l-Ergothioneine promotes the formation of long gold nanowires and their 2D assembly

Abstract

Gold nanowires with large aspect ratios, renowned for their exceptional mechanical properties, geometry-dependent conductance, and distinct plasmon peaks, are promising for applications in plasmonics, sensors, nanoelectronics, catalysis, and wearable optoelectronics. Traditional synthesis methods, such as lithography and template-assisted electrodeposition, often involve complex procedures or require seeding steps, making them less suitable for scalable integration into wearable optoelectronic devices. Here, we report a seedless and aqueous synthesis of gold nanowires (15–40 nanometers in diameter and 10–20 micrometers in length) at room temperature, utilizing natural amino acid L-ergothioneine (EGT) and quaternary alkylammonium halides (CTAX) as structure-directing agents and ascorbic acid (AA) as a redox agent. We propose that EGT plays a multifaceted role in the synthesis of gold nanowires. It likely facilitates the ligand exchange of CTAX–gold(III) complexes and promotes the formation of EGT–gold(I) species during AA reduction. Additionally, as the ligand of gold(I), EGT could interact with CTA⁺, thereby modifying micellar structures and directing the anisotropic growth of gold. Moreover, EGT-assisted gold nanowires exhibit diverse 2D assembled structures. For instance, surface property-controlled assembly on polypropylene membranes yields a gold nanowire mat, while the presence of iodide ions induces the formation of various leaf-like assemblies. Both 2D configurations extend over several to tens of micrometers, making them highly beneficial for the further development of flexible electronic skin. This study highlights the potential of EGT as a versatile directing agent and underscores the importance of the reaction environment in controlling the morphology and assembly of gold nanowires, offering new avenues for the controlled fabrication of gold nanostructure-based wearable optoelectronic devices.