Ingestible “bacteria on a chip” could help diagnose disease
This “bacteria-on-a-chip” approach combines sensors made from living cells with ultra-low-power electronics that convert the bacterial response into a wireless signal that can be read by a smartphone. In the new study, appearing in the May 24 online edition of Science, the researchers created sensors that respond to heme, a component of blood, and showed that they work in pigs. They also designed sensors that can respond to a molecule that is a marker of inflammation.
In the past decade, synthetic biologists have made great strides in engineering bacteria to respond to stimuli such as environmental pollutants or markers of disease. These bacteria can be designed to produce outputs such as light when they detect the target stimulus, but specialized lab equipment is usually required to measure this response. To make these bacteria more useful for real-world applications, the MIT team decided to combine them with an electronic chip that could translate the bacterial response into a wireless signal.
For their initial demonstration, the researchers focused on bleeding in the GI tract. They engineered a probiotic strain of E. coli to express a genetic circuit that causes the bacteria to emit light when they encounter heme. The researchers tested the ingestible sensor in pigs and showed that it could correctly determine whether any blood was present in the stomach.
They anticipate that this type of sensor could be either deployed for one-time use or designed to remain the digestive tract for several days or weeks, sending continuous signals.