PdIr Aerogels with Boosted Peroxidase-like Activity for a Sensitive Total Antioxidant Capacity Colorimetric Bioassay

  • Metallic aerogels (MAs), imparting the active catalytic properties of nanostructured noble metals to macroscopic aerogels, draw tremendous interest in diverse fields owing to the unique features of three-dimensional interconnected channels, self-supported architectures, and pure metallic backbones. Moreover, flexible manipulation of compositions, high electrical conductivity, and abundant active sites of MAs contribute to the great potential to mimic natural enzymes.
  • However, the cumbersome synthetic process takes a couple of hours to days, and unavoidable impurities usually impede surface electrons/mass transfer, posing the decrease of stability and enzyme-like activity of MAs. Here, a PdIr bimetallic aerogel prepared in the ethanol phase via spontaneous assembly and a surfactant-free strategy is reported. Gelation kinetics of PdIr aerogels in ethanol is increased with 2-4 orders of magnitude compared to the traditional preparation method in water.
  • Owing to the intrinsic physicochemical properties, PdIr aerogels exhibit the high activity of peroxidase mimics using 3,3′,5,5′-tetramethylbenzidine as a chromogenic probe. In addition, the PdIr aerogels maintain relatively high activity at an elevated temperature and pH of 3-7, demonstrating their good stability and survivability. Utilizing the exceptional peroxidase-like activity of PdIr aerogels, we realized the quantitative bioassay for H2O2 and total antioxidant capacity, indicating enormous potential in the quality evaluation of real samples.

A liquid colorimetric chemosensor for ultrasensitive detection of glyphosate residues in vegetables using a metal oxide with intrinsic peroxidase catalytic activity

The control of pesticide residues in food is of increasing importance nowadays due to the over-use and misapplication of herbicides in agricultural production. However, the current colorimetric method for rapid detection of glyphosate still faces many challenges like the low sensitivity and stability. Herein, a simple and ultrasensitive liquid colorimetric chemosensor for glyphosate detection was successfully constructed. Glyphosate pesticide can interact with metallic oxidelike porous Co3O4 nanodisc, and inhibit its inherent peroxidase-mimicking activity, making the colour of the solution change from blue to light blue or even colourless.
The colour variation of the colorimetric chemosensor enables us to easily distinguish in less than 20 min even by the naked eye whether glyphosate exceeds the allowable level. The limit of detection (LOD) of the chemosensor for glyphosate was calculated as low as 2.37 μg·L-1, and the chemosensor displays excellent selectivity against other competitive pesticides and metal ions. Further studies have also validated the applicability of the colorimetric chemosensor in actual samples like tomato, cucumber and cabbage, indicating that the proposed strategy may have promising application prospects for detecting glyphosate residues in agricultural products.

Colorimetric detection of alkaline phosphatase activity based on pyridoxal phosphate-induced chromatic switch of polydiacetylene nano-liposomes

A colorimetric assay based on polydiacetylenes (PDA) nano-liposomes is reported for facile and sensitive detection of alkaline phosphatase (ALP) activity. The critical basis of this method is that the interaction of pyridoxal phosphate (PLP) with nitrogenous group functionalized PDA nano-liposomes induces distinct blue-to-red color changes of PDA nano-liposomes. In the presence of ALP, as a nature substrate, PLP is enzymatically hydrolyzed to form pyridoxal, which cannot interact with PDA nano-liposomes.
As a result, the concentration of PLP is reduced and the color change of PDA nano-liposomes is retarded, which is associated with ALP level. Under optimal conditions, the proposed method showed good linear relationship with ALP activity in the range 10-200 U/L with a limit of detection of 2.8 U/L. The detection process could be vividly observed with the naked eye. Additional attempts by using the method for the evaluation of inhibitor efficiency were also achieved with satisfying results. The method was further challenged with real human serum samples, showing consistent results when compared with a commercial standard assay kit. Such simple and easy-to-use approach may provide a new alternative for clinical and biological detection of ALP.

Multienzyme mimetic activities of holey CuPd@H-C 3 N 4 for visual colorimetric and ultrasensitive fluorometric discriminative detection of glutathione and glucose in physiological fluids

Nanozymes with multiple activities have drawn immense interest owing to their great prospect in biochemical analysis. Fabricating nanomaterials-based artificial enzymes for multiple-enzyme mimetic activity is a significant challenge. This paper reports a sensitive biosensing platform to mimic the peroxidase, oxidase, and catalase-like activity by bimetallic CuPd embedded holey carbon nitride (CuPd@H-C3N4). Owing to the combination of porous H-C3N4 and bimetallic CuPd nanoparticles, the CuPd@H-C3N4 exhibited a large specific surface area, extremely high mobility and catalytic activity of electrons, resulting in remarkable triple-enzyme mimetic activity.
Owing to the excellent oxidase/peroxidase-like activities of CuPd@H-C3N4, a visual colorimetric and ultrasensitive fluorometric biosensing platform was established for the discriminatory detection of glutathione (linear range: 2-40 μM) and glucose (linear range: 0.1-40 μM) in physiological fluids, respectively. The fluorescence detection system showed ultrahigh sensitivity toward H2O2, with a linear range of 30-1500 nM. In addition, a one-step glucose detection strategy was proposed to replace the traditional, complicated two-step detection method, which simplifies the operation steps and improves the detection efficiency. The assay presented in this paper offers an effective multiple-enzymes mimicking detection platform that broaden its promising applications in biomedicine analysis and monitoring.

Peroxidase-like activity of Ru-N-C nanozymes in colorimetric assay of acetylcholinesterase activity

Herein, the Ru-N-C nanozymes with abundant active Ru-Nx sites have been successfully prepared by pyrolyzing Ru(acac)3 trapped zeolitic-imidazolate-frameworks (Ru(acac)3@ZIF-8). Taking advantages of the remarkable peroxidase-mimicking activity, outstanding stability and reusability of Ru-N-C nanozymes, a novel biosensing system with explicit mechanism is strategically fabricated for sensitively determining acetylcholinesterase (AChE) and tacrine. The limit of detection for AChE activity can achieve as low as 0.0433 mU mL-1, and the IC50 value of tacrine for AChE is about 0.190 μmol L-1.
The robust analytical performance in serums test verifies the great application potential of this assay in real matrix. Furthermore, “INH” and “IMPLICATION-AND” logic gates are rationally constructed based on the proposed colorimetric sensor. This work not only provides one sustainable and effective avenue to fabricate Ru-N-C-based peroxidase mimic with high catalytic performance, and also gives new impetuses for developing novel biosensors by applying Ru-N-C-based enzyme mimics as substitutes for the natural enzyme.

GST Colorimetric Activity Assay

KT-204 Kamiya Biomedical Company 100 tests 527 EUR

GST Colorimetric Activity Assay Kit

55R-1353 Fitzgerald 100 assays 540 EUR

GST Colorimetric Activity Assay Kit

GWB-AXR176 GenWay Biotech 100 assays Ask for price

GST Colorimetric Activity Assay Kit

K2108-100 ApexBio 100 assays 600 EUR

GST Colorimetric Activity Assay Kit

K263-100 Biovision each 588 EUR

HDAC Colorimetric Activity Assay Kit

GWB-AXR200 GenWay Biotech 100 assays Ask for price

HAT Activity Colorimetric Assay Kit

K2033-100 ApexBio 100 assays 498 EUR

HAT Activity Colorimetric Assay Kit

K332-100 Biovision each 646.8 EUR

HDAC Activity Colorimetric Assay Kit

K2032-100 ApexBio 100 assays 602.4 EUR

HDAC Activity Colorimetric Assay Kit

K2032-96 ApexBio 96 tests 389 EUR

HDAC Activity Colorimetric Assay Kit

K331-100 Biovision each 588 EUR

Lipase Activity Colorimetric Assay Kit

K2227-100 ApexBio 100 assays 470 EUR

Urease Activity Assay Kit (Colorimetric)

K378-100 Biovision each 601.2 EUR

ATPase Activity Assay Kit (Colorimetric)

K417-100 Biovision each 516 EUR

Lipase Activity Colorimetric Assay Kit

K722-100 Biovision each 614.4 EUR

Catalase Colorimetric Activity Kit (2 Plate)

K033-H1 Arbor Assays 2 x 96 well plate 425 EUR

Glyoxalase II Activity Kit (Colorimetric)

K460-100 Biovision each 666 EUR

Amylase Activity Colorimetric Assay Kit

K2225-100 ApexBio 100 assays 384 EUR

Trypsin Activity Colorimetric Assay Kit

K2176-100 ApexBio 100 assays 409 EUR

Trypsin Activity Colorimetric Assay Kit

K771-100 Biovision each 542.4 EUR

Plasmin Activity Assay Kit (Colorimetric)

K945-100 Biovision each 535.2 EUR

Amylase Activity Colorimetric Assay Kit

K711-100 Biovision each 489.6 EUR

Fumarase Activity Colorimetric Assay Kit

K596-100 Biovision each 783.6 EUR

Aldolase Activity Colorimetric Assay Kit

K665-100 Biovision each 796.8 EUR

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.

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