Bacterial sensors: a technological marriage at the service of the gastrointestinal tract

An American team has designed a biosensor composed of a synthetic bacterium and an electronic circuit, opening up a vast new field of research in which the most minute changes taking place in the human gastrointestinal tract are detected.

 

In the age of self-monitoring and nanorobots, biosensors are king. Increasingly sophisticated, they could become more so if they could acquire the detection power of bacteria. An American team has developed a new ingestible microbiological device (IMBED): a sort of “bacterial sensor”, which promises unprecedented insights into the life and diseases of our gastrointestinal tract.

Bacteria, light and WiFi

To prove their concept, the researchers designed a prototype containing a bacterium intended to detect potential gastrointestinal bleeding. The novelty of this capsule resides in its semipermeable membranes which are able to identify molecules that diffuse into it. A bacterium which is commonly manipulated in the laboratory (Escherichia coli) was modified by genetic engineering and placed within this capsule and then linked to an electronic circuit. The principle is quite simple: on contact with blood, the bacterium emits light, which is detected by the electronic component, which then transmits the information wirelessly to a device–a smartphone for example.

Successful tests in vitro and in vivo

Tested successfully in vitro on horse blood and human blood, then in rodents (in which a gastrointestinal hemorrhage was triggered), the bacterial sensor was subsequently inserted into the stomach of three pigs which had previously ingested a blood solution. It was a success: the first light measurements, proportional to the quantity of blood detected, were indeed displayed rapidly on the computer and smartphone of the experimenters.

A sensor that can still be perfected

It remains to be discovered how best to encapsulate this bacterial biosensor so as to allow it to remain in the gastrointestinal tract for an extended time period, in particular to resist the very acidic environment of the stomach, to reduce its size (around 3 cm in length) or to guide it to very targeted locations in the gastrointestinal tract. As the bacterium can be adapted to detect inflammation or infection markers as well, its potential is enormous: diagnosis, research, real-time monitoring of the efficacy of treatments or patient compliance… And why not the emergence of an intestinal “quantified self”?

 

Sources:

M Mimee et al. An ingestible bacterial-electronic system to monitor gastrointestinal health, Science 25 May 2018