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Synthesis of Novel Biodegradable Cationic Dendrimers
Lee, Jin-Seong,Huh, June,Ahn, Cheol-Hee,Lee, Minhyung,Park, Tae Gwan WILEY-VCH Verlag 2006 Macromolecular rapid communications Vol.27 No.18
<P>Summary: Dendrons and dendrimers with cationic amino groups at their periphery were successfully synthesized up to the third and second generation, respectively. The results obtained by <SUP>1</SUP>H NMR spectroscopy and gel permeation chromatography analysis supported the formation of the targeted dendrons and dendrimers. The dendrons were grown via ester linkages, which endowed them with biodegradability in D<SUB>2</SUB>O at 37 °C. The degradation rate depends upon the steric hindrance and reactivity caused by the bulkiness and compact structure of the dendrons. All of the synthesized dendrons were degraded within a month, while 60% of the ester groups in the sterically crowded dendrimers were degraded over the same time period. The cytotoxicity of the dendrons was evaluated by the MTT assay on a 293T cell line which indicated that the obtained dendrons were completely non-toxic. These non-toxic, biodegradable cationic dendrons and dendrimers are believed to have potential applications in the biomedical field.</P><P> <img src='wiley_img/10221336-2006-27-18-MARC200600393-gra001.gif' alt='wiley_img/10221336-2006-27-18-MARC200600393-gra001'> Graphic Synthetic procedure of dendrons and dendrimers. </P>
Self-Organization of Dendron-Poly(ethylene glycol) Conjugates in an Aqueous Phase
Kim, Kyoung-Taek,Lee, Im-Hae,Park, Chiyoung,Song, Yu-Mi,Kim, Chul-Hee The Polymer Society of Korea 2004 Macromolecular Research Vol.12 No.5
We have prepared amide dendrons having alkyl peripheral units and various focal moieties through a convergent synthetic approach. The amphiphilic properties, due to hydrophilic amide branches and the hydrophobic peripheral units, provide an opportunity for the amide dendrons to self-organize in water. The dendritic architecture itself is also one of the critical factors in the self-organization of the amide dendrons in water. In particular, function-alization was performed at the focal point to elucidate the relationship between the focal functionality and the self-organized structures of the dendritic building blocks in the aqueous phase. The dendron having a short poly(ethylene glycol) monomethyl ether (MeO-PEG) unit (M$\_$n/ =750) as the focal moiety formed a vesicular organization in water. As the size of the hydrophilic focal MeO-PEG increased to M$\_$n/ =2,000 and 5,000, the self-organized structures became rod-type and spherical micelles, respectively. Our observation of multiple morphologies for amide dendrons is in good agreement with previous reports that indicated that the micellar structures changed from vesicles to rod-types and then to spheres upon increasing the size of the hydrophilic moiety of the amphiphiles.
Solvent Effects on Self-Assembly and Superstructures of Amide Dendrons
전혜진,송현훈,김철희 한국고분자학회 2012 Macromolecular Research Vol.20 No.9
Supramolecular ordering via self-assembly of amide dendrons was investigated in different solvents. The selection of the solvents strongly affected the supramolecular ordering of third generation dendrons depending on the solubility strength while only a minimal effect was seen with the first and second generation dendrons. The number of amide branches and alkyl tails which are responsible for the hydrogen bond and steric hindrance determined the solvent effect. Relatively low numbers of branches in the first and second generation dendrons compared with the third generation resulted in the minimal solvent effect. Solutions of low solubility favoring collapsed and extended conformation of third generation dendrons induced lamellar superstructure, while solutions of high solubility favoring expanded globular conformation formed columnar superstructures. The results were discussed based on the Kamlet-Taft parameters of the solvents.
Direct Detection of Drug-Resistant Hepatitis B Virus in Serum Using a Dendron-Modified Microarray
( Doo Hyun Kim ),( Hong Seok Kang ),( Seong-suk Hur ),( Seobo Sim ),( Sung Hyun Ahn ),( Yong Kwang Park ),( Eun-sook Park ),( Ah Ram Lee ),( Soree Park ),( So Young Kwon ),( Jeong-hoon Lee ),( Kyun-hw 대한간학회 2018 Gut and Liver Vol.12 No.3
Background/Aims: Direct sequencing is the gold standard for the detection of drug-resistance mutations in hepatitis B virus (HBV); however, this procedure is time-consuming, labor-intensive, and difficult to adapt to high-throughput screening. In this study, we aimed to develop a dendron-modified DNA microarray for the detection of genotypic resistance mutations and evaluate its efficiency. Methods: The specificity, sensitivity, and selectivity of dendron-modified slides for the detection of representative drug-resistance mutations were evaluated and compared to those of conventional slides. The diagnostic accuracy was validated using sera obtained from 13 patients who developed viral breakthrough during lamivudine, adefovir, or entecavir therapy and compared with the accuracy of restriction fragment mass polymorphism and direct sequencing data. Results: The dendron-modified slides significantly outperformed the conventional microarray slides and were able to detect HBV DNA at a very low level (1 copy/μL). Notably, HBV mutants could be detected in the chronic hepatitis B patient sera without virus purification. The validation of our data revealed that this technique is fully compatible with sequencing data of drug-resistant HBV. Conclusions: We developed a novel diagnostic technique for the simultaneous detection of several drug-resistance mutations using a dendron-modified DNA microarray. This technique can be directly applied to sera from chronic hepatitis B patients who show resistance to several nucleos(t)ide analogues. (Gut Liver 2018;12:331-341)
Hirao Akira,Tsunoda Yuji,Matsuo Akira,Sugiyama Kenji,Watanabe Takumi The Polymer Society of Korea 2006 Macromolecular Research Vol.14 No.3
Dendritic hyperbranched poly(methyl methacrylate)s (PMMA)s, whose branched architectures resemble the 'dendron' part(s) of dendrimer, were synthesized by an iterative methodology consisting of two reactions in each iteration process: (a) a coupling reaction of u-functionalized, living, anionic PMMA having two tert-butyldimethylsilyloxymethylphenyl(SMP) groups with benzyl bromide(BnBr)-chain-end-functionalized PMMA, and (b) a transformation reaction of the introduced SMP groups into BnBr functionalities. These two reactions, (a) and (b), were repeated three times to afford a series of dendron-like, hyperbranched (PMMA)s up to third generation. Three dendron-like, hyperbranched (PMMA)s different in branched architecture were also synthesized by the same iterative methodology using a low molecular weight, functionalized 1,1-diphenylalkyl anion prepared from sec-BuLi and 1,1-bis(3-tert-butyldime-thylsilyloxymethylphenyl)ethylene in the reaction step (b) in each iterative process. Furthermore, structurally similar, dendron-like, hyperbranched block copolymers could be successfully synthesized by the iterative methodology using $\alpha$-functionalized, living, anionic poly(2-(perfluorobutyl) ethyl methacrylate) (PRfMA) in addition to $\alpha$-functionalized, living PMMA. Accordingly, the resulting block copolymers were comprised of both PMMA and PRfMA segments with different sequential orders. After the block copolymers were cast into films and annealed, their surface structures were characterized by angle-dependent XPS and contact angle measurements. All three samples showed significant segregation and enrichment of PRfMA segments at the surfaces.
Park, Chiyoung,Im, Moon Sup,Lee, Sanghwa,Lim, Jino,Kim, Chulhee WILEY-VCH Verlag 2008 Angewandte Chemie Vol.47 No.51
<B>Graphic Abstract</B> <P>Take the tube: A systematic approach was used to construct a series of functional nanotubes by cooperative self-assembly of dendrons and cyclodextrins and their nanotube–nanoparticle hybrids (see picture). The nanotubes are also capable of sensing proteins by inducing specific binding of proteins on the tube surface. The “nanotube toolkit” has a great potential for the construction of functional nanomaterials. <img src='wiley_img/14337851-2008-47-51-ANIE200804087-content.gif' alt='wiley_img/14337851-2008-47-51-ANIE200804087-content'> </P>
Hayakawa Teruaki,Kouketsu Takayuki,Kakimoto Masa-alki,Yokoyama Hideaki,Horiuchi Shin The Polymer Society of Korea 2006 Macromolecular Research Vol.14 No.1
A novel fabrication of the patterned surfaces in the polymer films was demonstrated by using the self-organizing character of the block copolymers of polystyrene-b-oligothiophenes and polystyrene-b-aromatic amide dendron. Hexagonally arranged open pores with a micrometer-size were spontaneously formed by casting the polymer solutions under a moist air flow. The amphiphilic character of the block copolymers played the crucial role as a surfactant to stabilize the inverse emulsion of water in the organic solvent, and subsequently the aggregated structure of the hydrophilic oligothiophene or aromatic amide dendron segments remained on the interiors of the micropores. The chemical composition on the top of the surface of the microporous films was characterized by energy-filtering transmission electron microscopy (EFTEM) or a time-of-flight secondary ion mass spectrometer (ToF-SIMS). The characterizations clearly indicated that the patterned surfaces in the self-organized block copolymer films with the hexagonally ordered microporous structures were fabricated in a single step.