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1.
A chemiluminescent (CL) detection method has been developed for DNA hybridization. The assay relies on a sandwich-type DNA
hybridization in which gold nanoparticles modified with alkylthiol-capped oligonucleotide strands are used as probes to monitor
the presence of the specific target DNA. The , which is the dissolving product of the gold nanoparticles anchored on the DNA hybrids, serves as an analyte in the H2O2–luminol– CL reaction for the indirect measurement of the target DNA. The combination of the remarkable sensitivity of the CL analysis
with the large number of released from each DNA hybrid allows a detection limit at levels as low as 0.1 pM of the target DNA. Moreover, with a further
silver amplification step, the detection limit will be pushed down to the femtomolar domain.
相似文献
2.
Miyamoto A Nakamura K Kishikawa N Ohba Y Nakashima K Kuroda N 《Analytical and bioanalytical chemistry》2007,388(8):1809-1814
A method that combines sequential injection analysis (SIA), flow injection analysis and chemiluminescence (CL) detection was
developed for the quasi-simultaneous determination of antioxidative activities against superoxide anion and nitric oxide (NO). The antioxidative activity was expressed as the decrease in luminol CL intensity caused by the quenching
of or NO by an antioxidant. The SIA system consisted of two syringe pumps, two selection valves, two holding coils, an HPLC
pump to deliver luminol solution, and a CL detector. Operation of the syringe pumps and multiport valves was controlled automatically
using a personal computer with appropriate software. A hypoxanthine (HX)-xanthine oxidase (XOD) system was used for the generation
of , and (±)-(E)-4-methyl-2-[(E)-hydroxyimino]-5-nitro-6-methoxy-3-hexenamide (NOR1) was employed as NO donor agent. The repeatability of the method was
evaluated with 35.2 μg ml−1
L-ascorbic acid, and the relative standard deviations (RSD) of the antioxidative activities were less than 3.8%. The quasi-simultaneous
determination of the antioxidative activities in one sample was completed within 2.0 min. The antioxidative activities of
some antioxidants and commercially available supplements containing certain antioxidants were successfully determined using
this system. The proposed system is rapid and reproducible, and thus may be useful for the screening of functional foods,
supplements and pharmaceutical formulations that exhibit antioxidative activity.
Figure The system that utilizes a combination of SIA and FIA with CL for the quasi-simultaneous determination of antioxidative activity
against a NO and b
. SP1, 2: syringe pump, HC1, 2: holding coil, MV1, 2: multi-port valve, P: pump, D: chemiluminescence detector, I: integrator, M1, 2: mixing tee, NOR1: (±)-(E)-4-methyl-2-[(E)- hydroxyimino]-5-nitro-6-methoxy-3-hexenamide, HX: hypoxanthine, XOD: xanthine oxidase. 相似文献
3.
Webb A 《Analytical and bioanalytical chemistry》2007,388(3):525-528
Figure Schematic diagram of a typical arrangement used for hyphenating chemical microseparations (e.g. capillary HPLC, CE, or CEC)
with microcoil NMR detection 相似文献
4.
Bhagat PR Pandey AK Acharya R Natarajan V Rajurkar NS Reddy AV 《Analytical and bioanalytical chemistry》2008,391(3):1081-1089
A molecular iodine selective membrane has been used for preconcentration of I2 generated in situ by iodometric reaction of with excess I− in acidic medium (pH 1–2). This iodometric reaction amplifies the iodine content six times resulting in enhancement of analytical
response ranging from three times for molecular methods to six times for elemental methods. The chemical conditions of this
iodometric reaction were optimized for quantitative generation and subsequent sorption of I2 in the membrane samples (96 ± 3%). The homogeneous transparent membrane was prepared by immobilizing I2-complexing polyvinylpyrrolidone (PVP) in the plasticized cellulose triacetate matrix. Four different analytical methods were
examined for quantitative determination of in iodized salt samples by preconcentrating it as I2 in the membrane matrix. These methods were: (1) spectrophotometry of the PVP-I2 complex formed in the membrane matrix, (2) a radiotracer method using I− tagged with 131I radiotracer, (3) instrumental neutron activation analysis (INAA), and (4) energy-dispersive X-ray fluorescence (EDXRF) analysis.
The contents thus determined in the iodized salt samples by the membrane-based radiotracer method were compared with the total
iodine determined in salt samples by epithermal instrumental neutron activation analysis (EINAA). The membrane-based method
for iodate determination in salt samples has advantages over conventional analytical methods, for example preconcentration
and chemical amplification, and is free from interference from anions.
Figure A molecular iodine selective membrane was used for the quantitative preconcentration of I2 generated in situ by iodometric reaction of with excess Iaˆ’ in acidic medium, which amplifies iodine content six times 相似文献
5.
Determination of norfloxacin in human urine by capillary electrophoresis with electrochemiluminescence detection 总被引:3,自引:0,他引:3
A fast and sensitive approach that can be used to detect norfloxacin in human urine using capillary electrophoresis with end-column
electrochemiluminescence (ECL) detection of is described. The separation column was a 75-μm i.d. capillary. The running buffer was 15 mmol L−1 sodium phosphate (pH 8.2). The solution in the detection cell was 50 mmol L−1 sodium phosphate (pH 8.0) and 5 mmol L−1
The ECL intensity varied linearly with norfloxacin concentration from 0.05 to 10 μmol L−1. The detection limit (S/N=3) was 0.0048 μmol L−1, and the relative standard deviations of the ECL intensity and the migration time for eleven consecutive injections of 1.0 μmol L−1 norfloxacin (n=11) were 2.6% and 0.8%, respectively. The method was successfully applied to the determination of norfloxacin spiked in human
urine without sample pretreatment. The recoveries were 92.7–97.9%.
相似文献
6.
Ramanavicius A 《Analytical and bioanalytical chemistry》2007,387(5):1899-1906
An amperometric biosensor for the determination of creatine was developed. The carbon rod electrode surface was coated with
sarcosine oxidase (SOX) and creatine amidinohydrolase by cross-linking under glutaraldehyde vapour. The SOX from Arthrobacter sp. 1–1 N was purified and previously used for creation of a creatine biosensor. The natural SOX electron acceptor, oxygen,
was replaced by an redox mediating system, which allowed amperometric detection of an analytical signal at +400-mV potential. The response time
of the biosensor was less than 1 min. The biosensor showed a linear dependence of the signal vs. creatine concentration at
physiological creatine concentration levels. The optimal pH in 0.1 M tris(hydroxymethyl)aminomethane (Tris)–HCl buffer was
found to be at pH 8.0. The half-life of the biosensor was 8 days in 0.1 M Tris–HCl buffer (pH 8.0) at 20 °C.
Principal scheme of consecutively followed catalytic reactions used to design a biosensor for the determination of creatine 相似文献
7.
Lee JO So HM Jeon EK Chang H Won K Kim YH 《Analytical and bioanalytical chemistry》2008,390(4):1023-1032
Recent advances in nanotechnology have enabled the development of nanoscale sensors that outperform conventional biosensors.
This review summarizes the nanoscale biosensors that use aptamers as molecular recognition elements. The advantages of aptamers
over antibodies as sensors are highlighted. These advantages are especially apparent with electrical sensors such as electrochemical
sensors or those using field-effect transistors.
Figure Feeling proteins with aptamer-functionalized carbon nanotubes 相似文献
8.
9.
Melander C Andersson E Axelsson S Gorton L 《Analytical and bioanalytical chemistry》2007,387(7):2585-2593
A novel method for detection of reducing ends of sugars is proposed, based on the use of as the oxidant in combination with amperometric detection and flow injection analysis (FIA). The method is very sensitive,
giving values of <10 μM for the limit of detection for a series of mono- and oligosaccharides. Samples can be analysed every
30 s, and injection can be made fully automated, making it possible to perform on-line analysis of polysaccharide samples
subjected to hydrolysis. Three methylcelluloses (MC) of different qualities were hydrolysed with three different glucanases,
and the concentrations of reducing ends prior to, during and after hydrolysis were determined. Differences were observed between
the results obtained using different combinations of enzymes and MCs, which revealed different selectivities of the various
enzymes for the different substrates. One MC was also hydrolysed and analysed in real-time for three hours. The method proposed
is superior to many of the standard methods used today, which require manual labour and have a lower sensitivity.
Figure Set-up used for the instrumentation in the FIA system with automated injection. A pump delivers the reaction solution to the
autosampler, where the samples are injected; the sample and solution react in a temperature-controlled random coil and the
response is detected using an amperometric detection cell 相似文献
10.
11.
Cortina M Duran A Alegret S del Valle M 《Analytical and bioanalytical chemistry》2006,385(7):1186-1194
Intelligent and automatic systems based on arrays of non-specific-response chemical sensors were recently developed in our
laboratory. For multidetermination applications, the normal choice is an array of potentiometric sensors to generate the signal,
and an artificial neural network (ANN) correctly trained to obtain the calibration model. As a great amount of information
is required for the proper modelling, we proposed its automated generation by using the sequential injection analysis (SIA)
technique. First signals used were steady-state: the equilibrium signal after a step-change in concentration. We have now
adapted our procedures to record the transient response corresponding to a sample step. The novelty in this approach is therefore
the use of the dynamic components of the signal in order to better discriminate or differentiate a sample. In the developed
electronic tongue systems, detection is carried out by using a sensor array formed by five potentiometric sensors based on
PVC membranes. For the developed application we employed two different chloride-selective sensors, two nitrate-selective sensors
and one generic response sensor. As the amount of raw data (fivefold recordings corresponding to the five sensors) is excessive
for an ANN, some feature extraction step prior to the modelling was needed. In order to attain substantial data reduction
and noise filtering, the data obtained were fitted with orthonormal Legendre polynomials. In this case, a third-degree Legendre
polynomial was shown to be sufficient to fit the data. The coefficients of these polynomials were the input information fed
into the ANN used to model the concentrations of the determined species (Cl−, and ). Best results were obtained by using a backpropagation neural network trained with the Bayesian regularisation algorithm;
the net had a single hidden layer containing three neurons with the tansig transfer function. The results obtained from the time-dependent response were compared with those obtained from steady-state
conditions, showing the former superior performance. Finally, the method was applied for determining anions in synthetic samples
and real water samples, where a satisfactory comparison was also achieved.
相似文献
12.
A novel thiocyanate (SCN−)-selective PVC membrane electrode based on a zinc-phthalocyanine (ZnPc) complex as neutral carrier is described. The membrane electrode containing ZnPc with 5.1% (w/w) ionophore, 29.2% (w/w) PVC, and 65.7% (w/w) 2-nitrophenyl octyl ether (o-NPOE) as plasticizer displayed an anti-Hofmeister selectivity sequence , and exhibited near-Nernstian potential response to thiocyanate ranging from about 1.0×10−1 to 1.0×10−6 mol L−1 with a detection limit of 7.5×10−7 mol L−1 and a slope of 58.1±0.5 mV per decade in pH 3.0 phosphate buffer solution at 25 °C. This preferential response is believed to be associated with the unique coordination between the central metal of the carrier and thiocyanate.
相似文献
13.
Nanostructured electrochemical DNA biosensors for detection of the effect of berberine on DNA from cancer cells 总被引:2,自引:0,他引:2
Ovádeková R Jantová S Letasiová S Stepánek I Labuda J 《Analytical and bioanalytical chemistry》2006,386(7-8):2055-2062
Multi walled carbon nanotubes (MWNT) in dimethylformamide (DMF) or aqueous sodium dodecyl sulfate (SDS) solution, colloidal
gold nanoparticles (GNP) in phosphate buffer solution (PBS), and a GNP–MWNT mixture in aqueous SDS solution have been investigated
for chemical modification of a screen-printed carbon electrode used as the signal transducer of a dsDNA-based biosensor. Differential
pulse voltammetry of the DNA redox marker and the guanine moiety anodic oxidation and cyclic voltammetry with K3[Fe(CN)6] as indicator revealed substantial enhancement of the response of the biosensor, particularly when MWNT in SDS solution was
used. The biosensor was used in testing of berberine, an isoquinoline plant alkaloid with significant antimicrobial and anticancer
activity. Berberine had a very strong, concentration-dependent, effect on the structural stability of DNA from the human cancer
cells (U937 cells) whereas non-cancer cells were changed only when berberine concentrations were relatively high 75 and 50 μg
mL−1.
Figure Schematic illustration of preparation of the nanostructured films: (a) layer-to-layer coverage (DNA/nanomaterial/SPE); (b) mixed coverage (DNA-nanomaterial/SPE) 相似文献
14.
Ortner K Sivanandam VN Buchberger W Müller N 《Analytical and bioanalytical chemistry》2007,388(1):173-177
Enzymatically cleaved glycans from sub-milligram quantities of erythropoietin (EPO) and ovalbumin have been analyzed, without
further purification, by two-dimensional diffusion-ordered nuclear magnetic resonance spectroscopy. At NMR sample concentrations
below 50 μmol L−1 the major components of the oligosaccharide fractions could be distinguished by their anomeric proton chemical shift and
their size-dependent diffusion coefficients.
Figure
1H NMR diffusion decay curves of anomeric protons in the EPO glycan fraction 相似文献
15.
Ma X Zhu T Xu H Li G Zheng J Liu A Zhang J Du H 《Analytical and bioanalytical chemistry》2008,390(4):1133-1137
A chemical prototype sensor was constructed based on nanofiber-structured TiO2 and highly sensitive quartz resonators. The gas-sensing behavior of this new sensor to selected simulant warfare agents was
investigated at room temperature. Results showed rapid response and good reversibility of this sensor when used with high-purity
nitrogen. This provides a simple approach to preparation of materials needed as chemical sensors for selected organic volatiles
or warfare agents.
Figure Sensing behavior of TiO2 nanofiber sensor to chemical vapors 相似文献
16.
New far-visible absorbing anilino-cyanine dyes have been synthesised for future application as chromoionophores in integrated
waveguide absorbance optodes based on bulk optodes. The effect of the heterocycle, of the substitution of the heterocyclic
nitrogen and of the type of heptamethine central ring on the pK
a
values (4.3–8.2 in ethanol–water solutions and 9.5–11.0 in plasticised PVC membranes), on the spectroscopic characteristics
of the dye and on photostability is discussed. pH-selective bulk optodes have been formulated as a first approach to develop
ion-selective optodes, and sensitivity, repeatability, lifetime and response time have been determined. The dyes show good
analytical behaviour for use as chromoionophores for the development of ion-selective optodes. Reversible (80–87%), fast (tr90% = 0.94–2.28 min) and pH-sensitive membranes (slopes of 0.09–0.23 ΔAbs·pHdec–1, absorbance range 0.19–0.53) have been obtained. Moreover, they exhibit good spectroscopic features for employment with integrated
optochemical sensors: absorption maxima of the acidic species in plasticised PVC membranes matched those of 650–670-nm LEDs,
high molar absorption coefficients ( L mol–1 cm–1 and L mol−1 cm−1) and fluorescence.
Absorption spectra of the acidic and basic structures of one of the synthesised chromoionophores at different pKa values.
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
17.
Cordes DB Miller A Gamsey S Singaram B 《Analytical and bioanalytical chemistry》2007,387(8):2767-2773
The simultaneous use of several fluorescent reporter dyes in a multicomponent boronic acid-based glucose sensing system is
reported. In one application, two dyes with widely different emission wavelengths are used to report changes in glucose concentration.
A third glucose-insensitive dye was then added to act as a reference dye and provide for a ratiometric correction to the two
reporter dye signals. The inclusion of such a reference dye reduces errors arising from sources such as fluctuations in lamp
intensity and sample dilution.
The simultaneous use of multiple fluorescent reporter dyes 相似文献
18.
Surmeian A Diplasu C Groza A Ganciu M Belenguer P Tempez A Chapon P 《Analytical and bioanalytical chemistry》2007,388(8):1625-1629
A high-current pulsed hollow cathode discharge was used to study the role of atomic and ionic metastables involved in ionization
plasma processes. We observed the enhancement of the spectral emission lines of noble gas ions in the afterglow. A study of
the processes that involve atomic and ionic metastables is of great interest since it should lead to a better understanding
of and enhanced control over the ionization mechanisms crucial to analytical glow discharge mass spectrometry (GDMS) analysis.
Figure Time profile of Ti, Ti+, and Ne+ spectral lines 相似文献
19.
The influence of dielectric substrates on the Raman scattering activities of Ag overlayers has been investigated. Materials
with low refractive indices, such as SiO2, SiOx and AlF3, were found to provide suitable supporting platforms for Ag films to give strong surface-enhanced Raman scattering for dye
molecules when illuminated at 488 nm. This finding was then extended to tip-enhanced Raman scattering (TERS). Huge enhancements
of 70–80×, corresponding to net enhancements of >104, were observed for brilliant cresyl blue test analyte when Ag-coated tips made from or precoated with low refractive index
materials were applied. The yield of fabricated tips that significantly enhance the Raman signals was found to be close to
100%. These findings provide crucial steps towards the use of TERS as a robust technique for rapid chemical imaging with nanometer
spatial resolution.
Figure Silver-coated dielectric tips for tip-enhanced Raman scattering (TERS) are capable of more than 10,000-fold enhancement 相似文献
20.
Schaffer B Grogger W Kothleitner G Hofer F 《Analytical and bioanalytical chemistry》2008,390(6):1439-1445
In this work we show how energy-filtered imaging can be used to obtain spectrum images of electron energy-loss spectrometric
data. Focus is placed on improved energy resolution within these data sets. Using two multilayer samples (GaN/AlN and InP/InAs),
we demonstrate the advantages of spectrum-imaging and its extended mapping capabilities. Plasmon-ratio maps are used to quickly
create high-contrast material maps with high signal-to-noise ratio, ratio-contrast plots are used to gain optimum settings
for the ratio maps, and plasmon-position maps are used to map small shifts of the energy position of bulk plasmon peaks.
Figure Scheme of EELS SI and derived plasman-position map 相似文献