Dong Juyao, Zink Jeffrey I
Department of Chemistry and Biochemistry, University of California, Los Angeles , 607 Charles E. Young Drive East, Los Angeles, California 90095, United States.
ACS Nano. 2014 May 27;8(5):5199-207. doi: 10.1021/nn501250e. Epub 2014 May 5.
The temperature increase inside mesoporous silica nanoparticles induced by encapsulated smaller superparamagnetic nanocrystals in an oscillating magnetic field is measured using a crystalline optical nanothermometer. The detection mechanism is based on the temperature-dependent intensity ratio of two luminescence bands in the upconversion emission spectrum of NaYF4:Yb(3+), Er(3+). A facile stepwise phase transfer method is developed to construct a dual-core mesoporous silica nanoparticle that contains both a nanoheater and a nanothermometer in its interior. The magnetically induced heating inside the nanoparticles varies with different experimental conditions, including the magnetic field induction power, the exposure time to the magnetic field, and the magnetic nanocrystal size. The temperature increase of the immediate nanoenvironment around the magnetic nanocrystals is monitored continuously during the magnetic oscillating field exposure. The interior of the nanoparticles becomes much hotter than the macroscopic solution and cools to the temperature of the ambient fluid on a time scale of seconds after the magnetic field is turned off. This continuous absolute temperature detection method offers quantitative insight into the nanoenvironment around magnetic materials and opens a path for optimizing local temperature controls for physical and biomedical applications.
利用晶体光学纳米温度计测量了在振荡磁场中由封装的较小超顺磁性纳米晶体引起的介孔二氧化硅纳米颗粒内部的温度升高。检测机制基于NaYF4:Yb(3+)、Er(3+)上转换发射光谱中两个发光带的温度依赖性强度比。开发了一种简便的逐步相转移方法来构建一种双核介孔二氧化硅纳米颗粒，其内部同时包含一个纳米加热器和一个纳米温度计。纳米颗粒内部的磁诱导加热随不同的实验条件而变化，包括磁场感应功率、磁场暴露时间和磁性纳米晶体尺寸。在磁振荡场暴露期间，连续监测磁性纳米晶体周围紧邻的纳米环境的温度升高。纳米颗粒内部比宏观溶液热得多，并且在磁场关闭后的几秒钟时间尺度内冷却至周围流体的温度。这种连续的绝对温度检测方法为深入了解磁性材料周围的纳米环境提供了定量依据，并为优化物理和生物医学应用中的局部温度控制开辟了一条途径。
