Three-dimensional graphene nanosheet doped with gold nanoparticles as electrochemical DNA biosensor for bacterial detection

Abstract

Corrosion induced by sulfate-reducing bacteria (SRB) occurs in a wide variety of industry sectors. It is urgent to develop effective techniques for convenient detection of SRB in service environments and early diagnosis of the potential of microbial corrosion. Herein, a novel electrochemical DNA biosensor based on 3-dimensional graphene (3D G) hierarchical structure functionalized with Au nanoparticles (Au NPs) is developed, enabling detection of the dissimilatory sulfite reductase (DsrAB) gene from SRB with a good sensitivity and reliability, and proper selectivity. Various surface analysis techniques are used to characterize the morphology and composition of the 3D G-Au NP nanocomposite, and cyclic voltammetry is used to measure the electrochemical response of the nanocomposite biosensor to hybridization of a target DNA (TD). The improved performance of the developed biosensor is attributed to the large surface/volume ratio and good conductivity of the 3D G-Au NP hierarchical structure. Under optimized conditions, the biosensor shows a high sensitivity, with the detection limit up to 9.41×10−15 M of the TD. Moreover, the biosensor successfully detects the DsrAB DNA in the fluid collected from an oilfield, and shows an improved detection limit than both gel electrophoresis and the quantitative reverse transcription polymerase chain reaction methods.