Injectable Tunable Magnetic Gellan Gum-Based Hydrogel for Regenerative Medicine

Controlled cellular alignment plays a crucial role in the microarchitecture of many human tissues dictating their biological and mechanical function.1 Nowadays a multitude of techniques have been described to control cellular alignment, but the resulting 3D aligned scaffolds usually need invasive surgery to be implanted. Among the biomaterials, injectable hydrogels could be transplanted via minimally invasive injection, but without displaying any aligned structure. In the present work, we develop a novel tunable and injectable system starting from gellan gum (GG), a biocompatible bacteriaderived polysaccharide,2 that can achieve an oriented architecture upon a magnetic field application thanks to the presence of magnetized collagen fibrils embedded into the GG matrix. GG-based hydrogels were fabricated using bivalent ions and cell culture media by dropping the system through a 30G needle. The resulting system was also implemented with hyaluronic acid (HA) and carboxymethyl-chitosan (CMC). The samples were characterized using rheology, the stability and the swelling ability of hydrogels were investigated up to 21 days. Sodium citrate was added to iron oxide nanoparticles to improve their stability, then mixed with collagen type I to obtain magnetic fibrils. This system was added to the hydrogel system to obtain an oriented architecture. The hydrogels showed a dependence of stability, mechanical properties, and swelling degree on their composition. The hydrogel biocompatibility was preliminarily screened on fibroblasts by analyzing cell viability and cell morphology up to 7 days.