Size, Shape, and Wavelength Effect on Photothermal Heat Elevation of Gold Nanoparticles: Absorption Coefficient Experimental Measurement

Abstract

Complex‐shaped nanoparticles as gold nanourchins (GNU) and nanorods (GNR) are very suitable agents in the case of photothermal therapy due to their photon‐heat conversion ability in the red and near‐infrared region (NIR). The quantification in heat generation of complex shaped nanostructures is an important key to predict the therapeutic effect of these nanoparticles. For that, the determination of the nanoparticles absorption cross section (σAbs) responsible for the heat generation is one of the important steps before any application. Although it is obvious to determine σAbs for spheres via Mie's theory, in the case of complex structures like GNU or GNR, this parameter is difficult to model. In this work, a new methodology is used to determine experimentally σAbs for both GNU and GNR. Experimental measurements of the photothermal properties of 100 nm size GNU and two different sizes of GNRs are studied regarding different parameters such as concentration, laser excitation wavelength, and exposure time. By using the heat transfer theory, the temperature elevation in the nanoparticles solutions is converted to temperature elevation at the nanoparticles surface and σAbs values are then calculated for both GNU and GNR in the NIR spectral region.

Multimodal bioimaging using nanodiamond and gold hybrid nanoparticles

“…Such particles are quite biocompatible and safe at least in the absence of laser irradiation of specially selected wavelength, power, time exposure. Large spherical gold NP penetrate the cells via endocytosis and phagocytosis and are localized in endosomes in the cytoplasm on the cell periphery 14 , 16 , 52 – 54 . Thus, for the ND@Au particles used in this study we can suggest that they penetrate in cells, localize in endosomes in cytoplasm and create no damage or less damage than smaller particles can do, which directly interact with membrane and affect its structure 51 – 54 .…”

“…Large spherical gold NP penetrate the cells via endocytosis and phagocytosis and are localized in endosomes in the cytoplasm on the cell periphery 14 , 16 , 52 – 54 . Thus, for the ND@Au particles used in this study we can suggest that they penetrate in cells, localize in endosomes in cytoplasm and create no damage or less damage than smaller particles can do, which directly interact with membrane and affect its structure 51 – 54 . All together allows us to conclude that ND@Au can be considered as a safe cellular marker.…”

“…Another potential advantage is multifunctional (theranostic) applications, as the combination of nanogold and laser treatments is used for development of methods photothermal and photodynamic therapy. Optical and plasmonic properties of nanogold, being important both for bioimaging/biosensing and for photo treatment, highly depend on the NP geometry 54 . Thus, surface plasmon resonance of gold nanoshells in the core–shell Au–Si structure with core size about 100 nm was shown to be controlled by varying the shell thickness.…”

DOTAREM (DOTA)–Gold-Nanoparticles: Design, Spectroscopic Evaluation to Build Hybrid Contrast Agents to Applications in Nanomedecine

“…The PTT set up was already described by the authors. [30][31][32] The solutions volume (1 mL) and the irradiation surface (1 cm 2 ) were maintained at a constant during all the measurements.…”

Dynamic change in optical properties of a nanoparticle embedded tumor phantom for plasmonic photothermal cancer therapeutics

“…Gold nanorods (GNRs) are widely used for plasmonic photothermal cancer therapy, due to their significant near-infrared (NIR) radiation absorption within therapeutic optical window-I from 700 to 900 nm [7][8][9][10]. The optical characteristics such as absorption and scattering coefficients of tumors are altered due to the incorporation of nanoparticles such as GNRs [11][12][13]. These optical properties are further influenced by increase in temperature of the tumor during photothermal interaction [14][15][16][17].…”