title: Synthesis route and three different core-shell impacts on magnetic characterization of gadolinium oxide-based nanoparticles as new contrast agents for molecular magnetic resonance imaging.
abstract: Despite its good resolution, magnetic resonance imaging intrinsically has low sensitivity. Recently, contrast agent nanoparticles have been used as sensitivity and contrast enhancer. The aim of this study was to investigate a new controlled synthesis method for gadolinium oxide-based nanoparticle preparation. For this purpose, diethyleneglycol coating of gadolinium oxide (Gd2O3-DEG) was performed using new supervised polyol route, and small particulate gadolinium oxide (SPGO) PEGylation was obtained with methoxy-polyethylene-glycol-silane (550 and 2,000 Da) coatings as SPGO-mPEG-silane550 and 2,000, respectively. Physicochemical characterization and magnetic properties of these three contrast agents in comparison with conventional Gd-DTPA were verified by dynamic light scattering transmission electron microscopy, Fourier transform infrared spectroscopy, inductively coupled plasma, X-ray diffraction, vibrating sample magnetometer, and the signal intensity and relaxivity measurements were performed using 1.5-T MRI scanner.As a result, the nanoparticle sizes of Gd2O3-DEG, SPGO-mPEG-silane550, and SPGO-mPEG-silane2000 could be reached to 5.9, 51.3, 194.2 nm, respectively. The image signal intensity and longitudinal (r1) and transverse relaxivity (r2) measurements in different concentrations (0.3 to approximately 2.5 mM), revealed the r2/r1 ratios of 1.13, 0.89, 33.34, and 33.72 for Gd-DTPA, Gd2O3-DEG, SPGO-mPEG-silane550, and SPGO-mPEG-silane2000, respectively.The achievement of new synthesis route of Gd2O3-DEG resulted in lower r2/r1 ratio for Gd2O3-DEG than Gd-DTPA and other previous synthesized methods by this and other groups. The smaller r2/r1 ratios of two PEGylated-SPGO contrast agents in our study in comparison with r2/r1 ratio of previous PEGylation (r2/r1 = 81.9 for mPEG-silane 6,000 MW) showed that these new three introduced contrast agents could potentially be proper contrast enhancers for cellular and molecular MR imaging.
authors.affiliation: Medical Physics & Biomedical Engineering Department, School of Medicine, Tehran University of Medical Sciences (TUMS), Keshavaz blvd, 16 Azar St,, Tehran 14145, Iran. riahinad@sina.tums.ac.ir.
authors.forename: Gholamreza
authors.initials: G
authors.lastname: Azizian
authors.forename: Nader
authors.initials: N
authors.lastname: Riyahi-Alam
authors.forename: Soheila
authors.initials: S
authors.lastname: Haghgoo
authors.forename: Hamid Reza
authors.initials: HR
authors.lastname: Moghimi
authors.forename: Reza
authors.initials: R
authors.lastname: Zohdiaghdam
authors.forename: Behrooz
authors.initials: B
authors.lastname: Rafiei
authors.forename: Ensieh
authors.initials: E
authors.lastname: Gorji