Scientists from Northwestern University in Illinois and the Kensey Nash corporation have developed a new synthetic adhesive that combines the dry adhesion of gecko feet with the wet adhesion of mussel byssus threads. The material, called Geckel, has proven to be a strong and reversible adhesive on both dry and wet surfaces, a feat not demonstrated by either geckos or mussels. Gecko feet generate adhesion by taking advantage of a phenomenon called ‘contact splitting.’ The enormous surface area of the split-ended hairs on the lizards’ feet creates a disproportionately large region of attraction (based on van der Waals forces) compared to the apparent surface area of the feet. The researchers mimicked this nanostructure by synthesizing arrays of silicone pillars on a solid substrate. However, like gecko feet, this synthetic surface failed to produce adhesion when wet. Mussels produce adhesive protein polymers containing an amino acid called DOPA, which is thought to play a key role in adhesion. When synthetic DOPA polymer was applied to the surface of the silicone pillars, it was able to generate adhesion even when wet. The biomimetic hybrid material maintains adhesion for over 1000 contact/release cycles, even when wet. The researchers hope that this revolutionary new material will be useful for the production of new bandages and transdermal drug-delivery patches. These products would be impervious to water and extremely sticky yet capable of being removed when they are no longer needed.
Geckel nano-adhesive could be more effective than traditional adhesives and used for more diverse applications.
Most adhesives lose effectiveness when wet. In addition, there are few adhesives that maintain activity over the course of repeated contact cycles. Geckel nano-adhesive could be superior to conventional adhesives for certain applications.