Enhanced Ion Transport Through Organized Cadmium Carbonate Nanocrystals in Collagen Fibrils for Efficient Biological Memristors

Owing to the unique assembly of collagen molecules, collagen fibrils have a confined structure that can effectively guide the intrafibrillar-oriented growth of inorganic crystals, such as hydroxyapatite and calcium carbonate. However, utilizing this organized structure of mineralized collagen fibrils for rapid ion transport remains challenging. Herein, the oriented growth of functional cadmium carbonate (CdCO₃) nanocrystals is reported within collagen fibrils and demonstrates that different areas within a single mineralized collagen fibril exhibit a uniform orientation. The results show that the precursor phase infiltrates the collagen through the gap zones owing to collagen confinement, gradually transforming into well-oriented crystalline nanocrystals within the collagen. Adopting the principles of intrafibrillar mineralization with CdCO₃, the mineralization process of collagen matrices can be regulated, such as collagen films and tendon slices, by adjusting the mineralization temperature, thereby modulating the stress generated in the collagen matrices, thus highlighting new possibilities for using organized biominerals in rapid ion transport. Additionally, the use of mineralized collagen fibrils are demonstrated in biological memristors. The fabricated memristor device exhibits a low set voltage (0.65 V) and high on/off ratio (≈10⁶), highlighting the potential of mineralized collagen in advanced electronic applications.