Table 1.

Surface modification of SPIONs and their physical properties at room temperature in aqueous dispersion (pH 7, DLS = dynamic light scattering).

Surface modification	Linker structure	Zeta potential	Average diameter (DLS)
None (pure silica)	—	−59 mV	136 nm
Carboxylic acid		−47 mV	157 nm
Polyethylene glycol		−14 mV	133 nm