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1.
The fabrication and electrochemical characteristics of a penicillamine (PCA) self-assembled monolayer modified gold electrode
were investigated. The electrode can enhance the electrochemical response of uric acid (UA), and the electrochemical reaction
of UA on the PCA electrode has been studied by cyclic voltammetry and differential pulse voltammetry. Some electrochemical
parameters, such as diffusion coefficient, standard rate constant, electron transfer coefficient and proton transfer number
have been determined for the electrochemical behavior on the PCA self-assembled monolayer electrode. The electrode reaction
of UA is an irreversible process, which is controlled by the diffusion of UA with two electrons and two protons transfer at
the PCA/Au electrode. In phosphate buffer (pH 5.0), the peak current is proportional to the concentration of UA in the range
of 6.0 × 10−5–7.0 × 10−4 mol L−1 and 2.0 × 10−5–7.0 × 10−4 mol L−1 for the cyclic voltammetry and differential pulse voltammetry methods with the detection limits of 5.0 × 10−6 and 3.0 × 10−6 mol L−1, respectively. The method can be applied to determine UA concentration in real samples. 相似文献
2.
A mercaptoacetic acid (MAA)-modified cadmium sulfide (CdS) nanoparticle was synthesized in aqueous solution and used as an
oligonucleotide label for the electrochemical detection of nopaline synthase (NOS) terminator gene sequence. The carboxyl
groups on the surface of the CdS nanoparticle can be easily covalently linked with NH2-modified NOS oligonucleotide probe sequences. The target ssDNA sequence was fixed onto the electrode surface by covalently
linking to a mercaptoethanol self-assembled gold electrode, and the DNA hybridization of target ssDNA with probe ssDNA was
accomplished on the electrode surface. The CdS nanoparticles anchored on the hybrids were dissolved in the solution by the
oxidation with HNO3 and further detected by a sensitive differential pulse anodic stripping voltammetric method. The detection results can be
used for monitoring the hybridization, and the NOS target sequence was satisfactorily detected in the approximate range from
8.0 × 10−12 to 4.0 × 10−9 mol L−1 with a detection limit of 2.75 × 10−12 mol L−1 (3σ). The established method extended the nanoparticle-labeled electrochemical DNA analysis to genetically modified organisms
(GMOs) specific sequence samples with higher sensitivity and selectivity. 相似文献
3.
A self-assembled electrode with a meso-2,3-dimercaptosuccinic acid (DMSA) monolayer has been characterized by electrochemical
quartz crystal microbalance and complex impedance analysis, surface enhanced Raman spectroscopy and cyclic voltammetry. The
self-assembled electrode was used for the simultaneous electrochemical detection of epinephrine (EP) and uric acid (UA) in
phosphate buffer of pH 7.7. The simultaneous oxidation of EP and UA was performed by cyclic voltammetry (CV) and differential
pulse voltammetry (DPV), and the signals for each method were well separated with a potential difference of over 330 mV and
without interference by each other. The detection limit of EP is 5.4 × 10−8 mol L−1 by CV and 5.3 × 10−8 mol L−1 by DPV and that of UA is 8.4 × 10−8 mol L−1 by CV and 4.2 × 10−8 mol L−1 by DPV. The DMSA self-assembled electrode can be applied to the simultaneous determination of EP and UA. 相似文献
4.
L. M. Doubova 《Russian Journal of Electrochemistry》2010,46(4):450-460
The kinetics of Ru[(NH3)6]3+ reduction in 1 M NaNO3 solution at Ag(210) and Ag(111) singlecrystal electrodes modified by n-decanthiol monolayer is studied by electrochemical impedance spectroscopy and cyclic voltammetry. By using these two methods,
standard rate constants of the redox reaction involving Ru[(NH3)6]3+/2+ redox couple in the absence and in the presence of the n-decanthiol film were estimated. The equivalent circuit describing the experimental data in the presence of the self-assembled
organic monolayer and in the absence of redox reaction is an electrical circuit comprising a large resistance (∼106 Ω) connected in parallel with a capacitance (∼10−8 F). Analysis of kinetic data and extrapolation of Tafel lines resulted in the determination of the rate constant at unmodified
Ag-electrode, which is characteristic of very fast heterogeneous electron transfer. The calculated rate constants for n-decanthiol-modified silver singlecrystal faces (210) and (111) in 1 M NaNO3 solution (pH 6.3) equal 4.63 × 10−5 and 3.05 × 10−5 cm/s, respectively. The results are compared with the data at hand reported by different authors for gold electrodes in indifferent
electrolyte solution in the absence and in the presence of self-assembled monolayer. 相似文献
5.
Fluphenazine, an important tranquilizer, was found to undergo effective accumulation on dodecanethiol (DDT) self-assembled
monolayer modified gold electrode (i.e. DDT/Au) and generated two anodic peaks at about 0.7 and 0.79 V (vs. SCE) in 0.05 M
Na2B4O7 (pH = 9.3) buffer solution. Sensitive and quantitative measurement of fluphenazine based on the former anodic peak was established
under optimum conditions. The peak current was linear to fluphenazine concentration in the range from 5 × 10−7 to 5 × 10−5 M, with a detection limit of 5 × 10−9 M. This method was successfully applied to the determination of fluphenazine in drug tablets and proved to be reliable compared
with UV spectrophotometry. In the presence of fluphenazine, the electrochemical oxidation of phenylephrine was catalyzed.
The DDT self-assembled monolayer was characterized by Fourier transform infrared spectroscopy, surface Raman spectroscopy,
X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, and electrochemical probing. 相似文献
6.
A novel hydrogen peroxide (H2O2) biosensor was developed by immobilizing hemoglobin on the gold colloid modified electrochemical pretreated glassy carbon
electrode (PGCE) via the bridging of an ethylenediamine monolayer. This biosensor was characterized by UV-vis reflection spectroscopy
(UV-vis), electrochemical impendence spectroscopy (EIS) and cyclic voltammetry (CV). The immobilized Hb exhibited excellent
electrocatalytic activity for hydrogen peroxide. The Michaelis–Menten constant (K
m) was 3.6 mM. The currents were proportional to the H2O2 concentration from 2.6 × 10−7 to 7.0 × 10−3 M, and the detection limit was as low as 1.0 × 10−7 M (S/N = 3). 相似文献
7.
《Analytical letters》2012,45(16):2559-2570
A sensitive electrochemical DNA biosensor based on a mixed monolayer structure self-assembled at nanoporous gold (NPG) electrode surface was prepared for Escherichia coli (E. coli) detection. The NPG was fabricated on gold electrode, onto which thiolated oligonucleotides (SH-DNA) and mercaptohexanol (MCH) were covalently linked forming a mixed self-assembled monolayer (SAM). The hybridization between the SH-DNA/MCH modified biosensor and E. coli DNA was monitored with differential pulse voltammetry measurement using methylene blue (MB) as the hybridization indicator. The biosensor can detect 1 × 10?12 M DNA target and 50 cfu/μL E. coli without any nucleic acid amplification steps. The detection limit was lowered to 50 cfu/mL after 5.0 h of incubation. 相似文献
8.
A new approach for a simple electrochemical detection of PAT gene fragment is described. Poly(2,6-pyridinedicarboxylic acid) (PDC) modified glassy carbon electrode (GCE) was prepared by potential scan electropolymerization in an aqueous solution. Mg2 ions were incorporated by immer-sion of the modified electrode in 0.5 mol/L aqueous solution of MgCl2 to complete the preparation of a generic "activated" electrode ready for binding the probe DNA. The ssDNA was linked to the conduct-ing polymer by forming a bidentate complex between the carboxyl groups on the polymer and the phosphate groups of DNA via Mg2 . DNA immobilization and hybridization were characterized with dif-ferential pulse voltammetry (DPV) by using methylene blue (MB) as indicator and electrochemical im-pedance spectroscopy (EIS). The EIS was of higher sensitivity for DNA detection as compared with voltammetric methods in our strategy. The electron transfer resistance (Ret) of the electrode surface in EIS in [Fe(CN)6]3-/4- solution increased after the immobilization of the DNA probe on the Mg/PDC/GCE electrode. The hybridization of the DNA probe with complementary DNA (cDNA) made Ret increase further. The difference between the Ret at ssDNA/Mg/PDC/GCE and that at hybridization DNA modified electrode (dsDNA/Mg/PDC/GCE) was applied to determine the specific sequence related to the target PAT gene with the dynamic range comprised between 1.0 × 10-9 and 1.0 × 10_5 mol/L. A detection limit of 3.4 × 10-10 mol/L of oligonucleotides can be estimated. 相似文献
9.
Yan Zhang Xiaoquan Lu Tianlu Liao Yina Cheng Xiuhui Liu Limin Zhang 《Journal of Solid State Electrochemistry》2007,11(9):1303-1312
The interaction of 5-[p-(mercaptopropyloxy)-phenyl]-10, 15, 20-triphenylporphyrin (H2MPTPP) and its metalloporphyrin (Co, Ni-MPTPP) with calf thymus deoxyribonucleic acid (DNA) has been studied on gold electrode
modified by thiol-porphyrin self-assembled monolayer (SAM). The mode and characteristics of their interaction with DNA have
been studied by cyclic voltammetry, scanning electrochemical microscope (SECM), and alternating current (AC) impedance. Some
electrochemical parameters have been determined, i.e., apparent heterogeneous reaction rate constant (k
eff from SECM and k
f from AC impedance) and the hindrance (B) of electrode. K3[Fe(CN)6] was used as probe to obtain some electrochemical information of electrode interface. SECM images obtained from interface
on SAM interacted with DNA showed very good resolution with different topography. Based on a comparison with the results from
experiments, a reasonable agreement between SECM and AC impedance can be obtained, which means a conjunction of them. It is
proposed to be electrostatic interaction of H2MPTPP, Co-MPTPP and Ni-MPTPP with DNA, and the attractive force between porphyrins and DNA follows the order Ni-MPTPP > Co-MPTPP > H2MPTPP. 相似文献
10.
The gold electrode self-assembled with the homocysteine monolayer (Hcy/Au) is demonstrated to catalyze the electrochemical response of dopamine (DA) by cyclic voltammetry. A pair of well-defined redox waves was obtained and the calculated standard rate constant (ks) is 2.1×10−2 cm/s at the self-assembled electrode. The reduction peak of DA can be used to determine the concentration of DA in presence of ascorbic acid (AA) owing to the Hcy/Au also catalyzing the electrochemical oxidation of AA. 相似文献
11.
M. H. Pournaghi-Azar F. Ahour M. S. Hejazi 《Analytical and bioanalytical chemistry》2010,397(8):3581-3587
Development of an electrochemical DNA biosensor for the direct detection and discrimination of double-stranded oligonucleotide
(dsDNA) corresponding to hepatitis C virus genotype 3a, without its denaturation, using a gold electrode is described. The
electrochemical DNA sensor relies on the modification of the gold electrode with 6-mercapto-1-hexanol and a self-assembled
monolayer of 14-mer peptide nucleic acid probe, related to the hepatitis C virus genotype 3a core/E1 region. The increase
of differential pulse voltammetric responses of methylene blue, upon hybridization of the self-assembled probe with the target
ds-DNA to form a triplex is the principle behind the detection and discrimination. Some hybridization experiments with non-complementary
oligonucleotides were carried out to assess whether the developed DNA sensor responds selectively to the ds-DNA target. Diagnostic
performance of the biosensor is described and the detection limit was found to be 1.8 × 10−12 M in phosphate buffer solution, pH 7.0. The relative standard deviation of measurements of 100 pM of target ds-DNA performed
with three independent probe-modified electrodes was 3.1%, indicating a remarkable reproducibility of the detection method. 相似文献
12.
Gold nanoparticles (nano Au)/titanium dioxide (TiO2) hollow microsphere membranes were prepared on the carbon paste electrode (CPE) for enhancing the sensitivity of DNA hybridization
detection. The immobilization of nano Au and TiO2 microsphere was investigated with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The hybridization
events were monitored with EIS using [Fe(CN)6]3−/4− as indicator. The sequence-specific DNA of the 35S promoter from cauliflower mosaic virus (CaMV35S) gene was detected with
this DNA electrochemical sensor. The dynamic detection range was from 1.0×10−12 to 1.0×10−8 mol/L DNA and a detection limit of 2.3×10−13 mol/L could be obtained. The polymerase chain reaction (PCR) amplification of the terminator of nopaline synthase (NOS) gene
from the real sample of a kind of transgenic soybean was also satisfactorily detected.
Supported by the National Natural Science Foundation of China (Grant Nos. 20635020 and 20375020), Doctoral Foundation of the
Ministry of Education of China (Grant No. 20060426001) and Natural Science Foundation of Qingdao City (Grant No. 04-2-JZP-8) 相似文献
13.
Liang Wang Jun Yue Bai Peng Fei Huang Hong Jing Wang Xiao Wei Wu Yu Qing Zhao 《Mikrochimica acta》2007,158(1-2):73-78
The electrochemical behaviors of uric acid (UA) at the penicillamine (Pen) self-assembled monolayers modified gold electrode
(Pen/Au) have been studied. The Pen/Au electrode is demonstrated to promote the electrochemical response of UA by cyclic voltammetry
(CV). The diffusion coefficient D of UA is 6.97 × 10−6 cm2 s−1. In differential pulse voltammetric (DPV) measurements, the Pen/Au electrode can separate the UA and ascorbic acid (AA) oxidation
potentials by about 120 mV and can be used for the selective determination of UA in the presence of AA. The detection limit
was 1 × 10−6 mol L−1. The modified electrode shows excellent sensitivity, good selectivity and antifouling properties. 相似文献
14.
A 4-Amino-2-mercaptopyrimidine self-assembled monolayer (AMP SAMs/Au) modified gold electrode was prepared. The electrochemical
behavior of acetaminophen on the AMP SAMs/Au was studied in Britton-Robinson (BR) buffer solution. Compared to a bare gold
electrode, the modified electrode exhibits a significant enhancement in the oxidation current response for acetaminophen.
The modified electrode was used for the determination of acetaminophen by square wave voltammetry. The oxidation current increased
linearly with the concentration of acetaminophen in the range of 2.0 × 10−6−4.0 × 10−3 M. The modified electrode made it possible to eliminate the interference of dopamine (DA), brucine, epinephrine (EP), and
norepinephrine (NE). The practical analytical utility was illustrated by the determination of acetaminophen in a commercially
available drug.
The text was submitted by the authors in English. 相似文献
15.
Carboxyl group-functionalized single-walled carbon nanotubes (SWNTs) and 2,6-pyridinedicarboxylic acid (PDC) were electropolymerized
by cyclic voltammetry on a glassy-carbon electrode (GCE) surface to form composite films (SWNTs/PDC). Zirconia was then electrodeposited
on the SWNTs/PDC/GCE from an aqueous electrolyte containing ZrOCl2 and KCl by cycling the potential between −1.1 V and +0.7 V at a scan rate of 20 mV s−1. DNA probes with a phosphate group at the 5′ end were easily immobilized on the zirconia thin films, because of the strong
affinity between zirconia and phosphate groups. The sensors were characterized by cyclic voltammetry (CV) and electrochemical
impedance spectroscopy (EIS). EIS was used for label-free detection of the target DNA by measuring the increase of the electron
transfer resistance (R
et) of the electrode surface after the hybridization of the probe DNA with the target DNA. The PAT gene fragment and polymerase
chain reaction (PCR) amplification of the NOS gene from transgenically modified beans were satisfactorily detected by use
of this DNA electrochemical sensor. The dynamic range of detection of the sensor for the PAT gene fragment was from 1.0 × 10−11 to 1.0 × 10−6 mol L−1 and the detection limit was 1.38 × 10−12 mol L−1. 相似文献
16.
Jun Yue Bai Liang Wang Hong Jing Wang Peng Fei Huang Yu Qing Zhao Sheng Di Fan 《Mikrochimica acta》2006,156(3-4):321-326
The electrochemical behavior of epinephrine (EP) at a mercaptoacetic acid (MAA) self-assembled monolayer modified gold electrode
was studied. The MAA/Au electrode is demonstrated to promote the electrochemical response of epinephrine by cyclic voltammetry.
The possible reaction mechanism is also discussed. The diffusion coefficient D of EP is 6.85 × 10−6 cm2 s−1. In 0.1 mol L−1 phosphate buffer (pH 7.20), a sensitive oxidation peak was observed at 0.177 V, and the peak current is proportional to the
concentration of EP in the range of 1.0 × 10−5–2.0 × 10−4 mol L−1 and 1.0 × 10−7–1.0 × 10−6 mol L−1. The detection limit is 5 × 10−8 mol L−1. The modified electrode is highly stable and can be applied to the determination of EP in practical injection samples. The
method is simple, quick, sensitive and accurate. 相似文献
17.
Kadirov M. K. Budnikova Yu. G. Kholin K. V. Valitov M. I. Krasnov S. A. Gryaznova T. V. Sinyashin O. G. 《Russian Chemical Bulletin》2010,59(2):466-468
The radical anion P4·− was detected and identified by the ESR method as a spin-adduct with nitrone during the electrochemical reduction of white
phosphorus in the presence of a spin trap, viz., α-phenyl-N-tert-butylnitrone, in a special electrolysis cell with a helical platinum working electrode in the potentiostatic mode. The character
of the behavior of P4·− and the spin trap during electrochemical reduction was monitored by cyclic voltammetry directly in the electrolysis cell,
and the spin-adduct formed was detected by ESR. 相似文献
18.
Mazloum-Ardakani M. Rajabi H. Mirjalili B. B. F. Beitollahi H. Akbari A. 《Journal of Solid State Electrochemistry》2010,14(12):2285-2292
In the present paper, the use of a novel carbon paste electrode modified by N,N′(2,3-dihydroxybenzylidene)-1,4-phenylene diamine (DHBPD) and TiO2 nanoparticles prepared by a simple and rapid method for the determination of hydrazine (HZ) was described. In the first part
of the work, cyclic voltammetry was used to investigate the redox properties of this modified electrode at various solution
pH values and at various scan rates. A linear segment was found with a slope value of about 48 mV/pH in the pH range 2.0–12.0.
The apparent charge transfer rate constant (k
s) and transfer coefficient (α) for electron transfer between DHBPD and TiO2 nanoparticles-modified carbon paste electrode were calculated. In the second part of the work, the mediated oxidation of
HZ at the modified electrode was described. It has been found that under optimum condition (pH 8.0) in cyclic voltammetry,
a high decrease in overpotential occurs for oxidation of HZ at the modified electrode. The values of electron transfer coefficients
(α) and diffusion coefficient (D) were calculated for HZ, using electrochemical approaches. Differential pulse voltammetry exhibited a linear dynamic range
from 1.0 × 10−8 to 4.0 × 10−6 M and a detection limit (3σ) of 9.15 nM for HZ. Finally, this method was used for the determination of HZ in water samples, using standard addition method. 相似文献
19.
Carboxylic group-functionalized carbon nanotubes (c-CNT) were modified on the surface of carbon paste electrode to obtain
a conducting precursor film. Positively charged poly-l-lysine (pLys) and negatively charged double-stranded DNA (dsDNA) were alternately adsorbed on the c-CNT-modified electrode,
forming (pLys/dsDNA)
n
layer-by-layer (LBL) films. Cyclic voltammetry and electrochemical impedance spectroscopy of the electroactive probe [Fe(CN)6]3−/4− could give the valuable dynamic information of multilayer films growth. The oxidative DNA damage induced by cadmium ion (Cd2+) in the LBL multilayer films was studied by differential pulse voltammetry (DPV) with methylene violet (MV) as the intercalation
redox probe. The electrochemical signals of MV on the multilayer films were effectively amplified via LBL technology. The
specific intercalation of MV into dsDNA base pairs and the amplified electrochemical response of MV, combined with the unique
feature of loading reversibility of MV in the DNA layer-by-layer films, made the difference in DPV response between the intact,
and damaged dsDNA films become pronounced. This biosensor exhibited that the (pLys/dsDNA)
n
films could be utilized for investigations of DNA damage. 相似文献
20.
Jahan Bakhsh Raoof Abolfazl Kiani Reza Ojani Roudabeh Valiollahi Sahar Rashid-Nadimi 《Journal of Solid State Electrochemistry》2010,14(7):1171-1176
Gold nanoparticles (GNs) could be efficiently immobilized on binary mixed self-assembled monolayers (SAMs) on a gold surface
composed of 1,6-hexanedithiol and 1-octanethiol (nano-Au/SAMs gold electrode). This GN chemically modified electrode was used
for electrochemical determination of ascorbic acid (AA) and dopamine (DA) in aqueous media. The result showed that the GN-modified
electrode could clearly resolve the oxidation peaks of AA and DA, with a peak-to-peak separation (∆E
p) of 110 mV enabling determination of AA and DA in the presence of each other. The linear analytical curves were obtained
in the ranges of 0.3–1.4 mM for AA and 0.2–1.2 mM for DA concentrations using differential pulse voltammetry. The detection
limits (3σ) were 9.0 × 10−5 M for AA and 9.0 × 10−5 M for DA. 相似文献