Wet Adhesive Nanomaterials Inspired by the Barnacle Adhesive

Abstract

Barnacles produce a micron-thick layer of ordered amyloid-like nanofibers from proteins that function as a permanent wet adhesive. Recent proteomic work from our lab shows that barnacles achieve this largely through display of complex charged chemistries using small and flexible side-chains, folded in a manner similar to adhesive silks used by spiders and insects. Their well-defined, modular, nature result in novel biomaterials that serve many purposes: adhesion, durability, bacterial resistance, and even potent enzymatic activity. Fibers are shaped by a highly conserved domain alternating between short 20-residue low complexity sequences (Gly/Ser/Thr/Ala residues) and regions with charged and aromatic side chains, with more than 80 such domains in just five proteins. The adhesive properties of these unique sequences and their function in an amyloid-like structure remain unclear. To study this, we produce miniaturized synthetic peptides from consensus barnacle cement sequences and also insert sequences into a host amyloid system of bacterial fimbriae to produce abundant and engineered wet adhesive mimics. Short synthetic peptides demonstrate that certain cement sequences specifically recognize and activate cement polymerization to form bioinspired nanomaterials. Further, bacterial biofilms are demonstrated to be a viable route for the growth of recombinant cement fibrils. These materials are characterized by AFM-based nanomechanical measurements and compared to the Wild-Type barnacle adhesive. Synthetic and recombinant adhesive materials provide a route to scale up and study a scarce but potent class of multifunctional adhesive nanostructures produced by one of the most tenacious marine fouling organisms in the ocean.