Massachusetts Institute of Technology
This eclectic investigator draws inspiration from nature's genius for building things at the nanoscale
The crux of nanotechnology is the problem of self-assembly, getting uncooperative atoms to link and align themselves up in precise ways. We know it can be done, of course: life persists by turning molecules into complex biological machinery. How fitting, then, that one of today's most creative materials scientists, Angela Belcher of the Massachusetts Institute of Technology, has turned to nature for assistance. Belcher has pioneered the use of custom-evolved viruses in synthesizing nano-scale wires and arrays, fusing different research disciplines into something uniquely her own.
Belcher got her start with abalone, a cousin to oysters. The mollusk had evolved a system for accreting a hard shell from calcium carbonate, the same material of which chalk is made. As a graduate student at the University of California, Santa Barbara, Belcher elucidated the molecular assembly scheme abalone employed to grow its shell and tweaked a key protein to accelerate the growth process. Soon head of her own lab, she was standing on her desk one day, pondering the periodic table of elements and wondering how far she could push nature's ability to manipulate inorganic elements.
Abalone had learned to control calcium. She decided that she would teach nature to work with the rest of the list. "The aim is to work our way through the whole periodic table and be able to design materials of all kinds in a controlled way. My biggest goal is to have a DNA sequence that can code for the synthesis of any useful material," she told MIT's Technology Review.
She started with the DNA sequence of the M13 bacteriophage, a long, tubular virus six nanometers wide. She engineered a version of the virus that latched onto quantum dots, nanometer-size specks of semiconductor with desirable electromagnetic properties, by repeatedly selecting the virus particles best able to cling to the dots. In a matter of months she evolved a virus that held a chunk of material steadfastly on one end, like a ball and chain. By dissolving the virus particles she could make them align themselves thickly like hairs all capped with quantum dots. The viruses are packed so densely that they essentially form thin films, which can be stacked closer together than other means can quickly achieve.
More recently she customized M13 to stud its length with metal particles such as cobalt oxide and gold, yielding metal nanowires that could be used in high energy-density electrodes. By growing the virus on a film she could make a thin, flexible metal oxide coating suitable for storing energy chemically. Those could be incorporated, for example, into thin-film batteries that coat the surface of a device or fit into nonstandard shapes. Belcher co-founded Cambrios Technologies in Mountain View, Calif., to turn some of her demonstrations into commercial devices such as solar cells and light-emitting diodes. She has her sights on other organisms too and has started working with yeast in order to engineer more complex nanostructures.
To meet her goals, Belcher has committed herself to adding a new field to her repertoire every five years. Starting as a biochemist, she has incorporated materials chemistry, electrical engineering and molecular biology, in effect starting from scratch each time. Like the abalone's shell, this bit-by-bit accretion yields solid results.