Multiphysics Modeling of Plasmonic Photothermal Heating Effects in Gold Nanoparticles and Nanoparticle Arrays

Abstract

Induced hyperthermia has been demonstrated as an effective oncological treatment due to the reduced heat tolerance of most malignant tissues; however, most techniques for heat generation within a target volume are insufficiently selective, inducing heating and unintended damage to surrounding healthy tissues. Plasmonic photothermal therapy (PPTT) utilizes light in the near-infrared (NIR) region to induce highly localized heating in gold nanoparticles, acting as exogenous chromophores, while minimizing heat generation in nearby tissues. However, optimization of treatment parameters requires extensive in vitro and in vivo studies for each new type of pathology and tissue targeted for treatment, a process that can be substantially reduced by implementing computational modeling. Herein, we describe the development of an innovative model based on the finite element method (FEM) that unites photothermal heating physics at the nanoscale with the micron scale to predict the heat generation of both single and arrays of gold nanoparticles. Plasmonic heating from laser illumination is computed for gold nanoparticles with three different morphologies: nanobipyramids, nanorods, and nanospheres. Model predictions based on laser illumination of nanorods at a visible wavelength (655 nm) are validated through experiments, which demonstrate a temperature increase of 5 °C in the viscinity of the nanorod array when illuminated by a 150 mW red laser. We also present a predictive model of the heating effect induced at 810 nm, wherein the heating efficiencies of the various morphologies sharing this excitation peak are compared. Our model shows that the nanorod is the most effective at heat generation in the isolated scenario, and arrays of 91 nm long nanorods reached hyperthermic levels (an increase of at least 5 °C) within a volume of over 20 μm 3 .

Photothermal inactivation of universal viral particles by localized surface plasmon resonance mediated heating filter membrane

“…The photothermal effect and temperature distributions were simulated using Ansys Fluent software (Ansys Inc., Pennsylvania, USA). Here, the material properties of Au NPs, such as the absorption cross-section and thermal conductivity, can be found in the literatures 52 – 54 . For the simulation of the photothermal effect and temperature distributions, we assumed that (1) The system was in a steady state; (2) The incident optical power of the light source was constant; and (3) There was no convective flow.…”

Investigation of the Plasmonic Interaction of Gold Nanoparticles Toward Plasmonic Photothermal Therapeutics

“…Computation of the overall optical absorption crosssection for the nanoparticle is required, considering the interparticle spacing and orientation of the nanoparticles in close proximity, for further estimation of the heat generation [4,9]. Such computation of the absorption crosssection provides assessment of photothermal conversion efficiency for clinical therapeutic applications [10].…”

“…In literature, the optical absorption cross-sections have been evaluated for a variety of nanoparticles by considering nanosphere dimers, and GNRs homodimer or heterodimer without much emphasis on the nanoparticle configurations (location and orientations within a tissue) [6][7][8][9]17]. In one of the study, the optical properties of only spherical heterodimer for interparticle spacings of 0.2 nm and 2 nm have been reported [18].…”

Assessment and Modeling of Plasmonic Photothermal Therapy Delivered via a Fiberoptic Microneedle Device Ex Vivo

“…What little work exists has explored ex vivo benchtop and early in vivo models, but demonstrated some promise that GNP photothermal heating can destroy malignant cells and inhibit tumor growth [19,23]. Gold nanorods (GNRs), among other GNP geometries, are increasingly utilized in PPTT due to their potential for high plasmonic heat generation [16,24] and optical dose tunability [25][26][27]. GNRs have been applied in numerous ex vivo and in vivo models of other varieties of cancer to explore the efficacy of PPTT [11,13].…”

“…A literature review revealed numerous finite element (FEM) analyses describing tissue photothermal heating by NIR light [36][37][38][39]. However, only a few reported the FEM model describing the porcine pancreas tissue-NIR light (1064 nm only) interaction [24,39]. However, these models utilized porcine liver tissue thermal and optical properties instead of pancreatic tissue due to a gap in the literature on this topic [39].…”