A Remarkably Efficient MnFe<sub>2</sub>O<sub>4</sub>‐based Oxidase Nanozyme

Vernekar, Amit A.; Das, Tandrila; Ghosh, Satadal; Mugesh, Govindasamy

doi:10.1002/asia.201500942

Cited by 117 publications

(58 citation statements)

References 30 publications

(24 reference statements)

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“…It is interesting to note that while many peroxidase nanozymes were reported (i.e., using H2O2 as a cosubstrate), very few have oxidase activity. 9,[19][20][21][22][23] The best known examples are gold nanoparticles for glucose oxidation, 9 and CeO2 nanoparticles (nanoceria) that oxidize a diverse range of substrates. 20 Oxidase nanozymes are important since they do not require unstable H2O2 as a co-substrate.…”

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confidence: 99%

Boosting the oxidase mimicking activity of nanoceria by fluoride capping: rivaling protein enzymes and ultrasensitive F⁻detection

2016

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Nanomaterial-based enzyme mimics (nanozymes) are currently a new forefront of chemical research. However, the application of nanozymes is limited by its low catalytic activity and low turnover numbers. Cerium dioxide nanoparticles (nanoceria) is among the few with oxidase activity. Herein, we report an interesting finding addressing its limitations. The oxidase activity of nanoceria is improved by over 100-fold by fluoride capping, rendering it more close to real oxidases (e.g., cytochrome P450). The turnover number reached 700 in 15 min, drastically improved from ~15 turnovers for the naked particles. The mechanism is attributed to surface charge modulation and facilitated electron transfer by Fcapping based on ζ-potential and free radical measurement. Ultrasensitive sensing of fluoride was achieved with a detection limit of 0.64 µM F -in water and in toothpastes, while no other tested anions can achieve the activity enhancement.Developing nanomaterial-based enzyme mimics, known as nanozymes, is a new frontier in inorganic, materials and analytical chemistry. [1][2][3][4][5][6][7] Nanozymes are a subset of nanoparticle-based catalysts that catalyze enzyme-like reactions at ambient conditions. Nanozymes are attractive not only for their high stability and lowcost, but also for studying fundamental processes at nanoscale surfaces. 2 Many nanoparticles such as gold, 4,8,9 graphene oxide, 10,11 and various metal oxides 1,3,5,12-19 possess oxidase, peroxidase, and/or catalase like activities. It is interesting to note that while many peroxidase nanozymes were reported (i.e., using H2O2 as a cosubstrate), very few have oxidase activity. 9,[19][20][21][22][23] The best known examples are gold nanoparticles for glucose oxidation, 9 and CeO2 nanoparticles (nanoceria) that oxidize a diverse range of substrates. 20 Oxidase nanozymes are important since they do not require unstable H2O2 as a co-substrate.Nanoceria is a versatile nanozyme, displaying oxidase, 16,20 catalase, 24,25 superoxide dismutase, 26,27 and phosphatase 28 activities under different conditions. In 2009, Asati and co-workers first reported the oxidase-like activity of nanoceria. 20 Since then, nanoceria has become an attractive system receiving extensive studies. The catalytic activities of nanoceria were attributed to the mixed oxidation states of Ce 3+ and Ce 4+ , and related oxygen vacancies. 29,30 The role of redox states, 24 surface coating, 20 pH, 31 buffer composition, 32 and nucleotide triphosphate 16 were investigated. We hypothesize that surface chemistry plays a critical role in modulating substrate/product adsorption and electron transfer, thus influencing catalytic efficiency. A challenge in the nanozyme field is poor catalytic activity and low turnover, which is in sharp contrast to their highly efficient protein counterparts.

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Boosting the oxidase mimicking activity of nanoceria by fluoride capping: rivaling protein enzymes and ultrasensitive F⁻detection

2016

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“…Finally, in case of O 1 s peaks, we observed unusual bond splitting into two peaks (529.8 and 532.8 eV) which denotes that the formation of ionic bonds between metals (Mn/Fe) with oxygen and hydroxyl group respectively. These results suggested that the Mn and Fe are in the oxidation state of +2 and +3 ions respectively [8,24,31,32].…”

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confidence: 88%

Manganese ferrite nanocubes as an MRI contrast agent

Ravichandran

Velumani

2020

Mater. Res. Express

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Facile synthesis of superparamagnetic, highly crystalline, manganese ferrite nanocubes (MnNCs) is reported. X-ray diffraction depicts single-phase face-centred cubic spinel and the electron microscopy represents the nearly monodispersed cube-like nanostructure with the size ranging from 18 to 20 nm. Vibrating sample magnetometer shows magnetization field-dependent curves at 300 K exhibiting the superparamagnetic behaviour of NCs with negligible remanence. Furthermore, the biocompatibility of NCs was proved by MTT assay. These unique characteristics make this NCs as a contrast agent ideally suited for T 2 -weighted MR imaging. This novel method of synthesizing NCs proves to be very attractive for various biomedical applications because of their outstanding stability and biocompatibility.

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“…20 Verneker et al developed an efficient synthesis of MnFe 2 O 4 via a co-precipitation method with controlled morphology; it showed remarkable oxidase mimetic properties. 21 Graphene quantum dot-Ag nanoparticles show high oxidase and antibacterial properties for Gram-negative, Gram-positive and drug-resistant bacteria. 22 Cerium oxide was also studied for pH-tuneable oxidase activity for cancer folate biomarker sensors.…”

Section: Introductionmentioning

confidence: 99%

Colorimetric sensing of chlorpyrifos through negative feedback inhibition of the catalytic activity of silver phosphate oxygenase nanozymes

2020

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A Remarkably Efficient MnFe₂O₄‐based Oxidase Nanozyme

Cited by 117 publications

References 30 publications

Boosting the oxidase mimicking activity of nanoceria by fluoride capping: rivaling protein enzymes and ultrasensitive F⁻detection

Boosting the oxidase mimicking activity of nanoceria by fluoride capping: rivaling protein enzymes and ultrasensitive F⁻detection

Manganese ferrite nanocubes as an MRI contrast agent

Colorimetric sensing of chlorpyrifos through negative feedback inhibition of the catalytic activity of silver phosphate oxygenase nanozymes

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A Remarkably Efficient MnFe2O4‐based Oxidase Nanozyme

Cited by 117 publications

References 30 publications

Boosting the oxidase mimicking activity of nanoceria by fluoride capping: rivaling protein enzymes and ultrasensitive F−detection

Boosting the oxidase mimicking activity of nanoceria by fluoride capping: rivaling protein enzymes and ultrasensitive F−detection

Manganese ferrite nanocubes as an MRI contrast agent

Colorimetric sensing of chlorpyrifos through negative feedback inhibition of the catalytic activity of silver phosphate oxygenase nanozymes

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A Remarkably Efficient MnFe₂O₄‐based Oxidase Nanozyme

Boosting the oxidase mimicking activity of nanoceria by fluoride capping: rivaling protein enzymes and ultrasensitive F⁻detection

Boosting the oxidase mimicking activity of nanoceria by fluoride capping: rivaling protein enzymes and ultrasensitive F⁻detection