Best-Practice Guidelines for Reporting the Photothermal Effects of Plasmonic Nanoheaters.

Abstract

Photothermal therapy (PTT) is an emerging class of preclinical cancer treatments that allows the localized thermal ablation of tumors, generally using light sources in the near-infrared (NIR) to maximize tissue penetration and minimize healthy cell damage. Although PTT can be achieved with other materials featuring a high absorption cross-section at the NIR wavelength of the incident light source, plasmonic nanoparticles (NPs) have emerged as effective tools thanks to their high extinction cross-section, photothermal conversion efficiency, and tunable optical properties. Numerous studies have described the use of plasmonic NPs as nanoheaters both <i>in vitro</i> and <i>in vivo</i>. However, these reports often lack critical methodological details regarding the evaluation of photothermal effects. Key experimental parameters ─ such as laser type, beam profile, calibration procedures, and the use of optical elements (<i>e.g</i>., collimators, filters) ─ are often not specified, despite their substantial impact on the reported thermal outcomes. This lack of transparency hampers reproducibility and complicates cross-study comparisons. We analyze hereby a set of experimental design parameters that are essential for the accurate assessment of PTT performance, with a particular focus on plasmonic NPs as photothermal agents. This work is supported by experimental data obtained using gold nanostars under various irradiation scenarios. We conclude with a practical checkpoint guide of factors to be considered when conducting PTT experiments.