Optimization of PVDF-TrFE Based Electro-Conductive Nanofibers: Morphology and In Vitro Response

Abstract

In this study, morphology and in vitro response of electroconductive composite nanofibers were explored for biomedical use. The composite nanofibers were prepared by blending the piezoelectric polymer poly(vinylidene fluoride-trifluorethylene) (PVDF-TrFE) and electroconductive materials with different physical and chemical properties such as copper oxide (CuO), poly(3-hexylthiophene) (P3HT), copper phthalocyanine (CuPc), and methylene blue (MB) resulting in unique combinations of electrical conductivity, biocompatibility, and other desirable properties. Morphological investigation via SEM analysis has remarked some differences in fiber size as a function of the electroconductive phase used, with a reduction of fiber diameters for the composite fibers of 12.43% for CuO, 32.87% for CuPc, 36.46% for P3HT, and 63% for MB. This effect is related to the peculiar electroconductive behavior of fibers: measurements of electrical properties showed the highest ability to transport charges of methylene blue, in accordance with the lowest fibers diameters, while P3HT poorly conducts in air but improves charge transfer during the fiber formation. In vitro assays showed a tunable response of fibers in terms of viability, underlining a preferential interaction of fibroblast cells to P3HT-loaded fibers that can be considered the most suitable for use in biomedical applications. These results provide valuable information for future studies to be addressed at optimizing the properties of composite nanofibers for potential applications in bioengineering and bioelectronics.

Keywords: composites; electroconductive; electrospinning; nanofibers.

Figure 1

Different PVDF-TrFE electrospun fibrous membranes with electroconductive phases: qualitative evaluations.

Figure 2

Comparison of pure and composite PVDF-TrFE nanofibers: SEM and EDS analysis.

Figure 3

Quantitative evaluation of pure and composite PVDF-TrFE nanofibers’ fiber diameters via image analysis.

Figure 4

Electrical characterization of pure and composite PVDF-TrFE nanofibers: Current–voltage (I–V) curves as a function of different active components used.

Figure 5

Comparative in vitro studies of PVDF, P3HT, MB, CuPc, and CuO electrospun fibers: cytotoxicity tests. All the results were normalized with respect to the positive control (TCP) representing the 100% of cell viability. (* p < 0.05).

Figure 6

Confocal microscopy of L929 cells’ adhesion after 24 h, onto electrospun fibers of PVDF-TrFE loaded with P3HT (a), MB (b), and CuPc (c). The images (Scale bar: 250 μm) were obtained by staining cells via Cell-Tracker Green CMFDA.

Figure 7

Cell proliferation of L929 cells seeded onto PVDF composites of P3HT, MB, and CuPc electrospun fibers. (* p < 0.05; ** p < 0.01). All the results were normalized with respect to PVDF fibers used as positive control.