Characterizing the Role of Metal Ion Interactions in the Elasticity and Strength of Slug Glue: Steps Toward a Novel Medical Adhesive

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Stitches are often cumbersome for patients and pose a risk of infection. Thus, there is a great interest in developing medical glues that could serve as an alternative, but current adhesives are limited. Analysis of the tough, sticky defensive secretion of the slug Arion subfuscus has guided the development of a novel medical glue, and further work characterizing the slug glue should lead to deeper insights into how to make a hydrogel glue. The glue of A. subfuscus consists of a double network of carbohydrates and proteins and is held together by sacrificial bonds. These sacrificial bonds are central to the high performance of the glue, but they have yet to be identified definitively. Calcium and magnesium seem to be most likely to form intermolecular cross‐links in the glue due to their high abundance, and the abundance of calcium‐binding proteins in the glue. The role of calcium and magnesium was tested by manipulating their interactions within the glue to observe how this impacts its elasticity. Metal ion interactions were controlled by soaking glue samples in different pH buffers and determining the resulting elasticity. The glue's elasticity was measured in cut glue samples in a tensometer. The association between metal ions and glue when under different pH buffers was measured by using an atomic absorption spectrometer to determine whether the metals stayed bound in the glue or diffused out at different pH values. We found that glue elasticity varied with pH, showing a steady decline as pH dropped below 5.5. Between 5.5 and 7.5 no significant change in elasticity was apparent. This change in stiffness was not due to dissociation of calcium and magnesium, however, as they diffused completely out of the glue within sixty minutes regardless of pH. Thus, there was no correlation between the change in elasticity with pH and the loss of these metal ions, and their hypothesized role as sacrificial bonds was not supported. Further investigation aims to look into the relationship between zinc ions or imine bonds and glue elasticity and strength.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.