the most commonly used toxic substance in pesticides, can lead to
cholinergic dysfunction, which affects the health of both humans
and animals. Rapid, sensitive and cost-effective detection of OP
neurotoxins is important for protecting water resources and food
supplies, in the defense against terrorist activity, and for monitoring
detoxification processes. Traditional laboratory-based analytical
techniques for detecting OPs include chromatography and
mass spectrometry which are rather time-consuming and expensive
(Sherma, 1993). Enzyme-based biosensors using carbon nanotubes
as the transducer have been used for highly selective and
rapid detection of pesticides. These enzymatic biosensors can
either be used for direct detection based on the catalytic activity
of organophosphorus hydrolase (OPH) (Mulchandani et al., 2001)
or based on the inhibition of activity of several enzymes present
in pesticides like acetylcholinesterase (AChE), butyrylcholinesterase
(BChE) and tyrosinase (Tyr) (Andreescu and Marty,
2006 and Tanimoto de Albuquerque and Ferreira, 2007).