Researchers have designed a novel biosensor capable of detecting trace amounts of organophosphorous pesticides in food and environmental samples1. The researchers produced their device by modifying a gold electrode with a nanocomposite coated with adult rat brain protein.
Organophosphorous pesticides can inhibit the activity of an important enzyme acetylcholinestarase (AChE) in the brain and shoot up the neurotransmitter acetylcholine leading to exhaustion and paralysis of brain cells. It is therefore important to monitor levels of organophosphorous pesticides in food and environmental samples.
Existing sensors have several drawbacks, including low sensitivity, low storage stability and lack of reusability. The researchers tried to overcome these by producing a nanocomposite from zinc sulphide nanoparticles and polyindole. They coated the nanocomposite with AChE isolated from adult rat brain. They modified gold wire with the resulting AChE-coated nanocomposite to yield the biosensor and compared its efficacy with standard wire electrodes made from silver and platinum.
Through electrochemical studies on two organophosphorous pesticides, they found that although the biosensor effectively detected both pesticides, it was particularly sensitive to malathion.
The biosensor was capable of detecting the pesticides even in the presence of interfering heavy metals such as zinc, copper, cadmium, nickel, iron and lead. The biosensor lost 50% of its initial current response when stored at 40 °C for 60 days, which is an improvement over earlier devices.
"This biosensor could be used for the direct detection of pesticides in samples such as soil, vegetables, milk and water," says lead researcher C. S. Pundir.
