Simulating the optical properties of graphene nanodisks for photothermal therapy

Abstract

Photothermal therapy, the process of converting light from a laser into heat strong enough to destroy cancer cells, has risen as a promising, safe and minimally invasive means for the treatment of cancer. Designing nanoparticles that can efficiently absorb light and convert it to heat is of critical importance for photothermal therapy. In the recent years, graphene has emerged as a tunable, versatile and promising material in a wide range of applications. There is a lack of studies on graphene based nanoparticles for photothermal therapy. This work presents the use of the finite elements method to calculate the absorption efficiency spectra of single and multiple layer graphene nanodisks of different sizes for the first time. For a graphene sheet, the electromagnetic properties were described in terms of the surface conductivity by Kubo model of conductivity. The results show that increasing the number of graphene layers or radii of nanodisks, increases the absorption efficiency. It was also noticed that the shapes of the absorption spectra of the graphene nanodisks do not have resonance peaks like those of the gold nanoparticles and instead have a more constant response. Despite the fact that the graphene nanodisks demonstrated possess much weaker absorption in comparison to gold nanoparticles, it is expected that increasing the number of layers further would increase the absorption efficiency till it becomes comparable to or maybe even better than gold nanoparticles. The results show the feasibility of graphene based nanoparticles for photothermal therapy and encourage more research on the topic.