Self-assembled diphenylalanine peptide microtubes covered by reduced graphene oxide/spiky nickel nanocomposite: An integrated nanobiomaterial for multifunctional applications

Highlights: • Peptide microtubes (PMTs) integrated with nickel nanoparticles-decorated rGO were for the first time fabricated. • rGO/Ni composite forms planar electrode-like layer on PMT surface and induces a 100-fold increase in electrical conductivity. • A two-fold increase in mechanical stiffness of the microtubes was revealed. • The appearance of a strong piezoresponse (with vertical and lateral piezo-coefficients of 12 pm/V and 18 pm/V) was found. In this work we report macroscopic integration of reduced graphene oxide decorated by nickel nanoparticles (rGO/Ni) with self-assembled diphenylalanine (FF) peptide microtubes (PMTs). The rGO/Ni nanocomposite forms planar electrode-like structure on the FF PMT surface and improves its mechanical and physical characteristics, as evidenced by the electron and scanning probe microscopy techniques. In particular, the enhancement of helical structural stability and stiffness of PMTs in the presence of rGO/Ni has been found. The interaction between rGO/Ni and FF PMTs modifies electromechanical properties of the microtubes, so that a large radial piezoresponse untypical of the pristine FF PMTs appears. Furthermore, the introduction of rGO/Ni enhances electrical conductivity of FF PMTs. The energy diagram of the PMT/rGO/Ni structure suggests an easy path for the optical conversion and light energy harvesting. The technical approach considered in this work opens up a new perspective for the fabrication of macroscopic-scale integrated rGO/Ni and FF PMTs allowing a variety of functional bio-nanostructures to be designed.