Abstract:
With increased awareness of nutrition and the advocacy for healthier food choices, there
exists a great demand for a simple, low-cost, label free and easy-to-use assays that can
reliably detect toxins in agriculture products. In this regard, a simple and highly
sensitive electrochemical sensing platform based on the structural switching signaling
of aptamer has been developed for the detection of smaller molecules using Ochratoxin
A as a model analyte. Pencil electrode was first modified with highly conductive
Graphene oxide/Fe3O4NP/PPY composite and then was self-assembled with aptamer
using EDC/NHS technique. This immobilized nanoprobe provided gates of tunnels for
the effective electron flow showing higher peak current. The introduction of the target
analyte (OTA) triggered switching of the aptameric structure resulting in the decrement
of the redox current. This decrease was proportional to the analyte concentration, thus
featuring signal on/off strategy. This proposed transducing design showed a dynamic
linear range (10 pg/mL-200ng/mL) with Limit of detection and limit of quantification
of 5pg/mL and 40pg/mL respectively. We demonstrate this transducing design as a
general inexpensive and reproducible method to specifically detect a wide variety of
analytes by selecting a suitable biorecognation element. Real sample analysis was
performed for the real time approach and results collected are in agreement with
practical application.
