A built-in electric field with nanoscale distinction for cell behavior regulation

To mimic the electrical properties of collagen fibrils on a bone surface, a built-in nanoscale electric field is formed on the surface of a polypyrrole (PPy) coating-decorated potassium-sodium niobate (KNN) piezoceramic. With the fabrication strategy, the piezoelectricity of KNN after polarization results in the formation of an electric field on the surface, which could be regulated by adjusting the polarization process. Then, conductive PPy nanoarrays (CPNAs) are obtained on the surfaces of the KNN piezoceramics. The conductive PPy transports the electric field to the coating surface, and the nanoarray morphology results in variations in the surface potential, leading to a built-in nanoscale electric field. Biological characterization indicates that CPNAs exhibit acceptable biocompatibility. Moreover, the nanoscale electric field regulates cell behavior, and the relatively high surface potential promotes cell proliferation, cell attachment and osteogenic differentiation.