Boutopoulos Christos, Hatef Ali, Fortin-Deschênes Matthieu, Meunier Michel
Laser Processing and Plasmonics Laboratory, Engineering Physics Department, Polytechnique Montréal, Montréal, Québec H3C 3A7, Canada.
Nanoscale. 2015 Jul 21;7(27):11758-65. doi: 10.1039/c5nr02721g. Epub 2015 Jun 24.
Plasmonic nanoparticles can lead to extreme confinement of the light in the near field. This unique ability of plasmonic nanoparticles can be used to generate nanobubbles in liquid. In this work, we demonstrate with single-particle monitoring that 100 nm gold nanoparticles (AuNPs) irradiated by off-resonance femtosecond (fs) laser in the tissue therapeutic optical window (λ = 800 nm), can act as a durable nanolenses in liquid and provoke nanocavitation while remaining intact. We have employed combined ultrafast shadowgraphic imaging, in situ dark field imaging and dynamic tracking of AuNP Brownian motion to ensure the study of individual AuNPs/nanolenses under multiple fs laser pulses. We demonstrate that 100 nm AuNPs can generate multiple, highly confined (radius down to 550 nm) and transient (life time < 50 ns) nanobubbles. The latter is of significant importance for future development of in vivo AuNP-assisted laser nanosurgery and theranostic applications, where AuNP fragmentation should be avoided to prevent side effects, such as cytotoxicity and immune system's response. The experimental results have been correlated with theoretical modeling to provide an insight to the AuNP-safe cavitation mechanism as well as to investigate the deformation mechanism of the AuNPs at high laser fluences.
等离子体纳米颗粒可导致光在近场中的极端限制。等离子体纳米颗粒的这种独特能力可用于在液体中产生纳米气泡。在这项工作中，我们通过单粒子监测证明，在组织治疗光学窗口（λ = 800 nm）中用非共振飞秒（fs）激光照射的100 nm金纳米颗粒（AuNP），在液体中可作为持久的纳米透镜并引发纳米空化，同时保持完整。我们采用了超快阴影成像、原位暗场成像和AuNP布朗运动的动态跟踪相结合的方法，以确保在多个飞秒激光脉冲下对单个AuNP/纳米透镜进行研究。我们证明100 nm的AuNP可以产生多个高度受限（半径低至550 nm）且瞬态（寿命<50 ns）的纳米气泡。后者对于体内AuNP辅助激光纳米手术和治疗诊断应用的未来发展具有重要意义，在这些应用中应避免AuNP破碎以防止副作用，如细胞毒性和免疫系统反应。实验结果已与理论模型相关联，以深入了解AuNP安全空化机制，并研究高激光能量密度下AuNP的变形机制。
