Tissue-Mimicking Phantoms for Photothermal Performance Evaluations

Tissue-mimicking phantoms are objects that mimic various properties of real biological tissues. These properties can be optical, thermal, porosity, biological, etc., but the end application dictates the choice of phantoms with desired properties. For light-based therapies like plasmonic photothermal therapy (PPTT), phantoms mimicking the optical properties of real tissues are required to estimate the therapeutic dose of incident near-infrared (NIR) radiation (irradiation intensity or duration) which is affected by the light absorption or scattering by the biological tissue. Before conducting in vivo evaluations, the experiments are undertaken first on tissue-mimicking phantoms mimicking the optical properties of the same tumor. Such phantoms-based photothermal evaluations help in studying the photothermal performance of newly synthesized PPTT agent or its multifunctional nanocomposite in terms of the extent of thermal damage for a tumor size during PPTT with the considered therapeutic parameters of nanoparticles dose, irradiation intensity and duration. These phantom-based photothermal evaluations, in turn, assist in pre-treatment planning or optimization of these therapeutic parameters for further in vivo experiments. So, this chapter provides insights into tumor-tissue-mimicking phantoms suitable for PPTT or PPTT-assisted multimodal cancer therapy. The details pertaining to various constituents for preparation of the phantoms with desired optical properties and subsequent photothermal evaluations are described. Next, various steps for photothermal evaluations of nanoparticle-mediated PPTT within tumor-tissue phantoms are discussed, followed by a detailed discussion of different methods for temperature monitoring within phantoms during PPTT. Lastly, the photothermal performance evaluation of the synthesized multifunctional gold nanoblackbodies through the phantoms and the corresponding experimental setup used by the authors is discussed as a case study.