Influence of Morphological Homogeneity of Superspherical Gold Nanoparticles on Plasmonic Photothermal Heat Generation

Abstract

The plasmonic photothermal (PPT) characteristics of gold nanostructures have been extensively investigated theoretically and experimentally due to their potential for use materials science and industry. The management of the size and shape of gold nanoparticles has been a key issue in the development of better solutions for PPT heat generation because their size and shape determine their resultant photothermal properties. However, the light absorption of gold nanostructures is mainly dependent on the wavelength and orientation of the incident light; hence, maintaining uniform size and shape is critical for achieving maximum photothermal energy. Morphologically homogeneous spherical gold nanoparticles, or super gold nanospheres prepared by slowly etching uniform octahedral gold nanoparticles, demonstrate better PPT heat generation compared with commercially available nonsmooth gold nanoparticles (GNSs). The PPT heating experiments show a maximum temperature difference of 5.7 °C between the super and ordinary GNSs with the same average maximum Feret's diameters, which result from the more efficient PPT heat power generation (20.6%) of the super GNSs. In an electromagnetic‐wave simulation, the super GNSs show lower polarization dependence and a 24.6% higher absorption cross‐section than ordinary GNSs.

Probing Inherent Optical Anisotropy in Substrates via Direct Nanoimaging of Mie Scattering

“…Forward scattering in Mie scattering occurs very strongly, whereas backward scattering is relatively weak and the near electromagnetic field distribution is strongly dependent to the size of the particle with respect to the wavelength. Additionally, Mie scattering is influenced by the shape of the particles, with nonspherical or heterogeneous particles exhibiting complex variations in scattering intensity and direction. , Since Mie scattering is exceedingly sensitive to geometric factors, the environmental substrate may break the symmetry of the scattering pattern, especially in the case of the inherently anisotropic substrate. To exploit these phenomena, we conducted direct optical imaging of Mie scattering in various configurations with different substrates and incident wavevectors, as illustrated in Figure b.…”

“…These satellite peaks exhibit a symmetric distribution, which can be attributed to the superspherical shape of the s-AuNPs (Figure S5). , To further investigate the nature of the satellite peaks, we conducted FDTD simulations. These simulations aimed to explore the origin and characteristics of these satellite peaks by utilizing the ε xx (real part of the dielectric function for x -direction) and ε yy (real part of the dielectric function for y -direction) components of the dielectric function of the substrate.…”

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

“…the oscillating surface electrons which transfer their kinetic energy into the nanoparticle lattice through electron-phonon interaction. [12][13][14][15] It results that heat dissipates through nanoparticle-medium interface leading to a significant temperature rise in the surrounding medium. The temperature elevation rate in this case is highly dependent on the gold nanoparticles optical cross section which depends on their shape, size, and the light wavelength.…”

Gold Nanobipyramid-Based Photothermal Sensors for the Portable Evaluation of Total Antioxidant Capacity

“…First, the synthesis of uniform AuNBPs is straightforward and reliable . Their uniform size and morphological homogeneity provide narrower absorption peaks, rendering AuNBPs as being particularly effective for absorbing light at specific wavelengths and achieving higher photothermal conversion . Second, antioxidant-induced silver deposition on AuNBP surfaces enabled the LSPR and photothermal effect to be fine-tuned without introducing any background interference. ,,, Finally, the well-defined optical properties and high RIS render AuNBPs as being ideally suited for highly sensitive photothermal assays because even low analyte concentrations could substantially change the photothermal conversion efficiency and resultant temperatures.…”