Basically they structured peptides in a metal organic framework (MOF). A cage where peptide (small proteins). When a salt that chelates and degrades the MOF is introduced the peptide leaks out make a hydrophobic aggregate on the surface of the water. This reduces the surface tension of the water at that point and makes a surface tension gradient propelling the boat forward a phenomenon known as the Maragoni effect (tears in wine). Cool right? We have seen similar boats like this before (like that kid in the science fair and Robin Ras at Aalto) where they use some hydrophobic substance to propel the boat. The peptide aggregation is something interesting mainly because you might be able to use different peptides or perhaps other biochemicals like nucleotides to get a more hydrophobic effect.