Development of an automated flow-based electrochemical aptasensor for on-line detection of Ochratoxin A

The development of a fully automated flow electrochemical aptasensor based on the use of a selective capture aptamer and modified magnetic beads (MBs) is reported. The developed flow-based aptasensor is demonstrated under continuous/stopped flow conditions for the detection of ochratoxin A (OTA) employing direct and indirect competitive strategies. In the direct format, biotin labeled and free OTA competed to bind with immobilized aptamer onto the surface of a screen printed carbon electrode (SPCE) placed in a flow cell. In the indirect assay, immobilized OTA and free OTA in solution competed to bind with aptamer in solution. The current response obtained from the conversion of the substrate 1-naphtyl phosphate by ALP decreased proportionally to the concentration of OTA in the sample. A lower limit of detection (0.05 mu g/L) was obtained with the indirect flow-based aptasensor. Finally, the flow-based aptasensor was validated with real beer samples, and the good recovery values demonstrated the efficiency of the competitive aptasensor. (C) 2012 Elsevier B. V. All rights reserved.