Macroscopic assembly behavior of silk/lignin-based adhesive hydrogels: elementary macroscopic assembly

Macroscopic assembly has been investigated to construct appealing materials. But it seems a question remains to be answered, i.e., is macroscopic assembly always one by one? In this study, a new kind of silk-based hydrogels were developed through incorporating lignin-related compounds via the 1-ethyl-3-(3-pyl)-carbodiimide/N-hydroxysuccinimide (EDC/NHS)-mediated coupling chemistry. Thanks to the hydrogen bond, hydrophobic and π-π interactions, the hydrogels processed capability of adhesive and macroscopic assembly, which could be further tuned by introducing iron ions, as Fe^(3+) can form coordination bonds with lignin. Examination on the three-body macroscopic assembly behavior of the silk/lignin-based hydrogels was conducted as an approach towards answering the above question. Under experimental conditions tested in this study, the answer is yes. Yet it would be reckless to draw a definitive conclusion to the question. This study intended to draw attention to this matter and evoke more interests and investigations using various macroscopic assembly systems.