Microchip capillary electrophoresis substrate used

Many of these microsystems have been described, but capillary electrophoresis (CE) microchips seem to be the most widely developed. The concept of p-TAS was proposed by Manz et al. in 1990 [1] and 2 years later, electrophoresis in planar chips was successfully integrated and its use demonstrated using silicon and glass substrates [2,3]. This area of miniaturised analysis systems has grown rapidly, as is shown in two complete revisions by Manz et al. [4,5], the first dealing with theory and technology and the second one with analytical standard operations and applications, and the development continues exponentially. 

One of the earliest efforts of qualitative measurement of a protein (human serum albumin) in a microchip-based device was based on bead agglutination in a microchamber (approximately lOjaL). Subsequently, several quantitative immunoassays have been performed using microchip electrophoretic systems that permit separation and quantitation of free- and bound-labeled antigens in competitive assays (see Chapter 5). Most are carried out in channels micro-machined into fused silica substrates. Early work on quantitative assays achieved measurement of cortisol in serum.The assay used cortisol labeled with fluorescein and an argon laser detector at 488 nm and required only 80 pL of a 40x dilution of serum as the sample. Other capillary electrophoresis-based assays for a variety of antibodies have also been developed that include immunoglobulins (IgG, IgA, and IgM), antibovine serum albumin, and antiestradiol. ... 

Finally, it is important to acquaint readers, particularly those more familiar with electrophoretic separations than materials characterization, with techniques that can be used to characterize different substrate materials and coatings. The direct analysis of the interior of capillaries is challenging so most of the methods discussed below are measured on a comparable flat surface. While it can be debated whether this approach is reasonable for traditional fused silica capillaries, the analogy between a flat surface of the material and the surface of the capillary in a microchip device is quite reasonable. The characterization methods that will be discussed here range from measurements of EOF to analysis of surface chemistry using X-ray spectroscopy techniques, with an emphasis on both how the measurement techniques are applied to materials used for electrophoresis and on how the results can be used to improve separation performance. 

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