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1.
Pérez Pavón JL García Pinto C Guerrero Peña A Moreno Cordero B 《Analytical and bioanalytical chemistry》2008,391(2):599-607
In the present work we report the results obtained with a methodology based on direct coupling of a headspace generator to
a mass spectrometer for the identification of different types of petroleum crudes in polluted soils. With no prior treatment,
the samples are subjected to the headspace generation process and the volatiles generated are introduced directly into the
mass spectrometer, thereby obtaining a fingerprint of volatiles in the sample analysed. The mass spectrum corresponding to
the mass/charge ratios (m/z) contains the information related to the composition of the headspace and is used as the analytical signal for the characterization
of the samples. The signals obtained for the different samples were treated by chemometric techniques to obtain the desired
information. The main advantage of the proposed methodology is that no prior chromatographic separation and no sample manipulation
are required. The method is rapid, simple and, in view of the results, highly promising for the implementation of a new approach
for oil spill identification in soils.
Figure PCA score plots illustrate clear discrimination of types of crude oil in polluted soil samples (e.g. results are shown for
vertisol) 相似文献
2.
Sabine Borgmann 《Analytical and bioanalytical chemistry》2009,394(1):95-105
Reactive oxygen species (ROS) and reactive nitrogen species (RNS) play a crucial role in chemical signaling processes of biological
cells. Electrochemistry is one of the rare methods able to directly detect these species. ROS and RNS can be monitored in
the local microenvironment of cells in real time at the site where the actual signaling takes place. This review presents
recent advances made with amperometric electrochemical techniques. Existing challenges for the quantification of ROS and RNS
in biological systems are discussed to promote the development of innovative and reliable cell-based assays.
Figure Reactive oxygen and nitrogen species (ROS & RNS) are produced biological cells. An amperometric sensor is placed in close
proximity. The recorded current I is used to determine fluxes of certain species.
相似文献
Sabine BorgmannEmail: |
3.
A method has been developed for rapidly separating and detecting strychnine and brucine using a poly(dimethysiloxane) (PDMS)
microchip and electrochemical (EC) detection. PDMS microchannels dynamically modified by Brij35 are shown to be more efficient
than native ones. The two analytes are well separated within 90 s in 70 mmol/L acetate buffer (pH 5.5) containing 0.01% (v/v)
Brij35. Detection limits were found to be 1.0 μmol/L for strychnine and 0.2 μmol/L for brucine at S/N=3. The method was used
to determine trace strychnine and brucine in rat serum, and the results obtained correlate well with those obtained via high-performance
liquid chromatography (HPLC).
相似文献
4.
Stephanie L. Daniels Johnpeter N. Ngunjiri Jayne C. Garno 《Analytical and bioanalytical chemistry》2009,394(1):215-223
Individual ferritin molecules can be sensitively detected using magnetic sample modulation (MSM) combined with contact mode
atomic force microscopy (AFM). To generate an oscillating magnetic field, an alternating current (AC) was applied to a solenoid
placed within the base of the AFM sample stage. When a modulated electromagnetic field is applied to samples, ferromagnetic
and paramagnetic nanomaterials are induced to vibrate. The flux of the AC electromagnetic field causes the ferritin samples
to vibrate with corresponding rhythm and periodicity of the applied field. This motion can be detected and mapped using contact
mode AFM with a soft, nonmagnetic cantilever. Changes in the phase and amplitude of the periodic motion of the sample are
sensed by the tip to selectively map vibrating magnetic nanomaterials. Particle lithography was used to create nanopatterned
test platforms of ferritin for MSM measurements. Regularly spaced structures of proteins provide precise reproducible dimensions
for multiple successive surface measurements at dimensions of tens of nanometers.
Figure Ring patterns of ferritin were used as nanoscale test platforms to characterize magnetic properties at the level of individual
proteins with AFM imaging
相似文献
Jayne C. GarnoEmail: |
5.
Masaya Murata Yukihiro Okamoto Yeon-Su Park Noritada Kaji Manabu Tokeshi Yoshinobu Baba 《Analytical and bioanalytical chemistry》2009,394(1):277-283
We investigated properties of cells affecting their optical trapping force and successfully established a novel cell separation
method based on the combined use of optical trapping force and microfluidics on a microchip. Our investigations reveal that
the morphology, size, light absorption, and refractive index of cells are important factors affecting their optical trapping
force. A sheath flow of sample solutions created in a microchip made sample cells flow in a narrow linear stream and an optical
trap created by a highly focused laser beam captured only target cells and altered their trajectory, resulting in high-efficiency
cell separation. An optimum balance between optical trapping force and sample flow rate was essential to achieve high cell
separation efficiency. Our investigations clearly indicate that the on-chip optical trapping method allows high-efficiency
cell separation without cumbersome and time-consuming cell pretreatments. In addition, our on-chip optical trapping method
requires small amounts of sample and may permit high-throughput cell separation and integration of other functions on microchips.
Figure Optical trapping in a microchannel allows high-efficiency separation of cells, e.g., dead and live HeLa cells
相似文献
Yukihiro OkamotoEmail: |
6.
Partition layer-modified substrates for reversible surface-enhanced Raman scattering detection of polycyclic aromatic hydrocarbons 总被引:1,自引:0,他引:1
Courtney L. Jones Kyle C. Bantz Christy L. Haynes 《Analytical and bioanalytical chemistry》2009,394(1):303-311
Herein, we present progress towards an analytical sensor for polycyclic aromatic hydrocarbons (PAHs) using surface-enhanced
Raman scattering (SERS) on partition layer-modified nanostructured substrates. Specifically, a 1-decanethiol monolayer has
been assembled on a silver film over nanospheres substrate to concentrate PAHs within the zone of SERS detection. Both anthracene
and pyrene were detected with limits of detection at 300 and 700 pM, respectively. The measured SERS spectra allowed for easy
distinction of the two PAH compounds, due to varying peak locations, and insight into the partitioning mechanism. Additionally,
exposure to a common environmental interferant, Suwannee River fulvic acid, did not impede the measurement of the PAHs, and
the sensor is reusable after a short exposure to 1-octanol. Finally, the utility of this sensing platform for PAH detection
was compared to that achievable for other classes of organic pollutants such as polychlorinated biphenyls and polybrominated
diphenyl ethers.
Figure SERS detection of polycyclic aromatic hydrocarbons facilitated via partition layer modified substrates.
相似文献
Christy L. HaynesEmail: |
7.
Environmental metabolomics is a growing and emerging sub-discipline of metabolomics. Studies with earthworms have progressed
from the initial stages of simple contact exposure tests to detailed studies of earthworm responses in soil. Over the past
decade, a variety of endogenous metabolites have been identified as potential biomarkers of contaminant exposure. Furthermore,
metabolomic methods have delineated responses from sub-lethal exposure of earthworms to polycyclic aromatic hydrocarbons and
metals in soil suggesting that environmental metabolomics may be used as a direct measure of contaminant bioavailability in
soil. Environmental metabolomics has the potential to fill knowledge gaps related to earthworm toxicity and contaminant bioavailability.
However, challenges with metabolite quantification and limited systems-level models of metabolic data require improvement
before detailed models of “normal” responses can be developed and used routinely in assessment of contaminated sites. Nonetheless,
environmental metabolomics is poised to improve our fundamental understanding of earthworm responses and toxicity to contaminants
in soil.
Figure Principal component analysis (PCA) scores plots of earthworm metabolic profiles measured by 1H NMR spectroscopy after exposure to sub-lethal concentrations of phenanthrene in soil.
相似文献
Myrna J. SimpsonEmail: |
8.
Christine Mousty 《Analytical and bioanalytical chemistry》2010,396(1):315-325
Two-dimensional layered inorganic solids, such as cationic clays and layered double hydroxides (LDHs), also defined as anionic
clays, have open structures which are favourable for interactions with enzymes and which intercalate redox mediators. This
review aims to show the interest in clays and LDHs as suitable host matrices likely to immobilize enzymes onto electrode surfaces
for biosensing applications. It is meant to provide an overview of the various types of electrochemical biosensors that have
been developed with these 2D layered materials, along with significant advances over the last several years. The different
biosensor configurations and their specific transduction procedures are discussed.
相似文献
9.
Hideki Kuramitz 《Analytical and bioanalytical chemistry》2009,394(1):61-69
This review provides a summary of recent works concerning electrochemical immunoassays using magnetic microbeads as a solid
phase. Recent research activity has led to innovative and powerful detection strategies that have been resulted in sensitive
electrochemical detection. Coupling of magnetic microbeads with highly sensitive electrochemical detection provides a useful
analytical method for environmental evaluation and clinical diagnostics, etc. The huge surface area and high dispersion capability
of magnetic microbeads strongly contributes towards the development of new sensitive, rapid, user-friendly, and miniaturized
electrochemical immunoassay systems. Moreover, the immunocomplexes formed on the magnetic microbead surface can be easily
detected without pretreatment steps such as preconcentration or purification, which are normally required for standard methods.
The discussion in this review is organized in two main subjects that include magnetic-microbead-based assays using enzyme
labels and nanoparticle tags.
Figure SEM image of Dynabeads M-280 (12% γ-Fe2O3 in polystyrene, diameter is 2.8 μm)
相似文献
Hideki KuramitzEmail: |
10.
A capillary-assembled microchip (CAs-CHIP), prepared by simply embedding square capillaries in a lattice polydimethylsiloxane
(PDMS) channel plate with the same channel dimensions as the outer dimensions of the square capillaries, has been used as
a diffusion-based pretreatment attachment in capillary electrophoresis (CE). Because the CAs-CHIPs employ square-section channels,
diffusion-based separation of small molecules from sample solutions containing proteins is possible by using the multilayer
flow formed in the square section channel. When a solution containing high-molecular-weight and low-molecular-weight species
makes contact with a buffer solution, the low-molecular-weight species, which have larger diffusion coefficients than the
high-molecular-weight species, can be collected in a buffer-solution phase. The collected solution containing the low-molecular-weight
species is introduced into the separation capillary to be analyzed by CE. This type of system can be used for CE analysis
in which pretreatment is required to remove proteins. In this work a fluorescently labeled protein and rhodamine-based molecules
were chosen as model species and a feasibility study was performed.
相似文献
11.
Wei Wang Shu-Hui Zhang Lin-Mei Li Zong-Li Wang Jie-Ke Cheng Wei-Hua Huang 《Analytical and bioanalytical chemistry》2009,394(1):17-32
Communication between cells by release of specific chemical messengers via exocytosis plays crucial roles in biological process.
Electrochemical detection based on ultramicroelectrodes (UMEs) has become one of the most powerful techniques in real-time
monitoring of an extremely small number of released molecules during very short time scales, owing to its intrinsic advantages
such as fast response, excellent sensitivity, and high spatiotemporal resolution. Great successes have been achieved in the
use of UME methods to obtain quantitative and kinetic information about released chemical messengers and to reveal the molecular
mechanism in vesicular exocytosis. In this paper, we review recent developments in monitoring exocytosis by use of UMEs-electrochemical-based
techniques including electrochemical detection using micrometer and nanometer-sized sensors, scanning electrochemical microscopy
(SECM), and UMEs implemented in lab-on-a-chip (LOC) microsystems. These advances are of great significance in obtaining a
better understanding of vesicular exocytosis and chemical communications between cells, and will facilitate developments in
many fields, including analytical chemistry, biological science, and medicine. Furthermore, future developments in electrochemical
probing of exocytosis are also proposed.
Figure In this paper, we review recent developments in monitoring the exocytosis by use of UMEs-electrochemical-based techniques
including electrochemical detection using micrometer and nanometer-sized sensors, Scanning Electrochemical Microscopy (SECM)
and UMEs implemented in lab-on-a-chip (LOC) microsystems. These advances are of great significance in obtaining a better understanding
of vesicular exocytosis and chemical communications between cells, and will facilitate developments in many fields including
analytical chemistry, biological science and medicine. Furthermore, future developments in electrochemical probing of exocytosis
are proposed.
相似文献
Wei-Hua HuangEmail: |
12.
Anti-lysozyme aptamers are found to preferentially bind to the edge of a tightly packed lysozyme pattern. Such edge-binding
is due to the better accessibility and flexibility of the edge lysozyme molecules. Kelvin probe force microscopy (KPFM) was
used to study the aptamer–lysozyme binding. Our results show that KPFM is capable of detecting the aptamer–protein binding
down to the 30 nm scale. The surface potential of the aptamer–lysozyme complex is approximately 12 mV lower than that of the
lysozyme. The surface potential images of the aptamer-bound lysozyme patterns have the characteristic shoulder steps around
the pattern edge, which is much wider than that of a clean lysozyme pattern. These results demonstrate the potentials of KPFM
as a label-free method for the detection of protein–DNA interactions.
Figure Aptamers preferentially bind on the edge of a protein pattern as revealed by Kelvin force microscopy.
相似文献
Yuguang CaiEmail: |
13.
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
14.
Heavy metal ions are highly toxic species which can cause long-term damage to biological systems. These species are known
to disrupt biological events at the cellular level, cause significant oxidative damage, and are carcinogens. The production
of simple, in-field detection methods that are highly sensitive for these cations is highly desirable in response to global
pollution. In that regard, bio-inspired colorimetric sensing systems have been developed to detect Hg2+ and Pb2+, and other cations, down to nmol L−1 concentrations. The benefits of these systems, which are reviewed herein, include cost-effective production, facile usage,
and a visual color change for the detection method. Such advantages are significant positive steps for heavy metal ion detection,
especially in regions where sophisticated laboratory studies are prohibited.
Figure Biological-based colorimetric detection of heavy metal cations. The materials on the left are independent Au nanoparticles
in solution, functionalized with heavy metal binding biomolecules, which, upon metal addition, aggregate to evolve a detectable
solution color change.
相似文献
Marc R. KnechtEmail: |
15.
Tuulia Hyötyläinen 《Analytical and bioanalytical chemistry》2009,394(3):743-758
Sample preparation before chromatographic separation is the most time-consuming and error-prone part of the analytical procedure.
Therefore, selecting and optimizing an appropriate sample preparation scheme is a key factor in the final success of the analysis,
and the judicious choice of an appropriate procedure greatly influences the reliability and accuracy of a given analysis.
The main objective of this review is to critically evaluate the applicability, disadvantages, and advantages of various sample
preparation techniques. Particular emphasis is placed on extraction techniques suitable for both liquid and solid samples.
Figure Miniaturised extraction techniques allow sensitive analysis of also small sample volumes. 相似文献
16.
Warunya Boonjob María Rosende Manuel Miró Víctor Cerdà 《Analytical and bioanalytical chemistry》2009,394(1):337-349
Two novel dynamic extraction approaches, the so-called sequential injection microcolumn extraction and sequential injection
stirred-flow chamber extraction, based on the implementation of a sample-containing container as an external extraction reactor
in a sequential injection network, are for the first time, optimized and critically appraised for fractionation assays. The
three steps of the original Community Bureau of Reference (BCR) sequential extraction scheme have been performed in both automated
dynamic fractionation systems to evaluate the extractability of Cr, Cu, Ni, Pb, and Zn in a standard reference material of
coal fly ash (NIST 1633b). In order to find the experimental conditions with the greatest influence on metal leachability
in dynamic BCR fractionation, a full-factorial design was applied, in which the solid sample weight (100–500 mg) and the extraction
flow rate (3.0–6.0 mL min−1) were selected as experimental factors. Identical cumulative extractabilities were found in both sequential injection (SI)-based
methods for most of assayed trace elements regardless of the extraction conditions selected, revealing that both dynamic fractionation
systems, as opposed to conventional steady-state BCR extraction, are not operationally defined within the selected range of
experimental conditions. Besides, the proposed automated SI assemblies offer a significant saving of operational time with
respect to classical BCR test, that is, 3.3 h versus 48 h, for complete fractionation with minimum analyst involvement.
Schematic illustration of automatic flow-based setups for dynamic fractionation of trace metals in fly ash
相似文献
Manuel MiróEmail: |
17.
The identification of ignitable liquid residues in fire debris is a key finding for determining the cause and origin of a
suspicious fire. However, the complex mixtures of organic compounds that comprise ignitable liquids are susceptible to microbiological
attack following collection of the sample. Biodegradation can result in selective removal of many of the compounds required
for identification of an ignitable liquid. Such degradation has been found to occur rapidly in substrates such as soil, rotting
wood, or other organic matter. Furthermore, fire debris evidence must often be stored for extended periods at room temperature
prior to analysis due to case backlogs and available evidence storage. Hence, extensive damage to ignitable liquid residues
by microbes poses a significant threat to subsequent laboratory work. In this work, the effects of microbial degradation of
ignitable liquids in soil have been evaluated as a function of time. Key findings include the loss of n-alkanes, particularly C9–C16, which showed the most dramatic decrease in gasoline as well as the petroleum distillates, while branched alkanes remained
unchanged. Monosubstituted benzenes also showed the most dramatic loss in gasoline. In the heavy petroleum distillates, n-alkanes with even carbon numbers were degraded more than n-alkanes with odd carbon numbers.
Figure A “fully involved” house fire in Indianapolis, IN
相似文献
John V. GoodpasterEmail: |
18.
Two-dimensional liquid chromatography of synthetic polymers 总被引:2,自引:0,他引:2
Dušan Berek 《Analytical and bioanalytical chemistry》2010,396(1):421-441
Two-dimensional liquid chromatography, 2D-LC of synthetic polymers is critically assessed. Similarities and differences of
2D-LC of low-molecular-mass and polymeric substances are reviewed. The rationale of application of 2D-LC to macromolecular
substances is discussed. Basic information on retention mechanisms in liquid chromatography of synthetic polymers is furnished.
The principles, reasons, and significance of coupling of retention mechanisms are explained. The resulting separation processes
are elucidated, and the technical concepts of the corresponding experimental arrangements are described. The benefits of 2D-LC
are demonstrated together with numerous problems and shortcomings of the method.
相似文献
19.
20.
Xiaoshan Zhu Dayue Duan Steen Madsen Nelson G. Publicover 《Analytical and bioanalytical chemistry》2010,396(3):1345-1353
In this work, the compatibility of quantum dots (QDs) with immunobuffers was studied by investigating the fluorescence stability
of QDs in immunobuffers (in this research immunobuffers were defined as buffers for immunoaffinity binding or separation).
Experimentally, the fluorescence signals of QDs with different surface chemistries (amine-terminated, streptavidin-coated,
or antibody-conjugated) in commonly used immunobuffers were monitored versus time. The effect of some buffer composition on
the compatibility of QDs with these buffers was also explored. Based on experimental data, the QD compatibility with these
buffers is summarized, and it is found that a trace amount of bovine serum albumin added to most of these buffers helps QDs
to achieve compatibility with them. Moreover, with QD as fluorescence label and C-reactive protein as a model analyte, a magnetic
bead-based assay was performed using compatible and incompatible QD–immunobuffer systems. It is shown that compatible QD–immunobuffer
systems can be used to achieve a higher assay signal/background ratio.
相似文献