Superparamagnetic iron oxide nanoparticles with a dendritic polyglycerol (dPG) sulfate strongly bind to L- and P-selectin. Shielding of leukocytes reduces cell extravasation and binding to endothelial cells indicate inflammation specificity and thus, applicability as selective MRI contrast agent.

5–6 nm gold nanoparticles were prepared by hydrolytic decomposition of [NMe₄][Au(CF₃)₂] and functionalizedin situwith mono- and multivalent thiolated PEG ligands. Time-dependent changes of the nanoparticles were monitored in aqueous NaCl, NaBr, and NaI solutions by UV-Vis spectroscopy, TEM, and HRTEM. The purely sterically protected particles are stable in ≤1 M NaCl and NaBr solutions, regardless of the valence of the ligands. At higher concentrations (≥2 M), the monovalent stabilized particles show minor reaction limited colloidal aggregation. In NaBr but not in NaCl solutions a minor Ostwald ripening also occurs. The divalent stabilized particles remain colloidally stable in both halide solutions, even if the temperature is raised or the concentration is increased above 2 M. In ≤1 M aqueous NaI solutions the particles remain stable. Above, the monovalent stabilized particles undergo an oxidative reaction, resulting in a time-dependent shift and broadening of the absorbance spectrum. Finally, this process slows down while the width of the spectra slightly narrows. The kinetics of this process can be described by a two-step sigmoidal process, comprising a slow induction period where active species are formed, followed by a fast growth and aggregation process. The increasing concentration of fused structures from the aggregates during this process results in a narrowing of the size distributions. The divalent stabilized particles show only some minor broadening and a slight shift of the absorbance spectra in ≤3 M NaI solutions. These observations confirm the excellent stability of the multivalent stabilized particles from this chloride-free particle synthesis.