• Transactions of the Korean hydrogen and new energy society
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• v.34 no.2
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• pp.169-177
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• 2023

Phase stability diagrams were constructed for magnesium alanate (Mg(AlH₄)₂) nanoparticles to investigate the reversible hydrogen storage reaction by using density functional theory. Our findings indicate that bulk Mg(AlH₄)₂ shows favorable hydrogen release, but unfavorable hydrogen uptake (adsorption) reactions. However, for Mg(AlH₄)₂ nanoparticles, it was observed that hydrogen release and recharge can be achieved by controlling the particle size and temperature. Furthermore, by predicting the decomposition phase diagram of Mg(AlH₄)₂ nanoparticles with varying hydrogen partial pressure, it was discovered that reversible dehydrogenation reactions can occur even in relatively large nanoparticles by controlling the hydrogen partial pressure.

• Korean Journal of Materials Research
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• v.33 no.1
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• pp.1-7
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• 2023

The physical and antibacterial properties of ophthalmic lenses fabricated by copolymerization with hydrogel monomers using two types of graphene were measured, and their usability as contact lens materials was analyzed. For polymerization, silicone monomers, including SID-OH, 3-(methacryloxy)propyl tris(trimethylsiloxy)silane, and decamethylcyclopentasiloxane, were used, and N,N-dimethylacetamide, ethylene glycol dimethacrylate as a crosslinking agent, and azobisisobutyronitrile as an initiator were added. Also, graphene oxide nanoparticle (GON) and graphene nanoplate (GNP) were used as an additive, and the physical properties of the lenses fabricated after copolymerization were evaluated. The fabricated lenses satisfied the basic physical properties of general hydrogel contact lenses and showed the characteristics of lenses with high water content, and the disadvantage of very weak durability, due to low tensile strength. However, it was confirmed that the tensile strength and antibacterial properties were greatly improved by adding GON and GNP. With GON, the oxygen permeability and refractive index of the fabricated lenses were slightly improved. Therefore, it was determined that the graphene materials used in this study can be used in various ways as a contact lens material.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1539-1542
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• 2005

Self-assembled monolayers (SAMs) formed by the adsorption of alkanethiols, $HS(CH_2)_nX$, where X is an organic functional group, onto gold surfaces have attracted widespread interest as templates for the fabrication of molecular and biomolecular microstructures. Previously photopatterning has been thought of as being restricted to the micron scale, because of the wellknown diffraction limit. So, we have explored a novel approach to nanofabrication by utilizing a femtosecond laser coupled to a near-field scanning optical microscope (NSOM).

• BMB Reports
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• v.44 no.2
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• pp.77-86
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• 2011

Over the years, nanostructures have been developed to enable to support enzyme usability to obtain highly selective and efficient biocatalysts for catalyzing processes under various conditions. This review summarizes recent developments in the nanostructures for enzyme supporters, typically those formed with various inorganic materials. To improve enzyme attachment, the surface of nanomaterials is properly modified to express specific functional groups. Various materials and nanostructures can be applied to improve both enzyme activity and stability. The merits of the incorporation of enzymes in inorganic nanomaterials and unprecedented opportunities for enhanced enzyme properties are discussed. Finally, the limitations encountered with nanomaterial-based enzyme immobilization are discussed together with the future prospects of such systems.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.69-75
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• 2008

Tautomerism of pyrimidine base cytosine has been comparatively examined on nanoparticle and roughened plate surfaces of silver, gold, and copper by surface-enhanced Raman scattering (SERS). The SERS spectrum was found to be different depending on the metals and their substrate conditions suggesting the dissimilar population of various tautomers of cytosine on the surfaces. The ab initio calculations were performed at the levels of B3LYP, HF, and MP2 levels of theory with the LanL2DZ basis set to estimate the energetic stability of the tautomers with the metal complexes as well as the gas phase state. The amino group and N3-coordinated tautomer was predicted to be more favorable for bonding to Au, whereas the hydroxyl and N1-coordinated zwitter ionic form is most stable with Ag and Cu as a bidentate form from the DFT calculation. The binding energy with the Ag atom is calculated to be smaller than those with the Au and Cu atoms in line with the temperature-dependent SERS spectra of cytosine.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1048-1051
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• 2003

주사탐침현미경 (Scanning Probe Microsope, SPM)을 이용하여 직접 패터닝을 함으로써 hexanedithiol 분자의 임의 패턴을 금 표면에 형성하였다. 또한, hexanedithiol 분자는 양단에 thiol 그룹이 존재하여 금과 안정화 화학결합을 이룰 수 있으므로, 금 표면과결합을 이루고 있지 않는 상단의 thiol 그룹에 금 나노 입자를 고정함으로써 나노입자의 패턴을 제작하였다. SPM을 이용한 직접 패터닝 방법은 분자활성을 유지한 채로 임의 패턴을 수십 nm의 선폭으로 구현하는 것이 가능하므로, 나노입자 배열뿐만 아니라, 생화학물질의 패터닝을 통한 바이오 기술연구, 레지스트용 분자 패터닝과 시각 및 흡착 등의 계속적인 공정을 통한 다양한 나노구조 제작 등에 폭넓게 활용될 수 있다.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.9
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• pp.4237-4240
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• 2016

Drugs processed using nanobiotechnology may be more biocompatible, with sustainable and stabilised release or action. L-asparaginase produced from fungi has many advantages for treatment of lymphocytic leukemia with lesser side effect. In the present work, maghemite nanobiocomposites of fungal asparaginase were produced using glutaraldehyde-pretreated colloidal magnetic nanoparticles. Formation of nanobiocomposites was observed using laser light scattering and confirmed by UV-visible spectrophotometry with the absorption peak at 497 nm. The specific asparaginase activity was increased from 320 U/mg with crude asparaginase to 481.5 U/mg. FTIR analysis confirmed that primary amines are the functional groups involved in binding of asparaginase on magnetic nanoparticles. The average size of the produced nanobiocomposite was found in the range of 30 nm to 40 nm using histogram analysis. The magnetic nanobiocomposite of asparaginase synthesised using glutaraldehyde showed 90.75% cytotoxicity against human colon adenocarcinoma cell lines. Hence it can be used as an active anticancer drug with an augmented level of bioavailability.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.475-476
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• 2006

Self-assembled monolayers (SAMs) formed by the adsorption of alkanethiols, HS(CH2)nX, where X is an organic functional group, onto gold surfaces have attracted widespread interest as templates for the fabrication of molecular and biomolecular microstructures. Previously photopatterning has been thought of as being restricted to the micron scale, because of the well-known diffraction limit. So, we have explored a novel approach to nanofabrication by utilizing a femtosecond laser.

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.125-131
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• 2017

We report organically functionalized Ag nanoparticles spontaneously form two-dimensional (2D) novel superstructures at the air-water interface. Analysis of the superstructures suggests that the 2D assembly of Ag nanoparticles originates from a subtle interplay between characteristic inter-particle interactions that can be readily controlled by changing the sizes of nanoparticle metal core and surfactants. Such structures have potential uses in nanostructured functional materials, catalysis, and device applications.

• Carbon letters
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• v.13 no.1
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• pp.29-33
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• 2012

A novel strategy for the simultaneous reduction and functionalization of graphene oxide (G-O) was developed using polyallylamine hydrochloride (PAAH) as a multi-functional agent. The G-O functionalization by PAAH was carried out under basic conditions to catalyze the epoxide ring opening reaction of G-O with abundant amine groups of PAAH. We found that G-O was not only functionalized with PAAH but also reduced under the reaction condition. Moreover, the synthesized PAAH-functionalized G-O sheets were soluble in water and applicable to the synthesis of nanocomposites with gold nanoparticles.