共查询到20条相似文献,搜索用时 46 毫秒
1.
This article describes the use of microfluidic paper-based analytical devices (μPADs) to perform quantitative chemical assays
with internal standards. MicroPADs are well-suited for colorimetric biochemical assays; however, errors can be introduced
from the background color of the paper due to batch difference and age, and from color measurement devices. To reduce errors
from these sources, a series of standard analyte solutions and the sample solution are assayed on a single device with multiple
detection zones simultaneously; an analyte concentration calibration curve can thus be established from the standards. Since
the μPAD design allows the colorimetric measurements of the standards and the sample to be conducted simultaneously and under
the same condition, errors from the above sources can be minimized. The analytical approach reported in this work shows that
μPADs can perform quantitative chemical analysis at very low cost.
相似文献
2.
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
3.
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
4.
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
5.
Ortega-Algar S Ramos-Martos N Molina-Díaz A 《Analytical and bioanalytical chemistry》2008,391(2):715-719
A single optosensing device based on lanthanide-sensitized luminescence was developed for determination of p-aminobenzoic acid (PABA). The method is based on the formation of a complex between PABA and Tb(III) immobilized on the solid
phase (QAE A-25 resin) placed inside the flow cell. NaCl (1 M) was used as carrier solution and HCl (0.05 M) as eluent. The
sample solutions of PABA (100 μL) containing Tb(III) and buffered at pH = 6.0 were injected into the carrier stream and the
luminescence was measured at λ
ex = 290 nm and λ
em = 546 nm. The method shows a linear range from 0.2 to 6.0 μg mL−1 with an RSD of 1.2% (n = 10) and a sampling frequency of 22 h−1. A remarkable characteristic of the method is its high selectivity which allows it to be satisfactorily applied to the analysis
of PABA in pharmaceutical samples without prior treatment.
Figure Typical emission bands of Tb(III) in a solid-phase PABA–Tb(III) luminescence spectrum 相似文献
6.
Schumann CA Dörrenhaus A Franzke J Lampen P Dittrich PS Manz A Roos PH 《Analytical and bioanalytical chemistry》2008,392(6):1159-1166
To understand molecular networking at the cellular level, analyses of processes and effects at the single-cell level are most
appropriate. Usual biochemical or molecular biological analyses are based on integrated signals of numerous cells which differ,
however, in their expression and activity profiles. Here we show that it is possible to determine different types of properties
of individual cells by means of a specifically designed microfluidic device. As part of investigations to characterize the
human urothelial cell line 5637 as a potential model system for studies of toxic and carcinogenic effects on urothelial cells,
we use this cell line to assign cytochrome P450 activity, and expression of the enzymes involved, to individual cells. It
is shown that the cell population is very heterogeneous with respect to the extent and kinetics of CYP1A1-dependent ethoxyresorufin
O-deethylase (EROD). This is also true for the cells’ CYP1A1 protein content. With some exceptions, the EROD activity largely
coincides with the presence of CYP1A1 protein in the cells. The results obtained with the microfluidic device are promising
and open up new perspectives with regard to multi-property determinations in individual cells and to studies focusing on the
biochemical and molecular heterogeneity of cells.
Figure Formation of fluorescent resorufin from ethoxyresorufin by cytochrome P450 activity in urothelial cells attached within the
chamber of a microfluidic device 相似文献
7.
Casas V Llompart M Garcia-Jares C Cela R Dagnac T 《Analytical and bioanalytical chemistry》2007,387(5):1841-1849
The aqueous instability of pyrethroids and other compounds usually found in commercial pesticide formulations has been demonstrated
in this work. Several types of sample treatment have been studied to avoid analyte losses during sample manipulation and storage.
Analysis was performed by SPME–GC–MS. Addition of sodium thiosulfate to tap water prevented pyrethroid degradation as a result
of oxidation by free chlorine. The amount added was optimized to minimize the effect of the salt on the analytical results.
Analysis of samples that had been stored at 4 °C for several days revealed loss of some of the pyrethroids in the first period
of storage. The effect of freezing the samples was studied and it was confirmed that samples could be stabilized for at least
one week by freezing. Finally, addition of a miscible organic solvent, for example acetone, led to improvement of the analytical
precision. The quality of the SPME–GC–MS method was studied. Linearity (R > 0.993), repeatability (RSD < 15%), and sensitivity
(detection limits between 0.9 and 35 pg mL−1) were good. When the procedure was applied to real samples including run off and waste water some of the target compounds
were identified and quantified.
相似文献
8.
Amatatongchai M Hofmann O Nacapricha D Chailapakul O deMello AJ 《Analytical and bioanalytical chemistry》2007,387(1):277-285
A microfluidic system incorporating chemiluminescence detection is reported as a new tool for measuring antioxidant capacity.
The detection is based on a peroxyoxalate chemiluminescence (PO-CL) assay with 9,10-bis-(phenylethynyl)anthracene (BPEA) as
the fluorescent probe and hydrogen peroxide as the oxidant. Antioxidant plugs injected into the hydrogen peroxide stream result
in inhibition of the CL emission which can be quantified and correlated with antioxidant capacity. The PO-CL assay is performed
in 800-μm-wide and 800-μm-deep microchannels on a poly(dimethylsiloxane) (PDMS) microchip. Controlled injection of the antioxidant
plugs is performed through an injection valve. Of the plant-food based antioxidants tested, β-carotene was found to be the
most efficient hydrogen peroxide scavenger (SA
HP of 3.27 × 10−3 μmol−1 L), followed by α-tocopherol (SA
HP of 2.36 × 10−3 μmol−1 L) and quercetin (SA
HP of 0.31 × 10−3 μmol−1 L). Although the method is inherently simple and rapid, excellent analytical performance is afforded in terms of sensitivity,
dynamic range, and precision, with RSD values typically below 1.5%. We expect our microfluidic devices to be used for in-the-field
antioxidant capacity screening of plant-sourced food and pharmaceutical supplements.
Figure Assembled PDMS microchip sandwiched between two glass plates with the top plate containing capillary reservoirs 相似文献
9.
Cordes DB Miller A Gamsey S Singaram B 《Analytical and bioanalytical chemistry》2007,387(8):2767-2773
The simultaneous use of several fluorescent reporter dyes in a multicomponent boronic acid-based glucose sensing system is
reported. In one application, two dyes with widely different emission wavelengths are used to report changes in glucose concentration.
A third glucose-insensitive dye was then added to act as a reference dye and provide for a ratiometric correction to the two
reporter dye signals. The inclusion of such a reference dye reduces errors arising from sources such as fluctuations in lamp
intensity and sample dilution.
The simultaneous use of multiple fluorescent reporter dyes 相似文献
10.
Direct methylation and solid-phase microextraction (SPME) were used as a sample preparation technique for classification of
bacteria based on fatty acid methyl ester (FAME) profiles. Methanolic tetramethylammonium hydroxide was applied as a dual-function
reagent to saponify and derivatize whole-cell bacterial fatty acids into FAMEs in one step, and SPME was used to extract the
bacterial FAMEs from the headspace. Compared with traditional alkaline saponification and sample preparation using liquid–liquid
extraction, the method presented in this work avoids using comparatively large amounts of inorganic and organic solvents and
greatly decreases the sample preparation time as well. Characteristic gas chromatography/mass spectrometry (GC/MS) of FAME
profiles was achieved for six bacterial species. The difference between Gram-positive and Gram-negative bacteria was clearly
visualized with the application of principal component analysis of the GC/MS data of bacterial FAMEs. A cross-validation study
using ten bootstrap Latin partitions and the fuzzy rule building expert system demonstrated 87 ± 3% correct classification
efficiency.
相似文献
11.
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
12.
Frank LA Borisova VV Markova SV Malikova NP Stepanyuk GA Vysotski ES 《Analytical and bioanalytical chemistry》2008,391(8):2891-2896
Two kinds of Ca2+-regulated photoprotein obelin with altered color of bioluminescence were obtained by active-center amino acid substitution.
The mutant W92F-H22E emits violet light (λmax = 390 nm) and the mutant Y139F emits greenish light (λ
max = 498 nm), with small spectral overlap, both display high activity and stability and thus may be used as reporters. For demonstration,
the mutants were applied in dual-color simultaneous immunoassay of two gonadotropic hormones—follicle-stimulating hormone
and luteinizing hormone. Bioluminescence of the reporters was simultaneously triggered by single injection of Ca2+ solution, divided using band-pass optical filters and measured with a two-channel photometer. The sensitivity of simultaneous
bioluminescence assay was close to that of a separate radioimmunoassay.
Figure Two kinds of Ca2+-regulated photoprotein obelin with altered color of bioluminescence were obtained and applied in dual-color simultaneous
immunoassay of two gonadotropic hormones. 相似文献
13.
Destandau E Lefèvre JP Chouai Fakhr Eddine A Desportes S Jullien MC Hierle R Leray I Valeur B Delaire JA 《Analytical and bioanalytical chemistry》2007,387(8):2627-2632
A microfabricated device has been developed for fluorimetric detection of potassium ions without previous separation. It is
based on use of a fluorescent molecular sensor, calix–bodipy, specially designed to be sensitive to and selective for the
target ion. The device is essentially made of a Y-shape microchannel moulded in PDMS fixed on a glass substrate. A passive
mixer is used for mixing the reactant and the analyte. The optical detection arrangement uses two optical fibres, one for
excitation by a light-emitting diode, the other for collection of the fluorescence. This system enabled the flow-injection
analysis of the concentration of potassium ions in aqueous solutions with a detection limit of 0.5 mmol L−1 and without interference with sodium ions. A calibration plot was constructed using potassium standard solutions in the range
0–16 mmol L−1, and was used for the determination of the potassium content of a pharmaceutical pill.
Figure Photography of the microfluidic channel showing the ridges in the PDMS substrate at the top of the channel 相似文献
14.
R. DellAnna P. Lazzeri M. Frisanco F. Monti F. Malvezzi Campeggi E. Gottardini M. Bersani 《Analytical and bioanalytical chemistry》2009,394(5):1443-1452
The discrimination and classification of allergy-relevant pollen was studied for the first time by mid-infrared Fourier transform
infrared (FT-IR) microspectroscopy together with unsupervised and supervised multivariate statistical methods. Pollen samples
of 11 different taxa were collected, whose outdoor air concentration during the flowering time is typically measured by aerobiological
monitoring networks. Unsupervised hierarchical cluster analysis provided valuable information about the reproducibility of
FT-IR spectra of the same taxon acquired either from one pollen grain in a 25 × 25 μm2 area or from a group of grains inside a 100 × 100 μm2 area. As regards the supervised learning method, best results were achieved using a K nearest neighbors classifier and the leave-one-out cross-validation procedure on the dataset composed of single pollen grain
spectra (overall accuracy 84%). FT-IR microspectroscopy is therefore a reliable method for discrimination and classification
of allergenic pollen. The limits of its practical application to the monitoring performed in the aerobiological stations were
also discussed.
Figure Traditional and innovative methods for the identification of airborne pollen grains 相似文献
15.
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
16.
Monterola MP Smith BW Omenetto N Winefordner JD 《Analytical and bioanalytical chemistry》2008,391(7):2617-2626
A simple, fast, reliable, sensitive and potentially portable explosive detection device was developed employing laser photofragmentation
(PF) followed by heterogeneous chemiluminescence (CL) detection. The PF process involves the release of NOx(x = 1,2) moieties from explosive compounds such as TNT, RDX, and PETN through a stepwise excitation–dissociation process using a 193 nm
ArF laser. The NOx(x = 1,2) produced upon PF is subsequently detected by its CL reaction with basic luminol solution. The intensity of the CL signal
was detected by a thermoelectrically cooled photomultiplier tube with high quantum efficiency and negligible dark current
counts. The system was able to detect trace amounts of explosives in various forms in real time under ambient conditions.
Detection limits of 3 ppbv for PETN, 2 ppbv for RDX, and 34 ppbv for TNT were obtained. It was also demonstrated that the
presence of PETN residue within the range of 61 to 186 ng/cm2 can be detected at a given signal-to-background ratio of 10 using a few microjoules of laser energy. The technique also demonstrated
its potential for the direct analysis of trace explosive in soil. An LOD range of 0.5–4.3 ppm for PETN was established, which
is comparable to currently available techniques.
Figure Photofragmentation–chemiluminescence detector 相似文献
17.
Ralf Bienert Franziska Emmerling Andreas F. Thünemann 《Analytical and bioanalytical chemistry》2009,395(6):1651-1660
The spherical gold nanoparticle reference materials RM 8011, RM 8012, and RM 8013, with a nominal radius of 5, 15, and 30 nm,
respectively, have been available since 2008 from NIST. These materials are recommended as standards for nanoparticle size
measurements and for the study of the biological effects of nanoparticles, e.g., in pre-clinical biomedical research. We report
on determination of the size distributions of these gold nanoparticles using different small-angle X-ray scattering (SAXS)
instruments. Measurements with a classical Kratky type SAXS instrument are compared with a synchrotron SAXS technique. Samples
were investigated in situ, positioned in capillaries and in levitated droplets. The number-weighted size distributions were
determined applying model scattering functions based on (a) Gaussian, (b) log-normal, and (c) Schulz distributions. The mean
radii are 4.36 ± 0.04 nm (RM 8011), 12.20 ± 0.03 nm (RM 8012), and 25.74 ± 0.27 nm (RM 8013). Low polydispersities, defined
as relative width of the distributions, were detected with values of 0.067 ± 0.006 (RM 8011), 0.103 ± 0.003, (RM 8012), and
0.10 ± 0.01 (RM 8013). The results are in agreement with integral values determined from classical evaluation procedures,
such as the radius of gyration (Guinier) and particle volume (Kratky). No indications of particle aggregation and particle
interactions—repulsive or attractive—were found. We recommend SAXS as a standard method for a fast and precise determination
of size distributions of nanoparticles.
相似文献
18.
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
19.
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
20.
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