Photothermal effects in small gold nanorod aggregates for therapeutic applications

TL;DR

This study investigates how small gold nanorod aggregates exhibit enhanced photothermal effects due to plasmonic coupling, with implications for optimizing therapeutic applications by understanding their optical behavior and temperature rise.

Contribution

It provides a numerical analysis of photothermal effects in ordered and random gold nanorod aggregates, highlighting how aggregation influences plasmonic resonance and heating for therapy.

Findings

Aggregates show higher absorption and temperature rise than single nanorods.

Ordered aggregates cause blueshifts, while random aggregates cause redshifts in resonance.

Resonance peaks can be tailored for biological therapeutic windows.

Abstract

Proximity of the metal nanoparticles enhance the plasmonic coupling and shifts the resonance. This article presents a numerical study of the photothermal effect in aggregates of small gold nanorods considering the ordered as well as random aggregates. In the ordered aggregates, there is lateral coupling which causes blueshifts in the plasmonic resonance, while in the random aggregates there are redshifts in the plasmonic resonance. The plasmon response of latter could be tailored up to the second infrared biological therapeutic window. It has been observed that the aggregates show higher absorption power and therefore, higher temperature rise compared to the single gold nanorod or monodispersive nanorods. The absorption resonance peak position of the random aggregate depends on the incident and polarization angles of the incident light. The aggregation of the nanoparticles often inherently occurs in the biological medium which affects the photothermal process. This study helps to understand the photothermal heating of nanoparticle aggregates and the use of the optimal light source concerning the absorption peak of the aggregates suspension for therapeutic uses.