Progress in Medical Nanomachinery
Researchers are already moving beyond complex nanoparticles and into the realm of the first simple medical nanomachines. Via EurekAlert!: "Known as a 'nanoimpeller,' the device is the first light-powered nanomachine that operates inside a living cell, a development that has strong implications for cancer treatment. ... Nanomaterials suitable for this type of operation must consist of both an appropriate container and a photo-activated moving component. ... researchers used mesoporous silica nanoparticles and coated the interiors of the pores with azobenzene, a chemical that can oscillate between two different conformations upon light exposure. Operation of the nanoimpeller was demonstrated using a variety of human cancer cells, including colon and pancreatic cancer cells. The nanoparticles were given to human cancer cells in vitro and taken up in the dark. When light was directed at the particles, the nanoimpeller mechanism took effect and released the contents. The pores of the particles can be loaded with cargo molecules, such as dyes or anticancer drugs. In response to light exposure, a wagging motion occurs, causing the cargo molecules to escape from the pores and attack the cell. ... impeller operation can be regulated precisely by the intensity of the light, the excitation time and the specific wavelength."
Link: http://www.eurekalert.org/pub_releases/2008-03/uoc--urd033108.php