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1.
On the basis of the isoelectric point of an enzyme and the doping principle of conducting polymers, choline oxidase was doped
in a polyaniline film to form a biosensor. The amperometric detection of choline is based on the oxidation of the H2O2 enzymatically produced on the choline biosensor. The response current of the biosensor as a function of temperature was determined
from 3 to 40°C. An apparent activation energy of 22.8 kJ·mol−1 was obtained. The biosensor had a wide linear response range from 5 × 10−7 to 1 × 10−4 M choline with a correlation coefficient of 0.9999 and a detection limit of 0.2 μM, and had a high sensitivity of 61.9 mA·M−1·cm−2 at 0.50 V and at pH 8.0. The apparent Michaelis constant and the optimum pH for the immobilized enzyme are 1.4 mM choline
and 8.4, respectively, which are very close to those of choline oxidase in solution. The effect of selected organic compounds
on the response of the choline biosensor was studied. 相似文献
2.
Acetylcholinesterase-based biosensors for quantification of carbofuran, carbaryl, methylparaoxon, and dichlorvos in 5% acetonitrile 总被引:1,自引:0,他引:1
Valdés-Ramírez G Cortina M Ramírez-Silva MT Marty JL 《Analytical and bioanalytical chemistry》2008,392(4):699-707
Amperometric acetylcholinesterase biosensors have been developed for quantification of the pesticides carbofuran, carbaryl,
methylparaoxon, and dichlorvos in phosphate buffer containing 5% acetonitrile. Three different biosensors were built using
three different acetylcholinesterase (AChE) enzymes—AChE from electric eel, and genetically engineered (B394) and wild-type
(B1) AChE from Drosophila melanogaster. Enzymes were immobilized on cobalt(II) phthalocyanine-modified electrodes by entrapment in a photocrosslinkable polymer
(PVA-AWP). Each biosensor was tested against the four pesticides. Good operational stability, immobilisation reproducibility,
and storage stability were obtained for each biosensor. The best detection limits were obtained with the B394 enzyme for dichlorvos
and methylparaoxon (9.6 × 10−11 and 2.7 × 10−9 mol L−1, respectively), the B1 enzyme for carbofuran (4.5 × 10−9 mol L−1), and both the B1 enzyme and the AChE from electric eel for carbaryl (1.6 × 10−7 mol L−1). Finally, the biosensors were used for the direct detection of the pesticides in spiked apple samples. 相似文献
3.
A simple and new reagentless phenolic compound biosensor was constructed with tyrosinase immobilized in the gelatine matrix
cross-linked with formaldehyde. The morphologies of gelatine and gelatine/tryosinase were characterized by SEM. The tyrosinase
retains its bioactivity when being immobilized by the gelatine film. Phenolic compounds were determined by the direct reduction
of biocatalytically liberated quinone at -0.1 V vs SCE. The process parameters for the fabrication of the enzyme electrode
were studied. Optimization of the experimental parameters has been performed with regard to pH, operating potential, temperature
and storage stability. This biosensor exhibits a fast amperometric response to phenolic compounds. The linear range for catechol,
phenol, and p-Cresol determination was from 5×10−8 to 1.4×10−4 M, 5×10−8 to 7.1×10−5 M, and 1×10−7 to 3.6×10−5 M, with a detection limit of 2.1×10−8 M, 1.5×10−8 M, and 7.1×10−8 M, respectively. The enzyme electrode retained ca.77% of its activity after 7 days of storage at 4°C in a dry state. The proposed
sensor presented good repeatability, evaluated in terms of relative standard deviation (R.S.D.=8.6%) for eight different biosensors
and was applied for determination in water sample. The recovery for the sample was from 99.0% to 99.8%. 相似文献
4.
Radoi A Compagnone D Batic M Klincar J Gorton L Palleschi G 《Analytical and bioanalytical chemistry》2007,387(3):1049-1058
Bulk screen-printed electrodes (bSPEs) modified with zirconium phosphate (ZrP) and Meldola blue (MB) and by electrochemical deposition of a Reineckate film
(bMBZrPRs-SPEs) have been constructed and used as NADH sensors. Cyclic voltammetric investigation of these bulk electrochemically
modified screen-printed electrodes revealed stable catalytic activity in oxidation of the reduced form of the coenzyme nicotinamide
adenine dinucleotide (NADH). Flow-injection analysis (FIA) coupled with amperometric detection confirmed the improved stability
of the bMBZrPRs-SPEs (10−4 mol L−1 NADH, %RSD = 4.2, n = 90, pH 7.0). Other conditions, for example applied working potential (+50 mV relative to Ag|AgCl), flow rate (0.30 mL min−1) and pH-dependence (range 4.0–10.0) were evaluated and optimized. A glycerol biosensor, prepared by immobilizing glycerol
dehydrogenase (GDH) on the working electrode area of a bMBZrPRs-SPE, was also assembled. The biosensor was most stable at pH 8.5 (%RSD = 5.6, n = 70, 0.25 mmol L−1 glycerol). The detection and quantification limits were 2.8 × 10−6 and 9.4 × 10−6 mol L−1, respectively, and the linear working range was between 1.0 × 10−5 and 1.0 × 10−4 mol L−1. To assess the effect of interferences, and recovery by the probe we analyzed samples taken during fermentation of chemically
defined grape juice medium and compared the results with those obtained by HPLC. 相似文献
5.
A mediator-free glucose biosensor, termed a “third-generation biosensor,” was fabricated by immobilizing glucose oxidase (GOD)
directly onto an oxidized boron-doped diamond (BDD) electrode. The surface of the oxidized BDD electrode possesses carboxyl
groups (as shown by Raman spectra) which covalently cross-link with GOD through glutaraldehyde. Glucose was determined in
the absence of a mediator used to transfer electrons between the electrode and enzyme. O2 has no effect on the electron transfer. The effects of experimental variables (applied potential, pH and cross-link time)
were investigated in order to optimize the analytical performance of the amperometric detection method. The resulting biosensor
exhibited fast amperometric response (less than 5 s) to glucose. The biosensor provided a linear response to glucose over
the range 6.67×10−5 to 2×10−3 mol/L, with a detection limit of 2.31×10−5 mol/L. The lifetime, reproducibility and measurement repeatability were evaluated and satisfactory results were obtained. 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.
Shafiquzzaman Siddiquee Nor Azah Yusof Abu Bakar Salleh Soon Guan Tan Fatimah Abu Bakar 《Journal of Solid State Electrochemistry》2012,16(1):273-282
Electrochemical DNA biosensor was successfully developed by depositing the ionic liquid (e.g., 1-ethyl-3-methylimidazolium
trifluoromethanesulfonate ([EMIM][Otf])), ZnO nanoparticles, and chitosan (CHIT) nanocomposite membrane on a modified gold
electrode (AuE). The electrochemical properties of the [EMIM][Otf]/ZnO/CHIT/AuE for detection of DNA hybridization were studied.
Under optimal conditions using cyclic voltammetry, the target DNA sequences could be detected in the concentration range of
1.0 × 10−18 to 1.82 × 10−4 mol L−1, and with the detection limit of 1.0 × 10−19 mol L−1. This DNA biosensor detection approaches provide a quick, sensitive, and convenient method to be used in the identification
of Trichoderma harzianum. 相似文献
8.
Mahmoud Labib Martin Hedström Magdy Amin Bo Mattiasson 《Analytical and bioanalytical chemistry》2010,397(3):1217-1224
A novel technique for monitoring of low molecular mass analytes using a flow-injection capacitive biosensor is presented.
The method is based on the ability of a small molecular mass analyte to displace a large analyte–carrier conjugate from the
binding sites of an immobilized biorecognition element with weak affinity to both compounds. A model study was performed on
glucose as the small molecular mass analyte. In the absence of glucose, binding of a glucose polymer or a glycoconjugate to
concanavalin A results in a capacitance decrease. Upon introduction of glucose, it displaces a part of the bound glucose polymer
or glycoconjugate leading to a partial restoration of capacitance. Experimental results show that the change in capacitance
depends linearly on glucose concentration within the range from 1.0 × 10−5 to 1.0 × 10−1 M, corresponding to 1.8 μg ml−1 to 18 mg ml−1 in a logarithmic plot, with a detection limit of 1.0 × 10−6 (0.18 μg ml−1) under optimized conditions. In addition, by modifying the molecular mass of the glucose polymer, amount of biorecognition
element, and buffer composition, we were able to tune the analyte-sensing range. The developed technique has the benefits
of expanded dynamic range, high sensitivity, and excellent reusability. 相似文献
9.
Caglar P Tuncel SA Malcik N Landers JP Ferrance JP 《Analytical and bioanalytical chemistry》2006,386(5):1303-1312
A newly designed glass-PDMS microchip-based sensor for use in the determination of Ca2+ ions has been developed, utilizing reflectance measurements from arsenazo III (1,8-dihydroxynaphthalene-3,6-disulfonic acid-2,7-bis[(azo-2)-phenyl
arsenic acid]) immobilized on the surface of polymer beads. The beads, produced from cross-linked poly(p-chloromethylstyrene) (PCMS), were covalently modified with polyethylenimine (PEI) to which the Arsenazo III could be adsorbed.
The maximum amount of Arsenazo III which could be immobilized onto the PEI-attached PCMS beads was found to be 373.71 mg g−1 polymer at pH 1. Once fabricated, the beads were utilized at the detection point of the microfluidic sensor device with a
fiber optic assembly for reflectance measurements. Samples were mobilized past the detection point in the sensor where they
interact with the immobilized dye. The sensor could be regenerated and re-used by rinsing with HCl solution. The pH, voltage,
linear range, and the effect of interfering ions were evaluated for Ca2+ determination using this microchip sensor. At the optimum potential, 0.8 kV, and pH 9.0, the linear range of the microchip
sensor was 3.57 × 10−5 – 5.71 × 10−4 M Ca2+, with a limit of detection (LOD) of 2.68 × 10−5 M. The microchip biosensor was then applied for clinical analysis of calcium ions in serum with good results.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
10.
A novel molecularly imprinted polymer solid-phase extraction (MISPE) with flow-injection chemiluminescence (CL) was developed
for the determination of pazufloxacin mesilate (PZFX). The molecularly imprinted polymer (MIP) was synthesized by using PZFX
as the imprinting molecule. A glass tube packed the particles of the MIP was employed as MISPE micro-column, which was connected
into the sampling loop of the eight-way injection valve for on-line selective preconcentration and extraction of PZFX. The
eluent of acetonitrile:acetic acid (9:1, v:v) was used as carrier for eluting the adsorbed PZFX to react with the mixture
of cerium(IV) and sodium sulfite in the flow cell to produce strong CL. The relative intensity of CL was linear to PZFX concentration
in the range from 2.5 × 10−9 to 2.5 × 10−7 g mL−1. The limit of detection was 7 × 10−10 g mL−1 (3 σ) and the relative standard deviation for 5 × 10−8 g mL−1of PZFX solution was 3.7% (n = 7). This method has been applied to the determination of PZFX in human urine. 相似文献
11.
Ai-Lin Liu Jia-Dong Wang Wei Chen Xing-Hua Xia Yuan-Zhong Chen Xin-Hua Lin 《Journal of Solid State Electrochemistry》2012,16(4):1343-1351
A simple, rapid, sensitive, and accurate method for simultaneous electrochemical determination of procaine and its metabolite
(p-aminobenzoic acid, PABA) for pharmaceutical quality control and pharmacokinetic research was developed using a graphite paste
electrode. The differential pulse voltammetric results revealed that procaine and p-aminobenzoic acid, respectively, showed well-defined anodic oxidation peaks on a carbon paste electrode with a current peak
separation of 155 mV at a scan rate of 100 mV s−1. This well separation of the current peaks for these two compounds in voltammetry enables us to simultaneously determine
them. Good linearity (r > 0.998) between oxidation peak current and concentration was obtained in the range of 5.0 × 10−7–5.0 × 10−5 M for procaine and 5.0 × 10−7–2.0 × 10−5 M for PABA in pH 4.50 acetate buffer solution. The detection limit for both analytes is 5 × 10−8 M (S/N = 3:1). The present voltammetric method has been successfully used to determine trace p-aminobenzoic acid in procaine hydrochloride injection and procaine in plasma with a linear relationship of current to its
concentration ranging from 1.0 × 10−6 to 5.0 × 10−5 M (correlation coefficient of 0.9981) with a low detection limit of 5.0 × 10−7 M (S/N = 3:1). This validated method is promising to the study of pharmacokinetics in Sprague–Dawley rat and rabbit plasma after
an intravenous administration of procaine hydrochloride injection. 相似文献
12.
A new H2O2 biosensor was fabricated on the basis of nanocomposite films of hemoglobin (Hb), silver nanoparticles (AgNPs), and multiwalled
carbon nanotubes (MWNTs)–chitosan (Chit) dispersed solution immobilized on glassy carbon electrode (GCE). The immobilized
Hb displayed a pair of well-defined and reversible redox peaks with a formal potential (E
θ′) of −22.5 mV in 0.1 M pH 7.0 phosphate buffer solution. The apparent heterogeneous electron transfer rate constants (k
s) in the Chit–MWNTs film was evaluated as 2.58 s−1 according to Laviron’s equation. The surface concentration (Γ*) of the electroactive Hb in the Chit–MWNTs film was estimated to be (2.48 ± 0.25) × 10−9 mol cm−2. Meanwhile, the Chit–MWNTs/Hb/AgNPs/GCE demonstrated excellently electrocatalytical ability to H2O2. Its apparent Michaelis–Menten constant (K
Mapp) for H2O2 was 0.0032 mM, showing a good affinity. Under optimal conditions, the biosensors could be used for the determination of H2O2 ranging from 6.25 × 10−6 to 9.30 × 10−5 mol L−1 with a detection limit of 3.47 × 10−7 mol L−1 (S/N = 3). Furthermore, the biosensor possessed rapid response to H2O2 and good stability, selectivity, and reproducibility. 相似文献
13.
The unmediated choline sensor based on layered double hydroxides in hydrogen peroxide detection mode
ShouNian Ding Dan Shan WenJuan Yao HuaiGuo Xue YueMing Sun Serge Cosnier 《中国科学B辑(英文版)》2009,52(12):2281-2286
In this work, we have developed a novel choline biosensor on the basis of immobilization of choline oxidase (ChOx) by the attractive materials layered double hydroxides (LDHs). Amperometric detection of choline was evaluated by holding
the modified electrode at 0.5 V (vs. SCE). Due to the special properties of LDHs ([Zn3-Al-Cl]), such as chemical inertness, high porosity, and swelling property, the [Zn3-Al-Cl]/ChOx modified electrode exhibited an enhanced analytical performance. The biosensor provided a linear response to choline over
a concentration range from 3.7 × 10−6 to 6.3 × 10−4 M with a low detection limit of 3 × 10−7 M based on S/N=3. The apparent Michaelis-Menten constant was calculated to be 1.38 mM. In addition, the interaction between
ChOx and LDHs has also been investigated using FT-IR spectroscopy. 相似文献
14.
Limbut W Hedström M Thavarungkul P Kanatharana P Mattiasson B 《Analytical and bioanalytical chemistry》2007,389(2):517-525
A capacitive biosensor for the detection of bacterial endotoxin has been developed. Endotoxin-neutralizing protein derived
from American horseshoe crab was immobilized to a self-assembled thiol layer on a biosensor transducer (Au). Upon injection
of a sample containing endotoxin, a decrease in the observed capacitive signal was registered. Endotoxin could be determined
under optimum conditions with a detection limit of 1.0 × 10−13 M and linearity ranging from 1.0 × 10−13 to 1.0 × 10−10 M. Good agreement was achieved when applying endotoxin preparations purified from an Escherichia coli cultivation to the capacitive biosensor system, utilizing the conventional method for quantitative endotoxin determination,
the Limulus amebocyte lysate test as a reference. The capacitive biosensor method was statistically tested with the Wilcoxon signed rank test, which proved
the system is acceptable for the quantitative analysis of bacterial endotoxin (P < 0.05).
Figure The flow-injection capacitive biosensor system and the capacitive properties of the transducer surface, where CSAM is the capacitance change of the self-assembled thiol monolayer, CP is the capacitance change of the protein layer, Ca is the capacitance change of the analyte layer and CTotal is the total capacitance change measured at the working electrode/solution interface (modified from Limbut et al., 2006.
Biosens Bioelectron 22: 233-240) 相似文献
15.
Polymerization of (O-tolidine), as ring substituted derivative of benzidine was achieved electro-chemically in organic solution containing Bu4NBF4 (0.2 M) in dichloromethane as supporting electrolyte. The film was obtained by electropolymerization in solution containing
monomer in various ratio ((5 × 10−4)–(5 × 10−2) M). This polymer was characterized by cycling voltammetry, impedance measurement, UV-visible and FT-IR spectroscopy. 相似文献
16.
Miaoliang Huang Hongxun Yang Jihuai Wu Jianming Lin Zhang Lan Pingjiang Li Sancun Hao Peng Han Qiwei Jiang 《Journal of Sol-Gel Science and Technology》2007,42(1):65-70
Using poly(acrylonitrile-co-styrene) as polymer host, 1,2-propanediol carbonate, dimethyl carbonate and ethylene carbonate as mixture solvent, N-methyl-quinoline iodide and iodine as the source of I−/I3
−, a novel polymer gel electrolyte with ionic conductivity of 5.12 × 10−3 S· cm−1 at 25°C was prepared by sol-gel and hydrothermal methods. Based on the polymer gel electrolyte, a quasi-solid-state dye-sensitized
solar cell was fabricated. The solar cell possess better long-term stability and light-to-electrical energy conversion efficiency
of 4.04% under irradiation of 100 mW· cm−2. The influences of polymer host, solvent, N-methyl-quinoline iodide and temperature on ionic conductivity of the polymer gel electrolyte and the performance of the dye-sensitized
solar cell was discussed. 相似文献
17.
Jahan-Bakhsh Raoof Reza Ojani Mahsa Majidian Fereshteh Chekin 《Russian Journal of Electrochemistry》2010,46(12):1395-1401
The electrooxidation of D-penicillamine (D-PA) has been studied in the presence of potassium iodide in various buffered aqueous solutions (4.00 ≤ pH ≤ 9.00) at the
surface of glassy carbon electrode using cyclic voltammetry, differential pulse voltammetry and chronoamperometry. It has
been found that under optimum pH (pH 5.00) in cyclic voltammetry, the electrooxidation of D-PA in the presence of potassium iodide as a homogeneous mediator occurred at a potential about 220 mV less positive than
that in absence of potassium iodide at the surface of glassy carbon electrode. The homogeneous electrocatalytic oxidation
current wave of D-penicillamine was linearly dependent on the D-PA concentration and a linear calibration curve was obtained in the ranges 3.0 × 10−5−1.5 × 10−3 M and 9.0 × 10−6−1.2 × 10−4 M of D-PA with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods, respectively. The detection limits (2σ)
were determined as 3.0 × 10−5 and 3.5 × 10−6 M with CV and DPV, respectively. This method was also used for voltammetric determination of D-PA in pharmaceutical preparation by standard addition method. 相似文献
18.
A nitric oxide biosensor based on the photovoltaic effect of nano titanium dioxide on hemoglobin was fabricated with high
sensitivity, selectivity, as well as stability. The linear detection concentration range was 5.0 × 10−6–4.0 × 10−4 M. The detection limit was 1.0 × 10−6 M with a sensitivity of 8 nA/μM. The possible coexisting compounds would not interfere with the nitric oxide detection.
The article is published in the original. 相似文献
19.
Jiawei Zhang Xiaobin Huang Hao Wei Jianwei Fu Yawen Huang Xiaozhen Tang 《Journal of Solid State Electrochemistry》2012,16(1):101-107
Solid composite polymer electrolytes consisting of polyethylene oxide (PEO), LiClO4, and porous inorganic–organic hybrid poly (cyclotriphosphazene-co-4, 4′-sulfonyldiphenol) (PZS) nanotubes were prepared using the solvent casting method. Differential scanning calorimetry
and scanning electron microscopy were used to determine the characteristics of the composite polymer electrolytes. The ionic
conductivity, lithium ion transference number, and electrochemical stability window can be enhanced after the addition of
PZS nanotubes. The electrochemical impedance showed that the conductivity was improved significantly. Maximum ionic conductivity
values of 1.5 × 10−5 S cm−1 at ambient temperature and 7.8 × 10−4 S cm−1 at 80 °C were obtained with 10 wt.% content of PZS nanotubes, and the lithium ion transference number was 0.35. The good
electrochemical properties of the solid-state composite polymer electrolytes suggested that the porous inorganic–organic hybrid
polyphosphazene nanotubes had a promising use as fillers in SPEs and the PEO10–LiClO4–PZS nanotube solid composite polymer electrolyte might be used as a candidate material for lithium polymer batteries. 相似文献
20.
Lawuyi B Chen H Afkhami F Kulamarva A Prakash S 《Applied biochemistry and biotechnology》2007,142(1):71-80
This article demonstrates the potential of encapsulated, engineered Lactococcus lactis as a vehicle for the oral delivery of therapeutic proteins. Using alginate-poly-l-lysine-alginate membrane-encapsulated L. lactis engineered to secrete the reporter protein Staphylococcal aureus nuclease, we show comparable viability and protein secretion between free and immobilized cells. After 12 h, microcapsules
with a cell density of 4.8 × 105 colony forming unit (CFU) ml−1 grew to 2.2 × 108 CFU ml−1 and released 0.24 arbitrary unit (AU) ml−1 of nuclease, producing similar results as free cells, which grew from 3.4 × 105 to 1.9 × 108 CFU ml−1 and secreted 0.21 AU ml−1 of nuclease. Moreover, encapsulated cells at a density of 4.4 × 107 CFU ml−1 grew to 2.2 × 1010 CFU ml−1 in 12 h and secreted 15.3 AU ml−1 of nuclease although 3.1 × 107 CFU ml−1 of free cells reached only 2.3 × 109 CFU ml−1 and released 5.6 AU ml−1 of nuclease. We also show the sustained stability of the microcapsules during storage at 4°C over 8 weeks. 相似文献