Cellular Response to Ferroelectric PVDF-TrFE Nanoscale Surfaces Formed by Varying Polymer Concentration

Poly[(vinylidenefluoride-co-trifluoroethylene] [PVDF(TrFE)], a ferroelectric polymer capable of undergoing strain of up to 7% is both highly chemically resistant and has the advantage of being cytocompatible. Here we present a preliminary study into the response of mesenchymal stem cells to spin-coated PVDF(TrFE) films and examine how the polymer concentration influences electrophysical film properties and cell adhesion. Surface characterization was quantitatively assayed in terms of topography, roughness, wettability and chemistry, while the ferroelectric response of the films was confirmed via electrical probing of the polarization-field hysteresis. At the micron- and nanoscale scale, AFM analysis revealed that PVDF(TrFE) exhibited increased roughness and topographical features with increasing PVDF(TrFE) concentration. PVDF(TrFE) films displayed higher contact angles compared with control glass substrates, as indicated by wettability assay, yet elemental composition was unchanged. Electric field/polarization response analysis revealed films required bias voltages of up 100 v to undergo saturated polarisation hysteresis. Mesenchymal stem cells were cultured on PVDF(TrFE) films for up to 7 days, and assessed by morphometric analysis, focal adhesion quantification and real-time PCR. Cells grown on films formed from 3% w/v PVDF(TrFE) solutions exhibited significantly higher expression of FAK and focal adhesion reinforcement following 1 day of culture, indicating nanoscale roughness in PVDF(TrFE) films as a potent modulator of MSC adhesion to ferroelectric polymers.