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- 저자 : Haeshin Lee (검색결과 88 건)
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Lee, Jung Seung,Lee, Jong Seung,Lee, Min Suk,An, Soohwan,Yang, Kisuk,Lee, Kyueui,Yang, Hee Seok,Lee, Haeshin,Cho, Seung-Woo American Chemical Society 2017 Chemistry of materials Vol.29 No.10
<P>Application of surface chemistry using bioactive compounds enables simple functionalization of tissue-engineering scaffolds for improved biocompatibility and regenerative efficacy. Recently, surface modifications using natural polyphenols have been reported to serve as efficient multifunctional coating; however, there has yet to be any comprehensive application in tissue engineering. Here, we report a simple, multifunctional surface modification using catechin, a phenolic compound with many biological functions, found primarily in plants, to potentiate the functionality of polymeric scaffolds for bone regeneration by stem cells. We found that catechin hydrate can be efficiently deposited on the surface of various substrates and can greatly increase hydrophilicity of the substrates. While identifying the chemical mechanisms regulating catechin surface coating, we found that catechin molecules can self-assemble into dimers via cation-pi interactions. Interestingly, the intrinsic biochemical functions of catechin coating provided the polymer scaffolds with antioxidative and calcium-binding abilities, resulting in enhanced adhesion, proliferation, mineralization, and osteogenic differentiation of human adipose-derived stem cells (hADSCs). Ultimately, catechin-functionalized polymer nanofiber scaffolds significantly promoted in vivo bone formation by hADSC transplantation in a critical-sized calvarial bone defect. Our study demonstrates that catechin can provide a biocompatible, multifunctional, and cost-effective surface modification chemistry to produce functional scaffolds with improved tissue regenerative efficacy.</P>
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Material-Independent Surface Chemistry beyond Polydopamine Coating
Lee, Haesung A.,Ma, Yanfei,Zhou, Feng,Hong, Seonki,Lee, Haeshin American Chemical Society 2019 Accounts of chemical research Vol. No.
<P><B>Conspectus</B></P><P>Various methods have been developed in surface chemistry to control interface properties of a solid material. A selection rule among surface chemistries is compatibility between a surface functionalization tool and a target material. For example, alkanethiol deposition on noble metal surfaces, widely known as the formation of a self-assembled monolayer (SAM), cannot be performed on oxide material surfaces. One must choose organosilane molecules to functionalize oxide surfaces. Thus, the surface chemistry strictly depends on the properties of the surface. Polydopamine coating is now generally accepted as the first toolbox for functionalization of virtually any material surface. Layer-by-layer (LbL) assembly is a widely used method to modify properties of versatile surfaces, including organic materials, metal oxides, and noble metals, along with polydopamine coating. On flat solid substrates, the two chemistries of polydopamine coating and LbL assembly provide similar levels of surface modifications. However, there are additional distinct features in polydopamine. First, polydopamine coating is effective for two- or three-dimensional porous materials such as metal-organic frameworks (MOFs), synthetic polyolefin membranes, and others because small-sized dopamine (MW = 153.18 u) and its oxidized oligomers are readily attached onto narrow-spaced surfaces without exhibiting steric hindrance. In contrast, polymers used in LbL assembly are slow in diffusion because of steric hindrance due to their high molecular weight. Second, it is applicable to structurally nonflat surfaces showing special wettability such as superhydrophobicity or superoleophobicity. Third, a nonconducting, insulating polydopamine layer can be converted to be a conducting layer by pyrolysis. The product after pyrolysis is a N-doped graphene-like material that is useful for graphene or carbon nanotube-containing composites. Fourth, it is a suitable method for engineering the surface properties of various composite materials. The surface properties of participating components in composite materials can be unified by polydopamine coating with a simple one-step process. Fifth, a polydopamine layer exhibits intrinsic chemical reactivity by the presence of catecholquinone moieties and catechol radical species on surfaces. Nucleophiles such as amine and thiolate spontaneously react with the functionalized layer.</P><P>Applications of polydopamine coating are exponentially growing and include cell culture/patterning, microfluidics, antimicrobial surfaces, tissue engineering, drug delivery systems, photothermal therapy, immobilization of photocatalysts, Li-ion battery membranes, Li-sulfur battery cathode materials, oil/water separation, water detoxification, organocatalysts, membrane separation technologies, carbonization, and others. In this Account, we describe various polydopamine coating methods and then introduce a number of chemical derivatives of dopamine that will open further development of material-independent surface chemistry.</P> [FIG OMISSION]</BR>
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Lee, Haeshin,Jeong, Ji-Hoon,Lee, Je-Hoon,Park, Tae-Gwan The Korean Society for Biotechnology and Bioengine 2001 Biotechnology and Bioprocess Engineering Vol.6 No.4
This study presents a new formulation method for improving DNA transfection effi-ciency using a fusogenic peptide and polyethylene glycol-grafted polyethylenimine. Succinimidyls succinate polyethylene glycol (PEG-SSA) was conjugated with polyethylenimine(PEL). PEL is well known for a good endosomal escaping and DNA condensign agent. The positively charged syn-thetic fusogenic peptide, KALA was coated on the negatively charged PEG-g-PEI/DNA and PEI/DNA complexes. The KALA/PEI/ DNA complexes exhibited aggregation behavior at higher KALA coating amount with an effective diameter of around 1,000 nm. However, the LALA/PEG-g-PEI/DNA complexes were 100-300 nm in size with a surface zeta-potential (ζ)value of about +20mV. The conjugated PEG molecules suppressed any KALA-mediated inter-particle aggregation, and thereby improved the transfection efficiency, Consequently, the transfection efficiency of the KALA/PEG-g-PEI/DNA complexes was obtained by utilizing both the fusogenic activity of KALA and the steric repulsion effect of PEC.
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Salting Up of Chemically Modified Graphene to Assemble Large-Scale Transparent Conductive Films
Lee, Kyueui,Lee, Haeshin,Ryu, Seongwoo American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.11
<P>I report a method for assembling large-scale transparent conductive films (TCFs) through the phenomenon of 'salting up' of chemically modified graphene (CMG) in the presence of metallic salts. The method described herein was inspired by the well-known protein purification process, 'salting-out.' In contrast, addition of hydrophobic CMGs to the solution of a salt results in 'salting-up' of CMGs. Owing to the presence of the salt, dehydrated CMG flakes spontaneously form an extremely thin layer at the air-water interface. The salted-up CMGs spontaneously form an extremely thin layer of CMGs at air-water interface, which is a useful method to prepare a conducting film with an extremely largearea. This CMG film can be transferred to any other flexible substrate as a TCF film and be enlarged to a greater scale depending on size of air-water interface. I demonstrate a new way to fabricate TCF film that can be applied in the fabrication of large scale graphene-based electronic devices.</P>
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Lee, Sang-woo,Ryu, Ji Hyun,Do, Min Jae,Namkoong, Eun,Lee, Haeshin,Park, Kyungpyo American Chemical Society 2020 ACS APPLIED MATERIALS & INTERFACES Vol.12 No.4
<P>Recently, there has been growing interest in replacing severely damaged salivary glands with artificial salivary gland functional units created in vitro by tissue engineering approaches. Although various materials such as poly(lactic-<I>co</I>-glycolic acid), polylactic acid, poly(glycolic acid), and polyethylene glycol hydrogels have been used as scaffolds for salivary gland tissue engineering, none of them is effective enough to closely recapitulate the branched structural complexity and heterogeneous cell population of native salivary glands. Instead of discovering new biomaterial candidates, we synthesized hyaluronic acid-catechol (HACA) conjugates to establish a versatile hyaluronic acid coating platform named “NiCHE (nature-inspired catechol-conjugated hyaluronic acid environment)” for boosting the salivary gland tissue engineering efficacy of the previously reported biomaterials. By mimicking hyaluronic acid-rich niche in the mesenchyme of embryonic submandibular glands (eSMGs) with NiCHE coating on substrates including polycarbonate membrane, stiff agarose hydrogel, and polycaprolactone scaffold, we observed significantly enhanced cell adhesion, vascular endothelial and progenitor cell proliferation, and branching of in vitro-cultured eSMGs. High mechanical stiffness of the substrate is known to inhibit eSMG growth, but the NiCHE coating significantly reduced such stiffness-induced negative effects, leading to successful differentiation of progenitor cells to functional acinar and myoepithelial cells. These enhancement effects of the NiCHE coating were due to the increased proliferation of vascular endothelial cells via interaction between CD44 and surface-immobilized HAs. As such, our NiCHE coating platform renders any kind of material highly effective for salivary gland tissue culture by mimicking in vivo embryonic mesenchymal HA. Based on our results, we expect the NiCHE coating to expand the range of biomaterial candidates for salivary glands and other branching epithelial organs.</P> [FIG OMISSION]</BR>
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Lee, Yuhan,Chung, Hyun Jung,Yeo, Sangho,Ahn, Cheol-Hee,Lee, Haeshin,Messersmith, Phillip B.,Park, Tae Gwan Royal Society of Chemistry 2010 SOFT MATTER Vol.6 No.5
<P>Hyaluronic acid (HA) hydrogels are widely pursued as tissue regenerative and drug delivery materials due to their excellent biocompatibility and biodegradability. Inspired by mussel adhesion, we report here a novel class of thermo-sensitive and injectable HA/Pluronic F127 composite tissue-adhesive hydrogels applicable for various biomedical applications. HA conjugated with dopamine (HA-DN) was mixed with thiol end-capped Pluronic F127 copolymer (Plu-SH) to produce a lightly cross-linked HA/Pluronic composite gel structure based on Michael-type catechol-thiol addition reaction. The HA/Pluronic hydrogels exhibited temperature-dependent sol–gel phase transition behaviors different from Pluronic hydrogels. Rheological studies showed that the sol–gel transitions were rapid and reversible in response to temperature. The HA/Pluronic hydrogels could be injected <I>in vivo</I> in a sol state at room temperature using a syringe, but immediately became a robust gel state at body temperature. The <I>in situ</I> formed hydrogels exhibited excellent tissue-adhesion properties with superior <I>in vivo</I> gel stability and are potentially useful for drug and cell delivery.</P> <P>Graphic Abstract</P><P>A new class of sol–gel phase transition hydrogels were fabricated using dopamine-conjugated hyaluronic acid and thiolated Pluronic. The hydrogels were thermo-sensitive, injectable, and tissue adhesive. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b919944f'> </P>
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