Graphene adsorbed on silk-fibroin meshes: Biomimetic and reversible conformational movements driven by reactions

[Display omitted] •Graphene adsorbed on silk-fibroin meshes results in an electroactive material.•The graphene reduction/oxidation drives exchange of cations and water.•Stationary electrochemical responses include structural information.•Conformational packing/relaxation processes are identified. Graphene oxide has been uniformly adsorbed on silk-fibroin meshes and then chemically reduced to get a conductive, electroactive and very stable coating. Used as a self-supported working electrode in NaCl aqueous solution, the coated mesh supports the electrochemical characterization of the adsorbed graphene. Stationary voltammetric and chronoamperometric responses include structural information. The graphene reduction/oxidation drives the incorporation/expulsion of cations and water from the solution and the concomitant film swelling/shrinking. Rising oxidation charges give rising shrunk and conformational packed energetic states of folded oxidized graphene. Higher energies (higher overpotentials) are required to relax and unfold the graphene giving structural reduction-relaxation responses starting by nucleation through the less compacted points of the folded graphene sheets. Similar structural responses were attained from conducting polymers or carbon nanotubes. All of them mimic those processes taking place during biological reactions involving macromolecules as reactants and originating biological functions.