Amperometric acetylcholinesterase biosensor for pesticides monitoring utilising iron oxide nanoparticles and poly(indole-5-carboxylic acid)

A new electrochemical sensing device was constructed for determination of pesticides. In this report, acetylcholinesterase was bioconjugated onto hybrid nanocomposite, i.e. iron oxide nanoparticles and poly(indole-5-carboxylic acid) (Fe3O4NPs/Pin5COOH) was deposited electrochemically on glassy carbon electrode. Fe3O4NPs was showed as an amplified sensing interface at lower voltage which makes the sensor more sensitive and specific. The enzyme inhibition by pesticides was detected within concentrations ranges between 0.1–60 and 1.5–70 nM for malathion and chlorpyrifos, respectively, under optimal experimental conditions (sodium phosphate buffer, pH 7.0 and 25 °C). Biosensor determined the pesticides level in water samples (spiked) with satisfactory accuracy (96%–100%). Sensor showed good storage stability and retained 50% of its initial activity within 70 days at 4 °C.