A new approach for rapid and cost-effective detection of pathogens

The ability to detect diseases at an early stage, or even predict their onset, would be of immense benefit to doctors and patients alike. A research team led by Dr. Larysa Baraban from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) is developing intelligent, miniaturized biosensor devices and systems using nanomaterials to determine biomolecules and cells as well as biochemical reactions or processes as markers of illness.

The team’s current publication in Biosensors and bioelectronics describes the development of a portable, palm-sized testing system that can simultaneously perform up to 32 analyzes of a sample.

There are various possibilities and mechanisms to detect pathogens in body fluids. One option that Baraban is studying at the HZDR Institute for Radiopharmaceutical Cancer Research is detection using field-effect transistors (FETs) from the field of electronics.

The operating principle is simple: a defined electric current flows from A to B. This current can be regulated by the electric potential on the surface of a gate, which functions like a precise and continuous valve.

Disease-related biomolecules bind to the surface of the gate and thus modify the electrical potential and therefore also the current. If there is no significant change in current, no biomolecules have bound to the sensor surface. On the other hand, a change in current means that disease-related molecules can be detected on the sensor surface.

These biosensors can be designed to specifically detect different biomolecules. Different pathogens cause different electrical potentials and therefore different currents. Cancer cells cause different currents than, say, a flu virus.

Development of reusable transistors

The major drawback of traditional FET-based electronic biosensors is that the test surfaces are not reusable and the entire transistor must be discarded after each sampling. As transistors contain expensive semiconductor materials, this process is both expensive and harmful to the environment.

For this reason, Baraban and his department of nano-microsystems for life sciences went further and attempted to measure potential changes not directly on the surface of the transistor, but on a separate electrode connected to the gate of the transistor. transistor. “This gives us the ability to use the transistor multiple times. We separate the gate and call it an ‘extended gate,’ that is, an extension of the test system.”

But that’s not all. The team thought even further and took on another challenge. “Of course we want this system to be able to perform several analyzes at the same time.” The researchers successfully developed extensive gates with 32 test ranges. Baraban explains: “This means that a sample can be tested simultaneously on each of the pads to detect a different pathogen. »

Scientists first demonstrated the working principle using interleukin-6 (IL-6), a molecule responsible for communication between immune cells. “Whether it’s a common cold or cancer, the concentration of IL-6 changes. Different diseases as well as different stages of a disease produce different clinical pictures. This is why IL -6 is very well suited as a marker.”

Nanoparticles to increase sensitivity

To make the method even more sensitive, Baraban’s team also used nanostructures. The nanoparticles concentrate or localize the charge to amplify the voltage signal.

“The sensitivity of the tests is considerably higher than when we work without nanoparticles.” As ready-to-use nanoparticle kits for research are now available on the market, this method is simple to use. HZDR scientists are currently working with gold nanoparticles. In the future, they would also like to study other nanoparticles.

Thanks to current research, a functional and practical test system has been created, consisting of a transistor and thirty-two test pads, with which different pathogens can be detected in a very short time.

In the future, the described testing system could, for example, be used to monitor the progress of immunotherapies in cancer patients. Another possibility would be to predict from the start the severity and course of a viral illness such as influenza or COVID-19.

Compared to existing technologies, the new system is more cost-effective and faster. That’s why Baraban and his team now hope to attract interest from the commercial sector.