Flow injection immunoassays

Figure 18 Flow chart of the automated on-line flow injection immunoassay (FllA). Six steps are involved in each cycle (1) addition of antibody and incubation (2) addition of analyte (or standard) and incubation (3) addition of enzyme-tracer and incubation (4) addition of substrate and incubation (5) downstream measurement of fluorescence (6) regeneration of affinity column...

J. Gascon, A. Oubina, B. Ballesteros, D. Barcelo, F. Camps, M.P. Marco, M.A. Gonz lez-Martmez, S. Morais, R. Puchades, and A. Maquieira, Development of a highly sensitive enzyme-linked immunosorbent assay for atrazine. Performance evaluation by flow injection immunoassay. Anal Chim. Acta 347, 149-162 (1997). 

M. Franek, A. Deng, and V. Kolar, Performance characteristics for flow injection immunoassay using monoclonal antibodies against s-triazine and 2,4-D herbicides. Anal. Chim. Acta 412,19-27 (2000). 

BMP-IA bacterial magnetic particle-based immunoassay FIIA flow-injection immunoassay PFIA polarization fluoroimmunoassay. b BDD12AC benzyldimethyldodecylammonium chloride DDAC didecyldimethylammonium chloride. 

L. Locascio-Brown, A. L. Plant, V. Horvath, and R. A. Durst, Liposome flow injection immunoassay Implications for sensitivity, dynamic range, and antibody regeneration. Anal. Chem. 62, 2587-2593... 

Figure 3.29 — (A) Immunosensor scheme A Cell inlet tubing B transparent PTFE tube (1.6-mm ID x 3-mm OD C immunosorbent D frit. (B) Outline of flow-injection immunoassay procedure. The assay buffer is posphate buffered saline (PBS) at pH 7, and flow-rates and times (min) are given in the figure. Immobilized anti-mouse IgG modified sample (mouse IgG) injected at T = 0 change of the flow-rate and buffer at T = 4 injection of hydrogen peroxide in a basic medium at T = 5 then, emission monitoring and regeneration step acridinium ester-labelled antibody (emitter = N-methylacridine). (Reproduced from [218] with permission of Elsevier Science Publishers).

The utilization of lAC in analytical methods has received increasing retention in recent years [23,24], Of particular interest is the use of immobilized antibody columns in performing immunoassays, a technique known as a chromatographic immunoassay or flow-injection immunoassay. This approach has already been reported in a number of formats such as those involving simple analyte adsorption/desorption, sandwich immunoassays, competitive binding immunoassays, and multianalyte methods (see Figure 13,9) [23,24,73,74], Typical advantages of these methods include decreased analysis times and improved precision versus manual immunoassays. 

Locascio-Brown, L., Plant, A. L., Chesler, R., Kroll, M., Ruddel, M., and Durst, R. A. (1993). Liposome-Based Flow-Injection Immunoassay for Determining Theophylline in Serum. Clin. Chem. 39 386-391. 

Another important technique in lAC is the use of immobilized antibody columns to perform chromatographic (or flow-injection) immunoassays. One way this can be done is in a competitive binding format. The simplest approach to a competitive binding scheme is to mix the sample and a labeled analyte analog (the label) and apply these simultaneously to the lAC column this is a method known as a simultaneous injection competitive binding immunoassay. If the sample is applied to the lAC column and followed later by a separate injection of the label, then the technique is called a sequential injection competitive binding immunoassay. In both formats, an indirect measure of the sample analyte is obtained by examining the amount of label that elutes in either the nonretained or retained lAC fractions. 

Wu J, Tang J, Dai Z et al (2006) A disposable electrochemical immunosensor for flow injection immunoassay of carcinoembryonic antigen. Biosens Bioelectron 22 102-108... 

Shellum C and Gubitz G 1989 Flow injection immunoassays with acridinium... 

The Automation of Two Flow-Injection Immunoassays Using a Flexible Software... 

In this study two different flow-injection immunoassays are presented as well as the flexible automation system CAFCA (Computer Assisted Flow Control Analysis), which has been used for their control, uptake measurement, evaluation and visualization. Both immunoassays (a heterogeneous and a homogeneous assay) are based on the principles of flow-injection analysis and were developed for reliable, fast monitoring of relevant proteins in animal cell cultivation processes. Off-line applications of measurements of medium samples as well as online application during a mammalian cell cultivation are presented. All results are compared to results obtained with ELISA (Enzyme Linked Immunosorbend Assay). The requirements of the automation of flow-injection immunoassays with respect to their flexible control are discussed. 

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