XPCS at the microsecond frontier: diffusion of PEGylated nanoparticles in water

Journal
Materials advances  
Volume
7
Issue
10
Article Number
5065
Citation
Materials Advances 7 (10): 5065 (2026)
Publisher DOI
10.1039/d6ma00387g
Publisher
Royal Society of Chemistry (RSC)
Probing nanoscale transport in liquids under extreme thermodynamic conditions is essential for understanding soft matter and nanomaterials. However, accessing intrinsic microsecond dynamics of nanometre-sized objects remains challenging for synchrotron-based X-ray photon correlation spectroscopy (XPCS) because of limitations of coherent flux and detector repetition rates. Here, we investigate the diffusion of dilute polyethylene glycol (PEG)-coated gold nanoparticles dispersed in water over a wide temperature range, including water's supercooled regime using XPCS. The measured dynamics exhibit purely diffusive behaviour, with relaxation rates scaling as q2, and the extracted diffusion coefficients quantitatively follow the Stokes–Einstein relation with no slip boundary condition. Viscosity values derived from nanoparticle motion agree with established literature data, confirming that PEGylated nanoparticles act as reliable nanoscopic viscosity probes without evidence of ligand shell compression or structural changes. Using event-based XPCS with next-generation detectors, we access microsecond dynamics approaching the intrinsic Brownian timescale of nanometer-sized particles. These results establish PEGylated gold nanoparticles as robust probes of nanoscale transport and demonstrate the capability of advanced XPCS instrumentation to investigate fast dynamics in soft and nanoscale materials.
DDC Class
530.42: Fluid Physics
620.5: Nanotechnology
620.11: Engineering Materials
Lizenz
https://creativecommons.org/licenses/by/4.0/
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