Photothermal Properties of Size-tunable Gold Nanotriangles with Comparable Plasmon Resonances

Abstract

In this work, we compare the heating efficiency across varying concentrations of two gold nanotriangle (AuNT) samples of different sizes but with similar plasmon resonance, prepared from the same synthesis batch. Finite-difference time-domain (FDTD) simulations were conducted to evaluate single-particle predictors, including the Joule number (Jo), absorption cross section (σAbs), and theoretical extinction efficiency (QExt). These theoretical parameters were contrasted with experimental measurements obtained from the heating curves of AuNT dispersions irradiated with an 808 nm continuous-wave laser. From these experiments, specific loss power (SLP) values and experimental photothermal efficiency were determined (). Our findings reveal that experimental measurements, unlike single-nanoparticle predictions, account for collective effects such as multiple scattering, which partially offsets the reduction in heating efficiency caused by laser attenuation at higher concentrations. The heating performance of AuNTs normalized by Au mass showed significant differences in favour of smaller AuNTs at concentrations below 100 µM. On the contrary, the heating performance per NP resulted higher for larger AuNTs at concentrations above 100 µM. This behavior highlights the importance of performing accurate analysis in order to design nanoparticles that optimize photothermal efficiency according to the application. Overall, this study demonstrates that combining theoretical and experimental analyses provides valuable insights into the design and optimization of plasmonic nanomaterials for applications in photothermal therapy and plasmonic-driven chemical reactions.