On-spot biosensing device for organophosphate pesticide residue detection in fruits and vegetables

[Display omitted] •We report the portable device development using organophosphate hydrolase (OPH).•OPH, being superior over AChE, is expressed from the ‘opd’ gene.•Residual pesticides in fruits and vegetables are detected using mentioned device.•Such OPH based on-spot biosensing device is first-ever reported in this work. Acetylcholinesterase (AChE), a widely used enzyme for inhibition-based biosensors in pesticide residues detection, lags due to multiple-step operation, time-consuming incubation and reactivation/regeneration steps. Herein, this endeavour reports the development of Organophosphate Hydrolase (OPH), which has functional superiority over the AChE and explored in on-spot biosensing device for organophosphate pesticide residue detection in fruits and vegetables. The organophosphate degrading enzyme OPH is expressed from the ‘opd’ gene through biotechnological tools. The OPH exhibited its best activity at pH 8.0 and subsequently thermal inactivation over 37 °C. The activity of the purified OPH enzyme was found 2.75 U mL−1 at λmax 410 nm. Furthermore, the developed OPH is integrated into 96 well plate format with our previously reported UIISScan 1.1, an advanced imaging array technology based field-portable high-throughput sensory system. The developed biosensor revealed a linear range from 100 ng mL−1 to 0.1 ng mL−1 for detection of organophosphate pesticide residues with a negative slope i.e. y = 235.678x (ng mL−1) – 62.8725 with R2 = 0.99991 and n = 23. Moreover, the applicability of the developed biosensor was tested for market available fruits and vegetables. This is the first-ever reported OPH mediated on-spot biosensing device for pesticide residue detection in fruits and vegetables to the best of our knowledge.