Hydration-dependent mechanics and structural resilience of jelly fungi as natural blueprints for bioinspired hydrogels.

Abstract

Jelly fungi function as natural hydrogels capable of tolerating extreme hydration changes and large deformation, making them valuable models for resilient soft materials. This study examines the mechanical behavior of Exidia glandulosa and Phaeotremella frondosa across hydrated and dehydrated states using compression testing, nanoindentation, microscopy, and finite element modeling. The two species display distinct structure-property relationships governed by hyphal architecture. E. glandulosa contains thick, bundled hyphae and crystalline inclusions that support higher hydrated stiffness and strong recovery during cyclic loading. P. frondosa, with finer hyphae, behaves similarly to polymeric hydrogels but becomes exceptionally stiff when dried. These findings show that a reinforced hyphal network combined with a gel-rich matrix enables stability under repeated loading and offers design principles for synthetic hydrogels with improved mechanical resilience. STATEMENT OF SIGNIFICANCE: Hydrogels are inherently soft materials, and their mechanical performance is often limited by homogeneous network structures that deform uniformly underload. This study demonstrates that jelly fungi represent a natural class of soft hydrogels whose stiffness and resilience are enhanced not by chemical modification, but by the presence of embedded hyphal architecture within the gel matrix. These internal reinforcements enable jelly fungi to exhibit stiffness comparable to, and in some cases exceeding, that of polymeric hydrogels, while also providing improved resistance to large cyclic deformations. By revealing how structural design alone can tune mechanical behavior, this work highlights bioinspired strategies for engineering hydrogels with targeted stiffness, durability, and damage tolerance through architectural control rather than changes in material chemistry.