Effect of gold nanoparticles in the local heating of skin tumors induced by phototherapy

Abstract

During optical therapies, several types of interaction between the optical radiation and the target tissue can occur. The application of different power densities and the variation of the exposure time can cause from photochemical reactions to photodisruption. Photothermal therapy (PTT) is based in the thermal interactions, where the biological injury is provoked by a given increase of their temperature during the exposition to the optical source. Another treatment option very extended in several clinical fields due to its promising results is Photodynamic Therapy. This treatment modality is based in photochemical reactions where it is also required oxygen and the administration of a photosensitive substance known as photosensitizer. The use of nanotechnology in optical therapeutic techniques, constitutes a novel promising treatment strategy. Specifically, gold nanoparticles can improve different issues related to the transport of photosensitizers or the light energy absorption and the subsequent heat generation. This work focuses in the effects that can produce the use of gold nanoparticles in Photothermal and Photodynamic Therapies applied to skin diseases commonly treated by means of these techniques. We present a thermal model that permits to calculate the temperature distribution in different kinds of pathological dermatological tissues depending on the optical power provided by the optical source. The results obtained permit to compare the thermal injury produced depending on not only the provided power but also the type of pathology and the incorporation or not of gold nanoparticles in the target tissue.