A graphene electrode functionalized with aminoterephthalic acid for impedimetric immunosensing of Escherichia coli.

A screen-printed electrode prepared from graphene oxide (GO) has been functionalized with 2-aminoterephthalic acid, followed by the exploitation of this functional material in an electrochemical immunoassay for Escherichia coli (E. coli) by immobilizing the antibody on its surface. The functionalization steps followed a straightforward approach and were proven by various instrumental techniques. The detection of E. coli with antibody immobilized electrodes was performed using electrochemical impedance spectroscopy. The analyses were carried out using the hexacyanoferrate redox couple as the electrochemical probe. The present method has a wide analytical range (from 2.2 × 102 to 2.2 × 108 cfu.mL-1), a low limit of detection (2 cfu.mL-1), fast response (4 min), and good stability (up to 2 months). The analytical performance of the biosensor was comparable to the previously reported electrochemical biosensors for E. coli. As such, the approach of functionalization of graphene with 2-aminoterephthalic acid should be useful to allow the development of other similar sensing systems for other environmentally and clinically important analytes. Graphical abstractSchematic representation of the preparation and the function of an amino-functionalized graphene oxide (NH2-GO) based impedimetric biosensor for the electrochemical detection of E. coli.