Detection of the shrimp pathogenic bacteria, Vibrio harveyi, by a quartz crystal microbalance-specific antibody based sensor

An immunosensor based on a quartz crystal microbalance (QCM) was developed for detection of Vibrio harveyi (V. harveyi), a pathogenic bacteria causing morbidity and even a high level of fatality in commercial shrimp cultures, including Penaeus monodon. Immobilization of a monoclonal antibody (MAb) against V. harveyi onto the gold electrode of a QCM plate involved a three-step procedure: (1) the formation of a self-assembled monolayer (SAM) of a carboxyl-terminated alkanethiol, (2) activation of the carboxyl groups by N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), and (3) attachment of the MAb to the activated carboxyl groups. The developed QCM-based immunosensor could be used for the detection of V. harveyi in a working range of 103–107 CFU/mL, with no detectable cross-reactivity to Vibrio vulnificus and Vibrio parahaemolyticus. Controlling the density of surface-immobilized MAb, by the formation of mixed SAMs containing hydroxyl-terminated alkanethiol in combination with the treatment of 1% (w/v) bovine serum albumin (BSA) as a blocking reagent, can significantly improve the binding efficiency of the targeted bacteria.