Thermal Annealing Enhances Piezoelectricity and Regenerative Potential of PVDF-TrFE Nanofiber Scaffolds

Abstract

This study investigates bioelectric stimulation's role in tissue regeneration by enhancing the piezoelectric properties of tissue-engineered grafts using annealed poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) scaffolds. Annealing at temperatures of 80, 100, 120, and 140 °C is assessed for its impact on material properties and physiological utility. Analytical techniques such as Differential Scanning Calorimetry (DSC), Fourier-Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD) reveal increased crystallinity with higher annealing temperatures, peaking in β-phase content and crystallinity at 140 °C. Scanning Electron Microscopy (SEM) shows that 140 °C annealed scaffolds have enhanced lamellar structures, increased porosity, and maximum piezoelectric response. Mechanical tests indicate that 140 °C annealing improved elastic modulus, tensile strength, and substrate stiffness, aligning these properties with physiological soft tissues. In vitro assessments in Schwann cells demonstrate favorable responses, with increased cell proliferation, contraction, and extracellular matrix attachment. Additionally, genes linked to extracellular matrix production, vascularization, and calcium signaling are upregulated. The foreign body response in C57BL/6 mice, evaluated through Hematoxylin and Eosin (H&E) and Picrosirius Red staining, shows no differences between scaffold groups, supporting the potential for future functional evaluation of the annealed group in tissue repair.