Study of the Optical Properties of Functionalized Gold Nanoparticles in Different Tissues and Their Correlation with the Temperature Increase

Abstract

Mie theory explains the interaction of light with a gold nanoparticle (AuNP) through the absorption (𝐶abs), scattering (𝐶sca), and extinction (𝐶ext) cross sections. These parameters have been calculated in the case of AuNPs dispersed in homogeneous media, but not for specific tissues. The aim of this research was to theoretically obtain the optical cross sections (𝐶abs, 𝐶sca, and 𝐶ext) of functionalized AuNPs in liver and colon tissues through Mie theory and correlate them with the temperature increase observed experimentally in tissues containing AuNPs under plasmonic photothermal irradiation using a Nd-YAG laser (𝜆 = 532 nm). Calculations showed that 𝐶abs represents 98.96 ± 0.03% of 𝐶ext at 532 nm. The 𝐶ext value for a functionalized AuNP in water was 365.66 nm2 (94% of the theoretical maximum value at 522.5 nm), 404.24 nm2 in colon (98% of the theoretical maximum value at 525 nm), and 442.39nm2 in liver (96% of the theoretical maximum value at 525 nm). Therefore, nanoparticles irradiated at 532nm are very close to their resonance value.These results correlated with the experimental irradiation of functionalized AuNPs in different tissues, where the average temperature increase showed the pattern liver > colon > water. The temperature increase observed (Δ𝑇 up to 13∘C) is sufficient to produce cellular death.