“We could evolve these living systems to conceivably sense any biological marker,” Mark Mimee, a graduate student at MIT and lead author of the study, tells STAT News.
The basic idea of Mimee’s pill is that bacteria glow in the presence of a particular molecule, and an adjacent electronic circuit detects the light signal and wirelessly transmits it to a cell phone. For this proof-of-concept demonstration, Mimee and his colleagues engineered E. coli to bioluminescence when they encounter the compound heme, an indicator of bleeding, in the guts of pigs. Packaged within a capsule 1.5 inches in length, the bacteria and electronics alerted the researchers to bleeding with the pigs’ guts within an hour of the pills being inserted with a tube, and kept transmitting data for two hours.
“A lot of important biology and health-related pathways are happening there, and we don’t have really good technologies to see inside the gut and measure chemicals there,” Jeff Tabor, a bioengineer at Rice University who was not involved in the study, tells STAT. “Getting the data back out is a challenge, so having a convenient, really practical strategy for having the bacteria tell us what they see is important.”
The researchers envision that such probiotic sensors could be developed to monitor the goings-on within organisms long-term, to pick up on multiple molecular signals simultaneously, and to be smaller.