A cunning molecule shaped like a meatball and studded with molecular bait , could be the answer to combating biological weapons. Deadly viruses are popular candidates for biological warfare, as they can penetrate gas masks and protective clothing. To infect cells, viruses must first attach to their surfaces by binding to specific receptors on the cell surface. However if you create decoys laden with these receptors, you can mop up viruses and some bacteria before they reach the cells. These decoys are called Dendrimers, which are molecules that branch again and again forming spherical blobs, and they have already been shown to prevent flu viruses from infecting blood cells in culture. Such nanodecoys could stop viral invaders which have filtered into gas masks or been injected directly into people.