Most sensors used to measure pollutants in lakes and rivers fail to detect small concentrations that may still be harmful to humans. Researchers at the University of Tokyo’s Institute for Industrial Science have designed an ultrasensitive device that uses human cells to detect these low but hazardous levels.
The sensor consists of a fine plastic tube containing lab-grown human cells. A sample of water is poured into the tube, along with a low-density lipoprotein (a compound made of fat and protein) tagged with a fluorescent dye. Toxic chemicals in the water slow down cells’ uptake of the lipoprotein, resulting in dimmer fluorescence. In preliminary tests, the disposable sensor detects the presence of small traces of such poisonous compounds as lead nitrate, acetaldehyde and sodium arsenite (all of which impede lipoprotein uptake) in two hours, versus the two days that conventional laboratory sensors would need to register them. Yasuyuki Sakai, one of the scientists who developed the device, says it could take up to five years to bring it to market.