Immobilization-free direct electrochemical detection for DNA specific sequences based on electrochemically converted gold nanoparticles/graphene composite film

Abstract

A direct electrochemical DNA sensor was constructed based on gold nanoparticles/graphene film. A precursor graphene film was fabricated on glassy carbon electrode (GCE) using both electrochemically reduced graphene oxide (ERGNO) and chemically reduced graphene oxide (CRGNO). The electrochemical approach was green and fast, and unlike chemical reduction, does not result in contamination of the reduced material, and at highly negative potential could reduce the oxygen functionalities (-OH, C-O-C and -COOH) of the graphene oxide more efficiently. ERGNO exhibited better electrochemical and electrocatalytic performances than CRGNO. Gold nanoparticles (AuNPs) were electrodeposited on the ERGNO/GCE to amplify the electrochemical signals. The resulting AuNPs/ERGNO composite film was characterized by scanning electron microscopy, energy dispersive spectroscopy and Raman spectroscopy. The electrochemical responses of guanine (G), adenine (A), thymine (T) and cytosine (C) were investigated at AuNPs/ERGNO/GCE, which showed more favorable electron transfer kinetics than at ERGNO/GCE, demonstrating the significantly synergistic electrocatalytic effect of ERGNO and AuNPs. Synthetic sequence-specific DNA oligonucleotides was successfully detected and the established immobilization-free biosensor had the ability to discriminate single-or double-base mismatched DNA.

Graphene-assisted dual amplification strategy for the fabrication of sensitive amperometric immunosensor

“…To increase the efficiency and sensitivity of the immunosensor, much attention is paid to the development of novel nanomaterials as labels, including metal nanoparticles, quantum dots and carbon nanotubes (Hansen et al, 2006;Rijiravanich et al, 2008). Recently, exfoliated graphene oxide (EGO) has been widely used in drug loading and delivery, optical and fluorescent DNA detection (Liu et al, 2008;Du et al, 2010b), owing to its large specific surface area (two accessible sides), abundant oxygen functional groups and high water solubility (Dreyer et al, 2010). However, the electric conductivity of EGO is much lower than reduced graphene, which limits its application in electrochemical immunosensor.…”

Simple approach for ultrasensitive electrochemical immunoassay of Clostridium difficile toxin B detection

“…One of the most popular strategies is enzyme functionalized nanoparticles used as tracers to enhance the sensitivity of detection by loading a large amount of enzymes (Du et al, 2011). Graphene oxide (GO), a novel oneatom thick and two-dimensional graphitic carbon system with abundant oxygen functional groups (Du et al, 2011;Sharma et al, 2013;Shao et al, 2010), have gained great interest and enormous attention in constructing electrochemical biosensors because of their unique structural features such as large specific surface area, physiological stability and good biocompatibility (Du M. et al, 2010;Fiorito et al, 2005). Thus, we employed GO as a nanocarrier for co-immobilizing enzyme and antibody by using the bioconjugates featuring horseradish peroxidase (HRP) and HRP-Tcd B linked to functionalized GO-COOH.…”

Graphene-modified Interdigitated Array Electrode: Fabrication, Characterization, and Electrochemical Immunoassay Application

“…Due to these great advantages, surface modification with GO/rGO is easily applied to many different materials. Recently, glassy carbon (GC), [4][5][6][7] pyrolytic graphite, 8 gold, 9,10 and indium tin oxide (ITO) 11 electrodes have been prepared with rGO-modified surfaces and their electrochemical properties were characterized. Functionalized materials based on rGO, such as Pt-nanoparticle hybridized rGO, 12 gold nanoparticle deposited rGO, 7 and nitrogen doped rGO, 13 have also been developed to modify electrodes and improve their electrochemical responses.…”