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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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We discovered that random DNA fragments (RDF) could selectively catalyze the oxidation of peroxidase substrates under the H2O2-TMB system. The activity is closely related with the length of DNA chain. Taking advantage of simplicit...
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We discovered that random DNA fragments (RDF) could selectively catalyze the oxidation of peroxidase substrates under the H2O2-TMB system. The activity is closely related with the length of DNA chain. Taking advantage of simplicity and efficiency, the RDF would have potential applications in biotechnology and clinical diagnosis as enzymatic mimetics.
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Graphitic carbon nitride (g-C3N4) as a metal-free nanozyme has attracted huge attention for catalytic applications. However, the catalytic activity of pure g-C3N4 causes very moderate H2O2 activation. Herein, a novel three-dimensi...
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Graphitic carbon nitride (g-C3N4) as a metal-free nanozyme has attracted huge attention for catalytic applications. However, the catalytic activity of pure g-C3N4 causes very moderate H2O2 activation. Herein, a novel three-dimensional (3D) branched carbon nitride nanoneedle (3DBC-C3N4) nanozyme has been proposed to overcome such shortcoming. This unique 3D branched structure of 3DBC-C3N4 facilitated effective mass transfer during catalytic reaction and induced a lightning rodlike effect to accelerate electron collection at the tip area for H2O2 activation. With improved H2O2 activation for hydroxyl radical ((OH)-O-center dot) generation, 3DBC-C3N4 showed excellent peroxidase-like activity toward 3,3',5,5'-tetramethylbenzidine oxidation in the presence of H2O2. As for H2O2, the V-max value of 3DBC-C3N4 was found to be 20 times higher than that of natural horseradish peroxidase. Moreover, the 3D branched structure of 3DBC-C3N4 offered large interface for the reversible conjugation of single-stranded DNA, which enhanced the colorimetric sensitivity. Moreover, 3DBC-C3N4 exhibited high sensitivity toward oxytetracycline detection, with the detection limit and quantitative limit of 1 and 50 mu g/L, respectively.
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We have demonstrated a robust sensing strategy by employing single-stranded probe DNA and the hemin-graphene hybrid (GH) to detect a broad range of targets including metal ions, DNA and small molecules. This nearly "universal" bio...
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We have demonstrated a robust sensing strategy by employing single-stranded probe DNA and the hemin-graphene hybrid (GH) to detect a broad range of targets including metal ions, DNA and small molecules. This nearly "universal" biosensor approach is based on the DNA-mediated assembly of the hemin-graphene composite upon addition of the targets. Afterwards, GH aggregate resulting from DNA hybridization will occur. The DNA-GH hybrids will settle on the bottom of the vial after centrifugation, leaving behind a transparent supernatant. After incubation with TMB and H2O2, the colorimetric signal of the centrifugal supernatant will be significantly lower compared to that in the absence of targets. Therefore, mediation of the assembly of DNA on GH by targets can yield a facile means with tunable optical properties in response to concentration changes of the targets. This colorimetric "readout" offers great advantages such as the simple operation process, low-cost portable instrument and easy-to-use applications. Therefore, we believe that this method promises a great potential of becoming a routine tool for quantitative detection of a wide spectrum of analytes for specific applications in biodiagnostics, nanoelectronics, and bionanotechnology.
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Nanozymes,which combine the merits of both nanomaterials and natural enzymes,have aroused tremendous attention as new representatives of artificial enzyme mimics.However,it still remains to be a great challenge to rationally engin...
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Nanozymes,which combine the merits of both nanomaterials and natural enzymes,have aroused tremendous attention as new representatives of artificial enzyme mimics.However,it still remains to be a great challenge to rationally engineer the morphologies and surface properties of nanostructures that lead to the desired enzyme-like activities.Here,we report a DNA-programming seed-growth strategy to mediate the growth of platinum nanoparticles(PtNPs)on gold bipyramids(AuBPs)for the synthesis of a bimetallic nanozyme.We find that the preparation of a bimetallic nanozyme is in a sequence-dependent manner,and the encoding of a polyT sequence allows the successful formation of bimetallic nanohybrids with greatly enhanced peroxidase-like activity.We further observe that the morphologies and optical properties of T15-mediated Au/Pt nanostructures(Au/TlS/Pt)change over the reaction time,and the nanozymatic activity can be tuned by controlling the experimental conditions.As a concept application,Au/T15/Pt nanozymes are used to establish a simple,sensitive,and selective colorimetric assay for the determination of ascorbic acid(AA),alkaline phosphatase(ALP),and the inhibitor sodium vanadate(Na3V04),demonstrating excellent analytical performance.This work provides a new avenue for the rational design of bimetallic nanozymes for biosensing applications.
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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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Single atom nanozymes (SAzymes) represent the state-of-the-art technology in nanomaterial-based catalysis, which have attracted attentions in catalysis, cancer treatment, disinfection and biosensing fields. However, numerous SAzym...
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Single atom nanozymes (SAzymes) represent the state-of-the-art technology in nanomaterial-based catalysis, which have attracted attentions in catalysis, cancer treatment, disinfection and biosensing fields. However, numerous SAzymes suffered from low aqueous dispersion and without recognition capacity, which impeded their applications in bioanalysis. Herein, we engineered DNA onto SAzymes to obtain the DNA/SAzymes conjugates, which significantly improved the aqueous dispersion and recognition ability of SAzymes. We synthesized iron SAzymes (Fe-N-C SAzymes) as the catalytic nanomaterials, and investigated the interactions between Fe-N-C SAzymes and DNA. We compared A(15), T-15 and C-15 adsorption of Fe-N-C SAzymes in HEPES containing 2 mM MgCl2. We found that 50 mg mL(-1) Fe-N-C SAzymes produced nearly 100% A(15) adsorption, 90% T-15 adsorption and only 69% C-15 adsorption, indicating that adenine and thymine had higher adsorption affinity on Fe-N-C SAzymes. More importantly, DNA modification did not affect the peroxidase-like activity of Fe-N-C SAzymes and the bioactivity of the adsorbed DNA. Taking the advantage of the diblock DNA with one DNA sequence (adenine) binding to Fe-N-C SAzymes and the other DNA sequence (i.e., aptamer) binding to cancer cells, we designed Apt/Fe-N-C SAzymes for colorimetric detection of cancer cells, which offered new insights for the use of SAzymes in biomedicine. (C) 2021 Elsevier B.V. All rights reserved.
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Bridging-induced aggregation of individual nanozyme particles by long-chain biomacromolecules causes loss of peroxidase mimetic activity for various nanozymes. When a common nanozyme (Fe3O4 nanoparticles) was used for calorimetric...
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Bridging-induced aggregation of individual nanozyme particles by long-chain biomacromolecules causes loss of peroxidase mimetic activity for various nanozymes. When a common nanozyme (Fe3O4 nanoparticles) was used for calorimetric assay of a long-chain biomacromolecule, human genomic DNA (hgDNA, 14.000 kDa, containing 22 kilobases), peroxidase-like activity was absent owing to the irreversible aggregation of Fe3O4 nanoparticles in the presence of hgDNA. We synthesized an aggregation-resistant nanozyme containing Fe3O4 nanoparticles immobilized in 5.1 mu m monodisperse-porous silica microspheres. Fe3O4 nanoparticles were immobilized in a form accessible to the substrate and large biomolecules in the solution within the monodispersed silica microspheres including both mesopores and macropores. An appreciable and stable spectrophotometric response was obtained, originating from the satisfactorily high peroxidase-like activity of the synthesized nanozyme. No aggregation was observed in the aqueous dispersion of the nanozyme in the presence of hgDNA. Large particle size, low particle number density, high surface area, and the presence of macropores were evaluated as factors contributing to the adsorption of hgDNA chains onto the synthesized nanozyme without interparticle bridge formation between the individual microspheres causing aggregation. Here, for the first time a calorimetric assay was developed based on the enhancement of peroxidase-mimetic activity of non-aggregated porous silica microspheres to determine hgDNA concentration up to 300 ng/mu L. hgDNA could be also isolated with 47% yield and an equilibrium hgDNA adsorption of 19.000 ng/mg, using the same nanozyme. Hence, a material acting as a nanozyme for colorimetric determination of hgDNA was also evaluated as a magnetic, solid phase extraction sorbent for the first time. (C) 2019 Elsevier Inc. All rights reserved.
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Complex (Et3HN)[Fe-III(bpb)Cl-2], I {where H(2)bpb: N,N'-(1,2-phenylene)bis(pyridine-2-carboxamide)) was synthesized and characterized by reported procedure (Yang et al., 1991). Complex 1 was found to be effective in superoxide sc...
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Complex (Et3HN)[Fe-III(bpb)Cl-2], I {where H(2)bpb: N,N'-(1,2-phenylene)bis(pyridine-2-carboxamide)) was synthesized and characterized by reported procedure (Yang et al., 1991). Complex 1 was found to be effective in superoxide scavenging activity and an IC50 value of 4.1 mu M was obtained in xanthine-xanthine oxidase nitro blue tetrazolium assay. Peroxidase-like activity of this complex was determined by the oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS). DNA interaction studies of complex 1 showed binding of DNA through external or groove binding. Complex I exhibited chemical nuclease activity in the presence of hydrogen peroxide and cleaved supercoiled pBR322 DNA to its linear and nicked circular form at physiological pH. Mechanistic studies indicated possible role of hydroxyl radical ((OH)-O-center dot) species in DNA cleavage activity via hydroperoxo intermediate: [Fe-III-OOH-](2+) -> [Fe-IV=O](2+) + (OH)-O-center dot. (C) 2015 Elsevier B.V. All rights reserved.
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