Ultrasensitive detection of organophosphate insecticides by carbon nanotube field-effect transistor

Cobalt ferrite/semiconducting single-walled carbon nanotubes based field-effect transistor for determination of carbamate pesticides

Carbaryl and carbofuran are the carbamate pesticides which have been widely used worldwide to control insects in crops and house. If the pesticides entered in to the food products and drinking water, they could cause serious health effects in humans. Therefore, the development of a rapid, simple, sensitive and selective analytical device for on-site detection of carbamates is crucial to evaluate food and environmental samples. Recently, semiconducting single-walled carbon nanotube-based field effect transistors (s-SWCNT/FETs) have shown several advantages such as high carrier mobility, good on/off ratio, quasi ballistic electron transport, label-free detection and real-time response. Herein, cobalt ferrite (CFO) nanoparticles decorated s-SWCNTs have been prepared and used to bridge the source and drain electrodes. As-prepared CFO/s-SWCNT/FET had been used for the non-enzymatic detection of carbaryl and carbofuran. When used as a sensing platform, the CFO/s-SWCNT hybrid film exhibited high sensitivity, and selectivity with a wide linear range of detection from 10 to 100 fMand the lowest limit of detections for carbaryl (0.11 fM) and carbofuran (0.07 fM) were estimated. This sensor was also used to detect carbaryl in tomato and cabbage samples, which confirmed its practical acceptance. Such performance may be attributed to the oxidation of carbamates by potent catalytic activity of CFO, which led to the changes in the charge transfer reaction on the s-SWCNTs/FET conduction channel. This work presents a novel CFO/s-SWCNT based sensing system which could be used to quantify pesticide residues in food samples.