A Malleable Collagen-Mimic that Undergoes Moisture-Induced Hardening for Gluing Hydrophilic Surfaces

A collagen-inspired helical protein-mimic has been synthesized via topochemical polymerization of a designed tripeptide monomer. In the monomer crystal, molecules arrange in a head-to-tail manner, forming supramolecular helices. The azide and alkyne of adjacent molecules in the supramolecular helix are proximally preorganized in a ready-to-react arrangement. On heating, the monomer crystals undergo regiospecific single-crystal-to-single-crystal azide-alkyne cycloaddition polymerization, yielding triazolyl- polypeptide. Polymerization softens the crystals, making the polymer malleable and mouldable. The polymer grains absorb moisture and form agglomerates through water-bridged adhesion, which hardens over time. The weight-bearing capacity of a mould made from this polymer increased by 50-fold due to moisture-induced hardening. We have demonstrated that this collagen-mimic can glue both biological specimens such as wood and bone and synthetic materials such as glass and paper. In vitro studies established the biocompatibility, making it an attractive bioinspired material for potential application as a bioadhesive.