Abstract

Background

Photothermal therapy is currently under the spotlight to improve the efficacy of minimally invasive thermal treatment of solid tumors. The interplay of several factors including the radiation wavelengths and the nanoparticle characteristics underlie the thermal outcome. However, a quantitative thermal analysis in in vivo models embedding nanoparticles and under different near-infrared (NIR) wavelengths is missing.

Purpose

We evaluate the thermal effects induced by different combinations of NIR laser wavelengths and gold nanorods (GNRs) in breast cancer tumor models in mice.

Materials and methods

Four laser wavelengths within the therapeutic window, i.e., 808, 940, 975, and 1064 nm were employed, and corresponding GNRs were intratumorally injected. The tissue thermal response was evaluated in terms of temperature profile and time constants, considering the step response of a first-order system as a model.

Results

The 808 nm and 1064 nm lasers experienced the highest temperature enhancements (>24%) in presence of GNRs compared to controls; conversely, 975 nm and 940 nm lasers showed high temperatures in controls due to significant tissue absorption and the lowest temperature difference with and without GNRs (temperature enhancement <10%). The presence of GNRs resulted in small time constants, thus quicker laser-induced thermal response (from 67 s to 33 s at 808 nm).

Conclusions

The thermal responses of different GNR-laser wavelength combinations quantitatively validate the widespread usage of 808 nm laser for nanoparticle-assisted photothermal procedures. Moreover, our results provide insights on other usable wavelengths, toward the identification of an effective photothermal treatment strategy for the removal of focal malignancies.

中文翻译：

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乳腺癌模型中 808 nm、940 nm、975 nm 和 1064 nm 波长的激光照射-金纳米棒组合的热分析

摘要

背景

光热疗法目前备受关注，以提高实体瘤微创热疗的疗效。包括辐射波长和纳米颗粒特性在内的几个因素的相互作用是热结果的基础。然而，在嵌入纳米粒子和不同近红外 (NIR) 波长下的体内模型中缺少定量热分析。

目的

我们评估了近红外激光波长和金纳米棒 (GNR) 的不同组合在小鼠乳腺癌肿瘤模型中引起的热效应。

材料和方法

在治疗窗内使用四种激光波长，即808、940、975和1064 nm，并在瘤内注射相应的GNR。将一阶系统的阶跃响应作为模型，根据温度分布和时间常数评估组织热响应。

结果

与对照组相比，808 nm 和 1064 nm 激光器在 GNR 存在下经历了最高的温度增强 (>24%)；相反，975 nm 和 940 nm 激光在对照中显示出高温，这是由于显着的组织吸收以及有和没有 GNR 的最低温差（温度增强 <10%）。GNR 的存在导致较小的时间常数，因此激光诱导的热响应更快（从 67 秒到 33 秒，在 808 nm）。

结论

不同 GNR 激光波长组合的热响应定量验证了 808 nm 激光在纳米粒子辅助光热程序中的广泛使用。此外，我们的结果提供了对其他可用波长的见解，有助于确定有效的光热治疗策略，以去除局灶性恶性肿瘤。