Ayusman Sen and coworkers at Penn State have made the first synthetic nanoscale motor that is powered by a polymerization. First, they made "two-faced" nanoparticles that are silica on one side and gold on the other. Then they attached a Grubbs catalyst to the silica. These Ru catalysts love to grab on to double bonds and string them together. So when there is any double-bonded fuel (norbornene) around, the researchers could watch the particles being propelled towards it, and spinning out polymer chains as they go. The Royal Society of Chemistry has dubbed these nanomotors "spiders" because they spin out strands of product, and they move towards their "food".