Institut National de la Recherche Scientifique, Centre Énergie Matériaux Télécommunications, Université du Québec, Varennes, Québec J3X 1S2, Canada.
Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari di Venezia, Via Torino 155/b, I-30170, Venezia-Mestre, Italy.
Nanoscale. 2017 Mar 2;9(9):3079-3085. doi: 10.1039/c6nr08472a.
Owing to the alluring possibility of contactless temperature probing with microscopic spatial resolution, photoluminescence nanothermometry at the nanoscale is rapidly advancing towards its successful application in biomedical sciences. The emergence of near-infrared nanothermometers has paved the way for temperature sensing at the deep tissue level. However, water dispersibility, adequate size at the nanoscale, and the capability to efficiently operate in the second and third biological optical transparency windows are the requirements that still have to be fulfilled in a single nanoprobe. In this work, these requirements are addressed by rare-earth doped nanoparticles with core/shell-architecture, dispersed in water, whose excitation and emission wavelengths conveniently fall within the biological optical transparency windows. Under heating-free 800 nm excitation, double nanothermometry is realized either with Ho-Nd (1.18-1.34 μm) or Er-Nd (1.55-1.34 μm) NIR emission band ratios, both displaying equal thermal sensitivities around 1.1% °C. It is further demonstrated that, along with the interionic energy transfer processes, the thermometric properties of these nanoparticles are also governed by the temperature dependent energy transfer to the surrounding solvent (water) molecules. Overall, this work presents a novel water dispersible double ratiometric nanothermometer operating in the second and third biological optical transparency windows. The temperature dependent particle-solvent interaction is also presented, which is critical for e.g. future in vivo applications.
由于具有非接触式微区空间分辨率温度探测的诱人可能性，纳米发光光热计量学正迅速朝着在生物医学科学中成功应用的方向发展。近红外光热计的出现为深层组织的温度传感铺平了道路。然而，水的分散性、纳米级的足够尺寸以及在第二和第三生物光学透明窗口中高效运行的能力，仍然是单个纳米探针需要满足的要求。在这项工作中，通过具有核/壳结构的掺杂稀土纳米粒子来满足这些要求，这些纳米粒子在水中分散，其激发和发射波长方便地落在生物光学透明窗口内。在无加热的 800nm 激发下，通过 Ho-Nd（1.18-1.34μm）或 Er-Nd（1.55-1.34μm）NIR 发射带比值来实现双光热计量，两者的热灵敏度均在 1.1%℃左右。进一步证明，除了离子间能量转移过程外，这些纳米粒子的热计量性能还受到周围溶剂（水）分子的温度相关能量转移的影响。总的来说，这项工作提出了一种新型的水可分散双比率纳米光热计，可在第二和第三生物光学透明窗口中运行。还提出了粒子-溶剂相互作用的温度依赖性，这对于例如未来的体内应用至关重要。
