A multicolorimetric assay for rapid detection of Listeria monocytogenes based on the etching of gold nanorods.

Listeria monocytogenes (L. monocytogenes) is one of the most common food-borne pathogens. The authors describe a sensitive and reliable multicolorimetric assay for L. monocytogenes using a sensing system based on TMB2+ etching of gold nanorods. Apt-MNP was used as the capture probe, and IgY-BSA-MnO2 NPs was chosen as an oxidase-like nano-artificial enzyme to oxidize TMB to generate TMB2+. Under the optimized conditions, the longitudinal shift of localized surface plasmon resonances had a linear correlation with the L. monocytogenes concentration in the range between 10 to 106 cfu mL-1. Meanwhile, the sensing system can generate vivid color responses as colorful as a rainbow, and the limit of detection is as low as 10 cfu mL-1 at a glance. Recoveries ranging from 97.4 to 101.3% are found when analyzing spiked food samples without pre-enrichment. In our perception, it shows promise in rapid instrumental and on-site visual detection of L. monocytogenes.