Gas-Phase Modification as Key Process in Design of New Generation of Gd2O3-Based Contrast Agents for Computed Tomography

In the present study, thin-layered core–shell Gd2O3@SiO1.5R (R is C3H6NH2) structures were synthesized by gas-phase surface modification of a Gd2O3 core with a 3-aminopropyltriethoxysilane (APTES) shell for the first time. The proposed method consists of two consecutive steps carried out in a fixed-bed reactor. The first step involves APTES adsorption on the Gd2O3 surface, followed by APTES hydrolysis by water vapor. The organosyloxane shell formation was confirmed by transmission and scanning electron microscopy, IR spectroscopy, and thermogravimetric data. X-ray attenuation coefficients of Gd2O3 and Gd2O3@SiO1.5R samples were determined by photon-counting computed tomography in a phantom study. The SiO1.5R shells in the synthesized Gd2O3@SiO1.5R samples had minimal thickness and did not affect the attenuation coefficients of Gd2O3.