Desenvolvimento de scaffolds por manufatura aditiva, utilizando compósito de PLA/HA com a hidroxiapatita extraída da escama do pirarucu (arapaima gigas)

Abstract

Due to the challenges caused by fractures and traumatic injuries, multidisciplinary fields have continuously sought innovations in the development of biomaterials for clinical bone grafting applications. This dissertation proposes the fabrication of bone grafts (scaffolds) by additive manufacturing using polylactic acid/hydroxyapatite (PLA/HA) composites, in which the hydroxyapatite was extracted from the scales of the pirarucu (Arapaima gigas). Fresh (in natura) pirarucu scales were subjected to alkaline and thermal treatments at 650 °C (H650) and 700 °C (H700). The hydroxyapatite (HA) was characterized by thermogravimetric analysis (TGA/DTG), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). HA was incorporated as a filler into PLA filaments at concentrations of 0.5, 1.0, and 1.5 wt%. The filaments were characterized by FTIR, Raman spectroscopy, and SEM and were subjected to tensile testing. The scaffolds were modeled using Creo Parametric 11.0.0.0 Educational Edition software and fabricated with a Creality Ender 3 S1 Pro 3D printer. The specimens were evaluated by compression (ASTM D695-15) and flexural (ISO 178-19) tests. Thermogravimetric analysis revealed a maximum decomposition rate at approximately 321 °C. XRD analysis confirmed the formation of highly crystalline hydroxyapatite (88.53% and 90.36%) with carbonated hydroxyapatite phases, which was corroborated by FTIR (bands at 1439 and 1412 cm⁻¹) and Raman spectroscopy (bands at 1065, 1075, and 1087 cm⁻¹). SEM micrographs showed the formation of irregular hydroxyapatite particles with average sizes of 99.72 and 438.51 nm for samples H650 and H700, respectively. EDS analysis identified the presence of Ca, O, P, C, Na, and Mg. FTIR and Raman spectra of the filaments exhibited the characteristic PLA bands, together with traces of HA, indicating the formation of filaments with predominantly amorphous content. The mechanical characterization showed that the tensile strength of the developed filaments was comparable to that of commercial filaments. The addition of 1 wt% H650 resulted in a tensile strength of 60.26 MPa, whereas the incorporation of 0.5 wt% H700 achieved 49.63 MPa. The filaments initially exhibited a brittle fracture morphology, gradually developing a more ductile behavior as the HA content increased. FTIR, Raman, and SEM analyses of the scaffolds followed the same trends observed for the filaments, while the flexural and compressive tests yielded strengths of 20.49 MPa (SF0.5% H700) and 24.61 MPa (FF1% H700), respectively. The study successfully demonstrated the production of scaffolds using PLA/HA composite filaments.