Mechanical Properties of Chitin-Protein Interfaces: A Molecular Dynamics Study

The mechanical behaviors of chitin, proteins, and their interfaces are important factors in defining the overall mechanical properties of "chitin-based" biological materials, including lobster shells, squid beaks, and spider's fangs. Additional effects arise from their solvent environments such as water and inorganic ions. In this paper, we explored the molecular-level mechanics of the chitin-protein interface by performing molecular dynamics simulations. Model proteins including α-helices and β-sheets were investigated, showing secondary structure-dependent chitin-binding behaviors through hydrogen bonds (H-bonds). The results indicate that the terminals of proteins anchor them on the chitin substrate through H-bonds and contribute to the interfacial strength. Furthermore, it is shown that the presence of water at the interface reduces its strength by weakening the H-bonds network (by approximately two thirds for the α-helix in our model). The results and conclusion from this simple model for the chitin-protein interface are expected to shed some light on the complete exploration of multiscale mechanics in biological materials with such type of interfaces. © 2013 Springer Science+Business Media New York.