NASA announces the use of genetic engineering to customize a protein to make it more useful for nanostructure construction.
Scientists from NASA's Ames Research Center, Moffett Field, CA, have invented a biological method to make structures that could be used to produce electronics 10 to 100 times smaller than today's components.
As part of their new method, the scientists genetically engineered proteins from "extremophile" microbes to grow onto semiconductor materials.
The microbes' environments are "extreme" to us -- near-boiling, acidic hot springs -- but just right for the biological organisms to grow mesh-like structures, known as "chaperonins," presumably for their accompanying role.
"We took a gene from a single-celled organism, Sulfolobus shibatae, which lives in near-boiling acid mud, and changed the gene to add instructions that describe how to make a protein that sticks to gold or semiconductors," said Andrew McMillan, a leader of the project.
"What is novel in our work," he continued, "is that we designed this protein so that when it self-assembles into a two-dimensional lattice or template, it also is able to capture metal and semiconductor particles at specific locations on the template surface."
The genetically engineered proteins form lattice-like structures that act as templates, and particles of gold or semiconductor material (cadmium selenide/zinc sulfide) stick to them. According to McMillan, the minute pieces that adhere to the protein lattice are "quantum dots" that are about one to 10 nanometers across. Today's standard computer chips have features that are roughly 130 nanometers apart.
The proteins can be used to make highly patterned structures.
"The cage-like chaperonin provides an ideal structure that we envisioned as being a vessel or container to use to organize nanophase materials," McMillan told nanotechweb.org. "The higher-order crystalline structures that these protein-cages can be induced to form closely resemble similar patterns that the electronics industry uses, namely in the formation of precise, regular arrays of materials on substrates."
Here, we fabricated nanoscale ordered arrays of metal and semiconductor quantum dots by binding preformed nanoparticles onto crystalline protein templates made from genetically engineered hollow double-ring structures called chaperonins. Using structural information as a guide, a thermostable recombinant chaperonin subunit was modified to assemble into chaperonins with either 3 nm or 9 nm apical pores surrounded by chemically reactive thiols.
Eric Smalley in Technology Research News has interviewed other researchers in the field who provide important qualifiers on the usefulness of the research.
Proteins are particularly useful because researchers can modify their structures in precise locations without significantly altering their folding behavior, said Zhang. "This tailor-made approach will have tremendous impact on the growth of nanotechnology and nanobiotechnology," he said. "However, much effort is still needed to reduce the high cost of production and [improve the] stability of proteins in their complexes," said Zhang.
Proteins are obviously going to turn out to be important tools for creating nanostructures. Biotechnology is probably going contribute more to nanotechnology than vice versa for some years to come. A huge number of types of proteins already exist which perform an enormous variety of molecule-level transformations Also, the machinery whereby cells synthesize proteins can be used to make whatever modified and customized proteins look like they might be useful. The techniques exist to change DNA sequences. So customized genes can be used to make customized proteins.
|Share |||Randall Parker, 2003 January 06 12:04 AM Nanotech Advances|