Kwon-Seok Chae

Kyungpook National University | KNU · Department of Biology Education

Throughout the long history of various therapeutic trials of transcranial magnetic stimulation (TMS), some TMS protocols have been reported to be clearly effective in the treatment of neurodegenerative diseases. Despite promising results from repetitive TMS (rTMS) using low frequency electromagnetic fields (EMFs) for neurodegenerative diseases, the...

The Earth’s geomagnetic field (GMF) is known to influence magnetoreceptive creatures, from bacteria to mammals as a sensory cue or a physiological modulator, despite it is largely thought that humans cannot sense the GMF. Here, we show that humans sense the GMF to orient their direction toward food in a self-rotatory chair experiment. Starved men,...

Certain long-distance migratory animals, such as salmon and sea turtles, are thought to imprint on the magnetic field of their natal area and to use this information to help them return as adults. Despite a growing body of indirect support for such imprinting, direct experimental evidence thereof remains elusive. Here, using the fruit fly as a magn...

Numerous organisms use the Earth’s magnetic field as a sensory cue for migration, body alignment, or food search. Despite some contradictory reports, yet it is generally accepted that humans do not sense the geomagnetic field. Here, we demonstrate that a magnetic field resonance mechanism mediates light-dependent magnetic orientation in men, using...

To resolve disputes or determine the order of things, people commonly use binary choices such as tossing a coin, even though it is obscure whether the empirical probability equals to the theoretical probability. The geomagnetic field (GMF) is broadly applied as a sensory cue for various movements in many organisms including humans, although our und...

Decades of research have established that the Earth’s magnetic field (geomagnetic field, GMF) is broadly used as a sensory cue for magnetic orientation in various animal taxa, including insects. In contrast to the investigation of the total intensity or inclination of the GMF, the effect of declination on horizontal magnetic movement has been explo...

Hydrophilic and biocompatible PAA-coated ultrasmall Gd2O3 nanoparticles (davg = 1.7 nm) were synthesized and conjugated with tumor-targeting ligands, i.e., cyclic arginylglycylaspartic acid (cRGD) and/or folic acid (FA). FA-PAA-Gd2O3 and cRGD/FA-PAA-Gd2O3 nanoparticles were successfully applied in U87MG tumor-bearing mice for tumor imaging using T1...

Paramagnetic ultrasmall Ho2O3 and Tm2O3 nanoparticles (davg = ∼2.1 nm) grafted with various hydrophilic and biocompatible ligands such as poly(ethylene glycol) diacid (Mn = 250 and 600 amu) and polyacrylic acid (Mw = 1800 amu) were synthesized via a one-pot polyol method. Appreciable transverse (r2) and negligible longitudinal (r1) water proton spi...

Water proton spin relaxivities, colloidal stability, and biocompatibility of nanoparticle magnetic resonance imaging (MRI) contrast agents depend on surface-coating ligands. In this study, hydrophilic and biocompatible polyethylenimines (PEIs) of different sizes (Mn = 1200 and 60,000 amu) were used as surface-coating ligands for ultrasmall holmium...

Owing to a higher demand for glucosamine (GlcN) in metabolic processes in tumor cells than in normal cells (i.e., GlcN effects), tumor imaging in magnetic resonance imaging (MRI) can be highly improved using GlcN-conjugated MRI contrast agents. Here, GlcN was conjugated with polyacrylic acid (PAA)-coated ultrasmall gadolinium oxide nanoparticles (U...

Surface-coating polymers contribute to nanoparticle-based magnetic resonance imaging (MRI) contrast agents because they can affect the relaxometric properties of the nanoparticles. In this study, polyaspartic acid (PASA)-coated ultrasmall Gd2O3 nanoparticles with an average particle diameter of 2.0 nm were synthesized using the one-pot polyol metho...

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...

Apoferritin (APO) with a diameter of ~12 nm is a naturally occurring protein assembly in living organisms. APO is made of 24 protein subunits that form a nanocage with an inner diameter of ~8 nm. Thus far, the loading of only a few nanoparticles inside the nanocage of APO has been reported. In this study, the mass loading of D-glucuronic acid (GA)-...

Polyacrylic acid (PAA)-coated lanthanide oxide (Ln2O3) nanoparticles (NPs) (Ln = Tb and Ho) with high colloidal stability and good biocompatibility were synthesized, characterized, and investigated as a new class of negative (T2) magnetic resonance imaging (MRI) contrast agents at high MR fields. Their r2 values were appreciable at a 3.0 T MR field...

Ultrasmall nanoparticles are potential candidates for application as high-performance imaging agents. Herein, we present the synthesis and characterization of folic acid (FA)-conjugated polyacrylic acid (PAA)-coated MnO nanoparticles with an average particle diameter of 2.7 nm. FA conferred cancer-targeting ability, while PAA conferred good colloid...

The water proton spin relaxivity, colloidal stability, and biocompatibility of nanoparticle-based magnetic resonance imaging (MRI) contrast agents depend on the surface-coating ligands. Here, poly(acrylic acid-co-maleic acid) (PAAMA) (Mw = ~3000 amu) is explored as a surface-coating ligand of ultrasmall gadolinium oxide (Gd2O3) nanoparticles. Owing...

Magnetic nanobeads can be applied to the magnetic separation of nucleic acids which can be used for diagnosing infectious and genetic diseases of patients. In this study, core-shell structured silica-coated iron oxide (Fe3O4@SiO2) nanobeads with a core size distribution of 40–50 nm and a shell thickness of ∼ 10 nm were synthesized and applied to th...

Nanoparticles are considered potential candidates for a new class of magnetic resonance imaging (MRI) contrast agents. Negative MRI contrast agents require high magnetic moments. However, if nanoparticles can exclusively induce transverse water proton spin relaxation with negligible induction of longitudinal water proton spin relaxation, they may p...

Until now, there have been limited studies on T2 magnetic resonance imaging (MRI) contrast agents (CAs) using paramagnetic nanoparticles (NPs). In this study, ultrafine dysprosium oxide (Dy2O3) NPs were synthesized as a T2 MRI CA. To obtain high biocompatibility and colloidal stability in aqueous medium for in vivo applications, they were grafted w...

The study of ultra-small paramagnetic gadolinium oxide (Gd 2 O 3) nanoparticles (NPs) as in vivo positive (T 1) magnetic resonance imaging (MRI) contrast agents is one of the most attractive fields in nanomedicine. The performance of the Gd 2 O 3 NP imaging agents depends on the surface-coating materials. In this study, poly(methyl vinyl ether-alt-...

Gadolinium neutron capture therapy (GdNCT) is considered as a new promising cancer therapeutic technique. Nevertheless, limited GdNCT applications have been reported so far. In this study, surface-modified ultrasmall gadolinium oxide nanoparticles (UGNPs) with cancer-targeting ability (davg = 1.8 nm) were for the first time applied to the in vivo G...

Ultrasmall Bi2O3 nanoparticles (davg = 1.5 nm) coated with biocompatible and hydrophilic D-glucuronic acid were prepared for the first time through a simple one-step polyol process and their potential as CT contrast agents were investigated by measuring their X-ray attenuation properties. Their observed X-ray attenuation power was stronger than tha...

Carbon may be an ideal surface-coating material on nanoparticles (NPs) for biomedical applications because carbon is biocompatible, nearly chemically inert, and photoluminescent in the visible region. In this research, the carbon-coated ultrasmall gadolinium oxide (Gd2O3 @C) core-shell NPs (core = Gd2O3; shell = carbon) were synthesized in aqueous...

[This corrects the article DOI: 10.1371/journal.pone.0211826.].

Many of the lanthanide‐based nanoparticles are valuable in magnetic resonance imaging (MRI) because they have excellent magnetic properties that make them suitable for MRI contrast agents, while some of them have additional optical properties and thus can serve as fluorescence imaging (FI) agents as well. Herein, we synthesized d‐glucuronic acid‐co...

Ultrasmall heavy metal oxide nanoparticles are potential candidate materials for X-ray computed tomography (CT) contrast agents because they possess high X-ray attenuation powers owing to high X-ray attenuation coefficients of heavy metal atoms and high density of heavy metal atoms per nanoparticle. In this study, five kinds of poly- acrylic acid (...

In this study, we report the synthesis and characterization of 3,5 Diiodo -L-tyrosine (DLT)-coated gadolinium oxide (Gd2O3) nano- particles. The bonding status of DLT-coated Gd2O3 nanoparticles (DLT-NPs) were confirmed by Fourier transform infrared (FT-IR) absorption spectra and thermogravimetric analysis (TGA). The surface coating amount was estim...

Absence of geomagnetic orientation in starved men without food association. The starved men were tested after no association under different light conditions or a particular magnetic field. (A)–(D) An unremarkable magnetic north orientation under the blindfold (A), light (400–800 nm) (B), light (500–800 nm) (C), and the inversion of vertical compon...

Spectra of the lights used in the experiments. (A)–(C) Spectrums of light-emitting diode lights that were filtered by nothing (A), filter glasses (> 400 nm) (B), and filter glasses (> 500 nm) (C). Dashed lines denote the cutoff points of the filters. (PDF)

Absence of geomagnetic orientation in food-associated humans without starvation. (A) and (B) No significant geomagnetic orientation in the unstarved men (A) and women (B), tested after the food association. (A) α = 109.4°, r = 0.15, P = 0.62 (V test), P = 0.65 (Rayleigh test), n = 20. (B) α = 89.4°, r = 0.08, P = 0.50 (V test), P = 0.87 (Rayleigh t...

Nutrient facts for chocolate chips used in experiments. a Twenty chocolate chips were provided to a subject in an experiment. b The % Daily Value means how much a nutrient in a serving food contributes to a daily diet. 2,600 and 2,100 calories a day are used for general nutrition advice for South Korean men and women (19–29 years old), respectively...

Ultrasmall heavy metal-oxide nanoparticles can be utilized for highly enhancing contrasts in computed tomography (CT). In this study, ultrasmall Yb2O3 nanoparticles coated with biocompatible and hydrophilic D-glucuronic acid were for the first time prepared through a simple one-step polyol process, and their X-ray attenuation properties were invest...

A polyol method is extremely useful for preparimg metal-containing nanoparticles coated with hydrophilic and biocompatible ligands for biomedical applications. In this study, D-glucuronic acid-coated BiOI nanoparticles were prepared in one-pot using this method. The particle diameter was controlled by varying the solvent volume such that the partic...

Monodisperse and ultrasmall gadolinium oxide (Gd2O3) nanoparticle colloids (davg = 1.5 nm) (nanoparticle colloid = nanoparticle coated with hydrophilic ligand) were synthesized and their performance as a multifunctional tumor theragnostic agent was investigated. The aqueous ultrasmall nanoparticle colloidal suspension was stable and non-toxic owing...

In this study, amorphous carbon nanoparticles (CNPs) with an average diameter of 2.2 nm were synthesized by reducing dextrose (C6H12O6) with sodium hydroxide in an aqueous medium. The amorphous CNPs formed stable colloidal suspensions in water owing to the presence of hydrophilic functional groups on the nanoparticle surfaces. The amorphous CNPs ex...

The tumor targeting is essential in order to use excellent theranostic properties of gadolinium oxide (Gd2O3) nanoparticles (GNPs) as high‐performance positive magnetic resonance imaging (T1 MRI) contrast agents, X‐ray computed tomography (CT) contrast agents, and gadolinium neutron capture therapy (GdNCT) agents. Among these applications, the tumo...

We prepared gadolinium oxide (Gd2O3) nanoparticles (GNPs) coated with a trans-activator of transcription (TAT) peptide with cell-penetrating ability (i.e., TAT-GNPs) through one-pot process. We characterized the particle diameter, surface-coating structure, water proton relaxivities, and in vitro cellular toxicities of the TAT-GNPs. We measured in...

For use as positive (T1) magnetic resonance imaging contrast agents (MRI-CAs), gadolinium oxide (Gd2O3) nanoparticle colloids (i.e. nanoparticles coated with hydrophilic ligands) should be stable, non-toxic, and ultrasmall in particle diameter for renal excretion. In addition, they should have a high longitudinal water proton relaxivity (r1) and r2...

Ultrasmall Gd2O3 nanoparticles can potentially be used as a positive magnetic resonance imaging (MRI) contrast agent owing to their high content of Gd(III), which exhibits the highest spin magnetic moment of all elements due to its seven unpaired 4f electrons. Herein, the above nanoparticles (average diameter = 2.0 nm) were coated with hydrophilic...

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 assynthesized D-glucuronic acid-coated nanoparticles were amorphous owing to ultrasmall particle diameters (davg = 2�0 nm), whereas orthorhombic Cr2O3 nanoparticles...

Nanoparticles are very important in biomedical imaging because their imaging properties are superior to those of small molecules. They can be further functionalized for multimodal imaging through surface modification. In this study, we synthesized dye-coated ultrasmall gadolinium oxide nanoparticles [dye = fluorescein and fluorescein isothiocyanate...

The Earth's geomagnetic field (GMF) is known to act as a sensory cue for magnetoreceptive animals such as birds, sea turtles, and butterflies in long-distance migration, as well as in flies, cockroaches, and cattle in short-distance movement or body alignment. Despite a wealth of information, the way that GMF components are used and the functional...

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 (r 1) of 12.3 s−1mM−1 with r 2/r 1 = 1.1, corresponding to an ideal condition for T 1 MRI contrast agent. We attribute this to reduced magnetizatio...

Background Appropriate vertical movement is critical for the survival of flying animals. Although negative geotaxis (moving away from Earth) driven by gravity has been extensively studied, much less is understood concerning a static regulatory mechanism for inducing positive geotaxis (moving toward Earth). Results Using Drosophila melanogaster as...

Iron (Fe)-based nanoparticles are extremely valuable in biomedical applications owing to their low toxicity and high magnetization values at room temperature. In this study, we synthesized nearly monodisperse iron oxide (Fe3O4) and Fe@Fe3O4 (core: Fe, shell: Fe3O4) nanoparticles in aqueous medium under argon flow and then, coated them with various...

Ultrasmall gadolinium oxide (Gd2O3) nanoparticles coated with dextran ( r=1500 amu) were prepared through one-pot synthesis and their potential to act as a T1 MRI contrast agent was investigated. The dextran-coated ultrasmall Gd2O3 nanoparticles were highly water-dispersible, with an average particle diameter of 1.5 nm and an average hydrodynamic d...

Geotaxis and phototaxis are movements in response to gravity and light, respectively, and are commonly observed in nature. The interactions between these two types of movement have been shown to confer ecological advantages to many taxa. Although several studies have been conducted on phototaxis and geotaxis in various organisms, reports on the int...

The relaxometric properties of ultrasmall Gd2O3 nanoparticles coated with various ligands were investigated. These ligands include small diacids with hydrophobic chains, namely, succinic acid (Mw = 118.09 amu), glutaric acid (Mw = 132.12 amu), and terephthalic acid (Mw = 166.13 amu), and large polyethylenimines (PEIs) with hydrophilic chains, name...

Imaging agents are essential in diagnosing malignant tumors. Various elements are currently used as imaging agents in various chemical forms; gadolinium for magnetic resonance imaging (MRI), iodine for X-ray computed tomography (CT), and radioisotopes with short half-lives for positron emission tomography (PET). Among them, gadolinium is a special...

Water-soluble and biocompatible D-glucuronic acid coated Na2WO4 and BaCO3 nanoparticles were synthesized for the first time to be used as x-ray computed tomography (CT) contrast agents. Their average particle diameters were 3.2 ±0.1 and 2.8 ±0.1 nm for D-glucuronic acid coated Na2WO4 and BaCO3 nanoparticles, respectively. All the nanoparticles exhi...

A new type of dual-mode T1 and T2 magnetic resonance imaging (MRI) contrast agent based on mixed lanthanide oxide nanoparticles was synthesized. Gd3+ (8S7/2) plays an important role in T1 MRI contrast agents because of its large electron spin magnetic moment resulting from its seven unpaired 4f-electrons, and Dy3+ (6H15/2) has the potential to be u...

Surface coating of nanoparticles with ligands is essential in magnetic resonance imaging (MRI) because of solubility in water and biocompatibility. In this study, five organic molecules were used for surface coating of ultrasmall gadolinium-oxide (Gd2O3) nanoparticles (d avg = 2.0 nm). All of the samples showed large longitudinal (r1) and transvers...

An ideal T 1 MRI contrast agent should have a large r 1 value and r 2 /r 1 ratio, which is close to 1. In this study, a new approach to accomplish this is presented using the mixed Cu(II)/Gd(III) oxide nanoparticle. The D-glucuronic acid-coated Cu(II)/Gd(III) oxide nanoparticle showed r 1 = 13.78 mM −1 s −1 and r 2 = 14.48 mM −1 s −1 (r 2 /r 1 = 1....

Gadolinium (Gd) is a unique and powerful element in chemistry and biomedicine which can be applied simultaneously to magnetic resonance imaging (MRI), X-ray computed tomography (CT), and neutron capture therapy for cancers. This multifunctionality can be maximized using gadolinium oxide (Gd2O3) nanoparticles (GNPs) because of the large amount of Gd...

The dependence of longitudinal (r1) and transverse (r2) water proton relaxivities of ultrasmall gadolinium oxide (Gd2O3) nanoparticles on the surface coating ligand-size was investigated. Both r1 and r2 values decreased with increasing ligand-size. We attributed this to the ligand-size effect. In addition the effectiveness of d-glucuronic acid-coat...

Ultrasmall lanthanide oxide nanoparticles are promising materials as new magnetic resonance imaging (MRI) contrast agents because of their appreciable longitudinal (r1) or transverse (r2) water proton relaxivities at ultrasmall particle diameters. Two systems of d-glucuronic acid coated ultrasmall Ln/Mn (Ln = Gd and Dy) oxide nanoparticles with an...

There is no doubt that the molecular imaging is an extremely important technique in diagnosing diseases. Dual imaging is emerging as a step forward in molecular imaging technique because it can provide us with more information useful for diagnosing diseases than single imaging. Therefore, diverse dual imaging modalities should be developed. Molecul...

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 sh...

Purpose: Professional and public concern about the potential adverse effects of man-made electromagnetic fields (EMF) on the human body has dramatically expanded in recent years. Despite numerous attempts to investigate this issue, the long-standing challenge of reproducibility surrounding alternating EMF effects on human health remains unresolved...

To date, only a few nanosystems have been investigated as T1 MRI-CT dual contrast agents. The T1 MRI-CT dual functionality of a material depends on its longitudinal water-proton relaxivity (r1) and X-ray absorption strength. We explored Gd(IO3)3·2H2O nanomaterial because Gd is the most powerful element for T1 MRI contrast agents, and both Gd and I...

Potentials of hydrophilic and biocompatible ligand coated gadolinium oxide nanoparticles as multimodal imaging agents, drug carriers, and therapeutic agents are reviewed. First of all, they can be used as advanced T1 magnetic resonance imaging (MRI) contrast agents because they have r1 larger than those of Gd(III)-chelates due to a high density of...