Bimetallic core-shell nanoparticles with tunable core diameter and shell thickness are unique nanomaterials with controllable optical properties and atomic ratios, of interest for plasmonic studies and as highly-characterized constructs for single particle elemental analysis.
Bimetallic Au-core/Ag-shell nanospheres are available in size ranging from 20 to 80 nm in diameter. The particles are stabilized with sodium citrate (2 mM) and are provided at 0.05 mg/mL or 1 mg/mL (total metal content).
Total Diameter (nm)
Gold Core Diameter (nm)
Silver Shell Thickness (nm)
Au Mass %
Ag Mass %
Plasmon Resonance Peak (nm)
Due to the unique optical properties of gold and silver, the bimetallic nanoparticles have a tunable peak resonance wavelength that is a function of the size of the gold core and the thickness of the silver shell.
The optical properties of the bimetallic particles are different than for solid silver or solid gold of the same diameter. Normalized UV-visible extinction spectra for bimetallic and solid silver and gold nanoparticles are shown below.
Toxicologist have performed hundreds of studies on our silver nanoparticles to understand how the size, shape, and surface of silver nanoparticles affects the environment and human health. Bimetallic Au@Ag nanoparticles are an additional tool to understand fate and transport in biological systems by providing definitive information about the dissolution state and ultimate fate of the particles. Transmission Electron Microscopy images in tissue slices can show the rate of structure of silver dissolution as well as locate the gold core which will remain intact during experiments. ICP-MS analysis can measure the ratio of silver to gold, providing additional information on dissolution rates and nanoparticle fate and transport.
Single Particle ICP-MS
Bimetallic nanomaterials can be used as standards or tracer materials in single particle inductively coupled plasma mass spectroscopy (SP-ICP-MS) studies. Our highly uniform samples contain particles with low particle-to-particle variation in the Au:Ag ratio. Further, during dissolution studies where some of the silver may dissolve into solution, the more stable gold core provides a constant mass signal that can be used to help determine particle size and a check of the starting particle concentration in a sample.