Plasmon-driven synthesis of anisotropic nanoscale gold

Abstract

[EMBARGOED UNTIL 8/1/2024] Herein, we disclose the synthesis, characterization, and application of branching gold nanostructures synthesized and tuned through plasmon-driven methods to be used in biomedical applications. The size and photothermal capability of gold nanoparticles (AuNPs) synthesized through the chemical reduction of gold salt by an aminosugar, N-methyl-D-glucamine, were tuned through irradiation by visible light during the bottom-up synthesis. Notably, the larger nanostars synthesized under red visible light showed high biocompatibility when incubated with adenocarcinoma cells, demonstrated significant photothermal conversion (n = 22.4 percent), and effectively induced hyperthermia in cancer cells upon short-term irradiation with an 808 nm NIR laser. Furthermore, we investigated the plasmon-mediated synthesis of gold nanoparticles derived from pre-reduced gold salts. Chloroauric acid was incubated with a weak reducing agent, sodium citrate, for varying durations of time before visible light irradiation and reduction by a secondary reducing agent, sodium ascorbate. Both the incubation of citrate-gold and the wavelength of the incident light were found to influence the final shape of the particles, offering morphologies suitable for applications in photothermal therapy, and cell transference. In a seeded method, we explored the utilization of pre-formed gold nanocubes as platforms for hot electron generation to synthesize branching gold nanoparticles in a plasmon-mediated method facilitated by the symmetry-breaking abilities of Ag(I). Gold was reduced onto the surface of the cube seeds through a photophysical method rather than a chemical reduction method, resulting in the first reported use of the underpotential deposition of silver in plasmon-driven synthesis of anisotropic gold nanoparticles.