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 (C₆₀–GO) conjugate by 1,3-dipolar cycloaddition reaction between fullerene (C₆₀) and azide functionalized graphene oxide (GO–N₃). The synthesized fullerene–graphene oxide (C₆₀–GO) conjugate was characterized by fourier transform infrared spectroscopy (FTIR), Ultraviolet–visible (UV–vis) spectroscopy, electrochemical and field emission electron microscopy (FESEM). The C₆₀–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 C₆₀–GO conjugate solution causes successful immobilization of C₆₀–GO conjugate to give phenyl modified fullerene–graphene oxide interface (C₆₀–GO–Ph–GCE). The C₆₀–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 electrocatalytic 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 (C₆₀–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 μM with a detection limit of 0.03 μM. The developed (ERC₆₀–GO–Ph–GCE) interface shows good sensitivity that makes it suitable for detection of HVA in biological fluids (urine).