3D-printed poly-ε-caprolactone/bioglass and iron disulfide composite materials for hard tissue engineering

3D printing has transformed scaffold production by enabling customizable, reproducible structures essential for effective bone tissue engineering. Therefore, the aim of this study was to obtain a series of 3D-printed structures consisting of bioglass (BG), whose bioactive properties support direct bonding with bone via a hydroxyapatite layer, and iron disulfide (FeS₂), used in traditional Chinese medicine for promoting bone tissue formation, fracture healing, and pain alleviation. The BG 47S6 was obtained through the sol-gel method, while the iron disulfide nanoparticles were produced via a microwave-assisted solvothermal treatment. The powders were characterized through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, and scanning electron microscopy (SEM). The diffractogram for the 47S6 BG demonstrated the crystallization of SiO₂ and C₂S phases alongside the typical amorphous phase of BG, while the iron disulfide nanoparticles displayed both pyrite (cubic) and marcasite (orthorhombic) mineral phases. The FT-IR spectrum of 47S6 BG showed characteristic bands corresponding to Si–O–Si and P–O. SEM images revealed irregular particle aggregates with an interconnected structure, while the FeS₂ particles appeared agglomerated, suggesting the coalescence of multiple crystallites during synthesis. Subsequently, the powders were mixed in varying proportions (100, 99, 97, and 95 wt% BG) and incorporated into a polycaprolactone (PCL) solution to create pastes for 3D printing. The scaffolds were printed with different parameters to optimize string thickness and porosity, and their morphology, mechanical properties, bioactivity, and biocompatibility were evaluated. Results demonstrated uniform scaffold fabrication and enhanced bioactivity. Notably, the addition of FeS₂ improved mechanical strength by preventing scaffold rupture, increased cell viability, and reduced oxidative stress, as confirmed by MTT and LDH assays using the hFOB 1.19 human preosteoblast line. Thus, the scaffolds fabricated in this study demonstrated significant potential for bone tissue engineering, opening new perspectives for developing advanced materials in regenerative medicine.