Electrochemically reduced fullerene-graphene oxide interface for swift detection of Parkinsons disease biomarkers

We are reporting first-time synthesis of the novel water-soluble fullerene-graphene oxide (C-60-GO) conjugate by 1,3-dipolar cycloaddition reaction between fullerene (C-60) and azide functionalized graphene oxide (Go-N-3). The synthesized fullerene-graphene oxide (C-60-GO) conjugate was characterized by fourier transform infrared spectroscopy (FTIR), Ultraviolet-visible (UV-vis) spectroscopy, electrochemical and field emission electron microscopy (FESEM). The C-60-GO conjugate was immobilized on surface of glassy carbon electrode (GCE) using surface bound diazonium salts as an impact strategy. The nitrophenyl modified GCE (GCE-Ph-NO2) was fabricated by electrochemical reduction of nitrophenyl diazonium salt (N2+Cl--Ph-NO2). The GCE-Ph-NO2 modified electrode was reduced to phenylamine-modified electrode (GCE-Ph-NH2) by sodium borohydride/gold-polyaniline (NaBH4/Au-PANI) system. The surface phenylamine groups of GCE-Ph-NH2 were converted to diazonium groups (GCE-Ph-N2(+)Cl(-)) which upon electrochemical reduction in an aqueous C-60-GO conjugate solution causes successful immobilization of C-60-GO conjugate to give phenyl modified fullerene-graphene oxide interface (C-60-GO-Ph-GCE). The C-60-GO-Ph-GCE interface upon electrochemical reduction in 1.0 M potassium hydroxide (KOH) solution produces highly conductive electrochemically reduced (ERC60-GO-Ph-GCE) interface. The electrocatalyfic activity of developed (ERC60-GO-Ph-GCE) interface originates from the synergetic effects of electrochemically reduced fullerene (ERC60) and graphene oxide (ERGO) species that makes the conjugate (C-60-GO) film highly conductive. The (ERC60-GO-Ph-GCE) interface was applied for determination of the homovanilic acid (HVA; a biomarker for Parkinsons disease) over a concentration range from 0.1-7.2 mu M with a detection limit of 0.03 mu M. The developed (ERC60-GO-Ph-GCE) interface shows good sensitivity that makes it suitable for detection of HVA in biological fluids (urine). (C) 2016 Elsevier B.V. All rights reserved.