Immunochromatographic system

A noncompetitive method in which the Ag-Ab-label is detected in the immunochromatographic system without performing any desorption step has been carried out in a microchip format [53], The Ag to be determined is adsorbed onto beads that are introduced into the microchannels, followed by Ab labeled with colloidal gold. Detection of the Ag-Ab-label takes place inside the channel. 

One difference between immunochromatographic systems and immuno-capillary electrophoretic systems that is inherent in the methods themselves and affects sensitivity is the concentration that takes place in the first group of methods. As an example, in the determination of anti-BSA using labeled BSA, the chromatographic method provided concentration sensitivity about 100-fold compared with the electrophoretic one the mass sensitivity is similar for both methods [104]. 

An immunochromatographic system for simple and convenient DiAcSpm measurement was recently developed for personal use (Moriya et al. 2014). DiAcSpm is more sensitive than most conventional tumor markers in detecting early cancers. 

In addition to the immunochromatographic assays, another system used by the Allies during Desert Storm for the detection of biological warfare agents was the Light Addressable Potentiometric System (LAPS) produced by Molecular Devices (Sunnyvale, CA)19. The LAPS detected toxins and... 

The first immunoassay performed in a capillary driven system was reported in 1978 [67]. Based on this technique, the commonly known over-the-counter pregnancy test was introduced into the market in the middle of the 80 s. Today, this microfluidic platform is commonly designated as a lateral flow test (LAT) [14]. Other terms are test strip , immunochromatographic strip , immunocapillary tests or sol particle immunoassay (SPIA) [68]. Astonishingly, hardly any publications from a microfluidic point of view or in terns of material classification exist, and apparently many company secrets are kept unpublished [69]. 

Lateral-flow immunoassays (LFTAs), also known as immunochromatographic test strips or dipsticks, are a form of rapid and portable immunoassay in which the test sample extract flows along a solid substrate via capillary action. The dipstick system is simple operationally, whereas the technology behind it is advanced and subtle. 

Several reviews devoted to or including immunoassays performed in HPLC or CE systems have been published [4-12]. These methods have been used for analysis of small and large molecules. Besides the application to detect the presence and concentration of an analyte in a sample, immunochromatographic and immunocapillary electrophoretic systems have a wide application in the determination of antibody-antigen binding constants. 

This chapter is focused on methods that use antibody-antigen interactions in HPLC or CE systems for the detection of proteins. Although immunoassays performed in LC and CE systems are similar, they vary in many practical aspects. For this reason, immunochromatographic and immunocapillary electrophoretic detection will be described separately. 

RGURE 5 Scheme for performing immunochromatographic analysis in three-column systems including two immunorecognition steps. Symbols as in Fig. 2. ... 

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