摘要 :
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...
展开
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.
收起
摘要 :
Glutathione (GSH), the most abundant biothiol in cells, not only plays a pivotal role in protective and detoxifying functions of the cell, but also serves as a very important mediator in many cellular functions. Especially, the di...
展开
Glutathione (GSH), the most abundant biothiol in cells, not only plays a pivotal role in protective and detoxifying functions of the cell, but also serves as a very important mediator in many cellular functions. Especially, the difference of GSH level between cancer cells and normal cells is regarded as one of most important physiological parameters for cancer diagnosis. It is thereby extremely necessary to develop a simple, sensitive, and reliable analytical method for detection of GSH in cells. On the basis of the inhibition effect of GSH on the peroxidase-like activity of GSH stabilized gold nanoclusters, here a novel and facile strategy for colorimetric detection of cellular GSH level was well established. In this sensing system, GSH can effectively inhibit the oxidation of peroxidase substrate 3,3 ',5,5 '-tetramethylbenzidine (TMB) to produce a blue colored product. Under the optimized conditions, the absorbance at 652 nm against GSH concentration shows a linear relationship within a range from 2 to 25 mu M with detection limit of 420 nM. This excellent property allows our approach to be used to accurately evaluate the cellular GSH levels, and it is revealed that the overall GSH level in cancer cells was much higher than that in normal cells. The presented assay will enable a powerful tool for identifying cancer cells in a simple manner for biomedical diagnosis associated with GSH. (C) 2017 Elsevier B. V. All rights reserved.
收起
摘要 :
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...
展开
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.
收起
摘要 :
Zeolitic imidazole framework-67 (ZIF-67) was demonstrated to exhibit intrinsic peroxidase-like activity by using 3,3',5,5'-tetramethylbenzidine (TMB) as a chromogenic substrate. However, due to the inherent defects in the chemical...
展开
Zeolitic imidazole framework-67 (ZIF-67) was demonstrated to exhibit intrinsic peroxidase-like activity by using 3,3',5,5'-tetramethylbenzidine (TMB) as a chromogenic substrate. However, due to the inherent defects in the chemical stability and thermal stability of ZIFs, the peroxidase-like activity of ZIF-67 was severely affected. Therefore, establishing a simple and effective method to enhance the stability of ZIF-67 is necessary. ATP was found to improve die catalytic activity of ZIF-67. On the one hand, compared with ZIF-67, the catalytic efficiency of ZIF-67/ATP increased by 796 %, 5010 % and 570 % at 25 0C, 30 0C and 40 0C, respectively. In addition, die catalytic activity of ZIF-67/ATP was also greatly enhanced at pH-4. On the otiier hand, compared witii ATP, die catalytic rate of ZIF-67/ATP increased by 364 % after 10 min of incubation. Inspired by die high catalytic activity of ZIF-67/ATP, we used the ZIF-67/ATP peroxidase-like system for colorimetrie detection of glutathione with the limit of detection (LOD) of 0.46 uM. Furthermore, the proposed method provides a perspective on stabilizing the structures of ZIFs and developing a simple and efficient detection method.
收起
摘要 :
Chronic wounds caused by bacterial infections are a major challenge in
medical fields. The hypoxia condition extremely induces reactive oxygen
species (ROS) generation and upregulates the expression of hypoxia-inducible
factor,...
展开
Chronic wounds caused by bacterial infections are a major challenge in
medical fields. The hypoxia condition extremely induces reactive oxygen
species (ROS) generation and upregulates the expression of hypoxia-inducible
factor, both of which can increase the pro-inflammatory M1 subtype
macrophages production while reducing the anti-inflammatory M2 subtype
macrophages. Besides, bacteria-formed biofilms can hinder the penetration of
therapeutic agents. Encouraged by natural motors automatically executing
tasks, hypothesized that supplying sufficient oxygen (O_2) would
simultaneously drive therapeutic agent movement, rescue the hypoxic
microenvironment, and disrupt the vicious cycle of inflammation. Here, small
organic molecule-based nanoparticles (2TT-mC6B@Cu_(5.4)O NPs) that possess
high photothermal conversion efficiency and enzymatic activities are
developed, including superoxide dismutase-, catalase-, and glutathione
peroxidase-like activity. 2TT-mC6B@Cu_(5.4)O NPs exhibit superior
ROS-scavenging and O_2 production abilities that synergistically relieve
inflammation, alleviate hypoxia conditions, and promote their deep
penetration in chronic wound tissues. Transcriptome analysis further
demonstrates that 2TT-mC6B@Cu5.4O NPs inhibit biological activities inside
bacteria. Furthermore, in vivo experiments prove that 2TT-mC6B@Cu_(5.4)O
NPs-based hyperthermia can effectively eliminate bacteria in biofilms to
promote wound healing.
收起
摘要 :
Carbon quantum dots (CQDs) were prepared from wood soot, and the CQDs could catalyze the oxidation of 3, 3′, 5, 5′-tetramethylbenzidine (TMB) in the presence of H2O2to form oxidized TMB (ox-TMB) with an absorption peak at 652 n...
展开
Carbon quantum dots (CQDs) were prepared from wood soot, and the CQDs could catalyze the oxidation of 3, 3′, 5, 5′-tetramethylbenzidine (TMB) in the presence of H2O2to form oxidized TMB (ox-TMB) with an absorption peak at 652 nm. It was found that the introduction of glutathione (GSH) could cause the reduction of ox-TMB, resulting in a decrease of the absorbance at 652 nm. Based on this, a highly sensitive colorimetric sensor for detection of GSH was fabricated. The influences of various experimental variables, including pH, temperature, and the concentrations of H2O2, CQDs and TMB, on the analytical performance of the method were systematically investigated. Under the conditions of pH 3.5, temperature 35 °C, H2O21.0 mM, CQDs 2.5 μg/mL and TMB 0.5 mM, the response was linearly proportional to the concentration of GSH within the range of 0.05 to 20 μM with a low detect limit (3 σ/k) of 0.016 μM. The method was successfully applied to determination of GSH in human serum samples with the recovery of 95.7%–103.6%.
收起
摘要 :
A novel strategy for design of haptens that were used to produce catalytic antibodies was developed and three monoclonal antibodies, 3G5, 2F3, and 5C9, were generated using this strategy. These monoclonal antibodies were converted...
展开
A novel strategy for design of haptens that were used to produce catalytic antibodies was developed and three monoclonal antibodies, 3G5, 2F3, and 5C9, were generated using this strategy. These monoclonal antibodies were converted into selenium-containing abzymes by chemically modifying the hydroxyl group of serines followed by sodium hydrogen selenide displacement. These selenium-containing abzymes exhibited remarkable glutathione peroxidase activity, which surpasses the activity of some native glutathione peroxidases. The activities of the selenium-containing abzymes Se-3G5, Se-2F3, and Se-5C9 which catalyzed reduction of hydroperoxides by glutathione were 2.23, 4.20, and 3.79 times that of rabbit liver glutathione peroxidase, respectively. Detailed steady-state kinetics study on Se-2F3 was carried out and the value of k(cat)/K-m (H2O2) was found to be 2.11 X 10(7) M-1 min(-1) which was supposed to be one of the highest among the known catalytic antibodies. The data of association constants and glutathione peroxidase activities of these catalytic antibodies and the steady-state kinetics of Se-2F3 showed that the method might be a remarkably efficient one for generating catalytic antibodies with glutathione peroxidase activity.
收起
摘要 :
An eco-friendly and economic efficient approach has been developed for the photoinduced synthesis of more stable AuNPs using an aqueous extract of Croton bonplandianum (AEC) as a reducing and capping agent. The reaction mixture of...
展开
An eco-friendly and economic efficient approach has been developed for the photoinduced synthesis of more stable AuNPs using an aqueous extract of Croton bonplandianum (AEC) as a reducing and capping agent. The reaction mixture of AEC and HAuCl4 center dot xH(2)O, when exposed to sunlight turned purple which primarily confirmed the biosynthesis of AuNPs. The biosynthesis was monitored using UV-vis spectroscopy which exhibited a sharp SPR band at 530 nm after 16 min of sunlight exposure. The parameters affecting the synthesis of AuNPs such as sunlight exposure, AEC inoculum dose, and HAuCl4 center dot xH(2)O concentration were also optimized. The HR-TEM study revealed that, as the metal ion concentrations increased, the average size and anisotropic nature of the AuNPs increased. The X-ray diffraction pattern of AuNPs synthesized confirmed the formation of face-centered cubic crystal lattice of metallic gold. The involvement of polyphenolics in the synthesis of AuNPs was confirmed by comparing the FTIR analysis of pure tannic acid, AEC, and pre- and postannealed AuNPs. The XPS analysis corroborated the presence of two individual peaks attributed to the Au 4f(7/2) and Au 4f(5/2) binding energies which corresponded to the presence of metallic gold. The AuNPs thus obtained showed peroxidase-like mimicking activity which catalyzed the oxidation of TMB to oxTMB with the development of blue color and absorption spectra at 652 nm. However, the presence of GSH caused further reduction of oxTMB. This detection experiment showed an excellent linear relationship between 1 and 40 mu M with a limit of detection of 0.013 mu M. In addition to this, the significant recovery of GSH from human blood serum advocated that the developed system was simple and sensitive for the real sample analysis.
收起
摘要 :
The sensitive and facile detection of the concentration of glucose and glutathione (GSH) is important for our health. In this work, lily polysaccharide (LP) stabilized platinum nanoclusters (Ptn-LP NCs) were prepared by a facile s...
展开
The sensitive and facile detection of the concentration of glucose and glutathione (GSH) is important for our health. In this work, lily polysaccharide (LP) stabilized platinum nanoclusters (Ptn-LP NCs) were prepared by a facile synthetic strategy where LP was used as a reducing agent and stabilizer. The successful preparation of 1-2 nm platinum nanoclusters (Pt NCs) inside of Ptn-LP NCs was confirmed using UV-Vis spectra, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and Transmission electron microscopy (TEM), respectively. Furthermore, Ptn-LP NCs accelerated the catalytic oxidation of colorless 3,3 ',5,5 ' tetramethylbenzidine (TMB) to blue oxidized TMB (oxTMB) in the presence of hydrogen peroxide (H2O2), indicating their intrinsic peroxidase-like activity. The Vm values of TMB and H2O2 were 50.3 x 10-8 Ms- 1 and 10.2 x 10-8 Ms- 1, respectively, which were higher than those of other mimetic enzymes. The peroxidase-like property of Ptn-LP NCs was used to sensitively detect the concentration of glucose and glutathione (GSH). The detection limits of glucose and GSH were as low as 1.89 and 0.37 mu M, the linear ranges of glucose and GSH were 2.5-1000 and 4-140 mu M, respectively. The colorimetric method was successfully applied to detect GSH concentration in human serum. This method has great potential application in bio-related detection in the future.
收起
摘要 :
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...
展开
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.
收起
原文获取