Chemically Modified Electrode for Liposome-Mediated Homogeneous Immunoassay

Durst, Richard A.; Kannuck, Rosanne M.

doi:10.1016/b978-0-08-037933-3.50009-0

Cited by 3 publications

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Flow‐injection liposome immunoanalysis (FILIA) with electrochemical detection

Edwards

Durst

1995

Electroanalysis

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An automated flow-injection liposome immunoanalysis (FILIA) system with electrochemical detection has been developed to measure the herbicide alachlor. The computer-controlled system is composed of commercially available components, with the exception of the reusable immunoreactor column packing material (glass beads) which is covalently coated with antibody specific for the analyte of interest. Use of such components affords full automation while simplifying the construction of, and modifications to, the system. The assay is based on competition in the immunoreactor column between alachlor-tagged liposomes containing an electroactive marker, ferrocyanide, and free abdchlor, with quantitative signal amplification provided by lysis of bound liposomes with surfactant to release the marker. An optimized assay pennits the detection of 0.5 ng alachlor in a spiked water sample. The electrochemical detector is operated in the controlled-potential, amperometric mode in which ferrocyanide is oxidized at low potential ( + 0.330 V vs. Ag/AgCl), thus minimizing electroactive interferences.The relationships among the various operational parameters (e.g., potential, flow rate, assay time, composition of solutions) are discussed, and the optimization of these parameters is presented.

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