Scientists marvel at the ability of geckos to walk up walls and even across ceilings, thanks to their sticky feet. Like Post-it notes, gecko feet can be lifted from surfaces again and again without losing their stickiness.

Scientists also admire the mussel, able to adhere firmly to underwater surfaces. Now two Northwestern University biomedical engineers have created the best of both worlds: "geckel," a strong but reversible adhesive that works in air or water.

Phillip B. Messersmith and Haeshin Lee created geckel by nanofabricating arrays of silicone pillars that resemble the super-fine hairs on the bottom of a gecko foot. Then they coated the pillars with a thin layer of synthetic polymer modeled after the "glue" proteins found in mussels.

One possible application is a geckel bandage that would remain firmly attached during bathing but could be easily removed after a wound has healed. It might replace stitches in some cases.—Dawn Stover

Image by H. Lee, W. Lim and A.J. Kane.