Electrochemical aptasensor for Salmonella detection using Nafion-doped reduced graphene oxide

Abstract

A highly conductive nanocomposite composed of reduced graphene oxide (rGO)–Nafion (Nf) was successfully prepared via a chemical reduction method in this study. The nanocomposite was used to develop an electrochemical aptasensor for the detection of Salmonella enterica serovar typhimurium (STM) by immobilizing the single-stranded DNA (ssDNA) aptamer on the nanocomposite-coated glassy carbon electrode (GCE). The developed ssDNA/rGO–Nf sensing platform can reproducibly detect S. typhimurium with a detection limit of 10¹ cfu mL⁻¹ and requires only 1–2 μl of bacteria contaminated sample. The electrochemical aptasensor was also effective in assessing the specificity of the aptamer against different types of bacteria, indicating the developed platform can be used to specifically screen Salmonella bacteria from food samples in 10 min. Besides, the changes in electronic properties due to transduction of electrons after the interaction of the biorecognition element and the bacterial target were also characterized using photoluminescence spectroscopy (PL) in the study. These findings suggest the potential of developing high performance graphene-related sensors for food safety applications.