Physical aspects of gold nanoparticles as cancer killer therapy

The objective of this research is to increase the diagnostics and the radiotherapy efficiency enhancing the effective atomic number of cancer tissues using the injection of gold nanoparticles. The proposed method employs spheroidal gold nanoparticles, with an average diameter of about 10 nm, prepared using Nd:YAG laser ablation in water. Their distribution in tumor tissues can be obtained by local injection, by transport through the blood flux or by using functionalized nanoparticles transported in specific organs. The characterization of the nanoparticles was made by electron microscopy, characteristic X-ray fluorescence and optical absorbance investigation in the UV-visible region. The calculations demonstrate that the mass attenuation coefficients for X-rays and the proton stopping power in the tissue with nanoparticles increase significantly using a 0.1% concentration in weight. In conclusion, the presence of gold nanoparticles in the cancer tissues enhances significantly the cross section of the photoelectric effect for X-ray absorption and the stopping power of incident energetic protons, allowing the higher dose release. The releasing of nanoparticles only in the tumor site and not in the healthy tissues remains the most important problem to be resolved. The advances of this research concern, mostly, on acquisition of knowledge about the employment of nanoparticles locally injected in tumor site, to significantly enhance the contrast image and the dose released during radiotherapy with X-rays and proton beams.