DNA Electrochemical Aptasensor for Detecting Fumonisins B1 Based on Graphene and Thionine Nanocomposite

In this paper, a novel aptasensor was designed by with the dual amplification of Au nanoparticles (AuNPs) and graphene/thionine nanocomposites (GS-TH) for sensitive determination of fumonisins B-1 (FB1). AuNPs is modified at the electrode surface to increase the electrical conductivity and fabricate specific recognition interface for FB1 through the hybridization of capture DNA and its aptamer. Large number of TH molecules were loaded at the surface of graphene sheet to served as electrochemical probe and increase its electrochemical signal due to the excellent conductivity and large surface area of graphene sheet. This type of nanocomposites is then assembled to the single strand section of FB1 aptamer at electrode surface by pi-pi stacking interactions between them, leading to an enhanced electrochemical signal. After the specific combination between FB1 aptamer and its target (FB1) in solution, GS-TH was released from electrode surface, resulting in a decreased electrochemical signal. The result demonstrated that the decreased currents were proportional to the FB1 concentration in the range of 1-10(6) pg/mL with a detection limit of 1 pg/mL. Besides, the developed aptasensor was also applied successfully for the determination of FB1 in feed samples. The result shows this aptasensor has a higher sensitivity and selectivity.