Organic
metallic nanohybrids (NHs), in which many small metal nanoparticles
are encapsulated within a conductive polymer matrix, are useful as
sensitive electrochemical labels because the constituents produce
characteristic oxidation current responses. Gold NHs, consisting of
gold nanoparticles and poly(m-toluidine), and copper
NHs, consisting of copper nanoparticles and polyaniline, did not interfere
with each other in terms of the electrochemical signals obtained on
the same electrode. Antibodies were introduced into these NHs to function
as electrochemical labels for targeting specific bacteria. Electrochemical
measurements using screen-printed electrodes dry-fixed with NH-labeled
bacterial cells enabled the estimation of bacterial species and number
within minutes, based on the distinct current response of the labels.
Our proposed method achieved simultaneous detection of enterohemorrhagic Escherichia coli and Staphylococcus
aureus in a real sample. These NHs will be powerful
tools as electrochemical labels and are expected to be useful for
rapid testing in food and drug-related manufacturing sites.