Gelatin–alginate–hyaluronic acid inks for 3D printing: effects of bioglass addition on printability, rheology and scaffold tensile modulus

Natural hydrogels are widely used for 3D-bioprinting because of their qualities for tissue engineering. Recently, hydrogels have been combined with bioactive glasses, due to their angiogenic properties that aid tissue regeneration. In this work, we studied the printability and the rheological properties of gelatin–alginate–hyaluronic acid inks with 2–8% wt of 45S5 bioglass (BG) that followed a pseudoplastic behavior along the 3D-printing process. The reduction in the storage modulus of the inks after adding BG indicates that the microparticles might disrupt the polymeric network; furthermore, a reduction in the viscosity was determined at BG concentrations above 6%. Inks without BG or up to 2% evidenced the best printing fidelity on 10% infill scaffolds. The tensile modulus of crosslinked 40%-filled scaffolds increased from 130 kPa (without BG) to 160 kPa (6–8% BG). Moreover, a hydroxyapatite layer appeared in scaffolds containing BG 6% and 8% wt after being cultured for 2 days. Attachment and growth of fibroblasts on the scaffolds revealed their cytocompatibility, making these materials an alternative for further research on soft tissues regeneration.