Piezoelectric charge induced hydrophilic poly(L-lactic acid) nanofiber for electro-topographical stimulation enabling stem cell differentiation and expansion

Cell-traction driven electrical stimulation on piezoelectric nanofibers mediates cell behavior without chemical factors or external stimuli, indicating a promising therapy at cell level. Generally, surface modification is required to achieve favorable cell adhesion for efficient electromechanical signal transmission. Nevertheless, common modification methodologies either easily fade away or destroy the nanostructure of piezoelectric nanofibers. Herein, with the assistance of ultrasound activated surface charges, in situ hydrophilic modification on piezoelectric poly(L-lactic acid) nanofibers is first proposed for cell adhesion. Due to the electrostatic interaction between dopamine and activated piezoelectric nanofiber, the efficient and robust in situ modification is obtained without compromising the nanofibrous structure. Stimulated by the piezoelectric nanofibers with modification, neural stem cells differentiate significantly into nerve cells on day 7 without exogenous growth factors. To our knowledge, the effect of inducing stem cell differentiation far outperforms that in previous reports. In addition, it has been demonstrated that the level of both cell differentiation and directional expansion is consistent with that of cell adhesion condition regardless of the intensity of electrical cue. This connection of cell adhesion and electro-topographical stimulation effects may guide the efforts in the design of electroactive scaffolds.