HZDR team develops new approach for rapid and cost-effective detection of pathogens

In a recent publication in Biosensors and Bioelectronics (DOI: 10.1016/j.bios.2023.115701), the team describes the development of a portable, palm-sized test system that can carry out up to 32 analyses of a sample simultaneously.

There are various possibilities and mechanisms of action for detecting pathogens in body fluids. One variant that Baraban from the HZDR Institute of Radiopharmaceutical Cancer Research is researching with her team 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 electrical potential on the surface of a gate, which acts like a precise, continuous valve. Disease-relevant biomolecules bind to the gate surface and change the electrical potential and thus also the current strength. If there is no significant change in current, no biomolecules have bound to the sensor surface. Conversely, a change in the current means that disease-related biomolecules can be found on the sensor surface. These biosensors can be designed in such a way that they specifically detect different biomolecules. Different pathogens cause different electrical potentials and therefore different current strengths. Cancer cells therefore cause a different current strength than a flu virus, for example.

The disadvantage of these electronic FET-based biosensors is that the test surfaces are not recyclable and the entire transistor has to be disposed of after each sample. As these are cost-intensive semiconductor materials, this is both expensive and environmentally harmful. Baraban and her Department of Nano-Microsystems for Life Sciences therefore went one step further and tried to measure the potential changes not directly on the surface of the transistor, but on a separate electrode connected to the gate of the transistor. „This gives us the opportunity to use the transistor several times. We separate the gate and refer to it as an ‚extended gate‘ – i.e. an extension of the test system.“   

But that was not all: the team thought even further and set itself a new challenge: "Of course, we want this system to be able to perform several analyses simultaneously." The researchers succeeded in developing Extended Gates with 32 test pads. Baraban explains: „This means that a sample can be tested simultaneously on each of the pads for a different pathogen.“

The scientists first demonstrated the functionality on interleukin-6 (IL-6), a molecule that is responsible for communication between immune cells. Whether it is a simple cold or cancer, the concentration of IL-6 changes. Different diseases and also different stages of a disease produce different images. IL-6 is therefore very suitable as a marker.

Nanoparticles to increase sensitivity

In order to make the method even more sensitive, Baraban's team also utilised nanostructures. Nanoparticles concentrate or localise the charge in order to amplify the voltage signal.  „The sensitivity of the tests is significantly higher than when we work without nanoparticles.“ Since ready-made nanoparticle kits are now available on the market for research, this method is easy to use. The HZDR scientists are currently working with gold nanoparticles. In the future, they also want to investigate other nanoparticles. The result of the current research is a functional, handy test system consisting of a transistor and 32 test pads that can be used to detect different pathogens in a very short time.

In future, the test system described could be used to monitor the progress of immunotherapies in cancer patients, for example. Another possibility would be to predict the severity of a viral disease such as influenza or COVID and its progression right from the start.  Compared to existing technologies, the new test system is cheaper and faster. That is why Baraban and her team are now hoping to attract interest from industry. 

Press release of the "HZDR - Helmholtz Zentrum Dresden Rossendorf" from 07.02.2024