Ultrashort Peptides as Versatile Materials for Biomedical Applications—From Scaffolds for 3D Cell Culture to Strong Adhesives.

Ultrashort amphiphilic peptides with a characteristic sequence motif and containing up to seven natural amino acids exhibit self-assembling dynamic behaviours under physiological conditions. Despite their small size, they can form α-helical, β-sheet and β-turn secondary structures in aqueous solutions. At higher concentrations, they form nanofibers, leading to hydrogels with a very high content of water (>99%w/w). These hydrogels are biocompatible, biodegradable, and generally non-immunogenic and can find applications as 3D cell culture substrates, bioinks for 3D bioprinting, hemostatic agents, drug delivery systems, materials for soft tissue repair and others. Inspired by nature and particularly by the mussel’s foot proteins that consist of a high content of a modified amino acid, 3,4-dihydroxy-L-phenylalanine (L-DOPA) and by introducing L-DOPA to the ultrashort peptide sequence, we successfully developed hydrogels with adhesive properties for wet environments, while keeping the characteristics of self-assembly. Moving a step forward by introducing a polymerizable group to the peptide sequence, we were able to crosslink the peptide-derived supramolecular structures to covalent polymeric networks. Toward this direction, we synthesized a peptide with catechol moieties and more than one vinyl group to act as a crosslinker. An aqueous mixture of our polymerizable peptide, the crosslinker and a water-soluble photoinitiator can be polymerized instantly under a LED light source to give a strong adhesive. This peptide-based glue cannot only glue objects that weigh more than two kilos but, most importantly can be applied under water. This type of adhesive peptide materials can be used for wound healing, as surgical adhesive glues, and in today’s ecological challenges like coral reef restoration.