Wavelength-dependent differential interference contrast microscopy: selectively imaging nanoparticle probes in live...

Area of Science:

• Nanotechnology
• Microscopy
• Biophysics

Background:

• Gold and silver nanoparticles exhibit high apparent refractive indices near their plasmon resonance (PR) wavelengths.
• Their contrast in differential interference contrast (DIC) microscopy is strongly wavelength-dependent, leading to poor resolution at certain wavelengths.

Purpose of the Study:

• To interpret the wavelength dependence of nanoparticle contrast in DIC microscopy using Mie's theory and DIC principles.
• To develop a dual-wavelength DIC microscopy technique for simultaneous imaging and differentiation of multiple nanoparticle probes.
• To demonstrate the application of this technique for high-speed live-cell imaging with definitive probe identification.

Main Methods:

• Modification of a DIC microscope to enable simultaneous imaging at two distinct wavelengths.
• Utilizing the wavelength-dependent contrast of gold and silver nanoparticles.
• Immobilizing nanoparticles on glass slides via hybridization for differentiation.
• Recording high-contrast, video-rate images of living cells.

Main Results:

• The wavelength dependence of DIC contrast for gold/silver nanoparticles was successfully interpreted.
• Dual-wavelength DIC microscopy allowed for the differentiation and separate imaging of gold and silver nanoparticles immobilized on the same slide.
• High-contrast, live-cell imaging was achieved, with definitive identification of gold nanoparticle probes.

Conclusions:

• Dual-wavelength DIC microscopy effectively exploits the wavelength-dependent optical properties of nanoparticles.
• This technique offers a novel approach for simultaneous detection of multiple probes in high-speed live-cell imaging.
• The method provides definitive probe identification, enhancing cellular analysis capabilities.