Polydopamine-functionalized graphene nanoplatelet smart conducting electrode for bio-sensing applications

Abstract

The development of a novel polydopamine (PDA)-functionalized graphene nanoplatelets (GNPs)-based disposable sensor is described. The sensor was fabricated by drop-coating PDA@GNPs in polyethylene glycol (PEG) and poly(3,4-ethylenedioxythiophene (PEDOT):poly(styrenesulfonate) (PSS) aqueous suspension onto the working area of a screen-printed electrode (SPE). The final sensor, designated as PDA@GNPs/PPP/SPE, was characterized by scanning electron microscopy (SEM), Raman spectroscopy, Faradaic electrochemical impedance spectroscopy (FEIS) and cyclic voltammetry (CV). Mediated detection of hydrogen peroxide (H2O2) via the redox properties of PDA was achieved. It showed excellent selectivity and sensitivity towards H2O2 with a limit of detection and sensitivity of 0.55 µM (S/N = 3) and 3.0 µA mM−1 cm−2, respectively. Thereafter, glucose oxidase (GOx) was immobilized onto the electrode to develop GOx/PDA@GNPs/PPP/SPE sensor. The glucose biosensor exhibited a limit of detection of 0.25 μM (S/N = 3) and a sensitivity of 0.51 μA μM−1 cm−2; thus, proving its potential suitability for bio-sensing applications. Keywords: Polyethylene glycol, Screen-printed electrodes, Bio-sensing, Mediated sensors, Thin films, Dopamine, Organocatalysts