Additive manufactured biodegradable and biocompatible polymeric nanocomposite scaffolds for bone tissue engineering applications

Abstract

In this thesis, the focus is on using the fused deposition modeling (FDM) method to manufacture functional biodegradable nanocomposite Polymeric Bone Tissue Scaffolds (PBTS). PBTSs are complex products, which have attracted significant attention in the literature in recent decades. In this study, a commercial and user-friendly FDM manufacturing technique was used to fabricate Polycaprolactone (PCL)/Nano-Hydroxyapatite (nHA)/Chitin-Nano-Whisker (CNW) nanocomposite scaffolds with advanced geometrical designs. The fabricated scaffolds were developed to have functional mechanical, biological, and biodegradation properties. Multiple stages of experimental, numerical, and analytical analyses were performed to achieve these goals. The scaffolds were manufactured in Triply Periodic Minimal Surfaces (TPMS) designs. The impacts of the advanced biomimetic designs, porosity, and biodegradation on the mechanical and morphological properties of the scaffolds were investigated. The nanocomposite filaments for the FDM method were produced using green manufacturing methods. The manufactured novel FDM filaments were characterized using Thermo-Gravimetric Analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR) to ensure the precision of the nanocomposite contents. The FDM processing conditions of the novel nanocomposite filaments were optimized using Taguchi’s orthogonal array experimental design method to achieve the optimal mechanical properties and structural integrity. The 3D printed nanocomposite bone tissue scaffolds were characterized to assess their mechanical and biological properties. The biodegradation rates of the 3D printed Gyroid-designed nanocomposite PBTSs were estimated in sixty weeks of biodegradation, employing numerical, and experimental results. Machine learning methods were used to connect the independent experimental and numerical results and extract objective functions to model properties of the 3D printed nanocomposite PBTSs. Multi-objective optimization was performed to propose non-dominated optimal options for the PBTSs porosity and the nanocomposite fillers percentages. The results indicated that the proposed green manufacturing method successfully fabricated the nanocomposite FDM filaments with high precision. The FDM printed PCL/nHA/CNW nanocomposite PBTSs with Gyroid structure have high mechanical properties in the practical range of bone tissue scaffolds, enhance cell proliferation and attachment to the scaffolds and biodegrade in the practical period for PBTSs. The multi-objective optimization method presents a few significant non-dominated optimal options, which can be selected based on the consumer’s priorities.