Researchers have developed tiny ingestible hydrogel microspheres packed with engineered bacteria that glow when they encounter blood in the gut, potentially offering a quick, noninvasive way to monitor intestinal disease. In mouse models of colitis, the sensors detected heme — a component of blood — within minutes and produced stronger signals as disease severity increased.
Gastrointestinal diseases, including colorectal cancer and inflammatory bowel disease such as colitis, affect millions of people in the U.S. and can cause intestinal bleeding, diarrhea and abdominal cramping. The current gold-standard diagnostic for many lower gastrointestinal conditions is colonoscopy, in which an endoscope with a camera is threaded into the large intestine. Despite its clinical value, the invasiveness of the procedure and the bowel preparation it requires lead some patients to avoid it, according to the American Chemical Society.
To explore a gentler approach, researchers including Ying Zhou, Bang-Ce Ye and Zhen-Ping Zou have helped develop bacterial sensors that emit light when they detect heme, a red blood cell component that signals intestinal bleeding. Earlier versions of these bacterial sensors tended to break down in the digestive tract and were difficult to recover after passing through the body.
In the new work, reported in ACS Sensors, the team enclosed their engineered, heme-sensing bacteria together with magnetic particles inside small droplets of sodium alginate, a thickening agent widely used in foods. This process produced robust hydrogel microspheres that could travel through the gastrointestinal tract. In laboratory tests using simulated digestive fluids, the hydrogel coating protected the bacteria while still allowing heme to reach them and trigger a glow signal.
The researchers then administered the microspheres orally to mouse models of colitis representing disease activity from none to severe. After the microspheres passed through the animals’ intestines, the team retrieved the particles from feces using a magnet. Cleanup and signal analysis took roughly 25 minutes. In these experiments, the sensors produced brighter light signals in mice with more advanced colitis, indicating higher levels of heme, while tests in healthy mice suggested that the microspheres were biocompatible and did not cause obvious harm.
“This technology provides a new paradigm for rapid and non-invasive detection of gastrointestinal diseases,” said Ying Zhou, a co-author of the study, in a statement released by the American Chemical Society.
The study, titled “Magnetic Hydrogel: Enhanced Bacterial Biosensor for Speedy Gut Disease Detection,” appears in ACS Sensors (2025; DOI: 10.1021/acssensors.5c01813). According to ACS and ScienceDaily’s report on the work, the encapsulated bacterial microspheres have not yet been tested in humans, but the researchers say that similar sensors could eventually help diagnose gastrointestinal diseases, monitor patients’ responses to treatment and track changes in disease over time. The authors acknowledge funding from the National Natural Science Foundation of China, the National Key Research and Development Program of China and the China Postdoctoral Science Foundation.
At this stage, experts emphasize that the findings are based on animal studies, and further research would be required to determine whether such bacterial “pills” could one day serve as a practical complement or alternative to some colonoscopy-based assessments in clinical practice.
