Graphene Enhanced Electron Transfer at Aptamer Modified Electrode and Its Application in Biosensing

Graphene (GN), a two-dimensional and one-atom thick carbon sheet, is showing exciting applications because of its unique morphology and properties. In this work, a new electrochemical biosensing platform by taking advantage of the ultrahigh electron transfer ability of GN and its unique GN/ssDNA interaction was reported. Adenosine triphosphate binding aptamer (ABA) immobilized on Au electrode could strongly adsorb GN due to the strong pi-pi interaction and resulted in a large decrease of the charge transfer resistance (R-ct) of the electrode. However, the binding reaction between ABA and its target adenosine triphosphate (ATP) inhibited the adsorption of GN, and R-ct could not be decreased. On the basis of this, we developed a new GN-based biosensing platform for the detection of small molecule ATP. The experimental results confirmed that the electrochemical aptasensor we developed possessed a good sensitivity and high selectivity for ATP. The detection range for ATP was from 15 x 10(-9) to 4 x 10(-3) M. The method here was label-free and sensitive and did not require sophisticated fabrication. Furthermore, we can generalize this strategy to detect Hg2+ using a thymine (T)-rich, mercury-specific oligonucleotide. Therefore, we expected that this method may offer a promising approach for designing high-performance electrochemical aptasensors for the sensitive and selective detection of a spectrum of targets.