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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.
Kowalczyk A Nowicka AM Karbarz M Stojek Z 《Analytical and bioanalytical chemistry》2008,392(3):463-469
A piece of dry N-isopropylacrylamide polymer was soaked in phosphate buffer to obtain a hydrogel which was then employed in the examination
of interactions between an anticancer drug C-1311 (5-diethylaminoethyl-amino-8-hydroxyimidazoacridinone) and dsDNA. dsDNA
was introduced into the polymer at the polymerization stage. The drug was added to the buffer. Using the volume phase transition
of the gel at 40 °C, the unbound drug could be determined in the solution released during the transition, which made the calculations
more reliable. The interaction parameters were calculated using the McGhee and von Hippel model. It appeared that in the gel
medium, the interaction between the drug and dsDNA is spatially limited, since the number of binding units of the polymer
chain occupied by one drug molecule was found to be one, while it was two in the regular buffer solution.
Figure
The two authors Agata Kowalczyk and Anna M. Nowicka contributed equally to this work. 相似文献
3.
Tse Sum Bui B Belmont AS Witters H Haupt K 《Analytical and bioanalytical chemistry》2008,390(8):2081-2088
A β-estradiol receptor binding mimic was synthesised using molecular imprinting. Bulk polymers and spherical polymer nanoparticles
based on methacrylic acid and ethylene glycol dimethacrylate as the functional monomer and crosslinker, respectively, were
prepared in acetonitrile. The selectivity was evaluated by radioligand binding assays. The imprinted polymers were very specific
to β-estradiol since the control polymers bound virtually none of the radioligand. The bulk polymer was then employed to screen
endocrine disrupting chemicals. Structurally related steroids like α-estradiol, estrone and ethynylestradiol showed, respectively,
14.0, 5.0 and 0.7% of relative binding to the β-estradiol polymer, whereas most unrelated chemicals did not bind at all. These
results are compared to those obtained with a bioassay using stably transfected yeast cells in culture bearing the human estrogen
receptor. The receptor was activated by several estrogen-like chemicals and to a lesser extent by some structurally related
chemicals.
Figure A molecularly imprinted polymer that was a synthetic receptor for beta-estradiol was used for the screening of endocrine disrupting
chemicals that are structurally related or unrelated to beta-estradiol. The results were compared with the recognition of
the compounds by the biological estrogen receptor expressed in yeast cells. Related steroids like alpha-estradiol, estrone
and ethynylestradiol showed significant binding to the beta-estradiol imprinted polymer, whereas most unrelated chemicals
did not bind. The biological receptor was activated by several estrogen-like chemicals, and to a lesser extent by some structurally
related chemicals 相似文献
4.
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
5.
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
6.
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8.
Cruz Enriquez A Rivero Espejel IA Andrés García E Díaz-García ME 《Analytical and bioanalytical chemistry》2008,391(3):807-815
The interaction of 11-mercaptoundecanoic acid capped gold nanoparticles (MUA-GNPs) with europium ions and aminoacids has been
studied by UV-Vis spectrophotometry, fluorescence, confocal fluorescence microscopy, resonance light scattering and TEM. Results
demonstrated that hyper-Rayleigh scattering emission occurs upon the addition of lysine to the MUA-GNPs–Eu(III) system, thus
providing an inherently sensitive method for lysine determination. The effects of geometrical factors of the gold nanoparticles
(aspect ratio, particle size, cluster formation) and the surrounding medium (pH) on this behavior are discussed. The cooperative
binding interactions of Eu3+ and lysine with gold nanoparticles permitted the discrimination of lysine from other amino acids. The probable mechanism
for the spectral changes and the enhanced resonance light scattering observed is outlined.
Figure Gold nanoparticle resonance light scattering plasmon enhancement through cooperative binding with europium and lysine 相似文献
9.
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.
相似文献
10.
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
11.
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
12.
Jackson AT Slade SE Thalassinos K Scrivens JH 《Analytical and bioanalytical chemistry》2008,392(4):643-650
The end-group functionalisation of a series of poly(propylene glycol)s has been characterised by means of electrospray ionisation–tandem
mass spectrometry (ESI-MS/MS). A series of peaks with mass-to-charge ratios that are close to that of the precursor ion were
used to generate information on the end-group functionalities of the poly(propylene glycol)s. Fragment ions resulting from
losses of both of the end groups were noted from some of the samples. An example is presented of how software can be used
to significantly reduce the length of time involved in data interpretation (which is typically the most time-consuming part
of the analysis).
Figure Screenshot from Polymerator software of annotated ESI-MS/MS spectrum from the lithiated heptamer of poly(propylene glycol)
di-acrylate 相似文献
13.
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
14.
Brambilla R Pinto CF Miranda MS dos Santos JH 《Analytical and bioanalytical chemistry》2008,391(7):2673-2681
A series of octadecylsilane-modified silicas were prepared by sol-gel and grafting methods. Carbon contents and octadecyl
chain conformations were shown to depend on the preparative route. Grafting engenders a low carbon content and a liquid-like
chain conformation, while the sol-gel method affords a much higher carbon content and a crystalline conformation. The relationships
between the toluene adsorption of the hybrid silicas and their chain conformations, their carbon contents and their textural
characteristics are discussed. These sorbents, when used in combination with ultraviolet diffuse reflectance spectroscopy
(UV DRS), can be employed as a rapid screening method for detection of aromatic compounds in water and air environmental matrices.
Figure Octadecylsilane-modified silicas in the adsorption of toluene 相似文献
15.
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
16.
Applications of microelectromechanical systems (MEMS) technology are widespread in both industrial and research fields providing
miniaturized smart tools. In this review, we focus on MEMS applications aiming at manipulations and characterization of biomaterials
at the single molecule level. Four topics are discussed in detail to show the advantages and impact of MEMS tools for biomolecular
manipulations. They include the microthermodevice for rapid temperature alternation in real-time microscopic observation,
a microchannel with microelectrodes for isolating and immobilizing a DNA molecule, and microtweezers to manipulate a bundle
of DNA molecules directly for analyzing its conductivity. The feasibilities of each device have been shown by conducting specific
biological experiments. Therefore, the development of MEMS devices for single molecule analysis holds promise to overcome
the disadvantages of the conventional technique for biological experiments and acts as a powerful strategy in molecular biology.
Figure Towards single bio molecular handling and characterization by MEMS 相似文献
17.
Following a recently developed concept of MS binding assays based on the quantification of a native marker by LC–MS a procedure
to study binding of a low-affinity marker in kinetic, saturation, and competition experiments was established. Separation
of bound and unbound marker—the most crucial step of the assay—could be effectively achieved by filtration in a 96-well-format.
MS binding assays according to this procedure allowed the reliable characterization of NO 711 binding to mGAT1 in presence
of physiological NaCl concentrations. Comparing the results obtained in the present study with those from experiments using
1 mol L−1 NaCl in the incubation milieu reveals remarkable differences with respect to the marker’s affinity and kinetics and to the
investigated test compound’s potency.
Principle of MS binding assays After incubation of a target with a native marker, bound and unbound marker are separated by filtration. Subsequently, the
bound native marker is liberated from the target and finally quantified by LC-MS-MS.
Dedicated to Prof. Hans-Dietrich Stachel on the occasion of his 80th birthday 相似文献
18.
Six molecularly imprinted polymers (MIPs) of erythromycin (ERY) were prepared by noncovalent bulk polymerization using methacrylic
acid (MAA) as the functional monomer. On the basis of binding analysis, the MIPs with 1:2 optimum ratio of template to MAA
were selected for subsequent scanning electron microscopy and Brunauer–Emmett–Teller analyses, which indicated that the MIPs
had more convergent porous structures than the nonimprinted polymers. The equilibrium binding experiments showed that the
binding sites of MIPs were heterogeneous, with two dissociation constants of 0.005 and 0.63 mg mL−1, respectively. Furthermore, the performance of the MIPs as solid-phase extraction (SPE) sorbents was evaluated, and the selectivity
analysis showed that the MIPs could recognize ERY with moderate cross-reactivity for other macrolides. The overall investigation
of molecularly imprinted SPE for cleanup and enrichment of the ERY in pig muscle and tap water confirmed the feasibility of
utilizing the MIPs obtained as specific SPE sorbents for ERY extraction in real samples.
Figure Schematic diagram of the preparation and application of the erythromycin imprinted molecularly imprinted polymers
Suquan Song and Aibo Wu contributed equally to this work. 相似文献
19.
Välimaa L Ylikotila J Kojola H Soukka T Takalo H Pettersson K 《Analytical and bioanalytical chemistry》2008,391(6):2135-2144
Direct measurement of time-resolved fluorescence from a washed surface of an immunoassay well constitutes an advantage compared
with label development options involving signal generation in solution. Epi-fluorometric detection collects the signal from
only a small part of the microtiter well’s bottom surface and it is inadequate for the optimal assay sensitivity when using
binding surfaces introduced by large coating volume. This study reports on the use of streptavidin-coated spots intended to
condense the binding of the labeled antibodies to coincide with the excitation beam. The spots were generated in special microtiter
wells containing 2.5-mm, 3.5-mm, and 4.5-mm diameter indentations by adsorption from liquid droplets containing either native
(SAv) or modified high-capacity (GA-SAv) streptavidin. The SAv-coated and GA-SAv-coated spots exhibited maximum Eu–biotin
binding densities of 0.080 and 0.47 pmol/mm2, respectively. A sandwich-type immunoassay of thyroid-stimulating hormone (TSH) provided a fivefold to sixfold increase in
the signal-to-background ratios of the spot assay and an equivalent improvement in the detection limit (DL < 0.01 mU/L) compared
with a reference assay.
Figure The condensation of the binding area into a spot (right) results in a denser collection of the labeled antibodies and more favorable signal-to-background ratios compared with a
regular approach using a large binding area (left) 相似文献
20.
In proteomics, nanoflow multidimensional chromatography is now the gold standard for the separation of complex mixtures of
peptides as generated by in-solution digestion of whole-cell lysates. Ideally, the different stationary phases used in multidimensional
chromatography should provide orthogonal separation characteristics. For this reason, the combination of strong cation exchange
chromatography (SCX) and reversed-phase (RP) chromatography is the most widely used combination for the separation of peptides.
Here, we review the potential of hydrophilic interaction liquid chromatography (HILIC) as a separation tool in the multidimensional
separation of peptides in proteomics applications. Recent work has revealed that HILIC may provide an excellent alternative
to SCX, possessing several advantages in the area of separation power and targeted analysis of protein post-translational
modifications.
Figure Artistic impression of the HILIC separation mechanism 相似文献