Superior Peroxidase-like Activity Research Articles

Fe-Based Single-Atom Nanozyme with Superior Peroxidase-Mimicking Activity for Enhanced Ultrasensitive Biosensing.

Nanomaterials with intrinsic enzyme-mimicking characteristics, refered to as nanozymes, have become a hot research topic owing to their unique advantages of comparative low cost, high stability and large-scale preparation. Among them, Single-atom nanozymes (SAzymes), as novel nanozymes with abundant atomically dispersed active sites, have caused specific attention in the development of nanozymes for their remarkable catalytic activities, maximum atomic utilization and excellent selectivity, the homogeneous catalytic sites and clear catalytic mechanisms. Herein, a novel single-atom nanozyme based on Fe(III)-doped polydiaminopyridine nanofusiforms (Fe-PDAP SAzyme) was successfully proposed via facile oxidation polymerization strategy. With well-defined coordination structure and abundant Fe-Nx active sites similar to natural metalloproteases, the Fe-PDAP SAzyme exhibits superior peroxidase-like activity by efficiently decomposing H₂O₂ for hydroxyl radical (.OH) species formation. Based on their superior peroxidase-like activity, colorimetric biosensing of H₂O₂ and glucose in vitro was performed by using a typical 3,3,5,5-tetramethylbenzidine through a multienzyme biocatalytic cascade platform, exhibiting the superior specificity and sensitivity. This work not only provides a novel promising SAzyme-based biosensor but also paves an avenue for evaluating enzyme activity and broadens the application of other nanozyme-based biosensors in the fields of biomedical diagnosis.

Vanadium/cobalt oxides–anchored flexible carbon nanofibers with tunable magnetism as recoverable peroxidase-like catalysts

High-efficiency peroxidase-like catalysts that can be easily recycled are desperately needed for the rapid and accurate detection of H2O2. Herein, a novel flexible membrane composed of vanadium/cobalt oxides–anchored carbon (VCoO/C) nanofibers has been purposely designed and fabricated by electrospinning and subsequent carbonization, where there are processing temperature-dependent morphology, composition, and versatile properties. As the carbonization temperature increases from 600°C to 900°C, the saturation magnetization of the as-prepared VCoO/C nanofibers rises gradually. When treated at 750°C under Ar protection, the resultant VCoO/C-750 nanofibers yield superior peroxidase-like catalytic activity toward H2O2 with a low limit of detection of 0.44 μM (signal-to-noise ratio = 3). The combination of magnetic behavior and flexibility enables the effective recovery of catalysts. It is believed that our results will open a new avenue for the controlled preparation of flexible nanofiber materials, which are endowed with multiple functions.

Porous Au@Pt nanoparticles with superior peroxidase-like activity for colorimetric detection of spike protein of SARS-CoV-2

The development of colorimetric assays for rapid and accurate diagnosis of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is of practical importance for point-of-care (POC) testing. Here we report the colorimetric detection of spike (S1) protein of SARS-CoV-2 based on excellent peroxidase-like activity of Au@Pt nanoparticles, with merits of rapidness, easy operation, and high sensitivity. The Au@Pt NPs were fabricated by a facile seed-mediated growth approach, in which spherical Au NPs were premade as seeds, followed by the Pt growth on Au seeds, producing uniform, monodispersed and porous Au@Pt core–shell NPs. The as-obtained Au@Pt NPs showed a remarkable enhancement in the peroxidase-mimic catalysis, which well abided by the typical Michaelis-Menten theory. The enhanced catalysis of Au@Pt NPs was ascribed to the porous nanostructure and formed electron-rich Pt shells, which enabled the catalytic pathway to switch from hydroxyl radical generation to electron transfer process. On a basis of these findings, a colorimetric assay of spike (S1) protein of SARS-CoV-2 was established, with a linear detection range of 10–100 ng mL−1 of protein concentration and a low limit of detection (LOD) of 11 ng mL−1. The work presents a novel strategy for diagnosis of COVID-19 based on metallic nanozyme-catalysis.

A new biomimetic nanozyme of hemin/graphdiyne oxide with superior peroxidase-like activity for colorimetric bioassays.

Graphdiyne oxide (GDYO) is a novel type of two-dimensional carbon allotrope nanomaterial consisting of a large conjugated system and excellent chemical stability. To date, application of GDYO as a nanozyme in biosensing has been rarely reported. In this study, a novel ultrasensitive colorimetric bioassay was constructed using a hemin/GDYO nanocomposite (H/GDYO) as a new nanozyme with superior peroxidase-like activity for the detection of H2O2 and glucose. It was discovered that H/GDYO exhibited 6-fold higher peroxidase-like activity than pure hemin. Catalytic kinetic analysis showed that H/GDYO had a much higher affinity for H2O2 and glucose than that of hemin. The designed colorimetric bioassay displayed excellent sensitivity for H2O2 and glucose detection with a wide linear range of 0.015-0.5 mM and 0.1-10 mM, respectively, while the limit of detection (LOD) was as low as 4.39 μM and 38 μM, respectively. Moreover, it was successfully applied for the analysis of H2O2 in milk and glucose in real human serum samples with acceptable recoveries. Importantly, the developed colorimetric bioassay shows good agreement with the results obtained from a commercial blood glucose meter. We believe that the proposed method could provide a promising prospect for medical diagnosis and biotechnology.

Sweetsop-like α-Fe2O3@CoNi catalyst with superior peroxidase-like activity for sensitive and selective detection of hydroquinone.

Hydroquinone (HQ) is poorly degradable in the ecological environment and is highly toxic to human health even at a low concentration. The colorimetric method has the advantages of low cost and fast analysis, which provides the possibility for simple and rapid detection of HQ. In this work, a new colorimetric method has been developed for HQ detection based on a peroxidase-like catalyst, α-Fe2O3@CoNi. This sweetsop-like α-Fe2O3@CoNi catalyst enables H2O2 to produce hydroxyl (˙OH), leading to the oxidization of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxTMB. In the presence of HQ, the blue oxTMB is reduced to colorless, which allows for colorimetric detection of HQ in water samples. This method has been validated by detecting HQ in water samples with high selectivity, rapid response, broad detection range (0.50 to 30 μM), and low detection limit (0.16 μM).

MoS2-based composite nanozymes with superior peroxidase-like activity for ultrasensitive SERS detection of glucose

An ultrasensitive biosensor with high peroxidase-like catalytic activity and excellent SERS properties is developed based on PANI@MoS2@Fe3O4@Au nanozymes.

Amphiphilic protein controlled synthesis of rice-shaped copper oxide and its substrate dependent enzyme-mimicking activity

Rice-shaped protein–copper oxide hybrid (RSPCO) was prepared by one-pot method in the presence of amphiphilic proteins. The enzyme-mimicking activity of RSPCO depends much on the substrate structure. RSPCO shows superior peroxidase-like activity with 3,3′,5,5′-tetramethylbenzidine (TMB) as a substrate. RSPCO exhibits both peroxidase- and oxidase-like activities with 1,2-diaminobenzene (OPD) as the substrate. RSPCO does not exhibit peroxidase-/oxidase-like activity when using 2,2′-azinobis(3-ethylbenzthiazoline-6-sulfonic acid)diammonium salt (ABTS) as the substrate. Furthermore, pyrogallol (PA)-induced activity switching effect is dependent on the type of enzyme-like activity of nanozyme and the substrate structure. The different effect of PA on the enzyme-like activity of RSPCO attributes mainly to the different affinity of substrates toward RSPCO. PA can significantly inhibit the peroxidase-like activity of RSPCO with TMB used as the substrate. Due to the efficient inhibiting effect, an excellent PA colorimetric sensor with low limit of detection being 15 nM (signal-to-noise ratio of 3) was developed based on RSPCO. With the features of simplification and low cost, protein–copper oxide hybrid nanozymes has the potential application in medial, environmental, and food areas. The present work provides new information about activity–structure relationship of copper oxide nanozyme, which is important for the applications of nanozymes in practice.

Ratiometric Dual Signal-Enhancing-Based Electrochemical Biosensor for Ultrasensitive Kanamycin Detection.

Based on the signal amplification elements of planar VS2/AuNPs nanocomposites and CoFe2O4 nanozyme, we herein developed an electrochemical biosensor for sensitive kanamycin (Kana) quantification. A ratiometric sensing platform was presented by incorporating VS2/AuNPs nanocomposites as a support material with excellent conductivity and high specific surface area, as well as hairpin DNA (hDNA) with complementary hybridization of biotinylated Kana-aptamer. In addition, streptavidin-functionalized CoFe2O4 nanozyme with superior peroxidase-like catalytic activity were immobilized onto the aptasensor, hence the peroxidase-like catalytic reaction could yield amplified electrochemical signals. With the presence of Kana, the aptamer-biorecognition resulted in a quantitative decrease of nanozyme accumulation and an increase of methylene blue response. Under optimal conditions, the electrochemical signal ratio of the aptasensor revealed a linear relation along with the logarithmic concentration of Kana from 1 pM to 1 μM, with the limit of detection reaching to 0.5 pM. Moreover, this aptasensor exhibited excellent precision, as well as high repeatability, hence possessing potentials in real samples and for diverse targets detection by easy replacement of the matched aptamer.

Facile synthesis of CDs@ZIF-8 nanocomposites as excellent peroxidase mimics for colorimetric detection of H2O2 and glutathione

CDs@ZIF-8 nanocomposites are designed and synthesized as nanoenzymes by a novel one-pot synthetic method in solvent-free system, in which ZIF-8 framework protects CDs from the aggregation and quenching, increasing the participation of CDs for catalytic reactions. The embedding of CDs into ZIF-8 matrix is conducted to rapid electron transfer, and their synergetic effect promotes the composite materials to have superior peroxidase-like activity. CDs@ZIF-8 materials have catalyzed the oxidation of a typical colorimetric substrate 3,3′,5,5′-tetramethylbenzydine (TMB) in the presence of H2O2 with the color changes from colorless to blue oxidized TMB (ox-TMB). A colorimetric approach could be established to detect H2O2 and glutathione (GSH) due to the outstanding peroxidase-like activity of CDs@ZIF-8-a. This work gives a feasible strategy for the synthesis of CDs-based composite nanozyme with enhanced catalytic activity and thus broadens the application of CDs@MOFs materials in biological analytical field.

Platinum nanoflowers with peroxidase-like property in a dual immunoassay for dehydroepiandrosterone.

Platinum nanoflowers (PtNFs) were utilized in a competitive enzyme-linked immunosorbent assay (ELISA) and in a lateral flow immunoassay (LFIA) for superior peroxidase-like activity and intense brown color, respectively. PtNFs were linked to the polyclonal antibody (pAb) to form the pAb-PtNFs probes for the dual immunoassay. Based on optimized pAb-PtNF probes, both enzyme-linked immunosorbent assay (PtNFs-ELISA) and lateral flow immunoassay (PtNFs-LFIA) perform very well. The absorbance at 450nm decreases linearly in the DHEA concentration range 2.1 to 118.1ngmL-1, and the limit of detection is 1.3ngmL-1 and theIC50 value is 15.7ngmL-1 of PtNFs-ELISA. The visual cut-off value of PtNFs-LFIA is 10.0ngmL-1. The average recoveries from spiked samples range from 95.0 to 108.9% with a coefficient ofvariation below 12.2%. Excellent recoveries and correlation between the two methods were observed. Furthermore, the designed immunosensors exhibited good selectivity, confirming a broad development prospect in DHEA monitoring. Graphical Abstract.

Natural Polyphenol-Vanadium Oxide Nanozymes for Synergistic Chemodynamic/Photothermal Therapy.

The selection of suitable nanozymes with easy synthesis, tumor specificity, multifunction, and high therapeutics is meaningful for tumor therapy. Herein, a facile one-step assembly approach was employed to successfully prepare a novel kind of natural polyphenol tannic acid (TA) hybrid with mixed valence vanadium oxide nanosheets (TA@VOx NSs). In this system, VOx is assembled with TA through metal-phenolic coordination interaction to both introduce superior peroxidase-like activity and high near infrared (NIR) absorption owing to partial reduction of vanadium from V5+ to V4+ . The presence of mixed valence vanadium oxide in TA@VOx NSs is proved to be the key for the catalytic reaction of hydrogen peroxide (H2 O2 ) to . OH, and the corresponding catalytic mechanism of H2 O2 by TA@VOx NSs is proposed. Benefitting from such peroxidase-like activity of TA@VOx NSs, the overproduced H2 O2 of the tumor microenvironment allows the realization of tumor-specific chemodynamic therapy (CDT). As a valid supplement to CDT, the NIR absorption enables TA@VOx NSs to have NIR light-mediated conversion ability for photothermal therapy (PTT) of cancers. Furthermore, in vitro and in vivo experiments confirmed that TA@VOx NSs can effectively inhibit the growth of tumors by synergistic CDT/PTT. These results offer a promising way to develop novel vanadium oxide-based nanozymes for enhanced synergistic tumor-specific treatment.

A Colorimetric Assay for the Detection of Glucose and H2O2 Based on Cu-Ag/g-C3N4/ZIF Hybrids with Superior Peroxidase Mimetic Activity.

In this work, we report the synthesis of Cu-Ag bimetallic nanopartiles and g-C3N4 nanosheets decorated on zeolitic imidazolate framework-8 (ZIF-8) to form a Cu-Ag/g-C3N4/ZIF hybrid. The hybrid was synthesized and characterized by Transmission electron microscopy (TEM), Fourier transformed infrared (FTIR), the X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The Cu-Ag/g-C3N4/ZIF hybrid has intrinsic peroxidaselike catalytic activity towards the oxidation of TMB in the presence of H2O2. The situ synthesis of Cu-Ag bimetallic nanopartiles on 2D support such as g-C3N4 nanosheets would significantly enhance the peroxidaselike catalytic properties of individual Cu-Ag bimetallic nanopartiles and the g-C3N4 nanosheets. After loading of Cu-Ag bimetallic nanopartiles and g-C3N4 nanosheets on the ZIF-8, the hybrids exhibited superior peroxidaselike catalytic activity and good recyclability. Then, this method was applied for detecting glucose in human serum, owing the significant potential for detection of metabolites with H2O2-generation reactions.

A Hybrid of FeS2 Nanoparticles Encapsulated by Two-Dimensional Carbon Sheets as Excellent Nanozymes for Colorimetric Glucose Detection.

Recently, the development of nanozymes with high catalytic performance is gaining more and more attention due to the ever-growing demands for their practical applications. The elaborate design of its morphology has demonstrated to be an effective approach to improve the performance of these nanozymes. Herein, a hybrid of iron disulfide nanoparticles (FeS2 NPs) encapsulated by two-dimensional (2D) carbon nanosheets (NSs), denoted as FeS2@C NSs, demonstrates both superior peroxidase-like activity and excellent stability. The incorporation of 2D carbon sheets endows the proposed FeS2@C nanozymes with high specific surface area, providing abundant active sites to facilitate the contact with substrates. Moreover, the embedded FeS2 NPs are kept from aggregation due to the encapsulation and confinement of 2D carbon sheets, avoiding the conventional failure of single-component nanozymes. Based on glucose oxidase (GOx) and the elaborately designed FeS2@C nanozymes, a colorimetric method for glucose detection is then developed with excellent simplicity and sensitivity. The detection limit of the sensing platform is as low as 0.19 μM for a glucose assay. More notably, this method can be successfully employed for the glucose assay in some real samples, indicating the great potential of this FeS2@C NS-based nanozymes in the fields of biotechnology and clinical diagnostics.

Core-shell structured Ag-CoO nanoparticles with superior peroxidase-like activity for colorimetric sensing hydrogen peroxide and o-phenylenediamine

Exploring of an efficient and cheap-cost peroxidase mimic is crucial for constructing a colorimetric sensing platform. Herein, a series of Ag-decorated CoO nanoparticles (Ag-CoO NPs) were synthesized by a facile one-pot solvothermal strategy and followed by heat treatment. The compositions and morphologies of the as-prepared catalysts were characterized by XRD, N2-adsorption/desorption, SEM, TEM, XPS, UV–vis diffuse reflectance and transient photocurrent techniques. The core-shell structured 0.10Ag-CoO NPs (molar ratio of AgNO3/Co(NO3)2 = 0.10) with high dispersion possess large specific surface area (156.8 cm2 g−1) and rich mesoporous structure, thus providing more catalytic active sites. Suitable Ag decoration not only increases the surface active oxygen species and strengthens the visible light respond but also improves the separation of photo-generated electron–hole pairs of 0.10Ag-CoO NPs. As a result, 0.10Ag-CoO NPs exhibit superior peroxidase-like activity for 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation in the presence of H2O2 compared to pure CoO NPs and the other nanoparticles. Then a sensitive and selective colorimetric sensing platform was constructed for detecting hydrogen peroxide and o-phenylenediamine. Finally, the possible catalytic mechanism was also proposed here.

One-Dimensional Synergistic Core-Shell Nanozymes with Superior Peroxidase-like Activity for Ultrasensitive Colorimetric Detection of Blood Cholesterol.

In this paper, a simple and green strategy was proposed to fabricate one-dimensional core-shell Fe3O4@C/Ni nanocomposites. The rationally designed hybrid nanostructures notably exhibited an extremely excellent peroxidase-mimicking property, arising from the synergetic effects of Fe3O4, carbon, and Ni nanoparticles, along with the hollow and hierarchically porous nanostructures. Based upon the outstanding peroxidase-like activity and cholesterol oxidase cascade reaction, a label-free, ultrasensitive, and highly selective colorimetric assay for cholesterol determination has been developed. Under the optimized conditions, the colorimetric biosensor demonstrated a linear response to cholesterol ranging from 5 to 200 μM, with a relatively low detection limit of 0.17 μM. More importantly, cholesterol determination as low as 5 μM could be directly distinguished with the naked eye. In addition, we successfully determined the total cholesterol content in human serum samples with satisfactory accuracy and good precision. The Fe3O4@C/Ni nanocatalyst-based colorimetric biosensor provides great potential in point-of-care testing in disease diagnosis.

Cadmium cobaltite nanosheets synthesized in basic deep eutectic solvents with oxidase-like, peroxidase-like, and catalase-like activities and application inthe colorimetric assay of glucose.

Cadmium cobaltite (CdCo2O4) nanosheets were ultra-fast synthesized based on a new basic deep eutectic solvent (DES) which served simultaneouslyas reactant, solvents, and template. Interestingly, the nanosheets were found to exhibit triple-enzyme mimetic activities including oxidase-like activity, peroxidase-like activity, and catalase-like activity. Their catalytic activity followed the typical Michaelis-Menten kinetics, and high affinity for H2O2 and TMB was observed. Based on the superior peroxidase-like catalytic activity of CdCo2O4 nanosheets, a highly sensitive and selective colorimetric strategy for the determination of glucose was established. Under optimized conditions, the absorbance at 652nm increases linearly in the 0.5 to 100μM concentration range, and the limit of detection is 0.13μM (S/N= 3). Finally, the method was successfully used for determination of glucose in serum samples. Graphical abstract The CdCo2O4 nanosheets were ultra-fast synthesized with a basic deep eutectic solvent, and this nanomaterial exhibited triple-enzyme mimetic activities: oxidase-like activity, peroxidase-like activity, and catalase-like activity. Based on the peroxidase-like activity, a highly sensitive and selective glucose colorimetric sensor was established.

2D Graphene Oxide/Fe-MOF Nanozyme Nest with Superior Peroxidase-Like Activity and Its Application for Detection of Woodsmoke Exposure Biomarker.

Emerging nanomaterials such as nanozymes have recently been applied for the immunoassay-based detection of biomarkers. However, the inferior catalytic activity and low water solubility of nanozymes remain as the major limitations compared to natural enzymes. To overcome these limitations, we successfully synthesized a superior nanozyme with a structure of enriched 2D catalytic interface, namely Nanozyme Nest, which was composed of Fe-based metal-organic frameworks (Fe-MOF) and graphene oxide (GO). Then, we applied it in an ultrasensitive enzyme-linked immunosorbent assay (ELISA) for the detection of benzo[a]pyrene-7,8-diol 9,10-epoxide-DNA adduct (BPDE-DNA), which is a metabolite of benzo[a]pyrene (BP) and used as a typical biomarker of woodsmoke exposure in human blood. The Nanozyme Nest features amplified peroxidase-like catalytic ability from graphene and Fe-MOF due to their large surface area and abundant active sites. By using the proposed Nanozyme Nest-based ultrasensitive ELISA, the BPDE-DNA could be detected at a level as low as 0.268 ng/mL, and the obtained sensitivity was much higher than most of the widely used methods. Our work provides a novel strategy to design ultrasensitive immunosensors with advantages of amplified catalytic activity and improved water solubility compared to classic nanozymes. This illustrates the promising applications of the Nanozyme Nest-based immunosensors in point-of-care settings to conveniently detect exposures and diagnose diseases.

Cu-Doped Carbon Dots as Catalysts for the Chemiluminescence Detection of Glucose.

Development of metal-doped carbon dots (CDs) to effectively modulate their electronic properties and surface chemical reactivities is still in its early stage. In this paper, a facile solid-phase synthesis strategy was developed to synthesize Cu-doped CDs (Cu-CDs) using citric acid as the carbon source and Cu(NO3)2·3H2O as the dopant, respectively. The as-prepared Cu-CDs exhibited superior peroxidase-like activity to horseradish peroxidase and were stable under a wide range of pH and temperatures. Consequently, the Cu-CD-based chemiluminescence sensing was applied to sensitively detect glucose with a low detection limit of 0.32 μM, and the recoveries and the relative standard deviation of the serum sample are 87.2–112.2 and 8.16% (n = 6), respectively. Notably, the proposed chemiluminescence sensing was also successfully applied for label-free detection of glucose in complex biological samples, which envisioned its potential applications in clinical diagnosis and other analytical assays.

Single-Atom Nanozyme Based on Nanoengineered Fe-N-C Catalyst with Superior Peroxidase-Like Activity for Ultrasensitive Bioassays.

Single-atom catalysts are becoming a hot research topic owing to their unique characteristics of maximum specific activity and atomic utilization. Herein, a new single-atom nanozyme (SAN) based on single Fe atoms anchored on N-doped carbons supported on carbon nanotube (CNT/FeNC) is proposed. The CNT/FeNC with robust atomic Fe-Nx moieties is synthesised, showing superior peroxidase-like activity. Furthermore, the CNT/FeNC is used as the signal element in a series of paper-based bioassays for ultrasensitive detection of H2 O2 , glucose, and ascorbic acid. The SAN provides a new type of signal element for developing various biosensing techniques.

Atomic layer deposition-assisted growth of CuAl LDH on carbon fiber as a peroxidase mimic for colorimetric determination of H2O2 and glucose

An atomic-layer-deposited Al2O3-induced LDH growth strategy was proposed to prepare carbon fiber-supported ultrathin CuAl LDH nanosheets (CF@CuAl-LDH). The CF@CuAl-LDH exhibited superior peroxidase-like catalytic activity.