Associate professor of biology Andy Smith presented "Adhesive Gels from Snails and Slugs: Strong, Highly Flexible Glues That Depend on Iron" at the Adhesion Society Conference in Tampa, Florida.
Abstract
"Gastropod molluscs such as snails and slugs can create strong, temporary adhesion using dilute gels. These gels consist of over 95 percent water, yet can adhere to a wide variety of surfaces with tenacities that typically range from 100 to 500 kPa. Because of the novel characteristics of these glues, there is good potential for biomimetic applications. Thus, a major goal is to identify the mechanism that makes these dilute gels adhesive. The key structural feature of these glues is the presence of gel-stiffening proteins that have been called 'glue proteins.' Recent work has identified several important biochemical features of these proteins, the most striking of which is their association with iron. Removing or binding this iron with a highly specific iron chelator blocks the ability of the glue proteins to function in a variety of different assays. These observations suggest several possible mechanisms by which the glue proteins may act."
Session of interest: Biological and Biomimetic Adhesion Surfaces
Andy also presented "Gluing With an Iron Fist: Crosslinking in Molluscan Adhesive Gels" at the Society for Integrative and Comparative Biology Meeting in Phoenix, Arizona.
Abstract
"Many gastropod molluscs produce strong adhesion with soft, dilute gels. A major question is how such gels can become powerful adhesives. Previous research has identified specific glue proteins that appear to crosslink the gels and may be involved in interfacial adhesion, but the mechanism has not yet been identified. We studied the rapidly-setting defensive glue secreted by the slug Arion subfuscus. The proteins that constitute this gel are sensitive to the presence of iron. Atomic absorption spectroscopy on the dissolved glue and iron-specific stains on blots of the proteins show that the primary glue protein has iron bound at approximately a 1:1 molar ratio. This is the only protein in the glue that binds to iron strongly. Removal or binding of this iron with a high-affinity, iron-specific chelator shows that iron plays a major role in the function of the gel. Chelation of iron may inhibit the setting of the glue, as demonstrated by a marked increase in solubility when the chelator is added before the glue sets. Chelation also completely blocks the ability of the glue proteins to function in a gel-stiffening assay. This evidence suggests that iron associated with the glue proteins participates in crosslinking reactions that are essential for the mechanics and integrity of the gel. A mechanism involving iron could explain the ability to form strong, non-specific adhesion with dilute glues in an aqueous environment."
