Ag. Gehring et al., ENZYME-LINKED IMMUNOMAGNETIC ELECTROCHEMICAL DETECTION OF SALMONELLA-TYPHIMURIUM, Journal of immunological methods, 195(1-2), 1996, pp. 15-25
There is a need for rapid methods to detect pathogenic bacteria in foo
d products as alternatives to the current laborious and time-consuming
culture procedures. We report a microbial detection technique that co
mbines the selectivity of antibody-coated superparamagnetic beads with
the rapidity and sensitivity of electrochemical detection in a format
termed enzyme-linked immunomagnetic electrochemistry. In it, Salmonel
la typhimurium were sandwiched between antibody-coated magnetic beads
and an enzyme-conjugated antibody. With the aid of a magnet, the beads
(with or without bound bacteria) were localized onto the surface of d
isposable graphite ink electrodes in a multi-well plate format. Enzyme
substrate was added and conversion of substrate to an electroactive p
roduct was measured using electrochemical detection. The electrochemic
al response was directly proportional to the number of captured bacter
ia. Using this technique, a minimum detectable level of 8 x 10(3) cell
s/ml of Salmonella typhimurium in buffer was achieved in ca. 80 min.