Miniature Biosensor Uses Nanomaterials to Detect Biomolecules, Pathogenic Cells in Body Fluids

Detecting diseases early or even predicting their onset would benefit doctors and patients alike. In a new study, experts developed a portable test system for determining biomolecules and cells as disease markers.

Limitations of FET-Based Biosensors

Different approaches and mechanisms are used to detect pathogens in human body fluids. One is the use of field-effect transistors (FET), a transistor that uses an electric field to control the flow of current in a semiconductor.

Using field-effect transistors operates on a simple principle. As a defined electrical current flows from A to B, it is regulated by the electrical potential on the surface of a gat,e, which works like a precise, continuous valve.

Biomolecules related to diseases bind to the gate surface and change the electrical potential and the current. If no significant change happens in the current, no biomolecule is expected to attach to the sensor's surface.

Meanwhile, a change in the current means that disease-related biomolecules can be detected on the sensor surface. This means the biosensors can be designed to detect various biomolecules specifically. Each pathogen can cause a different electrical potential and, therefore, different currents. For instance, cells can be current, which differs from the one created by a flu virus.

Harnessing Potential of Reusable Transistors

Despite its effectiveness, there is a major disadvantage in using traditional electronic biosensors based on field-effect transistors. Since the test surfaces are not reusable, the entire transistor must be discarded after each sampling process. Transistors contain expensive semiconductor materials, so this process is costly and harmful to the environment.

At the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), a research team led by Dr Larysa Baraban went one step further. In collaboration with her colleagues at the Department of Nano-Microsystems for Life Sciences, they tried to measure the potential changes on the surface of the transistor. It was not done directly but on a separate electrode connected to the transistor's gate. The result of their investigation is described in the paper "Methods gold standard in clinic millifluidics multiplexed extended gate field-effect transistor biosensor with gold nanoantennae as signal amplifiers."

The research team separated the gate and used it as an extension of the test system, referred to as an 'extended gate.' This enabled them to use the transistor multiple times. Aside from this, the experts also succeeded in developing extended gates with 32 test pads.

The team utilized nanostructures that concentrate the charge to amplify the voltage signal to make the method more sensitive. It was found that the test's sensitivity is significantly higher than when experts work without nanoparticles.

The new test system consisting of a transistor and 32 test pads was found to be a functional approach to detecting various pathogens quickly. The HZDR team currently works with gold nanoparticles. In the future, they plan to study other types of nanoparticles. When compared to existing technologies, the new system is cheaper and faster. Because of this, Baraban and her team hope their work will gain interest from the commercial sector.

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