Detection of biological threat agents by immunomagnetic microsphere-based solid phase fluorogenic- and electro-chemiluminescence

This article reviews the recent development of two solid-phase chemilumines cence-based techniques, fluorogenic-chemiluminescence (FCL) and electro-che miluminescence (ECL) for detection of biological threat agents. Both techni ques entail a labeled sandwich immunoassay. The objectives of this work are to develop advanced techniques for sensitive and effective detection of a target analyte, particularly in cases where the analysis includes complex s amples containing multiple contaminating factors. Other important considera tions in developing such detection techniques include the ease of use, the rapid determination of the results, and system automation for field applica tions. In FCL, alkaline phosphatase is used as a label and this technique u tilizes the dual features of fluorescence and visual color generated upon t he presence of the fluorogenic compound, AttoPhos(TM). The assay reaction i s determined by measuring the fluorescence. In ECL, the label is a rutheniu m-trisbipyridal, which is excited to a higher energy state by an electric c urrent-driven redox reaction, and the extent of the reaction is assessed vi a photon emission. Both techniques depend upon the magnetic separation tech nique as a means to isolate the target immunological agents from the sample for analysis. This magnetic capture system allows for a reaction to occur on the electron effective-transfer zone in the ECL and also provides the re action site for the labeled sandwich in the FCL. Comparative studies of the se two techniques for detection of biological threat agents have been perfo rmed and the advantages of using magnetic microspheres versus conventional solid-phase matrices are discussed. (C) 2000 Elsevier Science S.A. All righ ts reserved.