IMEC, Bio-Nano Electronics, Functional Nanosystems, Kapeldreef 75, 3001 Leuven, Belgium; Department of Chemistry, Quantum Chemistry and Physical Chemistry, K.U. Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium.
Small. 2011 Sep 5;7(17):2498-506. doi: 10.1002/smll.201100089. Epub 2011 Jul 11.
The fields of bioscience and nanomedicine demand precise thermometry for nanoparticle heat characterization down to the nanoscale regime. Since current methods often use indirect and less accurate techniques to determine the nanoparticle temperature, there is a pressing need for a direct and reliable element-specific method. In-situ extended X-ray absorption fine structure (EXAFS) spectroscopy is used to determine the thermo-optical properties of plasmonic branched gold nanoparticles upon resonant laser illumination. With EXAFS, the direct determination of the nanoparticle temperature increase upon laser illumination is possible via the thermal influence on the gold lattice parameters. More specifically, using the change of the Debye-Waller term representing the lattice disorder, the temperature increase is selectively measured within the plasmonic branched nanoparticles upon resonant laser illumination. In addition, the signal intensity shows that the nanoparticle concentration in the beam more than doubles during laser illumination, thereby demonstrating that photothermal heating is a dynamic process. A comparable temperature increase is measured in the nanoparticle suspension using a thermocouple. This good correspondence between the temperature at the level of the nanoparticle and at the level of the suspension points to an efficient heat transfer between the nanoparticle and the surrounding medium, thus confirming the potential of branched gold nanoparticles for hyperthermia applications. This work demonstrates that X-ray absorption spectroscopy-based nanothermometry could be a valuable tool in the fast-growing number of applications of plasmonic nanoparticles, particularly in life sciences and medicine.
生物科学和纳米医学领域需要精确的测温技术，以便在纳米尺度上对纳米粒子的热特性进行表征。由于目前的方法通常使用间接的、不太准确的技术来确定纳米粒子的温度，因此迫切需要一种直接、可靠的元素特异性方法。本文采用原位扩展 X 射线吸收精细结构（EXAFS）光谱法，在共振激光照射下，测定了等离子体支化金纳米粒子的热光特性。通过 EXAFS，可以通过对金晶格参数的热影响，直接确定激光照射下纳米粒子的温度升高。更具体地说，通过代表晶格无序的德拜-沃勒项的变化，可以选择性地测量在共振激光照射下等离子体支化纳米粒子内的温度升高。此外，信号强度表明，在激光照射过程中，光束中的纳米粒子浓度增加了一倍以上，这表明光热加热是一个动态过程。在使用热电偶的纳米粒子悬浮液中测量到了相当的温度升高。这表明在纳米粒子水平和悬浮液水平上的温度之间存在良好的对应关系，这表明纳米粒子与周围介质之间存在有效的热传递，从而证实了支化金纳米粒子在热疗应用中的潜力。这项工作表明，基于 X 射线吸收光谱的纳米测温技术可能成为等离子体纳米粒子日益增多的应用的一种有价值的工具，特别是在生命科学和医学领域。
