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At least 199 records · Page 11Linked to original sources
PubMed2005

Clinical analysis by microchip capillary electrophoresis.

Clinical analysis often requires rapid, automated, and high-throughput analytical systems. Microchip capillary electrophoresis (CE) has the potential to achieve very rapid analysis (typically seconds), easy integration of multiple analytical steps, and parallel operation. Although it is currently still in an early stage of development, there are already many reports in the literature describing the applications of microchip CE in clinical analysis. At the same time, more fully automated and higher throughput commercial instruments for microchip CE are becoming available and are expected to further enhance the development of applications of microchip CE in routine clinical testing. To put into perspective its potential, we briefly compare microchip CE with conventional CE and review developments in this technique that may be useful in diagnosis of major diseases.

Biomarkers↗
PubMed2006

Rapid DNA amplification in glass microdevices.

The polymerase chain reaction (PCR) for amplification of DNA has become a very useful tool in scientific research and analytical laboratories, yet conventional techniques are time-consuming, and the reagents are expensive. Miniaturization of this technique has the potential to drastically reduce amplification time and reagent consumption while simultaneously improving the efficiency of the reaction. Increasing the surface area-to-volume ratio using microfluidic reaction chambers allows homogeneous solution temperatures to be achieved much more rapidly than in conventional heating blocks. Employing infrared radiation to selectively heat the reaction solution can additionally reduce the time and energy needed for thermocycling; the reaction container is not heated and can even serve as a heat sink for enhancement of cooling. Microchip systems also provide the potential for fabrication of structures for additional processing steps directly in line with the PCR chamber. Not only can amplification be integrated with product separation and analysis, but sample preparation steps can also be incorporated prior to amplification. The ultimate goal is a miniature total-analysis-system with seamlessly coupled sample-in/answer-out capabilities that consumes very low volumes of reagents and drastically reduces the time for analysis. This chapter will focus on the materials and methods involved in simple straight-channel microchip PCR on glass substrates using non-contact thermocycling.

Bacterial Proteins↗
PubMed2004

Proteomics-on-a-chip: the challenge to couple lab-on-a-chip unit operations.

This review describes a vision of a proteomics-on-a-chip device to separate, detect and identify the proteome. It guides the reader towards a development strategy, avoiding some of the pitfalls. It also describes the current state-of-the-art developments in proteomic analysis including available technologies, current market issues, the elements of an envisaged proteomics-on-a-chip device, the required microfabrication processes and the integration of the elements into one device. Address-flow microfluidics is a tool for connecting separation and detection platforms. The final section contains an expert opinion on the recommended development strategies, benefits of proteomics-on-a-chip in the life sciences and the anticipated market.

Drug Design↗
PubMed2005

Macromolecular crystallization with microfluidic free-interface diffusion.

Fluidigm Corp. released the Topaz 1.96 and 4.96 crystallization chips in the fall of 2004. Topaz 1.96 and 4.96 are the latest evolution of Fluidigm's microfluidics crystallization technologies that enable ultra-low-volume rapid screening for macromolecular crystallization. Topaz 1.96 and 4.96 are similar to each other but represent a major redesign of the Topaz system and have substantially improved ease of automation and ease of use, improved efficiency and even further reduced the amount of material needed. With the release of the new Topaz system, Fluidigm continues to set the standard in low-volume crystallization screening, which is having an increasing impact in the field of structural genomics and more generally in structural biology. It is likely that further optimization and increased utility of the Topaz crystallization system will emerge. It is also probable that further innovation and the emergence of competing technologies will be seen.

Crystallization↗
PubMed2005

Interaction analysis of the carcinoembryonic antigen (CEA) with its monoclonal antibody immobilized on a gold surface using Fourier transform infrared reflection-absorption spectroscopy (FT-IR RAS).

A monoclonal antibody for the carcinoembryonic antigen (CEA) was immobilized on a gold chip surface covered by a self-assembled monolayer of 11-mercaptoundecanoic acid. Upon the addition of CEA, a Fourier transform infrared reflection-absorption spectroscopy (FT-IR RAS) measurement showed an increased absorption at around 1500 - 1700 cm(-1), corresponding to its amide structures. Another addition of CEA polyclonal antibody on this chip caused a further increase of the absorption in this region only after a treatment with CEA. This result shows that an antibody-fixed gold surface coupled with an FT-IR RAS measurement provides a new tool for detecting the antibody-antigen interaction.

Antibodies, Monoclonal↗
PubMed2005

Rapid separation of microorganisms by quartz microchip capillary electrophoresis.

We developed and optimized a system coupling microchip capillary electrophoresis (MCE) and laser-induced fluorescence (LIF) detection for the analysis of microorganisms. The MCE-LIF system successfully separated pure cultures of lactic acid bacteria and Saccharomyces cerevisiae within 200 s. The results indicate that the MCE system can be conveniently used for the rapid and highly sensitive detection of microorganisms. Thus, MCE can provide a cheap and simple method for the on-line detection of microbial contamination.

Bacteria↗
PubMed2004

Microchip electrophoresis with hydrodynamic injection and waste-removing function for quantitative analysis.

Quantitative analysis is problematic for microchip electrophoresis for several reasons including chip-to-chip variation, discontinuous sample re-loading, channel reconditioning, and electrokinetic injection bias. In this study, the capability for quantitative analysis on a flow-through based microchip electrophoresis, which provides continuous sample re-loading, channel washing, reconditioning and hydrodynamic injection as well as waste removing is demonstrated to be more quantifiable and more reproducible compared to manual electrokinetic injection method. Using the flow-through microchip with waste-removing function, FITC-labeled estrogen or Rhodamine B could be continuously analyzed without significant changes (R.S.D. < 6.6%) in signal intensity for over 3 h, which is sufficient for a complete set of quantitative analysis. With the use of a phosphorylated kinase substrate as the model, a calibration curve for quantitative analysis of phosphopeptides were constructed and results indicate that both R2 value of the linearity and R.S.D. values of the peak intensity were around 0.9961 and 3.16%, respectively, without the use of an internal standard. These values were slightly improved to be around 0.9986 and 2.27%, respectively, with the use of a non-phosphopeptide counterpart as the internal standard. The potential of this flow-through device for the development of a kinase phosphorylation assay based on the quantitative method was also briefly discussed.

Amino Acid Sequence↗
PubMed2004

Size-based continuous-flow directional control of DNA with a nano-pillar anisotropic array.

A size-based pre-fractionation chip applicable for enrichment of macromolecules in biological samples is proposed. In this chip, a fractionation unit with a nano-pillar anisotropic array, which functions as sieve meshes, is installed at a bi-forked junction. The mesh sizes are close to the diameters of macromolecules and vary according to the direction to the main and branch exit channels. This fractionation unit provides continuous-flow fractionation without both the dilution of samples and the limitations with the sample loading volume. Additionally, the small channel-volume, which is characteristic of chip-based systems, can reduce sample loss. Using nanometer-scale fabrication technology, we fabricated the chips and demonstrated the flow direction control of DNA molecules.

DNA↗
PubMed2004

Simultaneous determination of nitrate and nitrite in biological fluids by capillary electrophoresis and preliminary study on their determination by microchip capillary electrophoresis.

In order to develop a highly sensitive and high-throughput screening method for nitrogen monoxide metabolites in biological fluids, we have investigated the simultaneous determination of nitrite and nitrate, using capillary electrophoresis and microchip capillary electrophoresis. In capillary zone electrophoresis, a running buffer based on human serum components with high ionic strength has been developed for the determination of nitrite and nitrate in human serum and human saliva. We obtained successful separation of nitrite and nitrate in the serum and the saliva within 7 min under optimum analytical conditions. Linear calibration curves for nitrite and nitrate for both peak height and area were obtained by a standard addition method. The limits of detection obtained at a signal-to-noise ratio (S/N) of 3 for nitrite and nitrate in the serum were 2.6 and 1.5 microM, respectively. The values of the relative standard deviation of peak height for the serum with 9.2 microM nitrite and 20.9 microM nitrate were 5.7 and 4.1%, respectively. For on-site analysis with high-throughput screening, a microchip capillary electrophoresis method using a microchip made of quartz with a UV detector was developed. In this high-throughput format, using a running buffer with an electroosmotic flow modifier, the peaks of nitrite and nitrate in an artificial serum sample were obtained within 8 s. In high-resolution mode, using the buffer without electroosmotic flow modifier, the separation of nitrite and nitrate was obtained within 15 s. In high-resolution mode, using an artificial serum sample with 50 microM NO2- and 50 microM NO3-, the limits of detection (S/N = 3) of 41 microM for NO2- and 26 microM for NO3- were obtained. The method was applied to human serum and saliva. We obtained peaks due to nitrite and nitrate in 10-fold diluted saliva.

Electrochemistry↗