Space simulations of thermal fields generated in bone tissue for application to nanophotohyperthermia and nanophotothermolysis

Abstract

The use of nanoparticles in medical applications has been gaining momentum as antibody-conjugated nanoparticles are becoming more and more feasible as a means of targeted delivery of various therapies. Irradiating nanoparticles with light of strongly-absorbed wavelengths allows them to act as heat generation sites. Two therapies utilize these nanoparticle heat sources to kill the target cells: nanophotohyperthermia, which heats the particles just enough to disrupt cell function and trigger cell death; and nanophotothermolysis, which heats the particles to such extremes as to destroy the cell membrane. The use of optical wavelengths in the range of 750-1100 nm has been to capitalize on the "optical transparency window" of biotissues between the absorption peaks of hemoglobin in the visible end and water in the near-IR. However, further research has shown that a plasmon resonance can greatly affect the absorption characteristics of nanoparticles at the plasmon resonant frequency, allowing for increased absorption characteristics at desirable wavelengths. Thus, other transparency windows may find use in a similar manner, such as nanoparticle heating by RF waves. This paper presents the modeling of 3D thermal fields around nanoparticle absorbers in bone tissue for various frequencies. A comparison of the heating effectiveness across multiple wavelengths is discussed for application to nanophotothermolysis and nanophotohyperthermia treatments in or near biological hard tissue.