A remarkable sensitivity enhancement in a gold nanoparticle-based lateral flow immunoassay for the detection of Escherichia coli O157:H7

Because of the distinctive features of ease-of-use, low cost and portable detection, a gold nanoparticle (AuNP) based lateral flow immunoassay (LFA) is an effective and currently used method for the detection of Escherichia coli O157:H7; however, its low sensitivity limits its practical use. In the present study, the size and uniformity of AuNPs have been systematically optimized to maximally amplify both the visual inspection signals (the color of test line) and the quantitative data (light intensity) recorded using a bioassay reader. The remarkable enhancement of detection sensitivity can be increased to 10(2) colony forming units per mL by taking advantage of the optimized AuNPs and the separated incubation of the AuNPs/antibody/E. coli O157: H7 complex. Quantitative detection of E. coli O157: H7 was partially obtained in a wide concentration range with good repeatability. The new, optimized AuNPs-based LFA is well suited to fast quantitative and qualitative food analysis.