3D-Printed Multifunctional PLA Scaffolds with Polyvinylidene Fluoride, Hydroxyapatite, and 45S5 Bioactive Glass

Abstract

Polylactic acid (PLA) is a biodegradable polymer widely employed in biomedical applications. This polymer can also be applied in additive manufacturing to obtain complex morphologies, even when changes in some of its properties are considered, such as the presence of photoinitiators, additives, and other polymers commonly found in light-cured resins. In this case, since photocurable resin formulations are subjected to UV-induced crosslinking during the 3D printing process, their degradation behaviour may differ substantially from that of conventional thermoplastic PLA. In this study, multifunctional PLA-based composite scaffolds incorporating poly(vinylidene fluoride) (PVDF), hydroxyapatite (HAp), and 45S5 bioactive glass (BG) were fabricated via liquid crystal display (LCD) 3D printing using a gyroid architecture for bone tissue regeneration applications. The proposed composite combines a biopolymeric matrix with bioactive ceramic fillers and a piezoelectric polymer as an additional component in an innovative approach to promote synergistic structural, thermal, rheological, and functional effects due to the high biocompatibility and bioactivity of the HAp and BG, enhanced by the expected piezoelectricity of the PVDF. The printed scaffolds were characterised by X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, photopolymerisation kinetics, differential scanning calorimetry, rheological testing, compression testing, and Shore A hardness measurements. The results indicated that PLA remains predominantly amorphous after printing, while crystalline phases associated with PVDF and HAp were identified. Microstructural analyses revealed satisfactory dispersion of fillers within the polymer matrix. Spectroscopic analysis revealed significant intermolecular interactions and a β-phase content of PVDF close to 50%, which is relevant for piezoelectric functionality. The combination of bioactive ceramic fillers and an electroactive polymer within a gyroid architecture yields a versatile potentially electroactive scaffold platform with tunable properties, highlighting its possible applicability for advanced bone tissue engineering applications and providing a foundation for future biological investigations.