Piezoelectric nylon-11 nanoparticles with ultrasound assistance for high-efficiency promotion of stem cell osteogenic differentiation.

Stem cell differentiation plays a significant role in tissue repair and regeneration. The interaction between stem cells and physical signals mediated by materials has significant influence on the fate of stem cells. The utilization of the stimulation originating from material physical properties to promote stem cell differentiation is being developed and has attracted much attention. However, it is difficult to induce electric signals into tissues noninvasively. In this study, piezoelectric nylon-11 nanoparticles (nylon-11 NPs) with uniform morphology were synthesized in mass production by a simple anti-solvent method. The prepared nylon-11 NPs possessed efficient piezoelectricity and high cytocompatibility. Fluorescent OPDA-coated nylon-11 NPs could image dental pulp stem cells (DPSCs) well, which demonstrated that nylon-11 NPs can be endocytosed easily by DPSCs. With the assistance of ultrasound, nylon-11 NPs could promote the osteogenic differentiation of DPSCs efficiently in a noninvasive way. Meanwhile, nylon-11 NPs could also promote the osteogenic differentiation of DPSCs to a certain extent. Therefore, piezoelectric nylon-11 NPs with the assistance of ultrasound will have enormous potential in tissue engineering, especially in stem cell fate regulation by noninvasive stimulation. This indicates that nanomaterial-mediated physical signals can regulate stem cell differentiation efficiently.