Chen Zhimin, Fan Haihua, Li Jinxiang, Tie Shaolong, Lan Sheng
Opt Express. 2017 Jun 26;25(13):15093-15107. doi: 10.1364/OE.25.015093.
Gold nanorods (GNRs) are generally considered to be nontoxic to normal and cancer cells. They are usually accumulated at lysosomes after entering into cells, forming GNR clusters in which strong plasmonic coupling between GNRs is expected. We investigated the photothermal therapy of single cancer cells by exploiting the significantly enhanced two-photon-induced absorption of GNR clusters naturally created in the lysosomes of cancer cells. It was revealed numerically that the plasmonic coupling between GNRs in GNR clusters can effectively enhance the photothermal conversion efficiency. As a result, the thermal damage of single cancer cells can be induced by using pulse energy as low as ~70 pJ. In experiments, the locations of GNR clusters can be accurately determined through the detection of the two-photon-induced luminescence, which is also significantly enhanced, by using a confocal laser scanning microscope. The photothermal therapy was conducted by focusing femtosecond laser light on the targeted GNR clusters, generating bubbles and deforming cell membranes. The photothermal therapy proposed in this work can lead to the rapid and acute injury of single cancer cells. The dependence of the apoptosis time on the pulse energy of femtosecond laser light was also examined. Our findings suggest a novel strategy for the photothermal therapy of single cancer cells with ultralow energy.
金纳米棒（GNRs）通常被认为对正常细胞和癌细胞无毒。它们进入细胞后通常会在溶酶体中积累，形成GNR簇，预计其中GNR之间会有强烈的等离子体耦合。我们通过利用癌细胞溶酶体中自然形成的GNR簇显著增强的双光子诱导吸收来研究单个癌细胞的光热疗法。数值结果表明，GNR簇中GNR之间的等离子体耦合可以有效提高光热转换效率。因此，使用低至约70 pJ的脉冲能量就可以诱导单个癌细胞的热损伤。在实验中，通过使用共聚焦激光扫描显微镜检测同样显著增强的双光子诱导发光，可以准确确定GNR簇的位置。通过将飞秒激光聚焦在靶向的GNR簇上进行光热疗法，产生气泡并使细胞膜变形。这项工作中提出的光热疗法可导致单个癌细胞快速急性损伤。还研究了凋亡时间对飞秒激光脉冲能量的依赖性。我们的研究结果为超低能量的单个癌细胞光热疗法提出了一种新策略。
