Numerical Study of Optical and Photothermal Properties of SiO ₂ @Ag <i> _x </i> Au _1– <i> _x </i> Core–Shell Nanoparticles for Prostate Cancer

ABSTRACT Targeted photothermal therapy (PTT) using plasmonic nanoparticles represents a promising minimally invasive approach for prostate cancer (PrC) treatment. A finite element method (FEM) framework was first validated by reproducing the surface plasmon resonance (SPR) peak positions of alloy nanospheres in water (WM), with compositions ranging from x = 1 (Ag) to x = 1 (Au), showing excellent agreement with experimental data. Based on this validation, the alloy was selected as an optimal composition and incorporated as the shell material in core@shell nanoparticles (CSNPs) to evaluate its optical and thermoplasmonic properties in WM, human prostate tissue (HPT), and tumorous prostate tissue (TPT). The geometric ratio was systematically varied to optimize resonance within the near‐infrared (NIR) therapeutic window to analyze plasmonic heating and identify a suitable configuration for PrC PTT. The configuration emerged as optimal for all studied biological media, shifting the SPR peak position and maximizing Joule heating efficiency, with and specifically in HPT. A pronounced regime‐dependent thermal response was observed: under continuous‐wave (CW) irradiation at , TPT reached the highest steady‐state temperature ( due to its lower thermal conductivity. This temperature lies within the moderate hyperthermia range (42°C‒45°C) and considered favorable for PTT applications. In contrast, femtosecond (fs)‐pulsed irradiation at produced a transient temperature rise of ( in TPT at the initial instant , driven purely by optical absorption sensitivity. These findings highlight a dual‐regime behavior: CW irradiation enables controlled mild hyperthermia, while fs‐pulsed irradiation leads to enhanced localized heating effects, depending on the desired therapeutic regime. The spectral shift between HPT and TPT further ensures selectivity, providing a versatile platform for high‐precision, selective PTT of PrC.