Hydrogels represent one of the most ubiquitous class of supramolecular networks which have important applications ranging from food technology to biology. Survival reasons of animals (such as hagfish) lead to a particular defense mechanism against predators. A mucin-based physical super-hydrogel is formed in few milliseconds and entraps vast amount of water. An outstanding challenge is to explore the molecular origin of slime formation, the role of the environment (natural or altered conditions) and consequently its strength. Extensional rheology of mucins were performed at different conditions by varying mucin concentrations and salt type and concentration. On the other hand, the dynamic structure of the hydrogels was investigated by means of linear viscoelasticity and dynamic light scattering. Our approach provides a simple protocol for the determination of the optimal conditions for stiffness, as defined by the longest filament breaking time and its relationship with the ionic strength. These molecular characteristics of hydrogels constitute a pathway for understanding the nonlinear rheology and, in a more general sense, the spatiotemporal techniques used allow to tune the mechanical response of polyelectrolytes such as mucus systems.
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