Enzyme-free in situ polymerization of conductive polymers catalyzed by porous Au@Ag nanowires for stretchable neural electrodes

TL;DR

This paper introduces a novel enzyme-free in situ polymerization method for conductive polymers using porous Au@Ag nanowires with catalytic properties, enabling safer, controlled growth on stretchable neural electrodes.

Contribution

It presents the first enzyme-free catalytic approach for in situ polymerization of conductive polymers using porous Au@Ag nanowires, operating under mild, near-neutral conditions.

Findings

Achieved conductive polymer coating with low impedance of 2.6 kOhm at 1 kHz.

Demonstrated polymerization both in aqueous dispersion and on stretchable electrodes.

Improved electrode electrical performance through in situ polymerization.

Abstract

In situ polymerization of conductive polymers (CPs) represents a transformative approach in bioelectronics, by enabling the controlled growth of electrically active materials right at the tissue or device surface to create seamless biotic-abiotic interfaces. Traditional CP deposition techniques often use high anodic potentials, non-physiological electrolytes, or strong oxidants, making them harmful to adjacent tissues. A possible solution is enzymatic polymerization which operates under milder conditions, but it is limited by the stability and activity window of the enzyme catalysts, low throughput, and challenges in spatially confining polymer growth. To resolve these issues, here we developed one-dimensional porous Au-coated Ag nanowires with horseradish peroxidase (HRP)-like catalytic properties, thereby for the first time enabling mild in situ enzyme-free polymerization of conductive polymers near neutral pH. The enzyme-free polymerization is demonstrated both in aqueous dispersions at pH=6 and in situ onto porous Au coated Ag nanowire based stretchable electrodes. Following enzyme-free catalytic polymerization, the electrically conducting polymer coating on the electrode greatly improves the impedance and achieves an impedance of 2.6 kOhm at 1 kHz for 50x50 um large electrodes.