Heat Generation in Irradiated Gold Nanoparticle Solutions for Hyperthermia Applications

Xi Gu,Victoria Timchenko,Robert A Taylor,Darson D Li,Guan H Yeoh

doi:10.3390/pr9020368

Xi Gu, Victoria Timchenko + Show 3 more

Open Access

https://doi.org/10.3390/pr9020368

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Abstract

Gold nanoparticles (GNP) aided hyperthermia has demonstrated promising results in the treatment of cancer. However, most existing investigations focus only on the extinction spectra of GNP solutions, few reported the actual heat generation capability of these solutions to estimate their real potential in in-situ hyperthermia treatment. In this study, the impact of GNP clustering on the optical properties and heating capability of GNP aggregates in acidic solutions have been investigated. It was found that localized heat generation could be significantly enhanced (to up to 60.0 °C) when acidic solutions were illuminated by a near infrared light source at 1.7 W/cm2. In addition, infrared thermography imaging can only detect the surface temperature during thermal treatment, leaving the localized temperature distribution inside the tissues unknown. To overcome this limitation, in this study, the absorbed energy during NIR irradiation in GNP solutions was obtained computationally by coupling the P1 approximation with the DDA calculation to predict the localized temperature change in the solutions. It was demonstrated that due to the accumulation and dissipation of heat, some local areas showed higher temperature increase with the hot spots being connected and merged over time.

Highlights

The usage of heat as a method of treating diseases has been known in different cultures since ancient times
Apart from the overall trend, the configuration of Gold nanoparticles (GNP) cluster in Figure 7a is very similar to the structure Octamer 8-1 predicted by Li et al.’s simulation [9] in a solution of pH = 3.5
A few typical structures of GNP aggregates were chosen from Li et al.’s predictions [9] to calculate the optical properties of suspended GNP in acidic solution for further investigations

Summary

Introduction

The usage of heat as a method of treating diseases has been known in different cultures since ancient times. By using mild hyperthermia therapy, tissues are heated to a temperature within the range 39–45 ◦ C [1]. At this temperature, properties of specific tumor tissues can be gradually altered because they have a lower heat tolerance than normal cells [2]. The normal cells, with a rather high heat tolerance, can survive under this temperature range. While thermotherapy has shown promising clinical results, it is often difficult to control the heat generation and temperature distribution in tumors and not to overheat surrounding healthy tissues. Gold nanoparticles (GNPs) have shown unique promise in hyperthermia treatments because of their biocompatibility and strong optical resonant absorption of near infrared (NIR) light in the so-called optical therapeutic window [2,3,4]

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