• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.132.1-132.1
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• 2014

Fluorescent-magnetic nanoclusters were synthesized for biomedical applications. The nanoclusters consisted of superparamagnetic core-nanoclusters, highly fluorescent shell of nanocrystals, and lipid A. Magnetic cores were used for both magnetic resonance imaging (MRI) and cell separation. Fluorescent shell was used for optical imaging. The lipid-A-loaded nanoclusters were up-taken by dendritic cells via phagocytosis, which successfully activated dendritic cells. The dendritic cells were migrated to lymph nodes and spleen of mice. The results showed that our novel nanoclusters can play a role as an efficient optical and magnetic imaging, a cell separating and a pathogen mimetic agent at the same time. Additionally, synthesis of wavelength conversion nanowires will be discussed, which may be used as an optical nanoprobe in biological studies.

• Macromolecular Research
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• 제12권6호
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• pp.604-607
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• 2004

We report an important and useful method for preparing ${\omega}-sulfonated$ polystyrene-stabilized cadmium sulfide (CdS) nanoclusters. The ${\omega}-sulfonated$ polystyrene $(M_n\;=\;5000\;g/mol)$ was prepared successfully through chain-end sulfonation of poly(styryl)lithium using 1,3-propanesultone; the resulting polymer was used successfully as a polymeric stabilizing agent for the preparation of semiconductor CdS nanoclusters by reduction of cadmium acetate in a mixture of toluene and methanol (9:1, v/v). The nanoclusters that formed were characterized by a combination of transmission electron microscopy, X-ray diffraction, and UVN is spectroscopic analysis. The ${\omega}-sulfonated$ polystyrene-stabilized CdS nanoclusters synthesized in this study exhibited the cubic phase (zinc-blende phase) structure in the range of 2-8 nm.

• 한국전기전자재료학회논문지
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• 제29권11호
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• pp.685-689
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• 2016

Synthesis of the fluorescent Au nanoclusters is reported. The Au nanoclusters were synthesized via reduction of gold ions in reverse micelles with mild reducing agents. The Au nanoclusters show a bright red emission at 640 nm. The fluorescent Au nanoclusters attract great interest for sensor, electronic device and bio-imaging applications because of ultra-small size, high chemical stablity and bright emission. We believe that the fluorescent Au nanoclusters can have optoelectronic applications such as optical down conversion phosphors.

• Advances in nano research
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• 제1권3호
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• pp.125-131
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• 2013

This study is aimed to calculate the radiative lifetime of Wannier-Mott excitons in nanoclusters of a narrow-bandgap semiconductor embedded in a wide-bandgap one. The nanocluster linear dimensions are assumed to be much larger than the radius of the exciton so that the latter is not destructed by the confinement potential as it takes place in small quantum dots. The calculations were carried out for an example of InAs nanoclusters put into the GaAs matrix. It is shown that the radiative lifetime of Wannier-Mott excitons in such clusters increases with the decrease of the cluster dimensions, this tendency being more pronounced at low temperatures. So, the creation of excitons in nanoclusters of a narrow-bandgap material embedded in a wide-bandgap one can be used to significantly prolong their radiative lifetime in comparison with that of excitons in a bulk semiconductor.

• Current Photovoltaic Research
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• 제7권2호
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• pp.29-32
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• 2019

Large band gap attenuation of CdS nanoclusters in hybrid sol gel matrix comprised of 3-(trimethoxysilyl)propyl methacrylate (TMSPM), 15 wt. % zirconium, and various amounts of cadmium acetate was observed after $H_2S$ exposure. Hybrid sol gel matrixes were prepared by hydrolysis and condensation reactions. The sol gels contained with various amount of cadmium acetate were spin coated to glass substrates and exposed to $H_2S$ gas. The UV-visible absorption peaks were shifted toward blue with increasing the amount of CdS nanoclusters and were shifted to the red after thermal process. Significant amount of -OH absorption peaks were reduced after thermal process. Strong room temperature photoluminescence (PL) of CdS nanoclusters was observed after exposing to $H_2S$ gas. The PL intensity increased for several minutes and slowly decreased thereafter. The luminescence peaks were continuously shifted toward blue as the time passed. Extraordinary Stokes shift (approximately 160 nm) was observed.

• 한국재료학회지
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• 제22권7호
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• pp.329-334
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• 2012

Two types of nanoclusters, termed Cluster (1) and Cluster (2) here, both play an important role in the age-hardening behavior in Al-Mg-Si alloys. Small amounts of additions of Cu and Ag affect the formation of nanoclusters. Two exothermic peaks were clearly detected in differential scanning calorimetry(DSC) curves by means of peak separation by the Gaussian method in the base, Cu-added, Ag-added and Cu-Ag-added Al-Mg-Si alloys. The formation of nanoclusters in the initial stage of natural aging was suppressed in the Ag-added and Cu-Ag-added alloys, while the formation of nanoclusters was enhanced at an aging time longer than 259.2 ks(3 days) of natural aging with the addition Cu and Ag. The formation of nanoclusters while aging at $100^{\circ}C$ was accelerated in the Cu-added, Ag-added and Cu-Ag-added alloys due to the attractive interaction between the Cu and Ag atoms and the Mg atoms. The influence of additions of Cu and Ag on the clustering behavior during low-temperature aging was well characterized based on the interaction energies among solute atoms and on vacancies derived from the first-principle calculation of the full-potential Korrinaga-Kohn-Rostoker(FPKKR)-Green function method. The effects of low Cu and Ag additions on the formation of nanoclusters were also discussed based on the age-hardening phenomena.

• 대한화학회지
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• 제65권5호
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• pp.397-400
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• 2021

• Advances in nano research
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• 제2권4호
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• pp.187-198
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• 2014

Magnetite nanoparticles (MNPs) of different sizes were synthesized by solvothermal process maintaining their stoichiometric composition and unique structural phase. Utilizing hydrated ferric (III) chloride as unique iron precursor, it was possible to synthesize sub-micrometric magnetite clusters of sizes in between 208 and 381 nm in controlled manner by controlling the concentration of sodium acetate in the reaction mixture. The sub-micrometer size nanoclusters consist of nanometric primary particles of 19 - 26.3 nm average size. The concentration of sodium acetate in reaction solution seen to control the final size of primary MNPs, and hence the size of sub-micrometric magnetite nanoclusters. All the samples revealed their superparamagnetic behavior with saturation magnetization ($M_s$) values in between 74.3 and 77.4 emu/g. $M_s$. The coercivity of the nanoclusters depends both on the size of the primary particles and impurity present in them. The mechanisms of formation and size control of the MNPs have been discussed.

• 한국응용과학기술학회지
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• 제31권3호
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• pp.525-533
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• 2014

금속이 도핑 된 산화아연 나노클러스터를 합성하기 위해 마이크로웨이브를 이용한 폴리올 공정은 빠르고 경제적인 합성 방법이다. 디에틸렌글리콜은 높은 분극률과 마이크로파의 흡수 능력이 뛰어나며, 높은 온도상승 비율과 반응시간을 짧게 해준다. 본 연구에서는 금속이 도핑 된 산화아연 나노클러스터를 합성하기 위해서 첨가되는 seed의 부피비를 다르게 하여 얻었으며, 전구체로는 아세트산 아연 2수화물, 도핑 금속은 아세트산 금속 염을 그리고 용매로서 디에틸렌글리콜을 사용하였다. 금속이 도핑된 산화아연 클러스터는 FE-SEM, XRD, Raman, PSA로 특성을 확인하였다.

• 한국분말재료학회지
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• 제30권4호
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• pp.297-304
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• 2023

Iron oxide (Fe₂O₃) nanoclusters exhibit significant potential in the biomedical and pharmaceutical fields due to their strong magnetic properties, stability in solutions, and compatibility with living systems. They excel in magnetic separation processes, displaying high responsiveness to external magnetic fields. In contrast to conventional Fe2O3 nanoparticles that can aggregate in aqueous solutions due to their ferrimagnetic properties, these nanoclusters, composed of multiple nanoparticles, maintain their magnetic traits even when scaled to hundreds of nanometers. In this study, we develop a simple method using solvothermal synthesis to precisely control the size of nanoclusters. By adjusting precursor materials and reducing agents, we successfully control the particle sizes within the range of 90 to 420 nm. Our study not only enhances the understanding of nanocluster creation but also offers ways to improve their properties for applications such as magnetic separation. This is supported by our experimental results highlighting their size-dependent magnetic response in water. This study has the potential to advance both the knowledge and practical utilization of Fe₂O₃ nanoclusters in various applications.