Posted: November 13, 2006

Improving nanoscale heat therapy for cancer

(Nanowerk News) Gold nanoparticles, through their unique ability to convert light into heat, show great promise as miniature heaters capable of cooking cancer cells to death (click here for earlier stories). Now, that work gets a theory boost thanks to the efforts of Nikolai Khlebtsov, Ph.D., and colleagues at the Russian Academy of Sciences, who have developed a theory to explain the relationship between nanoparticle size, shape, and other physical parameters and the efficiency with which they absorb light, the most important factor in determining how much heat a given type of gold nanoparticle will produce to kill cancer cells.
Reporting its work in the journal Nanotechnology ("Optical amplification of photothermal therapy with gold nanoparticles and nanoclusters"), Khlebtsov’s group developed a theoretical approach that could model the light-absorbing behavior of single nanoparticles, including rods, spheres, or silicon/gold nanoshells; chains of gold nanoparticles; and three-dimensional clusters, both bare and coated with biopolymers. The researchers focused on light with a wavelength of 520 nanometers, corresponding to the wavelength that best passes through tissue unabsorbed. As a means of checking the validity of their theoretical model and computer simulations, the group predicted the optical properties of gold spheres as a function of size. The results of those predictions matched the known optical properties of gold nanoparticles.
The researchers’ work predicts that gold nanoshells with silica cores of 50 to 100 nanometers in diameter and gold shells of 3 to 8 nanometers in thickness would be more efficient light capture agents than single spherical gold nanoparticles. This work also suggests that gold nanorods that are 15 to 20 nanometers across and 50 to 70 nanometers long would also be highly efficient photothermal therapy agents. The researchers confirmed these predictions with experimental data.
Source: National Cancer Institute
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