Cholinesterase piezoelectric sensor

Piezoelectric sensors have become a versatile tool in biosensorics to study protein-protein and protein-small molecule interactions. Here we present theoretical background on piezoelectric sensors and instructions, how to modify their surface with various recognition elements for cholinesterases. These recognition elements comprise an organophosphate (paraoxon), a cocaine derivative (BZE-DADOO), and a tricyclic, aromatic compound (propidium). Additionally, a guide to the kinetic evaluation of the obtained binding curves is given in this chapter. 

Teller, C., Halamek, J., Makower,A., Fournier, D., Schulze, H., and Scheller, F. W. (2006) A piezoelectric sensor with propidium as a recognition element for cholinesterases. Sensors and. Actuators B-Chemical 113, 214—221... 

J. Halamek, A. Makower, K. Knosche, P. Skladal and F.W. Scheller, Piezoelectric affinity sensors for cocaine and cholinesterase inhibitors, Talanta, 65 (2005) 337-342. 

Here we show how to modify the piezoelectric surface to develop affinity sensors for detection of small molecular compounds using antibodies and (acetyl)cholinesterases (AChE), respectively. The chemical structures of the described surface modifications are shown in Fig. 

A piezoelectric biosensor, for the detection of several organophosphorus pesticides was developed (Halamek et al., 2005). The sensor was based on the immobilization of a reversible inhibitor of cholinesterase on the surface of the sensor. The binding of AChE to this inhibitor was monitored with a mass-sensitive piezoelectric quartz crystal. In the presence of an inhibiting substance in the sample, the binding of the enzyme to the immobilized compound was reduced, and the decrease of mass change was proportional to the concentration of the analyte in the sample. This sensor was applied to the determination of pesticides in river water samples. 

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