Chip-Based Systems

Chip-based systems that employ microfluidics have become a popular research area and a number of systems are now available commercially that utilize electrophoresis-... 

Miniaturizing a conventional-flow screening system (macro-scale system) to a chip-based system comprises a number of changes, such as flow rates, reagent supply, and the material. While the conventional system with the open tubular reactors is restricted to polymer reactors, the choice of materials for the chip is... 

Recently, a lot of work in electrophoretic separation has focused on employing chip-based systems, which benefit from the enhancement of ef-... 

The so-called micro-total analytical systems (/tTAS) can integrate sample handling, separation, and detection on a single chip [9]. Postcapillary reaction detectors can be incorporated as well [10]. Fluorescence detection is the most common method employed for these chip-based systems. A commercial instrument (Agilent 2100 Bioanalyzer) is available for DNA and RNA separations on disposable chips using a diode laser for LIF detection. In research laboratories, polymerase chain reaction (PCR) has been integrated into a chip that provides size separation and LIF detection [11]. 

Chan SD, Luedke G, Valer M, Buhlmann C, Preckel T, Cytometric analysis of protein expression and apoptosis in human primary cells with a novel microfluidic chip-based system. Cytometry 2003 55A(2) 119-25. 

Laser-induced fluorescence detection is a logical choice for high-resolution SCCE when performed on microfluidic chip-based systems. High laser power can result in photobleaching, decreasing the analyte signal every time it passes through the beam. ... 

Chip-based systems Miniaturized systems Protein chip Protein profiling Proteomics... 

Buhlmann C, Valer M, Mueller O (2004) Combination of DNA laddering and annexin-V and caspase assays on one system - multiple apoptosis parameters analysis with a microfluidic chip-based system. Tissue Antigens 64 392-392... 

In addition to these various chemical treatment methods, a number of physical methods of cell disruption can be used in a chip-based system. These physical methods include osmotic shock, which occurs when cells are suspended in a hypotonic solution shearing and fracturing of cells walls and membranes using... 

Genomics will continue to grow and provide increasingly significant opportunities related to the health care industry. Some of the work in this field involves the creation of new medical devices for DNA analysis and chip based systems. As the genomes of animals are decoded and profiled, opportunities have opened for... 

Another technique that shows potential for use in the EDM assay arena is the nanoelectrospray technology. Nanoelectrospray has been available for many years but has recently become available in a convenient chip-based system that can be used for both quantitative and qualitative applications (Dethy et al., 2003 Ackermann and Dethy, 2005 Wickremsinhe et al., 2005, 2006). The main advantage of this technique is that it is fairly easy to implement (it can be interfaced directly to many triple quadrupole MS systems) and it provides a fast assay time (about 20—30 s/sample). Van Pelt et al. (2003) described the use of the nanoelectrospray system for the analysis of Caco-2 samples. More reeently, Balimane et al. (2005) demonstrated that a chip-based nanoelectrospray system could be used to assay PAMPA samples in a high-throughput maimer. In this report, the samples for 10 test compounds were assayed by HPLC UV or nanoelectrospray and the permeability results from the two assays were found to be similar for this test set. 

Conventional chromatographic or capillary electrophoretic devices are based on analyte detection by absorbance, for example, of ultraviolet (UV) light. However, in chip-based systems absorbance measurements are the exception as detection cells have to be developed leading to an extension of the path-length of the transmitted fight. 

Table 2 BioMEMS applications using pSi as part of a chip-based system...

Besides these aforementioned applications, porous silicon can also be used as part of a chip-based system, providing different functionalities. Table 2 presents those BioMEMS applications, including microfluidic applications (Abgrall and Gue 2007). 

The rapidly developing field of porous silicon-based biosensors that utilize optical transduction is comprehensively reviewed by distinguishing the differing strategies for small- and moderate-size biomolecular analytes and the challenges with analysis of complex biofluids. A number of topics are identified for future research that should lead to one-shot disposable chip-based systems becoming commercially avialable. 

Several research groups have reported ways to preconcentrate samples in Lab-on-a-Chip devices. While most on-chip preconcentration approaches evolve from conventional capillary electrophoresis and chromatographic column techniques, these preconcentration techniques play an increasingly important role in chip-based system. The basic preconcentration strategies applied on microfluidic devices can be classified into three large categories electrokinetic preconcentration, chromatographic preconcentration and membrane preconcentration. 

Figure 16.12 Representation of the (a) scheme for instrumental controlling. Reproduced with permission from [190]. Copyright 2010 WILEY-VCH Verlag CmbH Co. KCaA, Weinheim and [187] 2012 WILEY-VCH Verlag CmbH Co. (bj the main unit of a portable chip-based system coupled with amperometric detection. Reproduced with permission from Ref [191]. Copyright 2010 WILEY-VCH Verlag CmbH Co. KCaA, Weinheim...

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