• Modeled the amorphous region of silkworm silk and folded structure with replica-exchange MD simulations; 

• Calculated the ionic conductivity and diffusion coefficient in the system with different water contents in MD simulation; 

• Explored the positional relationships of silk, Ca2+, and water molecules in the system; 

• Investigated binding properties of the Gly-Ala dipeptide/Gly-Ser dipeptide, Ca2+, and water molecules using DFT calculations.

Outcomes and impact: 

• Matched the results of ionic conductivity in Silk-Ca ICs at different water content calculated in experiments; 

• Observed the Ca2+ binding sites in silk were oxygens in peptide bond or Ser side-chain hydroxyl, and such interactions were weakened with the increase of water content; 

• Showed the formation of water shell around the Ca2+ at a distance between 2.1 to 2.6 Å, which can hydrogen bonded with silk protein; 

• Concluded the ionic conduction mechanisms in protein-ion systems, which can guide the design of ionic conductors with good stretchability and self-healing properties.

Yu, X.*, Hu, Y.*, Shi, H.*, Sun, Z., Li, J., Liu, H., ... Yeo, J.†, Lu, Q.†, & Guo, C.† (2022). Molecular Design and Preparation of Protein-Based Soft Ionic Conductors with Tunable Properties. ACS Applied Materials & Interfaces, 14(42), 48061-48071. https://doi.org/10.1021/acsami.2c09576