the peroxidase-like catalytic activities of C-dots and their applications in biosensing. The scope intends to cover not only the C-dots but also graphene quantum dots (GQDs), doped C-dots/GQDs, carbon nitride dots, and C-dots/GQDs nanocomposites. Nevertheless, this mini review is designed to be illustrative, not comprehensive.

Magnetic Iron Oxide Nanoparticle Seeded Growth of Nucleotide Coordinated Polymers.

The introduction of functional molecules to the surface of magnetic iron oxide nanoparticles (NPs) is of critical importance. Most previously reported methods were focused on surface ligand attachment either by physisorption or covalent conjugation, resulting in limited ligand loading capacity. In this work, we report the seeded growth of a nucleotide coordinated polymer shell, which can be considered as a special form of adsorption by forming a complete shell. Among all of the tested metal ions, Fe(3+) is the most efficient for this seeded growth. A diverse range of guest molecules, including small organic dyes, proteins, DNA, and gold NPs, can be encapsulated in the shell. All of these molecules were loaded at a much higher capacity compared to that on the naked iron oxide NP core, confirming the advantage of the coordination polymer (CP) shell. In addition, the CP shell provides better guest protein stability compared to that of simple physisorption while retaining guest activity as confirmed by the entrapped glucose oxidase assay. Use of this system as a peroxidase nanozyme and glucose biosensor was demonstrated, detecting glucose as low as 1.4 μM with excellent stability. This work describes a new way to functionalize inorganic materials with a biocompatible shell.

Three-dimensional hierarchical porous PtCu dendrites: A highly efficient peroxidase nanozyme for colorimetric detection of H2O2

Three-dimensional (3D) hierarchical porous PtCu dendrites (HPPtCuDs) as a novel peroxidase nanozyme were fabricated by the formation of 3D hierarchical PtCu dendrites via galvanic replacement, followed by chemical dealloying to selectively dissolve a less noble metal Cu from PtCu alloys. The morphology, structure and composition of HPPtCuDs were characterized in detail. Due to the special 3D porous dendritic structure (geometric effect) and electronic effect, the resulting HPPtCuDs exhibited intrinsic peroxidase-like activity, catalyzing the classical peroxidase substrate 3,3′,5,5′-tetramethyl-benzidine (TMB) by hydrogen peroxide (H2O2). The optimized conditions including pH, temperature, concentrations of both H2O2 and HPPtCuDs were obtained. Kinetic study indicated that the HPPtCuDs showed a stronger affinity for both TMB and H2O2 with lower Michaelis–Menten constant (Km) values, compared with hierarchical PtCu dendrites and monometallic Pt microspheres. Based on the high catalytic activity, the HPPtCuDs was used to construct a colorimetric H2O2 sensor with a wide linear range of 0.3–325μM and a low limit of detection (LOD) of 0.1μM. The LOD was much lower than the H2O2 allowance level of US FDA (0.05wt%, ca. 15μM). With good anti-interference toward various anions and cations and good stability and reusability, this colorimetric H2O2 sensor was successfully applied to the determination of H2O2 in dairy milk products with satisfactory results.