Ultrasound-activated piezoelectric P(VDF-TrFE)/boron nitride nanotube composite films promote differentiation of human SaOS-2 osteoblast-like cells.

Piezoelectric films of poly(vinylidenedifluoride-trifluoroethylene) (P(VDF-TrFE)) and of P(VDF-TrFE)/boron nitride nanotubes (BNNTs) were prepared by cast-annealing and used for SaOS-2 osteoblast-like cell culture. Films were characterized in terms of surface and bulk features, and composite films demonstrated enhanced piezoresponse compared to plain polymeric films (d ₃₁ increased by ~80%). Osteogenic differentiation was evaluated in terms of calcium deposition, collagen I secretion, and transcriptional levels of marker genes (Alpl, Col1a1, Ibsp, and Sparc) in cells either exposed or not to ultrasounds (US); finally, a numerical model suggested that the induced voltage (~20-60 mV) is suitable for cell stimulation. Although preliminary, our results are extremely promising and encourage the use of piezoelectric P(VDF-TrFE)/BNNT films in bone tissue regeneration.
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