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

Abstract

a b s t r a c tAn 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 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.

A novel acetylcholinesterase biosensor based on ionic liquids-AuNPs-porous carbon composite matrix for detection of organophosphate pesticides

“…Organophosphate pesticides (OPs) play an important role in increasing agricultural productivity due to their high insecticidal activity [1][2][3]. Unfortunately, owing to their high acute toxicity and bioaccumulation effect, the residue in the environment can cause long-term damage to human health [4].…”

Recent advances in biosensors based on enzyme inhibition

“…The use of nanocomposites allows for detecting the inhibitors at very low detection limit, but very often requires high potential, even higher than the sensor modified with only carbon nanotubes. The CNTs were also used as a link between the cysteamine immobilised onto nanoporous gold film electrode and AChE (Ding et al, 2014). As expected, the detection of substrate occurred at a high potential (the peak of thiocholine oxidation was observed at at 913 mV in cyclic voltammetry), however the developed biosensor leads to detect the malathion with a detection limit of 0.5 ppb.…”

Cholinesterase-based biosensors

“…Another possibility to reduce the applied potential is the using of novel materials such as carbon nanotubes [50][51][52][53][54][55][56] . Carbon nanotubes exhibit electrocatalytic activity toward thiocholine and possess high surface area.…”

“…Chauhan and Pundir immobilized AChE via covalent binding on Fe 3 O 4 nanoparticle/multi-walled carbon nanotube-modified indium tin oxide-coated glass plate for detection of malathion, chlorpyrifos, monocrotophos and endosulfan 52 . Ding et al designed an electrochemical sensing platform based on assembly of carbon nanotubes on a nanoporous gold electrode for sensitive detection of pesticides 50 . Kesik et al reported an amperometric biosensor based on a conducting polymer using multi-walled carbon nanotubes for detection of organophosphates.…”