TU Dresden: New material from Dresden for bioelectronics: Conductive hydrogel controls electrical and biochemical signals

Under the leadership of Prof. Ivan Minev (Technische Universität Dresden (TUD), Leibniz Institute of Polymer Research Dresden) and Dr. Christoph Tondera (Leibniz Institute of Polymer Research Dresden and Center for Regenerative Therapies (CRTD) at TUD), researchers have now succeeded in developing such a material. The bio-inspired hydrogel combines biochemical and electrical signal control for the first time. It binds messenger substances that stimulate cells to grow and can release them again in a targeted manner using electrical impulses. It also serves as a sensor to measure biological parameters such as oxygen. The approach opens up new possibilities for medical devices and implants, for example for treating damage to the nervous system. The results were published in the journal Advanced Materials.

A material modeled on nature

In order for implants to be well tolerated by the human body, their mechanical properties must be similar to those of the surrounding tissue. For applications in the nervous system, this means that ideal materials should be soft, flexible and at the same time electrically conductive. Based on the natural cell environment (extracellular matrix – ECM), the researchers developed a water-based material (hydrogel) that mimics key properties of the ECM and is also electrically active. One component of the ECM is glycosaminoglycans, which consist of strongly negatively charged, long-chain sugar molecules. The researchers combined these with star-shaped polyethylene glycol (starPEG) to form a three-dimensional network that can bind water and other substances. They then supplemented this bio-inspired hydrogel with the semiconducting organic polymer PEDOT. The integration of the conductive polymer ultimately resulted in a new, promising material (PEDOT:sGAGh) that is suitable for applications at the interface of biomedicine and electronics.

Conductive, controllable and biologically active

In a series of experiments, the researchers showed that PEDOT becomes embedded in the hydrogel without destroying its nanostructure. Small conductive clusters were formed within the material, which can transmit electrical signals. At the same time, the material remains soft and water-based – properties that are crucial for use in the body. The electrical conductivity can be specifically adjusted, for example via the amount of PEDOT and the number of negative charges in the material. The researchers then tested whether bioactive molecules can also be bound in the material and released again. This is relevant for implants, for example, which are intended to release active substances in the body in addition to electrical stimulation. “With the help of weak electrical signals, we can specifically control whether growth factors remain bound in the material or are released. Our cell culture experiments show that the factors are not altered by the electrical stimulation and remain biologically active: After controlled release of the growth factor VEGF, the cultured cells formed tube-like structures – an early stage of blood vessel formation,” explains Dr. Teuku Fawzul Akbar, scientist in Prof. Minev’s group and first author of the publication.

In addition to releasing signaling substances, the material can also serve as a sensor. The team demonstrated this by measuring oxygen. The researchers demonstrated this in a biohybrid circuit: If the oxygen content drops, an electrical signal is triggered that controls the release of a growth factor. This in turn can stimulate the growth of nerve cells in the cell culture. “Our material is the first to combine the soft properties of biological tissue with its natural mode of communication: signal transmission via biomolecules and electrical impulses. This is an important step for the development of new biomedical devices and implants,” says Dr. Christoph Tondera, research group leader at the Leibniz Institute of Polymer Research Dresden and the CRTD at TUD.

Better brain-computer interfaces and smart implants

The hydrogel transfers a principle from nature to technology by combining biochemical signaling with electrical control. In the future, the material could be used in electrode coatings or bioelectronic components, for example. In the long term, the technology should help to improve interfaces between the brain and computer. One conceivable medical application is brain implants that not only measure or stimulate, but combine both. This could improve treatment for patients with epilepsy or Parkinson’s disease. “Next, we will test the long-term stability, performance and tolerability of our material. The aim is to develop a prototype as quickly as possible and test it under clinical conditions,” says Prof. Ivan Minev, who heads the Electronic Tissue Technologies professorship at the Else Kröner Fresenius Center (EKFZ) for Digital Health at the TUD and the Leibniz Institute of Polymer Research Dresden. In a first step, Prof. Minev’s team is already working on the COATARRAY project with neurosurgeons from Dresden University Hospital. Existing electrodes for deep brain stimulation are to be further developed on the basis of the new material.

Research institutions involved and funding

The Electronic Tissue Technologies professorship is based at the EKFZ for Digital Health at the TUD and the Leibniz Institute of Polymer Research (Leibniz-IPF) Dresden. Scientists from the Dresden Integrated Center for Applied Physics and Photonic Materials (DC-IAPP), the Center for Regenerative Therapies (CRTD) at the TUD and the Max Planck Institute of Colloids and Interfaces in Potsdam were also involved in the research. The work was funded by the European Research Council (ERC) and the German Research Foundation (DFG).

This press release has been automatically translated. 

_ _ _ _ _ _
Further links

👉 To the original announcement

👉 Else Kröner Fresenius Center (EKFZ) for Digital Health

👉 Leibniz Institute of Polymer Research Dresden (Leibniz-IPF)

👉 Publication for download