Chemically modified graphene and nitrogen-doped graphene: Electrochemical characterisation and sensing applications

•Characterisation of graphene, N-doped graphene, acid/base functionalised derivatives.•N-doping superior to time-consuming functionalisation procedures.•N-doped graphene with redox or conducting polymer composites characterised.•Electrocatalysis of enzyme cofactors FAD+ and NADH2, by N-doped graphene.

Functionalised graphene (G) and nitrogen doped graphene (NG) nanomaterials are excellent candidates for electrocatalytic sensing of biomolecules and for developing biosensors, due to their unique physicochemical and electronic properties. Electrochemical characterisation and comparison of basic or acidic functionalised G and NG has been carried out, as well as of composite materials based on NG with the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and the redox polymer poly(neutral red) by cyclic voltammetry and electrochemical impedance spectroscopy. Electroactive areas and heterogeneous electron transfer constant, of the GCE modified with the graphene derivatives have been evaluated, in order to choose the best material for electrode modification. The NG modified GCE enabled excellent electrocatalytic regeneration of the enzyme cofactors β-nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD), underlining the applicability of NG for the development of new sensitive biosensors.

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