Contemporary Polymer-Based Nanoparticle Systems for Photothermal Therapy

Abstract

Current approaches for the treatment of cancer, such as chemotherapy, radiotherapy, immunotherapy, and surgery, are limited by various factors, such as inadvertent necrosis of healthy cells, immunological destruction, or secondary cancer development. Hyperthermic therapy is a promising strategy intended to mitigate many of the shortcomings associated with traditional therapeutic approaches. However, to utilize this approach effectively, it must be targeted to specific tumor sites to prevent adverse side effects. In this regard, photothermal therapy, using intravenously-administered nanoparticle materials capable of eliciting hyperthermic effects in combination with the precise application of light in the near-infrared spectrum, has shown promise. Many different materials have been proposed, including various inorganic materials such as Au, Ag, and Germanium, and C-based materials. Unfortunately, these materials are limited by concerns about accumulation and potential cytotoxicity. Polymer-based nanoparticle systems have been investigated to overcome limitations associated with traditional inorganic nanoparticle systems. Some of the materials that have been investigated for this purpose include polypyrrole, poly-(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS), polydopamine, and polyaniline. The purpose of this review is to summarize these contemporary polymer-based nanoparticle technologies to acquire an understanding of their current applications and explore the potential for future improvements.

Keywords: photothermal therapy; polyaniline; polydopamine; polymeric nanoparticle; polypyrrole.

Figure 1

An example of polyaniline-based nanoparticles for photothermal therapy. (A) Photothermal images of a mouse after intratumoral injection of F127-modified polyaniline nanoparticles (F-PANPs) (1 mg/mL) with an 808 nm laser (0.5 W cm⁻², 3 min). When irradiated within the white circle area, the tumor (Point 1) and the surrounding tissue (Point 2) were heated. (B) Photothermal images of the tumor obtained at different time points. The scale bar indicates the temperature difference between 30 °C and 50 °C. (C) The relationship between sample temperature and laser illumination time is shown in (A). Reproduced from [24] with permission, copyright Elsevier, 2013.

Figure 2

A polypyrrole-based nanocomposite for near-infrared (NIR) photothermal therapy. NIR thermographic images (a) and temperature change (b) in tumor-bearing mice after intratumoral injection of PBS and chitosan-polypyrrole nanocomposites (CS-PPy NCs) and irradiation with an 808 nm laser (2.0 W cm⁻², 5 min). (c) The change in tumor size between Day 0 (before treatment) and 20 days after treatment. (d) Tumor volume growth curves for different groups of mice after different treatments. (e) The body weight after different treatments indicated over 20 days. The error bars indicate the mean ± standard deviation. Reproduced from [80] under open access license.

Figure 3

The NIR-II photothermal approach by a novel nanoagent. In vivo photothermal therapy of tumors. Mice were subjected to whole-body IR images after injection with a narrow band gap D–A conjugated polymer (TBDOPV–DT), with 2,2-bithiophene as the donor and thiophene-fused benzodifurandione-based oligo(p-phenylenevinylene) as the acceptor. (a) Intratumoral (0.56 mg kg⁻¹, 0.9 W cm⁻², and a 1064 nm laser) or (b) intravenous (1.94 mg kg⁻¹, 1.3 W cm⁻²) administration. (c) Growth rates of tumors after different treatments. (d) Representative size of the excised tumors. (e) Weight of tumor in each condition. (f) Changes in body weight of the mice with tumors. ** p ≤ 0.01; *** p ≤ 0.001. (g) H&E staining of tumor regions in different groups. Scale bars indicate 100 μm. Reproduced from [76] with permission, copyright American Chemical Society, 2018.