The Nano-Scale Secret of Biological Secretion for Adhesion

Abstract

We discovered, by employing the atomic force microscope and transition electron microscopy, that 1) ivy and marine mussels secrete nanoparticles for surface permanent adhesion, whose force is significant larger than the force generated by gecko for reversible surface adhesion; and 2) Sundew secretes nanoparticles, which are cross-linked with muco-polysaccharide for high elastic adhesive for prey trapping. The nanoparticle-based adhesion mechanism has important implications for engineering surface adhesive materials and devices for biomedical applications.Adhesion in nature has been the focus of intense study over the past few years. Nevertheless, research in this field has primarily concentrated on understanding the chemical aspects of adhesion. While scientists have been able to determine some of the molecular structures present in the adhesives secreted by surface affixing biological systems, such as mussels and barnacles, the fundamental adhesion mechanisms used by these systems are still unknown. This research focuses on the nano-scale morphological similarities of adhesive materials secreted from marine mussels, barnacles and ivy. We have discovered that marine mussels secrete large amounts of adhesive materials in the form of nanoparticles for surface adhesion. This is in keeping with our previous work, which indicated a similar phenomenon for ivy. Both studies concur with earlier research on marine barnacles, polychaetes and sea stars. Taken together, these results indicate that nanoparticles are used by natural, biological systems to increase surface adhesion.We recently extended the study to Sundew and observed that nanoparticles secreted from the Sundew tentacles form scaffolds by cross-linking with muno-polysaccharide. The secreted material is highly elastic and has been effectively used by the sundew for trapping prey.The ivy nanoparticles have been isolated from the secretion using SEC-HPLC. Physical properties have been further characterized and will be discussed in details through this talk.