• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1422-1424
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• 2009

Modified self-assembled $TiO_2$ and polyelectrolyte multilayer film have been used as OTFT insulator. Both films were used as gate insulator and their thickness were reduced to the order of 10nm. The operating voltage of OTFT was substantially reduced due to nanoscale thickness of titanium oxide and polyelectrolyte multilayer. Pentacene-based OTFT characteristics will be discussed.

• KSBB Journal
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• 제24권6호
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• pp.515-520
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• 2009

This study presented facile method of cell patterning using fabricated PDMS patterns on polyelectrolyte coated surface. This basic principle is the fabrication of functional surface presenting two orthogonal surfaces such as cell adhesive and repellent properties. Cell adhesive surface was firstly fabricated with simple coating of polyelectrolyte multilayer. And then, the desired patterns of PDMS for the prevention of nonspecific binding of cells were transferred onto the previously formed thin film of polyelectrolyte multilayer. Thus, we could prepare novel functional surface simultaneously containing PDMS and polyelectrolyte region. As expected, the PDMS regions showed effective prevention of nonspecific binding of cell and the other region, exposed polyelectrolyte area, provided cell adhesive environment. The height of formed PDMS structure was about 100 nm. Based on this method, cell patterning can be successfully obtained with various pattern shapes and sizes. Therefore, we expect that this simple method will be useful platform technology for the development of cell chip, cell based assay system, and biochip.

• Macromolecular Research
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• 제16권4호
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• pp.373-378
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• 2008

A simple chemical fixation method for the fabrication of layer-by-layer (LbL) polyelectrolyte multilayer (PEM) has been developed to create a large area, highly uniform film for various applications. PEM of weak poly-electrolytes, i.e., polyallylamine hydrogen chloride (PAH) and poly(acrylic acid)(PAA), was assembled on polymer substrates such as poly(methyl methacrylate)(PMMA) and polycarbonate (PC). In the case of a weak polyelectrolyte, the fabricated thin film thickness of the polyelectrolyte multilayers was strongly dependent on the pH of the processing solution, which enabled the film thickness or optical properties to be controlled. On the other hand, the environmental stability for device application was poor. In this study, we utilized the chemical fixation method using glutaraldehyde (GA)-amine reaction in order to stabilize the polyelectrolyte multilayers. By simple treatment of GA on the PEM film, the inherent morphology was fixed and the adhesion and mechanical strength were improved. Both surface tension and FT-IR measurements supported the chemical cross-linking reaction. The surface property of the polyelectrolyte films was altered and converted from hydrophilic to hydrophobic by chemical modification. The possible application to antireflection coating on PMMA and PC was demonstrated.

• Korean Chemical Engineering Research
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• 제48권2호
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• pp.178-184
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• 2010

본 논문에서는 생체적합성 고분자들의 자기 조립 특성을 이용하여 마이크론 단위의 캡슐을 제조하여, 캡슐 내부에 단백질을 넣고 시간과 pH에 따른 방출 거동을 고찰하였다. 본 연구에서는 키토산과 헤파린 그리고 알지네이트를 사용하여 동공(hollow) 캡슐을 제조하였다. 멜라민과 포름알데히드를 일정 비율로 혼합하여, 표면에 전하를 가지는 마이크론 단위의 core를 제조한 후, 음전하를 가지는 헤파린 혹은 알지네이트를 core 위에 흡착시키고, 양전하를 띠는 키토산을 흡착시킨 후, core 위에 교대로 흡착시켜 Multilayer를 형성시켰다. 4 층을 쌓은 후에 HCl을 이용하여 pH 2로 조절하면, core는 제거되고 속이 비어 있는 캡슐을 제조할 수 있었다. 동공 캡슐은 투과전자현미경, 표면주사현미경 및 광학현미경으로 관찰하였다. 이러한 캡슐은 pH에 따라서 각기 다른 거동을 보이는데, 본 연구에서는 내부에 FITC-albumin을 넣어 UV분광기로 방출되는 상대적인 양을 관찰한 결과, 키토산-헤파린 캡슐과 키토산-알지네이트 캡슐은 각기 다른 pH에서 개폐됨을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제19권11호
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• pp.1156-1160
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• 1998

Alternating multilayer films of a cationic bipolar amphiphile and an anionic polyelectrolyte were prepared by a self-assembly method based on electrostatic attraction between opposite charges. The bipolar amphiphile contains an azobenzene unit in order to allow for a trans-cis photoisomerization to take place. Optical birefringence or dichroism was induced in the self-assembled film upon linearly polarized light irradiation. This dichroism could be reversibly written and erased by irradiation with light of an appropriate wavelength.

• Biotechnology and Bioprocess Engineering:BBE
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• 제9권3호
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• pp.179-183
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• 2004

A biocompatible polyelectrolyte complex multilayer (PECML) film consisting of poly-L-lysine (PLL) as a polycation and hyaluronic acid (HA) as a polyanion was developed to test its use for surface modification to prevent cell attachment and protein drug delivery. The formation of PECML through the electrostatic interaction of HA and PLL was confirmed by contact angle measurement, ESCA analysis, and HA content analysis. HA content increased rapidly up to 8 cycles for HA/PLL deposition and then slightly increased with an increasing number of deposition cycle. In vitro release of PLL in the PECML continued up to 4 days and ca. 25% of HA remained on the chitosan-coated cover glass after in vitro release test for 7 days. From the results, PECML of HA and PLL appeared to be stable for about 4 days. The surface modification of the chitosan-coated cover glass with PECML resulted in drastically reduced peripheral blood mononuclear cell (PBMC) attachment. Concerned with its use for protein drug delivery, we confirmed that bovine serum albumin (BSA) as a model protein could be incorporated into the PECML and its release might be triggered by the degradation of HA with hyaluronidase.

• Korea-Australia Rheology Journal
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• 제15권1호
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• pp.1-7
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• 2003

A new method is introduced to build up organic/organic multilayer films composed of cationic poly(allylamine hydrochloride) (PAH) and negatively charged poly (sodium 4-styrenesulfonate) (PSS) using the spinning process. The adsorption process is governed by both the viscous force induced by fast solvent elimination and the electrostatic interaction between oppositely charged species. On the other hand, the centrifugal and air shear forces applied by the spinning process significantly enhances desorption of weakly bound polyelectrolyte chains and also induce the planarization of the adsorbed polyelectrolyte layer. The film thickness per bilayer adsorbed by the conventional dipping process and the spinning process was found to be about 4 ${\AA}$ and 24 ${\AA}$, respectively. The surface of the multilayer films prepared with the spinning process is quite homogeneous and smooth. Also, a new approach to create multilayer ultrathin films with well-defined micropatterns in a short process time is Introduced. To achieve such micropatterns with high line resolution in organic multilayer films, microfluidic channels were combined with the convective self-assembly process employing both hydrogen bonding and electrostatic intermolecular interactions. The channels were initially filled with polymer solution by capillary pressure and the residual solution was then removed by the .spinning process.

• 폴리머
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• 제29권4호
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• pp.392-398
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• 2005

Layer-by-layer(LbL) 흡착에 의한 poly(ethylene-alt-m미? anhydride) (PEMAh)/poly(4-vinyl pyridine) (P4VP) 자기조립 다층박막을 제조하였다. 자기조립 다층막을 이루는 PEMAh/P4VP 두 고분자 사이의 수소 결합과 정전기적 인력이 다층막을 이루는 원동력이라는 것이 푸리에 변환 적외선(FT-IR) 분광분석에 의해서 확인되었다. 다층막의 균일한 자기조립 과정은 PEMAh/P4VP 이중층막의 적층 수 증가에 따른 UV-vis 스펙트럼의 256 nm에서 나타나는 P4VP 특성 흡수 피크의 선형적 증가에 의해서 확인할 수 있었다. 다층막을 이루는 고분자 전해질 담지 용액의 조건 변화가 다층막 형성에 미치는 영향을 살펴보기 위하여 두 고분자 용액의 농도 및 PEMAh 담지용액의 pH를 변화시키면서 다층막을 제조하였다. 다층막의 두께, 흡착된 고분자 전해질 질량 및 표면 거칠기의 변화를 UV-vis 분광 분석, 수정진동자 미량저울(quartz crystal microbalance;QCM) 및 원자 힘 현미경(atomic force microscopy;AFM)을 이용하여 측정하였다.

• Macromolecular Research
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• 제17권4호
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• pp.232-239
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• 2009

This paper describes the simple nanopatterning of proteins on polyelectrolyte surfaces using microcontact printing with a nanopatternable, hydrophilic composite nanomold. The composite nanomold was easily fabricated by blending two UV-curable materials composed of Norland Optical Adhesives(NOA) 63 and poly(ethylene glycol) dimethacrylate(PEG-DMA). NOA 63 provided stable nanostructure formation and PEG-DMA induced high wettability of proteins in the nanomold. Using the composite mold and functionalized surface with polyelectrolytes, the fluorescent, isothiocyanate-tagged, bovine serum albumin(FITC-BSA) was successfully patterned with 8 nm height and 500 nm width. To confirm the feasibility of the protein assay on a nanoscale, a glycoprotein-lectin assay was successfully demonstrated as a model system. As expected, the lectins correctly recognized the nano-patterned glycoproteins such as chicken ovalbumin. The simple preparation of composite nanomold and functionalized surface with a universal platform can be applied to various biomolecules such as DNA, proteins, carbohydrates, and other biomolecules on a nanoscale.

• Korean Chemical Engineering Research
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• 제46권6호
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• pp.1100-1106
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• 2008

본 연구는 표면에 세포를 부착하는데 있어서, 다양한 기판 표면에 보편적인 플랫폼으로써 적용될 수 있는 세포 부착을 위한 기능성 표면의 제작 기술 및 이를 이용한 세포의 선택적인 고정과 편리한 세포 패터닝의 방법을 보여주었다. 세포 부착에 적합한 기능성 표면의 제작은 산소 플라즈마 처리를 이용한 다양한 기판의(유리, PMMA, PS, PDMS) 표면 활성화 및 상반되는 고분자 전해질의(PAH, PDAC, PSS, PAA) 정전기적 인력을 통한 증착으로 이루어진 다층의 고분자 전해질 층을 통해 제작될 수 있었다. 또한, 고분자 전해질로 증착된 표면 위로 마이크로 몰딩 인 케필러리 방법을 사용하여 PEG 마이크로 구조물을 제작함으로써 세포의 선택적인 고정이 이루어질 수 있었다. 다층의 고분자 전해질로 증착된 표면은 세포와의 강한 정전기적 인력으로 세포 부착에 유리한 표면을 제공하였다. 반면에, 제작된 PEG 마이크로 구조물은 물리적, 생물학적인 장애물의 역할로써 세포의 비 특이적인 흡착을 방지하였다. 세포 부착을 위한 기능성 표면을 제작하는 동안 표면의 특성은 접촉각 측정을 통해 이루어 졌다. 다양한 기판 상에서 개질된 표면은 세포 부착을 위한 적합한 환경의 제공과 함께 세포의 마이크로 패터닝 기술에서 높은 수율의 세포 패터닝을 제공한다. 상기의 제안된 세포 부착을 위한 기능성 표면 제작 기술 방법은 제작 과정이 매우 간단하고, 편리하여 손쉽게 구현이 가능하며, 제작 공정에서 어떠한 해로운 용매도 사용하지 않기 때문에 친환경적이다. 또한, 이를 이용하여 세포를 이용하는 바이오 칩 및 바이오 센서, 세포를 기반으로 하는 시스템 등에서 기본이 되는 기술로 사용될 수 있는 넓은 응용 범위를 갖는다.