Charlotte Mineo

Diagnosing diseases in a timely and cost-efficient way is one of the great challenges facing modern medicine. Research teams are currently investigating biosensors, as well as microelectronic sensors, in order to give clinicians greater insight into the wellbeing of their patients.

A team of researchers, including Mark Mimee, Philip Nadeau, Allison Hayward and others, published a paper in Science this week.

They and their collaborators have combined the real time results of microelectronics with the incredible specificity of biosensors.

This allowed them to create a small device capable of diagnosing upper intestinal bleeding.

The technology bridges two separate fields in diagnostic medicine and has resulted in the creation of the promising Ingestible Micro-Bio-Electronic Device (IMBED). Previous work in the separate disciplines of microelectronics and biosensors set the stage for the IMBED.

According to Mimee and other researchers from Harvard, MIT and the Boston Children’s Hospital, biosensors rely on the complex interactions between bacteria and their environments.

This approach is successful because bacteria alter their gene expression according to their environment. This improves their ability to survive.

Currently available biosensors are somewhat cumbersome.

To access the data, researchers use laboratory based tests to determine how levels of gene expression have changed. The devices aren’t yet capable of providing real time feedback.

In contrast, advances in semiconductor microelectronics have produced small devices capable of monitoring changes in pH and temperature. The gadgets can communicate this information in real time. However, in order to detect more complex health indicators, like the presence of certain molecules, the detectors would need to be far larger and more expensive.

To circumvent these issues and create the IMBED, Mimee and his team have used genetically modified E. coli and microelectronics.

The bacteria can now recognize compounds in blood and will then luminesce in their presence. An electronic detector monitors light levels. When blood is present, more light should be produced.

To create these modified bacteria, researchers inserted a genetic sequence, called a promoter, into the bacteria’s DNA.

Promoters are short sequences of DNA that determine how genes are activated in response to environmental signals.

For the IMBED, a promoter was selected that will respond to heme, a component of red blood cells.

The heme promoter then activates a gene that researchers inserted into the bacterial genome. The activated gene codes for a protein that will luminesce, creating measurable amounts of light.

As mentioned before, microelectronic sensors can measure physical parameters, like the presence of gases, temperature and even light levels.

When light is produced by the bacteria, this is measured by the electronic sensor. The raw data is rapidly transmitted to a computer outside of the body where it is further analyzed and processed.

The device was tested in pigs and was shown to be highly effective.

Once the device was swallowed by the pigs, it remained in the stomach and produced approximately five times as much light when the pigs consumed blood pills.

Unfortunately, the IMBED is eventually degraded by the acidic conditions of the stomach, but it worked smoothly over the two-hour course of the experiment.

Currently, doctors need to perform an upper endoscopy to diagnose bleeding in the upper digestive tract. With the IMBED, uncomfortable and costly procedures could be avoided.

This new research “offers opportunities to transform diagnosis, management and monitoring of health and disease,” according to Mimee’s article.

The IMBED, and similar innovative devices, are helping to create a healthier future that’s accessible for all.