scholarly journals Atomically Dispersed Cu Nanozyme with Intensive Ascorbate Peroxidase Mimic Activity Capable of Alleviating ROS‐Mediated Oxidation Damage

2021 ◽  
pp. 2103977
Author(s):  
Yuan Chen ◽  
Hang Zou ◽  
Bo Yan ◽  
Xiaoju Wu ◽  
Weiwei Cao ◽  
...  
2004 ◽  
Vol 36 (2) ◽  
pp. 87-92 ◽  
Author(s):  
De-Jia Li ◽  
Hua Luo ◽  
Li-Ling Wang ◽  
Guo-Lin Zou

Abstract Superoxide anion and NO can react to form the highly oxidizing species peroxynitrite (ONOO−) which can react directly with hemoglobin (Hb) even in the presence of physiological concentration CO2. This research was to determine the ONOO−-mediated oxidation damage to the heme of oxyhemoglobin (oxyHb) under conditions expected in blood. Results showed that 8–10 mol ONOO− was needed to quickly and completely convert 1 mol oxyHb to methemoglobin (metHb). ONOO− (20–140 μM) caused rapid and extensive formation of metHb from oxyHb (50 μM) mainly occurring within first 5–20 min of incubation. The conversion efficiency reached 16%, 48%, 60%, 79% and 88% output of metHb after 90 min of incubation at 0, 20, 40, 100, and 140 μM ONOO− respectively. 1 mM CO2 caused a small decrease in the ability of ONOO− to oxidize oxyHb, and ONOO−-promoted conversion of oxyHb to metHb increased when pH decreased from 8.0 to 6.0. Relatively lower temperature in blood condition will inhibit this reaction in some degree. We postulate that ONOO− can mediate oxidation damage to the heme, and cause heme loss from the hydrophobic cavity of Hb when its concentration exceeded 90 μM. These results indicated that ONOO− could convert oxyHb to metHb under the conditions expected in blood, and this reaction was regulated by CO2 concentration, reaction time, temperature and pH value.


2020 ◽  
Vol 16 (5) ◽  
pp. 816-828
Author(s):  
Gurdeep Rattu ◽  
Nishtha Khansili ◽  
Prayaga M. Krishna

Background: Cerium oxide nanoparticles (nanoceria) are efficient free-radical scavengers due to their dual valence state and thus exhibit optical and catalytic properties. Therefore, the main purpose of this work was to understand the peroxidase mimic activity of polymer-stabilized nanoceria for enzyme-less H2O2 sensing by fluorescence spectrometer. Objective: This research revealed the development of fluorescence hydrogen peroxide nanosensor based on the peroxidase-like activity of polyacrylic acid stabilized nanoceria (PAA-CeO2 Nps). Methods: PAA-CeO2 Nps were synthesized by simple cross-linking reaction at a low temperature and characterized by XRD, SEM, Zeta potential, TGA, FT-IR and UV-VIS spectroscopic analysis. H2O2 sensing was performed by a fluorescence spectrometer. Results:: The synthesized polymer nanocomposite was characterized by XRD, SEM, TGA, FT-IR and UV-VIS spectroscopic analysis. The XRD diffraction patterns confirmed the polycrystalline nature and SEM micrograph showed nanoparticles having hexagonal symmetry and crystallite size of 32 nm. The broad peak of Ce–O bond appeared at 508 cm-1. UV-VIS measurements revealed a welldefined absorbance peak around 315 nm and an optical band-gap of 3.17 eV. As synthesized PAACeO2 Nps effectively catalysed the decomposition of hydrogen peroxide (H2O2) into hydroxyl radicals. Then terephthalic acid was oxidized by hydroxyl radical to form a highly fluorescent product. Under optimized conditions, the linear range for determination of hydrogen peroxide was 0.01 - 0.2 mM with a limit of detection (LOD) of 1.2 μM. Conclusion: The proposed method is ideally suited for the sensing of H2O2 at a low cost and this detection system enabled the sensing of analytes (sugars), which can enzymatically generate hydrogen peroxide.


2019 ◽  
Vol 821 ◽  
pp. 89-95
Author(s):  
Wanasorn Somphol ◽  
Thipjak Na Lampang ◽  
Paweena Prapainainar ◽  
Pongdhorn Sae-Oui ◽  
Surapich Loykulnant ◽  
...  

Poly (lactic acid) or PLA was reinforced by nanocellulose and polyethylene glycol (PEG), which were introduced into PLA matrix from 0 to 3 wt.% to enhance compatibility and strength of the PLA. The nanocellulose was prepared by TEMPO-mediated oxidation from microcrystalline cellulose (MCC) powder and characterized by TEM, AFM, and XRD to reveal rod-like shaped nanocellulose with nanosized dimensions, high aspect ratio and high crystallinity. Films of nanocellulose/PEG/PLA nanocomposites were prepared by solvent casting method to evaluate the mechanical performance. It was found that the addition of PEG in nanocellulose-containing PLA films resulted in an increase in tensile modulus with only 1 wt% of PEG, where higher PEG concentrations negatively impacted the tensile strength. Furthermore, the tensile strength and modulus of nanocellulose/PEG/PLA nanocomposites were higher than the PLA/PEG composites due to the existence of nanocellulose chains. Visual traces of crazing were detailed to describe the deformation mechanism.


Physchem ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 163-175
Author(s):  
Philipp Hawe ◽  
Vitor R. R. Silveira ◽  
Robert Bericat Vadell ◽  
Erik Lewin ◽  
Jacinto Sá

More sustainable solutions are needed to produce chemicals and fuels, mainly to face rising demands and mitigate climate change. Light, as a reagent, has emerged as a route to activate small molecules, e.g., H2O, CO2, N2, and make complex chemicals in a process called photocatalysis. Several photosystems have been proposed, with plasmonic technology emerging as one the most promising technologies due to its high optical absorption and hot-carrier formation. However, the lifetime of hot carriers is unsuitable for direct use; therefore, they are normally coupled with suitable charge-accepting materials, such as semiconductors. Herein, a system is reported consisting of Au supported in p-Cu2O. The combination of p-Cu2O intrinsic photoactivity with the plasmonic properties of Au extended the system’s optical absorption range, increasing photocatalytic efficiency. More importantly, the system enabled us to study the underlying processes responsible for hot-hole transfer to p-Cu2O. Based on photocatalytic studies, it was concluded that most of the holes involved in aniline photo-oxidation come from hot-carrier injections, not from the PIRET process.


2021 ◽  
Vol 6 ◽  
pp. 100102
Author(s):  
Mohd Bismillah Ansari ◽  
Ram Sambhar Shukla ◽  
Yong-Hwan Mo ◽  
Sang-Eon Park

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