Manufacturing and mechanical characterization of PLA/cHAP/rGO composite for bone implants

At present, medicine is influenced by branches of engineering such as tissue engineering, bioengineering, materials engineering, among others; This is because the human body is made up of systems that activate or receive mechanical energies. The construction of grafts for bone regeneration, for example, is an area where engineering contributes greatly to medicine. These grafts must not only have a chemical and physical structure similar to the absent tissue, but they must also have adequate mechanical properties to continue to perform their functions in the system.

Bone reconstruction grafts are made up of scaffolds that resemble the porosity that human bone must have for blood flow and nutrients for cell growth. Furthermore, these scaffolds must have mechanical properties to support the various loads to which the bone structures are subjected.

One of the most used modern technologies for scaffolding 3D printing is material extrusion additive manufacturing (MEAM), which can process materials such as RGOlactic Acid (PLA), among others. The MEAM allows to control the mechanical properties of the scaffolds with the configuration of the printing parameters, such as porosity, layer thickness, space between filaments, screen angle and the external geometry of the pieces.

Taking into account the above, this research delves into the development and characterization of tailored PLA/cHAP/rGO composites, a novel class of biomaterials with the potential for bone implant applications. The study comprises several interconnected components, each contributing to the comprehensive assessment of these composites.

The initial phase involves the formulation of these composites, where synthetic polymeric materials, namely PLA, calcium hydroxyapatite (cHAP), and reduced graphene oxide (rGO), are combined in various ratios to achieve a range of material properties. The subsequent creation of 3D-printable filaments from these composite formulations opens the door to versatile and cost-effective scaffold fabrication methods using additive manufacturing techniques.

The heart of this research lies in the production of 3D scaffold models, incorporating gyroid and Schwartz primitive lattice structures, both pivotal in influencing the mechanical and structural characteristics of the resulting scaffolds. Through meticulous characterization techniques such as Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and thermal analysis, the compositional, structural, and thermal attributes of these composites are thoroughly examined.

Mechanical characterization follows, with an emphasis on modulus of elasticity, ultimate tensile strength, and compressive strength. These mechanical properties are of paramount importance, as they closely mimic those of human cortical bone, positioning the composites as promising candidates for load-bearing applications in tissue engineering and biomedicine.

Additionally, this research explores the in vitro degradation behaviour of these composites, particularly in a simulated physiological medium (PBS). The study reveals the tunability of the composites' degradation rates through matrix and rGO concentration adjustments, paving the way for controlled biodegradation in various biomedical scenarios.

Simulation and experimental validation further enhance our understanding of the mechanical behaviour of PLA/cHAP/rGO composites, offering predictive modelling capabilities that streamline biomaterial design and reduce the need for extensive experimental iterations. Lattice selection emerges as a crucial factor, influencing degradation profiles and mechanical properties.

In conclusion, this research advances the field of biomaterials by introducing tailored PLA/cHAP/rGO composites and novel scaffold fabrication methods, providing insights into degradation control, and offering potential applications in bone implants and tissue engineering. This work sets the stage for future biomaterial advancements and clinical use, ultimately benefiting patients in need of advanced medical implants.