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1.
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: |
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.
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: |
4.
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: |
5.
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: |
6.
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: |
7.
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: |
8.
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: |
9.
10.
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: |
11.
Hitoshi Shirase Yurie Miura Yutaka Fukuda 《Monatshefte für Chemie / Chemical Monthly》2009,140(7):807-814
Abstract Mixed-ligand NiII complexes have been synthesized with 1,3-diketonate and bulky tri- or tetra-amine ligands. Their structures were determined
by X-ray crystallography, and solvatochromic behavior was examined by UV–vis–NIR spectroscopy. Steric effects of the bulky
ligands on the coordination distances and spectral properties are discussed.
Graphical Abstract
相似文献
Yutaka FukudaEmail: |
12.
Abstract The synthesis and acid-catalyzed rearrangement of novel thiazolomorphinandienes have been presented. An isomerization was
observed simultaneously with the backbone transformation. An extensive study was performed to determine the major effects
of the isomerization of 2′-alkyl- and aryl-substituted thiazoloapocodeines into 3′-alkyl- and arylisothiazoloapocodeines.
The obtained results provided another practical example of the reversible benzisothiazole–benzothiazole-type isomerization
emphasizing the determining role of the thermal effects in the occurrence of these isomerization products. The obtained experimental
results and the proposed mechanism were in agreement with the calculated DFT data.
Graphical abstract
相似文献
Attila SiposEmail: |
13.
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: |
14.
José ángel Rodríguez-Castrillón Mariella Moldovan J. Ignacio García Alonso 《Analytical and bioanalytical chemistry》2009,394(1):351-362
A method has been developed for the accurate determination of platinum by isotope dilution analysis, using enriched 194Pt, in environmental samples containing comparatively high levels of hafnium without any chemical separation. The method is
based on the computation of the contribution of hafnium oxide as an independent factor in the observed isotope pattern of
platinum in the spiked sample. Under these conditions, the ratio of molar fractions between natural abundance and isotopically
enriched platinum was independent of the amount of hafnium present in the sample. Additionally, mass bias was corrected by
an internal procedure in which the regression variance was minimised. This was possible as the mass bias factor for hafnium
oxide was very close to that of platinum. The final procedure required the measurement of three platinum isotope ratios (192/194,
195/194 and 196/194) to calculate the concentration of platinum in the sample. The methodology has been validated using the
reference material “BCR-723 road dust” and has been applied to different environmental matrices (road dust, air particles,
bulk wet deposition and epiphytic lichens) collected in the Aspe Valley (Pyrenees Mountains). A full uncertainty budget, using
Kragten’s spreadsheet method, showed that the total uncertainty was limited only by the uncertainty in the measured isotope
ratios and not by the uncertainties of the isotopic composition of platinum and hafnium.
Figure Simultaneous correction of hafnium oxide spectral interferences and mass bias in the determination of platinum in environmental
samples using isotope dilution analysis
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
Mariella MoldovanEmail: |
15.
Attila Sipos Miklós Tóth Franziska K. U. Mueller Jochen Lehmann Sándor Berényi 《Monatshefte für Chemie / Chemical Monthly》2009,140(4):473-478
Abstract The synthesis of 4H-thiochromene derivatives of apomorphines, a novel class of isoquinoline alkaloid-related compounds, has been achieved by
different O-dealkylation methods applied on previously published heteroring-fused aporphinoids. Detailed DFT study has been presented
regarding the mechanism of the L-selectride-mediated multiple O-dealkylation of a seven-ring aporphine analogue. Dopamine-binding tests confirmed the essential function of 11-hydroxy moiety
of the aporphine skeleton and revealed a remarkable D1 over D2 specificity for the derivative having the 4H-thiochromene ring system attached to positions 2 and 3 of the aporphine backbone.
Graphical Abstract
相似文献
Attila SiposEmail: |
16.
Edgar D. Goluch Bernhard Wolfrum Pradyumna S. Singh Marcel A. G. Zevenbergen Serge G. Lemay 《Analytical and bioanalytical chemistry》2009,394(2):447-456
Amperometric detection is ideally suited for integration into micro- and nanofluidic systems as it directly yields an electrical
signal and does not necessitate optical components. However, the range of systems to which it can be applied is constrained
by the limited sensitivity and specificity of the method. These limitations can be partially alleviated through the use of
redox cycling, in which multiple electrodes are employed to repeatedly reduce and oxidize analyte molecules and thereby amplify
the detected signal. We have developed an interdigitated electrode device that is encased in a nanofluidic channel to provide
a hundred-fold amplification of the amperometric signal from paracetamol. Due to the nanochannel design, the sensor is resistant
to interference from molecules undergoing irreversible redox reactions. We demonstrate this selectivity by detecting paracetamol
in the presence of excess ascorbic acid.
Figure
相似文献
Serge G. LemayEmail: |
17.
Marcus L. Young Suzanne Schnepp Francesca Casadio Andrew Lins Melissa Meighan Joseph B. Lambert David C. Dunand 《Analytical and bioanalytical chemistry》2009,395(1):171-184
Inductively coupled plasma-optical emission spectroscopy (ICP-OES) was used to determine the bulk metal elemental composition
of 62 modern bronze sculptures cast in Paris in the first half of the twentieth century from the collections of The Art Institute
of Chicago and the Philadelphia Museum of Art. As a result, a comprehensive survey of the alloy composition of the sculptures
of many prominent European artists of the early twentieth century is presented here for the first time. The sculptures in
this study consist of predominantly copper with two main alloying elements (zinc and tin). By plotting the concentrations
of these two elements (zinc and tin) against each other for all the sculptures studied, three clusters of data become apparent:
(A) high-zinc brass; (B) low-zinc brass; (C) tin bronze. These clusters correlate to specific foundries, which used specific
casting methods (sand or lost wax) that were influenced by individual preferences and technical skills of the foundry masters.
For instance, the high-zinc brass alloys (with the highest levels of tin and zinc and the lowest melting temperature) correspond
to most of the Picasso sculptures, correlate with the Valsuani foundry, and are associated with the most recent sculptures
(post-WWII) and with the lost-wax casting method. By expanding the ICP-OES database of objects studied, these material correlations
may become useful for identifying, dating, or possibly even authenticating other bronzes that do not bear foundry marks.
Figure
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
Francesca CasadioEmail: |
18.
Larissa S. Fenn Michal Kliman Ablatt Mahsut Sophie R. Zhao John A. McLean 《Analytical and bioanalytical chemistry》2009,394(1):235-244
The conformation space occupied by different classes of biomolecules measured by ion mobility-mass spectrometry (IM-MS) is
described for utility in the characterization of complex biological samples. Although the qualitative separation of different
classes of biomolecules on the basis of structure or collision cross section is known, there is relatively little quantitative
cross-section information available for species apart from peptides. In this report, collision cross sections are measured
for a large suite of biologically salient species, including oligonucleotides (n = 96), carbohydrates (n = 192), and lipids (n = 53), which are compared to reported values for peptides (n = 610). In general, signals for each class are highly correlated, and at a given mass, these correlations result in predicted
collision cross sections that increase in the order oligonucleotides < carbohydrates < peptides < lipids. The specific correlations
are described by logarithmic regressions, which best approximate the theoretical trend of increasing collision cross section
as a function of increasing mass. A statistical treatment of the signals observed within each molecular class suggests that
the breadth of conformation space occupied by each class increases in the order lipids < oligonucleotides < peptides < carbohydrates.
The utility of conformation space analysis in the direct analysis of complex biological samples is described, both in the
context of qualitative molecular class identification and in fine structure examination within a class. The latter is demonstrated
in IM-MS separations of isobaric oligonucleotides, which are interpreted by molecular dynamics simulations.
Figure Potential for performing simultaneous “omics” through the separation of biomolecular classes on the basis of structure and
mass using ion mobility-mass spectrometry
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
John A. McLeanEmail: |
19.
Edward B. Nikitin Sanjeev K. Dey David A. Lightner 《Monatshefte für Chemie / Chemical Monthly》2009,140(1):97-110
Abstract Six 10-nor-bilirubin analogs have been synthesized and investigated. Lacking the C(10) CH2 group, these linear tetrapyrroles have a bipyrrole core rather than a dipyrrylmethane core and thus a different shape. Whereas
the propionic acid groups of bilirubin are well engaged in intramolecular hydrogen bonding to the dipyrrinones, molecular
modeling studies of the 10-nor-rubins predict that propionic acid chains are too short to engage the CO2H hydrogen fully in intramolecular hydrogen bonding with the dipyrrinones. Butyric acid chains, however, can and do lead to
a stabilized conformation with a bipyrrole dihedral angle of approximately 115°. Spectroscopic studies verify the predictions
and vapor pressure osmometry indicates that the 10-nor-rubins with butyric acids are monomeric in CHCl3.
Graphical abstract
相似文献
David A. LightnerEmail: |
20.
A novel on-column sequential preconcentration method based on the combination of field-amplified sample injection induced
by acetonitrile and pseudo isotachophoresis (ITP)–acid stacking is developed for simply but efficiently concentrating alkaloid
cations in a high-salt sample matrix in capillary electrophoresis. Acetonitrile (70%) added to a sample solution with a high-salt
sample matrix not only induces field-amplified sample stacking by decreasing conductivity but also acts as a termination reagent
in the succeeding pseudo ITP. After sample injection had been completed, a plug of H+ was injected electrokinetically and a neutralization reaction between H+ and tartrate from the buffer solution produced a low conductivity zone, in which the injected analyte cations were further
concentrated. With the sequential preconcentration method, a 3 orders of magnitude detection sensitivity (1,400-fold) increase
could be observed compared with the conventional electrokinetic injection method, without compromising separation efficiency
and peak shape, and detection limits of 0.1 ng/mL for myosmine and 0.3 ng/mL for anabasine with the conditions selected were
achieved. The calibration curves demonstrated good linearity in the concentration ranges 1.3–600 ng/mL for myosmine and 4.9–900 ng/mL
for anabasine, respectively. The proposed method has been used to analyze successfully trace alkaloids in cigarette samples.
Figure Sequential preconcentration processes: a sample injection; b introduction of HCl; c capillary zone electrophoresis separation. A
−
tartrate, white circles acetonitrile, black circles Na+, sample zone, myosmine, anabasine 相似文献