α- and β-Poly(Vinylidene Fluoride) Evoke Different Cellular Behaviours

Abstract

α-Phase poly(vinylidene fluoride) (PVDF) has chains of zero dipole moments and is, therefore, nonpiezoelectric, while β-phase PVDF has the most significant piezoelectric properties among the polymorphs due to its polar chains. Although many reports describe PVDF as a suitable biomaterial due to its stability and biocompatibility, few considered the specific effects that the different polymorphs exert on cellular behaviour. We hypothesized that α- and β-phase PVDF will exert direct but different influences on cell attachment and metabolic activity. PVDF films were fabricated using N,N-dimethylformamide (DMF) and hexamethylphosphoramide (HMPA) by solvent casting. Samples were characterized by differential scanning calorimetry, Fourier transform infrared spectroscopy and X-ray diffraction. Films containing 83.5% α-phase PVDF (DMF-PVDFα) and 91.4% of β-phase PVDF (HMPA-PVDFβ within the crystalline regions were produced and used to evaluate in vitro attachment and metabolic activity of L929 cells. Cell metabolic activity on both PVDF conformations increased 3-fold over the 1-week culture period, with higher cell metabolic activity observed on DMF-PVDFα on day 5 of culture, compared to HMPA-PVDFβ. Cells grown on DMF-PVDFα were well-spread, flat and expressed spotted paxillin in focal adhesions that were mainly localized to perinuclear regions of the cells, while a high proportion of cells on HMPA-PVDFβ were bulging, round and expressed relatively fewer paxillin spots. Our results suggest that α-phase PVDF supports higher cell metabolic activity and better cell spreading compared to β-phase PVDF. Such variations can potentially be exploited for different biomedical applications.

Crystalline polymorphism in poly(vinylidenefluoride) membranes

“…Contrarily, Low et al [166] found that α phase PVDF supports higher cell metabolic activity and cell spreading compared to the β phase. Recently, it was found that interestingly β phase PVDF membranes can provide the necessary electrical stimuli for the growth and proliferation of special cells [167].…”

High-Performance Coils and Yarns of Polymeric Piezoelectric Nanofibers

“…Bulk PVDF has a failure strain in the range of 12% -50% 26, 27 . In addition, PVDF is biocompatible and is considered a highly attractive polymer for biomedical applications such as in smart catheter devices and as scaffold for tissue engineering 28,29,30 .…”

Effect of annealing process on the phase formation in poly(vinylidene fluoride) thin films

“…Spin coating was used to obtain thin films of β-Phase [11][12][13]. α and β-Phase conformation were produced in PVDF thin films cast by varying solvent polarity (DMF and HMPA) respectively, evaporation rate and drying temperature 140 o C [14]. By crystallization at temperatures near the melting temperature (T m ) of the α-Phase, the γ-Phrase may be outcome [8,[15][16].…”