X-ray photon correlation spectroscopy (XPCS), a synchrotron source-based technique to measure sample dynamics, is used to determine hydrodynamic diameters of gold nanoparticles (Au NPs) of different sizes in biological environments. In situ determined hydrodynamic diameters are benchmarked with values obtained by dynamic light scattering. The technique is then applied to analyze the behavior of the Au NPs in a biological environment. First, a concentration-dependent agglomeration in the presence of NaCl is determined. Second, concentration-dependent increase in hydrodynamic diameter of the Au NPs upon the presence of proteins is determined. As X-rays in the used energy range are barely scattered by biological matter, dynamics of the Au NPs can be also detected in situ in complex biological environments, such as blood. These measurements demonstrate the possibility of XPCS for in situ analytics of nanoparticles (NPs) in biological environments where similar detection techniques based on visible light would severely suffer from scattering, absorption, and reflection effects.

中文翻译：

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X 射线光子相关光谱法用于测量生物环境中的纳米粒子直径，允许对其生物纳米界面进行原位分析

X 射线光子相关光谱 (XPCS) 是一种基于同步加速器源的样品动力学测量技术，用于确定生物环境中不同尺寸的金纳米粒子 (Au NPs) 的流体动力学直径。原位确定的流体动力学直径以通过动态光散射获得的值作为基准。然后将该技术应用于分析金纳米粒子在生物环境中的行为。首先，确定在 NaCl 存在下的浓度依赖性聚集。其次，确定了在蛋白质存在时Au NPs 流体动力学直径的浓度依赖性增加。由于所用能量范围内的 X 射线几乎不会被生物物质散射，因此也可以在复杂的生物环境（例如血液）中原位检测 Au NPs 的动力学。