Photothermal therapies use photosensitizing agents to convert applied light into heat, with the release of energy causing localized damage to targeted cells or other therapeutic effects.
Plasmonic nanoparticles are unique candidates for photosensitizing agents since the optical properties of the particles can be widely tuned by controlling particle size and shape, allowing formulations to be tailored to efficiently absorb light at specific wavelengths and convert the light into heat. Shining a laser into a solution of gold nanorods causes the solution temperature to rapidly increase, for example, as photons are absorbed by the nanorods and converted to heat that is transferred to the surrounding fluid.
For in vivo applications, near-infrared (NIR) light is often used for photothermal therapies – biological tissues are relatively transparent in portions of the NIR, allowing light to penetrate deeply without being absorbed and causing damage to the tissue. The optical properties of nanoparticles can be tuned to overlap with these biotransparent regions to absorb the applied NIR light. The figure below shows how the optical response of different types of nanoparticles can be tuned within the biotransparent window to absorb NIR light.
The heat generated by the photothermal effect is highly localized to the area around the nanoparticle, causing targeted damage to surrounding cells. The nanoparticle surfaces can be passivated with biologically inert poly(ethylene glycol) (PEG) or can be functionalized with antibodies or other targeting molecules to selectively bind to cells.
nanoComposix offers a comprehensive library of plasmonic nanoparticles that can be manufactured under ISO 13485:2016 and GMP/QSR quality conditions to produce biocompatible materials suitable for clinical trials and commercial use.
Summary of gold and silver nanoparticles available from nanoComposix and example application areas*
|Plasmon Peak Wavelength Range (nm)
|Topical/Injectable Photothermal Therapy
|Topical/Injectable Photothermal Therapy, Bioassays, Imaging, Drug and Gene Delivery
|Topical/Injectable Photothermal Therapy, Sensing, Drug and Gene Delivery
|Topical Photothermal Therapy, Molecular Detection
* Catalog nanoparticles from nanoComposix are intended for Research Use Only. For GMP or QSR compliant nanoparticle requirements, please contact us.
† hydrodynamic diameter measured by Dynamic Light Scattering (DLS)
‡ total diameter measured by Transmission Electron Microscopy (TEM)
Read below for guidelines on selecting a nanoparticle for your application and examples of nanoparticles used for photothermal therapies and nanoheating applications.
The selection of nanoparticle type and surface chemistry for photothermal applications depends on a variety of factors, such as whether the particles will be used for topical or injectable therapies, for nanoheating applications, or other in vitro uses. Other considerations include the formulation to be used for storage and delivery, the environment the particles will be exposed to during use, and the desired optical properties in combination with the illumination source.