All-Optical Imaging of Gold Nanoparticle Geometry Using Super-Resolution Microscopy

Area of Science:

• Nanotechnology
• Optical Microscopy
• Materials Science

Background:

• Characterizing nanoparticle geometry is crucial for understanding their properties and applications.
• Traditional methods like electron microscopy require vacuum and sample preparation, limiting in-situ analysis.
• Super-resolution microscopy offers higher resolution than light microscopy but can be limited by optical artifacts.

Purpose of the Study:

• To demonstrate an all-optical method for reconstructing gold nanoparticle geometry.
• To achieve high spatial accuracy in nanoparticle reconstruction using super-resolution techniques.
• To enable nanoparticle imaging in confined environments inaccessible to other techniques.

Main Methods:

• Utilized DNA-PAINT super-resolution microscopy for precise localization of nanoparticles.
• Optimized DNA-PAINT kinetics via complementary base number and salt concentration for ~5 nm localization accuracy.
• Employed a blue-shifted dye to minimize plasmon-fluorophore coupling artifacts.

Main Results:

• All-optical reconstructions showed less than ~10% deviation compared to atomic force microscopy.
• Numerical modeling indicated reconstruction accuracy depends on event count and signal-to-background ratio.
• Reconstructed particle orientation and aspect ratios agreed well with single-particle scattering spectroscopy.

Conclusions:

• The developed all-optical super-resolution method accurately reconstructs gold nanoparticle geometry.
• This technique overcomes limitations of traditional imaging methods in confined spaces.
• Potential applications include in-situ imaging of nanoparticles within microfluidic devices and biological cells.