It’s hard to imagine building things as small as a cell, but now we can make things even smaller than that—as small as viruses or even DNA. This month, we talk to Dr. Tejal Desai from the University of California at San Francisco about nanotechnology’s fortuitous interface with the tiny stuff of biology. Research in this area has dramatic implications for the future of medicine. It could lead to artificially engineered tissues, for example, and more effective drug delivery. It could also result in new kinds of health monitoring devices, as Dr. Thomas Murray, from the Hastings Center, explains.