Enzyme-based biosensors pesticide measuring principles

OPH-based biosensors have been fully discussed in previous reviews [2,165]. AChE-based biosensors are based on the principle that OP pesticides have an inhibitory effect on the activity of AChE that may be permanent or partially reversible. The extent of the inhibition is directly related to the concentration of the pesticide and therefore enzyme activity may be used as a measure of the inhibition [166]. The amperometric measurement of AChE activity can be based on the measurement of any of the following three mechanisms [167] (1) production of hydrogen peroxide from choline, (2) oxygen consumption during the enzyme reaction or (3) production of electroactive compounds directly from the oxidation of acetylthiocholine chloride such as thiocholine. The measurement of hydrogen peroxide and oxygen consumption has been described in more details in other reviews [167]. 

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