Architectural Self-Assembled Fungal Mycelium for Nanofluidic Ion Regulation

Conventional nanofluidic platforms rarely achieve the simultaneous combination of ion regulation, structural tunability, and scalable fabrication. Here, we demonstrate using fungal mycelium as a self-grown morphology-adaptable nanofluidic medium. Leveraging the natural growth of blue oyster mycelium, we directly fabricate 1D twisted fibers, 2D membranes, and 3D foams─without chemical modification─through simple lyophilization and mechanical shaping. These architectures preserve interconnected hyphal nanochannels with a naturally negative surface charge (-1.85 to -2.77 mC m^-2, tunable via growth time), enabling stable ionic conductivities of 0.2-0.5 mS cm^-1 in dilute potassium chloride (KCl) electrolyte (<1 × 10^-3 mol L^-1), several orders of magnitude above bulk values. Distinct from inorganic and polymeric analogues, the mycelium-based nanofluidic material system is shape-adaptable, flexible, biocompatible, and environmentally benign, offering a scalable pathway to green shape-adaptable ionic devices. By uniting intrinsic biological architectures with engineering control, this work establishes fungal mycelium as an emerging platform for next-generation nanofluidics.