Manufatura aditiva de biocompósitos a partir de ácido poliláctico reforçado por hidroxiapatita e nanotubos de carbono para regeneração de tecido ósseo

Abstract

Bone tissue is one of the most important tissues in the human body. Unfortunately, some traumatic events can cause fractures that can lead to temporary or permanent disability. Scaffolds are some of the materials that help in the treatment of these fractures, as they play an important role in the bone repair process and can be manufactured by 3D printing. Polylactic acid (PLA), as it is biodegradable, is one of the materials used in the production of scaffolds. Furthermore, the association of PLA and hydroxyapatite (HA) in its manufacture has shown excellent results, accelerating bone regeneration and reducing healing time. Another promising material for making scaffolds are carbon nanotubes (CNT), which have excellent mechanical properties and also accelerate bone growth. Thus, the main objective of this study was to produce scaffolds by additive manufacturing from polylactic acid (PLA) reinforced with hydroxyapatite (HA) and carbon nanotubes (CNT), to be applied in the regeneration of bone tissue and characterized through mechanical and biological. Hydroxyapatite was synthesized by wet means and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), presenting phases characteristic of HA, characteristic groups and a morphology with a porous surface with varying particle sizes, important characteristics for a biomaterial. The pure PLA, PLA/HA and PLA/NTC scaffolds were produced by additive manufacturing with an opening between the walls of 1 mm and 2 mm and characterized through mechanical tests and biological tests. Furthermore, PLA/NTC scaffold samples were impregnated with HA on the surface by thermal and chemical treatment to evaluate the influence of ceramics on the composite surface. The micrograph of the scaffolds showed that the addition of CNT made the PLA surface rougher compared to the sample containing HA; The TGA curves suggested that temperature may favor the thermal stability of PLA/NTC scaffolds impregnated with HA on the surface; Ramam showed an interaction between hydroxyapatite on the CNT surface and a possible structural transformation of PLA/CNT; In compression tests, PLA/NTC scaffolds with an opening between the walls of 1 mm showed better compression resistance; In cell viability assays, fibroblasts incubated with pure PLA, PLA/HA and PLA/NTC scaffolds showed high viability after evaluation by the MTT assay for the two forms of preparation (heat treatment impregnation and chemical treatment impregnation and for the two openings between the walls. More than 85% of the cells remained viable after 48h of incubation with all scaffolds tested, with the groups that had NTC in their composition showing the best results, both for heat treatment (more than 95% of cell viability) as well as chemical treatment (acetone). Given the results presented, it is concluded that PLA scaffold reinforced with HA and CNT may be promising as a biomaterial used to aid in the regeneration of bone tissue, contributing to the reduction of time hospitalization of patients suffering from bone fractures.