Dendrimers are complicated molecules with tree-like branches or arms. They were first created in the laboratory in 1979 by Donald Tomalia, a chemist working for the Dow Chemical Corporation. Both the shape and chemical composition of dendrimers can be readily engineered, making them useful in medicine. Researchers can design dendrimers so that they can be injected into the body and attach themselves to particular kinds of cells.
Dendrimers also link nanotechnology to another growing field: genetics. By embedding genetic material into the dendrimer’s branches, researchers hope to accomplish “gene therapy,” where defective or deficient genes are selectively replaced inside cells. This kind of therapy was previously attempted using a genetically modified virus, which also attaches to cells and injects its DNA, but the body would recognize these “friendly” viruses as a disease and would attack them. With dendrimers, however, there is no such immune-system reaction. However, there are still concerns with dendrimers being toxic in living animals, so engineers are still working to convince doctors that they are safe enough to use on humans.