Facile and Scalable Synthesis of Whiskered Gold Nanosheets for Stretchable, Conductive, and Biocompatible Nanocomposites

Abstract

Noble metal nanomaterials have been studied as conductive fillers for stretchable, conductive, and biocompatible nanocomposites. However, their performance as conductive filler materials is far from ideal because of their high percolation threshold and low intrinsic conductivity. Moreover, the difficulty in large-scale production is another critical hurdle in their practical applications. Here we report a method for the facile and scalable synthesis of whiskered gold nanosheets (W-AuNSs) for stretchable, conductive, and biocompatible nanocomposites and their application to stretchable bioelectrodes. W-AuNSs show a lower percolation threshold (1.56 vol %) than those of gold nanoparticles (5.02 vol %) and gold nanosheets (2.74 vol %), which enables the fabrication of W-AuNS-based stretchable nanocomposites with superior conductivity and high stretchability. Addition of platinum-coated W-AuNSs (W-AuNSs@Pt) to the prepared nanocomposite significantly reduces the impedance and improved charge storage capacity. Such enhanced performance of the stretchable nanocomposite enables us to fabricate stretchable bioelectrodes whose performance is demonstrated through animal experiments including electrophysiological recording and electrical stimulation in vivo.

Highly conductive and stretchable hydrogel using a percolated network of whiskered gold nanosheets

“…Since W-AuNSs have whiskered morphology and nanometer range thickness 34 , they become highly interconnected but maintain a porous structure when they are dried from the dispersed solution state. As a result, the density of the dried W-AuNSs (i.e., W-AuNS network) is lower than the density of the dried forms of conventional metal nanomaterials such as silver nanowires (AgNWs) and gold nanosheets (AuNSs) (Extended Data Figs.…”

“…Preparation of metal nanomaterials W-AuNSs, AgNWs and AuNSs were synthesized by using the previously reported methods 26,34 .…”

“…Conductivity of the composite can be increased by raising the weight fraction of the conductive component 34 . To enhance the conductivity of the wAu-CSHs, we increased the fraction of W-AuNSs through the pressing process.…”

Challenges and Opportunities of Implantable Neural Interfaces: From Material, Electrochemical and Biological Perspectives

“…Lim et al. [ 122 ] reported a facile and scalable synthesis approach to preparing whiskered Au nanosheets (W‐AuNS)‐based bioelectrode via in‐situ reaction, combined with the medical‐grade thermoplastic polyurethane (TPU) surface. After further modification with Pt, the W‐AuNS@Pt nanocomposites exhibited a large CSC c of 82 mC cm −2 and a significantly reduced impedance in the low‐frequency region.…”

“…Moreover, the innovative mechanically tissue-like and highly conductive AuNPs embed elastomeric fiber electrodes demonstrated high SNRs of 3.1-4.2, and extremely reliable impedance over four months postimplantation (<20% variation) with reduced foreign body responses, thus encouraging a new paradigm of chronic recording and promoting better understanding the neural interfaces. Lim et al [122] reported a facile and scalable synthesis approach to preparing whiskered Au nanosheets (W-AuNS)-based bioelectrode via in-situ reaction, combined with the medical-grade thermoplastic polyurethane (TPU) surface. After further modification with Pt, the W-AuNS@Pt nanocomposites exhibited a large CSC c of 82 mC cm −2 and a significantly reduced impedance in the low-frequency region.…”