Scientists say they have developed a fast and supersensitive new test for ricin, a poison found in castor beans that scientists say is a prime candidate for use in bioterrorism attacks. The new method, described in research recently published in Analytical Chemistry, takes only three minutes to detect ricin and is 100 to 1,000 times more sensitive than tests currently available, according to study co-author Vern Schramm, a biochemist at the Albert Einstein College of Medicine of Yeshiva University in Bronx, N.Y.
Ricin comes from the castor bean plant Ricinus communis, which is easy and cheap to grow. Extracting the poison from the beans requires simple chromatography, a method of separating chemicals taught in college chemistry classes. If eaten, inhaled or injected into the bloodstream, ricin kills cells by interfering with their ability to manufacture proteins, which can lead to organ failure and death, Schramm explains. There is no treatment for ricin exposure, according to the U.S. Centers for Disease Control and Prevention (CDC).
Current methods for detecting ricin usually involve combining a sample (such as a white powder found in an envelope) with proteins that bind to the ricin toxin, and then running the mixture through a mass spectrometer that sorts chemicals according to their mass and electrical charge, Schramm says. This process takes hours, if not days, and must be conducted in a lab, he adds.
The new test, on the other hand, takes only three minutes and could be packaged in a small, portable kit, Schramm says. He describes the test like this: you place sample of suspicious material in a test tube containing ribosomal RNA, the component of the cell's protein-making factory that is attacked and disabled by ricin. If the poison is present, it will react with the ribosomal RNA, setting off a chemical cascade that activates a luminescent protein called luciferase. So if luciferase lights up, then ricin is present.
"We patented it [and] we hope some company or the Army will take up this method and use it," Schramm says. He says the test, which can detect one billionth of a gram of ricin, could potentially help minimize the number of false alarms, such as one that occurred in London in 2003 when authorities arrested a group of suspected terrorists after finding evidence of ricin in their apartment only to discover later that the test had suggested the presence of ricin when it was not really there. Schramm says that it is too early to say how often the new test yields false positives, but he is hopeful they can be minimized by carefully controlling the conditions under which it is run.
Image: castor beans. © United States Department of Agriculture via Wikimedia Commons