PtP
28-11-2005, 05:17 PM
A dense bed of light-sensitive bacteria has been developed as a unique kind of photographic film. Although it takes 4 hours to take a picture and only works in red light, it also delivers extremely high resolution.
The “living camera” uses light to switch on genes in a genetically modified bacterium that then cause an image-recording chemical to darken. The bacteria are tiny, allowing the sensor to deliver a resolution of 100 megapixels per square inch.
To make their novel biosensor, Chris Voigt’s team at the University of California in San Francisco, US, chose E. Coli, the food-poisoning gut bacterium. One of the reasons for that choice is that E. Coli does not normally use light - photosynthesising bacteria could have used light to prompt other, unwanted, biological processes.
The researchers used genetic engineering techniques to shuttle genes from photosynthesising blue-green algae into the cell membrane of the E. coli. One gene codes for a protein that reacts to red light.
Once activated, that protein acts to shut down the action of a second gene. This switch-off turns an added indicator solution black.
As a result, a monochrome image could be permanently “printed” on a dense bed of the modified E. Coli.
The living camera will never be available in the shops: Voigt’s team saw it as an exercise in advanced genetic engineering. But their success in getting an array of bacteria to respond to light could lead to the development of “nano-factories” in which minuscule amounts of substances are produced at locations precisely defined by light beams.
For instance, the gene switch need not activate a pigment, says Voigt. A different introduced gene could produce polymer-like proteins, or even precipitate a metal. “This way, the bacteria could weave a complex material,” he says.
The UCSF team are now working on expanding the colour range of their sensor, perhaps using retinol, a substance which helps the human retina to sense a wide range of colours.
As a method of nano-manufacturing, the biocamera is an "extremely exciting advance" says Harry Kroto, the Nobel prize-winning discoverer of buckminsterfullerene, or buckyballs. "I have always thought that the first major nanotechnology advances would involve some sort of chemical modification of biology."
The “living camera” uses light to switch on genes in a genetically modified bacterium that then cause an image-recording chemical to darken. The bacteria are tiny, allowing the sensor to deliver a resolution of 100 megapixels per square inch.
To make their novel biosensor, Chris Voigt’s team at the University of California in San Francisco, US, chose E. Coli, the food-poisoning gut bacterium. One of the reasons for that choice is that E. Coli does not normally use light - photosynthesising bacteria could have used light to prompt other, unwanted, biological processes.
The researchers used genetic engineering techniques to shuttle genes from photosynthesising blue-green algae into the cell membrane of the E. coli. One gene codes for a protein that reacts to red light.
Once activated, that protein acts to shut down the action of a second gene. This switch-off turns an added indicator solution black.
As a result, a monochrome image could be permanently “printed” on a dense bed of the modified E. Coli.
The living camera will never be available in the shops: Voigt’s team saw it as an exercise in advanced genetic engineering. But their success in getting an array of bacteria to respond to light could lead to the development of “nano-factories” in which minuscule amounts of substances are produced at locations precisely defined by light beams.
For instance, the gene switch need not activate a pigment, says Voigt. A different introduced gene could produce polymer-like proteins, or even precipitate a metal. “This way, the bacteria could weave a complex material,” he says.
The UCSF team are now working on expanding the colour range of their sensor, perhaps using retinol, a substance which helps the human retina to sense a wide range of colours.
As a method of nano-manufacturing, the biocamera is an "extremely exciting advance" says Harry Kroto, the Nobel prize-winning discoverer of buckminsterfullerene, or buckyballs. "I have always thought that the first major nanotechnology advances would involve some sort of chemical modification of biology."