Synthesis and structural characterization of silica particles doped with Dy and Gd paramagnetic ions as MRI contrast agents

[Display omitted] •Gd or/and Dy containing silica submicronic particles obtained by Stöber method.•Investigation of structure, morphology and NMR relaxivity.•Potential applications as contrast agents for magnetic resonance imaging (MRI). Silica submicronic particles doped with Dy and Gd paramagnetic ions were successfully synthesized by using chemical synthesis based on the modified Stöber method, having potential applications as contrast agents for magnetic resonance imaging (MRI). Structural characterization analyses show an amorphous character of the particles (XRD), good thermal stability (DTA), and spheroid shape (SEM). The integration of paramagnetic ions into the silica network was demonstrated by the TEM, EPR and FTIR spectroscopies. The magnetic resonance (MR) relaxivity examinations of the samples show a high rate of relaxivity for the particles doped with Dy, making them suitable as T2 contrast agent for magnetic resonance imaging. This is in contrast to the results obtained on the particles doped with Gd, which are an effective T1-weighted MRI contrast agent. Notably, if the silica structure incorporates both Gd and Dy the particles are suitable for contrast enhancement in both T1 and T2 weighted images. These characteristics of the samples are also supported by the value of the relaxivity ratio (r2/r1) for the three samples doped with paramagnetic ions. The results confirm the sustainability of MRI contrast agent applications for all three synthesized samples.