Listeria monocytogenes detection with surface plasmon resonance and protein arrays

In this study label-free a SPR immunosensor and a protein array based methods were used for their application in bacterial detection. L. monocytogenes, one of the most difficult to treat bacteria, was used as model pathogen. While the use of DNA arrays for bacteria detection and identification is largely documented, no studies are available on protein array (PA) based bacteria detection. In protein array approach an affinity-purified monoclonal antibody was used as capture antibody. Protein array detection limit was of 10²-10³CFU/mL. SPR immunoassays were prepared by chemically binding L. monocytogenes cells on a proper gold substrate. After immobilization of antigen on gold substrate, a further incubation with anti-L. monocytogenes antibodies was performed. The technique was revealed as powerful and fast method for the monitoring of binding between the investigated antigen and antibodies. On the other side, array based methods, although more expensive due to the labelling step, can be used with a set of species-specific antibodies allowing for simultaneous detection of multiple pathogens in a single hybridization step in no more then 2.5 h.