Highly sensitive and selective dopamine biosensor based on a phenylethynyl ferrocene/graphene nanocomposite modified electrode

A new ferrocene derivative (1-[(4-amino) phenylethynyl] ferrocene, Fc-NH2) was synthesized for the first time. The ferrocene derivative molecule contained the phenylethynyl skeleton, ferrocene and amino groups with excellent electrochemical properties. The graphene/Fc-NH2 nanocomposite was prepared by mixing graphene solution and Fc-NH2 solution in one pot and the nanocomposite was utilized to construct a Nafion/graphene/Fc-NH2 modified glassy carbon electrode (GCE). The ferrocene derivative immobilized on the graphene can enhance the charge-transport ability of the nanocomposite, stabilize the graphene and prevent the leakage of ferrocene. The detection signal of dopamine (DA) was significantly amplified on the Nafion/graphene/Fc-NH2/GCE. It was experimentally demonstrated that the signal enhancement results from the synergy amplification effect of graphene and the Fc-NH2. The oxidation peak currents of DA were linearly related to the concentrations in the range of 5 x 10(-8) to 2 x 10(-4) M with the detection limit of 20 nM in the absence of uric acid (UA) and ascorbic acid (AA). In the presence of 10(-3) M AA and 10(-4) M UA, the linear response range was 1 x 10(-7) to 4 x 10(-4) M, and the detection limit was 50 nM at S/N = 3. Using the proposed Nafion/Fc-NH2/graphene/GCE, DA was successfully determined in real samples with the standard addition method.