Direct Detection System for <i>Escherichia coli</i> Using Au&#x2013;Ag Alloy Microchips

다국어 초록 (Multilingual Abstract)

<P>Au–Ag alloy nanoparticles (NPs) were prepared by the reduction of metal ion mixtures in aqueous sodium citrate solution using sodium borohydride (NaBH<SUB>4</SUB>). The resulting Au–Ag alloy NPs were analyzed by various techniques. Alloy-attached chips for the detection of microorganisms were fabricated simply by the attachment of Au–Ag alloy nanoparticles onto glass slides after silanization through self-assembled monolayers (SAMs) for the formation of activated amine (−NH<SUB>2</SUB>) as a terminal function group. The alloy-attached chips were investigated for their ability to bind the target <I>Escherichia coli</I> (<I>E. coli</I>) in water. <I>E. coli</I> was detected in water as a function of time and concentration by UV–vis spectroscopic measurements based on the interaction between the alloy-attached chip and <I>E. coli</I>. Field-emission scanning electron microscopy (FE-SEM) was used to directly observe the <I>E. coli</I> captured on the alloy chips. These studies demonstrated that <I>E. coli</I> in drinking water can be directly detected with Au–Ag alloy microchips without requiring any interaction between an antibody and an antigen.</P><P><B>Graphic Abstract</B>
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