Effect of Graft Molecular Weight On the Colloidal Stability of Iron Oxide Nanoparticles with Grafted Poly(ethylene glycol)

We studied the stability of colloidal suspensions of iron oxide nanoparticles with grafted poly(ethylene glycol) of various molecular weights in aqueous media, buffers, and cell culture media. The particles consist of iron oxide cores with narrow particle size distribution and coated with individual polymer coronas. Particle surface charge and hydrodynamic size were studied as a function of pH and ionic strength using zeta potential measurements and dynamic light scattering. DLVO theory was used to model particle-particle interactions, which were correlated to aggregation state as determined from experimental measurements.