Gold coating could reduce scarring.

A team of scientists from Lawrence Livermore National Laboratory, Livermore, CA, working with other researchers at the University of California, Davis, say that covering an implantable neural electrode with nanoporous gold could eliminate the risk of scar tissue forming over the electrode’s surface.

Fig. 1 – The image depicts a neuronal network growing on a novel nanotextured gold electrode coating. (Credit: Ryan Chen/LLNL)
The team demonstrated that the nanostructure of nanoporous gold achieves close physical coupling of neurons by maintaining a high neuron-to-astrocyte surface coverage ratio. Close physical coupling between neurons and the electrode, they explain, plays a crucial role in recording fidelity of neural electrical activity.

Neural interfaces, also known as implantable electrodes or multiple-electrode arrays, are being used to monitor and modify neural electrophysiology, both for fundamental studies of the nervous system, and to diagnose and treat neurological disorders. These interfaces require low electrical impedance to reduce background noise and close electrode-neuron coupling for enhanced recording fidelity.

But, designing neural interfaces that maintain robust physical coupling of neurons to an electrode surface remains a major challenge for both implantable and in vitro neural recording electrode arrays. One obstacle the team found is encapsulation of the electrode by scar tissue.

Typically, low-impedance nanostructured electrode coatings rely on chemical cues from pharmaceuticals or surface-immobilized peptides to suppress glial scar tissue formation over the electrode surface.

However, the team discovered that nanoporous gold, produced by an alloy corrosion process, could reduce scar tissue formation on the electrode surface solely through topography by taking advantage of its tunable length scale. Their results show that nanoporous gold topography, not surface chemistry, reduces astrocyte surface coverage.

Nanoporous gold features high effective surface area, tunable pore size, well-defined conjugate chemistry, high electrical conductivity, and compatibility with traditional fabrication techniques.

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