Researchers at Northwestern University designed a polymer based on the proteinaceous glue mussels use to attach themselves to substrates. This novel adhesive forms a thin film under some circumstances and can coat surfaces with most any functional material.

One application proposed by this team incorporates pellets coated with the adhesive for water purification. As water runs through a cylinder containing the pellets, the adhesive pulls toxic metals out of the water by binding to them.

Read more about it here:
http://www.technologyreview.com/Nanotech/19619/