Rapid and sensitive immunodetection of Listeria monocytogenes in milk using a novel piezoelectric cantilever sensor

Listeria monocytogenes (LM), an important food-borne pathogen that has a high mortality rate (∼30%), was successfully detected within an hour at the infection dose limit of 103/mL, both in buffer and milk. LM detection was demonstrated using a novel asymmetrically anchored cantilever sensor and a commercially available antibody. Sensor responses were confirmed using a secondary antibody binding step, similar to the sandwich ELISA assays, as a means of signal amplification that also reduced the occurrence of false negatives. Detection of LM at a concentrations of 102/mL was achieved, by incorporating a third antibody binding step, which is an order of magnitude smaller than the infection dose (<1000 cells) for LM. The commercially available antibody for LM used in this work is shown to have low avidity which partially explains the relatively low sensitivity reported for LM as compared to other pathogens.

► Detection sensitivity of the pathogen is demonstrated at infectious dosage level.
► The cantilever sensor showed sensitivity of 30.4 Hz/103 LM cells/mL, and in milk it decreased to 18.2 Hz/103 LM cells/mL.
► Novel triple antibody binding assays on cantilever sensor eliminate false negatives, and enhance measurement sensitivity.
► Tests in milk show that loss of sensor sensitivity is low, and thus can be used in practical food derived liquid samples.