Biodegradable polymers and bioceramics give rise to composite structures that serve as scaffolds to promote tissue regeneration. The current research explores the preparation of biodegradable filaments for additive manufacturing. Bioresorbable segmented poly(ester urethanes) (SPEUs) are easily printable elastomers but lack bioactivity and present low elastic modulus, making them unsuitable for applications such as bone tissue engineering. Strategies such as blending and composite filament production still constitute an important challenge in addressing SPEU limitations. In this work, SPEU-poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) blends and SPEU-PHBV-Bioglass 45S5^® (BG) composite materials were processed into filaments and 3D structures. A comprehensive characterization of their morphology and thermal and mechanical properties is presented. The production of 3D structures based on SPEU-PHBV with excellent dimensional precision was achieved. Although SPEU-PHBV-BG printed structures showed some defects associated with the printing process, the physicochemical, thermal, and mechanical properties of these materials hold promise. The blend composition, BG content and particle size, processing parameters, and blending techniques were carefully managed to ensure that the mechanical behavior of the material remained under control. The incorporation of PHBV in SPEU-PHBV at 70:30 w/w and BG (5 wt%) acted as reinforcement, enhancing both the elastic modulus of the filaments and the compressive mechanical behavior of the 3D matrices. The compressive stress of the printed scaffold was found to be 1.48 ± 0.13 MPa, which is optimal for tissues such as human proximal tibial trabecular bone. Therefore, these materials show potential for use in the design and manufacture of customized structures for bone tissue engineering.

Resorbable microparticles can be added to hydrogel-based biocompatible scaffolds to improve their mechanical characteristics and allow localised drug delivery, which will aid in tissue repair and regeneration. It is well-known that bioprinting is important for producing scaffolds personalised to patients by loading them with their own cells and printing them with specified shapes and dimensions. The question is how the addition of such particles affects the rheological responsiveness of the hydrogels (which is critical during the printing process) as well as mechanical parameters like the elastic modulus. This study tries to answer this question using a specific system: an alginate-gelatine hydrogel containing polyhydroxybutyrate-co-hydroxyvalerate (PHBV) microparticles. Scaffolds were made by bioprinting and moulding incorporating PHBV microspheres (7–12 μm in diameter) into alginate–gelatine inks (4.5 to 9.0% w/v). The microparticles (MP) were predominantly located within the polymeric matrix at concentrations up to 10 mg MP/mL ink. Higher particle concentrations disrupted their spatial distribution. Inks pre-crosslinked with 15 mM calcium and containingMPat concentrations ranging from 0 to 10 mg/mL demonstrated rheological characteristics appropriate for bioprinting, such as solid-like behaviour (G′ = 1060–1300 Pa, G″ = 720–930 Pa), yield stresses of 320–400 Pa, and pseudoplastic behaviour (static viscosities of 4000–5600 Pa·s and ~100 Pa·s at bioprinting shear rates). Furthermore, these inks allow high printing quality, assessed through scaffold dimensions, filament widths, and printability (Pr > 0.94). The modulus of elasticity in compression (E) of the scaffolds varied according to the content of MP and the manufacturing technique, with values resembling those of soft tissues (200–600 kPa) and exhibiting a maximum reinforcement effect with 3 mg MP/mL ink (bioprinted E = 273 ± 28 kPa; moulded E = 541 ± 66 kPa). Over the course of six days, the sample’s mass and shape remained stable during degradation in simulated body fluid (SBF). Thus, the alginate–gelatine hydrogel loaded with PHBV microspheres inks shows promise for targeted drug delivery in soft tissue bioengineering applications.