Acetylcholinesterase modified AuNPs-MoS2-rGO/PI flexible film biosensor: Towards efficient fabrication and application in paraoxon detection

A flexible acetylcholinesterase (AChE) film biosensor, based on a AuNPs-MoS2-reduced graphene oxide/polyimide flexible film (rGO/PI) electrode, has been synthesized for paraoxon detection. In this study, the rGO/PI film acts as the flexible substrate and AuNPs are reduced by monolayer MoS2 under illumination. Transmission electron microscopy revealed that AuNPs are uniformly dispersed on the MoS2-rGO/PI electrode surface with a diameter similar to 10 nm. X-ray photoelectron spectroscopy indicated that a strong binding force exists between reduced AuNPs and monolayer MoS2. The AChE modified AuNPs-MoS2-rGO/PI flexible film biosensor is used to hydrolyze acetylcholine chloride and obtain a large current response at 0.49 V by differential pulse voltammetry, demonstrating successful immobilization of AChE. In view of the inhibition of paraoxon on the AChE, under optimal conditions, the AChE/AuNPs-MoS2-rGO/PI film biosensor shows a linear response over a concentration range 0.005-0.150 mu g/mL, a sensitivity of 4.44 uA/mu g/ mL, a detection limit of 0.0014 mu g/mL, acceptable reproducibility and stability to paraoxon. The flexible film biosensor has also proved used for detection of paraoxon in real samples. (C) 2019 Published by Elsevier B.V.