Peroxidase-like Nanozyme Research Articles

Au@MOFs used as peroxidase-like catalytic nanozyme for bacterial infected wound healing through bacterial membranes disruption and protein leakage promotion

Bacterial biofilms often hinder the healing of infected chronic wounds. Hence, it is significant to explore ways to destroy bacterial biofilms. In this work, a photothermal therapy strategy of designing Au clusters modified ZIF-8 MOFs (Au@ZIF-8) as peroxidase-like catalytic nanozyme was proposed for bacterial infected wound healing. Under near-infrared laser (NIR), the prepared Au@ZIF-8 present enhanced peroxidase-like activity and excellent photothermal response properties. Au@ZIF-8 achieved bacterial membrane disruption rate of 66.3% and MRSA clearance rate up to 97%. Au@ZIF-8 also catalyzed endogenous H2O2 to OH and achieved almost 97.4% healing rate in animal experiments. The prepared Au@ZIF-8 with peroxidase-like catalytic nanozyme properties has great potential in the treatment of infected diabetic wounds through bacterial membranes disruption and protein leakage promotion.

Citrate-functionalized osmium nanoparticles with peroxidase-like specific activity for highly efficient degradation of phenolic pollutants

Platinum group metals-based nanomaterials have shown promise as enzyme mimics, and attracted much attention in the fields of chemical catalysis, biosensor, therapy and pollutants degradation. Surprisingly, only a few works exist on the exploration of osmium-based nanozymes, and the catalytic activities and applicable potentials thereof have not been comprehensively understood. Herein, we prepared a kind of citrate-functionalized osmium nanoparticles (Os-citrate NPs) by one-pot synthesis strategy. The obtained Os-citrate NPs can boost hydrogen peroxide (H2O2) to produce hydroxyl radical (•OH), enabling it to serve as a peroxidase mimic. Steady-state kinetics revealed that Os-citrate NPs is rather potent and peroxidase-like specific nanozyme. Doping a certain amount of osmium oxides (OsO2) in the surface of Os-citrate NPs can greatly improve the production of •OH from H2O2, enhancing the peroxidase-like specific activity. We applied this Os-citrate catalyst in advanced oxidative degradation of phenolic pollutants. In a wide pH range of 2.0–10, 4-nitrophenol could be fast degraded by the combination of H2O2 with Os-citrate NPs. As a proof-of-concept, the Os-citrate nanozyme was successfully employed in highly efficient degradation of phenolic pollutants. To the best of our knowledge, this is the first report on the application of Os-based peroxidase-like nanozymes in highly efficient degradation of organic pollutants.

Cobalt-based zeolitic imidazole framework incorporated with well-dispersed bimetallic nanoparticles/ions as a multifunctional nanozyme for the degradation of environmental pollutants and discrimination of various phenolic substances

Several strategies, such as increasing catalytic active sites, doping another element, and designing hybrids, have been used to enhance the catalytic efficiency of the nanozyme for the efficient degradation of pollutants, sensitive analysis, and effective disease therapy. However, multifunctional nanozyme catalysts from a single MOF precursor with improved catalytic activity lack systematic research. Here, we have developed six nanozyme composites from a cobalt-based zeolitic imidazole framework (ZIF-67) as a precursor by doping metal ions (Ni2+ or Cu2+, or Fe2+) and subsequent high-temperature treatment. It is found that three kinds of metal ions-doped ZIF-67 and their corresponding high-temperature pyrolysis exhibit three kinds of catalytic activity including peroxidase-like, oxidase-like, and pollutant-reduced degradation nanozyme. Firstly, the degradation rate of pollutant substrates is increased by more than 13.3 times by doping metal ions (Ni2+ or Cu2+, or Fe2+) in ZIF-67. Moreover, a more than 96.3-fold enhancement is achieved by integrating doped-metal ions and pyrolysis of ZIF-67. Secondly, the oxidase-like activity of decorated-metal ions (Ni2+ or Cu2+, or Fe2+) ZIF-67 is enhanced by more than 300%. Thirdly, it is found that the reactive oxygen intermediate species (ROS) including singlet oxygen (1O2) and superoxide anion (•O2–) are produced by the oxidase-like reaction. Finally, we have proposed a facile and high-performance sensor array for colorimetric quantification and discrimination of nine phenolic pollutants and five biological molecules at no less than 2.0 μM by employing three decorated-metal ions ZIF-67 composite as the oxidase-like nanozyme. Ultimately, the colorimetric array sensor has great potential application prospects in monitoring environmental phenolic pollutants and disease diagnosis.

Platinum-Nickel Nanoparticles with Enhanced Oxidase-like Activity for Total Antioxidant Capacity Bioassay.

While great progress in nanozyme-enabled analytical chemistry has been made, most current nanozyme-based biosensing platforms are based on peroxidase-like nanozymes. However, peroxidase-like nanozymes with multienzymatic activities can influence the detection sensitivity and accuracy, while the use of unstable hydrogen peroxide (H2O2) in a peroxidase-like catalytic reaction may result in the reproducibility challenge of sensing signals. We envision that constructing biosensing systems by using oxidase-like nanozymes can address these limitations. Herein, we reported that platinum-nickel nanoparticles (Pt-Ni NPs) with Pt-rich shells and Ni-rich cores possessed high oxidase-like catalytic efficiency, exhibiting a 2.18-fold higher maximal reaction velocity (vmax) than initial pure Pt NPs. The oxidase-like Pt-Ni NPs were applied to develop a colorimetric assay for the determination of total antioxidant capacity (TAC). The antioxidant levels of four bioactive small molecules, two antioxidant nanomaterials, and three cells were successfully measured. Our work not only provides new insights for preparing highly active oxidase-like nanozymes but also manifests their applications for TAC analysis.

A peroxidase-like magneto-gold nanozyme AuNC@Fe3O4 with photothermal effect for induced cell apoptosis of hepatocellular carcinoma cells in vitro.

Hepatocellular carcinoma (HCC) is one of the most commonly diagnosed and malignant cancers worldwide. Conventional therapy strategies may not completely eradicate the tumor and may cause side effects during treatment. Nano-catalytic therapy, as a novel strategy, has attracted a great deal of attention. This study aimed to synthesize a multifunctional magneto-gold nanozyme AuNC@Fe3O4 and evaluate its anti-cancer potential in HepG2 cells in vitro. The characteristics of AuNC@Fe3O4 were assessed using a transmission electron microscope, dynamic light scattering, and energy-dispersive X-ray. The photothermal performance and peroxidase (POD)-like activity of AuNC@Fe3O4 were detected, using thermal camera and ultraviolet-visible spectrophotometer, respectively. The anti-cancer potential of AuNC@Fe3O4 was examined using cell counting kit-8, live/dead cell staining, and apoptosis analysis. Further research on HepG2 cells included the detection of intracellular reactive oxygen species (ROS) and lysosomal impairment. We observed that the AuNC@Fe3O4 had a small size, good photothermal conversion efficiency and high POD-like activity, and also inhibited cell proliferation and enhanced cell apoptotic ability in HepG2 cells. Furthermore, the AuNC@Fe3O4 enhanced ROS production and lysosomal impairment via the synergistic effect of photothermal and nano-catalytic therapies, which induced cell death or apoptosis. Thus, the magneto-gold nanozyme AuNC@Fe3O4 may offer a potential anti-cancer strategy for HCC.

Peroxidase-like Nanozymes for Point-of-Care SERS Sensing and Wound Healing.

The emergence of nanozymes provides a potential method for combating multidrug-resistant bacteria resulted from the abuse of antibiotics. However, in nanozyme-catalyzed systems, few studies have addressed the actual hydrogen peroxide (H2O2) level involved in sterilization. Herein, we designed a high-efficiency peroxidase-mimicking nanozyme with surface-enhanced Raman scattering (SERS) property by assembling gold nanoparticles on single-layer Cu2+-C3N4 (AuNP-Cu2+-C3N4). The nanozyme effectively converts the low-active Raman reporter 3,3',5,5'-tetramethylbenzidine (TMB) into its oxidized form with H2O2, resulting in SERS signal changes, thereby achieving highly sensitive quantification of H2O2 with limit of detection as low as 0.60 μM. More importantly, the nanozyme can specifically catalyze H2O2 into antibacterial hydroxyl radicals. In vitro and in vivo evaluations demonstrate the remarkable antibacterial efficacy of the nanozyme/H2O2 combination against Staphylococcus aureus (up to 99.9%), which could promote wound healing in mice and allow point-of-care monitoring the amount of H2O2 participated in effective sterilization. This study not only displays great potential in combining multiple functionalities of nanomaterials for versatile bioassays but also provides a promising approach to design nanozymes for biomedical and catalytic applications.

A Single Aptamer-Dependent Sandwich-Type Biosensor for the Colorimetric Detection of Cancer Cells via Direct Coordinately Binding of Bare Bimetallic Metal-Organic Framework-Based Nanozymes.

A typical colorimetric sandwich-type sensor relies on dual antibodies/aptamers to specifically visualize the targets. The requirement of dual antibodies/aptamers and low signal intensity inevitably increases the design difficulty and compromises the sensing sensitivity. In this work, a novel sandwich-type aptasensor was developed using single aptamer-functionalized magnetic nanoparticles as a specific recognition unit to target cancer cells and a bimetallic metal-organic frameworks (MOFs)-based nanozymes as a colorimetric signal amplification unit. The well-defined crystalline structure of UIO-66 MOFs enabled the introduction of Fe/Zr bimetal nodes, which possessed integrated properties of the peroxidase-like nanozyme activity and direct coordinately binding to the cell surface. Such a novel construction strategy of sandwich-type aptasensors achieved simple, sensitive, and specific detection of the target cancer cells, which will inspire the development of biosensors.

Nanozymes from Cu(II) Metal–Organic Gel and Melamine for Highly Active Peroxidase-Like Activity to Detect Alkaline Phosphatase

Enzyme-like catalytic activity and efficiency of carbon-based nanomaterials are closely linked to their size, heteroatom composition, and structure, and hence the heteroatom regulation needs to be further explored. In this work, a simple and efficient strategy was proposed to develop Cu-doped 2D carbon material C3N4 (Cu-C3N4-550) with excellent catalytic performance by pyrolyzing precursors of Cu(II) metal–organic gel (MOG) and melamine directly. Due to its sufficient metal active sites and adequate specific surface areas, the as-prepared Cu-C3N4-550 was endowed with excellent peroxidase-like activity to promote the oxidation of 3,3′,5,5′-tetramethylbenzidine owing to the generation of •OH in the catalytic reaction. It was amazing to find that the peroxidase mimic activity of the prepared Cu-C3N4-550 has enhanced 32.3-fold compared with bare C3N4. High peroxidase-like activity of Cu-C3N4-550 was influenced severely by the addition of antioxidant ascorbic acid (AA), alkaline phosphatase (ALP) as a typical hydrolase could catalyze substrate 2-phospho-l-ascorbic acid into AA, while AA was capable of capturing •OH generated from the catalytic reaction of Cu-C3N4-550. Hence, a sensitive, selective, and colorimetric method for the detection of ALP was established, the linear concentration of ALP in this colorimetric sensor from 0.4 to 20 U/L was acquired with a low detection limit of 0.32 U/L. This work not only provides ideas for designing enhanced peroxidase-like activity nanozymes in practical biological analysis but also broadens the MOG derivatives and carbon-based nanomaterials in colorimetric applications.

Nanozyme: a rising star for cancer therapy.

In recent years, nanozymes have attracted enormous attention due to their effectiveness in promoting various catalytic reactions. To date, thousands of nanozymes have been discovered, including oxidase-like nanozymes, peroxidase-like nanozymes, and catalase-like nanozymes, covering noble metal, transition metal, and carbon nanomaterials. These nanozymes have been widely applied in various fields, including environmental protection, biosensing and nanomedicine. There are many reviews about this rising star being used in analytical chemistry. However, few works about nanozymes were related to cancer therapy. In this study, we comprehensively summarize the latest research advances on the strategies for cancer therapy based on different nanozymes. With traditional cancer treatment (including chemotherapy, radiotherapy, phototherapy), nanozyme catalytic therapy exhibited a synergistic effect for limiting the growth of tumors. Opportunities and trends for nanozymes in future cancer therapy are also discussed.

Organic compound-based nanozymes for agricultural herbicide detection.

Nanozymes are increasingly being used for agricultural applications, but their adoption is limited as they are generally considered toxic, have low cost-effectiveness, and pose complexity of fabrication. In this study, an organic compound-based, peroxidase-like nanozyme (OC nanozyme) was developed for use in the agricultural environment. This nanozyme was synthesized through a self-assembled one-pot particle synthesis process, interacting with urea and the metal ion to form a homogenous nanoparticle containing partially mimicked cofactors (Fe-N) of the natural enzyme. The OC nanozyme exhibited decent kinetic properties (H2O2/Km:0.056 mM and Vmax:2.19 μM s-1) and pH stability. The OC nanozyme was successfully used to detect glyphosate via integrated colorimetric assay, with a good limit of detection (LOD) of at least 0.001 ng mL-1. The authors envision that this agricultural-friendly OC nanozyme holds great potential for a wide range of agricultural applications.

Glutathione peroxidase-like nanozymes: mechanism, classification, and bioapplication.

The field of nanozymes is developing rapidly. In particular, glutathione peroxidase (GPx)-like nanozymes, which catalytically reduce H2O2/organic hydroperoxides to H2O/alcohols, have attracted considerable attention. GPx-like nanozymes are powerful antioxidant enzymes known to combat oxidative stress. They have broad applications, including cytoprotection, anti-inflammation, neuroprotection, tumor therapy, and anti-aging. Although much progress has been made, GPx-like nanozymes have not been well discussed or fully reviewed as other nanozymes. This review aims to summarize recent advances on GPx-like nanozymes from the vantage point of mechanism, classification, and bioapplication. Future prospects for advancing their design and application are also discussed.

Self-propelled Janus magnetic micromotors as peroxidase-like nanozyme for colorimetric detection and removal of hydroquinone

A Janus micromotor-assisted dual-function platform through a novel and facile method was designed and fabricated for sensitive detection and rapid degradation of hydroquinone in water.

Gold nanoparticle-decorated MoSe2 nanosheets as highly effective peroxidase-like nanozymes for total antioxidant capacity assay

Gold nanoparticle-decorated MoSe2 nanosheets as highly effective peroxidase-like nanozymes for total antioxidant capacity assay

CuBi bimetallic aerogel as peroxidase-like nanozyme for total antioxidant capacity colorimetric detection

Metal aerogel with porous structure and interlocking pore channel can provide abundant active sites to boost the peroxidase (POD)-like activity for high-performance colorimetric analysis of food quality. Herein, CuBi bimetallic aerogels with different atomic ratio (Cu1Bi9, Cu5Bi5 and Cu9Bi1) were fabricated by a facile one-step reduction strategy, and the POD-like activity of the synthesized CuBi bimetallic aerogels was studied. The specific activity of Cu9Bi1 aerogel was significantly enhanced due to the Bi-doping strategy. Through comparing the Km values we find that CuBi bimetallic aerogel can be used as a cheap alternative to equivalent noble metal materials for biosensor applications. Then, the optimized nanozyme was exploited to establish a colorimetric method for the total antioxidant capacity (TAC) by utilizing ascorbic acid (AA) as a representative antioxidant model. The linear range and limit of detection (LOD) were determined to be 300–900 μM and 59.4 μM, respectively, the wide detection range simplifies sample pre-treatment steps. Additionally, the method also demonstrated good feasibility for the TAC of food samples. The current study expands new fields for the application of metal aerogels and successfully developed macroscopic nanozymes with a convenient application, facile preparation and low cost.

Artificial metalloenzyme with peroxidase-like activity based on periodic mesoporous organosilica with ionic-liquid framework

Artificial enzymes were developed as alternatives to natural enzymes. Considering the unique characteristics of periodic mesoporous organosilica (PMO) materials, a rational design approach was investigated to simulate the coordination sphere around the iron active center in natural horseradish peroxidase (HRP) and fabricate a new peroxidase-like nanozyme. Well-ordered mesoscopic structure, high surface area, tunable pore size, high thermal-hydrothermal stability, and facile surface functionalization are unique properties of PMOs which allow them be potential candidate for enzyme mimic catalysis. In the present study, a monofunctional PMO with ionic-liquid framework (PMO-IL) was prepared as a support to incorporate the iron protoporphyrin IX hemin. The interior surface of mesochannels were also modified by imidazole functional groups. The synthetic peroxidase-like nanomaterial was fully characterized using several techniques such as N2 adsorption-desorption analysis, Thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) spectroscopy, powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray analysis (EDAX). Peroxidase-like activity of the current nanomaterial was evaluated using 2,2′-Azinobis [3-ethylbenzothiazoline-6-sulfonic acid]-diammonium salt (ABTS) in the presence of hydrogen peroxide in neutral pH condition. Michaelis-Menten kinetic parameters indicated enhanced affinity toward substrate. Results imply that the biomimetic pathways can be developed to achieve a new generation of nanozymes with excellent thermal stability and long-term storage stability which are promising as peroxidase mimics for various applications.

Platinum nanoparticles confined in metal-organic frameworks as excellent peroxidase-like nanozymes for detection of uric acid.

High levels of uric acid (UA) in humans can cause a range of diseases, and traditional assays that rely on uric acid enzymes to break down uric acid are limited by the inherent deficiencies of natural enzymes. Fortunately, the rapid development of nanozymes in recent years is expected to solve the above-mentioned problems. Hence, we used a host-guest strategy to synthesize a platinum nanoparticle confined in a metal-organic framework (Pt NPs@ZIF) that can sensitively detect UA levels in human serum. Unlike previously reported free radical-catalyzed oxidation systems, its unique electron transfer mechanism confers excellent peroxidase-like activity to Pt NPs@ZIF. In addition, UA can selectively inhibit the chromogenic reaction of TMB, thus reducing the absorbance of the system. Therefore, using the peroxidase-like activity of Pt NPs@ZIF and using TMB as a chromogenic substrate, UA can be detected directly without relying on natural enzymes. The results showed a relatively wide detection range (10-1000μM) and a low detection limit (0.2μM). Satisfactory results were also obtained for UA in human serum. This study with simple operation and rapid detection offers a promising method for efficiently detecting UA in serum.

Hollow NiCo@C Nanozyme-Embedded Paper-Based Colorimetric Aptasensor for Highly Sensitive Antibiotic Detection on a Smartphone Platform.

Antibiotic residues in the environment and in foods pose a serious threat to ecosystems and human health. Developing sensitive and on-site detection methods is therefore in high demand. In this work, a portable paper-based colorimetric sensor with a smartphone platform with an ultrahigh sensitivity has been designed for on-site and quantitative analysis of antibiotic residues based on aptamer-regulated nanozyme activity. The developed excellent peroxidase-like nanozymes, carbon-protected NiCo bimetal oxides with a unique hollow nanocage structure (NiCo@C HCs), could effectively catalyze the oxidation of chromogenic substrates by H2O2. Once bound to a specific aptamer, the enzyme-mimicking activity of NiCo@C HCs is obviously inhibited as a result of the masking of active sites but could be restored via the target-aptamer recognition. Herein, the aptamer-modified NiCo@C HCs are embedded on paper pieces to construct paper-based biochips for visual detection. Meanwhile, a smartphone platform is integrated for the signal readout. Using enrofloxacin (ENR) as an analyte model, the proposed paper-based analysis platform shows a reliable and sensitive detection of ENR with an ultralow detection limit of 0.029 ng/mL. The platform also works well in various real samples. This analysis method is facile in design, showing a great application potential for on-site and mass screening of antibiotic residues in the environment and in foods.

Foldable paper microfluidic device based on single iron site-containing hydrogel nanozyme for efficient glucose biosensing

Peroxidase-mimicking nanozymes have been extensively studied, but their real utilization is limited by their working conditions limited to acidic pH, which makes it difficult to couple with oxidative enzymes operating at near-neutral pH. Here, we have developed a foldable paper microfluidic device that enables a highly convenient cascade reaction between peroxidase-mimicking nanozymes and oxidative enzymes to visually identify the target molecules. A single-atom iron-site-containing poly-γ-glutamic acid/chitosan hydrogel nanoparticle (PGA-Fe/CS NP) was developed, as a model peroxidase-like nanozyme, via rapid ionic gelation. Glucose oxidase (GOx) was used as a model oxidative enzyme. The paper device was constructed by simple wax-printing, including two parts with a foldable configuration: the first is for glucose oxidation under neutral pH and the second is for H2O2 reduction to produce a colorimetric signal under acidic pH. By dropping the sample solution in the first part, the device allowed efficient glucose oxidation by the immobilized GOx at neutral pH. On merely folding the device, the produced H2O2 from the glucose oxidation easily transfers to the second part of the device where PGA-Fe/CS NP was immobilized, inducing the peroxidase-like catalytic reaction at acidic pH. Using the foldable paper microfluidic device, the target glucose was successfully determined with excellent selectivity, sensitivity, stability, and reliability, using an image acquired by a smartphone. Since any oxidative enzymes could be incorporated into the device with the peroxidase-like PGA-Fe/CS NP, we expect that the foldable paper microfluidic device, which conveniently allows the cascade reaction under different pH environments, would be highly beneficial for the detection of various clinically important target molecules, thus laying the groundwork for future biosensing applications of nanozymes in point-of-care testing environments.

Biosensor Based on Peroxidase-Mimetic Nanozyme and Lactate Oxidase for Accurate L-Lactate Analysis in Beverages

Precision analysis of the key biological metabolites such as L-lactate has great practical importance for many technological processes in food technology, including beverage production. Here we describe a new, highly selective, and sensitive biosensor for accurate L-lactate assay based on a combination of peroxidase-mimetic nanozymes with microbial lactate oxidase (LOx) immobilized onto the surface of a graphite-rod electrode (GE). The peroxidase-like nanozymes were synthesized using the debris of carbon microfibers (CFs) functionalized with hemin (H) and modified with gold nanoparticles (AuNPs) or platinum microparticles (PtMPs). The nanozyme formed with PtMPs as well as corresponding bioelectrodes based on it (LOx-CF-H-PtMPs/GE) is characterized by preferable catalytic and operational characteristics, so it was selected for the analysis of L-lactate content in real samples of grape must and red wine. The results of the L-lactate analysis obtained by the developed biosensors are highly correlated with a very selective spectrophotometric approach used as a reference. The developed biosensor, due to its high selectivity and sensitivity, is very prospective not only for the beverage industry and food technology, but also for clinical diagnostics and medicine, as well as in other applications where the accurate analysis of L-lactate is highly important.

Surface-Mediated Production of Complexed •OH Radicals and FeO Species as a Mechanism for Iron Oxide Peroxidase-Like Nanozymes.

Fe3 O4 nanoparticles (NPs) with intrinsic peroxidase-like properties have attracted significant interest, although limitedinformation is available on the definite catalytic mechanism. Here, it is shown that both complexed hydroxyl radicals (•OH) and high-valent FeO species are attributed primarily to the peroxidase-like catalytic activity of Fe3 O4 NPs under acid conditions rather than only being caused by free •OH radicals generated through the iron-driven Fenton/Haber-Weiss reactions as previously thought. The low energy barrier of OO bond dissociation of H2 O2 /•OOH (0.14eV) and the high oxidation activity of surface FeO (0eV) due to the reduced state of Fe on the surface of Fe3 O4 NPs thermodynamically favor both the •OH and FeO pathways. By contrast, high-valent FeO species are the key intermediates in the catalytic cycles of natural peroxidase enzymes. Moreover, it is demonstrated that the enzyme-like activity of Fe3 O4 NPs can be rationally regulated by modulating the size, surface structure, and valence of active metal atoms in the light of this newly proposed nanozyme catalytic mechanism.