Comparative Investigations of the Sandfishs β-Keratin (Reptilia: Scincidae: Scincus scincus). Part 2: Glycan-Based Friction Reduction

The sandfish (Scincidae: Scincus scincus) is a lizard having outstanding skin properties. The scales show low friction behaviour and high abrasion resistance. After giving molecular support by DNA and protein analysis in Part 1 for increased glycosylation of the skins β-keratins, in this study the effect of glycans for friction reduction was investigated by (1) ammonium-based keratinolysis of skin exuviae and applying a β-keratin film on a glass surface and by (2) β-elimination based deglycosylation of β-keratins and immobilization of liberated glycans on a glass surface via silanisation. Both techniques resemble the natural model in the species investigated, the sandfish Scincus scincus and the Berber skink Eumeces schneideri. In the sandfish, a decreased friction coefficient was found by friction angle measurements, and a low adhesion force was measured by investigation with atomic force microscopy (AFM). These characteristics are possibly based by prevention of the formation of van der Waals bonds. This low adhesion force correlates with low friction and has a positive impact on abrasion resistance. A monosaccharide analysis confirmed the presence of carbohydrates.