Standardized Measurements of the Light-To-Heat Output of Structurally-Complex Metallic Nanoparticles Used in Photothermal Therapies

Abstract

Photothermal therapy is a type of treatment method that uses the thermal properties of light to destroy tumors inside the body. It employs photothermal agents, such as nanoparticles that efficiently convert the incoming light into heat. When these nanoparticles are placed inside tumor cells, the heat generated changes the physiology and ultimately destroys the tumor cells. For this application, many different shapes, sizes and materials of nanoparticles are being explored by researchers. However, there are currently no standardized, easy-to-use methods for prescreening the heat output from generated by these nanoparticles before performing in-vivo and in-vitro tests. To solve this issue, we worked on developing a user-friendly pre-screening approach that can be used to measure the heat output generated by different nanoparticles prior to using animal models. Our system incurred several iterative changes in order to improve the reproducibility of heat measurements. We tested out our system using 2 types of gold nanoparticles: nanostars and nanoprisms. We performed different experiments to study the heating properties and morphological changes of these nanoparticles during the course of heating to understand their viability as photothermal agents. Both nanoparticles effectively converted light to heat but both sets of particles were susceptible to aggregation. We also measured the ability of each particle type to enhance the Raman spectra of two common thiol-containing Raman reporters; 4- mercaptobenzoic acid and benzene-1,4-dithiol whilst also converting light-to-heat.