Investigation into morphological and electromechanical surface properties of reduced-graphene-oxide-loaded composite fibers for bone tissue engineering applications: A comprehensive nanoscale study using atomic force microscopy approach

•RGO flakes addition into 3D printed PCL fibers caused changes of surface-related properties.•Surface potential was locally several times higher for composite fibers in comparing with polymeric ones.•The addition of nanoflakes did not change hydrophobic nature of polycaprolactone.