Flow-through immunofiltration assay system for rapid detection of E-coli O157 : H7

A flow-through amperometric immunofiltration assay system based on disposab le porous filter-membranes for rapid detection of Escherichia coli O157:H7 has been developed. The analytical system utilizes flow-through, immunofilt ration and enzyme immunoassay techniques in conjunction with an amperometri c sensor. The parameters affecting the immunoassay such as selection of app ropriate filter membranes, membrane pore size, antibody binding capacity an d the concentrations of immunoreagents were investigated and optimized. Non -specific adsorption of the enzyme conjugate was investigated and minimized . A sandwich scheme of immunoassay was employed and the immunofiltration sy stem allows to specifically and directly detect E. coli cells with a lower detection limit of 100 cells/ml. The working range is from 100 to 600 cells /ml with an overall analysis time of 30 min. No pre-enrichment was needed. This immunosensor can be easily adapted for assay of other microorganisms a nd may be a basis for a new class of highly sensitive bioanalytical devices for rapid quantitative detection of bacteria. (C) 1999 Elsevier Science S. A. All rights reserved.