• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1883-1886
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• 2013

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.971-974
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• 2013

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1894-1896
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• 2006

• Macromolecular Research
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• v.15 no.7
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• pp.688-692
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• 2007

The hydrogen-bonding induced alternating multilayer thin films of dendrimers and block copolymer micelles were demonstrated. The block copolymer micelles derived from amphiphilic poly(2-ethyl-2-oxazoline)block-$poly({\varepsilon}-carprolactone)$ (PEtOz-PCL) in aqueous phase have a core-shell structure with a mean hydrodynamic diameter of 26 nm. The hydrogen bonding between the PEtOz outer shell of micelle and the carboxyl unit of poly(amidoamine) dendrimer of generation 4.5 (PAMAM-4.5G) at pH 3 was utilized as a driving force for the layerby-layer alternating deposition. The multilayer thin film was fabricated on the poly(methyl methacrylate) (PMMA) thin film spin-coated on silicon wafer or glass substrate by the alternate dipping of PEtOz-PCL micelles and PAMAM dendrimers in aqueous solution at pH 3. The formation of multilayer thin film was characterized by using ellipsometry, UV-vis spectroscopy, and atomic force microscopy. The PEtOz outer shell of PEtOz-PCL micelle provided the pH-responsive hydrogen bonding sites with peripheral carboxylic acids of PAM AM dendrimer. The multilayer thin film was reversibly removed after dipping in aqueous solution at $pH{\geq}5.6$ due to dissociation of the hydrogen bonding between PEtOz shell of PEtOz-PCL micelle and peripheral carboxyl units of PAMAM dendrimer.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.6
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• pp.216-219
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• 2003

A new class of carbosiloxane dendrimer (G4-48PyP) terminated with 4-pyridylpropano I was synthesized and its possible application to functional thin films was examined through metal complexation and Langmuir-Blodgett (LB) technique. The highly concentrated periphery pyridyl groups of G4-48PyP were exposed on aq. aluminum ions at the air-water interface. The monolayers showed stability up to ca. 50 mN/m of surface pressure. When the subphase became acidic or alkaline, the monolayers changed to condensed phase. The presence of aluminum ions also caused reduction of the molecular area. The macroscopic images of the monolayers were monitored by Brewster angle microscopy (BAM) and only the images of dendrimer aggregates could be observed after the monolayer collapse. The surface images of the monolayer LB film were scanned by atomic force microscopy (AFM). The convex structures of single and aggregate molecules were directly observed. The structures of Langmuir-Blodgett (LB) films were characterized by FT-IR, UV-Vis, and X-ray photoelectron spectroscopy (XPS). The UV-Vis spectrum of the aluminum ion-complexed LB film showed additional band around 670nm, which was not found in the spectra of dendrimer itself or aq. aluminum ions. XPS spectra also supported the incorporation of aluminum ions into the LB films.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.16-18
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• 2002

We attempted to fabricate a dendrimer Langmuir-Blodgett(LB) films containing 48 pyridinepropanol functional end group. As the pyridinepropanol functional group could form a complex structure with metal ions. In this study the samples for electrical measurement were fabricated to two types metal complexes with $Pt^{4+}$ and $Fe^{2+}$ ions by LB method. And we have investigated the surface activity at the air-water interface as well as the electrical properties for the monolayers of pure G4-48PyP dendrimer and its complex with metal ions($Pt^{4+}$ and $Fe^{2+}$ ions). In the surface pressure-area($\pi-A$) isotherms of the dendrimers, the stable condensed films formed at the air-water interface and the metal ions effect showed the difference on molecular behavior. We have studied the electrical properties of the ultra thin dendrimer LB films investigated by the current-voltage(I-V) characteristics of metal/dendrimer LB films/metal(MIM) structure. In conclusion, it is demonstrated that the metal ion around G4-48PyP dendrimer can contribute to make formation of network structure among dendrimers and it result from the change of electrical properties.

• Advances in nano research
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• v.4 no.2
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• pp.145-156
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• 2016

Dendrimers are one of the most appropriate nanocaries for imaging moieties in imaging applications.The purpose of this study was the evalution of cytotoxicity and inducing apoptosis of dendrimers. This study was conducted in order to investigate the metastasis suppression effect of dendrimer in human breast MCF-7 cell line and finding the nanoparticle protein corona in biological enviromental. Dendrimer cytotoxicity effect was assessed by MTT assay. The mRNA experession level of KAI1 as a metastasis suppressor gene, Bax as Pro- apoptotic gene, Bcl-2 as an anti-apoptotic gene and GAPDH as a housekepping gene were determined by real-time PCR assays.concentration-dependent nanoparticle cytotoxicity effect was proofed at range of 1-2 mg/mL in 24 hours, significant upregulation of mRNA expression of Bax, was observed whereas expression of anti-apoptotic Bcl-2 was down-regulated, also expression of metastasis suppressor gene KAI1 was up-regulated. So far a few studies confirmed apoptosis enhancement effect of dendrimers in MCF-7 cell line via bax/bcl-2 pathways. dendrimer nanoparticles was able to act as metastase inhibitor via upregulation of KAI1 gene.

• Journal of Life Science
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• v.30 no.10
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• pp.905-911
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• 2020

The adjuvant effect of PAMAM dendrimer G4 (PAMAM) on the induction of humoral and cellular immune responses against keyhole limpet hemocyanin (KLH) was examined. Mice were immunized subcutaneously twice at two-week intervals with KLH, with or without PAMAM dendrimer (100 ㎍/mouse), and the mice immunized with KLH+PAMAM showed significantly higher antibody titers against KLH than those immunized with KLH alone. The assay for determining the isotypes of the antibodies showed that PAMAM augmented the KLH-specific antibody titers of IgG1, IgG2a, IgG2b, IgG3, and IgM. In addition, mice immunized twice with KLH+PAMAM followed by a subcutaneous injection of KLH (20 ㎍/site) 7 weeks after the primary immunization exhibited a higher delayed-type hypersensitivity (DTH) reaction than those treated with KLH alone. In an in vitro analysis of T lymphocyte proliferation in response to KLH in week 8, the splenocytes of mice treated with KLH+PAMAM showed significantly higher proliferating activity than those treated with KLH alone, and the culture supernatants of cell cultures from mice immunized with added PAMAM dendrimer showed higher levels of KLH-specific cytokine (IL-4 and IFN-r) production. These results suggest that PAMAM dendrimer G4 possesses a potent immune-adjuvant activity for enhancing both humoral and cell-mediated immunity specific to foreign antigens.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.4
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• pp.146-149
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• 2001

The functionalized dendrimer containing 48 azobenzene was synthesized. Many isolated featureless domains were explicitly observed even at the air/water interface. Also, these monolayers were representatively observed, showing the change of surface pressure with irradiation time and wavelength. In AFM images, larger domains irregularly shaped structures on the top, while smaller ones were free from such defects. In the optical absorption spectra of the monolayer films by UV irradiation and heat treatment, only the photoiosmerization of the G4-48 Azo monolayers was observed, revealing a decrease of absorbance peaks without any change of the spectral shape. This suggests that the functional group and the symmetric chain affect optical behavior and morphological change.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1724-1726
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• 2004

Monolayers of lipids on a water surface have attracted much interest as models of biological membranes, but also as precursors of multilayer systems promising many technical applications. Until now, many methodologies have been developed in order to gain a better understand. Photoisomerization in monolayers of a novel azobenzene compound, azobenzene dendrimer, was investigated for the first time by means of the absorption spectrum and Maxwell displacement current (MDC) technique. Dendrimers are well-defined macromolecules exhibiting a tree-like structure, first derived by the cascade molecule approach. According to the absorption spectrum, trans-to-cis conversion ratio was estimated to the third generation of azobenzene dendrimer deposited onto a glass substrate. Temperature-dependent induced charge with trans-cis isomerization was also measured by means of MDC technique.