Richard Needleman, PhD, professor of biochemistry and molecular biology, and Gang-Yu Liu, PhD, assistant professor of chemistry, have undertaken an ambitious endeavor: finding ways of making sensors by combining his bacteriorhodopsin mutants with her newly developed nanofabrication protocols to produce ultrasmall sensors. This work has implications for nanoelectronics development, the medical community and anyone who needs smaller and more sensitive sensors.
"Bacteriorhodopsin has a purple pigment normally, but you can change the color by flashing a high-intensity light on it. It changes color with light: purple to yellow, then back to purple," Dr. Needleman said. Because this bacterial protein has two controllable states, it has the potential to serve as a switch, similar to an on-off light switch or the 0-1 logic gates in computers. The light energy of the bacteriorhodopsin can be converted to electrical energy, which is the key to its utility. "In theory, anytime you can attach a protein molecule, not necessarily bacteriorhodopsin, and can get some electrical signal out of it, the applications are enormous."
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Dr. Needleman's sensor technology may be useful in many scientific and medical fields. |
Naturally occurring bacteriorhodopsin shifts from purple to yellow and back almost instantaneously, but Dr. Needleman is genetically engineering mutants that will maintain the color changes for longer periods of time, depending on the proposed use. The mutants that retain the color indefinitely would be important for computer memories while those that change back and forth would be effective as optical switches and other devices. In collaboration with Metro Laser (in Irvine, Calif.), Dr. Needleman has developed a bacteriorhodopsin-based device capable of storing more than 10,000 gigabytes on a thin 3.5-inch disk.
"We’d like to use bacteriorhodopsin’s electrical properties to manufacture very, very small devices," he explained. "Dr. Liu specializes in looking at surfaces and working on a nanoscale. We can make films of bacteriorhodopsin, and we’d like to combine the work by being able to attach the films to the surface areas of her substrates to make electrical devices or sensors."
At this point in the research, the manufacturing methods are paramount. "How you attach molecules to something on a nanoscale is very important for applications with all sorts of sensors. This is a model for doing that. It’s a way of manufacturing electrical devices, like a computer chip, on a very small scale," said Dr. Needleman.