Development of Organic-Inorganic Nanostructure Labels for Food-poisoning Bacteria

In this paper, we describe a simple strategy to detect food-poisoning bacteria using the spectroscopic and electrochemical properties of organic-inorganic nanostructures composed of electrically conductive polyaniline-coated copper nanoparticles. Antibody-introduced nanostructures specifically bind to cells via antigens and function as nanometer-sized labels. Attempting the quantification of Staphylococcus aureus using nanostructure labels, we found that the absorbance of the free label in the supernatant decreased as the number of bacterial cells increased, indicating that the labeled cells were obtained as precipitates. Furthermore, the peak current (Ip) based on the number of labels bound to cells on the electrode increased with the number of bacterial cells. Thus, the introduction of antibodies into nanostructures has made it possible to electrochemically and spectroscopically quantify the causative bacteria of food poisoning.