Gold nanoshell photomodification under a single-nanosecond laser pulse accompanied by color-shifting and bubble formation phenomena
Gold nanoshell photomodification under a single-nanosecond laser pulse accompanied by color-shifting and bubble formation phenomena
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DOI：
10.1088/0957-4484/19/01/015701
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发表时间：
2008-01-09
期刊：
影响因子：
3.5
通讯作者：
Khlebtsov, Nikolai
中科院分区：
文献类型：
--
作者：
Akchurin, Garif;Khlebtsov, Boris;Khlebtsov, Nikolai
激光-纳米粒子相互作用对于激光和纳米技术在治疗癌症或病原微生物方面的生物医学应用至关重要。我们报告了在1纳秒脉冲后首次观察到的金纳米壳溶液的激光诱导着色，以及在约4 mJ cm（-2）的激光能量密度下前所未有的低气泡形成（作为癌细胞杀伤的主要机制）阈值，这对正常组织是安全的。具体地，用单个4 ns（1064 nm）或8 ns（900 nm）激光脉冲以0.1mJ cm（-2）至50 J cm（-2）的能量密度照射二氧化硅/金纳米壳（140/15 nm）悬浮液。通过肉眼观察到溶液红色着色，这通过吸收光谱最大值从纳米壳的初始900 nm蓝移到常规胶体金纳米球的530 nm来证实。TEM图像揭示了纳米颗粒的显著光改性，包括金壳的完全碎裂、二氧化硅核结构的变化、小的20-30 nm孤立球形金纳米颗粒、具有中心孔的金纳米壳以及附着于二氧化硅核的大的和小的球形金颗粒的形成。用光热（PT）热透镜技术对气泡形成现象的时间分辨监测表明，在施加能量密度为5-10 mJ cm（-2）或更高的单个8 ns脉冲后，下一个脉冲不产生任何PT响应，表明由于金壳改性，吸收急剧下降。我们还观察到气泡膨胀时间对激光能量的依赖性，PT信号异常快速上升（类似于0.2 J cm（-2）时的3.5 ns标度）。所观察到的现象在医学应用中的应用进行了讨论，包括一个简单的激光纳米粒子相互作用的视觉颜色测试。
Laser-nanoparticle interaction is crucial for biomedical applications of lasers and nanotechnology to the treatment of cancer or pathogenic microorganisms. We report on the first observation of laser-induced coloring of gold nanoshell solution after a one nanosecond pulse and an unprecedentedly low bubble formation (as the main mechanism of cancer cell killing) threshold at a laser fluence of about 4 mJ cm(-2), which is safe for normal tissue. Specifically, silica/gold nanoshell (140/15 nm) suspensions were irradiated with a single 4 ns (1064 nm) or 8 ns (900 nm) laser pulse at fluences ranging from 0.1 mJ cm(-2) to 50 J cm(-2). Solution red coloring was observed by the naked eye confirmed by blue-shifting of the absorption spectrum maximum from the initial 900 nm for nanoshells to 530 nm for conventional colloidal gold nanospheres. TEM images revealed significant photomodification of nanoparticles including complete fragmentation of gold shells, changes in silica core structure, formation of small 20-30 nm isolated spherical gold nanoparticles, gold nanoshells with central holes, and large and small spherical gold particles attached to a silica core. The time-resolved monitoring of bubble formation phenomena with the photothermal (PT) thermolens technique demonstrated that after application of a single 8 ns pulse at fluences 5-10 mJ cm(-2) and higher the next pulse did not produce any PT response, indicating a dramatic decrease in absorption because of gold shell modification. We also observed a dependence of the bubble expansion time on the laser energy with unusually very fast PT signal rising (similar to 3.5 ns scale at 0.2 J cm(-2)). Application of the observed phenomena to medical applications is discussed, including a simple visual color test for laser-nanoparticle interaction.