Detection of Listeria monocytogenes Using Luminol-Functionalized AuNF-Labeled Aptamer Recognition and Magnetic Separation

A capture probe was constructed using a combination of magnetic Fe3O4 nanoparticles and an aptamer directed toward Listeria monocytogenes. A signal probe was prepared by combining luminol-functionalized flowerlike gold nanoparticles, obtained by combining luminol with chitosan bearing a complementary sequence of the aptamer. The complex consisting of the capture probe and signal probe could be removed through magnetic separation. Where the target was present within a sample, it competed with the complementary sequence for binding to the aptamer, causing a change of the chemiluminescent signal. The results indicated that a good linear relationship existed over the concentration range 1.0 x 10(1)-1.0 x 10(5) CFU.mL(-1). It was established that it was feasible to use this approach to detect L. monocytogenes at levels as low as 6 CFU.mL(-1) in milk samples.