Simultaneous voltammetric determination for DA, AA and NO₂⁻ based on graphene/poly-cyclodextrin/MWCNTs nanocomposite platform.

In the present work, graphene sheets (GS) and multiwall carbon nanotubes (MWCNTs) were dispersed in the mixed solution of cyclodextrin (CD) and cyclodextrin prepolymer (pre-CD) and were used as modifier to fabricate chemical modified electrode to simultaneous detect dopamine (DA), ascorbic acid (AA) and nitrite (NO2(-)). CD cross-linked pre-CD (CDP) displays excellent film forming ability, which made the electrode stable. Comparing with CDP-GS, CDP-MWCNTs and CDP-GS-MWCNTs modified electrodes, the CDP-GS-MWCNTs displays higher catalytic activity and selectivity toward the oxidation of DA, AA and NO2(-), revealing that MWCNTs effectively inhibited the stacking of individual GS and enhanced the utilization of GS based composites. The host-guest chemical reaction ability of CD and π-π stacking interaction between detected molecules and GS-MWCNTs surface were considered as the main reasons of the successfully simultaneous detection of DA, AA and NO2(-). Cyclic voltammetry (CV), scanning electron microscopy (SEM) and different pulse voltammetry (DPV) were employed to characterize the biosensor. The linear response range for AA, DA and NO2(-) were 5 μM-0.48 mM, 0.15-21.65 μM and 5 μM-6.75 mM, respectively and the detection limits were 1.65 μM, 0.05 μM and 1.65 μM.