Researchers reported in the journal ACS Sensors that they have developed a sensor made of small microspheres, filled with blood-sensitive bacteria, that detects signs of digestive system diseases, which could replace the need for colonoscopy in the future.
According to the Medical Xpress website, these mini-pills, when taken orally, contain magnetic particles that facilitate their collection from the stool, as they were tested on mice.
The importance of new technology
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The researchers noted that once these pills were removed from mouse models of colitis, the bacterial sensor detected intestinal bleeding within minutes, and the bacteria in the sensor could be modified to detect other intestinal diseases.
“This technology provides a new paradigm for rapid, non-invasive detection of gastrointestinal diseases,” says Ying Zhu, one of the study’s co-authors.
The difference between the new technology and current colonoscopy methods
In the United States, millions of people have colorectal cancer or inflammatory bowel disease, including colitis, which may cause intestinal bleeding, diarrhea and cramping. The standard diagnosis is colonoscopy using an endoscope, a device with a camera at the end of a long wire passed through the large intestine.
Despite its clinical importance, many avoid this procedure due to its preparation and complexity, but the research team is working to develop gentler methods using bacteria that sense biomarkers of disease, such as heme, a component of red blood cells, which is a sign of gastrointestinal bleeding.
How does the new bacteria sensor work?
Previously, researchers have developed heme-sensitive bacteria that light up in the presence of blood, but these bacterial sensors break down in the digestive tract and are difficult to collect. In this current study, they encapsulated their heme-detecting bacteria and magnetic particles inside balls of sodium alginate, a thickener used in foods.
This process produces tiny spherical hydrogel sensors, which can be easily removed from stool using a magnet after passing through the body. Preliminary tests have shown that the hydrogel protects bacteria from simulated digestive fluids, but also allows heme to interact with the bacterial sensor, making it glow.
Testing of the sensor in animal models
Next, the team administered the microbeads orally to mouse models of colitis, representing levels of the disease from inactive to severe stages. After the microbeads passed through the animals’ digestive tracts, the researchers retrieved the sensors from feces using a magnet, and found:
Cleaning the microsphere and analyzing the signal took about 25 minutes
As the disease progressed, the intensity of the light produced by the sensor increased, indicating that more heme was present in mouse models of more advanced colitis.
Evaluations in healthy mice fitted with the sensor indicated that the microspheres are biocompatible and safe, and although the sensor still needs to be tested in humans, researchers say this method of encapsulating bacterial sensors could help diagnose gastrointestinal diseases and monitor treatments and disease progression.
