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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.
Microfluidics offers an ideal platform to integrate cell-based assays with electric measurements. The technological advances
in microfluidics, microelectronics, electrochemistry, and electrophysiology have greatly inspired the development of microfluidic/electric
devices that work with a low number of cells or single cells. The applications of these microfluidic systems range from the
detecting of cell culture density to the probing of cellular functions at the single-cell level. In this review, we introduce
the recent advances in the electric analysis of cells on a microfluidic platform, specifically related to the quantification
and monitoring of cells in static solution, on-chip patch-clamp measurement, and examination of flowing cells. We also point
out future directions and challenges in this field.
Figure Different microfluidic devices applied to electrical analysis of cells 相似文献
3.
We report the multiplexed, simultaneous analysis of antigen–antibody interactions that involve human immunoglobulin G (IgG)
on a gold substrate by the surface plasmon resonance imaging method. A multichannel, microfluidic chip was fabricated from
poly(dimethylsiloxane) (PDMS) to selectively functionalize the surface and deliver the analyte solutions. The sensing interface
was constructed using avidin as a linker layer between the surface-bound biotinylated bovine serum albumin and biotinylated
anti-human IgG antibodies. Four mouse anti-human IgG antibodies were selected for evaluation and the screening was achieved
by simultaneously monitoring protein–protein interactions under identical conditions. Antibody–antigen binding affinities
towards human immunoglobulin were quantitatively compared by employing Langmuir adsorption isotherms for the analysis of SPRi
responses obtained under equilibrium conditions. We were able to identify two IgG samples with higher affinities towards the
target, and the determined binding kinetics falls within the typical range of values reported in the literature. Direct measurement
of proteins in serum samples by SPR imaging was achieved by developing methods to minimize nonspecific adsorption onto the
avidin-functionalized surface, and a limit of detection (LOD) of 6.7 nM IgG was obtained for the treated serum samples. The
combination of SPR imaging and multichannel PDMS chips offers convenience and flexibility for sensitive and label-free measurement
of protein–protein interactions in complex conditions and enables high-throughput screening of pharmaceutically significant
molecules.
Figure Microchannel SPR imaging for protein–protein interactions 相似文献
4.
Zaher M Ravelet C Baussanne I Ravel A Grosset C Décout JL Peyrin E 《Analytical and bioanalytical chemistry》2009,393(2):655-660
In this paper, we describe the preparation and the evaluation of a porous graphitic carbon (PGC) column coated with a new
dinaphthyl derivative of neamine for chiral ligand-exchange (LE) chromatography. It was shown that the graphitic surface/dinaphthyl
anchor system efficiently (1.15 μmol/m2) and stably (three months of intensive use) adsorbs the neamine template onto the chromatographic support. The resulting
coated PGC stationary phase showed appreciable LE-based enantioselective properties towards several native amino acids.
Chromatographic separation of methionine enantiomers using a dinaphtyl neamine-based ligand-exchange chiral stationary phase 相似文献
5.
Traditional methods for protein kinase (PK) assay are mainly based on use of 32P-labeled adenosine triphosphate (ATP); applications of such methods are, however, hampered by radioactive waste and short
half-life of 32P-labeled ATP. Therefore non-radioactive methods, such as fluorescence detection techniques are good alternative. In this
review, we describe the principles of four fluorescence techniques (fluorescence intensity endpoint measurement, fluorescence
resonance energy transfer (FRET), fluorescence polarization (FP), and fluorescence lifetime imaging) and provide an overview
of applications of these fluorescence detection techniques in protein kinase assay, underlining their relative advantages
and limitations. Research trends in this field are also highlighted.
Figure Schematic representation of kinase assay based on direct fluorescence polarization measurements. The fluorescent peptide,
on phosphorylation by kinase, binds to a phosphospecific antibody, which leads to a high FP value 相似文献
6.
Astel A Tsakovski S Simeonov V Reisenhofer E Piselli S Barbieri P 《Analytical and bioanalytical chemistry》2008,390(5):1283-1292
The present study deals with the application of self-organizing maps (SOM) and multiway principal-components analysis to classify,
model, and interpret a large monitoring data set for surface water quality. The chemometric methods applied made it possible
to reveal specific quality patterns of the chemical and biological parameters used to monitor the water quality (relation
between water temperature, turbidity, hardness, colibacteria), seasonal impacts during the long period of observation and
the relative independence on the spatial location of the sampling sites (water supply sources for the City of Trieste).
Figure The schematic procedure for surface water pollution estimation supported by neural network-based classification and multivariate factor
analysis 相似文献
7.
In-torch LA–ICP–MS was implemented into an in-house-built ICP–TOFMS system. The fast data acquisition capabilities of the
new configuration allowed simultaneous multi-element measurement and readout of in-torch LA–ICP–MS signals with 30 μs time
resolution. The measurements confirmed previously observed fine structures of in-torch generated signals and provided new
insights in the dynamic processes in the plasma on a microsecond time scale. The new setup is described in detail and first
figures of merit are given.
Figure Time dependent multi element signal after laser ablation in the torch of an ICP-TOFMS instrument 相似文献
8.
9.
A fiberoptic evanescent-wave sensor has been developed for the measurement of antinuclear antibodies in sera from patients
and healthy individuals. The sensor was constructed on the basis of modification of the unclad portion of an optical fiber
with self-assembled gold colloids, where the colloidal gold surface was further functionalized with extractable nuclear antigens.
Results show that detection of antinuclear antibodies by this sensor agrees quantitatively with the clinically accepted enzyme-linked
immunosorbent assay (ELISA) method. This sensing platform has the following advantages: label-free and real-time detection
capability, simple to construct and use, highly sensitive, and does not require a secondary antibody. The sensitivity of this
platform is at least an order of magnitude higher than that of the ELISA method and thus may lead to a new direction in recognition
of immune response.
Biomolecular binding of antinuclear antibodies (ANA) with extractable nuclear antigens (ENA)-functionalized gold nanoparticles
results in a change of surface plasmon absorption. When light propagates in an optical fiber by multiple total internal reflection,
such a change in signal can be significantly enhanced. 相似文献
10.
11.
Sum-frequency generation (SFG) is a nonlinear laser-spectroscopy technique suitable for analysis of adsorbed molecules. The
sub-monolayer sensitivity of SFG spectroscopy enables vibrational spectra to be obtained with high specificity for a variety
of molecules on a range of surfaces, including metals, oxides, and semiconductors. The use of ultra-short laser pulses on
time-scales of picoseconds also makes time-resolved measurements possible; this can reveal ultrafast transient changes in
molecular arrangements. This article reviews recent time-resolved SFG spectroscopy studies revealing site-hopping of adsorbed
CO on metal surfaces and the dynamics of energy relaxation at water/metal interfaces.
Time-resolved sum frequency generation spectroscopy at surfaces with non-resonant laser pulse irradiation 相似文献
12.
Amino acids are important targets for metabolic profiling. For decades, amino acid analysis has been accomplished by either
cation-exchange or reversed-phase liquid chromatography coupled to UV absorbance or fluorescence detection of pre-column or
post-column-derivatized amino acids. Recent years have seen great progress in the development of direct-infusion or hyphenated
mass spectrometry in the analysis of free amino acids in physiological fluids, because mass spectrometry not only matches
optical detection in sensitivity, but also offers superior selectivity. The advent of cryo-probes has also brought NMR spectroscopy
within the detection limits required for the analysis of free amino acids. But there is still room for further improvement,
including expansion of the analyte spectrum, reduction of sample preparation and analysis time, automation, and synthesis
of affordable isotope standards.
Figure Fully automated gas chromatography-mass spectrometry analysis of amino acids. 相似文献
13.
Martinez Vazquez R Osellame R Cretich M Chiari M Dongre C Hoekstra HJ Pollnau M van den Vlekkert H Ramponi R Cerullo G 《Analytical and bioanalytical chemistry》2009,393(4):1209-1216
We use direct femtosecond laser writing to integrate optical waveguides into a commercial fused silica capillary electrophoresis
chip. High-quality waveguides crossing the microfluidic channels are fabricated and used to optically address, with high spatial
selectivity, their content. Fluorescence from the optically excited volume is efficiently collected at a 90° angle by a high
numerical aperture fiber, resulting in a highly compact and portable device. To test the platform we performed electrophoresis
and detection of a 23-mer oligonucleotide plug. Our approach is quite powerful because it allows the integration of photonic
functionalities, by simple post-processing, into commercial LOCs fabricated with standard techniques.
Figure Femtosecond laser written waveguides can selectively excite fluorescence in a microfluidic channel of a commercial lab-on-a-chip.
A compact scheme for on-chip detection by laser induced fluorescence is applied to capillary electrophoresis of a 23-mer Cy3-labeled
oligonucleotide 相似文献
14.
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
15.
Nora Graf Thomas Gross Thomas Wirth Wilfried Weigel Wolfgang E. S. Unger 《Analytical and bioanalytical chemistry》2009,393(8):1907-1912
The chemical composition of the functional surfaces of substrates used for microarrays is one of the important parameters
that determine the quality of a microarray experiment. In addition to the commonly used contact angle measurements to determine
the wettability of functionalized supports, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry
(ToF-SIMS) are more specific methods to elucidate details about the chemical surface constitution. XPS yields information
about the atomic composition of the surface, whereas from ToF-SIMS, information on the molecular species on the surface can
be concluded. Applied on printed DNA microarrays, both techniques provide impressive chemical images down to the micrometer
scale and can be utilized for label-free spot detection and characterization. Detailed information about the chemical constitution
of single spots of microarrays can be obtained by high-resolution XPS imaging.
Figure Eye-catching image for the graphical online abstract 相似文献
16.
Nicolas F. Y. Durand Elli Saveriades Philippe Renaud 《Analytical and bioanalytical chemistry》2009,394(2):421-425
In this work, we present theoretical and experimental studies of nanofluidic channels as a potential biosensor for measuring
rapid protein complex formation. Using the specific properties offered by nanofluidics, such as the decrease of effective
diffusion of biomolecules in confined spaces, we are able to monitor the binding affinity of two proteins. We propose a theoretical
model describing the concentration profile of proteins in a nanoslit and show that a complex composed by two bound biomolecules
induces a wider diffusion profile than a single protein when driven through a nanochannel. To validate this model experimentally,
we measured the increase of the fluorescent diffusion profile when specific biotinylated dextran was added to fluorescent
streptavidin. We report here a direct and relatively simple technique to measure the affinity between proteins.
Figure We present theoretical and experimental studies of nanofluidic channels as potential biosensors for rapidly measuring protein
complex formation. Our system is based on steady-state diffusion effects which are observed inside a nanoslit. 相似文献
17.
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
18.
Bai LP Cai Z Zhao ZZ Nakatani K Jiang ZH 《Analytical and bioanalytical chemistry》2008,392(4):709-716
Spectrofluorometric titration, electrospray ionization time-of-flight mass spectrometric and UV melting methods were employed
to study the binding of chelerythrine and sanguinarine to bulged DNA. The results showed that both alkaloids bind specifically
to single pyrimidine (C, T) bulge sites. The ability of sanguinarine to bind to both regular and bulged hairpins was found
to be stronger than that of chelerythrine, but the binding selectivity of chelerythrine toward single-base bulges was much
larger than that of sanguinarine.
Figure Association constants for chelerythrine and sanguinarine toward regular and single-base bulged hairpins obtained from fluorometric
analysis 相似文献
19.
Surface acoustic wave biosensors: a review 总被引:2,自引:0,他引:2
This review presents an overview of 20 years of worldwide development in the field of biosensors based on special types of
surface acoustic wave (SAW) devices that permit the highly sensitive detection of biorelevant molecules in liquid media (such
as water or aqueous buffer solutions). 1987 saw the first approaches, which used either horizontally polarized shear waves
(HPSW) in a delay line configuration on lithium tantalate (LiTaO3) substrates or SAW resonator structures on quartz or LiTaO3 with periodic mass gratings. The latter are termed “surface transverse waves” (STW), and they have comparatively low attenuation
values when operated in liquids. Later Love wave devices were developed, which used a film resonance effect to significantly
reduce attenuation. All of these sensor approaches were accompanied by the development of appropriate sensing films. First
attempts used simple layers of adsorbed antibodies. Later approaches used various types of covalently bound layers, for example
those utilizing intermediate hydrogel layers. Recent approaches involve SAW biosensor devices inserted into compact systems
with integrated fluidics for sample handling. To achieve this, the SAW biosensors can be embedded into micromachined polymer
housings. Combining these two features will extend the system to create versatile biosensor arrays for generic lab use or
for diagnostic purposes.
SAW based biosensor immersed in a sample flow. Analyte molecules binding to the immobilized antibodies on the sensor surface
will influence the velocity of the SAW and hence the output signal generated by the driving electronics. 相似文献
20.
Nagl S Stich MI Schäferling M Wolfbeis OS 《Analytical and bioanalytical chemistry》2009,393(4):1199-1207
Chemical sensing, imaging and microscopy based on the use of fluorescent probes has so far been limited almost exclusively
to the detection of a single parameter at a time. We present a scheme that can overcome this limitation by enabling optical
sensing of two parameter simultaneously and even at identical excitation and emission wavelengths of two probes provided (a)
their decay times are different enough to enable two time windows to be recorded, and (b) the emission of the shorter-lived
probe decays to below the detectable limit while that of the other still can be measured. We refer to this new scheme as the
dual lifetime determination (DLD) method and show that it can be widely varied by appropriate choice of probes and experimental
settings. DLD is demonstrated to work by sensing oxygen and temperature independently from each other by making use of two
probes, one for oxygen (a platinum porphyrin dissolved in polystyrene), and one for temperature [a europium complex dissolved
in poly(vinyl methylketone)]. DLD was applied to monitor the consumption of oxygen in the glucose oxidase-catalyzed oxidation
of glucose at varying temperatures. The scheme is expected to have further applications in cellular assays and biophysical
imaging.
Figure Principle behind the dual lifetime determination (DLD) method 相似文献