Casar Jason R, McLellan Claire A, Siefe Chris, Dionne Jennifer A
Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States.
Department of Materials Science and Engineering and Department of Radiology, Molecular Imaging Program, Stanford University, Stanford, California 94305, United States.
ACS Photonics. 2021 Jan 20;8(1):3-17. doi: 10.1021/acsphotonics.0c00894. Epub 2020 Oct 16.
Lanthanide nanoparticles (LNPs) are promising sensors of chemical, mechanical, and temperature changes; they combine the narrow-spectral emission and long-lived excited states of individual lanthanide ions with the high spatial resolution and controlled energy transfer of nanocrystalline architectures. Despite considerable progress in optimizing LNP brightness and responsiveness for dynamic sensing, detection of stimuli with a spatial resolution approaching that of individual nanoparticles remains an outstanding challenge. Here, we highlight the existing capabilities and outstanding challenges of LNP sensors, en-route to nanometer-scale, single particle sensor resolution. First, we summarize LNP sensor read-outs, including changes in emission wavelength, lifetime, intensity, and spectral ratiometric values that arise from modified energy transfer networks within nanoparticles. Then, we describe the origins of LNP sensor imprecision, including sensitivity to competing conditions, interparticle heterogeneities, such as the concentration and distribution of dopant ions, and measurement noise. Motivated by these sources of signal variance, we describe synthesis characterization feedback loops to inform and improve sensor precision, and introduce noise-equivalent sensitivity as a figure of merit of LNP sensors. Finally, we project the magnitudes of chemical and pressure stimulus resolution achievable with single LNPs at nanoscale resolution. Our perspective provides a roadmap for translating ensemble LNP sensing capabilities to the single particle level, enabling nanometer-scale sensing in biology, medicine, and sustainability.
镧系纳米粒子（LNPs）是很有前景的化学、机械和温度变化传感器；它们将单个镧系离子的窄光谱发射和长寿命激发态与纳米晶体结构的高空间分辨率和可控能量转移结合在一起。尽管在优化LNP亮度和动态传感响应性方面取得了相当大的进展，但以接近单个纳米粒子的空间分辨率检测刺激仍然是一个突出的挑战。在这里，我们强调了LNP传感器在实现纳米级单粒子传感器分辨率的过程中现有的能力和突出的挑战。首先，我们总结了LNP传感器的读出方式，包括纳米粒子内修改后的能量转移网络引起的发射波长、寿命、强度和光谱比率值的变化。然后，我们描述了LNP传感器不精确性的来源，包括对竞争条件的敏感性、粒子间的异质性，如掺杂离子的浓度和分布，以及测量噪声。受这些信号变化来源的推动，我们描述了合成表征反馈回路以告知并提高传感器精度，并引入噪声等效灵敏度作为LNP传感器的品质因数。最后，我们预测了在纳米级分辨率下单个LNP可实现的化学和压力刺激分辨率的大小。我们的观点为将整体LNP传感能力转化为单粒子水平提供了路线图，从而实现生物学、医学和可持续性方面的纳米级传感。
