Fabrication of electro-active nano-trans surfaces to design label free electrochemical aptasensor for ochratoxin A detection

Abstract

The importance of developing multifunctional nanohybrid materials for sensing technologies is rising with the advent of nanotechnology. Herein, we present integration of a novel nanohybrid electro-active material in the construct of electrochemical aptasensor. Electrochemical aptasensor was based on the electroactive composite of fGO/ Fe3O4NP/PPY (functionalized graphene oxide/ iron oxide nanoparticles/ polypyrrole) and analyte specific DNA aptamer. The sensing architecture was relatively less complex, highly sensitive and multi-functional in design. The Pencil electrode was modified with fGO/Fe3O4NP/PPY to work as a multifunctional electrochemical transduction platform. The nano-transducer surface not only served as a conductive and immobilization support, but also functioned as an electrochemical signal generating probe. Ochratoxin A (OTA) was used as target analyte to demonstrate the working principle of the developed aptasensor. The introduction of the target analyte (OTA) on designed probe triggered switching of the aptameric structure resulting in the marked decrement of the redox current. This decrease was proportional to the analyte concentration, thus featuring signal on/off strategy. The aptasensors showed linear range of 10 pg/mL-200 ng/mL, limit of detection (LOD) and limit of quantification (LOQ) of 5 pg/mL and 40 pg/mL, respectively. Real sample analysis was performed in spiked wheat samples to demonstrate the real-life applicability of the designed aptasensor.