Imaging single chiral nanoparticles in turbid media using circular-polarization optical coherence microscopy

Area of Science:

• Biomedical Optics
• Nanotechnology
• Molecular Imaging

Background:

• Optical coherence tomography (OCT) is a powerful structural imaging technique but lacks contrast for molecular imaging.
• Gold nanoparticles, used for molecular probes via Surface Plasmon Resonance (SPR), offer weak contrast in OCT imaging of biological tissues.
• Conventional nanoparticle imaging in thick tissues with OCT is challenging, with sensitivity lower than fluorescence imaging.

Purpose of the Study:

• To develop a novel approach for significant contrast enhancement in optical coherence microscopy for molecular imaging.
• To overcome the limitations of conventional OCT in imaging nanoparticles within biological tissues.

Main Methods:

• Utilized a circular-polarization optical coherence microscopy system.
• Employed 3-dimensional chiral nanostructures as contrast agents.
• Detected circular intensity differential depolarization (CIDD) for signal amplification.

Main Results:

• Achieved remarkable contrast enhancement for molecular imaging.
• Successfully acquired high-quality images of single chiral nanoparticles.
• Demonstrated imaging capability underneath a 1-mm-thick tissue-mimicking phantom.

Conclusions:

• The developed method, combining chiral nanostructures and circular-polarization OCT, significantly improves contrast for molecular imaging.
• This novel approach enables sensitive detection of nanoparticles in thick tissues, surpassing conventional OCT limitations.
• The technique holds promise for advanced molecular imaging applications in biological and biomedical research.