The increasing industrial use of nanomaterials calls for the reliable characterization of their physicochemical key properties like size, size distribution, shape, and surface chemistry, and test and reference materials (RMs) with sizes and shapes, closely matching real-world nonspheric nano-objects. An efficient strategy to minimize efforts in producing nanoscale RMs (nanoRMs) for establishing, validating, and standardizing methods for characterizing nanomaterials are multimethod nanoRMs. Ideal candidates are lanthanide-based, multicolor luminescent, and chemically inert nanoparticles (NPs) like upconversion nanoparticles (UCNPs), which can be prepared in different sizes, shapes, and chemical composition with various surface coatings. This makes UCNPs interesting candidates as standards not only for sizing methods, but also for element-analytical methods like laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS), quantitative bioimaging methods like X-ray fluorescence computed tomography (XFCT), and luminescence methods and correlative measurements. Here, we explore the potential of two monodisperse LiYF₄:Yb,Tm bipyramids with peak-to-peak distances of (43 ± 2) nm and (29 ± 2) nm as size standards for small-angle X-ray scattering (SAXS) and tools for establishing and validating the sophisticated simulations required for the analysis of SAXS data derived from dispersions of nonspheric nano-objects. These SAXS studies are supplemented by two-dimensional (2D)-transmission electron microscopy measurements of the UCNP bipyramids. Additionally, the particle number concentration of cyclohexane dispersions of these UCNP bipyramids is determined by absolute SAXS measurements, complemented by gravimetry, thermogravimetric analysis (TGA), and inductively coupled plasma optical emission spectrometry (ICP-OES). This approach enables traceable particle number concentration measurements of ligand-capped nonspheric particles with unknown chemical composition.

中文翻译：

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为纳米级参考物质添加更多形状 ─ LiYF4：Yb，Tm 双锥体作为定量方法和颗粒数浓度的标准品


纳米材料的工业用途越来越广泛，要求对其物理化学关键特性（如尺寸、尺寸分布、形状和表面化学）以及具有尺寸和形状的测试和参考材料 （RM） 进行可靠表征，以与现实世界的非球形纳米物体紧密匹配。多方法 nanoRM 是一种有效的策略，可以最大限度地减少生产纳米级 RM （nanoRM） 的工作量，以建立、验证和标准化表征纳米材料的方法。理想的候选者是基于镧系元素的、多色发光的和化学惰性的纳米颗粒 （NP），如上转换纳米颗粒 （UCNP），它们可以用各种表面涂层制备成不同的尺寸、形状和化学成分。这使得 UCNP 不仅成为定量方法的标准，而且作为元素分析方法（如激光消融电感耦合等离子体质谱法 （LA-ICP-MS）、定量生物成像方法（如 X 射线荧光计算机断层扫描 （XFCT））以及发光方法和相关测量）的有趣候选者。在这里，我们探讨了两种峰峰值距离为 （43 ± 2） nm 和 （29 ± 2） nm 的单分散 LiYF₄：Yb，Tm 双锥体的潜力，作为小角 X 射线散射 （SAXS） 的尺寸标准，以及用于建立和验证分析来自非球形纳米物体分散的 SAXS 数据所需的复杂模拟的工具。这些 SAXS 研究由 UCNP 双锥体的二维 （2D） 透射电子显微镜测量补充。 此外，这些 UCNP 双锥体的环己烷分散体的颗粒数浓度通过绝对 SAXS 测量确定，并辅以重量法、热重分析 （TGA） 和电感耦合等离子体发射光谱法 （ICP-OES）。这种方法能够对化学成分未知的配体封端非球形颗粒进行可追溯的颗粒数浓度测量。