When Art Ashkin, Steve Chu, and their colleagues at Bell Labs in Holmdel, NJ, first invented optical tweezers, they spent their days pushing around tiny, glass spheres. But it wasn't long after their 1986 discovery that they began to think about biology.
"We were trapping submicron particles of Tobacco mosaic virus," Ashkin says. "We left the samples under the microscope for a day or so, and then we discovered strange particles that seemed to be self-propelled." When they looked into the trap with a higher-quality microscope, they confirmed what the mysterious objects were. "They discovered bacteria, 350 years too late," jokes Howard Berg, who was then studying bacterial flagella at the Rowland Institute in Cambridge, Mass.
The tweezers' intense green light quickly killed the bacteria, a process Ashkin dubbed "opticution." But once the team switched to an infrared laser, the bacteria could be kept alive indefinitely, even reproducing in the ...
