共查询到20条相似文献,搜索用时 31 毫秒
1.
Bo Xu Xiaojun Feng Youzhi Xu Wei Du Qingming Luo Bi-Feng Liu 《Analytical and bioanalytical chemistry》2009,394(7):1911-1917
Analysis of complex biological samples requires the use of high-throughput analytical tools. In this work, a microfluidic
two-dimensional electrophoresis system was developed with mercury-lamp-induced fluorescence detection. Mixtures of 20 standard
amino acids were used to evaluate the separation performance of the system. After fluorescent labeling with fluorescein isothiocyanate,
mixtures of amino acids were separated by micellar electrokinetic chromatography in the first dimension and by capillary zone
electrophoresis in the second. A double electrokinetic valve system was employed for the sample injection and the switching
between separation channels. Under the optimized conditions, 20 standard amino acids were effectively separated within 20 min
with high resolution and repeatability. Quantitative analysis revealed linear dynamic ranges of over three orders of magnitudes
with detection limits at micromolar range. To further evaluate the reliability of the system, quantitative analysis of a commercial
nutrition supplement liquid was successfully demonstrated.
Figure 相似文献
2.
A novel method for the future development of label-free DNA sensors is proposed here. The approach is based on the displacement
of a labelled suboptimum mutated oligonucleotide hybridised with the immobilised biotin-capture probe. The target fully complementary
to the biotin-capture probe can displace the labelled oligonucleotide causing a subsequent decrease of the signal that verifies
the presence of the target. The decrease of signal was demonstrated to be proportional to the target concentration. A study
of the hybridisation of mutated and complementary labelled oligonucleotides with an immobilised biotin-capture probe was carried
out. Different kinetic and thermodynamic behaviour was observed for heterogeneous hybridisation of biotin-capture probe with
complementary or suboptimum oligonucleotides. The displacement method evaluated colourimetrically achieved the objective of
decreasing the response time from 1 h for direct hybridisation of 19-mer oligonucleotides in the direct enzyme-linked oligonucleotide
assay (ELONA) to 5 min in the case of displacement detection in the micromolar concentration range.
Figure The detection system is based on the displacement of suboptimum HRP-labelled mutated oligonucleotide by the fully complementary
target 相似文献
3.
A miniaturized fluorescence detector utilizing a three-dimensional windowless flow cell has been constructed and evaluated. The inlet and outlet liquid channels are collinear and are located in the same plane as the excitation paths, while the optical fiber used to collect the emission light is perpendicular to this plane. The straightforward arrangement of the flow path minimizes band dispersion and eliminates bubble formation or accumulation inside the cell. The use of high-brightness light-emitting diodes (LEDs) as the excitation source and a miniaturized metal package photomultiplier tube (PMT) results in a compact and sensitive fluorescence detector. The detection limit obtained from the system for fluorescein isothiocyanate (FITC) in flow injection mode is 2.6 nmol/L. The analysis of riboflavin and FITC by packed capillary liquid chromatography is demonstrated.
相似文献
4.
Stratis-Cullum DN Griffin GD Mobley J Vo-Dinh T 《Analytical and bioanalytical chemistry》2008,391(5):1655-1660
This paper reports the first intensified biochip system for chemiluminescence detection and the feasibility of using this
system for the analysis of biological warfare agents is demonstrated. An enzyme-linked immunosorbent assay targeting Bacillus globigii spores, a surrogate species for Bacillus anthracis, using a chemiluminescent alkaline phosphatase substrate is combined with a compact intensified biochip detection system.
The enzymatic amplification was found to be an attractive method for detection of low spore concentrations when combined with
the intensified biochip device. This system was capable of detecting approximately 1 × 105
Bacillus globigii spores. Moreover, the chemiluminescence method, combined with the self-contained biochip design, allows for a simple, compact
system that does not require laser excitation and is readily adaptable to field use.
Figure Schematic diagram of the miniature biochip detection system 相似文献
5.
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
6.
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
7.
Laser-induced breakdown spectroscopy (LIBS) in liquids using a double-pulse Q-switched Nd:YAG laser system has provided reliable
results that give trace detection limits in water. Resonant laser excitation has been added to enhance detection sensitivity.
A primary laser pulse (at 532 nm), transmitted via an optical fiber, induces a cavitation bubble and shockwave at a target
immersed in a 10 mg l−1–100 mg l−1 indium (In) water suspension. The low-pressure rear of the shockwave induces bubble expansion and a resulting reduction in
cavity pressure as it extends away from the target. Shortly before the maximum diameter is expected, a secondary laser pulse
(also at 532 nm) is fed into the bubble in order to reduce quenching processes. The plasma field generated is then resonantly
excited by a fiber-guided dye laser beam to increase detection selectivity. The resulting resonance fluorescence emission
is optically detected and processed by an intensified optical multichannel analyzer system.
相似文献
8.
Aristidis E. Niotis Christos Mastichiadis Panagiota S. Petrou Ion Christofidis Athanasia Siafaka-Kapadai Konstantinos Misiakos Sotirios E. Kakabakos 《Analytical and bioanalytical chemistry》2009,393(3):1081-1086
An optical capillary waveguide fluoroimmunosensor based on glass capillaries internally coated with an ultrathin poly(dimethylsiloxane)
(PDMS) film is presented. The evaluation of the capillaries developed was done in comparison with aminosilanized [3-(aminopropyl)triethoxysilane,
APTES] glass and poly(methylpentene) (PMP) capillaries by immobilizing rabbit γ-globulins on the internal capillary wall.
Following reaction with (R)-phycoerythrin-labelled antibody, the capillary was scanned with a laser beam and the fluorescence waveguided through the
capillary wall was detected by a photomultiplier placed at one of its ends. The capillaries developed provided considerably
improved protein coating homogeneity (intracapillary coefficients of variation 2.9–6.6%) and repeatability (intercapillary
coefficients of variation 2.1–5.0%) compared with APTES-treated ones (7.9–13.4 and 8.5–15.2%, respectively). With use of these
capillaries in a sandwich-type immunosensor for the determination of rabbit γ-globulins, the assay detection limit was improved
eightfold (4.4 ng/mL) compared with that obtained using PMP capillaries (35.3 ng/mL), whereas the assay repeatability was
improved threefold (intra-assay coefficients of variation 5.9–13.1%) compared with APTES-treated capillaries (15.6–36%).
Optoelectronic set-up used to scan the capillaries (left) and representative fluorescence scannings of dual-band poly(methylpentene)
(PMP), PDMS-modified glass and APTES treated glass capillaries 相似文献
9.
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
10.
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
11.
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
12.
Henares TG Mizutani F Sekizawa R Hisamoto H 《Analytical and bioanalytical chemistry》2008,391(7):2507-2512
Single-drop analysis of two different real sample solutions (2 μL) while simultaneously monitoring the activity of two sets
of ten different proteases on a single microfluidic device is presented. The device, called a capillary-assembled microchip
(CAs-CHIP), is fabricated by embedding square glass sensing capillaries (reagent-release capillaries, RRC) in the polydimethylsiloxane
(PDMS) lattice microchannel, and used for that purpose. First, the performance reliability was evaluated by measuring the
fluorescence response of twenty caspase-3-sensing capillaries on a single CAs-CHIP, and a relative standard deviation of 1.5–8.2
(% RSD, n = 5 or 10) was obtained. This suggests that precise multiplexed protease-activity sensing is possible by using a single CAs-CHIP
with multiple RRCs embedded. Then, using a single CAs-CHIP, real sample analysis of the activity of ten different caspases/proteases
in cervical cancer (HeLa) cell lysate treated and untreated with the cell-death-inducer drug, doxorubicin, was simultaneously
carried out, and a significant difference in enzyme activity between these two samples was observed. These results suggested
the usefulness of the CAs-CHIP in the field of drug discovery.
Figure Single drop analysis of two real sample solutions including various different proteases using a single microfluidic device
was achieved 相似文献
13.
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
14.
This technical note reports on a new procedure to on-column-label organelles sampled from a tissue cross section into a fused
silica capillary. These organelles are then analyzed by capillary electrophoresis with postcolumn laser-induced fluorescence
detection. In this procedure, the fluorescent label does not come in contact with the tissue, which facilitates visualization
of the sampled tissue cross section. In addition, on-column labeling allows for better control of the reaction time and fluorescent
label concentrations. As a proof-of-principle, we show results of mitochondria from rat gastrocnemius muscle cross sections
that were on-column-labeled with 10-N-nonyl acridine orange (NAO), a mitochondrion-specific probe, and compare them with results for NAO in-tissue labeling of
the same tissue. The new organelle labeling procedure reported here may easily be extended to the analysis of individual organelles
in other biological samples and may become a valuable tool in studies investigating the role of mitochondria in muscle aging
and exercise physiology.
相似文献
15.
Lapainis T Scanlan C Rubakhin SS Sweedler JV 《Analytical and bioanalytical chemistry》2007,387(1):97-105
A laser-induced native fluorescence detection system optimized for analysis of indolamines and catecholamines by capillary
electrophoresis is described. A hollow-cathode metal vapor laser emitting at 224 nm is used for fluorescence excitation, and
the emitted fluorescence is spectrally distributed by a series of dichroic beam-splitters into three wavelength channels:
250–310 nm, 310–400 nm, and >400 nm. A separate photomultiplier tube is used for detection of the fluorescence in each of
the three wavelength ranges. The instrument provides more information than a single-channel system, without the complexity
associfated with a spectrograph/charge-coupled device-based detector. With this instrument, analytes can be separated and
identified not only on the basis of their electrophoretic migration time but also on the basis of their multichannel signature,
which consists of the ratios of relative fluorescence intensities detected in each wavelength channel. The 224-nm excitation
channel resulted in a detection limit of 40 nmol L−1 for dopamine. The utility of this instrument for single-cell analysis was demonstrated by the detection and identification
of the neurotransmitters in serotonergic LPeD1 and dopaminergic RPeD1 neurons, isolated from the central nervous system of
the well-established neurobiological model Lymnaea stagnalis. Not only can this system detect neurotransmitters in these individual neurons with S/N>50, but analyte identity is confirmed on the basis of spectral characteristics.
Lapainis and Scanlan contributed equally to this work. 相似文献
16.
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
17.
Fast and sensitive DNA analysis using changes in the FRET signals of molecular beacons in a PDMS microfluidic channel 总被引:3,自引:0,他引:3
Jung J Chen L Lee S Kim S Seong GH Choo J Lee EK Oh CH Lee S 《Analytical and bioanalytical chemistry》2007,387(8):2609-2615
A new DNA hybridization analytical method using a microfluidic channel and a molecular beacon-based probe (MB-probe) is described.
A stem-loop DNA oligonucleotide labeled with two fluorophores at the 5′ and 3′ termini (a donor dye, TET, and an acceptor
dye, TAMRA, respectively) was used to carry out a fast and sensitive DNA analysis. The MB-probe utilized the specificity and
selectivity of the DNA hairpin-type probe DNA to detect a specific target DNA of interest. The quenching of the fluorescence
resonance energy transfer (FRET) signal between the two fluorophores, caused by the sequence-specific hybridization of the
MB-probe and the target DNA, was used to detect a DNA hybridization reaction in a poly(dimethylsiloxane) (PDMS) microfluidic
channel. The azoospermia gene, DYS 209, was used as the target DNA to demonstrate the applicability of the method. A simple
syringe pumping system was used for quick and accurate analysis. The laminar flow along the channel could be easily controlled
by the 3-D channel structure and flow speed. By injecting the MB-probe and target DNA solutions into a zigzag-shaped PDMS
microfluidic channel, it was possible to detect their sequence-specific hybridization. Surface-enhanced Raman spectroscopy
(SERS) was also used to provide complementary evidence of the DNA hybridization. Our data show that this technique is a promising
real-time detection method for label-free DNA targets in the solution phase.
Figure FRET-based DNA hybridization detection using a molecular beacon in a zigzag-shaped PDMS microfluidic channel 相似文献
18.
Bendrysheva SN Proskurnin MA Pyell U Faubel W 《Analytical and bioanalytical chemistry》2006,385(8):1492-1503
It is shown that organo-aqueous separation buffers show much promise when used in capillary electrophoresis separations with
photothermal (thermal lens) detection systems. Acetonitrile–water and methanol–water mixtures were selected, as conventionally
used in capillary electrophoresis. It is shown that, despite more sophisticated experimental conditions (significant heat
outflow from the capillary body) and peak detection, the theoretical ratio of the thermal lens signal for a binary mixture
to the thermal lens signal for an aqueous solution (or the corresponding ratio obtained experimentally under bulk batch conditions)
can be used to predict the sensitivity of thermal lens detection in capillary electrophoresis. The limits of detection for
2-, 3-, and 4-nitrophenols selected as model compounds in 70% v/v acetonitrile separation buffers are 1×10−6 M, 1×10−6 M and 3×10−7 M, respectively, and are therefore decreased by a factor of six compared to thermal lens detection in aqueous separation
buffers. The overall increase in the thermal lens detection sensitivity in a 100% ACN buffer is a factor of 13.
相似文献
19.
Digital bioanalysis 总被引:3,自引:1,他引:2
Digital microfluidics has recently emerged as a new paradigm in the world of lab-on-a-chip technology. A wide variety of bioanalyses
have been successfully implemented in this format. This paper reviews the various techniques that have been adapted to digital
microfluidic systems, and the current state of the field.
Figure A multiplexed digital microfluidic device. Six analytical platforms are wired in series, allowing multiple independent analyses
to be performed simultaneously from a single set of controls. 相似文献
20.
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