PHYSICOCHEMICAL CHARACTERIZATION OF HIGH β-TCP CONTENT POLYMERIC COMPOSITE FOR 3D-PRINTED BONE SCAFFOLDS: INVESTIGATING THE EFFECT OF CALCIUM PHOSPHATE COATING ON COMPOSITE PROPERTIES UNDER SIMULATED PHYSIOLOGICAL CONDITIONS

The use of commercial medical-grade biomaterials is an essential requirement for moving a lab-based technology to a higher Technology Readiness Levels. Over the past decade, a greater range of Good Manufacturing Practice-manufactured biomaterials of different formulations has become available, including material in filament form specifically for Fused Deposition Modelling 3D printing. Composites with high bioceramic content are beneficial for scaffold-guided bone regeneration due to their potential to enhance biological performance. However, 3D printing of composites with a high bioceramic phase (> 20%) remains challenging, as it negatively impacts both the accuracy and speed of the printing process. A common approach to further improve the bioactivity of bone scaffolds is surface modification through the deposition of calcium phosphate (CaP) layer. However, there is limited research on how such coatings affect the mechanical properties of the material under simulated physiological conditions. This study aims to characterize the physicochemical properties of 3D printed scaffolds fabricated from a medical-grade 60/40 blend of Lactoprene® 7415 and β-tricalcium phosphate, both before and after CaP deposition. This study optimized the 3D printing process to manufacture solid samples that accurately represent the bulk material properties. FTIR analysis was performed to investigate the molecular interactions between the composite material and water molecules, while DSC was used to assess the thermal properties of the material. A subset of the samples was then coated with CaP. All samples were subjected to uniaxial compression testing according to ASTM D695-23 standards under simulated physiological conditions to evaluate the impact of the CaP coating on the mechanical properties. The coating was characterized in terms of morphology, thickness, and weight. Additionally, water absorption and recovery behaviour were evaluated for both coated and uncoated groups. The results showed that a uniform coating was formed on the composite surface and improved water absorption, which impacted the mechanical properties of the composite and reduced the compressive modulus from 11.3 MPa to 6 MPa when exposed to simulated physiological conditions. However, the compressive performance of both groups under simulated physiological conditions demonstrated highly elastic behaviour, with a 90% recovery after compression. The study also revealed that water molecules can induce plasticization by modifying the thermal and chemical properties under physiological conditions. The composites exhibit advantageous physicochemical properties for scaffold-guided bone regeneration, together with a high ceramic content that could benefit the biological performance in future in vivo assessments. Such scaffolds are, therefore, promising candidates for bone tissue engineering.