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In this study, hydrophilic and biocompatible chitosan oligosaccharide lactate (COL)-coated ultra-small gadolinium oxide nanoparticles (NPs) were synthesized through a one-pot polyol method and characterized by various experimental techniques. The In Vitro cellular cytotoxicity assay indicated that the COL-coated gadolinium oxide NPs were non-toxic up to 500 μM Gd. In addition, their water proton spin relaxivities (i.e., r1 and r2) were estimated to be 13.0 and 27.0 s−1mM−1, respectively, which are higher than those of commercial magnetic resonance imaging (MRI) contrast agents. The application potential of the solution sample as a T1 MRI contrast agent was demonstrated In Vitro by measuring map images in which dose-dependent contrast enhancements were observed.

An increased understanding of how odors are processed in the central nervous system may provide comprehensive information about the neural basis of odor-related behavior and learning. In this study, we investigated how different odors are processed from the olfactory bulb to the deep cerebral structures through various olfactory pathways. To do this, we employed a novel manganese-enhanced magnetic resonance imaging (MEMRI) method to map the activity-dependent functional connectivity of the olfactory and non-olfactory pathways associated with various odorants. Our MEMRI data revealed odor-specific neural pathways that correspond to different odorant stimulations, suggesting that different neural circuits may process different odorants. Among the odorants tested, formic acid, an alarm pheromone, stimulated not only the primary and secondary olfactory pathways but also the mesolimbic neural circuit, which overlaps with the dopaminergic neural pathway. Linalool, which is a major component of aroma oils, showed high Mn2+ uptake in the hypothalamus, which plays a role in the stress response through the secretion of corticotropin-releasing hormone (CRH), and consequently, the stimulation of corticotropin secretion. Acetone mainly activated the primary olfactory pathway, whereas saline acted as a non-odorous trigeminal stimulus. Taken together, our functional MEMRI using anatomic standardization and statistical analyses could be a promising in vivo imaging method to map neural connectivity, enabling further understanding of the neural processing of different odorants.

This study investigates how moderate and addictive exercise influence the executive function network of the brain using fMRI. Sixty-five healthy participants performed the Wisconsin Card Sorting Test (WCST) during a functional magnetic resonance imaging (fMRI) scan. Participants were divided into three groups, according to the Korean exercise addiction scale (K-EAS): addictive exercise (AE), moderate exercise (ME), and no exercise (NE). We compared the extracted volumes of activity from the fMRI data between groups and analyzed the correlation between the volumes and the behavioral data. The activated area in the executive function network was significantly smaller in the AE and ME groups than in the NE group. In contrast, there was no difference between the AE and the ME group in the size of the activated area of the executive function network. The groups did not differ in behavioral performance. There was no significant correlation between the behavioral measurements and the activation volumes. A focused reorganization of the executive brain network through exercise may suggest improved neural efficiency for executive functions, and exercise may be helpful in maintaining executive functions and behavioral performance levels. Addictive exercise did not show an added benefit for the efficiency of executive functions.

D-glucuronic acid-coated ultrasmall chromium oxide (Cr2O3) nanoparticles were synthesized by a one-pot polyol method and their relaxometric and optical properties were investigated. The as-synthesized D-glucuronic acid-coated nanoparticles were amorphous owing to ultrasmall particle diameters (davg = 2.0 nm), whereas orthorhombic Cr2O3 nanoparticles with two size groups (davg = 3.6 and 5.7 nm) were observed after thermogravimetric analysis (900 °C) as a result of particle growth. The nanoparticles exhibited size-dependent UV-visible absorption maxima at 238, 274, and 372 nm with increasing particle diameter, corresponding to band gaps of 5.13, 4.45, and 3.28 eV, respectively. D-glucuronic acid-coated ultrasmall Cr2O3 nanoparticles revealed low water proton relaxivities of r1 = 0.05 s-1mM-1 and r2 = 0.20 s-1mM-1, consistent with the antiferromagnetic property of Cr2O3. They showed good biocompatibility up to 500 μM of Cr.

Mixed Zn(II)/Gd(III) oxide nanoparticles (~8 mole%Zn) with d(avg) of 2.1 nm were synthesized. The D-glucuronic acid coated Zn(II)/Gd(III) oxide nanoparticles showed a longitudinal water proton relaxivity (r₁) of 12.3 s⁻¹mM⁻¹ with r₂/r₁ = 1.1, corresponding to an ideal condition for T₁ MRI contrast agent. We attribute this to reduced magnetization of the mixed nanoparticles owing to non-magnetic Zn in the nanoparticles. Their effectiveness as a T₁ MRI contrast agent was confirmed by acquiring In Vivo T₁ MR images of a mouse after intravenous injection.

This work is directed toward the synthesis of two types of gadolinium oxide nanoparticles (Gd-oxide NPs), abbreviated as Gd@SiO2-DO3A and Gd@SiO2-DO2A-BTA, with diameters of 50-60 nm. The synthesis involves sequential coating of Gd-oxide NPs with tetraethyl orthosilicate (TEOS) and (3-aminopropyl) triethoxysilane (APTES), followed by functionalization of the aminopropylsilane group with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) or 1,4,7,10-tetraazacyclododecane-1,4,7-trisacetic acid conjugates of benzothiazoles (DO3A-BTA). Gd@SiO2-DO3A and Gd@SiO2-DO2A-BTA exhibit high water solubility and colloidal stability. The r1 relaxivities of both Gd@SiO2-DO3A and Gd@SiO2-DO2A-BTA are higher than those of the corresponding low-molecular-weight magnetic resonance imaging contrast agents (MRI CAs), and their r2/r1 ratios are close to 1, indicating that both can be used as potential T1 MRI CAs. Biodistribution studies demonstrated that Gd@SiO2-DO2A-BTA was excreted via both hepatobiliary and renal pathways. Gd@SiO2-DO2A-BTA exhibits a strong intracellular uptake property in a series of tumor cell lines, and has significant anticancer characteristics against cell lines such as SK-HEP-1, MDA-MB-231, HeLa, and Hep-3B.

The gadolinium oxide (Gd2O3) nanoparticles are well-known potential candidates for a positive magnetic resonance imaging (MRI) contrast agent owing to their large longitudinal water proton relaxivity (r1) value with r2/r1 ratio close to one (r2 = transverse water proton relaxivity). In addition they may be used to sense metal ions because their r1 and r2 values can be altered in the presence of metal ions. This may allow us to study metabolic processes involving metal ions and to diagnose disease related to abnormal concentrations of metal ions in the body in a non-invasive way. In this study ultrasmall Gd2O3 nanoparticles were for the first time applied to non-specifically sense Zn2+ ions in aqueous solution. We explored this by measuring r1 and r2 values in the presence of Zn2+ ions in solution.

T2 MRI contrast agents cannot be synthesized by using molecules but nanoparticles because appreciable magnetic moments at room temperature are needed. Recently, some of lanthanide (Ln) oxide nanoparticles have shown decent magnetic moments at room temperature and even at ultrasmall particle diameters. In this study, we explored D-glucuronic acid coated Ln2O3 nanoparticles (Ln = Ho and Er) with ultrasmall particle diameters. They showed decent magnetic moments at room temperature and as a result, appreciable transverse water proton relaxivities (r2s) at 1.5 tesla MR field. Clear dose-dependent contrast enhancements in R2 map images were observed in both samples. These results showed that D-glucuronic acid coated Ln2O3 nanoparticles (Ln = Ho and Er) would be potential T2 MRI contrast agents at high MR fields.

The water-soluble and biocompatible D-glucuronic acid coated Eu(OH)3 nanorods (average thickness x average length = 9.0 x 118.3 nm) have been prepared in one-pot synthesis. The D-glucuronic acid coated Eu(OH)3 nanorods showed a strong fluorescence at approximately 600 nm with a narrow emission band width. A cytotoxicity test by using DU145 cells showed that D-glucuronic acid coated Eu(OH)3 nanorods are not toxic up to 100 microM, making them a promising candidate for biomedical applications such as fluorescent imaging. The minimum Eu concentration needed for a conventional confocal imaging was estimated to be approximately 0.1 mM. Therefore, D-glucuronic acid coated Eu(OH)3 nanorods can be applied to fluorescent imaging. However, a very tiny magnetization of approximately 1.2 emu/g at room temperature and at an applied field of 5 tesla was observed. As a result, very small r1 and r2 water proton relaxivities were estimated, implying that surface coated Eu(OH)3 nanorods are not sufficient for MRI contrast agents.

Gold-coated iron oxide (Fe3O4) nanoparticles were synthesized for use as a T2 contrast agent in magnetic resonance imaging (MRI). The coated nanoparticles were spherical in shape with an average diameter of 20 nm. The gold shell was about 2 nm thick. The bonding status of the gold on the nanoparticle surfaces was checked using a Fourier transform infrared spectrometer (FTIR). The FTIR spectra confirmed the attachment of homocysteine, in the form of thiolates, to the Au shell of the Au-Fe3O4 nanoparticles. The relaxivity ratio, R2/R1, for the coated nanoparticles was 3-fold higher than that of a commercial contrast agent, Resovist, which showed the potential for their use as a T2 contrast agent with high efficacy. In animal experiments, the presence of the nanoparticles in rat liver resulted in a 71% decrease in signal intensity in T2-weighted MR images, indicating that our gold-coated iron oxide nanoparticles are suitable for use as a T2 contrast agent in MRI.

Reported herein is the synthesis of a dextran coating on nickel ferrite (Ni-Fe2O4) nanoparticles via chemical coprecipitation. The aqueous solution of the synthesized nanoparticles showed good colloidal stability, and no precipitate was observed 20 months after the synthesis. The coated nanoparticles were found to be cylindrical in shape in the TEM images, and showed a uniform size distribution with an average length and diameter of 17 and 4 nm, respectively. The coated particles were evaluated as potential T1 and T2 contrast agents for MRI. The T1 and T2 relaxations of the hydrogen protons in the water molecules in an aqueous solution of dextran-coated Ni-Fe2O4 nanoparticles were studied. It was found that the T1 relaxivity for the aqueous solution of dextran-coated nanoparticles was slightly greater than that of a commercial Gd-DTPA-BMA contrast agent. The T2 relaxivity, however, was almost twice that of the commercial Gd-DTPA-BMA contrast agent. Animal experimentation also demonstrated that the dextran-coated Ni-Fe2O4 nanoparticles are suitable for use as either T1 or T2 contrast agents in MRI.

We report a facile one-pot synthesis of Fe3O4-CdX (X = S, Se) core–shell nanoparticles and characterized them with XRD, TEM, squid magnetometer, and UV-visible absorption and PL spectrometers. We observed that the core Fe3O4 nanoparticles showed a superparamagnetism at room temperature, whereas the shell CdX (X = S, Se) showed blue-shifts from the bulk materials in UV-visible absorption spectra, due to quantum confinement effect. These superparamagnetic and optical properties of the Fe3O4-CdX (X = S, Se) core–shell nanoparticles can be used for both MR and optical imagings. This dual imaging capability will increase a possibility of an early observation of disease such as cancer.