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

Abstract 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–NO 2 ) was fabricated by electrochemical reduction of nitrophenyl diazonium salt (N 2 + Cl − –Ph–NO 2 ). The GCE–Ph–NO 2 modified electrode was reduced to phenylamine-modified electrode (GCE–Ph–NH 2 ) by sodium borohydride/gold–polyaniline (NaBH 4 /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 (ERC 60 –GO–Ph–GCE) interface. The electrocatalytic activity of developed (ERC 60 –GO–Ph–GCE) interface originates from the synergetic effects of electrochemically reduced fullerene (ERC 60 ) and graphene oxide (ERGO) species that makes the conjugate (C 60 –GO) film highly conductive. The (ERC 60 –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 μM with a detection limit of 0.03 μM. The developed (ERC 60 –GO–Ph–GCE) interface shows good sensitivity that makes it suitable for detection of HVA in biological fluids (urine).