Enzyme-linked immuno-strip biosensor to detect Escherichia coli O157:H7

A strip-based biosensor using the enzyme-linked immunosorbent assay technique was fabricated to detect Escherichia coli O157:H7. Two types of antibody specified to E. coli O157:H7 were used to form sandwich-binding complexes. To fabricate an immuno-strip, capture antibody (monoclonal antibody) was immobilized onto signal generation pad and polyclonal antibody conjugated with horseradish peroxidase (HRP) was utilized as detection antibody. Four different functional membranes have been used to fabricate immuno-chromatographic assay strip. A sample application pad was a glass fiber membrane pre-treated with polyvinyl alcohol. A conjugate release pad was fabricated using a glass membrane. A signal generation pad was made on nitrocellulose membrane. Finally, a cellulose membrane was used as an absorption pad. Under optimal conditions of analysis, a color signal in proportion to the E. coli O157:H7 concentration was measured using a detector. The measurement range was 1.8×103–1.8×108 CFU/mL.