Effect of size, concentration, and type of spherical gold nanoparticles on heat evolution following laser irradiation using tissue-simulating phantoms

Photothermal therapy has recently gained a considerable attention particularly after the revolution of nanomaterials and nanotechnology. The aim of the present study is to assess the optimal photothermal response through investigating some effective parameters of spherical gold nanoparticles (AuNPs), e.g., type, size, and concentration, as a preclinical study for efficient photothermal treatment. Tissue-simulating phantoms based on agar and water media incorporated with two different types of AuNPs, spherical Au particles capped with citrate or spherical Au core–silica shell NPs, were built. Heat evolution for each NP type was recorded in the phantom matrix with different particle sizes at various concentrations following exposure to low laser power (irradiance 35 mW/cm²) and emitting at λ = 532 nm. Our results demonstrated that AuNPs capped with citrate recorded higher temperature elevations than those capped with silica shell. Particles with smaller sizes produced more heating effect than those having larger sizes. Also, higher temperatures were recorded at a critical concentration of NPs. Exponential decay constants based on theoretical calculations demonstrated that laser attenuation increases with the continuous increase of particle size and concentration.