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Published on: February 9, 2019
Au nanorings for enhancing absorption and backscattering monitored with optical coherence tomography
Hung-Yu Tseng1, Cheng-Kuang Lee, Shou-Yen Wu
1Institute of Photonics and Optoelectronics, and Department of Electrical Engineering, National Taiwan University, No 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan, Republic of China.
Gold nanorings (Au NRs) in water enhance optical coherence tomography (OCT) imaging contrast and create photothermal effects in biological samples. These Au NRs improve deep tissue imaging and make opaque tissues transparent via localized surface plasmon resonance.
Area of Science:
- Nanotechnology
- Biomedical Optics
- Materials Science
Background:
- Optical Coherence Tomography (OCT) is a valuable imaging technique, but its contrast and penetration depth can be limited in biological tissues.
- Localized Surface Plasmon (LSP) resonance in metallic nanoparticles offers potential for enhancing optical properties of materials.
Purpose of the Study:
- To prepare a high-concentration gold nanoring (Au NR) water solution for enhanced OCT imaging and photothermal applications.
- To investigate the use of Au NRs for improving image contrast and generating photothermal effects in bio-samples via LSP resonance.
Main Methods:
- Fabrication of Au NRs on a sapphire substrate using colloidal lithography and sputtering, followed by a liftoff process into water.
- Tuning the geometry of Au NRs to achieve LSP dipole resonance within the 1300 nm spectral range for deep tissue OCT scanning.
- Delivery of Au NRs into pig adipose tissue samples for OCT imaging and analysis of photothermal and contrast enhancement effects.
Main Results:
- Au NRs in water exhibited extinction cross sections of 10(-10)-10(-9) cm(2) near their LSP resonance wavelengths.
- In pig adipose tissue, Au NRs induced a photothermal effect, rendering opaque cells transparent.
- Au NRs enhanced OCT image contrast through LSP resonance-enhanced scattering in the intercellular substance.
Conclusions:
- High-concentration Au NR water solutions can be effectively prepared for biomedical optics applications.
- Au NRs demonstrate dual functionality in OCT: enhancing image contrast and inducing photothermal effects via LSP resonance.
- The observed effects depend on OCT scanning parameters, with continuous scanning revealing both photothermal and contrast enhancement, while low-frequency scanning highlights contrast enhancement.
