Issue link: http://read.uberflip.com/i/5219
12 winter 2009 Ned Seeman's Home Page http://seemanlab4.chem.nyu.edu/ resources MICHAEl ANISSIMOv nAnOSCALE: ARTwORk COURTESy Of nAdRIAn C. SEEMAn — TRIggERfISH: IMAgES COURTESy Of SEnSIMEd Ag nanoscale Robot Arm Places Atoms and Molecules With 100% Accuracy uNTIl THE MID-1990S, THE TERM "NANOTECHNOlOGY" REFERRED TO THE GOAl OF CREATING vAST ARRAYS OF NANOSCAlE ASSEMBlERS TO FABRICATE uSEFul HuMAN-SCAlE PRODuCTS FROM SCRATCH IN AN ENTIRElY AuTOMATED PROCESS AND WITH ATOMIC PRECISION. Since then, the word has come to mean anything from stain-resistant pants to branches of conventional chemistry — generally anything involving nanoscale objects. But the dream of a new Industrial Revolution based on nanoscale manufacturing has not died, as demonstrated most vividly by the work of NYu professor of chemistry Dr. Nadrian Seeman. In a 2009 article in Nature Nanotechnology, Dr. Seeman shared the results of experiments performed by his lab, along with collaborators at Nanjing university in China, in which scientists built a two-armed nanorobotic device with the ability to place specific atoms and molecules where scientists want them. The device was approximately 150 x 50 x 8 nanometers in size — over a million could fit in a single red blood cell. using robust error-correction mechanisms, the device can place DNA molecules with 100% accuracy. Earlier trials had yielded only 60-80% accuracy. The nanorobotic arm is built out of DNA origami: large strands of DNA gently encouraged to fold in precise ways by interaction with a few hundred short DNA strands. The products, around 100 nanometers in diameter, are eight times larger and three times more complex than what could be built with a simple crystalline DNA array, vastly expanding the space of possible structures. Other nanoscale structures or machines built by Dr. Seeman and his collaborators including a nanoscale walking biped, truncated DNA octahedrons, and sequence-dependent molecular switch arrays. Dr. Seeman has exploited structural features of DNA thought to be used in genetic recombination to operate his nanoscale devices, tapping into the very processes underlying all life. The advances in DNA nanotechnology keep coming, and many observers are wondering if this will be the path that leads us to the next Industrial Revolution. Only time — and many more experiments — will tell. Schematics (a) and Atomic Force Micrographs (b) of the Origami Arrays and Capture Molecules. Panel i of (a) illustrates the origami array containing slots for the cassettes and a notch to enable recognition of orientation; the slots and notches are visible in the AFM in (b). Panels ii show the cassettes in place; the color coding in (a) used throughout the schematics is green for the PX state and violet for the JX2 state; the presence of the cassettes is evident in the AFM image in (b). Panels iii illustrate the PX-PX state which captures a triangle pointing towards the notch in the schematic (a) and in the AFM image (b). Panels iv illustrate the PX-JX2 state (a), containing a triangle that points away from the notch, which is evident in the AFM image (b). Panels v illustrate the JX2- PX state which captures a diamond-shaped molecule (a); its shape is visible in the AFM image (b). Panels vi show the linear molecule captured by the JX2-JX2 state, both schematically (a) and in the AFM image (b). a B