Multispectral Interferometric Scattering Microscopy Imaging of Gold and Silver Nanoparticles.

Area of Science:

• Nanotechnology
• Optical Microscopy
• Plasmonics

Background:

• Noble metal nanoparticles (NPs) possess tunable optical properties due to localized surface plasmon resonances.
• These resonances are sensitive to NP size, shape, and composition, enabling their use as multi-color labels.
• Optical sensing and imaging benefit from labels with distinct spectral characteristics.

Purpose of the Study:

• To apply three-color interferometric scattering microscopy (iSCAT) for imaging gold (Au) and silver (Ag) nanoparticles.
• To investigate the wavelength-dependence of iSCAT contrast for individual nanoparticles.
• To assess the potential for distinguishing NPs based on spectral information for multiplexed applications.

Main Methods:

• Utilized three-color iSCAT with detection channels at 405 nm, 445 nm, and 520 nm.
• Imaged Au and Ag NPs with diameters ranging from 5 nm to 60 nm.
• Analyzed the spectral contrast of individual NP scatterers.

Main Results:

• Demonstrated the ability to obtain multispectral iSCAT contrast for individual Au and Ag NPs.
• Showcased selectivity in distinguishing NPs of the same metal but different sizes.
• Achieved distinction between NPs of the same size but different metals based on spectral signatures.

Conclusions:

• Multispectral iSCAT provides valuable spectral information for NP characterization.
• This approach enhances the ability to differentiate nanoparticles with varying properties.
• The spectral gain in iSCAT opens possibilities for multiplexed optical sensing and imaging using NP labels.