Visible Periodic Piezoelectric Domains in Silk Fibroin for Neurite-Orientated Extension.

The development of visible periodic piezoelectric domains is highly attractive but challenging to overcome the homogeneous distribution and lack of visualization of the electric field on traditional piezopolymers. This work reports an in situ synthesis to create customized silver patterns with micron-level distinguishability. This method serves to form visible periodic piezoelectric domains and endows the silk fibroin (SF) piezoelectric generator with maximum root mean square current, energy density, and voltage of 5.1 mA, 6.7 Wm and 529.5 mV, respectively, under an ultrasound intensity of 1.0 Wcm. The oriented piezoelectric electric field is periodically distributed into the SF film with ultrasound-driven assistance and remarkably regulates neurite directional growth, length, and gene expression. Additionally, these piezoelectric domains enable the direct and timely observation of the electric field's effect on neurites by biological microscopy. This approach paves the way for great potential in tailored electric stimulation for cell biology and medical engineering.