Nickel ferrite(NiFe_2O_4) nanoparticles have been dispersed in chitosan solution in order to fab ricate nanocomposite films.Horseradish peroxidase(HRP) has been immobilized onto this chitosan NiFe_2O_4 nanocomposite f...Nickel ferrite(NiFe_2O_4) nanoparticles have been dispersed in chitosan solution in order to fab ricate nanocomposite films.Horseradish peroxidase(HRP) has been immobilized onto this chitosan NiFe_2O_4 nanocomposite film via physical adsorption.The size of the NiFe_2O_4 nanoparticles has been estimated us ing X ray diffraction pattern and scanning electron microscopy(SEM) to be 40±9 nm.The chitosan NiFe_2O_4 nanocomposite film and HRP/chitosan NiFe_2O_4 bioelectrode have been characterized using SEM technique.The HRP/chitosan NiFe_2O_4 nanocomposite bioelectrode has a response time of 4 s,linearity as 0.3 to 12 m M of H2O2,sensitivity as 22 n A/m M.The effects of p H and the temperature of the immobilized HRP electrode have also been studied.展开更多
Objective To investigate the mechanisms of apoptosis induced in Human leukemia cell line K562 by the combination of indole-3-acetic acid and horseradish peroxidase.Methods Human leukemia cell line K562 were exposed to...Objective To investigate the mechanisms of apoptosis induced in Human leukemia cell line K562 by the combination of indole-3-acetic acid and horseradish peroxidase.Methods Human leukemia cell line K562 were exposed to indole-3-acetic acid（IAA） at 20,40,60,80 or 100mol/L and horseradish peroxidase（HRP） at 1.2g/mL for varying times.MTT assay was applied to detect the cell proliferation.Flow cytometry was performed to detect the arrest of cell cycle.Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling（TUNEL） assay was used to measure apoptosis.2,7-dichlorofluorescin diacetate（DCFH-DA） uptake was measured to determine free radical by confocal microscope.Content of malondiadehyde（MDA） and activity of superoxide dismutase（SOD） were measured by biochemical methods.Results IAA/HRP initiated growth inhibition of K562 cells in a dose-and time-dependent manner.Flow cytometry revealed that cell cycle arrested at G1/G0 after 24 hours treatment.After 72 hours treatment,apoptotic rate of 100 mol/L IAA group increased to 43.9%,which was 5 times that of control（P<0.01）.Content of MDA and activity of SOD increased respectively in treatments compared with control.Meanwhile,IAA/HRP stimulated the formation of free radical,which was increased by IAA concentration-dependently.Conclusion The combination of IAA and HRP can inhibit the growth of Human leukemia cell line K562 in vitro by inducing apoptosis which is associated with the increase of free radical.The combination of IAA and HRP might be a promising chemopreventive and chemotherapeutic agent against human leukemia.展开更多
Horseradish peroxidase (HRP) is generally used as a label enzyme in enzyme immunoassay (EIA).The procedure used for HRP detection in EIA is critical for sensitivity and precision.This paper describes a novel fluorimet...Horseradish peroxidase (HRP) is generally used as a label enzyme in enzyme immunoassay (EIA).The procedure used for HRP detection in EIA is critical for sensitivity and precision.This paper describes a novel fluorimetric assay for horseradish peroxidase (HRP) using sesamol as substrate.The principle of the assay is as follow:sesamol (3,4-methylenedioxy phenol) is reacted enzymatically in the presence of hydrogen peroxide to produce dimeric sesamol.The dimer is fluorescent and can be detected sensitively at ex.347 nm,em.427 nm.The measurable range of HRP was 1.0×10-18 to 1.0×10-15 mol/assay,with a detection limit of 1.0×10-18 mol/assay.The coefficient of variation (CV,n=8) was examined at each point on the standard curve,with a mean CV percentage of 3.8%.This assay system was applied to thyroid stimulating hormone (TSH) EIA using HRP as the label enzyme.展开更多
Eriochrome black T and Nitrosulfophenol S were advocated as the chemical models of carcinogenic non-aminoazo compounds. The main products of their oxidative cleavage in horseradish peroxidase/H2O2 system was identifie...Eriochrome black T and Nitrosulfophenol S were advocated as the chemical models of carcinogenic non-aminoazo compounds. The main products of their oxidative cleavage in horseradish peroxidase/H2O2 system was identified as the benezenediazonium ion, the ultimate carcinogens, which could bind to DNA. The reaction conditions were investigated preliminarily. Some inhibitors and inducers of the reaction were discovered.展开更多
Mulit-enzyme cascades are a major type of chemical transformations and play a crucial role in biological signal transduction and metabolism. Herein, a trienzyme cascade-triggered fluorescent immunosensor platform was ...Mulit-enzyme cascades are a major type of chemical transformations and play a crucial role in biological signal transduction and metabolism. Herein, a trienzyme cascade-triggered fluorescent immunosensor platform was constructed by sequentially integrating alkaline phosphatase(ALP), tyrosinase(TYR)and horseradish peroxidase(HRP). The proposed platform was based on HRP-induced a rapid in situ fluorogenic reaction between dopamine(DA) and 1,5-dihydroxynaphthalene(DHA) to produce a strong yellow azamonardine fluorescent compound(AFC). The obtained AFC was clearly characterized by highresolution mass spectrum,1H NMR,^(13)C NMR and theoretical calculations. The integration of the twoenzyme system(TYR and HRP) or three-enzyme system(ALP, TYR and HRP) led to a maximum of 400.0-fold and 250.0-fold fluorescence enhancements, respectively. Using cardiac troponin I(c Tn I) as the model antigen, a trienzyme cascade-triggered fluorescent immunosensor platform was developed for quantitative detecting c Tn I in a wide linear range from 2 ng/m L to 150 ng/m L with a detection limit of 0.67ng/m L. In addition, the proposed platform was successfully applied in detection of c Tn I in serum of clinical patients. Overall, the developed fluorescent immunosensor performs powerful implications for researching enzyme cascade systems in the field of biomedicine.展开更多
The ternary system of dodecylpyridinium bromide(DDPB)/acetone/H2O with appropriate composition can form a gel spontaneously and the gel is stable in hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophos-...The ternary system of dodecylpyridinium bromide(DDPB)/acetone/H2O with appropriate composition can form a gel spontaneously and the gel is stable in hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophos-phate([Bmim]PF_(6)).Based on the gelation phenomenon we observed,the low molecular weight gelator(LMWG)was first tried to immobilize horseradish peroxidase(HRP)on glassy carbon electrode(GCE).The scanning elec-tron microscope(SEM)images,the UV-Vis spectra and the bioactivity measurement indicate that the gel is suitable for the immobilization of HRP.The direct electrochemistry of the HRP-gel modified GCE(HRP-gel/GCE)in[Bmim]PF_(6)shows a pair of well-defined and quasi-reversible redox peaks with the heterogeneous electron transfer rate constant(ks)being 14.4 s^(−1),indicating that the direct electron transfer between HRP and GCE is fast.The HRP-gel/GCE is stable and reproducible.Also the electrode exhibits good electrocatalytic effect on the reduction of trichloroacetic acid(TCA),showing good promise in bioelectrocatalysis.展开更多
Methanolic extracts from the leaves of <em>Manihot esculenta </em>(Two cultivars) and <em>Manihot glaziovii</em>, consumed as traditional vegetables in DR. Congo was chemically characterized by...Methanolic extracts from the leaves of <em>Manihot esculenta </em>(Two cultivars) and <em>Manihot glaziovii</em>, consumed as traditional vegetables in DR. Congo was chemically characterized by Thin layer Chromatography and High Performance Liquid Chromatography. <em>In vitro</em> biochemical activities of extracts against Radical Oxidative Species (ROS) production were assessed in cellular models, on enzymes, Myeloperoxidase (MPO) and Horseradish Peroxidase (HRP) involved in inflammation. The microscopic analysis of the powder of leaves showed that each species displays specific and discriminating botanical microscopic features. Varieties of<em> M. esculenta</em> had a chemical fingerprint different from <em>M. glaziovii</em>. The majority of compounds were polyphenols, represented mainly by rutin, kaempferol-3-O-rutinoside, amentoflavone, phenolic acids such as gallic acid. All extracts exhibited high cellular antioxidant activity in the range of 0.1 to 10 μg<span style="white-space:nowrap;">·</span>mL<sup>-1</sup> using lucigenin with neutrophils, but a moderate cellular antioxidant activity ranging between 10 and 100 μg<span style="white-space:nowrap;">·</span>mL<sup>-1</sup> with DCFDA on HL60 monocytes. Extracts from <em>Manihot</em> leaves showed a pronounced inhibitory effect on the production of extracellular ROS, on HRP and myeloperoxidase activity. Cellular antioxidant activities, the inhibitory effect on HRP of extracts from <em>M. glaziovii</em>, <em>M. esculenta</em> cultivar <em>Mwambu </em>were significantly higher, but their inhibitory effect on the activity of MPO was lower than those of <em>M. esculenta</em> cultivar TEM 419. The biological activities of <em>Manihot esculenta</em> and <em>Manihot glaziovii </em>were well correlated to their phytochemicals that could justify their traditional use as vegetables, potential functional foods or nutraceutical resources and medicines.展开更多
An amperometric hydrogen peroxide biosensor using a nanobiocomposite based on neutral red modified carbon nanotubes and co-immobilized glucose oxidase and horseradish peroxidase is reported. Modification of the nanobi...An amperometric hydrogen peroxide biosensor using a nanobiocomposite based on neutral red modified carbon nanotubes and co-immobilized glucose oxidase and horseradish peroxidase is reported. Modification of the nanobiocomposite electrode with neutral red resulted in a sensitive, low-cost and reliable H_2O_2 sensor. The use of carbon nanotubes, as the conductive part of the composite, facilitated fast electron transfer rates. The biosensor was characterized for the influence of p H, potential and temperature. A remarkable feature of the biosensor is the detection of H_2O_2 at low applied potentials where the noise level and interferences are minimal. The sensor has a fast steady-state measuring time of 10 s with a quick response(2 s). The biosensor showed a linear range from 15 n M to 45 m M of H_2O_2 and a detection limit of 5 n M. Nafion, which is used as a binder, makes the determination free from other electroactive substances. The repeatability, reproducibility,stability and analytical performance of the sensor are very good.展开更多
Phenolic compounds are among the major classes of pollutants produced by industrial and agricultural activities. The amperometric biosensors have been mainly applied to the determination of phenolic compounds because ...Phenolic compounds are among the major classes of pollutants produced by industrial and agricultural activities. The amperometric biosensors have been mainly applied to the determination of phenolic compounds because of the advantages such as good selectivity, low cost, and easy automation. Amperometry is a method to measure the electric current that flows as a result of reactions generated at the electrode. Amperometric phenol biosensors are most often based on tyrosinase, laccase or horseradish peroxidase immobilized on the electrode surface. The immobilization of enzymes into ordered thin materials has attracted considerable attention over the past few years. The present researches have demonstrated that biomolecules immobilized in different matrixes retain their functional characteristics to a large extent. These new materials are of great interest for applications as biosensors and biocatalysts. Lately, also conducting polymers have attracted much interest in the development of biological sensors. The electrically conducting polymers are known as possessing many interesting features, which allow them to act as excellent materials for immobilization of biomolecules.展开更多
Synthetic dyes are very important for textile dyeing,paper printing,color photography and petroleum products.Traditional methods of dye removal include biodegradation,precipitation,adsorption,chemical degradation,phot...Synthetic dyes are very important for textile dyeing,paper printing,color photography and petroleum products.Traditional methods of dye removal include biodegradation,precipitation,adsorption,chemical degradation,photo degradation,and chemical coagulation.Dye decolorization with enzymatic reaction is an important issue for several research field(chemistry,environment)In this study,minimum decolorization time of Remazol Brilliant Blue R dye with Horseradish peroxidase enzyme was calculated using with mathematical equation depending on experimental data.Dye decolorization was determined by monitoring the absorbance decrease at the specific maximum wavelength for dye.All experiments were carried out with different initial dye concentrations of Remazol Brilliant Blue R at 25 ℃ constant temperature for 30 minutes.The development of the least squares estimators for a nonlinear model brings about complications not encountered in the case of the linear model.Decolorization times for completely removal of dye were calculated according to equation.It was shown that mathematical equation was conformed exponential curve for dye degradation.展开更多
A novel solid-liquid-core fiber-optic biosensor was fabricated for highly sensitive and selective detection of 4-chlorophenol in water.The sensor comprised horseradish peroxidase(HRP)-coated U-shaped liquidcore optica...A novel solid-liquid-core fiber-optic biosensor was fabricated for highly sensitive and selective detection of 4-chlorophenol in water.The sensor comprised horseradish peroxidase(HRP)-coated U-shaped liquidcore optical fiber(LCOF)and 4-chlorophenol permselective polymer membrane.The U-shaped LCOF was flled with ethanol suspension of SiO_(2)particles and the polymer membrane was composed of molecularly imprinted polymer,sulfonated polyethersulfone,and polysulfone.The morphology,composition,and surface luminous properties of the sensing region were examined.The effects of the diameter and content of SiO_(2)particles and temperature of 4-chlorophenol solutions on the sensitivity of the biosensors were investigated.Further,the sensitivity,selectivity,response time,and limit of detection(LOD)of the biosensors was investigated.In addition,the effects of fiber core materials on the light transmission in sensing region were investigated and a biosensor sensing model was established.The proposed sensor exhibited high selectivity for 4-chlorophenol with satisfactory sensitivity,LOD,and response time:-1.18(μg/L)^(-1),30μg/L,and 400 s,respectively.The results are expected to aid in the development of methods for enhancing sensitivity of fiber-optic sensors and surface luminous intensity of optical fibers.展开更多
The enzyme hybrid nanoflower has gained interests in biosensors due to their simple synthesis and high efficiency.In this study,glutamate oxidase(GLOX)and horseradish peroxidase(HRP)hybrid nanoflowers(GLOX&HRP-HNF...The enzyme hybrid nanoflower has gained interests in biosensors due to their simple synthesis and high efficiency.In this study,glutamate oxidase(GLOX)and horseradish peroxidase(HRP)hybrid nanoflowers(GLOX&HRP-HNFs)were successfully prepared for the detection of glutamic acid(Glu).The effects of the synthesis conditions on the activity of GLOX&HRP-HNFs were investigated.Results revealed that the maximum activity of GLOX&HRP-HNFs was under 4 mM phosphate radical,2.5 mM MnSO4,0.04 mg/mL GLOX,and 0.16 mg/mL HRP.After immobilization,no significant differences were observed in optimum pH and temperature values of the GLOX and HRP.The GLOX&HRP-HNFs exhibited higher storage stability and resistance to organic solvents than free GLOX and HRP.Additionally,the GLOX&HRP-HNFs maintained 69%of its primary activity after 6 cycles.More important,the GLOX&HRP-HNFs exhibited a good linear range from 1 to 100μM(R^(2)=0.9979)and a low limit of detection(LOD)of 0.59μM for glutamate.These results suggest that the GLOX&HRP-HNFs is a promising candidate for applications in biosensing for the detection of glutamate.展开更多
A lack of biological activity hinders the application of synthetic hydrogels in tissue engineering and regenerative medicine.However,the use of glycopolypeptides in hydrogel synthesis may provide the materials with th...A lack of biological activity hinders the application of synthetic hydrogels in tissue engineering and regenerative medicine.However,the use of glycopolypeptides in hydrogel synthesis may provide the materials with the desired biological activities.Herein,we prepared three in situ-forming hydrogels from various phenol-functionalized glycopolypeptides.The gelation time,mechanical properties,degradation properties,and biocompatibility of the hydrogels were assessed.Gelation time ranged from 11 to 380s,depending on the concentration of horseradish peroxidase.The galactose-modified polypeptide hydrogel showed the highest storage modulus with an obvious stress relaxation phenomenon.The prepared hydrogels exhibited good degradation properties and compatibility to cells and tissues.Furthermore,the rate of immune cell accumulation around the mannosemodified polypeptide hydrogel was the fastest among the hydrogels.展开更多
Harmaline and harmine areβ-carboline alkaloids with effective pharmacological effects.Harmaline can be transformed into harmine after oral administration.However,enzymes involved in the metabolic pathway remain uncle...Harmaline and harmine areβ-carboline alkaloids with effective pharmacological effects.Harmaline can be transformed into harmine after oral administration.However,enzymes involved in the metabolic pathway remain unclear.In this study,harmaline was incubated with rat liver microsomes(RLM),rat brain microsomes(RBM),blood,plasma,broken blood cells,and heme peroxidases including horseradish peroxidase(HRP),lactoperoxidase(LPO),and myeloperoxidase(MPO).The production of harmine was determined by a validated UPLC-ESI-MS/MS method.Results showed that heme peroxidases catalyzed the oxidative dehydrogenation of harmaline.All the reactions were in accordance with the Hill equation.The reaction was inhibited by ascorbic acid and excess H_(2)0_(2).The transformation of harmaline to harmine was confirmed after incubation with blood,plasma,and broken blood cells,rather than RLM and RBM.Harmaline was incubated with blood,plasma,and broken cells liquid for 3 h,and the formation of harmine became stable.Results indicated an integrated metabolic pathway of harmaline,which will lay foundation for the oxidation reaction of dihydro-P-carboline.Moreover,the metabolic stability of harmaline in blood should not be ignored when the pharmacokinetics study of harmaline is carried out.展开更多
Foodborne pathogenic bacteria have been considered as a major risk factor for food safety. It is of great significance to carry out in-field screening of pathogenic bacteria to prevent the outbreaks of foodborne disea...Foodborne pathogenic bacteria have been considered as a major risk factor for food safety. It is of great significance to carry out in-field screening of pathogenic bacteria to prevent the outbreaks of foodborne diseases. In this study, a portable lab-on-a-disc platform with a microfluidic disc was developed for rapid and automatic detection of Salmonella typhimurium using a nickel nanowire(Ni NW) net for effective separation of target bacteria, horseradish peroxidase nanoflowers(HRP NFs) for efficient amplification of biological signals, and a self-developed smartphone APP for accurate analysis of colorimetric images. First,the microfluidic disc was preloaded with reagents and samples and centrifuged to form one bacterial sample column, one immune Ni NW column, one HRP NF column, two washing buffer columns and one tetramethylbenzidine(TMB) column, which were separated by air gaps. Then, a rotatable magnetic field was specifically developed to assemble the Ni NWs into a net, which was automatically controlled by a stepped motor to successively pass through the sample column for specific capture of target bacteria, the HRP NF column for specific label of target bacteria, the washing columns for effective removal of sample background and non-specific binding NFs, and the TMB column for colorimetric determination of target bacteria. The color change of TMB from colorless to blue was finally analyzed using the smartphone APP to quantitatively determine the target bacteria. This lab-on-a-disc platform could detect Salmonella typhimurium from 5.6 × 10^(1) CFU/20 μL to 5.6 × 10^(5) CFU/20 μL in 1 h with a lower detection limit of 56 CFU/20 μL. The recovery of target bacteria in spiked chicken samples ranged from 97.5% to 101.8%. This portable platform integrating separation, labeling, washing, catalysis and detection onto a single disc is featured with automatic operation, fast reaction, and small size and has shown its potential for in-field detection of foodborne pathogens.展开更多
Background:It is increasingly clear that in addition to myelin disruption,axonal degeneration may also represent a key pathology in multiple sclerosis(MS).Hence,elucidating the mechanisms of axonal degeneration may no...Background:It is increasingly clear that in addition to myelin disruption,axonal degeneration may also represent a key pathology in multiple sclerosis(MS).Hence,elucidating the mechanisms of axonal degeneration may not only enhance our understanding of the overall MS pathology,but also elucidate additional therapeutic targets.The objective of this study is assess the degree of axonal membrane disruption and its significance in motor deficits in EAE mice.Methods:Experimental Autoimmune Encephalomyelitis was induced in mice by subcutaneous injection of myelin oligodendrocyte glycoprotein/complete Freud’s adjuvant emulsion,followed by two intraperitoneal injections of pertussis toxin.Behavioral assessment was performed using a 5-point scale.Horseradish Peroxidase Exclusion test was used to quantify the disruption of axonal membrane.Polyethylene glycol was prepared as a 30%(w/v)solution in phosphate buffered saline and injected intraperitoneally.Results:We have found evidence of axonal membrane disruption in EAE mice when symptoms peak and to a lesser degree,in the pre-symptomatic stage of EAE mice.Furthermore,polyethylene glycol(PEG),a known membrane fusogen,significantly reduces axonal membrane disruption in EAE mice.Such PEG-mediated membrane repair was accompanied by significant amelioration of behavioral deficits,including a delay in the emergence of motor deficits,a delay of the emergence of peak symptom,and a reduction in the severity of peak symptom.Conclusions:The current study is the first indication that axonal membrane disruption may be an important part of the pathology in EAE mice and may underlies behavioral deficits.Our study also presents the initial observation that PEG may be a therapeutic agent that can repair axolemma,arrest axonal degeneration and reduce motor deficits in EAE mice.展开更多
基金the Fatih University,Research Project Foundation (Contract no:P500209022)Scientific and Technological Research Council of Turkey (TBTAK) (Pro ject no:110T487)TURKEY Prime Ministry State Planning Organization
文摘Nickel ferrite(NiFe_2O_4) nanoparticles have been dispersed in chitosan solution in order to fab ricate nanocomposite films.Horseradish peroxidase(HRP) has been immobilized onto this chitosan NiFe_2O_4 nanocomposite film via physical adsorption.The size of the NiFe_2O_4 nanoparticles has been estimated us ing X ray diffraction pattern and scanning electron microscopy(SEM) to be 40±9 nm.The chitosan NiFe_2O_4 nanocomposite film and HRP/chitosan NiFe_2O_4 bioelectrode have been characterized using SEM technique.The HRP/chitosan NiFe_2O_4 nanocomposite bioelectrode has a response time of 4 s,linearity as 0.3 to 12 m M of H2O2,sensitivity as 22 n A/m M.The effects of p H and the temperature of the immobilized HRP electrode have also been studied.
基金This work was supported by the Natural Science Foundation of Shaanxi Province(No.2003C215).
文摘Objective To investigate the mechanisms of apoptosis induced in Human leukemia cell line K562 by the combination of indole-3-acetic acid and horseradish peroxidase.Methods Human leukemia cell line K562 were exposed to indole-3-acetic acid（IAA） at 20,40,60,80 or 100mol/L and horseradish peroxidase（HRP） at 1.2g/mL for varying times.MTT assay was applied to detect the cell proliferation.Flow cytometry was performed to detect the arrest of cell cycle.Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling（TUNEL） assay was used to measure apoptosis.2,7-dichlorofluorescin diacetate（DCFH-DA） uptake was measured to determine free radical by confocal microscope.Content of malondiadehyde（MDA） and activity of superoxide dismutase（SOD） were measured by biochemical methods.Results IAA/HRP initiated growth inhibition of K562 cells in a dose-and time-dependent manner.Flow cytometry revealed that cell cycle arrested at G1/G0 after 24 hours treatment.After 72 hours treatment,apoptotic rate of 100 mol/L IAA group increased to 43.9%,which was 5 times that of control（P<0.01）.Content of MDA and activity of SOD increased respectively in treatments compared with control.Meanwhile,IAA/HRP stimulated the formation of free radical,which was increased by IAA concentration-dependently.Conclusion The combination of IAA and HRP can inhibit the growth of Human leukemia cell line K562 in vitro by inducing apoptosis which is associated with the increase of free radical.The combination of IAA and HRP might be a promising chemopreventive and chemotherapeutic agent against human leukemia.
文摘Horseradish peroxidase (HRP) is generally used as a label enzyme in enzyme immunoassay (EIA).The procedure used for HRP detection in EIA is critical for sensitivity and precision.This paper describes a novel fluorimetric assay for horseradish peroxidase (HRP) using sesamol as substrate.The principle of the assay is as follow:sesamol (3,4-methylenedioxy phenol) is reacted enzymatically in the presence of hydrogen peroxide to produce dimeric sesamol.The dimer is fluorescent and can be detected sensitively at ex.347 nm,em.427 nm.The measurable range of HRP was 1.0×10-18 to 1.0×10-15 mol/assay,with a detection limit of 1.0×10-18 mol/assay.The coefficient of variation (CV,n=8) was examined at each point on the standard curve,with a mean CV percentage of 3.8%.This assay system was applied to thyroid stimulating hormone (TSH) EIA using HRP as the label enzyme.
文摘Eriochrome black T and Nitrosulfophenol S were advocated as the chemical models of carcinogenic non-aminoazo compounds. The main products of their oxidative cleavage in horseradish peroxidase/H2O2 system was identified as the benezenediazonium ion, the ultimate carcinogens, which could bind to DNA. The reaction conditions were investigated preliminarily. Some inhibitors and inducers of the reaction were discovered.
基金the National Natural Science Foundation of China (Nos. 22174065, 21974119)the Science and Technology Planning Project of Hunan Province (No. 2020RC_(3)046)Hunan Provincial Natural Science Foundation of China (No.2019JJ30020)。
文摘Mulit-enzyme cascades are a major type of chemical transformations and play a crucial role in biological signal transduction and metabolism. Herein, a trienzyme cascade-triggered fluorescent immunosensor platform was constructed by sequentially integrating alkaline phosphatase(ALP), tyrosinase(TYR)and horseradish peroxidase(HRP). The proposed platform was based on HRP-induced a rapid in situ fluorogenic reaction between dopamine(DA) and 1,5-dihydroxynaphthalene(DHA) to produce a strong yellow azamonardine fluorescent compound(AFC). The obtained AFC was clearly characterized by highresolution mass spectrum,1H NMR,^(13)C NMR and theoretical calculations. The integration of the twoenzyme system(TYR and HRP) or three-enzyme system(ALP, TYR and HRP) led to a maximum of 400.0-fold and 250.0-fold fluorescence enhancements, respectively. Using cardiac troponin I(c Tn I) as the model antigen, a trienzyme cascade-triggered fluorescent immunosensor platform was developed for quantitative detecting c Tn I in a wide linear range from 2 ng/m L to 150 ng/m L with a detection limit of 0.67ng/m L. In addition, the proposed platform was successfully applied in detection of c Tn I in serum of clinical patients. Overall, the developed fluorescent immunosensor performs powerful implications for researching enzyme cascade systems in the field of biomedicine.
基金The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China(Nos.20973103,21173133)the National Basic Research Program of China(No.2011CB707400).
文摘The ternary system of dodecylpyridinium bromide(DDPB)/acetone/H2O with appropriate composition can form a gel spontaneously and the gel is stable in hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophos-phate([Bmim]PF_(6)).Based on the gelation phenomenon we observed,the low molecular weight gelator(LMWG)was first tried to immobilize horseradish peroxidase(HRP)on glassy carbon electrode(GCE).The scanning elec-tron microscope(SEM)images,the UV-Vis spectra and the bioactivity measurement indicate that the gel is suitable for the immobilization of HRP.The direct electrochemistry of the HRP-gel modified GCE(HRP-gel/GCE)in[Bmim]PF_(6)shows a pair of well-defined and quasi-reversible redox peaks with the heterogeneous electron transfer rate constant(ks)being 14.4 s^(−1),indicating that the direct electron transfer between HRP and GCE is fast.The HRP-gel/GCE is stable and reproducible.Also the electrode exhibits good electrocatalytic effect on the reduction of trichloroacetic acid(TCA),showing good promise in bioelectrocatalysis.
文摘Methanolic extracts from the leaves of <em>Manihot esculenta </em>(Two cultivars) and <em>Manihot glaziovii</em>, consumed as traditional vegetables in DR. Congo was chemically characterized by Thin layer Chromatography and High Performance Liquid Chromatography. <em>In vitro</em> biochemical activities of extracts against Radical Oxidative Species (ROS) production were assessed in cellular models, on enzymes, Myeloperoxidase (MPO) and Horseradish Peroxidase (HRP) involved in inflammation. The microscopic analysis of the powder of leaves showed that each species displays specific and discriminating botanical microscopic features. Varieties of<em> M. esculenta</em> had a chemical fingerprint different from <em>M. glaziovii</em>. The majority of compounds were polyphenols, represented mainly by rutin, kaempferol-3-O-rutinoside, amentoflavone, phenolic acids such as gallic acid. All extracts exhibited high cellular antioxidant activity in the range of 0.1 to 10 μg<span style="white-space:nowrap;">·</span>mL<sup>-1</sup> using lucigenin with neutrophils, but a moderate cellular antioxidant activity ranging between 10 and 100 μg<span style="white-space:nowrap;">·</span>mL<sup>-1</sup> with DCFDA on HL60 monocytes. Extracts from <em>Manihot</em> leaves showed a pronounced inhibitory effect on the production of extracellular ROS, on HRP and myeloperoxidase activity. Cellular antioxidant activities, the inhibitory effect on HRP of extracts from <em>M. glaziovii</em>, <em>M. esculenta</em> cultivar <em>Mwambu </em>were significantly higher, but their inhibitory effect on the activity of MPO was lower than those of <em>M. esculenta</em> cultivar TEM 419. The biological activities of <em>Manihot esculenta</em> and <em>Manihot glaziovii </em>were well correlated to their phytochemicals that could justify their traditional use as vegetables, potential functional foods or nutraceutical resources and medicines.
基金Department of Science and Technology(DST)Government of India,for sanctioning financial assistance for executing this programme under Nanomaterials Science and Technology Initiative Programmethe Council of Scientific and Industrial Research(CSIR),Government of India,for granting her fellowship for executing this programme
文摘An amperometric hydrogen peroxide biosensor using a nanobiocomposite based on neutral red modified carbon nanotubes and co-immobilized glucose oxidase and horseradish peroxidase is reported. Modification of the nanobiocomposite electrode with neutral red resulted in a sensitive, low-cost and reliable H_2O_2 sensor. The use of carbon nanotubes, as the conductive part of the composite, facilitated fast electron transfer rates. The biosensor was characterized for the influence of p H, potential and temperature. A remarkable feature of the biosensor is the detection of H_2O_2 at low applied potentials where the noise level and interferences are minimal. The sensor has a fast steady-state measuring time of 10 s with a quick response(2 s). The biosensor showed a linear range from 15 n M to 45 m M of H_2O_2 and a detection limit of 5 n M. Nafion, which is used as a binder, makes the determination free from other electroactive substances. The repeatability, reproducibility,stability and analytical performance of the sensor are very good.
基金Financial support from the Wroclaw University of Technology and Polish Ministry of Science and Higher Education Grant No.2012/05/B/ST5/00749
文摘Phenolic compounds are among the major classes of pollutants produced by industrial and agricultural activities. The amperometric biosensors have been mainly applied to the determination of phenolic compounds because of the advantages such as good selectivity, low cost, and easy automation. Amperometry is a method to measure the electric current that flows as a result of reactions generated at the electrode. Amperometric phenol biosensors are most often based on tyrosinase, laccase or horseradish peroxidase immobilized on the electrode surface. The immobilization of enzymes into ordered thin materials has attracted considerable attention over the past few years. The present researches have demonstrated that biomolecules immobilized in different matrixes retain their functional characteristics to a large extent. These new materials are of great interest for applications as biosensors and biocatalysts. Lately, also conducting polymers have attracted much interest in the development of biological sensors. The electrically conducting polymers are known as possessing many interesting features, which allow them to act as excellent materials for immobilization of biomolecules.
文摘Synthetic dyes are very important for textile dyeing,paper printing,color photography and petroleum products.Traditional methods of dye removal include biodegradation,precipitation,adsorption,chemical degradation,photo degradation,and chemical coagulation.Dye decolorization with enzymatic reaction is an important issue for several research field(chemistry,environment)In this study,minimum decolorization time of Remazol Brilliant Blue R dye with Horseradish peroxidase enzyme was calculated using with mathematical equation depending on experimental data.Dye decolorization was determined by monitoring the absorbance decrease at the specific maximum wavelength for dye.All experiments were carried out with different initial dye concentrations of Remazol Brilliant Blue R at 25 ℃ constant temperature for 30 minutes.The development of the least squares estimators for a nonlinear model brings about complications not encountered in the case of the linear model.Decolorization times for completely removal of dye were calculated according to equation.It was shown that mathematical equation was conformed exponential curve for dye degradation.
基金support from the National Natural Science Foundation of China(NSFC)(Nos.U19A20107,52176178 and 51876018)Innovation Research Group of Universities in Chongqing(No.CXQT21035)+1 种基金Chongqing Natural Science Foundation Innovation and Development Joint Fund Project(No.CSTB2022NSCQ-LZX0059)the Scientific and Technological Research Program of Chongqing Municipal Education Commission of China(No.KJZD-M202201101).
文摘A novel solid-liquid-core fiber-optic biosensor was fabricated for highly sensitive and selective detection of 4-chlorophenol in water.The sensor comprised horseradish peroxidase(HRP)-coated U-shaped liquidcore optical fiber(LCOF)and 4-chlorophenol permselective polymer membrane.The U-shaped LCOF was flled with ethanol suspension of SiO_(2)particles and the polymer membrane was composed of molecularly imprinted polymer,sulfonated polyethersulfone,and polysulfone.The morphology,composition,and surface luminous properties of the sensing region were examined.The effects of the diameter and content of SiO_(2)particles and temperature of 4-chlorophenol solutions on the sensitivity of the biosensors were investigated.Further,the sensitivity,selectivity,response time,and limit of detection(LOD)of the biosensors was investigated.In addition,the effects of fiber core materials on the light transmission in sensing region were investigated and a biosensor sensing model was established.The proposed sensor exhibited high selectivity for 4-chlorophenol with satisfactory sensitivity,LOD,and response time:-1.18(μg/L)^(-1),30μg/L,and 400 s,respectively.The results are expected to aid in the development of methods for enhancing sensitivity of fiber-optic sensors and surface luminous intensity of optical fibers.
基金This work was partially supported by the Open Project Program of State Key Laboratory of Food Nutrition and Safety,Tianjin University of Science&Technology(project No.SKLFNS-KF-202203)Dr.J.D.Cui thanks support from the Science and Technology Program of Tianjin,China(project No.20ZYJDJC00080)the international collaboration project(grant No.2020/37/K/ST8/03805).
文摘The enzyme hybrid nanoflower has gained interests in biosensors due to their simple synthesis and high efficiency.In this study,glutamate oxidase(GLOX)and horseradish peroxidase(HRP)hybrid nanoflowers(GLOX&HRP-HNFs)were successfully prepared for the detection of glutamic acid(Glu).The effects of the synthesis conditions on the activity of GLOX&HRP-HNFs were investigated.Results revealed that the maximum activity of GLOX&HRP-HNFs was under 4 mM phosphate radical,2.5 mM MnSO4,0.04 mg/mL GLOX,and 0.16 mg/mL HRP.After immobilization,no significant differences were observed in optimum pH and temperature values of the GLOX and HRP.The GLOX&HRP-HNFs exhibited higher storage stability and resistance to organic solvents than free GLOX and HRP.Additionally,the GLOX&HRP-HNFs maintained 69%of its primary activity after 6 cycles.More important,the GLOX&HRP-HNFs exhibited a good linear range from 1 to 100μM(R^(2)=0.9979)and a low limit of detection(LOD)of 0.59μM for glutamate.These results suggest that the GLOX&HRP-HNFs is a promising candidate for applications in biosensing for the detection of glutamate.
基金supported by the National Natural Science Foundation of China(Grant Nos.2157412751622307+3 种基金5152010500451833010 and51773199)the Youth Innovation Promotion AssociationCAS。
文摘A lack of biological activity hinders the application of synthetic hydrogels in tissue engineering and regenerative medicine.However,the use of glycopolypeptides in hydrogel synthesis may provide the materials with the desired biological activities.Herein,we prepared three in situ-forming hydrogels from various phenol-functionalized glycopolypeptides.The gelation time,mechanical properties,degradation properties,and biocompatibility of the hydrogels were assessed.Gelation time ranged from 11 to 380s,depending on the concentration of horseradish peroxidase.The galactose-modified polypeptide hydrogel showed the highest storage modulus with an obvious stress relaxation phenomenon.The prepared hydrogels exhibited good degradation properties and compatibility to cells and tissues.Furthermore,the rate of immune cell accumulation around the mannosemodified polypeptide hydrogel was the fastest among the hydrogels.
基金supported by the National Natural Science Foundation of China(Nos.82173885 and 81872933)the National Natural Science Foundation of Xinjiang Uyghur Autonomous Region of China(No.U1130303)+1 种基金the Technology Cooperation Projects of Science in Shanghai,China(No.20015800100)the Key Laboratory Open Project of Xinjiang Uyghur Autonomous Region(No.2019D04018).
文摘Harmaline and harmine areβ-carboline alkaloids with effective pharmacological effects.Harmaline can be transformed into harmine after oral administration.However,enzymes involved in the metabolic pathway remain unclear.In this study,harmaline was incubated with rat liver microsomes(RLM),rat brain microsomes(RBM),blood,plasma,broken blood cells,and heme peroxidases including horseradish peroxidase(HRP),lactoperoxidase(LPO),and myeloperoxidase(MPO).The production of harmine was determined by a validated UPLC-ESI-MS/MS method.Results showed that heme peroxidases catalyzed the oxidative dehydrogenation of harmaline.All the reactions were in accordance with the Hill equation.The reaction was inhibited by ascorbic acid and excess H_(2)0_(2).The transformation of harmaline to harmine was confirmed after incubation with blood,plasma,and broken blood cells,rather than RLM and RBM.Harmaline was incubated with blood,plasma,and broken cells liquid for 3 h,and the formation of harmine became stable.Results indicated an integrated metabolic pathway of harmaline,which will lay foundation for the oxidation reaction of dihydro-P-carboline.Moreover,the metabolic stability of harmaline in blood should not be ignored when the pharmacokinetics study of harmaline is carried out.
基金supported by National Natural Science Foundation of China (No. 32071899)Walmart Foundation (No.61626817)Walmart Food Safety Collaboration Center for its great support。
文摘Foodborne pathogenic bacteria have been considered as a major risk factor for food safety. It is of great significance to carry out in-field screening of pathogenic bacteria to prevent the outbreaks of foodborne diseases. In this study, a portable lab-on-a-disc platform with a microfluidic disc was developed for rapid and automatic detection of Salmonella typhimurium using a nickel nanowire(Ni NW) net for effective separation of target bacteria, horseradish peroxidase nanoflowers(HRP NFs) for efficient amplification of biological signals, and a self-developed smartphone APP for accurate analysis of colorimetric images. First,the microfluidic disc was preloaded with reagents and samples and centrifuged to form one bacterial sample column, one immune Ni NW column, one HRP NF column, two washing buffer columns and one tetramethylbenzidine(TMB) column, which were separated by air gaps. Then, a rotatable magnetic field was specifically developed to assemble the Ni NWs into a net, which was automatically controlled by a stepped motor to successively pass through the sample column for specific capture of target bacteria, the HRP NF column for specific label of target bacteria, the washing columns for effective removal of sample background and non-specific binding NFs, and the TMB column for colorimetric determination of target bacteria. The color change of TMB from colorless to blue was finally analyzed using the smartphone APP to quantitatively determine the target bacteria. This lab-on-a-disc platform could detect Salmonella typhimurium from 5.6 × 10^(1) CFU/20 μL to 5.6 × 10^(5) CFU/20 μL in 1 h with a lower detection limit of 56 CFU/20 μL. The recovery of target bacteria in spiked chicken samples ranged from 97.5% to 101.8%. This portable platform integrating separation, labeling, washing, catalysis and detection onto a single disc is featured with automatic operation, fast reaction, and small size and has shown its potential for in-field detection of foodborne pathogens.
基金This work was supported by the State of Indiana and the Indiana Clinical and Translational Sciences Institute(PHS NCCR#TL1RR025759 and#RR025761).
文摘Background:It is increasingly clear that in addition to myelin disruption,axonal degeneration may also represent a key pathology in multiple sclerosis(MS).Hence,elucidating the mechanisms of axonal degeneration may not only enhance our understanding of the overall MS pathology,but also elucidate additional therapeutic targets.The objective of this study is assess the degree of axonal membrane disruption and its significance in motor deficits in EAE mice.Methods:Experimental Autoimmune Encephalomyelitis was induced in mice by subcutaneous injection of myelin oligodendrocyte glycoprotein/complete Freud’s adjuvant emulsion,followed by two intraperitoneal injections of pertussis toxin.Behavioral assessment was performed using a 5-point scale.Horseradish Peroxidase Exclusion test was used to quantify the disruption of axonal membrane.Polyethylene glycol was prepared as a 30%(w/v)solution in phosphate buffered saline and injected intraperitoneally.Results:We have found evidence of axonal membrane disruption in EAE mice when symptoms peak and to a lesser degree,in the pre-symptomatic stage of EAE mice.Furthermore,polyethylene glycol(PEG),a known membrane fusogen,significantly reduces axonal membrane disruption in EAE mice.Such PEG-mediated membrane repair was accompanied by significant amelioration of behavioral deficits,including a delay in the emergence of motor deficits,a delay of the emergence of peak symptom,and a reduction in the severity of peak symptom.Conclusions:The current study is the first indication that axonal membrane disruption may be an important part of the pathology in EAE mice and may underlies behavioral deficits.Our study also presents the initial observation that PEG may be a therapeutic agent that can repair axolemma,arrest axonal degeneration and reduce motor deficits in EAE mice.
