Synthesis and functionalization of magnetite nanoparticles with different amino-functional alkoxysilanes

► Superparamagnetic iron oxide nanoparticles were grafted with different alkoxysilanes. ► The decrease of alkoxide group number reduced the concentration of free amino group. ► We correlate the influence of the amino and ethyl groups with their colloidal property. ► Inter-particles aggregation analyzed by magnetic measurement.