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1.
Bernini R De Nuccio E Brescia F Minardo A Zeni L Sarro PM Palumbo R Scarfi MR 《Analytical and bioanalytical chemistry》2006,386(5):1267-1272
This paper describes an innovative integrated micro flow cytometer that presents a new arrangement for the excitation/detection
system. The sample liquid, containing the fluorescent marked particles/cells under analysis, is hydrodynamically squeezed
into a narrow stream by two sheath flows so that the particles/cells flow individually through a detection region. The detection
of the particles/cells emitted fluorescence is carried out by using a collection fiber placed orthogonally to the flow. The
device is based on silicon hollow core antiresonant reflecting optical waveguides (ARROWs). ARROW geometry allows one to use
the same channel to guide both the sample stream and the fluorescence excitation light, leading to a simplification of the
optical configuration and to an increase of the signal-to-noise ratio. The integrated micro flow cytometer has been characterized
by using biological samples marked with standard fluorochromes. The experimental investigation confirms the success of the
proposed microdevice in the detection of cells.
An erratum to this article can be found at 相似文献
2.
Short oxidized multi-walled carbon nanotubes (CNT) were derivatized with fluorescein isothiocyanate (FITC). Capillary electrophoresis
coupled with laser-induced fluorescence (CE–LIF) was then used to separate and detect the fluorescently labeled carbon-nanotube
probes (CNTP) in multidrug-resistant cells (K562A) and the parent cells (K562S). Greater expression of P-glycoprotein in K562A
cells than in K562S cells was confirmed by use of anti-P-glycoprotein antibody and flow-cytometric analysis. Analyses of CNTP
in both cell lines using both CE–LIF and flow cytometry showed that CNTP could traverse the cellular membrane without being
pumped out by P-glycoprotein. The CNTP distributed in both cell lines was analyzed at the single cell level and the results
were compared with those from analysis of ten cells and of the lysate from bulk cells. The results revealed the CE–LIF method
could be used for quantitative analysis of CNT in single cells in studies of drug delivery and multidrug resistance.
相似文献
3.
4.
Emily O’Neill Danielle Harrington John Allison 《Analytical and bioanalytical chemistry》2009,393(8):2029-2038
Monitoring of cell cultures in microbioreactors is a crucial task in cell bioassays and toxicological tests. In this work
a novel tool based on a miniaturized sensor array fabricated using low-temperature cofired ceramics (LTCC) technology is presented.
The developed device is applied to the monitoring of cell-culture media change, detection of the growth of various species,
and in toxicological studies performed with the use of cells. Noninvasive monitoring performed with the LTCC microelectrode
array can be applied for future cell-engineering purposes.
Figure Microelectrode array for monitoring of cell cultures 相似文献
5.
Thin nanoporous alumina obtained by anodization of aluminum films offers promising advantages for application in fluorescence-based biological sensors including convenient preparation, increased density of binding sites, and improved collection efficiency of fluorescence. These advantages are illustrated in the detection of streptavidin using biotin covalently bound to the surface of alumina nanopores. Fluorescence intensity enhancement as high as 7 times is observed in nanopores in comparison to flat glass surface.
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6.
Lapainis T Scanlan C Rubakhin SS Sweedler JV 《Analytical and bioanalytical chemistry》2007,387(1):97-105
A laser-induced native fluorescence detection system optimized for analysis of indolamines and catecholamines by capillary
electrophoresis is described. A hollow-cathode metal vapor laser emitting at 224 nm is used for fluorescence excitation, and
the emitted fluorescence is spectrally distributed by a series of dichroic beam-splitters into three wavelength channels:
250–310 nm, 310–400 nm, and >400 nm. A separate photomultiplier tube is used for detection of the fluorescence in each of
the three wavelength ranges. The instrument provides more information than a single-channel system, without the complexity
associfated with a spectrograph/charge-coupled device-based detector. With this instrument, analytes can be separated and
identified not only on the basis of their electrophoretic migration time but also on the basis of their multichannel signature,
which consists of the ratios of relative fluorescence intensities detected in each wavelength channel. The 224-nm excitation
channel resulted in a detection limit of 40 nmol L−1 for dopamine. The utility of this instrument for single-cell analysis was demonstrated by the detection and identification
of the neurotransmitters in serotonergic LPeD1 and dopaminergic RPeD1 neurons, isolated from the central nervous system of
the well-established neurobiological model Lymnaea stagnalis. Not only can this system detect neurotransmitters in these individual neurons with S/N>50, but analyte identity is confirmed on the basis of spectral characteristics.
Lapainis and Scanlan contributed equally to this work. 相似文献
7.
Towards biochips using microstructured optical fiber sensors 总被引:2,自引:0,他引:2
Rindorf L Høiby PE Jensen JB Pedersen LH Bang O Geschke O 《Analytical and bioanalytical chemistry》2006,385(8):1370-1375
In this paper we present the first incorporation of a microstructured optical fiber (MOF) into biochip applications. A 16-mm-long
piece of MOF is incorporated into an optic-fluidic coupler chip, which is fabricated in PMMA polymer using a CO2 laser. The developed chip configuration allows the continuous control of liquid flow through the MOF and simultaneous optical
characterization. While integrated in the chip, the MOF is functionalized towards the capture of a specific single-stranded
DNA string by immobilizing a sensing layer on the microstructured internal surfaces of the fiber. The sensing layer contains
the DNA string complementary to the target DNA sequence and thus operates through the highly selective DNA hybridization process.
Optical detection of the captured DNA was carried out using the evanescent-wave-sensing principle. Owing to the small size
of the chip, the presented technique allows for analysis of sample volumes down to 300 nL and the fabrication of miniaturized
portable devices.
相似文献
8.
A novel quartz device has been designed to trap arsine and selenium hydride and subsequently to volatilize the collected analyte
and atomize it for atomic-absorption spectrometric detection. The device is actually the multiple microflame quartz-tube atomizer
(multiatomizer) with inlet arm modified to serve as the trap and to accommodate the oxygen-delivery capillary used to combust
hydrogen during the trapping step. The effect of relevant experimental conditions (trap temperature during trapping and hydrogen
flow rate and trap temperature during volatilization) on collection and volatilization efficiency was investigated. Under
the optimum conditions collection and volatilization efficiency for arsenic and selenium were 50 and 70%, respectively.
相似文献
9.
Laser-induced breakdown spectroscopy (LIBS) in liquids using a double-pulse Q-switched Nd:YAG laser system has provided reliable
results that give trace detection limits in water. Resonant laser excitation has been added to enhance detection sensitivity.
A primary laser pulse (at 532 nm), transmitted via an optical fiber, induces a cavitation bubble and shockwave at a target
immersed in a 10 mg l−1–100 mg l−1 indium (In) water suspension. The low-pressure rear of the shockwave induces bubble expansion and a resulting reduction in
cavity pressure as it extends away from the target. Shortly before the maximum diameter is expected, a secondary laser pulse
(also at 532 nm) is fed into the bubble in order to reduce quenching processes. The plasma field generated is then resonantly
excited by a fiber-guided dye laser beam to increase detection selectivity. The resulting resonance fluorescence emission
is optically detected and processed by an intensified optical multichannel analyzer system.
相似文献
10.
An X-ray fluorescence method (XRF) is presented that allowed low detection limits (at the 0.1–23 ng mL−1 level) to be obtained for Cr, Mn, Fe, Ni, Zn, Sr, Pb, Bi and Br in water. The samples were prepared using a thin layer method. Trace elements were determined via the calibration curve and standard addition. Absorption effects and inhomogenities in prepared samples were checked for using the emission–transmission method and internal standards, respectively. The results from the XRF method were compared with the results from the inductively coupled plasma atomic emission spectrometry method.
相似文献
11.
Posthuma-Trumpie GA Venema K van Berkel WJ Korf J 《Analytical and bioanalytical chemistry》2007,389(6):2029-2033
This report describes a versatile and robust microreactor for bioactive proteins physically immobilized on a polyether sulfone
filter. The potential of the reactor is illustrated with glucose oxidase immobilized on a filter with a cut-off value of 30 kDa.
A flow-injection system was used to deliver the reactants and the device was linked on-line to an electrochemical detector.
The microreactor was used for on-line preparation of apoglucose oxidase in strong acid and its subsequent reactivation with
flavin adenine dinucleotide. In addition we describe a miniaturized version of the microreactor used to assess several characteristics
of femtomole to attomole amounts of glucose oxidase. A low negative potential over the electrodes was used when ferrocene
was the mediator in combination with horseradish peroxidase, ensuring the absence of oxidation of electro-active compounds
in biological fluids. A low backpressure at very low flow rates is an advantage, which increases the sensitivity. A variety
of further applications of the microreactor are suggested.
Figure Preparation of apoGOx and restoration of enzyme activity using a soluton of FAD 相似文献
12.
We report a simple method that combines dialysis, as a purification method, with the multielement capability of ICP to determine
the titanium-to-transferrin mole ratio at physiological pH, under buffer conditions. The method, by means of which titanium
and transferrin are determined simultaneously, enabled us to assess the binding capacities of different titanocene complexes.
Figure Titanocene dichloride 相似文献
13.
Determination of antimicrobial residues and metabolites in the aquatic environment by liquid chromatography tandem mass spectrometry 总被引:2,自引:0,他引:2
Antimicrobials are used in large quantities in human and veterinary medicine. Their environmental occurrence is of particular
concern due to the potential spread and maintenance of bacterial resistance. After intake by the organisms, the unchanged
drug and its metabolized forms are excreted and enter wastewater treatment plants where they are mostly incompletely eliminated,
and are therefore eventually released into the aquatic environment. The reliable detection of several antimicrobials in different
environmental aqueous compartments is the result of great improvements achieved in analytical chemistry. This article provides
an overview of the more outstanding analytical methods based on liquid chromatography tandem mass spectrometry, developed
and applied to determine antimicrobial residues and metabolites present in surface, waste, and ground waters.
相似文献
14.
SPME in environmental analysis 总被引:1,自引:0,他引:1
Recent advances in the use of solid-phase microextraction (SPME) in environmental analysis, including fiber coatings, derivatization
techniques, and in-tube SPME, are reviewed in this article. Several calibration methods for SPME, including traditional calibration
methods, the equilibrium extraction method, the exhaustive extraction method, and several diffusion-based calibration methods,
are presented. Recent developed SPME devices for on-site sampling and several applications of SPME in environmental analysis
are also introduced.
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15.
Because variability exists within populations of cells, single-cell analysis has become increasingly important for probing
complex cellular environments. Capillary electrophoresis (CE) is an excellent technique for identifying and quantifying the
contents of single cells owing to its small volume requirements and fast, efficient separations with highly sensitive detection.
Recent progress in both whole-cell and subcellular sampling has allowed researchers to study cellular function in the areas
of neuroscience, oncology, enzymology, immunology, and gene expression.
相似文献
16.
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
17.
Sensor technology and its application in environmental analysis 总被引:1,自引:0,他引:1
Environmental analysis is one of the fundamental applications of chemical sensors. In this review we describe different sensor
systems for the gas and liquid phases that have been tested either with real-life samples or in the field during the last
five years. Most field sensors rely either on electrochemical or optical transducers. In the gas phase, systems have been
proposed for analysis of oxides of nitrogen, carbon, and sulfur in air, and volatile organic compounds. In the liquid phase,
most detection systems used for real-life samples detect heavy-metal ions or organic contamination, for example pesticides,
organic solvents and polycyclic aromatic hydrocarbons.
Figure Chemical sensors for real-life environmental applications
Dedicated to Professor Ulrich Nickel on the occasion of his 65th birthday. 相似文献
18.
Zhang Y Wu HL Xia AL Zhu SH Han QJ Yu RQ 《Analytical and bioanalytical chemistry》2006,386(6):1741-1748
In this study a new spectrofluorimetric method for the direct determination of metoprolol in human plasma is presented and
discussed. It is based on the use of fluorescence excitation–emission matrices (EEMs) and second-order calibration performed
with parallel factor analysis (PARAFAC) or alternating trilinear decomposition (ATLD). This methodology enables accurate and
reliable discrimination of the analyte signal, even in the presence of unknown and uncalibrated fluorescent component(s),
which is often referred to as the second-order advantage. No separation or sample pretreatment steps were required. Satisfactory
results were obtained. Metoprolol recoveries in plasma were determined as 87±2% and 90±4% with PARAFAC and ATLD, respectively.
All RSD values of intra- and interday assays were below 5%.
Figure A three-dimensional plot of EEMs for a plasma sample and metoprolol solution 相似文献
19.
The use of polymers in microchip fabrication affords new opportunities for the development of powerful, miniaturized separation
techniques. One method in particular, the use of phase-changing sacrificial layers, allows for simplified designs and many
additional features to the now standard fabrication of microchips. With the possibility of adding a third dimension to the
design of separation devices, various means of enhancing analysis now become possible. The application of phase-changing sacrificial
layers in microchip analysis systems is discussed, both in terms of current uses and future possibilities.
Figure Phase-changing sacrificial materials enable multilayer microfluidic device layouts 相似文献
20.
Balaguer A Salvador A Chisvert A Meliá M Herráez M Díez O 《Analytical and bioanalytical chemistry》2006,385(7):1225-1232
Disodium phenyldibenzimidazole tetrasulfonate (PDT) is a new organic UV filter with hydrophilic properties used in modern
sunscreen spray formulations. The aim of this work was to develop and validate an analytical method that can be used to study
skin absorption of PDT from sunscreens. Results obtained in vitro for human skin showed a low level of absorption. The proposed
in vitro method employs a diffusion cell. Sunscreen lotion was applied onto pretreated human skin, which was then placed in
the cell. PDT was collected in a receptor liquid, the surface of which was in contact with the skin. The solutions obtained
were diluted appropriately and analyzed by liquid chromatography without any interference. The analytical features of chromatographic
determination with fluorimetic detection were suited to this analytical problem, since this method gave a limit of detection
of 1 ng ml−1. Phenol red (PR) was used as a marker to check the skin integrity, and a sensitive method based on sequential injection on-line
solid-phase extraction coupled with spectrophotometric detection was developed for determining this marker in the receptor
liquid in order to screen the cells.
相似文献