Dual colorimetric/electrochemical sensor of carbaryl in fruits on microfluidic paper-based analytical device connected with smartphone readout

A dual colorimetric/electrochemical sensor integrated with a microfluidic paper-based analytical device (mu PAD) is created for rapid and sensitive detection of cabaryl in fruit. For colorimetric sensor, quercetin modified silver nanoparticle (QCT-AgNPs) is synthesized via self-reduction, resulting in the color change from green to dark green in the presence of cabaryl, which can be readily observed via naked eyes. This colorimetric sensor provides a linear response of 5 - 50 mu M quantified by Image J software. For electrochemistry, AgNPs/MXene nanocomposite electrode offers high electrocatalytic activity towards the detection of carbarly with a linear range of 0 - 60 mu M and a detection limit of 0.01 mu M. The limit of detection values obtained from this dual sensor are lower than a cut-off of carbaryl residue in food, which is 7 mg.kg- 1 (35 mu M) verifying the desired sensitivity of this platform. Ultimately, this dual sensor is successfully applied for on-site detection of carbaryl in the orange samples read out on the smartphone with satisfactory results.