Effect of bioactive borate glass on printability and physical properties of hydrogels

Abstract

Hydrogels are a key component in bioinks and biomaterial inks for bioprinting due to their biocompatibility and printability at room temperature. The research described in the present paper contributes to the advancement of bioprinting by studying the effect of bioactive borate glass (BBG) incorporated into hydrogels on printability and physical properties. In this study, we fabricated 3D-printed hydrogel scaffolds using gelatin and alginate hydrogel mixture incorporated with various amounts of BBG, a bioceramic rich in therapeutic ions including boron, calcium, copper, and zinc. We investigated the effect of incorporating BBG on the density, viscosity, physical interactions, chemical structure, and shear thinning behavior of gelatin-alginate hydrogel biomaterial ink at different temperatures. After 3D printing and crosslinking of scaffolds, we measured mechanical properties and printing outcomes. The near-optimal extrusion temperature and pressure for uniform extrusion of hydrogel filaments at various BBG contents were determined. We compared the printing outcomes by quantifying the uniformity of printed filaments and shape fidelity of printed scaffolds. The rheological analysis showed that the addition of BBG increased the viscosity of the biomaterial inks and Young’s modulus of the 3D-printed scaffolds. Biomaterial inks with a dynamic viscosity within the range of 4.5 – 6.5 Pa·s showed the best printability across all samples. In conclusion, the inclusion of BBG contributes to a substantial improvement in the physical properties and printability of 3D-printed gelatin-alginate hydrogels.