Mussels (and geckos) exploit all sorts of crazy chemistry that scientists are still trying to understand and learn from. Geckos’ feet are the ultimate post-it notes, sticking and unsticking to surfaces without any glue. Mussels coat their “feet” in a natural protein super-glue. Some scientists are even trying to combine the two features. I’ve written about this chemistry before, and I like to keep track of what’s going on with this sticky science.

There’s been a lot of discussion about mussels, but scientists have uncovered how these creatures marry their super-strength with flexibility on the byssal threads that attach them to solid surfaces. Most human-made coatings have to sacrifice one feature to gain on the other. The proteins on the surface of the threads contain many copies of a sticky molecule, dopa (3,4-dihydroxyphenyl-L-alanine), but that’s not enough to keep the surface hard. The proteins need the power of iron and calcium ions to keep the surface from cracking. The metal ions glom onto (chelate) the many oxygen atoms in the dopa groups and make them twice as hard as surfaces that are metal-free.