Lanthanide nanoparticles (LnNPs) feature sharp emission lines together with millisecond emission lifetimes which make them promising luminescent probes for biosensing and bioimaging. Although LnNPs are attracting much interest, their photoluminescence properties at the single nanoparticle level remain largely unexplored. Here, we employ fluorescence correlation spectroscopy (FCS) and photoluminescence burst analysis to investigate the photodynamics of Sm- and Eu-based LnNPs with single nanoparticle sensitivity and microsecond resolution. By recording the photoluminescence intensity and the number of contributing LnNPs, we compute the photoluminescence brightness per individual nanoparticle and estimate the actual number of emitting centers per nanoparticle. Our approach overcomes the challenges associated with ensemble-averaged techniques and provides insights into LnNP photodynamics. Moreover, we demonstrate our microscope's ability to detect and analyze LnNPs at the single nanoparticle level, monitoring both photoluminescence brightness and burst duration. These findings expand our understanding of LnNPs and pave the way for advanced biosensing applications at the single nanoparticle level.

中文翻译：

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一次观察一个镧系元素纳米粒子：在单个纳米粒子水平上表征它们的光致发光动力学


镧系元素纳米颗粒 （LnNPs） 具有清晰的发射线和毫秒级发射寿命，这使它们成为生物传感和生物成像的发光探针。尽管 LnNP 引起了人们的广泛兴趣，但它们在单个纳米颗粒水平上的光致发光特性在很大程度上仍未得到探索。在这里，我们采用荧光相关光谱 （FCS） 和光致发光爆发分析来研究具有单纳米颗粒灵敏度和微秒分辨率的 Sm 和 Eu 基 LnNPs 的光动力学。通过记录光致发光强度和贡献的 LnNP 的数量，我们计算每个纳米颗粒的光致发光亮度，并估计每个纳米颗粒的实际发射中心数量。我们的方法克服了与集成平均技术相关的挑战，并提供了对 LnNP 光动力学的见解。此外，我们展示了我们的显微镜在单个纳米颗粒水平上检测和分析 LnNP 的能力，同时监测光致发光亮度和爆发持续时间。这些发现扩展了我们对 LnNPs 的理解，并为单个纳米颗粒水平的先进生物传感应用铺平了道路。