Efficient renal clearance has been observed from ultrasmall zwitterionic glutathione-coated gold nanoparticles (GS-AuNPs), which have broad preclinical applications in cancer diagnosis and kidney functional imaging. However, origin of such efficient renal clearance is still not clear. Herein, we conducted head-to-head comparison on physiological stability and renal clearance of two zwitterionic luminescent AuNPs coated with cysteine and glycine-cysteine (Cys-AuNPs and Gly-Cys-AuNPs), respectively. While both of them exhibited similar surface charges and the same core sizes, additional glycine slightly increased the hydrodynamic diameter of the AuNPs by 0.4 nm but significantly enhanced physiological stability of the AuNPs as well as altered their clearance pathways. These studies indicate that the ligand length, in addition to surface charges and size, also plays a key role in the physiological stability and renal clearance of ultrasmall zwitterionic inorganic NPs.

中文翻译：

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超小两性离子金纳米粒子的生理稳定性和肾脏清除率：配体长度很重要

从超小两性离子谷胱甘肽包被的金纳米粒子 (GS-AuNPs) 中观察到有效的肾脏清除，其在癌症诊断和肾功能成像中具有广泛的临床前应用。然而，这种有效的肾脏清除的起源仍不清楚。在此，我们对分别包覆有半胱氨酸和甘氨酸-半胱氨酸（Cys-AuNPs 和 Gly-Cys-AuNPs）的两种两性离子发光 AuNPs 的生理稳定性和肾脏清除率进行了头对头比较。虽然它们都表现出相似的表面电荷和相同的核心尺寸，但额外的甘氨酸使 AuNPs 的流体动力学直径略微增加了 0.4 nm，但显着增强了 AuNPs 的生理稳定性并改变了它们的清除途径。这些研究表明，配体长度、