Toxic phenol pollutants pose a great threat to the environment, it is urgent to develop an efficient and recyclable method to monitor phenol. Herein, we reported the synthesis of catalase-Fe3O4@ZIF-8 (CAT-Fe3O4@ZIF-8) through a novel amino-acid-boosted one-pot embedding strategy that synergically integrated catalase and magnetic Fe3O4 nanoparticles with ZIF-8. As expected, CAT-Fe3O4@ZIF-8 exhibited enhanced catalytic activity compared with Fe3O4@ZIF-8, CAT@ZIF-8 and catalase. Depending on the satisfactory performance of CAT-Fe3O4@ZIF-8, a colorimetric detection platform for phenol based on CAT-Fe3O4@ZIF-8 was constructed.
The corresponding detection limit was as low as 0.7 μM, and a wide linear range of 5-100 μM was obtained. Besides, CAT-Fe3O4@ZIF-8-based colorimetric detection platform has been verified to possess high stability and recyclability. The proposed method was proven to have potential practical applications in the field of water treatment, which would advance efficient, recyclable monitoring of water quality.
Salt-template preparation of Mo 5 N 6 nanosheets with peroxidase- and catalase-like activities and application for colorimetric determination of 4-aminophenol
Mo5N6 nanosheets were synthesized by a nickel-induced growth method and were found to possess peroxidase-like activity in acidic condition and catalase-like activity in weak basic condition. In acidic condition, Mo5N6 nanosheets can catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2 to form a blue color product (TMBOX). At the co-existence of 4-aminophenol (4-AP), 4-AP can react with H2O2 and TMBOX, resulting in the decrease of TMBOX and the fading of blue color. Therefore, a facile, sensitive colorimetric method for the quantitative detection of 4-AP was developed.
The linear range for 4-AP was 1.0 to 80.0 μmol⋅L‒1 (R2 = 0.999), and the detection limit was 0.56 μmol⋅L‒1 based on 3σ/k. Resorcinol, aniline, humic acid, and common ions and anions in surface water did not interfere the determination of 4-AP. This colorimetric method was applied to measure the 4-AP in real water sample from Wulong River in Fujian Province of China. The relative standard deviation for the determination of 4-AP was ranged from 0.03 to 1.88%, and the recoveries from spiked samples were ranged between 99.2 and 107.6%. The determination results were consistent with those obtained by HPLC.
Catalase-integrated metal-organic framework with synergetic catalytic activity for colorimetric sensing
As a platform for enzyme immobilization, metal-organic frameworks (MOFs) can protect enzyme activity from the interference of external adverse environment. Although these strategies have been proven to produce good results, little consideration has been given to the functional similarity of MOFs to the encapsulated enzyme. Here, catalase (CAT) was encapsulated in Fe-BTC with peroxidase-like activity to obtain a stable composite (CAT@Fe-BTC) with synergistic catalytic activity. Depending on the superior selectivity and high catalytic activity of CAT@Fe-BTC, colorimetric sensing for the detection of hydrogen peroxide and phenol was developed. This work demonstrates that the integration of functional MOFs with natural enzyme can be well applied to the construction of efficient catalysts.
Cadmium cobaltite nanosheets synthesized in basic deep eutectic solvents with oxidase-like, peroxidase-like, and catalase-like activities and application in the colorimetric assay of glucose.
Cadmium cobaltite (CdCo2O4) nanosheets were ultra-fast synthesized based on a new basic deep eutectic solvent (DES) which served simultaneously as 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 652 nm increases linearly in the 0.5 to 100 μM concentration range, and the limit of detection is 0.13 μM (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.
Co3O4 nanocrystals as an efficient catalase mimic for the colorimetric detection of glutathione.
Nanomaterial-based artificial enzymes (nanozymes), as an emerging generation of artificial enzymes, have received extensive attention in recent years owing to their striking merits. In this study, the obtained Co3O4 nanocrystals exhibited catalase-like activity and could catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2, and a clear absorption peak at 652 nm can be observed. It was verified that the catalytic activity for the oxidation of TMB originated from the oxygen, which is generated by Co3O4 catalyzed H2O2 decomposition.
Upon addition of glutathione (GSH), the catalytic ability of the Co3O4 nanocrystals was inhibited. And, the changes of absorbance at 652 nm could be utilized to quantify the concentration of GSH. Under the optimized conditions, the proposed assay showed good linear relationships and a low detection limit towards GSH. Moreover, the Co3O4 nanocrystals had excellent stability and can maintain the catalytic activity for a long time. Thus, a simple, sensitive and selective nanozyme-based biosensor was developed for the colorimetric detection of GSH.
Catalase (CAT) Colorimetric Assay Kit |
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| MBS2556989-48Test | 48Test | 230 EUR |
Catalase (CAT) Colorimetric Assay Kit |
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| MBS2556989-48Tests | 48Tests | 230 EUR |
Catalase (CAT) Colorimetric Assay Kit |
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| MBS2556989-5x96Tests | 5x96Tests | 1145 EUR |
Catalase (CAT) Colorimetric Assay Kit |
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| MBS2556989-96Test | 96Test | 250 EUR |
Catalase (CAT) Colorimetric Assay Kit |
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| MBS2556989-96Tests | 96Tests | 250 EUR |
Catalase Colorimetric Activity Kit (2 Plate) |
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| K033-H1 | 2 x 96 well plate | 425 EUR |
OKAU00112-2PLATE - Catalase Colorimetric Activity Kit |
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| OKAU00112-2PLATE | 2plate | 379 EUR |
Catalase Activity Colorimetric/Fluorometric Assay Kit |
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| K2177-100 | 100 assays | 427 EUR |
Catalase Activity Colorimetric/Fluorometric Assay Kit |
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| K773-100 | each | 502.8 EUR |
OxiSelect™ Catalase Activity Assay Kit (Colorimetric) |
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| STA-341 | 96 assays | 595 EUR |
OxiSelect Catalase Activity Assay Kit (Colorimetric), Trial Size |
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| STA-341-T | 20 assays | 435.6 EUR |
Cathepsin G Substrate, Colorimetric |
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| 2206-25 | each | 360 EUR |
Cathepsin G Substrate, Colorimetric |
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| 2206-5 | each | 138 EUR |
Urea Colorimetric Assay |
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| TBS2201 | 500 tests | 259 EUR |
Boron Colorimetric Assay |
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| TBS2301-200 | 200 tests | 360 EUR |
Colorimetric Substrate, 5ML |
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| C129-5ML | 5ML | 254 EUR |
HRP Colorimetric Substrate |
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| 79651 | 10 ml | 105 EUR |
HDAC Substrate, Colorimetric |
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| 2207-100 | each | 360 EUR |
HDAC Substrate, Colorimetric |
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| 2207-25 | each | 151.2 EUR |
Tyrosine Colorimetric Assay |
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| TBS2070-100 | 100 tests | 429 EUR |
Colorimetric DTT Assay kit |
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| DTT100C | 100 assays | 221.78 EUR |
AMP Colorimetric Assay Kit |
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| K229-100 | each | 692.4 EUR |
Colorimetric determination of the activities of tyrosinase and catalase via substrate-triggered decomposition of MnO2 nanosheets.
The authors describe novel colorimetric assays for tyrosinase (TYR) and catalase (CAT) based on the substrate-triggered decomposition of MnO2 nanosheets (NSs). The MnO2 NSs can act as oxidase mimics that catalyze the oxidation of the substrate tetramethylbenzidine (TMB) to form a blue dye with an absorption maximum at 652 nm. The oxidase-mimicking activity of the MnO2 NSs is inhibited by dopamine (DA)/hydrogen peroxide (H2O2) due to their decomposition of the MnO2 NSs. TYR catalyzes the oxidation of DA while CAT can decompose H2O2 into water and oxygen.
Therefore, the oxidase-mimicking activity of MnO2 NSs is restored in the presence of both enzymes and their substrates. Based on the competitive consumption of substrates between enzymes and MnO2 NSs, a colorimetric method for determination of enzyme activity and its substrate is developed. The detection limits for TYR and CAT are 6 mU·mL-1 and 33 mU·mL-1, respectively. Graphical abstractA colorimetric method for monitoring enzyme activity and its substrate is described. It is based on the substrate-inhibited oxidase-mimicking activity of MnO2 nanosheets.