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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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Nanozyme-based tumor catalytic therapy has attracted widespread attention in recent years. However, its therapeutic outcomes are diminished by many factors in the tumor microenvironment (TME), such as insufficient endogenous hydro...
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Nanozyme-based tumor catalytic therapy has attracted widespread attention in recent years. However, its therapeutic outcomes are diminished by many factors in the tumor microenvironment (TME), such as insufficient endogenous hydrogen peroxide (H2O2) concentration, hypoxia, and immunosuppressive microenvironment. Herein, an immunomodulation-enhanced nanozyme-based tumor catalytic therapy strategy is first proposed to achieve the synergism between nanozymes and TME regulation. TGF-beta inhibitor (TI)-loaded PEGylated iron manganese silicate nanoparticles (IMSN) (named as IMSN-PEG-TI) are constructed to trigger the therapeutic modality. The results show that IMSN nanozyme exhibits both intrinsic peroxidase-like and catalase-like activities under acidic TME, which can decompose H(2)O(2)into hydroxyl radicals (center dot OH) and oxygen (O-2), respectively. Besides, it is demonstrated that both IMSN and TI can regulate the tumor immune microenvironment, resulting in macrophage polarization from M2 to M1, and thus inducing the regeneration of H2O2, which can promote catalytic activities of IMSN nanozyme. The potent antitumor effect of IMSN-PEG-TI is proved by in vitro multicellular tumor spheroids (MCTS) and in vivo CT26-tumor-bearing mice models. It is believed that the immunomodulation-enhanced nanozyme-based tumor treatment strategy is a promising tool to kill cancer cells.
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Smart supramolecular nanoenzymes with temperature- driven switching property have been successfully constructed by the self-assembly of supra-amphiphiles formed by the cyclodextrin- based host-guest chemistry. The self-assembled n...
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Smart supramolecular nanoenzymes with temperature- driven switching property have been successfully constructed by the self-assembly of supra-amphiphiles formed by the cyclodextrin- based host-guest chemistry. The self-assembled nanostructures were catalyst-functionalized and thermosensitively-functionalized through conveniently linking the catalytic center of glutathione peroxidase and thermosensitive polymer to the host cyclodextrin molecules.The ON-OFF switches for the peroxidase activity by reversible transformation of nanostructures from tube to sphere have been achieved through changing the temperature. We anticipate that such intelligent enzyme mimics could be developed to use in an antioxidant medicine with controlled catalytic efficiency according to the needs of the human body in the future.
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The catalytic performance of gold (Au) decorated cerium oxide nanoparticles (nanoceria) can be potentially crucial because such a defined arrangement of multiple materials may provide improved chemical and biological catalytic act...
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The catalytic performance of gold (Au) decorated cerium oxide nanoparticles (nanoceria) can be potentially crucial because such a defined arrangement of multiple materials may provide improved chemical and biological catalytic activities. In this work, we have utilized a highly localized approach to reduce Au nanoparticles (AuNPs) on the nanoceria-phosphotungstate composite's surface. Phosphotungstic acid (PTA) bound on nanoceria' s surface acts as a UV-light dependent redox molecule that specifically reduces AuNPs. The mechanistic study demonstrates that PTA* molecules outstanding electron transfer ability leads to an excellent improvement in the catalytic performance of nanoceria-PTA*-AuNPs composite. Nanoceria-PTA*-AuNPs showed better and faster degradation of 4-nitrophenol than either nanoceria or PTA*-AuNPs. The developed nanoceria-PTA*-AuNPs exhibited efficient (>80 % in 5 min) conversion of 4-NP into 4-AP at room temperature and neutral pH. Additionally, the nanoceria-PTA*-AuNPs also showed improved pemxidase enzyme-like activity than the corresponding control samples. The observed catalytic activity could be due to the rapid electron transfer from nanoceria to AuNPs, where the metal nanoparticle acts as an electron sink, mediated by PTA*. Nanoceria-PTA*AuNPs showed similar to 2-fold better catalytic oxidation of peroxidase substrate than PTA*-AuNPs. The reported nanoceria-PTA*-AuNPs nanocomposites are expected to display improved biological enzyme-like activities, photocatalysis, and other biomedical applications.
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The present study measures the effect of citrate-coated magnetite nanoparticles (Fe_3O_4-NPs) on the germination and early growth of Quercus macdougallii (oak). Two types of Fe_3O_4-NPs were synthetized and characterized, being de...
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The present study measures the effect of citrate-coated magnetite nanoparticles (Fe_3O_4-NPs) on the germination and early growth of Quercus macdougallii (oak). Two types of Fe_3O_4-NPs were synthetized and characterized, being denominated NP1 and NP2. The synthesis was performed by the co-precipitation method and partial reduction of iron(Ⅱ), respectively. It was found that the NP1 has a quasi-spherical morphology, with sizes of 6-10 nm, while the NP2 has sizes between 65 and 160 nm. It was demonstrated that the Fe_3O_4-NPs exhibit perox-idase-like catalytic activity. Experiments of germination and growth of Quercus macdougallii were performed using the synthesized Fe_3O_4-NPs treatments and a deionized water control. The experiments were performed in intact and peeled acorns. The application of the NPs increased the germination up to 33% in relation to the control. Additionally, the Fe_3O_4-NPs treatments increased the growth, dry biomass, and chlorophyll concentration. The data obtained in this study suggest that Fe_3O_4-NPs treatments could be potentially used to improve conservation and reforestation of threatened forestry species.
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With the assistance of NH4VO3 and surfactant PEG-400, a new Keggin-type polyoxometalates (POMs) based Zn-organic framework (Zn-MOF), [Zn(H2O)(bpe)(H3PW12O40)]2bpe center dot 2H(2)O (Zn(bpe)PW12, bpe = 1,2-bis (4-pyridyl) ethylene)...
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With the assistance of NH4VO3 and surfactant PEG-400, a new Keggin-type polyoxometalates (POMs) based Zn-organic framework (Zn-MOF), [Zn(H2O)(bpe)(H3PW12O40)]2bpe center dot 2H(2)O (Zn(bpe)PW12, bpe = 1,2-bis (4-pyridyl) ethylene), was successfully synthesized by the surfactant-assisted solvothermal method. Single crystal X-ray diffraction analysis reveals that compound Zn(bpe)PW12 exhibits a fascinating pseudo three-dimensional POM-pillared Zn-MOFs containing left- and right-handed helical chains, and the total accessible volume is 11.17%. More importantly, the peroxidase-like activities of Zn(bpe)PW12 as one kind of POMOFs containing Zn element was studied for the first time, and the results show that the title compound Zn(bpe)PW12 exhibits excellent peroxidase-like activity including selectivity, anti-interference, stability, and reproducibility.
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Magnetic nanofibrous composite membranes were electrospun from the mixtures of poly(acrylonitrile-co-acrylic acid) (PANCAA) and Fe_3O_4 nanoparticles. Field emission scanning electron microscopy (FESEM) and thermal gravimetric ana...
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Magnetic nanofibrous composite membranes were electrospun from the mixtures of poly(acrylonitrile-co-acrylic acid) (PANCAA) and Fe_3O_4 nanoparticles. Field emission scanning electron microscopy (FESEM) and thermal gravimetric analysis (TGA) were used to characterize the composite membranes. TGA results indicate that the addition of Fe_3O_4 nanoparticles catalyzes the carbonization of PANCAA as well as dramatically increases the carbonization temperature. The intrinsic peroxidase-like activity of Fe_3O_4 nanoparticles was measured by the color reaction of phenol/4-amino antipyrine in the presence of H_2O_2. Under optimal conditions, the electrospun composite membranes show high peroxidase-like catalytic activity and reusability. Taking into account of the potentiality for separation, these as-prepared magnetic nanofibrous composite membranes will be applied in phenolic wastewater treatment.
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Au nanozymes are extensively researched for their photothermal effect and catalytic performance,but overcoming the inherent defects of poor dispersibility and thermal stability through complementary materials will expand their pro...
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Au nanozymes are extensively researched for their photothermal effect and catalytic performance,but overcoming the inherent defects of poor dispersibility and thermal stability through complementary materials will expand their prospects for biological applications.Herein,several novel CAu nanozymes were fabricated by in situ reduction of chloroauric acid on hollow carbon nanospheres(HCNs).Through regulating the number of reductions,sesame ball-shaped CAu(sCAu)with highly dispersed Au nanoparticles and diversity-shaped CAu(dCAu)were obtained.The number and morphology of loaded Au nanoparticles,absorption spectra,and hydrophilicity of CAu nanozymes were systematically characterized to demonstrate the flexibility of this novel method.The high-efficiency peroxidase-like sCAu0.3 nano-zyme with hyperthermia-activated property was then screened for later bio-application.It is worth mentioning that its photothermal-promoted peroxidase-like activity could be achieved under near-infrared laser irradiation.Moreover,sCAu0.3 could specifically achieve glutathione detection in human blood samples.This method will provide a protocol for the regulation of CAu nanozymes to adapt to bio-detection applications.
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In this report, carbon-based AuPd bimetallic nanocomposite (AuPd/C NC) was synthesized using carbon dots (C-dots) as the reducing agent and stabilizer by a simple green sequential reduction strategy, without adding other agents. T...
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In this report, carbon-based AuPd bimetallic nanocomposite (AuPd/C NC) was synthesized using carbon dots (C-dots) as the reducing agent and stabilizer by a simple green sequential reduction strategy, without adding other agents. The as synthesized AuPd/C NC showed good catalytic activity and peroxidase-like property. The structure and morphology of these nanoparticles were clearly characterized by UVeVis spectroscopy, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The AuPd/C NC catalyst exhibits noticeably higher catalytic activity than Pd and Au nanoparticles in catalysis reduction of 4-nitrophenol (4-NP). Moreover, based on the high peroxidase-like property of AuPd/C NC, a new colorimetric detection method for hydrogen peroxide (H2O2) has been designed using 3,3',5,5'-tetramethyl-benzidine (TMB) as the substrate, which provides a simple and sensitive means to detect H2O2 in wide linear range of 5 mu M-500 mu M and 500 mu M-4 mM with low detection limit of 1.6 mu M (S/N = 3). Therefore, the facile synthesis strategy for bimetallic nanoparticles by the mild reductant of carbon dot will provide some new thoughts for preparing of carbon-based metal nanomaterials and expand their application in catalysis and analytical chemistry areas. (C) 2016 Elsevier B.V. All rights reserved.
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Killing harmful bacteria in biofilms is a major challenge for current root canal therapy. Although traditional chemical disinfectants have a good bactericidal effect on plankton, they have little efficiency for the removal and ste...
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Killing harmful bacteria in biofilms is a major challenge for current root canal therapy. Although traditional chemical disinfectants have a good bactericidal effect on plankton, they have little efficiency for the removal and sterilization of bacterial biofilms, and even lead to the emergence of bacterial resistance and high toxic side effects. Herein, we propose for the first time biosafe nanocomposites that integrate photothermal and peroxidase-like catalytic activity for efficient removal and killing of bacterial biofilms in root canals. The integration of gold (core) and copper (Ⅰ, Ⅱ) sulfide (shell) shows excellent catalytic effect, which can catalyze the decomposition of hydrogen peroxide at biosafe concentrations to hydroxyl radicals for efficient removal of biofilms. Moreover, studies on the mechanism of antibiofilm showed that the nanocomposites (Au@Cu2-xS) have significant degradation effects on proteins and polysaccharides-the main components of biofilm. The in vitro results indicated that the synergism of free radical and heat shows higher sterilization rate against both gram-positive Enterococcus faecalis and gram-negative Fusobacterium nucleus, compared with free radical and heat treatment alone. More importantly, the bactericidal results on isolated dental slices and in root canal models and beagle dog demonstrated the Au@Cu2-xS is highly effective in inactivating the bacteria in biofilms. Hence this safe and synergistic antimicrobial system has great potential in antibiofilm-oriented root canal therapy.
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