Min Goo Hur

Design, synthesis, and anti-influenza viral activities of 1,3-diarylprop-2-en-1-ones: a novel class of neuraminidase inhibitors.

A series of 1,3-diarylprop-2-en-1-one derivatives 3a-v have been synthesized and evaluated for their ability to inhibit neuraminidase (NA). Among the prepared compounds, the less lipophilic derivative 3k showed the most potent in vitro inhibitory activity against NA with an IC50 value of 1.5 ∝M.

Synthesis and characterization of 68Ga labeled Fe3O4 nanoparticles for positron emission tomography (PET) and magnetic resonance imaging (MRI)

We designed a 68Ga labeled Fe3O4 nano-biocomposite for dual applications as diagnostic imaging agent in positron emission tomography (PET)/magnetic resonance imaging (MRI). The nano-biocomposites (68GaNHFCNP) were fabricated via surface modified iron oxide nanoparticles and NOTA as bi-functional chelating agent with 68Ga isotopes from 68Ge/68Ga generator. The structure and morphological properties of nano-biocomposite was characterized by XRD, TEM and IR analysis. 68GaNHFCNPs exhibits very low cytotoxicity and high cellular uptake upon SK-BR-3 and CT-26 cell lines. The advantages of high biocompatibility, magnetism and cell uptake make this composite promising as a potential probe of PET/MRI for effective detection of cancer.

Fluorescent 2-styrylpyridazin-3(2H)-one derivatives as probes targeting amyloid-beta plaques in Alzheimer's disease.

Amyloid plaques, which are primarily composed of aggregated amyloid-beta (Aβ) peptide, are the neuropathological hallmarks of Alzheimers disease (AD). Fluorescent markers containing 2-styrylpyridazin-3(2H)-ones were developed to detect intracellular aggregated Aβ peptides. Nine compounds exhibited a greater than 10-fold increase of in emission spectra before and after mixing with Aβ aggregates compared with before mixing. Among these compounds, compound 9n exhibited the highest affinity for Aβ aggregates (K(d)=1.84 μM) and selectively stained both aggregated intracellular Aβ and Aβ plaques in the transgenic AD model mice (APP/PS1). These preliminary results indicate that 2-styrylpyridazin-3(2H)-one derivatives are promising alternative fluorescence imaging agent for the study of AD.

Discovery of boronic acid-based fluorescent probes targeting amyloid-beta plaques in Alzheimer’s disease

A boronic acid-based fluorescent probe was developed for diagnosis of amyloid-β (Aβ) plaques from Alzheimers disease (AD). Probe 4c, which included boronic acid as a functional group, exhibited a significant increase (64.37-fold, FAβ/F0) in fluorescence intensity as a response to Aβ aggregates, with a blue shift (105nm) in the maximum emission wavelength. We found that boronic acid as a functional group improved the binding affinity (KD value=0.79±0.05μM for 4c) for Aβ aggregates and confirmed that 4c selectively stained Aβ plaques in brain sections from APP/PS1 mice. Ex vivo fluorescence imaging using mice (normal and APP/PS1) also revealed that 4c was able to penetrate the blood-brain barrier (BBB) and to stain Aβ plaques in the brain. From these results, we believe that 4c will be useful as a fluorescent probe in preclinical research related to AD. Furthermore, we believe that our results with boronic acid also provide valuable information for the development of a probe for Aβ plaques.

Acid resistant zirconium phosphate for the long term application of 68 Ge/ 68 Ga generator system

The 68Ge/68Ga generator system is an excellent source for producing ready-to-use Ga-68 in clinical Positron Emission Tomography (PET) applications. The column adsorbent is the key component for the 68Ge/68Ga generator system. Therefore, several studies have been conducted to identify column materials with a stable and superior elution yield in an acidic eluent (0.1 N HCl solution). In this study, four different zirconium phosphates were synthesized with a particle size of 200-800nm, pore-size of 55∼190Å and surface area of 0.72-268m2g-1. Synthesized and studied amorphous zirconium phosphate (ZrP-1) exhibited excellent acid resistant properties for the 0.1 N HCl eluent and a large surface area of 268m2g-1. Amorphous ZrP-1 showed a good Ga-68 elution yield of 74% in 0.1 N HCl eluent accompanying extraordinary low breakthrough of Ge-68 (0.007%).

Test Production of Ti-44 using RFT-30 Cyclotron

RFT-30 30 MeV cyclotron has been developed for the production of radioisotopes and their applications. Fluorine-18, which is a widely-used positron emitter, has been produced regularly since 2015. In addition, research on the production of generator radioisotopes has been performed using this cyclotron. A generator means a device used to extract the positron-emitting daughter radioisotope from a source of the decaying parent radioisotope such as Ti and Ge. In this research, Sc targets were proton-irradiated in order to produce Ti. Gamma spectra of irradiated targets were measured to confirm the production of Ti-44.

In-house development of an optimized synthetic module for routine [11C]acetate production.

[11C]Acetate, a radiotracer for PET imaging, is a promising radiopharmaceutical for overcoming the limitation of 2-deoxy-2-[18F]fluoro-D-glucose in a number of cancers. Here, the optimized automatic synthesis of [11C]acetate using an in-house-developed module under different conditions has been reported for routine production. [11C]CO2 was produced in a 16.4 MeV PETtrace cyclotron, and methyl magnesium chloride was used for synthesis. For product purification, ion-exchange solid-phase extraction cartridges were used, connected in series. High-performance liquid chromatography and gas chromatography were used to measure radiochemical and chemical purity. The Limulus amebocyte lysate test and the fluid thioglycollate medium test were performed for quality control of [11C]acetate. The total reaction time of [11C]acetate was within 15 min, and the overall decay-corrected radiochemical yield was 84.33±8.85%. Radiochemical purity was greater than 98% when evaluated on an analytical high-performance liquid chromatography system. No endotoxins or anaerobic bacteria were seen on quality control checks. Optimized production of [11C]acetate was achieved by the in-house module. Radiochemical and biological properties of the [11C]acetate produced were appropriate for clinical PET study.

Effect of liquid Ga on metal surfaces: characterization of morphology and chemical composition of metals heated in liquid Ga

This study investigates the effect of liquid gallium (Ga) on metal foils made of titanium (Ti), niobium (Nb), and molybdenum (Mo). The Ti, Nb, and Mo foils were heated in liquid Ga at 120°C for a maximum of two weeks. After heating, the changes in the morphology and the chemical composition of the metal foils were analyzed by using a field emission scanning electron microscope, energy-dispersive X-ray spectrometer, X-ray diffractometer, and X-ray photoelectron spectrometer. The results of the analysis indicated that the Nb foil showed the minimum adhesion of liquid Ga to the surface while the maximum amount of liquid Ga was observed to adhere to the Ti foil. In addition, the Nb foil was oxidized and the Mo foil was reduced during the heating process. Considering these effects, we conclude that Mo may be used as an alternative encapsulation material for Ga in addition to Nb, which is used as the conventional encapsulation material, due to its chemical resistance against oxidation in hot liquid Ga.