共查询到20条相似文献,搜索用时 15 毫秒
1.
In this research, the enhancement of electron-transfer activity of hemoglobin (Hb) in lauric acid film was investigated for
the first time. This type of composite film was made on a glassy carbon electrode by a casting method. Cyclic voltammetric
result of the modified electrode displays a well-defined redox peak, which was attributed to the direct electrochemical response
of Hb. Our results illustrate that Hb exchange electrons directly with electrode and exhibits the characteristics of peroxidase.
When we use this modified electrode as a biosensor, it gives excellent performance in the electrocatalytic reduction of hydrogen
peroxide (H2O2). The parameters such as pH and applied potential of the biosensor influencing in H2O2 detection were optimized carefully. Through the optimal conditions, the proposed biosensor shows the linear range for H2O2 determination was from 1×10−5 to 1.25×10−4 mol L−1 with a detection limit of 1×10−7 mol L−1. The biosensor retained more than 90% of the initial response after 14 d. 相似文献
2.
An electrochemical biosensor for determination of hydrogen peroxide (H2O2) was fabricated, based on the electrostatic immobilization of horseradish peroxidase (HRP) with one-dimensional gold nanowires
(Au NWs) and TiO2 nanoparticles (nano-TiO2) on a gold electrode. The nano-TiO2 can give a biocompatible microenvironment and compact film, and the Au NWs can provide fast electron transferring rate and
greatly add the amount of HRP molecules immobilized on the electrode surface. Au NWs were characterized by ultraviolet–visible
spectra and transmission electron microscope. The electrode modification process was probed by cyclic voltammetry and electrochemical
impedance spectroscopy. Chronoamperometry was used to study the electrochemical performance of the resulting biosensor. Under
optimal conditions, the linear range for the determination of H2O2 was from 2.3 × 10−6 to 2.4 × 10−3 M with a detection limit of 7.0 × 10−7 M (S/N = 3). Moreover, the proposed biosensor showed superior stability and high sensitivity. 相似文献
3.
A mediator-free amperometric hydrogen peroxide biosensor was prepared by immobilizing horseradish peroxidase (HRP) enzyme
on colloidal Au modified platinum (Pt) wire electrode, which was modified by poly 2,6-pyridinediamine (pPA). The modified
process was characterized by electrochemical impedance spectroscopy (EIS), and the electrochemical characteristics of the
biosensor were studied by cyclic voltammetry, linear sweep voltammetry and chronoamperometry. The biosensor displayed an excellent
electrocatalytical response to reduction of H2O2 without the aid of an electron mediator, the linear range was 4.2 × 10−7–1.5 × 10−3 mol/L (r = 0.9977), with a detection limit of 1.4 × 10−7 mol/L. Moreover, the performance and factors influencing the resulted biosensor were studied in detail. The studied biosensor
exhibited permselectivity, good stability and good fabrication reproducibility. 相似文献
4.
A convenient and effective way for fabricating amperometric hydrogen peroxide (H2O2) biosensor was designed in this paper. First, the polyaniline (PANI) nanofibers membrane with good conductance and high surface
area was electropolymerized on a gold electrode surface. Then, Pt nanoparticle (PtNP) was electrochemically deposited on the
PANI nanofibers membrane. Finally, the hybrid film of gold nanoparticle, chitosan, and horseradish peroxidase (HRP) was cast
onto the modified electrode to form a stable biofunctional film, which was also employed as a protective layer to PtNP. The
proposed biosensor exhibited a rapid response to H2O2 with the linear range from 7.0 × 10−6 to 1.4 × 10−2 M and a detection limit of 2.8 × 10−6 M (S/N = 3). The sensitivity of 558 μA mM−1 cm−2 was obtained. The Michaelis–Menten constant,
K\textM\textapp K_{\text{M}}^{\text{app}} value was 1.90 mM suggesting a high affinity. Moreover, it displayed a good reproducibility and long-term stability. 相似文献
5.
The report is on an electrochemical biosensor with remarkably improved sensitivity toward nitrite. In this strategy, positively
charged gold nanoparticle (PCNA) is used in combination with multiwall carbon nanotubes (MWCNT) by electrostatic adsorption
for fabricating PCNA/MWCNT films. Then hemoglobin (Hb) biocatalyst will easily be attached to the surface of the combination
films aforementioned. After that, the Hb/PCNA films are immobilized onto the Hb/PCNA/MWCNT films through layer-by-layer assembly
technique. The (Hb/PCNA)2/MWNT/GC electrode thus prepared exhibits enhanced electrocatalytic behavior to the reduction of nitrite at −0.10 V versus
SCE in 0.05 M H2SO4 solution. On condition of the low detecting potential and low pH, interference caused by direct electrochemical oxidation or oxidizable
substances can be prevented. Therefore, the modified electrode shows fast response time, very high sensitivity, good selectivity
and stability. The current response of the sensor increases linearly with nitrite concentration from a range of 3.6 × 10−6 to 3.0 × 10−3 M with a detection limit(S /N = 3) of 9.6 × 10−7 M. 相似文献
6.
Yanxia Xu Jiangong Liang Chengguo Hu Fang Wang Shengshui Hu Zhike He 《Journal of biological inorganic chemistry》2007,12(3):421-427
Direct electron transfer of hemoglobin modified with quantum dots (QDs) (CdS) has been performed at a normal graphite electrode.
The response current is linearly dependent on the scan rate, indicating the direct electrochemistry of hemoglobin in that
case is a surface-controlled electrode process. UV–vis spectra suggest that the conformation of hemoglobin modified with CdS
is little different from that of hemoglobin alone, and the conformation changes reversibly in the pH range 3.0–10.0. The hemoglobin
in a QD film can retain its bioactivity and the modified electrode can work as a hydrogen peroxide biosensor because of its
peroxidase-like activity. This biosensor shows an excellent response to the reduction of H2O2 without the aid of an electron mediator. The catalytic current shows a linear dependence on the concentration of H2O2 in the range 5 × 10−7–3 × 10−4 M with a detection limit of 6 × 10−8 M. The response shows Michaelis–Menten behavior at higher H2O2 concentrations and the apparent Michaelis–Menten constant is estimated to be 112 μM. 相似文献
7.
Cytochrome c was immobilized covalently onto nickel oxide nanoparticles/carboxylated multiwalled carbon nanotubes/polyaniline composite (NiO-NPs/cMWCNT/PANI) electrodeposited on gold (Au) electrode. An amperometric H2O2 biosensor was constructed by connecting this modified Au electrode along Ag/AgCl as reference and Pt wire as counter electrode to the galvanostat. The modified Au electrode was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and Fourier transform infra-red spectroscopy (FTIR). Cyclic voltammetric (CV) studies of the electrode at different stages demonstrated that the modified Au electrode had enhanced electrochemical oxidation of H2O2, which offered a number of attractive features to develop an amperometric biosensor based on split of H2O2. There was a good linear relationship between the current (mA) and H2O2 concentration in the range 3–700 μM. The sensor had a detection limit of 0.2 μM (S/N = 3) with a high sensitivity of 3.3 mA μM?1 cm?2. The sensor gave accurate and satisfactory results, when employed for determination of H2O2 in different fruit juices. 相似文献
8.
Serge Ostrovidov Patricia Franck Josette Capiaumont Brigitte Dousset Francine Belleville 《In vitro cellular & developmental biology. Animal》1998,34(3):259-264
Summary The effect of low concentrations of hydrogen peroxide (H2O2) (5 × 10−7−9.5 × 10−7
M) on cell growth and antibody production was investigated with murine hybridoma cells (Mark 3 and anti-hPL) in culture. Cell
growth, measured by flow cytometry with morphological parameters, was significantly stimulated by H2O2 (8 × 10−7
M) but H2O2 concentration of 7 × 10−6
M and above increased cell death. H2O2 stimulation of antibody production was nonsignificant. The metabolism of cells treated with 8 × 10−7 or 1 × 10−5
M H2O2 was similar to that of the control in terms of glucose and glutamine consumption, lactate and ammonia production, and amino
acid concentrations in the medium. The concentrations of lactate dehydrogenase, a marker of cell death, in test and control
cells were similar. However, concentrations of intracellular free radicals measured by flow cytometry with dihydrorhodamine
123 (DHR 123) and dichlorofluorescein diacetate (DCFH-DA) as fluorochromes were different. The reactive oxygen species content
of cells in 8 × 10−7
M H2O2 was similar to that of the controls, but there was a sudden, marked production of superoxide anions (detected with DHR 123)
and H2O2 or peroxides (detected with DCFH-DA) by cells incubated with 1 × 10−5
M H2O2 which increased with increasing H2O2 until cell death. 相似文献
9.
《Journal of biochemical and biophysical methods》2008,70(3):407-413
A novel hydrogen peroxide biosensor was fabricated for the determination of H2O2. The precursor film was first electropolymerized on the glassy carbon electrode with p-aminobenzene sulfonic acid (p-ABSA) by cyclic voltammetry (CV). Then thionine (Thi) was adsorbed to the film to form a composite membrane, which yielded an interface containing amine groups to assemble gold nanoparticles (nano-Au) layer for immobilization of horseradish peroxidase (HRP). The electrochemical characteristics of the biosensor were studied by CV and chronoamperometry. The factors influencing the performance of the resulting biosensor were studied in detail. The biosensor responded to H2O2 in the linear range from 2.6 × 10− 6 mol/L to 8.8 × 10− 3 mol/L with a detection limit of 6.4 × 10− 7 mol/L. Moreover, the studied biosensor exhibited good accuracy and high sensitivity. The proposed method was economical and efficient, making it potentially attractive for the application to real sample analysis. 相似文献
10.
An advanced electrochemical sensor for the detection of enrofloxacin (ENR) based on the use of a modified electrode containing cadmium sulfide (CdS) nanoparticles (NPs) is reported. The CdS NPs were synthesized and characterized and then coated onto the electrode to fabricate a modified electrode that exhibited a lower limit of detection of 9.5 × 10?8 mol·L?1. This detection limit compares with a traditional electrode that exhibited a concentration detection range of 1.0 × 10?2 to 1.0 × 10?7 mol·L?1. This modified electrode demonstrated good selectivity, reproducibility, response time (<40 s), lifetime (up to 12 wk), and pH range (3.3‐7.2) for the determination of ENR in real samples (eg, pig urine). 相似文献
11.
A new amperometric biosensor for the detection of sugars was prepared. A glassy carbon electrode was modified with Prussian
blue (PB) nanoparticles protected by chitosan (CS) and poly(diallyldimethylammonium chloride) (PDDA), and then gold nanoparticles
were assembled onto the electrode followed by the assembly of 4-mercaptophenylboronic acid (MPBA) onto the surface of gold
nanoparticles through a sulfur–Au bond to fabricate a self-assembled biosensor. The PB nanoparticles protected by CS and PDDA
were characterized using transmission electron microscopy and UV–vis absorption spectroscopy. The characterization of the
self-assembled electrode was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The pK
a values of the MPBA monolayer before and after combining with sugars were determined. The fabricated electrode exhibited excellent
performances for determining d(+)-glucose, d(+)-mannose, and d(−)-fructose on the basis of the change in i
p of the Fe(CN)63−/4− ion in the presence of sugars. 相似文献
12.
Jasna Hrenovic Tomislav Ivankovic Lavoslav Sekovanic Mirela Rozic 《Central European Journal of Biology》2008,3(2):143-148
The antibacterial effect of cationic surfactants against the pure culture of phosphate (P)-accumulating bacterium Acinetobacter junii was investigated. The estimated EC50 values of the N-dodecylpyridinium chloride (DPC) for growth inhibition was 1.4±0.5 × 10−6 mol L−1 and for the inhibition of the P-uptake rates 7.3±2.6 × 10−5 mol L−1. The estimated EC50 values of the N-cetylpyridinium chloride (CPC) for growth inhibition was 4.9±1.3 × 10−7 mol L−1 and for the inhibition of the P-uptake rates 7.7±2.9 × 10−6 mol L−1. This suggests the importance of controlling the amounts of cationic surfactants in influent of the wastewater treatment
systems in order to avoid the possible failure of the biological P removal from wastewaters. 相似文献
13.
A novel third-generation biosensor for hydrogen peroxide (H2O2) has been constructed based on horseradish peroxidase (HRP) immobilized by the sol–gel (SG) technology on carbon nanotube
(CNT)-modified electrode. CNT has good promotion effects on the direct electron transfer between HRP and the electrode surface
and the SG network provides a biocompatible microenvironment for enzyme. The immobilized HRP retained its bioelectrocatalytic
activity for the reduction of hydrogen peroxide and can respond to the change of concentration of H2O2 rapidly. The heterogeneous electron transfer rate constant was evaluated to be 2.8 ± 0.4 s−1. The amperometric response to H2O2 shows a linear relation in the range from 0.5 to 300 μmol l−1 and a detection limit of 0.1 μmol l−1 (S/N = 3). The K
Mapp value of HRP immobilized on the electrode surface was found to be 1.35 mmol l−1. The biosensor exhibited high sensitivity, rapid response and excellent long-term stability. 相似文献
14.
Y. H. Qin Jaime A. Teixeira da Silva J. H. Bi S. L. Zhang G. B. Hu 《Plant Growth Regulation》2011,65(1):183-193
By identifying antibiotics that had the least phytotoxic effects on explants during genetic transformation, we evaluated the
effect of various antibiotics on callus induction and morphogenesis from leaf explants and in vitro growth of Fragaria × ananassa Duch. cv. Toyonaka. Results showed that kanamycin (Kan) significantly inhibited callus induction, bud differentiation and
root morphogenesis while carbenicillin (Carb), cefotaxime (Cef) and an equal concentration of Cef and Carb up to 500 mg L−1 had no significant effects on callus induction and shoot growth. Kan, even at 2.5 mg L−1, significantly inhibited callus induction, shoot regeneration and root formation, while no shoots regenerated at concentrations
above 15 mg L−1. Rooting was completely inhibited in the presence of 50 mg L−1 Kan. Cef had negative effects on shoot regeneration from leaf explants and in vitro growth of strawberry. Compared to Cef,
Carb at ≤300 mg L−1 significantly promoted shoot and root organogenesis. However, an equal concentration of Carb plus Cef could alleviate the
negative effect of Cef on strawberry. Results from relative electrolyte leakage, root and antioxidant activities, O2·− production rate, H2O2, proline and MDA contents showed that Kan, Cef and Carb caused electrolyte leakage and triggered active enzymatic processes
and metabolism. This offers a possible mechanism for the inhibition or stimulation of strawberry growth caused by these antibiotics. 相似文献
15.
The harmful effects of surfactants to the environment are well known. We were interested in investigating their potential
toxicity in a pure culture of Acinetobacter junii, a phosphate (P)-accumulating bacterium. Results showed a high acute toxicity of sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium
bromide (HDTMA) against A. junii. The estimated EC50 values of the HDTMA for the inhibition of CFUs in the pure culture of A. junii was 3.27 ± 1.12 × 10−7 mol L−1 and for the inhibition of the P-uptake rates 2.47 ± 0.51 × 10−6 mol L−1. For SDS, estimated EC50 values for the inhibition of CFUs in the pure culture of A. junii was 5.00 ± 2.95 × 10−6 mol L−1 and for the inhibition of the P-uptake rates 3.33 ± 0.96 × 10−4 mol L−1. The obtained EC50 values in the standardised yeast toxicity test using Saccharomyces cerevisiae were 3.03 ± 0.38 × 10−4 and 4.33 ± 0.32 × 10−5 mol L−1 for SDS and HDTMA, respectively. These results emphasized the need to control concentrations of surfactants entering the
activated sludge system. The negative effects of these toxicants could greatly decrease populations of P-accumulating bacteria,
as well as eukaryotic organisms, inhabiting activated sludge systems, which in turn could result in the decrease of the system
efficiency. 相似文献
16.
Influence of initial cellulose concentration on the carbon flow distribution during batch fermentation by Clostridium thermocellum ATCC 27405 总被引:1,自引:0,他引:1
The objective of this research was to understand how carbon loading influences hydrogen (H2) synthesis and metabolic flow patterns in the thermophilic, cellulolytic bacterium, Clostridium thermocellum. C. thermocellum was cultivated in batch cultures with high (5 g L−1) and low (1 g L−1) initial concentrations of α-cellulose at 60°C. The growth rate of C. thermocellum was 22% lower (0.15 h−1) in cultures with low-cellulose concentration compared with cultures with high-cellulose concentrations. Although substrate
depletion coincided with the end of log-growth in low-cellulose cultures, the prime reason for growth arrest in high-cellulose
cultures was not identified. Ethanol, acetate, and formate were the major soluble end-products with concomitant release of
H2 and CO2 under both conditions. Lactate appeared during the late log phase in high-carbon cultures when pH dropped below 6.4 and became
the major end-product in stationary phase. During the exponential phase of cell growth, significantly higher yields for H2 and acetate (1.90 ± 0.14 and 1.11 ± 0.04 mol/mol glucose equivalent, respectively) were obtained from low-cellulose cultures
compared to those from high-cellulose cultures. The maximum specific rate of H2 production, 6.41 ± 0.13 mmol H2/g dry cell/h, obtained during the exponential phase from low-carbon cultures was about 37% higher than that obtained from
high-carbon cultures. 相似文献
17.
Kaige Liu Ruo Yuan Yaqin Chai Dianping Tang Haizhen An 《Bioprocess and biosystems engineering》2010,33(2):179-185
[AuCl4]− was initially deposited by electrochemical reduction on a glassy carbon electrode (GCE) to form porous nanogold layer, then
prussian blue (PB) was electrodeposited onto the as-prepared nanogold layer, and then secondary nanogold particles were fabricated
again on the PB surface by electrochemical reduction for the immobilization of anti-CEA antibodies. The presence of double-layer
porous gold nanoparticles enhanced the immobilized amount of biomolecules, and improved the sensitivity of the immunoassay.
PB, as a good redox probe, was facile to electrochemical analysis and measurement. Under optimal conditions, the developed
immunoassay exhibited dynamic range from 3.0 to 80.0 ng/mL with a detection limit of 0.9 ng/mL CEA (S/N = 3). Moreover, the
selectivity, reproducibility and stability of the immunosensor were acceptable. 相似文献
18.
An electrochemiluminescence (ECL) sensor based on reduced graphene oxide–CdTe quantum dots (RGO–CdTe QDs) composites for detecting copper ion (Cu2+) was proposed. The ECL behaviours of the RGO–CdTe QD modified electrode were investigated with H2O2 as the co‐reactant. Quantitative detection of Cu2+ was realized as Cu2+ could effectively quench the ECL signal of the RGO–CdTe QDs. A wide linear range of 1.00 × 10?14 to 1.00 × 10?4 M (R = 0.9953) was obtained under optimized conditions, and a detection limit (S/N = 3) was achieved of as low as 3.33 × 10?15 M. The proposed sensor also exhibited good stability and selectivity for the detection of copper ions. Finally, the analytical application of the proposed sensor was also evaluated using river water. 相似文献
19.
A novel amperometric hydrogen peroxide biosensor based on the immobilization of hemoglobin on the 2,6-pyridinedicarboxylic
acid (PDC) polymer, thionine and nano-Au was successfully fabricated. In this strategy, PDC polymer acted as the matrices
to covalently immobilize the thionine, and then hemoglobin was successfully adsorbed on the nano-Au which was electro-deposited
on to thionine modified electrode surface. The preparation process of modified electrode was characterized with electrochemical
impedance spectroscopy and atomic force microscope. The analytical performance of proposed biosensor toward H2O2 was investigated by cyclic voltammetry and chronoamperometry. The resulted biosensor exhibited fast amperometric response
(within 6 s) to H2O2, and linear range was from 9.1 μM to 5.0 mM with the detection limit of 2.6 μM (S/N = 3). The apparent Michaelis–Menten constant
(K
Mapp) was evaluated to be 3.2 mM. Furthermore, the resulted biosensor showed good stability and reproducibility. 相似文献
20.
Nina K. Iversen David J. McKenzie Hans Malte Tobias Wang 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2010,180(4):495-502
Most teleost fish reduce heart rate when exposed to acute hypoxia. This hypoxic bradycardia has been characterised for many
fish species, but it remains uncertain whether this reflex contributes to the maintenance of oxygen uptake in hypoxia. Here
we describe the effects of inhibiting the bradycardia on oxygen consumption (MO2), standard metabolic rate (SMR) and the critical oxygen partial pressure for regulation of SMR in hypoxia (Pcrit) in European
eels Anguilla anguilla (mean ± SEM mass 528 ± 36 g; n = 14). Eels were instrumented with a Transonic flow probe around the ventral aorta to measure cardiac output (Q) and heart rate (f
H). MO2 was then measured by intermittent closed respirometry during sequential exposure to various levels of increasing hypoxia,
to determine Pcrit. Each fish was studied before and after abolition of reflex bradycardia by intraperitoneal injection of
the muscarinic antagonist atropine (5 mg kg−1). In the untreated eels, f
H fell from 39.0 ± 4.3 min−1 in normoxia to 14.8 ± 5.2 min−1 at the deepest level of hypoxia (2 kPa), and this was associated with a decline in Q, from 7.5 ± 0.8 mL min−1 kg−1 to 3.3 ± 0.7 mL min−1 kg−1 in normoxia versus deepest hypoxia, respectively. Atropine had no effect on SMR, which was 16.0 ± 1.8 μmol O2 kg−1 min−1 in control versus 16.8 ± 0.8 μmol O2 kg−1 min−1 following treatment with atropine. Atropine also had no significant effect on normoxic f
H or Q in the eel, but completely abolished the bradycardia and associated decline in Q during progressive hypoxia. This pharmacological inhibition of the cardiac responses to hypoxia was, however, without affect
on Pcrit, which was 11.7 ± 1.3 versus 12.5 ± 1.5 kPa in control versus atropinised eels, respectively. These results indicate,
therefore, that reflex bradycardia does not contribute to maintenance of MO2 and regulation of SMR by the European eel in hypoxia. 相似文献