Mobility of interacting inorganic nanoparticles

The mobility of the 110 nm-Fe₂O₃ particles in a viscous sucrose solution depends on the concentration of the nanoparticles. When the average particle–particle nearest neighbor distance <r> is less than 250 nm, the particle interaction slows down their mobility. When <r> is more than 170 nm, the small mobility of nanoparticles does not depend on their concentration. The critical distance is approximately equal to 2R_h = 260 nm, where R_h is the hydrodynamic radius, determined by the dynamic light scattering (DLS) method.