Ionic Dependence of Gelatin Hydrogel Architecture Explored Using Small and Very Small Angle Neutron Scattering...

The hierarchical structure of gelatin hydrogels mimics a natural extracellular matrix and provides an optimized microenvironment for the growth of 3D structured tissue analogs. In the presence of metal ions, gelatin hydrogels exhibit various mechanical properties that are correlated with the molecular interactions and the hierarchical structure. The structure and structural response of gelatin hydrogels to variation of gelatin concentration, pH, or addition of metal ions are explored by small and very small angle neutron scattering over broad length scales. The measurements of the hydrogels reveal the existence of a two-level structure of colloid-like large clusters and a 3D cage-like gel network. In the presence of Fe³⁺ ions the hydrogels show a highly dense and stiff network, while Ca²⁺ ions have an opposite effect. The results provide important structural insight for improvement of the design of gelatin based hydrogels and are therefore suitable for various applications.