Live Monitoring of Nanoparticle Aggregation and Sedimentation in Biological Fluids Using X-ray Photon Correlation Spectroscopy

Aggregation and sedimentation greatly impact the behavior and functionality of nanoparticles in biological environments. Monitoring the aggregation and sedimentation of nanoparticles in vivo could help to better understand and control their colloidal behaviors. However, this task is often hindered by abundant biomolecules in biological fluids and biological barriers such as skin and blood vessels. X-ray photon correlation spectroscopy (XPCS) is an emerging X-ray technique to study nanoscale dynamics, which has yielded fruitful results for various biological samples in recent years. In this work, we use time-resolved XPCS to monitor protein-induced aggregation and sedimentation of silica nanoparticles in solution, which brings about additional temporal information to this dynamic process. Three protein concentration regimes are identified: the stable regime, the sedimentation regime, and the restabilized regime. Furthermore, XPCS measurements are successfully carried out in a biomimicking vessel, demonstrating the feasibility of using XPCS to monitor nanoparticle dynamics in vivo.