Scaffolds tridimensionais de P(VDF-TrFE)/BaTio3 produzidos por near-field electrospinning

Abstract

Functional three-dimensional structures, or scaffolds, are of great interest in the area of tissue engineering associated with regenerative medicine, as they allow the mimicry of biological structures. The electrospinning technique, considered a simplified and low-cost process, presents versatility in producing structures with high porosity and surface area, which allows interaction between cell materials at the molecular level. Scaffolds synthesized from piezoelectric materials, when subjected to electrical and/or mechanical forces, can stimulate cell growth and differentiation in specific tissues such as bones. Recent studies have indicated that the copolymer polyvinyl fluoride trifluoroethylene (PVDF-TrFE) associated with ceramic Barium Titanate (BaTiO3) has biological properties that are inspired by electronic characteristics owing to their high piezoelectric, pyroelectric, and ferroelectric responses. Thus, this work studies functional scaffolds with suitable characteristics for use in the area of tissue regeneration, from the development of an equipment that associates the direct-write near-field electrospinning (NFES) technique with the three-dimensional printing technique. The prototype allows the development of three-dimensional structures from fibers with suitable properties that mimic an electrophysiological environment, providing the formation/regeneration of biological tissue. The structural, physicochemical, and electrical characterizations of the material were carried out at the Universidade Federal de Itajubá (UNIFEI) - Itajubá, including scanning electron microscopy (SEM), surface wettability, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), solution viscosity, X-ray diffraction (XRD), impedance, and surface potential of the scaffolds. Biological characterization of the material was performed using in vitro studies to evaluate the proliferation, collagen, and cell behavior of the scaffold. For this, we used osteoblast-like MG-63 cells seeded on NFES and CES scaffolds. This work was conducted jointly with the AGH University of Science and Technology, Poland. Together with Biological Tests, the piezoresponse of the fibers was analyzed. The microstructure results showed the fibers diameter of 341 nm and 2,69 μm for CES and NFES scaffolds, respectively. The wettability assay demonstrated that the surface was hydrophobic, with contact angle of 115,6° for the CES scaffold and 100,6° for the NFES scaffold. Regarding physicochemical tests, the thermal stability of both materials was up to 440 °C, and the crystallinity of the CES scaffold corresponds to 79,63 % with a β phase content of 78,23. In contrast, the crystallinity of the NFES scaffold corresponds to 65,10% and presents 78,03% of β phase content. The XRD and FTIR analyses indicated that the absorption peaks and diffraction peaks of the membrane and scaffold characterized both materials as piezoelectric owing to the strong presence of the β phase, independent of the technique used to obtain the scaffolds. PFM analysis of both scaffolds showed fibers with piezoresponse properties superior to the bone tissue (NFES piezoresponse potential = 4.873 ± 0.637 mV; CES piezoresponse potential = 2.728 ± 0.411 mV; bone piezoresponse potential = ≈ 300 μV). These findings imply that the both scaffolds could mimic an electrophysiological environment that allows cell growth and proliferation. Biological findings showed good compatibility with cells and both scaffolds, and we noted that the proliferation and cell alignment follow the fiber pattern for NFES scaffolds.