The process of Gd/SiO2 nanoparticles synthesis published recently by Santra et al. [24] was slightly modified in our work, i.e. without final amine-functionalization and using similar reagents: N-[3-(trimethoxysilyl)propyl] ethylenediamine for capturing of paramagnetic Gd3+ ions and 3-(trihydroxy-silyl)propyl methylphosphonate monosodium salt solution to produce highly water dispersible nanoparticles. All reagents were purchased from Aldrich, except NH4OH (Fluka).Approximate particle size of samples was determined using Scanning Electron Microscopy (SEM, model FEI Quantum 200). For SEM analysis, samples were placed on conductive copper sticking tape. The structure of the samples was checked by X-ray diffraction (XRD) using X��PERT diffractometer from PANalytical and CoK�� radiation with qualitative analysis carried out by HighScore software and the JCPDS PDF-2 database.

For a quantitative analysis of the XRD patterns, we took HighScore plus with Rietveld structural models based on the ICSD database. 57Fe M?ssbauer spectra used for phase analysis were measured using 57Co/Rh source in standard transmission at room temperature and in a cryostat down to 28 K. Spectrum calibrations were done using ��-Fe standard. The computer processing of the spectra yielded intensities I of the components (atomic fraction of Fe atoms), their hyperfine inductions Bhf, isomer shifts ��, quadrupole splittings ��EQ, and quadrupole shifts ��Q. The magnetic measurements were carried out using vibrating sample magnetometer at room temperature in an external magnetic field up to 1 T.3.

?Results and DiscussionThe obtained Fe2O3/SiO2 and Fe2O3 powders were brownish-black and reddish-brown, respectively, while Gd/SiO2 nanoparticles were orange due to their doping by fluorescent dye, tris(2,2��-bipyridyl) dichlororuthenium(II) hexahydrate. Only Fe2O3 nanoparticles revealed the magnetic properties in water suspension when external magnetic field was applied (Figure 1.).Figure 1.Magnetic properties illustration of Fe2O3 nanoparticles dispersed in water.SEM analysis demonstrated that the nanoparticles of all prepared samples have particle sizes below 100 nm (Figure 2.). The particles were generally spherical in the shape. However it can be supposed that the size distribution for all samples is rather wide.Figure 2.SEM image of Fe2O3 (left) and GdIII/SiO2 (right).

According to XRD measurement (XRD patterns of all samples are shown in Figure 3.), GdIII/SiO2 nanoparticles were found to be completely Entinostat amorphous. The orthorhombic ��-Fe2O3 was observed as
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