Gelatin/glycerol coating to preserve mechanically compliant nanowire electrodes from damage during brain implantation

Chronically implanted neural implants are of clinical importance. However, currently used electrodes have several drawbacks. Some weeks after implantation in the brain, a glial scar forms around the electrode, causing decreased electrode functionality. Nanostructures, and in particular nanowires, are good candidates to overcome these drawbacks and reduce glial scar formation. Using a mechanically compliant substrate with protruding nanowires could further decrease the glial scar formation by reducing the mechanical mismatch between the tissue and the electrode. However, flexible substrates require strengthening upon brain implantation. One solution consists of embedding the implant in a gelatin-based matrix, which is resorbable. In the case where nanostructures are present at the surface of the implant, it is crucial that the embedding matrix also preserves the nanostructures, which can be challenging considering the forces involved during the drying phase of gelatin. Here, the authors show that freestanding gallium phosphide nanowires coated with hafnium oxide (HfO2), titanium (Ti), and gold (Au) were preserved in a gelatin-glycerol embedding matrix with subsequent implantation in 1% agar, which is a model for brain implantation.Chronically implanted neural implants are of clinical importance. However, currently used electrodes have several drawbacks. Some weeks after implantation in the brain, a glial scar forms around the electrode, causing decreased electrode functionality. Nanostructures, and in particular nanowires, are good candidates to overcome these drawbacks and reduce glial scar formation. Using a mechanically compliant substrate with protruding nanowires could further decrease the glial scar formation by reducing the mechanical mismatch between the tissue and the electrode. However, flexible substrates require strengthening upon brain implantation. One solution consists of embedding the implant in a gelatin-based matrix, which is resorbable. In the case where nanostructures are present at the surface of the implant, it is crucial that the embedding matrix also preserves the nanostructures, which can be challenging considering the forces involved during the drying phase of gelatin. Here, the authors show that freestand...

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