Capillary electrophoresis for immunoassays

Chiem, N., Harrison, D.J., Microchip-based capillary electrophoresis for immunoassays analysis of monoclonal antibodies and theophylline. Anal. Chem. 1997, 69, 373-378. 

Cheng SB, Skinner CD, Taylor J, Attiya S, Lee WE, Picelli G, et al. Development of a multichannel microfluidic analysis system employing afiEinity capillary electrophoresis for immunoassay. Anal Chem 2001 73 1472-9. 

CDT is also assayed extensively, especially in Europe, for detection of alcohol abuse. Other proteins, such as tti-acid glycoprotein, are carbohydrate deficient in this case as well. The gold standard for assessment is HPLC, although both capillary electrophoresis and immunoassays are more commonly used in clinical settings. Immunoassays in particular are poorly standardized, both qualitatively and quantitatively positive tests should be confirmed by an alternative method." Genetic variants of Tf may also complicate interpretation of results. 

Schmalzing D, Nashabeh W, Yao XW, Mhatre R, Regnier FE, Afeyan NB. Capillary electrophoresis-based immunoassay for cortisol in serum. Anal Chem 1995 67 606-12. 

Chemical analysis systems, such as spectrophotometry, high-performance liquid chromatography, capillary electrophoresis, and immunoassays, always consist of a combination of a reaction or separation and a detection system. In the following section, some generic features for chemical... 

Zhang X, Zhang Z (2012) Capillary electrophoresis-based immunoassay with electrochemical detection as rapid method for determination of saxitoxm and decarbamoylsaxitoxm in shellfish samples. J Food Compos Anal 28 61-69... 

Sulfonylureas are not directly amenable to gas chromatography (GC) because of their extremely low volatility and thermal instability. GC has been used in conjunction with diazomethane derivatization, pentafluorobenzyl bromide derivatization, and hydrolysis followed by analysis of the aryl sulfonamides. These approaches have not become widely accepted, owing to poor performance for the entire family of sulfonylureas. Capillary electrophoresis (CE) has been evaluated for water analysis and soil analysis. The low injection volumes required in CE may not yield the required sensitivity for certain applications. Enzyme immunoassay has been reported for chlorsulfuron and triasulfuron, with a limit of detection (LOD) ranging from 20 to 100 ng kg (ppt) in soil and water. 

Yang WC, Schmerr MJ, Jackma R et al (2005) Capillary electrophoresis-based noncompetitive immunoassay for the prion protein using fluorescein-labeled protein A as a fluorescent probe. Anal Chem 77 4489 1494... 

Also, specific chapters deal with the use of CL reactions as detection mode in FIA (Chapter 12), in separational techniques, such as liquid chromatography (LC) (Chapter 14) or capillary electrophoresis (CE) (Chapter 15), in immunoassay (Chapter 18), and in the development of sensors (Chapter 20). The recent use of this technique for the analysis of DNA (Chapter 19) and a photosensitized CL mode for medical routine and industrial applications (Chapter 17) are also considered in this book. 

Bromberg, A. and R. A. Mathies. Homogeneous immunoassay for detection of TNT and its analogues on a microfabricated capillary electrophoresis chip. Anal. Chem. 75, 1188-1195 (2003). 

JP Ou, QG Wang, TM Cheung, STH Chan, WSB Yeung. Use of capillary electrophoresis-based competitive immunoassay for a large molecule. J Chromatogr B 727 63-71, 1999. 

W Thormann, M Lanz, J Caslavska, P Siegenthaler, R Portmann. Screening for urinary methadone by capillary electrophoretic immunoassays and confirmation by capillary electrophoresis mass spectrometry. Electrophoresis 19 57-65, 1998. 

MJ Schmerr, A Jenny. A diagnostic test for scrapie-infected sheep using capillary electrophoresis immunoassays with fluorescent-labeled peptides. Electrophoresis 19 409-414, 1998. 

L Ye, C Le, JZ Xing, M Ma, R Yatscoff. Competitive immunoassay for cyclosporine using capillary electrophoresis with laser induced fluorescence polarization detection. J Chromatogr B 714 59-67, 1998. 

CAE employing antibodies or antibody-related substances is currently referred to as immunoaf-hnity capillary electrophoresis (lACE), and is emerging as a powerful tool for the identification and characterization of biomolecules found in low abundance in complex matrices that can be used as biomarkers, which are essential for pharmaceutical and clinical research [166]. Besides the heterogeneous mode utilizing immobilized antibodies as described above, lACE can be performed in homogeneous format where both the analyte and the antibody are in a liquid phase. Two different approaches are available competitive and noncompetitive immunoassay. The noncompetitive immunoassay is performed by incubating the sample with a known excess of a labeled antibody prior to the separation by CE. The labeled antibodies that are bound to the analyte (the immuno-complex) are then separated from the nonbound labeled antibody on the basis of their different electrophoretic mobility. The quantification of the analyte is then performed on the basis of the peak area of the nonbonded antibody. 

Figure 19-7 Scatchard plot for binding of antigen (X) to antibody (P). The antibody binds the explosive trinitrotoluene (TNT). The antigen is a fluorescent analog of TNT. From the slope, the binding constant for the reaction P + X PX is K 4.0 > 109M 1. [Derived from Figure 4 of A. Bromberg and R. A. Mathies, "Homogeneous Immunoassay for Defection of TNT on a Capillary Electrophoresis Chip"Anal. Chem. 2003, 75, 1188]...

This chapter presents an approach to perform enzyme linked immunosorbent assays (ELISA) in a microfluidic format with electrochemical detection. This field of analytical chemistry has shown a strong activity in recent years, and many reports have presented the use of capillary-sized reactors for running immunoassays either in homogeneous format (where the antigen-antibody complex and the labelled revelation reagents are separated prior to detection, as for instance by capillary electrophoresis [1-3]) or in heterogeneous format (where the antibody is immobilised on the inner surface of the microsensor device [4] or on microbeads [5,6]). 

Schmalzing D, Koutny LB, Taylor TA, Nashabeh W, Fuchs M. Immunoassay for thyroxine (T4) in serum using capillary electrophoresis and micromachined devices. J Chromatogr, B Biomed Sci Appl 1997 697 175-180. 

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