High-Concentration Multibranched Gold Nanoparticle Synthesis via Controllable Seeding.

Area of Science:

• Nanotechnology
• Materials Science
• Chemistry

Background:

• Multibranched gold nanoparticles exhibit localized surface plasmon resonance (LSPR) with enhanced electromagnetic fields at branch tips.
• These properties make them suitable for biological, catalytic, and spectroscopic applications.

Purpose of the Study:

• To develop a scalable, high-concentration synthesis process for multibranched gold nanoparticles.
• To achieve reproducible LSPR properties and tunable peak positions for diverse applications.

Main Methods:

• Introduced a novel sodium borohydride-free synthesis for gold nanoseeds, enabling a 10x higher concentration scale-up.
• Utilized oleate as a stabilizing agent for high-concentration seeded synthesis of multibranched gold nanoparticles.
• Demonstrated synthesis scale-up to 0.1 g Au per batch with high yield (95%).

Main Results:

• Achieved high post-synthesis gold nanoparticle concentration (2.95 mM).
• Demonstrated LSPR peak position tuning across a wide range (780-1140 nm) with high reproducibility.
• Identified an intermediary growth step involving anisotropic fragments during self-assembly.

Conclusions:

• The developed method provides a scalable route to high-quality multibranched gold nanoparticles.
• The synthesized nanoparticles are compatible with post-synthesis modifications, including capping agent exchange.
• The particles show potential for use in surface-enhanced Raman spectroscopy (SERS) sensors.