Lab-on-a-chip technologies

This series will cover the wide ranging areas of Nanoscience and Nanotechnology. In particular, the series will provide a comprehensive source of information on research associated with nanostructured materials and miniaturised lab on a chip technologies. 

Recently, the miniaturization procedures of bioanalytical studies have become an important research area with particular focus on modem concept of lab-on-a-chip technology [48], with a reduction in manufacturing costs, easy transport, minimal space and minimal maintenance requirements (and costs) in the laboratory and in the fields, even if this progress require a long design and implementation time, non-stable robotic operation, and limited error recovery abilities. 

In the last case, the use of standard silicon microelectronics technology allow the possibility for integration of optical, fluidics and electrical functions on a single optical sensing circuit leading to a complete lab-on-a-chip technological solution. With this sensor a detection limit in the femtomole range is achievable in a direct format. 

Currently, after each step in the synthesis process, a sample is analyzed to approve or reject the operation. Not only is this inefficient for the industry in general, this is also a stumbling block for a rapid scale-up. Controls and measurements of the process need to be accomplished in situ, which is again an issue that requires the chemists and chemical engineers to work together toward a solution. It may, in fact, involve lab-on-a-chip technologies and microreactors that were presented by other speakers in this workshop. 

S. Joo, M. Duhon, M. Heller, B. Wallace, and X. Xu, Dielectrophoretic Cell Separation and Gene Expression Profiling on Microelectronic Chip Arrays, Anal. Chem 2002, 74, 3362 D. Figeys and D. Pinto, Lab-on-a-Chip A Revolution in Biological and Medical Sciences, Anal. Chem 2000, 72, 330A C. H. Legge, Chemistry Under the Microscope—Lab-on-a-Chip Technologies, ... 

First, a general method of transformation of the expression plasmid into E. coli will be described, as well as appropriate conditions for growth and induction of the expression cultures. Then, the 96-well protein purification method is detailed. Last, analysis of the purified proteins is described using both lab-on-a-chip technology and traditional sodium dodecyl sulfide (SDS)-polyacryla-mide gel electrophoresis (PAGE). 

Craighead, H. G. (2006). Future lab-on-a-chip technologies for interrogating individual molecules. Nature 442, 387-393. 

Finally, it is anticipated that the trend toward miniaturizahon will conhnue and that applications that truly beneht from nanotechnology and microlluidics will become apparent over hme. While much attenhon has recently been given to Lab-on-a-Chip technology, MS has lagged behind other forms of detection. Current advances toward the interface between ESI and microchip technology suggest that MS applicahons will soon be more prevalent [133]. 

Several companies are developing analytical instruments and information systems based on the concept of lab-on-a-chip technology (458-463). The chip-... 

The system developed in this work establish a general electrochemical detection methodology that can be applied to a variety of immunosystems and DNA detection systems, including lab-on-a-chip technology, with special interest for further applications in clinical analysis, food quality and safety as well as other industrial applications. 

In the development of lab-on-a-chip technology, a key is to develop the ability to pump the liquids and transport sample/reagent molecules as well as biological cells in a microchannel network. This can be achieved by using the electroosmotic flow and electrophoresis. Mixing of different solutions and dispensing a specified amount of one solution from one microchannel into another microchannel are important to many microfluidic chips. There are extensive research works done in these areas [1]. Furthermore, precise control of temperature is often critical to on-chip biochemical reactions. In the following the PCR lab-on-a-chip, flow cytometer lab-on-a-chip and immunoassay lab-on-a-chip will be reviewed. 

However, the flow cytometers are bulky and expansive, and are available only in large reference laboratories. In addition, the required sample volumes are quite large, usually in the 100 pL range. Many clinical applications require frequent blood tests to monitor patients status and the therapy effectiveness. It is highly desirable to use only small amount of blood samples Ifom patients for each test. Furthermore, it is highly desirable to have affordable and portable flow cytometry instruments for field applications, point-of-care applications and applications in resource-limited locations. To overcome these drawbacks and to meet the increasing needs for versatile cellular analyses, efforts have been made recently to apply microfluidics and lab-on-a-chip technologies to flow cytometric analysis of cells. 

An ideal on-site detection system would be inexpensive, sensitive, fully automated, reliable, multiplex sample handling, and detect a broad range of explosives. The advent of microfluidic lab-on-a-chip technology might offer such a detection system. Microfluidic capillary electrophoresis chips have been utilized for the detection of nitroaromatics such as TNT, DNT, NT, and DNB [9-12]. Due to the good redox properties of nitroaromatics and the inherent suitability for miniaturization, most of the microfluidic methods so far used electrochemical methods for detection. The individual components of nitroaromatics can be detected in the capillary electrophoresis chips (analyte-specific) unlike the colorimetric methods (class-specific) where nitroaromatics are detected broadly. 

Fig. 4.4. Diagnostic test based on microfluidic lab-on-a-chip technology (From [7] Copyright 2006 Nature Publishing Group)...

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