ELECTROCATALYTIC OXIDATION OF TRYPTOPHAN AND TYROSINE USING DENSELY PACKED COBALT OXIDE SANDWICHED GRAPHENE STACKS MODIFIED ELECTRODE

Herein, we construct a novel non-enzymatic, simple, selective and sensitive determination of Tryptophan and
Tyrosine sensor. Cobalt oxide sandwiched graphene nanocomposite (COSG-NC) was successively synthesized
through self-assembly method and immobilized on the surface of the wax impregnated graphite electrode via a
simple drop and dry method. Surface topography of the densely packed COSG-NC electrode was confirmed by
atomic force microscope analysis. The fabricated modified electrode showed an exceptional electrocatalytic
response for Trp and Tyr oxidation occurred at a reduced overvoltage. Under optimal experimental conditions, the
COSG-NC modified electrode demonstrated the extensive determination range from 24 × 10-6 M to 1 × 10-3 M and
41 × 10-6 M to 1 × 10-6 M with low limit of detection in the range of 8.2 × 10-6 M and 13 × 10-6 M (S/N = 3) of Trp
and Tyr, respectively. The superior responses of the modified electrode for Trp and Tyr have mainly ascribed to the nanocomposites having large surface area with more electroactive sites of Co3O4 and synergistic effect of graphene nanocomposites. This work offered a reasonable approach for future research in enzyme-free amperometric sensors for biomolecules determination