Microfluidic impedimetric sensor for soil nitrate detection using graphene oxide and conductive nanofibers enabled sensing interface

This paper reports on a microfluidic impedimetric nitrate sensor using a graphene oxide (GO) nanosheets and poly(3,4-ethylenedioxythiophene) nanofibers (PEDOT-NFs) enabled electrochemical sensing interface. The sensor has demonstrated the ability to accurately detect and quantify nitrate ions in real samples extracted from soil. The PEDOT NFs-GO composite serves as an effective matrix for immobilization of nitrate reductase enzyme molecules. The oxygenated functional groups available at GO allows an increased charge transfer resistance of the electrochemical electrode. Microscopic, spectroscopic, and electrochemical studies were systematically conducted to illustrate synergic interactions between the GO and PEDOT NFs. The sensor provides a sensitivity of 61.15 Omega/(mg/L)/cm(2) within a wide concentration range of 0.44-442 mg/L for nitrate ions in agricultural soils. The detection limit of the sensor is 0.135 mg/L with good specificity, reliability, and reproducibility. (C) 2016 Elsevier B.V. All rights reserved.