Fabrication and characterization of additively manufactured CNT-bioglass composite scaffolds coated with cellulose nanowhiskers for bone tissue engineering

Abstract

During the fabrication of scaffolds for bone regeneration, it is difficult to concurrently achieve bioactivity, mechanical performance, and ease of fabrication. Additionally, implant surface functionalization is a topic of intense research to improve bone-to-implant interaction and augment bone repair. Accordingly, this study reports additively manufactured (AM) 45S5 Bioglass scaffolds reinforced with functionalized multi-walled carbon nanotubes (CNTs) that were dip-coated with cellulose nanowhiskers (CNWs). Carboxymethyl cellulose (CMC) was used as an ink carrier that showed suitable shear thinning behavior. The fabricated scaffolds were characterized using x-ray diffraction (XRD), Fourier transforms infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), and energy dispersive x-ray spectroscopy (EDS). 45S5 Bioglass reinforcement with CNTs and coating with CNWs led to an increase in the compressive strength from 20.5 to 27 MPa (∼32% enhancement), while the toughness increased from 2.08 to 3.92 MJ/m3 (∼88% enhancement). Additionally, structural analysis based on microcomputed tomography images showed that the AM-fabricated scaffolds exhibited suitable porosity, pore size, pore throat size, and interconnectivity. Moreover, the coating of the scaffold with CNWs increased the surface roughness, which may aid in bone cell attachment on the scaffold surface. Finally, these scaffolds were found to be bioactive, as revealed by in vitro studies in simulated body fluid (SBF). These results show the potential for efficient fabrication of hybrid scaffolds with controlled structure, bioactivity, and required toughness as well as strength for bone tissue engineering.