Flexible and stretchable nanowire-coated fibers for optoelectronic probing of spinal cord circuits

Science Advances, 2017 · DOI: 10.1126/sciadv.1600955 · Published: March 29, 2017

Simple Explanation

The study introduces a new type of probe for studying spinal cord injuries. These probes are flexible and can stretch, making them suitable for use in the spinal cord, which moves during normal activity. The probes combine optical stimulation with electrophysiological recording. This allows researchers to both stimulate and record neural activity in the spinal cord. The probes are made from polymer fibers coated with silver nanowires. This design allows for low optical transmission losses and impedance suitable for extracellular recording.

Study Duration

Up to 1 week

Participants

Thy1-ChR2-YFP transgenic and WT mice

Evidence Level

Not specified

Key Findings

1
The nanowire-coated fiber probes maintained optical and electrical properties under bending and stretching deformations.
2
The probes were able to record spontaneous neural activity, sensory-evoked potentials, and optically evoked spinal potentials.
3
Optical stimulation through the probes resulted in muscle contractions in the hindlimb, demonstrating the ability to control neural activity.

Research Summary

The study reports on the development of flexible and stretchable probes for optoelectronic probing of spinal cord circuits in mice, combining thermal drawing of polymer fibers with solution-deposited nanowires. The probes demonstrated resilience to bending and stretching, maintaining optical and electrical properties under deformations experienced by the mouse spinal cord during normal motion. In vivo experiments showed the probes' capability to record spontaneous neural activity, sensory-evoked potentials, and optically evoke spinal potentials, suggesting their potential for monitoring and controlling neural activity to promote recovery following spinal cord injury.

Practical Implications

Spinal Cord Injury Treatment

The probes may allow for monitoring and controlling of neural activity to promote recovery following spinal cord injury.

Visceral Organ Neurophysiology

The fibers may be tailored to address fundamental questions in spinal cord or visceral organ neurophysiology.

Drug Delivery

Additional chemical stability can be achieved through covalent cross-linking of the mesh, and the surface of the exposed NW ring can be passivated through electrodeposition of gold or iridium oxide layers via established protocols routinely applied to nickel-chromium (Ni/Cr) tetrodes.

Study Limitations

1
Isolating single-neuron action potentials from the mouse spinal cord during free behavior remains a goal because such recordings are exceedingly difficult
2
Recordings from freely moving mice contained a combination of multiunit activity and movement artifacts and were confounded by greater noise levels than those performed under anesthesia.
3
Conceptual experiments conducted with AgNW meshes as electrodes within fiber probes do not reveal tissue erosion or cytotoxic effects in the vicinity of the implants.

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