Peroxidase-like Catalyst Research Articles

Temperature-modulated porous gadolinium micro-networks with hyperchrome-enhanced fluorescence effect

Porous gadolinium micro-networks with hyperchrome-enhanced fluorescence effect are prepared for white light-emitting diodes and highly-efficient peroxidase-like catalyst. • Gd-MNs with hyperchrome-enhanced fluorescence are prepared by a facile one-pot hydrothermal method. • Porous Gd-MNs with tunable porosity can be obtained by controlling the reaction temperature. • Porous Gd-MNs as the carrier can be well used for white light-emitting diodes and peroxidase-like catalyst. Porous and luminescent functional materials having well-controlled morphology are crucial in the field of adsorption, catalysis, and drug release. Herein, we propose the mechanism of hyperchrome-enhanced fluorescence (HEF) for the synthesis of highly fluorescent gadolinium micro-networks (Gd-MNs) via a facile one-pot hydrothermal treatment of almost non-luminescent Gd 3+ ions / citric acid (Gd 3+ /CA) complexes. It is found that after high-temperature polymerization, a strong π-π* transition occurs in the Gd-MNs, which significantly enhances the absorption of light. So, our proposed HEF effect as a new photoactivation strategy can efficiently improve the fluorescence (FL) emission of optical materials by creating a large π-conjugated structure. Surprisingly, the FL of Gd-MNs is 152 times higher compared to that of Gd 3+ /CA complexes. In particular, porous Gd-MNs (P-Gd-MNs) having tunable porosity can be obtained by changing the reaction temperature, as the formation of the porous structure is strongly dependent on the release of H 2 O molecules, coordinated with Gd 3+ ions. Because of their porous structure and good FL properties, P-Gd-MNs is an ideal material for white light-emitting diodes (WLEDs) with adjustable correlation color temperature, by embedding fluorescent carbon dots into their pores. Besides, P-Gd-MNs can also be transformed into a peroxidase-like catalyst by directly reducing the Cu 2+ ions of the porous surface. Moreover, Cu coated P-Gd-MNs can also be used for catalysing the degradation of rhodamine 6G dye with a degradation efficiency of about 100%. Hence, the facile synthesis of P-Gd-MNs opens new avenues for its potential applications in WLEDs fabrication and biocatalysis.

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).

Temperature-responsive mesoporous silica nanoreactor with polymer gatings immobilized surface via a ‘grafting-to’ approach as peroxidase-like catalyst

Abstract An efficient gold decorated mesoporous silica/polymer hybrid nanoreactor was prepared for catalytic applications. The Huisgen cyclo-addition method was used to immobilize poly(2-(dimethylamino)ethyl methacrylate (PDMAEMA) gatings on the surface of the mesoporous silica using a ‘grafting-to’ approach. The catalyst particles exhibited well-ordered mesoporous structural integrity with well-dispersed gold nanoparticles showing resonance plasma absorption. The catalyst exhibited efficient peroxidase like activity for the oxidation of 3,3,5,5-tetramethylbenzidine in the presence of H2O2, which was found to be in consistent with the standard Michaelis-Menten kinetics. The change in the catalytic activity with temperature was evaluated using 4-nitrophenol reduction as the model reaction. The catalyst showed nonlinear variation of the rate constants with temperature. A sharp decrease in the rate constant was observed above 35 °C due to the thermodynamic volume phase transition of the grafted PDMAEMA chains. In contrast, a typical Arrhenius-type dependence of the rate constant on temperature was observed above and below the transition temperature of PDMAEMA.

Liquid-Phase Exfoliation and Functionalization of MoS2 Nanosheets for Effective Antibacterial Application.

A lysozyme (Lys)-assisted liquid-phase exfoliation technique was designed to synthesize MoS2 nanosheets (MoS2 -Lys NSs). As a novel nanozyme antibacterial agent with high peroxidase-like catalyst activity, MoS2 -Lys NSs showed good antibacterial efficacy against both Gram-negative ampicillin-resistant Escherichia coli (Ampr E. coli) and Gram-positive Bacillus subtilis. A possible antibacterial mechanism is also proposed. This work provides an effective antibacterial strategy based on the MoS2 -Lys NSs antibacterial agent.

Highly dispersed Pt nanoparticles on ultrasmall EMT zeolite: A peroxidase-mimic nanoenzyme for detection of H2O2 or glucose

In past decade, Pt-based nanomaterials as peroxidase mimics have attracted much attention for H2O2 and glucose detection. However, easy aggregation of Pt nanoparticles (Pt NPs) greatly decreases their peroxidase-like activity. In this work, novel Pt/EMT nanocomposites were prepared by uniformly loading Pt NPs (5–8 nm) onto the support of ultrasmall EMT zeolite (15–20 nm), a kind of low-silica microporous aluminosilicate material. The hybrid Pt/EMT nanomaterials could be well dispersed in water to form a homogeneous suspension, and were then utilized as a superior peroxidase-like catalyst for oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2). The optimal catalyst of 2.6Pt/EMT nanocomposite exhibited excellent catalytic performance toward H2O2 and TMB than natural enzyme of horseradish peroxidase (HRP) by using a steady-state kinetic analysis based on the typical Michaelis-Menten kinetics theory. The peroxidase-like catalyst showed a promising activity in a wide pH and temperature range as well as the long-term stability. A facile and reliable colorimetric assay based on the peroxidase mimic of Pt/EMT nanocomposite was constructed for precise detection of H2O2 and glucose in a wide linear range, with low limits of detection of 1.1 μM and 13.2 μM, respectively. Due to high selectivity to glucose against other sugars on the catalyst, the method was demonstrated to accurately measure the concentration of glucose in real samples including human blood serum and fruit juices, indicating a potential application of the Pt/EMT nanocomposites as a robust peroxidase mimic and a reliable biosensor in the fields of clinical diagnosis, pharmaceutical, food research and so on.

Zinc-Doped Mesoporous Graphitic Carbon Nitride for Colorimetric Detection of Hydrogen Peroxide

Recently, graphitic carbon nitride (g-C3N4) has been explored as a peroxidase-like catalyst for the nonenzymatic colorimetric detection of H2O2. In this study, we have developed a simple, low cost,...

Interfacial engineering regulating the peroxidase-like property of ternary composite nanofibers and their sensing applications

Interfacial engineering is an efficient and versatile strategy to accelerate the catalytic performance of functional nanomaterials. Herein, we have constructed ternary titanium dioxide (TiO2)@molybdenum disulfide (MoS2)/cobalt ferrite (CoFe2O4) composite nanofibers via a two-step hydrothermal reaction. Firstly, MoS2 nanosheets are grown on TiO2 nanofibers, then acting as an interfacial barrier to load ultrafine CoFe2O4 nanoparticles. Thanks to the synergistic effects among the interfacial interactions between MoS2 and TiO2 as well as CoFe2O4 component, the prepared ternary TiO2@MoS2/CoFe2O4 composite nanofibers displayed much better catalytic activity than any single and bicomponent composite nanofibers for peroxidase mimicking. Due to the superior catalytic efficiency of the ternary TiO2@MoS2/CoFe2O4 composite nanofibers, a highly sensitive way for l-cysteine sensing was developed. Our work offers an advanced surface engineering solution to construct a peroxidase-like catalyst to detect l-cysteine, with bright future in environmental science and biological technology.

Hierarchically structured Fe3O4-doped MnO2 microspheres as an enhanced peroxidase-like catalyst for low limit of detection

Abstract In order to lower the limit of detection of glucose, a peroxidase-like artificial enzyme with elevated catalysis capacity has been achieved. Fe3O4-doped MnO2 microspheres were fabricated through a two-step hydrothermal method for this purpose. TEM revealed that down-sized Fe3O4 nanoparticles were dispersed throughout the urchin-like MnO2 burrs. An additional XRD peak beyond Fe3O4 and MnO2 nanoparticles was observed, indicating a dislocation structure was formed. The defect in structure as well as the synergistic effect would allow extra enzyme ability. Based on the steady-state kinetic analyses and Michaelis–Menten model, the Michaelis–Menten constants (Km and vmax) were figured out. The results showed that the Fe3O4–MnO2 composite has elevated affinity toward the substrate TMB and H2O2. The limit of detection for glucose was estimated to be 0.75 μmol L−1 based on the Fe3O4–MnO2 composite artificial enzyme. The superparamagnetic properties endowed the material easy separation. The composite of this structure will provide a highly sensitive candidate method for accurate detection of glucose.

Glycothermal synthesis of fluorinated Fe3O4 microspheres with distinct peroxidase-like activity

The intrinsic peroxidase-like activity of magnetite (Fe3O4) has to be improved to activate H2O2 under mild conditions for practical applications. Herein fluorinated Fe3O4 microspheres (F-Fe3O4-r, r: 0.1–3), where r indicates the F/Fe molar ratio in the reaction mixture, were prepared by glycothermal synthesis and characterized by various complementary techniques. Fluoride ions were enriched on the surface of F-Fe3O4-1, and may substitute lattice oxygen or ion-exchange with surface hydroxyl groups. Kinetic study showed that the apparent activation energy for catalytic decomposition of H2O2 over F-Fe3O4-1 was significantly lower than those over unmodified Fe3O4 or other heterogeneous peroxidase-like catalysts (20.3 vs. 32.8–142 kJ mol−1), which improved the low-temperature activity of the former (decomposition rate of H2O2 at 25 °C: 0.0150 h−1). Potential applications of F-Fe3O4-1 in wastewater treatment were demonstrated by catalytic degradation of orange G with H2O2 at pH 6.8 and 25 °C.

Nanoceria-based reactive species scavenging activity of antioxidants using N,N-dimethyl-p-phenylenediamine (DMPD) probe

The aim of this work was to develop a fast and low-cost method to measure the reactive species formed in an aqueous suspension utilizing nanoceria as a peroxidase-like catalyst.

Micelle-embedded coating with ebselen for nitric oxide generation.

Nitric oxide generation is considered to be a key factor to mimic endothelial function in terms of anti-coagulation and anti-hyperplasia. Herein, ebselen which could play the similar role as glutathion peroxidase-like was loaded into micelles and was further assembled into a layer-by-layer coating. The ability of nitric oxide generation and corresponding biological effect were investigated. Endothelial-mimetic surface has now attracted huge attention in blood-contacting materials, due to its inherent ability of secreting nitric oxide. Among those categories, nitric oxide generation surface is considered to be safe and tunable in the modification of vascular biomedical devices. How to adsorb or immobilize glutathion peroxidase-like catalyst and maintain sustained/safe nitric oxide generation is full of interest. This study aimed at developing a functional coating constructed via layer-by-layer assembly to introduce the catalyst into the coating by pre-loading ebselen in micelles. We firstly introduced phenylboronic acid moiety into the micelle molecule backbone and grafted catechol moiety to chitosan backbone. Then, chitosan, micelles (containing ebselen) and heparin were adopted as polyelectrolytes and then alternatively assembled onto the substrate via layer-by-layer protocol. The catechol was conjugated to the amine groups of chitosan by Schiff base reaction to synthesize chitosan-catechol. The hydrophobic cholesterol was conjugated to the one end of the hydrophilic hyaluronic acid, and the hydroxymethylphenylboronic acid was conjugated to the other end via the esterification of carboxyl (–COOH) and hydroxyl (–OH). The modified hyaluronic acid could spontaneously form micelles in aqueous solution. Ebselen was the loaded into the as-prepared micelles. Chitosan-catechol, heparin, and micelles were alternatively assembled onto the substrate layer by layer to form a micelle-embedded coating. The micelle-embedded coating with ebselen was successfully obtained and the nitric oxide generation ability was in a safe level which was close to healthy endothelial cells. The coating could effectively inhibit platelet adhesion and smooth muscle cell proliferation. The use of ebselen preloaded into micelles could provide a sustained release of catalyst for in situ nitric oxide generation. Besides, this method could also be used to load diverse drugs and regulate desired properties. The study was approved by the Institutional Review Board of the West China Hospital in Sichuan University on March 3, 2018, with approval No. K2018044.

Plasmonic Cu/CuCl/Cu2S/Ag and Cu/CuCl/Cu2S/Au Supports with Peroxidase-Like Activity: Insights from Surface Enhanced Raman Spectroscopy

Abstract In the present study, we present nanostructured bimetallic Cu/CuCl/Cu2S/Au(Ag) supports that exhibit plasmonic electromagnetic field enhancement and peroxidase-like catalytic activity. The Cu2S component acts as the peroxidase-like catalyst, while the Au or Ag component provides the necessary light enhancement for surface enhanced Raman spectroscopic (SERS) studies of surface bound molecular reactants. As a test reaction the catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in presence of H2O2 was investigated. The comparison of product evolution in solution measured by UV-Vis spectroscopy and on the surface measured via SERS is able to give more insight into the different steps involved in the overall catalysis.

Highly efficient Fenton and enzyme-mimetic activities of NH2-MIL-88B(Fe) metal organic framework for methylene blue degradation

Here, we show that NH2-MIL-88B(Fe) can be used as a peroxidase-like catalyst for Fenton-like degradation of methylene blue (MB) in water. The iron-based NH2-MIL-88B(Fe) metal organic framework (MOF) was synthesized by a facile and rapid microwave heating method. It was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction, and the Brunauer–Emmett–Teller method. The NH2-MIL-88B(Fe) MOF possesses intrinsic oxidase-like and peroxidase-like activities. The reaction parameters that affect MB degradation were investigated, including the solution pH, NH2-MIL-88B(Fe) MOF and H2O2 concentrations, and temperature. The results show that the NH2-MIL-88B(Fe) MOF exhibits a wide working pH range (pH 3.0–11.0), temperature tolerance, and good recyclability for MB removal. Under the optimal conditions, complete removal of MB was achieved within 45 min. In addition, removal of MB was above 80% after five cycles, showing the good recyclability of NH2-MIL-88B(Fe). The NH2-MIL-88B(Fe) MOF has the features of easy preparation, high efficiency, and good recyclability for MB removal in a wide pH range. Electron spin resonance and fluorescence probe results suggest the involvement of hydroxyl radicals in MB degradation. These findings provide new insight into the application of high-efficient MOF-based Fenton-like catalysts for water purification.

Colorimetric and chemiluminescent dual-readout immunochromatographic assay for detection of pesticide residues utilizing g-C3N4/BiFeO3 nanocomposites

Graphitic carbon nitride/bismuth ferrite nanocomposites (g-C3N4/BiFeO3 NCs) were synthesized by a facile one step sol-gel combustion method and employed as a peroxidase-like catalyst. Based on the catalytical activity on the luminol-H2O2 reaction, the nanocomposites were utilized as a colorimetric/chemiluminescent dual-readout immunochromatographic assay (ICA) for the multiplexed detection of pesticide residues by utilizing chlorpyrifos and carbaryl as the model analytes. In the proposed protocol, chlorpyrifos antibody and carbaryl antibody were tagged to g-C3N4/BiFeO3 NCs for developing the spatially-resolved multianalyte ICA. After two competitive immunoreactions completed on the ICA test strip, the tracer antibodies were captured by the immobilized antigens on two test lines. The accumulation of g-C3N4/BiFeO3 NCs led to the appearance of brown color, which were observed as a colorimetric and semi-quantitative signal. Furthermore, the g-C3N4/BiFeO3 NCs-driven generation of CL signal was collected as a sensitively quantitative signal after initiating the luminol-H2O2 reaction on the test lines. Under the optimal conditions, the limits of detection of chlorpyrifos and carbaryl were both 0.033ng/mL. The dual-readout ICA was successfully used to detect chlorpyrifos and carbaryl spiked in environmental water and traditional Chinese medicine samples with acceptable recovery values of 80–119% and 90–118%. Due to many advantages including low cost, time efficiency, high sensitivity and good portability, the novel ICA showed great potential in many areas such as drug safety, environmental monitoring and clinical diagnosis.

Au-Ag and Pt-Ag bimetallic nanoparticles@halloysite nanotubes: morphological modulation, improvement of thermal stability and catalytic performance.

In this study, Au–Ag and Pt–Ag bimetallic nanocages were loaded on natural halloysite nanotubes (HNTs) via galvanic exchange based on Ag@HNT. By changing the ratio of Au to Ag or Pt to Ag in exchange processes, Au–Ag@HNT and Pt–Ag@HNT with different nanostructures were generated. Both Au–Ag@HNT and Pt–Ag@HNT systems showed significantly improved efficiency as peroxidase-like catalysts in the oxidation of o-phenylenediamine compared with monometallic Au@HNT and Pt@HNT, although inert Ag is dominant in the composition of both Au–Ag and Pt–Ag nanocages. On the other hand, loading on HNTs enhanced the thermal stability for every system, whether monometallic Ag nanoparticles, bimetallic Au–Ag or Pt–Ag nanocages. Ag@HNT sustained thermal treatment at 400 °C in nitrogen with improved catalytic performance, while Au–Ag@HNT and Pt–Ag@HNT maintained or even had slightly enhanced catalytic efficiency after thermal treatment at 200 °C in nitrogen. This study demonstrated that natural halloysite nanotubes are a good support for various metallic nanoparticles, improving their catalytic efficiency and thermal stability.

Ni-introduced CuAu nanocages: facile co-reduction synthesis of a novel magnetic multi-metallic nanostructure with high peroxidase mimetic activity

We design a simple route for the synthesis of novel octahedral Ni-introduced CuAu nanocages via a mild co-reduction process. Experiments showed that the as-prepared magnetic multi-metallic nanocages could be used as an efficient recyclable peroxidase-like catalyst.

A novel, enzyme-linked immunosorbent assay based on the catalysis of AuNCs@BSA-induced signal amplification for the detection of dibutyl phthalate

A novel, competitive, enzyme-linked immunosorbent assay (ELISA) was presented in this paper based on the inhibition of catalysis of AuNCs@BSA triggered by dissolved Ag+ for the detection of dibutyl phthalate (DBP). In the immunoassay system, numerous Ag+ was released from AgNPs (labelled on the second antibody, AgNPs@Ab2) in the presence of H2O2 after the competition step, preventing AuNCs@BSA from inducing a color change of 3,3′,5,5′-tetramethylbenzidine (TMB) to blue. Due to the signal amplification by the principle, the sensitivity of the modified ELISA was improved with the low limit of detection (LOD) of 4.017μg/L for DBP, which was decreased 16 times relative to that using conventional ELISA with the same antibody. In addition, the established method showed satisfactory accuracy and reliability (recoveries, 85.75–117.73%; CV, 1.33–6.79%) in spike-recovery analysis. To the best of our knowledge, this is the first time that AuNCs@BSA has been used in ELISA as a peroxidase-like catalyst. Our method shows great potential for trace DBP detection from environmental and food samples.

Fabrication of cobalt ferrite/cobalt sulfide hybrid nanotubes with enhanced peroxidase-like activity for colorimetric detection of dopamine

The development of highly sensitive and low-cost biosensors for the detection of dopamine is of paramount importance for medical diagnostics. Herein, we report the preparation of a new peroxidase-like catalyst with a uniform heterostructure by using a technique involving electrospinning, annealing and solvothermal reaction. In this catalyst system, cobalt sulfide (CoS) nanoparticles were homogenously distributed and supported on the surface of cobalt ferrite (CoFe2O4) nanotubes. The as-prepared CoFe2O4/CoS hybrid nanotubes showed remarkably high catalytic efficiency as peroxidase mimics toward the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) in the presence of H2O2. Owing to the synergistic effect between the CoFe2O4 and CoS component, the prepared CoFe2O4/CoS hybrid nanotubes exhibited enhanced peroxidase-like activity, exceeding that of either the CoS nanoparticles or CoFe2O4 nanotubes alone. Dopamine has been widely investigated due to its unique function in the nervous system. Consequently, various approaches have been developed for the sensitive determination of dopamine. In this work, a simple and sensitive colorimetric route for the detection of dopamine was established based on the ability of dopamine to induce the reduction of oxidized TMB to TMB with consequent fading of the blue color. This method shows a wide linear range (0–50μM) and a low detection limit of 0.58μM. The unique heterostructure with spinel/sulfide interfaces represents a new concept for the construction of highly efficient and multifunctional biocatalysts.

Strongly coupled CeO2/Co3O4/poly(3,4-ethylenedioxythiophene) nanofibers with enhanced nanozyme activity for highly sensitive colorimetric detection

In this work, we have prepared CeO2/Co3O4 composite nanofibers via an electrospinning technique followed by a calcination process. Then core–shell structured CeO2/Co3O4/poly(3,4-ethylenedioxythiophene) (PEDOT) composite nanofibers were fabricated through a redox reaction between the 3,4-ethylenedioxythiophene (EDOT) monomer and Co3O4 on the surface of CeO2/Co3O4 composite nanofibers. The morphology and composition of the two composite nanofibers were confirmed by field-emission scanning electron microscopy, transmission electron microscopy, x-ray diffraction, Fourier transform infrared spectroscopy, and x-ray photoelectron spectra measurements. Due to the synergistic effect between CeO2 and Co3O4, the catalytic activity was enhanced compared to that of independent oxide nanofibers. After the growth of PEDOT, the catalytic activity process was further improved, having achieved a secondary synergistic effect. Application of the two prepared composite nanofibers as peroxidase-like catalysts for the colorimetric detection of H2O2 was investigated. It is anticipated that this work can inspire researchers to develop various novel functional nanocomposites for applications in biosensing and environmental monitoring.

Novel Nanoparticle-based Colorimetric Probes and Sensors for Determining Phenolic Antioxidants, Biothiols, Nitrite and Hydrogen Peroxide

This study examines the principles and milestones of nanoparticle (NP)-based colorimetric sensors and probes developed by our research group. A novel method for antioxidant capacity estimation was developed on the polyphenol-mediated growth of Ag-NPs and optical monitoring of the corresponding plasmon absorption bands. A new optical sensor using Ellman's reagent-adsorbed gold nanoparticles in colloidal solution was devised to selectively determine biothiols. Nitrite was determined by means of 4-aminothiophenol-modified Au-NPs and naphthylethylene diamine as coupling agent. Hydrogen peroxide was detected with the use of Fe3O4 magnetite NPs as peroxidase-like catalyst using a N,N-dimethyl-p-phenylenediamine (DMPD) probe.