A Nafion/AChE-cSWCNT/MWCNT/Au-based amperometric biosensor for the determination of organophosphorous compounds.

In the present study, a biosensor was developed for the detection of organophosphorous compounds. Core electrode of a working electrode was obtained by depositing the paste of Gold nanoparticles and Multi-walled Carbon Nanotubes on a gold wire. The acetylcholinesterase enzyme was immobilized on carboxylated Single-walled Carbon Nanotubes and pasted onto a core of electrode followed by coating with a nafion layer to prevent enzyme leaching from the electrode. This electrode was further used as a working electrode in the sensor. This sensor worked on the AChE inhibition mechanism where the signal is inversely proportional to the amount of organophosphorous compounds. The electrocatalytic activity of this sensor was observed at a potential of +0.360 mV. The standardized conditions for this sensor were pH at 7.0, temperature at 30°C and response time at less than 10s. The linear working range of this biosensor was 0.1-130 µM with the lowest detection limit (LOD) of 1.9, 2.3, 2.2 and 2.5 nM for Methyl Parathion, Monocrotophos, Chlorpyrifos and Endosulfan, respectively. The biosensor showed excellent reusability (upto 55 times) and can be stored stably for 2 months.