Assembly of carbon nanotubes on a nanoporous gold electrode for acetylcholinesterase biosensor design

An electrochemical sensing platform based on assembly of carbon nanotubes on a nanoporous gold electrode is described for highly sensitive detection of organophosphate pesticides. The nanoporous gold film (NPG) electrode is fabricated by an alloying/dealloying process, which possess high electroactive surface area and is an excellent substrate for sensor design. The NPG functionalized with cysteamine allows the immobilization of carbon nanotubes on the electrode with the self-assembly technique. The carboxylated carbon nanotubes are further linkered with acetylcholinesterase (AChE) for amperometric sensing of pesticides. The immobilized AChE, as a model, shows excellent activity to its substrate and allows a quantitative measurement of organophosphate pesticides. Under the optimal experimental conditions, the inhibition of malathion is proportional to its concentration in the range of 0.001-0.5 mu g mL(-1) with a detection limit of 0.5 ng mL(-1). The proposed method shows good reproducibility and high stability, which provides a new avenue for electrochemical biosensor design. (C) 2014 Elsevier B.V. All rights reserved.