Immunoassay automation

Chan DW. Immunoassay automation. From concept to system performance. In Kost GJ, ed. Handbook of clinical automation, robotics, and optimization. New York, John Wiley Sons, 1996 419-41. 

Chan, DW. Immunoassay automation An updated guide to systems. San Diego, CA Academic Press, 1995. 

EiaFoss E. coli 0157 (Foss Electric A/S) 0157 Fluorescent Immunoassay Automated ... 

D. W. Chan (ed.), Immunoassay Automation A Practical Guide, Academic Press, New York, 1992. 

EIAs can be used per se or with a spectrophotometer. Traditionally, EIAs have been developed in 96-weU microtiter plates which provide the immobilization support for the assay, the reaction vessel, and, when linked to a spectrophotometer-based reader, a rapid means to detect and quantify the color resulting from interaction of a substrate with the antibody—antigen—enzyme complex. Automated immunoassay analyzers targeted primarily for use in the clinical laboratory have taken automation one step further, utilizing robotics to carry out all reagent additions, washings, and final quantification including report preparation. 

Immunosensors promise to become principal players ia chemical, diagnostic, and environmental analyses by the latter 1990s. Given the practical limits of immunosensors (low ppb or ng/mL to mid-pptr or pg/mL) and their portabiUty, the primary appHcation is expected to be as rapid screening devices ia noncentralized clinical laboratories, ia iatensive care faciUties, and as bedside monitors, ia physicians offices, and ia environmental and iadustrial settings (49—52). Industrial appHcations for immunosensors will also include use as the basis for automated on-line or flow-injection analysis systems to analyze and control pharmaceutical, food, and chemical processing lines (53). Immunosensors are not expected to replace laboratory-based immunoassays, but to open up new appHcations for immunoassay-based technology. 

A number of soHd-phase automated immunoassay analyzers have been used for performing immunoassays. Table 5 (96) provides usefiil information on maximum tests that can be mn per hour, as well as the maximum number of analytes per sample. A number of immunoassay methods have been found usefiil for environmental analysis (see AUTOMATED INSTRUMENTATION). 

Table 5. Solid-Phase Automated Immunoassay Analyzers ...

See Automated INSTRUMENTATION Immunoassay Medicad diagnostic reagents. 

Enzyme immunosensors are used in flow injection systems and Hquid chromatography to provide automated on-line analyses (71—73). These systems are capable of continuously executing the steps involved in the immunoassays, including the binding reactions, washing, and the enzyme reaction, in about 10 minutes. 

The main advantage of a homogeneous immunoassay, compared to a heterogeneous immunoassay, is the absence of a separation step. This translates into a simpler procedure and easier automation. However, homogeneous assays are typically less sensitive and more susceptible to sample interferences which are removed in a separation step. 

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...

King K.D., Vanniere J.M., LeBlanc J.L., Bullock K.E., Anderson G.P., Automated fiber optic biosensor for multiplexed immunoassays, Environ. Sci. Technol. 2000 34 2845-2850. 

J. Tschmelak, G. Proll, and G. Gauglitz, Ultra-sensitive fully automated immunoassay for detection of propanil in aqueous samples steps of progress toward sub-nanogram per liter detection. Anal. Bioanal. Chem. 379, 1004-1012 (2004). 

B.L. Haller, K.A. Fuller, W.S. Brown, J.W. Koenig, B J. Eveland, and M.G. Scott, Two automated prolactin immunoassays evaluated with demonstration of a high-dose hook effect in one. Clin. Chem. 38,... 

---