A note on laser penetration in nanoshell deposited tissue

The radiative intensity profiles of biological tissues infused with gold nanoshells and illuminated with collimated radiation are compared. A one-dimensional radiative transport model using the P, approximation is used to calculate the collimated and diffuse components of incident radiation in a series of semi-infinite slabs representing nine distinct human tissue media. Each tissue model is subject to 633-nm collimated radiation on one end under four concentrations of nanoshell embedment, with theoretical nanoshells tuned to reach peak absorption at 630 nm. The penetration depth each component is shown to be highly influenced by the base tissue extinction, and the profile morphology can be visibly categorized into one of two groups: low scattering, with scattering coefficients between 4000 and 8000 m(-1), and high scattering, with scattering coefficients in the range of 30,000 and 40,000 m(-1). Increasing nanoshell density up to 7 x 10(16) m(-3) for both types is shown to decrease penetration depth and lower radiative intensity for the diffuse component while not affecting the penetration depth or intensity of the collimated component. (C) 2009 Elsevier Ltd. All rights reserved.