A quartz crystal microbalance displacement assay for Listeria monocytogenes

A novel, piezoelectric, quartz crystal microbalance (QCM) biosensor has been developed for the detection of Listeria monocytogenes. The Listeria was immobilized on the gold surface of the crystals using different immobilization approaches, Using a liquid flow cell, it was possible to directly monitor the antigen (Ag)-antibody (Ab) binding without the use of a label, i.e. enzymes, radioactive compounds, etc. The calibration curve was prepared using a displacement assay with a response range from 2.5 x 10(5) to 2.5 x 10(7) cells/crystal. The assay was also performed in milk which was injected with the non-specific antigen Serratia or Listeria. The method is as sensitive as ELISA and results can be obtained in less than 15 min.