Rapid Detection of Microorganisms in Milk Using an In-situ Prepared Nano-functionalized Gold Electrode

An in-situ, facile and rapid method is developed to prepare a nano-functionalized gold electrode. After electrolysis at constant potential of +2 V in PBS (pH 7.0) for 10 min, a rough, nano-porous film formed on the surface of a polished gold plate electrode. This new nano-functionalized gold electrode could be applied for the rapid quantification of bacteria in milk. The detection was based on the catalysis of lipid peroxidation on cell membrane of bacteria by nano-porous Au film. The response of the current in chronoamperometry linearly responded to the bacterial content in milk, which was calibrated by the national standard method (Standard plate count method). Therefore the accurate quantity of bacteria was obtained from the current response on prepared electrode. The results showed that the bacteria could be detected in the range of 1.1 × 103−2.5 × 107 cfu mL−1 within 1 h.