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Bacterial infection has become a global health issue.The misuseantibiotics has been resulting in increased drug resistance and bioaccumulation.Therefore,developing a highly safe antibacterial agent,with high antibacterial performa...
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Bacterial infection has become a global health issue.The misuseantibiotics has been resulting in increased drug resistance and bioaccumulation.Therefore,developing a highly safe antibacterial agent,with high antibacterial performance is demanding.Inspired by the natural motors performing automated tasks in complicated living environments,we demonstrate tadpole-like nanoparticles(TNPs)with several functions,including high photothermal conversion efficiency,peroxidase-like catalytic activity,glutathione peroxidase-like activity,and catalase-like activity.TNPs produce hydroxyl radical(>>OH)at an extremely low concentrationhydrogen peroxide0.006%,which can damage bacterial cell membranes,proteins,and DNA.Moreover,the glutathione peroxidase-like activity disrupts the anti-oxidative mechanismbacteria and improves the permeabilitythe cell membranes,consequently enhancing the killing effectROS.In addition,TNPs possess tadpole-like asymmetry to overcome Brownian motion,demonstrating strong directional motion propelled by 02.The in vivo experiments indicate that TNPs could also shorten the inflammatory period and promote angiogenesis,making them a very promising antibacterial agent.
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Nanozymes based on rare earth oxides such as ceria have been promising as new non-antibiotic bactericidal tools. The activities of praseodymia mimicking both oxidase and peroxidase were examined which led to excellent oxidative ca...
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Nanozymes based on rare earth oxides such as ceria have been promising as new non-antibiotic bactericidal tools. The activities of praseodymia mimicking both oxidase and peroxidase were examined which led to excellent oxidative capacity in generating species such as holes and hydroxyl radicals. The antibacterial performance of praseodymia nanorods from precipitation method was investigated in comparison with commercial samples. Incubation of praseodymia with E. Coli results in significant reduction of bacterial proliferation in both swarming and inhibition experiments, but not with S. aureus. This could potentially provide a new bactericidal strategy to combat abiotic or strain-selective drug resistance in future applications.
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OBJECTIVES: This study was to test the peroxidase activity of the monodispers_x0002_porous silica microspheres.The use of synthesized microspheres as a support material reveals a linear increase in peroxidase activity with increas...
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OBJECTIVES: This study was to test the peroxidase activity of the monodispers_x0002_porous silica microspheres.The use of synthesized microspheres as a support material reveals a linear increase in peroxidase activity with increased concentration of genomic DNA.The results facilitate the development of a new diagnostic kit.MATERIALS and METHODS: The monodisperse-porous silica microspheres were 5 mm in size and with a coefficient of variation for size distribution less than 5%.The morphological investigation performed by SEM showed that the surface of microspheres was porous.The devleoped synthetic protocol of the magnetic silica microspheres allowed strong immobilization of magnetic Fe3O4 nanoparticles on the surface of the pore found within the microspheres.The presence of tightly immobilized Fe3O4 nanoparticles having an ability to interact with the enviroment should be probably the main reason of peroxidase-like activity of magnetic silica microspheres.RESULTS: In order to test the peroxidase-like activity of magnetic silica microspheres, tetramethylbenzidine (TMB) was used as the substrate.The effect of concentration of magnetic silica microspheres on the peroxidaselike activity was investigated in TE buffer medium using TMB as the synthetic substrate and a linear increase in the peroxidase-like activity with the increasing microsphere concentration.Besides, the effect of human genomic DNA concentration on the peroxidase-like activity of magnetic silica microspheres was investigated.The results showed that a linear increase occurred in the activity with the increasing DNA concentration.CONCLUSIONS: The results of presented study also allow the development of new diagnostic methods worked based on peroxidase-activity.The magnetic silica microspheres have a significant potential as support material for various biological molecules.Hence, the use of magnetic silica microspheres with this property instead of an expensive enzyme-peroxidase may provide serious advantages in the studies on the development of diagnostic test kits.
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Ascorbate peroxidases (APXs) are heme peroxidases involved in the control of hydrogen peroxide levels and signal transduction pathways related to development and stress responses. Here, a total of 238 APX , 30 APX-related ( APX-R ...
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Ascorbate peroxidases (APXs) are heme peroxidases involved in the control of hydrogen peroxide levels and signal transduction pathways related to development and stress responses. Here, a total of 238 APX , 30 APX-related ( APX-R ), and 34 APX-like ( APX-L ) genes were identified from 24 species from the Poaceae family. Phylogenetic analysis of APX indicated five distinct clades, equivalent to cytosolic ( cAPX ), peroxisomal ( pAPX ), mitochondrial ( mitAPX ), stromal ( sAPX ), and thylakoidal ( tAPX ) isoforms. Duplication events contributed to the expansion of this family and the divergence times. Different from other APX isoforms, the emergence of Poaceae mitAPXs occurred independently after eudicot and monocot divergence. Our results showed that the constitutive silencing of mitAPX genes is not viable in rice plants, suggesting that these isoforms are essential for rice regeneration or development. We also obtained rice plants silenced individually to sAPX isoforms, demonstrating that, different to plants double silenced to both sAPX and tAPX or single silenced to tAPX previously obtained, these plants do not show changes in the total APX activity and hydrogen peroxide content in the shoot. Among rice plants silenced to different isoforms, plants silenced to cAPX showed a higher decrease in total APX activity and an increase in hydrogen peroxide levels. These results suggest that the cAPXs are the main isoforms responsible for regulating hydrogen peroxide levels in the cell, whereas in the chloroplast, this role is provided mainly by the tAPX isoform. In addition to broadening our understanding of the core components of the antioxidant defense in Poaceae species, the present study also provides a platform for their functional characterization.
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Pathogenic bacteria infections have posed a threat to human health worldwide. Nanomaterials with natural enzymatic activity provide an opportunity for the development of new antibacterial pathways. We successfully constructed iron...
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Pathogenic bacteria infections have posed a threat to human health worldwide. Nanomaterials with natural enzymatic activity provide an opportunity for the development of new antibacterial pathways. We successfully constructed iron phosphate nanozyme-hydrogel (FePO4-HG) with the traits of positive charge and macropores. Interestingly, FePO4-HG displayed not only peroxidase-like activity under acidic bacterial infectious microenvironment but also superoxide dismutase-catalase-like synergistic effects in neutral or weak alkaline conditions, thus protecting normal tissues from the peroxidase-like protocol with exogenous H2O2 damage. Furthermore, the positive charge and macropore structure of FePO4-HG could capture and restrict bacteria in the range of ROS destruction. Obviously, FePO4-HG exhibited excellent antibacterial ability against MRSA and AREC with the assistance of H2O2. Significantly, the FePO4-HG + H2O2 system could efficiently disrupt the bacterial biofilm formation and facilitate the glutathione oxidation process to rapid bacterial death with low cytotoxicity. Moreover, FePO4-HG was unsusceptible to bacterial resistance development in MRSA. Animal experiments showed that the FePO4-HG + H2O2 group could efficiently eliminate the MRSA infection and present excellent wound healing without inflammation and tissue adhesions. With further development and optimization, FePO4-HG has great potential as a new class of antibacterial agents to fight antibiotic-resistant pathogens.
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In this work, we suggest a chitosan-modified popcorn-like Au-Ag nanoparticles (CSPNPs) based assay for high sensitive detection of melamine, in which CSPNPs not only provide with an intrinsic peroxidase-like activity but also act ...
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In this work, we suggest a chitosan-modified popcorn-like Au-Ag nanoparticles (CSPNPs) based assay for high sensitive detection of melamine, in which CSPNPs not only provide with an intrinsic peroxidase-like activity but also act as surface enhanced Raman scattering (SERS) substrates. CSPNPs can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine gm by H2O2 to the charge transfer complex (CTC), which contributes to a tremendous surface-enhanced resonant Raman scattering (SERRS) signals with 632.8 nm laser excitation. The target molecule melamine can generate an additional compound with H2O2, which means the available amount of H2O2 for the oxidation of TMB reduced. Correspondingly, the SERRS intensity of CTC is decreased. The decreased Raman intensity is proportional to the concentration of melamine over a wide range from 10 nM to 50 mu M (R-2=0.989), with a limit of detection CLOD) of 8.51 nM. Moreover, the proposed highly selective method is fully capable of rapid, separation-free detection of melamine in milk powder. (C) 2015 Elsevier B.V. All rights reserved.
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The peroxidase-like activity of ficin is relatively low, which limits its application. It was found that thiol groups of ficin could inhibit its peroxidase-like activity. So, two procedures, i.e., direct blocking with N-ethylmalei...
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The peroxidase-like activity of ficin is relatively low, which limits its application. It was found that thiol groups of ficin could inhibit its peroxidase-like activity. So, two procedures, i.e., direct blocking with N-ethylmaleimide (NEM), or using tris (2-carboxyethyl) phosphine hydrochloride (TCEP) to interrupt disulfide bonds then blocking thiol groups with NEM, were applied to block thiol groups of ficin, ficin-NEM (ficin-N) and ficin-TCEP-NEM (ficin-TN) were produced, respectively. The blocking of thiol groups accelerated the peroxidase activity dramatically. The peroxidase catalytic activity of ficin-N and ficin-TN toward the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) oxidation by H2O2 was about 2.5-fold and 5-fold increase compared with ficin, respectively, which accompanied a color change from colorless to blue and followed classic Michaelis-Menten model. The kinetic parameters indicated that higher affinity of ficin-N (K-m = 0.31) and ficin-TN (K-m = 0.39) to H2O2 compared with ficin (K-m = 0.58), and ficin-TN had the highest K-cat which increased by 6.5 times and 4.5 times for TMB and H2O2, respectively. According to these findings, a colorimetric method with high sensitivity for the detection of biothiols was developed due to sulfhydryl compounds inhibited the peroxidase activity of ficin. Comparing with ficin and ficin-N, ficin-TN had the widest detection range (0.01-16 mu M) and the lowest detection limit (3 nM). The practical applications of ficin-TN for biothiol determination in human serum samples have been demonstrated with satisfactory results. Ficin-N and ficin-TN are promising to apply to the bioanalysis.
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Considering the significance of H2O2 to chemical industry and environmental security, it is meaningful to develop convenient and sensitive analytical methods for H2O2 detection under the harsh environment. Herein, a hollow porous ...
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Considering the significance of H2O2 to chemical industry and environmental security, it is meaningful to develop convenient and sensitive analytical methods for H2O2 detection under the harsh environment. Herein, a hollow porous N-doped carbon skeleton coated on the surface of Co4N nanoparticles (Co4N@NC) was obtained by pyrolysis of Co-MOF. Carbon coating and the hollow porous structure of Co4N@NC can not only stabilize Co4N NPs, but also promote the electron transfer between the active center and subtracts, affording Co4N@NC high catalytic activity and stability under harsh conditions (such as high temperature, acidic and basic conditions, high salt concentration). Co4N@NC shows excellent peroxidase-like activity and performs well in colorimetric analysis for H2O2 and glucose with a detection limit of 0.032 mu M and 0.29 mu M, respectively.
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The Au-Hg amalgam anchored on the surface of reduced graphene oxide nanosheets (Au-Hg/rGO) has been synthesized successfully and characterized by various techniques such as transmission electron microscopy, X-ray diffraction and X...
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The Au-Hg amalgam anchored on the surface of reduced graphene oxide nanosheets (Au-Hg/rGO) has been synthesized successfully and characterized by various techniques such as transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The Au-Hg/rGO nanocomposites were found to possess excellent peroxidase-like catalytic activity and can quickly catalyze the oxidation of colorless 3,3’,5,5’-tetramethylbenzidine (TMB) to blue oxTMB in the presence of H_2O_2. The obvious color change offered accurate determination of the H_2O_2 concentration by recording the absorbance at 652 nm using a UV-vis spectrophotometer. The linear response range for H_2O_2 was from 5 μM to 100 μM and the detection limit was 3.25 μM (S/N = 3). Furthermore, a kinetic study indicated that the catalytic behavior of Au-Hg/rGO nanocomposites followed the typical Michaelis-Menten theory and Au-Hg/rGO nanocomposites showed good affinity for H_2O_2. We envision that the simple and sensitive colorimetric detection system holds great promising applications in clinical diagnostics and food and environment monitoring.
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DNAzymes are catalytically active DNA molecules that can exhibit different enzymatic activities. DNA zymes can be superior to RNA and protein enzymes because they are less expensive to produce, easy to label and more stable agains...
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DNAzymes are catalytically active DNA molecules that can exhibit different enzymatic activities. DNA zymes can be superior to RNA and protein enzymes because they are less expensive to produce, easy to label and more stable against hydrolysis and heat treatment. For these reasons, the development of DNA zymes with diverse activities has attracted increasing interest.
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