Adhesion with tough gels inspiration from the sticky defensive secretions of dusky slugs

January 3 – Febuary 28, 2021

Meeting Abstract

S8-8  Wed Jan 6 16:00 – 16:30  Adhesion with tough gels: inspiration from the sticky defensive secretions of dusky slugs Smith, AM; Ithaca College

Tough gels have great potential as medical adhesives. Their deformability makes them much more compatible with soft tissues than solid adhesives. While many gels are better suited as lubricants, recent work has characterized gel-toughening mechanisms that can lead to markedly different mechanics. The dusky slug Arion subfuscus takes advantage of such a mechanism to produce an extraordinary defensive secretion. It exudes from the animal’s back and adheres strongly to whatever touches it, rapidly setting into a tough glue. The glue has several highly desirable properties: 1) it adheres to a wide variety of surfaces despite the presence of water, 2) it sets rapidly, changing from a viscous exudate into a firm gel within seconds, and 3) it is unusually tough. Recent work has clarified how it gains these properties. A group of highly abundant proteins that are unique to the glue adhere to different surfaces. These proteins are ligand-binding proteins related to lectins, and likely oligomerize to present multiple binding domains that can join the glue components to the surface. These glue components set rapidly via an oxidation reaction leading to stable cross-links within a protein network. Finally, the combination of a polysaccharide and a protein network creates a double network that acts synergistically to provide toughness. The polysaccharides are folded and easily extensible, but the interpenetrating proteins are extensively cross-linked to provide stiffness. The cross-links act as sacrificial bonds, dissipating energy as they fail. This requires a great deal of energy because the polysaccharides ensure that the glue deforms extensively before failure. The structural features that provide adhesiveness, rapid setting, and toughness provide an intriguing blueprint from which to design novel medical adhesives.

the Society for
Integrative &