Aldehyde catalysis – from simple aldehydes to artificial enzymes

: Biocatalysts or enzymes have a pivotal role in speeding up most of the biochemical reactions that drives life processes. Although substrate specific and promising, there are some pitfalls that limit their use for wide application. To counteract the shortcomings, artificial enzymes possessing enzyme characteristics with additional qualities have been devised and that kick-started in the late 2000s. This review aims to provide an overview of nanozymes, designing concept, nanomaterials and applications. To begin with, the limitations encountered by natural enzymes and its replacement with nanozymes have been highlighted. Secondly, how nanozymes evolved in due course of time, classification and engineering strategies have been briefly described. Most importantly, the engineering of nanozymes for improved catalytic activities have also been discussed. A clear distinction between the enzymatic-mimic for various clinical and bioimaging applications has been critically reviewed. With this rapidly emerging technology, there would be a great demand pertaining to scalability, biosafety, catalytic diversity and environmental challenge needs much consideration.

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Catalytically potent and selective clusterzymes for modulation of neuroinflammation through single-atom substitutions

Nature Communications ◽

10.1038/s41467-020-20275-0 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Haile Liu ◽

Yonghui Li ◽

Si Sun ◽

Qi Xin ◽

Shuhu Liu ◽

...

Keyword(s):

Catalytic Activity ◽

Catalytic Reactions ◽

Single Atom ◽

Artificial Enzymes ◽

Signal Molecules ◽

High Catalytic Activity ◽

Substrate Selectivity ◽

Catalytic Activities ◽

Injured Brain ◽

Enzyme Mimicking

AbstractEmerging artificial enzymes with reprogrammed and augmented catalytic activity and substrate selectivity have long been pursued with sustained efforts. The majority of current candidates have rather poor catalytic activity compared with natural molecules. To tackle this limitation, we design artificial enzymes based on a structurally well-defined Au25 cluster, namely clusterzymes, which are endowed with intrinsic high catalytic activity and selectivity driven by single-atom substitutions with modulated bond lengths. Au24Cu1 and Au24Cd1 clusterzymes exhibit 137 and 160 times higher antioxidant capacities than natural trolox, respectively. Meanwhile, the clusterzymes demonstrate preferential enzyme-mimicking catalytic activities, with Au25, Au24Cu1 and Au24Cd1 displaying compelling selectivity in glutathione peroxidase-like (GPx-like), catalase-like (CAT-like) and superoxide dismutase-like (SOD-like) activities, respectively. Au24Cu1 decreases peroxide in injured brain via catalytic reactions, while Au24Cd1 preferentially uses superoxide and nitrogenous signal molecules as substrates, and significantly decreases inflammation factors, indicative of an important role in mitigating neuroinflammation.

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Photocatalytic activity of TiO2 synthesized by anodization and anodic spark deposition

MRS Advances ◽

10.1557/adv.2020.405 ◽

2020 ◽

Vol 5 (61) ◽

pp. 3141-3152

Author(s):

Alma C. Chávez-Mejía ◽

Génesis Villegas-Suárez ◽

Paloma I. Zaragoza-Sánchez ◽

Rafael Magaña-López ◽

Julio C. Morales-Mejía ◽

...

Keyword(s):

Electron Microscopy ◽

Photocatalytic Activity ◽

Surface Characteristics ◽

Amorphous Solids ◽

X Ray Diffraction ◽

X Ray ◽

Catalytic Activities ◽

Anodic Spark Oxidation ◽

Porous Surfaces ◽

Scanning Electron

AbstractSeveral photocatalysts, based on titanium dioxide, were synthesized by spark anodization techniques and anodic spark oxidation. Photocatalytic activity was determined by methylene blue oxidation and the catalytic activities of the catalysts were evaluated after 70 hours of reaction. Scanning Electron Microscopy and X Ray Diffraction analysis were used to characterize the catalysts. The photocatalyst prepared with a solution of sulfuric acid and 100 V presented the best performance in terms of oxidation of the dye (62%). The electric potential during the synthesis (10 V, low potential; 100 V, high potential) affected the surface characteristics: under low potential, catalyst presented smooth and homogeneous surfaces with spots (high TiO2 concentration) of amorphous solids; under low potential, catalyst presented porous surfaces with crystalline solids homogeneously distributed.

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Fe-N-C Artificial Enzyme: Activation of Oxygen for Dehydrogenation and Monoxygenation of Organic Substrates under Mild Condition and Cancer Therapeutic Application

10.26434/chemrxiv.6427643.v1 ◽

2018 ◽

Author(s):

Fei He ◽

Li Mi ◽

Yanfei Shen ◽

Toshiyuki Mori ◽

Songqin Liu ◽

...

Keyword(s):

Mild Condition ◽

Enzyme Activation ◽

Artificial Enzymes ◽

Organic Substrates ◽

Artificial Enzyme ◽

Therapeutic Application ◽

Highly Efficient ◽

Activation Of Oxygen

Developing highly efficient artificial enzymes that directly employ O2 as terminal oxidant has long been pursued but has rarely achieved yet. We report Fe-N-C has unusual enzyme-like activity in both dehydrogenation and monoxygenation of organic substrates with ~100% selectivity by direct using O2.

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Metal-Assisted Plasma Etching of Silicon: A Liquid-Free Alternative to MACE

10.26434/chemrxiv.6128237 ◽

2018 ◽

Author(s):

Julia Sun ◽

Benjamin Almquist

Keyword(s):

Liquid Phase ◽

Plasma Etching ◽

Chemical Etching ◽

Gold Films ◽

Metallic Films ◽

Au Catalyst ◽

Feed Concentration ◽

Catalytic Activities ◽

Metal Assisted Chemical Etching ◽

Complex Nanostructures

For decades, fabrication of semiconductor devices has utilized well-established etching techniques to create complex nanostructures in silicon. Of these, two of the most common are reactive ion etching in the gaseous phase and metal-assisted chemical etching (MACE) in the liquid phase. Though these two methods are highly established and characterized, there is a surprising scarcity of reports exploring the ability of metallic films to catalytically enhance the etching of silicon in dry plasmas via a MACE-like mechanism. Here, we discuss a metal-assisted plasma etch (MAPE) performed using patterned gold films to catalyze the etching of silicon in an SF6/O2 mixed plasma, selectively increasing the rate of etching by over 1000%. The degree of enhancement as a function of Au catalyst configuration and relative oxygen feed concentration is characterized, along with the catalytic activities of other common MACE metals including Ag, Pt, and Cu. Finally, methods of controlling the etch process are briefly explored to demonstrate the potential for use as a liquid-free fabrication strategy.

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