共查询到20条相似文献,搜索用时 218 毫秒
1.
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
2.
Bonanni A Esplandiu MJ Pividori MI Alegret S del Valle M 《Analytical and bioanalytical chemistry》2006,385(7):1195-1201
Impedance spectroscopy is proposed as the transduction principle for detecting the hybridization of DNA complementary strands.
In our experiments, different DNA oligonucleotides were used as model gene substances. The gene probe is first immobilized
on a graphite-epoxy composite working electrode based genosensor. Detection principle is based on changes of impedance spectra
of a redox marker, the ferro/ferricyanide couple, after hybridization with target DNA. Resistance offered to the electrochemical
reaction serves as the working signal, allowing for an unlabelled gene assay.
相似文献
3.
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
4.
We quantitatively modeled the volume phase transition of a hydrogel containing a crystalline colloidal array with a crown
ether ligand which binds Pb2+. The hydrogel volume response and the wavelength diffracted depend on the Pb2+ concentration and on both the ionic strength and the valence of the nonbinding ionic species. We successfully modeled the
response of this hydrogel Pb2+ sensor to ionic strength and the cation valence of the added salts.
Figure Cation identity dependence of crown ether photonic crystal Pb+ sensing 相似文献
5.
Kaewkhomdee N Kalambaheti C Predapitakkun S Siripinyanond A Shiowatana J 《Analytical and bioanalytical chemistry》2006,386(2):363-369
The forms and quantities of iron species in corrosion product samples from natural gas pipelines were examined, using a continuous-flow
sequential extraction system. Sequential extraction consists of four steps that dissolve water soluble iron (FeSO4), acid soluble iron (FeCO3), reducible iron (Fe-(oxyhydr)oxides) and oxidisable iron (FeS2) fractions, respectively. Selectivity of extracting reagents for particular iron species was evaluated by determination of
co-extracted anions, using ion chromatography, and evolved CO2, using indirect flame atomic absorption spectrometer (FAAS). Iron was found predominantly in the reducible fraction (61–99%),
indicating that Fe-(oxyhydr)oxides are the major constituents of the corrosion products.
相似文献
6.
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.
相似文献
7.
Vasylevska AS Karasyov AA Borisov SM Krause C 《Analytical and bioanalytical chemistry》2007,387(6):2131-2141
A new family of coumarin-based pH indicators was synthesized. They are sensitive to pH in either weakly acidic or weakly basic
solution. The indicators possess moderate to high brightness, excellent photostability and compatibility with light-emitting
diodes. The indicators were covalently immobilized on the surface of amino-modified polymer microbeads which in turn were
incorporated into a hydrogel matrix to obtain novel pH-sensitive materials. When a mixture of two different microbeads is
used, the membranes are capable of optical pH sensing over a very wide range comparable to the dynamic range of the glass
electrode (pH 1–11).
A new family of coumarin-based pH indicators is synthesized for the use in either weakly acidic or weakly basic solution.
The indicators possess moderate to high brightness, excellent photostability and compatibility with light-emitting diodes.
Novel pH-sensitive materials are obtained by covalent immobilization of the indicators on the surface of amino-modified polymer
microbeads which in turn are incorporated into a hydrogel matrix. Sensing of pH over a very wide range also becomes possible. 相似文献
8.
A chemiluminescent (CL) detection method has been developed for DNA hybridization. The assay relies on a sandwich-type DNA
hybridization in which gold nanoparticles modified with alkylthiol-capped oligonucleotide strands are used as probes to monitor
the presence of the specific target DNA. The , which is the dissolving product of the gold nanoparticles anchored on the DNA hybrids, serves as an analyte in the H2O2–luminol– CL reaction for the indirect measurement of the target DNA. The combination of the remarkable sensitivity of the CL analysis
with the large number of released from each DNA hybrid allows a detection limit at levels as low as 0.1 pM of the target DNA. Moreover, with a further
silver amplification step, the detection limit will be pushed down to the femtomolar domain.
相似文献
9.
Moschou EA Nicholson AD Jia G Zoval JV Madou MJ Bachas LG Daunert S 《Analytical and bioanalytical chemistry》2006,385(3):596-605
This work demonstrates the development of microfluidic compact discs (CDs) for protein purification and fractionation integrating a series of microfluidic features, such as microreservoirs, microchannels, and microfluidic fractionators. The CDs were fabricated with polydimethylsiloxane (PDMS), and each device contained multiple identical microfluidic patterns. Each pattern employed a microfluidic fractionation feature with operation that was based on the redirection of fluid into an isolation chamber as a result of an overflow. This feature offers the advantage of automated operation without the need for any external manipulation, which is independent of the size and the charge of the fractionated molecules. The performance of the microfluidic fractionator was evaluated by its integration into a protein purification microfluidic architecture. The microfluidic architecture employed a microchamber that accommodated a monolithic microcolumn, the fractionator, and an isolation chamber, which was also utilized for the optical detection of the purified protein. The monolithic microcolumn was polymerized “in situ” on the CD from a monolith precursor solution by microwave-initiated polymerization. This technique enabled the fast, efficient, and simultaneous polymerization of monoliths on disposable CD microfluidic platforms. The design of the CD employed allows the integration of various processes on a single microfluidic device, including protein purification, fractionation, isolation, and detection.
相似文献
10.
Sulfur has been detected in a spectral window (around 868 nm) previously unexplored by laser-induced breakdown spectrometry
(LIBS), using an ablation laser with an ultraviolet wavelength, a gated detector, and inert ambient gas at a low, controlled
pressure. This spectral window enables new-generation gated iCCD cameras to be used, which have adequate quantum efficiencies
up to 900 nm. Application of our technique can substantially improve signal strength and thus extends the ability of LIBS
to detect many nonmetallic elements.
相似文献
11.
Development and field evaluation of a new diffusive sampler for Hydrogen Sulphide in the ambient air
De Santis F Allegrini I Bellagotti R Vichi F Zona D 《Analytical and bioanalytical chemistry》2006,384(4):897-901
A diffusive sampler for the determination of hydrogen sulphide (H2S) based on collection on a paper filter coated with silver nitrate followed by optical densitometric determination of the
metal sulphide was developed. Laboratory tests were conducted in controlled atmosphere to evaluate linearity, uptake rate,
face velocity effects, sample stability, influence of relative humidity and of interferents, precision and accuracy. The measured
uptake rate for H2S was determined in experiments involving sampling at different concentration levels in comparison to a wet standard colorimetric
technique. The precision of the measurements for co-located passive samplers was lower than 15%. The accuracy of the data
collected is within 20% of the actual value measured by the wet method. The sampler is capable of reliable measurements of
H2S at common levels of a polluted atmosphere in urban settings yielding average concentration levels over one month and beyond.
Diffusive sampling can be adopted to analyse in detail the temporal and spatial trends of H2S concentration in ambient air and in specific historic buildings or in museums.
Figure At the end of sampling cap #2 is removed and optical density is measured 相似文献
12.
The detection and identification of dilute bacterial samples by surface-enhanced Raman spectroscopy has been explored by mixing
aqueous suspensions of bacteria with a suspension of nanocolloidal silver particles. An estimate of the detection limit of
E. coli was obtained by varying the concentration of bacteria. By correcting the Raman spectra for the broad librational OH band
of water, reproducible spectra were obtained for E. coli concentrations as low as approximately 103 cfu/mL. To aid in the assignment of Raman bands, spectra for E. coli in D2O are also reported.
Figure Light scattering apparatus used to detect bacteria 相似文献
13.
The use of electrochemical impedance spectroscopy for biosensing 总被引:1,自引:0,他引:1
This review introduces the basic concepts and terms associated with impedance and techniques of measuring impedance. The focus
of this review is on the application of this transduction method for sensing purposes. Examples of its use in combination
with enzymes, antibodies, DNA and with cells will be described. Important fields of application include immune and nucleic
acid analysis. Special attention is devoted to the various electrode design and amplification schemes developed for sensitivity
enhancement. Electrolyte insulator semiconductor (EIS) structures will be treated separately.
Figure An alternating current which is forced to pass an interface is sensitive to surface changes and will detect impedance changes
due to biomolecule immobilisation or formation of a recognition complex. This can be used for the construction of biosensor
electrodes 相似文献
14.
McCarthy EL Egeler TJ Bickerstaff LE Pereira da Cunha M Millard PJ 《Analytical and bioanalytical chemistry》2006,386(7-8):1975-1984
Unique base sequences derived from RNA of both infectious hematopoietic necrosis virus (IHNV) and infectious salmon anemia
virus (ISAV) were detected and identified using a combination of surface-associated molecular padlock DNA probes (MPPs) and
rolling circle amplification (RCA) in microcapillary tubes. DNA oligonucleotides with base sequences identical to RNA obtained
from IHNV or ISAV were recognized by MPPs. Circularized MPPs were then captured on the inner surfaces of glass microcapillary
tubes by immobilized DNA oligonucleotide primers. Extension of the immobilized primers by isothermal RCA produced DNA concatamers,
which were labeled with fluorescent SYBR Green II nucleic acid stain, and measured by microfluorimetry. Molecular padlock
probes, combined with this method of surface-associated isothermal RCA, exhibited high selectivity without the need for thermal
cycling. This method is applicable to the design of low-power field sensors capable of multiplex detection of viral, bacterial,
and protozoan pathogens within localized regions of microcapillary tubes.
相似文献
15.
Pyochelin is a siderophore and virulence factor common to Burkholderia cepacia and several Pseudomonas strains. It is isolated from bacterial media as a mixture of two epimers, which readily equilibrate in most solvents. Experiments based on high-performance liquid chromatography/electrospray ionization mass spectrometry are reported here, allowing the investigation of the different Fe(III)-chelating properties of pyochelin diastereomers in solution without the need for labourious isolation. It is demonstrated in this study that only one of the two pyochelin diastereomers is able to chelate Fe(III); no Fe(III) complexes of the other diastereomer could be detected. The Fe(III)–pyochelin complex exhibited a 1:1 metal-to-siderophore ratio and no evidence for other stoichiometries was found.
相似文献
16.
Tastet L Schaumlöffel D Bouyssiere B Lobinski R 《Analytical and bioanalytical chemistry》2006,385(5):948-953
A method based on ICP collision-cell MS detection in capillary HPLC was developed to gain an insight into the purity and identity of selenium-containing proteins separated by 1-D and 2-D electrophoresis. The bands and spots obtained after the separation of water-soluble proteins in selenized yeast were digested with trypsin prior to chromatography. Selenium could be detected down to the subpicogram level. The method, assisted by information obtained by MALDI TOF MS on the 5000 Da cut-off fraction, permitted the purity of bands and spots to be estimated and the efficiency of tryptic digestion and the quantity of selenium present in individual peptides to be evaluated. Owing to the high sensitivity and the lack of matrix suppression effects, the method provided chromatograms with signal-to-noise ratios of 10–1000 in conditions where the common ES Q–TOF MS detection failed.
相似文献
17.
Hoffmann C Schmitt K Brandenburg A Hartmann S 《Analytical and bioanalytical chemistry》2007,387(5):1921-1932
The concentration of a recombinantly expressed protein has to be monitored to select optimal expression conditions throughout
the protein production process. Today this is usually achieved semiquantitatively with sodium dodecyl sulfate polyacrylamide
gel electrophoresis/western blotting or with ELISAs, which are time- and labor-intensive methods. In this paper the applicability
of a label-free sensor system based on a Young interferometer is presented as an alternative for the monitoring of recombinant
protein production. Once a protein is successfully produced, the interferometric biosensor allows any protein–protein interaction
to be characterized in a label-free manner. This is demonstrated with an antibody/antigen pair, where the antibody is directed
against a four-amino-acid tag used for protein expression analysis as well as purification during recombinant protein production.
Label-free detection of the tagged protein is shown both in buffer and in bacterial cell lysate as a sample matrix. The system
exhibiting a low limit of detection, low drift and reliable operation is compared with a commercial surface plasmon resonance
sensor and a competitive ELISA.
Figure 1 Waveguide sensor chip; grating (green) illuminated by a red light source. Image courtesy of Unaxis Optics
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
18.
Baek TJ Park PY Han KN Kwon HT Seong GH 《Analytical and bioanalytical chemistry》2008,390(5):1373-1378
We describe a DNA microarray system using a bipolar integrated circuit photodiode array (PDA) chip as a new platform for DNA
analysis. The PDA chip comprises an 8 × 6 array of photodiodes each with a diameter of 600 μm. Each photodiode element acts
both as a support for an immobilizing probe DNA and as a two-dimensional photodetector. The usefulness of the PDA microarray
platform is demonstrated by the detection of high-risk subtypes of human papilloma virus (HPV). The polymerase chain reaction
(PCR)-amplified biotinylated HPV target DNA was hybridized with the immobilized probe DNA on the photodiode surface, and the
chip was incubated in an anti-biotin antibody-conjugated gold nanoparticle solution. The silver enhancement by the gold nanoparticles
bound to the biotin of the HPV target DNA precipitates silver metal particles at the chip surfaces, which block light irradiated
from above. The resulting drop in output voltage depends on the amount of target DNA present in the sample solution, which
allows the specific detection and the quantitative analysis of the complementary target DNA. The PDA chip showed high relative
signal ratios of HPV probe DNA hybridized with complementary target DNA, indicating an excellent capability in discriminating
HPV subtypes. The detection limit for the HPV target DNA analysis improved from 1.2 nM to 30 pM by changing the silver development
time from 5 to 10 min. Moreover, the enhanced silver development promoted by the gold nanoparticles could be applied to a
broader range of target DNA concentration by controlling the silver development time.
Figure An optical image of the PDA chip and target DNA detection through silver enhancement
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
With UV irradiation, Hg2+ in aqueous solution can be converted into Hg0 cold vapor by low molecular weight alcohols, aldehydes, or carboxylic acids, e.g., methanol, formaldehyde, acetaldehyde,
glycol, 1,2-propanediol, glycerol, acetic acid, oxalic acid, or malonic acid. It was found that the presence of nano-TiO2 more or less improved the efficiency of the photo-induced chemical/cold vapor generation (photo-CVG) with most of the organic
reductants. The nano-TiO2-enhanced photo-CVG systems can be coupled to various analytical atomic spectrometric techniques for the determination of
ultratrace mercury. In this work, we evaluated the application of this method to the atomic fluorescence spectrometric (AFS)
determination of mercury in cold vapor mode. Under the optimized experimental conditions, the instrumental limits of detection
(based on three times the standard deviation of 11 measurements of a blank solution) were around 0.02–0.04 μg L−1, with linear dynamic ranges up to 15 μg L−1. The interference of transition metals and the mechanism of the photo-CVG are briefly discussed. Real sample analysis using
the photo-CVG-AFS method revealed that it was promising for water and geological analysis of ultralow levels of mercury.
Image of the photo-CVG instrumentation showing the photoreactor inside the water cooling unit 相似文献