July 30 2017 by Juili Kelvekar
At the nanoscale some materials exhibit extraordinary properties. Arguably, the most widely utilized inorganic nanomaterial is gold. When gold nanoparticles (AuNPs) are irradiated with certain wavelengths of light they form dipole oscillation that results in Surface Plasmon Resonance (SPR). Essentially, light causes a vibration in the electron cloud, resonating at a particular set of frequencies. Due to this property, AuNPs have increasingly found utility in novel medical applications and research.
Here 4 emerging medical uses of plasmonic gold nanoparticles are examined.
Examples of AuNPs as exogenous contrast for photoacoustic imaging:
Examples of Photodynamic Therapy using AuNPs:
3. Photothermal Therapy: The released thermal energy from light irradiation of AuNPs is shown to help kill targeted cells. Gold nanoparticles are targeted to a tissue of interest and then are illuminated with a light source, generally a monochromatic light source with a peak wavelength corresponding to the SPR of the gold nanoparticle. The gold nanoparticles absorbs light and releases heat. Since AuNPs are better light absorbers than tissue, when localized to a specific tissue, such as a cancerous tumor, gold nanoparticles can successfully kill the diseased cells via hyperthermia while sparing the surrounding healthy tissues.
Examples of Photothermal Therapy using AuNPs:
4. Radiation Therapy: In radiation therapy, high energy ionizing radiation is used to shrink tumors and kill cancer cells. Disadvantages of single agent radiation therapy include injuring surrounding healthy tissue, only low intensities reach tumors that are deep inside the body, and cells can develop resistance to radiation. These disadvantages can be overcome by using gold nanoparticles as a radiation sensitizer. AuNPs are biocompatible and can be delivered efficiently to the diseased site to enhance the effect of radiation. Additionally, the size and shape of the AuNPs can be tuned for therapeutic delivery requirements and to achieve optimum effect.17, 18 Overall, by introducing gold nanoparticles, the radiation dose can be significantly reduced while maintaining cancer-localized therapeutic benefit.
THE GOLDEN VALUE OF AuNPs
AuNPs are favored for theranostics (therapy + diagnostics) over other plasmonic nanoparticles because they maintain biological compatibility, can be synthesized easily, can be produced in different shapes and sizes depending upon application, and can be targeted to a wide variety of pathologies in the human body.
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