Currently, superparamagnetic functionalized systems of magnetite (FeO) nanoparticles (NPs) are promising options for applications in hyperthermia therapy, drug delivery and diagnosis. FeO NPs below 20 nm have stable single domains (SSD), which can be oriented by magnetic field application. Dispersion of FeO NPs in silicon dioxide (SiO) matrix allows local SSD response with uniaxial anisotropy and orientation to easy axis, 90° <001> or 180° <111>. A successful, easy methodology to produce FeO NPs (6-17 nm) has been used with the Stöber modification. NPs were embedded in amorphous and biocompatible SiO matrix by mechanical stirring in citrate and tetraethyl orthosilicate (TEOS). FeO NPs dispersion was sampled in the range of 2-12 h to observe the SiO matrix formation as time function. TEM characterization identified optimal conditions at 4 h stirring for separation of SSD FeO in SiO matrix. Low magnetization (M) of 0.001 emu and a coercivity (H) of 24.75 Oe indicate that the embedded SSD FeO in amorphous SiO reduces the M by a diamagnetic barrier. Magnetic force microscopy (MFM) showed SSD FeO of 1.2 nm on average embedded in SiO matrix with uniaxial anisotropy response according to Fe and Fe electron spin coupling and rotation by intrinsic Neél contribution.