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-MoS 2 -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 MoS 2 under illumination. Transmission electron microscopy revealed that AuNPs are uniformly dispersed on the MoS 2 -rGO/PI electrode surface with a diameter ~10   nm. X-ray photoelectron spectroscopy indicated that a strong binding force exists between reduced AuNPs and monolayer MoS 2 . The AChE modified AuNPs-MoS 2 -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-MoS 2 -rGO/PI film biosensor shows a linear response over a concentration range 0.005–0.150   μg/mL, a sensitivity of 4.44 uA/μg/   mL, a detection limit of 0.0014   μg/mL, acceptable reproducibility and stability to paraoxon. The flexible film biosensor has also proved used for detection of paraoxon in real samples.