Nanovectors  made of various materials can carry medicine or  therapeutic genes
directly to a cancerous or other infected cells.
Research and development images are available at Phototake,
Visuals Unlimited, Corbis and agefotostock.

Medical concept images

Conceptual Stock Photography, Conceptual Stock Imagery, Stock Conceptual Photography,
Stock Conceptual Imagery, Conceptual Stock Illustration, Stock Conceptual Illustration,
Creative Stock Photography, Offbeat Photos, Weird Images, Odd Pictures, Strange Concepts.
Whatever you want to call it.
It's what we do.  We see things a little differently.