Fabrication and Surface-Modification of Silica/Gadolinium Compound/Silica Core-Shell Nanoparticles Discovered by Transmission Electron Microscopy

Abstract

The present work describes methods for fabricating multilayered core-shell nanoparticles composed of silica (SiO2) as a core, gadolinium compound (GdC) as an inner shell, and SiO2 as an outer shell (SiO2/GdC/SiO2) toward colloidally-stable, inert magnetic resonance imaging contrast agent, and for surface-modifying the SiO2/GdC/SiO2 nanoparticles toward immobilization of functional molecules on the SiO2/GdC/SiO2.SiO2 nanoparticles (particle size by transmission electron microscopy (TEM): 28.6±12.6nm) were produced by a sol-gel method using tetraethylorthosilicate (TEOS) and methylamine in water/ethanol solution.GdC-coated SiO2 nanoparticles (SiO2/GdC) (GdC shell thickness by TEM: 35.9±4.9 nm) were synthesized by a homogeneous precipitation method using water/propanol solution containing the SiO2 nanoparticles, Gd(NO3)3, urea and polyvinylpyrrolidone. Succeeding SiO2coating of the SiO2/GdC nanaoparticles was performed by using TEOS and NaOH in the presence of SiO2/GdC nanoparticles.Consequently, SiO2/GdC/SiO2 nanoparticles (SiO2 shell thickness by TEM: 8.5±2.7 nm) could be obtained.The SiO2/GdC/SiO2 nanoparticles were successfully surface-modified by using 3aminopropyltrimethoxysilane for amination, and by followingly using succinic anhydride for carboxylation.