The Year in Materials

Stretchable electronics and the strongest material ever were just two achievements of 2008.

Graphene, the material behind one of our 10 emerging technologies of 2008, stayed in the news all year. In July, researchers who poked the single-atom-thick carbon sheets with the tip of an atomic force microscope confirmed that graphene is thestrongest material ever tested. But most of the graphene community, includingKostya Novoselov, one of the first to make graphene and one of TR's top 35 innovators under 35 in 2008, is interested in graphene's electrical properties. Last month, two separate groups of researchers reported that they had made fast graphene transistors that could be used for wireless communications. Other researchers addressed the problem of manufacturing graphene. Novoselov and his collaborators originally made the single-atom-thick hydrocarbon sheets by crushing graphite between two layers of tape. But more scalable graphene-manufacturing technologies will be needed for the material to be adopted by the chip industry. One group at the University of California, Los Angeles, developed a simple method for making large sheets of graphene by dissolving graphite in hydrazine.

World’s strongest material: Researchers who probed single-atom-thick graphene with a sharp diamond tip found that it’s the strongest material ever tested. The illustration shows the atomic structure of graphene, a mesh of carbon and hydrogen atoms.
Credit: Jeffrey Kysar, Columbia University

Nanomedicine and Nanomaterials Safety
Researchers made a number of advances in understanding how to make nanomaterials that take a drug straight to diseased cells in the body, which should improve the efficacy and safety of therapies for cancer and many other diseases. They found thatnanoparticles shaped like bacteria did a better job getting inside cells, and developed ways to get drugs to the right subcellular machine. And they made major progress in developing agents to deliver RNA. Delivery has been one of the biggest obstacles to a promising therapeutic technique called RNA interference, which uses strands of RNA to muffle the activity of disease genes. A method for screening large numbers of fatty-molecule carriers allowed the company Alnylam Pharmaceuticals to make carriers for delivering RNA to respiratory cells and other targets in mice.

However, there was some bad news this year about the safety of nanomaterials. Two studies in mice suggested that carbon nanotubes could behave like asbestos in the lungs, causing cancer. Whether the nanotubes can, like asbestos, be easily inhaled is just one of many remaining questions. Nanomaterials are diverse in their chemistry and structure, and it's difficult to make generalizations about their safety. One study this year attempted to address this diversity. Researchers developed a method forscreening a diverse group of nanomaterials in large numbers and in many kinds of human cells.

Stretchable, Flexible, Wearable Electronics
Other researchers integrated carbon nanotubes into a number of devices. Researchers in Japan made a stretchy electronic circuit by adding carbon nanotubes to a polymer, creating a material that could be used to make stretchable displays and simple computers that wrap around furniture. In China, researchers made thin, transparent,flexible speakers from carbon nanotubes. And researchers in Illinois made stretchable silicon electrical circuits whose performance equals that of their rigid counterparts.

By coating cotton thread with a mixture of carbon nanotubes and a conductive polymer, researchers in Michigan made fabrics that can perform sophisticated computation and act as wearable biosensors whose sensitivity to biological molecules rivals that of conventional diagnostics.