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Poly(ethylene glycol)을 생체적합 및 흡착 방지 마이크로/나노채널 제작 및 특성 연구
김필남(Pilnam Kim),정훈의(Hoon Eui Jeong),서갑양(Kahp Y. Suh) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
We present a simple solvent-assisted capillary molding method to fabricate zinc oxide (ZnO) nanostructures using an ultraviolet (UV) curable polyurethane acrylate (PUA) mold. A thin film of the ZnO sol-gel precursor solution in methyl alcohol was prepared by spin coating on a solid substrate and subsequently a nanopatterned PUA mold was brought in conformal contact with the substrate under a slight physical pressure (~ 3.5 bar). After annealing at 230 °C for 4 hrs, well-defined ZnO nanostructures formed with feature size down to ~ 50 ㎚ aided by capillary rise and solvent evaporation. It was found that the height of capillary rise highly depended on the applied pressure. A simple experimental setup was devised to examine the effects of pressure, revealing that the optimum pressure ranged from 3.5 to 5 bars. Also, ZnO nanorods could be selectively grown on the patterned regions using the seed layer as a pseudocatalyst when the width of seed layer was larger than ~ 200 ㎚.
김필남(Pilnam Kim),김덕호(Deok-Ho Kim),김병규(Byungkyu Kim),최성규(Seung Kyu Choi),이상호(Sang Ho Lee),Ali Khademhossei,Robert Lang,서갑양(Kahp Y. Suh) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
We developed a method for fabricating poly(ethylene glycol) (PEG) nanostructures using capillary lithography mediated UV exposure. A PEG dimethacrylate (PEG-DMA) was used for crosslinking, which could be applied to other PEG polymers having a crosslinking group. In comparison to unstructured, planar PEG films, the hydrophobicity was significantly enhanced on PEG nanostructures presumably due to embedded air in the nanostructures, as confirmed by contact angle measurements of water. A number of proteins and cells were tested to examine the effects of the modification of surface properties on protein adsorption and cell adhesion. It was found that proteins and cells adhered on a nanostructured PEG surface slightly higher than on a bare PEG film, but much less than on glass control, which could be attributed to the increased surface area and hydrophobicity.
Reversibly bonded nanocapillaries by electrostatic forces for directed alignment of carbon nanotubes
Pilnam Kim(김필남),Kahp Y. Suh(서갑양) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
Reversibly bonded nanocapillaries (500 ? 50 ㎚) were fabricated on gold and silicon substrates using electrostatic forces that can be generated on a rigiflex mold upon removal from an original, engraved silicon master. Polyethylene glycol diacrylate (PEG-DA) was used as a rigiflex mold material with highly negative surface charges (zeta potential: - 113.55 ㎽).). The rigiflex, transparent PEG-DA mold spontaneously wets gold or silicon substrate via electrostatic attraction, forming reversibly bonded nanocapillaries without any surface modifications or external stimuli. Using these nanocapillaries, nanolines or nanowells were fabricated without residual layer along with one-dimensional arrays of single-walled carbon nanotubes (SWCNTs) and gold nanoparticles(NPs).
Capillary-driven Rigiflex Lithography for Fabricating High Aspect-Ratio Polymer Nanostructures
정훈의(Hoon Eui Jeong),이성훈(Sung Hoon Lee),김필남(Pilnam Kim),서갑양(Kahp Y. Suh) 한국가시화정보학회 2007 한국가시화정보학회지 Vol.5 No.1
We present simple methods for fabricating high aspect-ratio polymer nanostructures on a solid substrate by rigiflex lithography with tailored capillarity and adhesive force. In the first method, a thin, thermoplastic polymer film was prepared by spin coating on a substrate and the temperature was raised above the polymer’s glass transition temperature (T<SUB>g</SUB>) while in conformal contact with a poly(urethane acrylate) (PUA) mold having nano-cavities. Consequently, capillarity forces the polymer film to rise into the void space of the mold, resulting in nanostructures with an aspect ratio of ~ 4. In the second method, very high aspect-ratio (>20) nanohairs were fabricated by elongating the pre-formed nanostructures upon removal of the mold with the aid of tailored capillarity and adhesive force at the mold/polymer interface. Finally, these two methods were further used to fabricate micro/nano hierarchical structures by sequential application of the molding process for mimicking nature’s functional surfaces such as a lotus leaf and gecko foot hairs.
마이크로채널 내에서 부착력 차이에 의한 유방암세포의 선별 및 농축
권건우(Keon Woo Kwon),박민철(Min Cheol Park),김필남(Pilnam Kim),황세연(Se Yon Hwang),이상호(Sang Ho Lee),김병규(Byungkyu Kim),서갑양(Kahp Y. Suh) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
A label-free microfluidic method for separation and enrichment of human breast cancer cells is presented using cell adhesion as a physical marker. To maximize the adhesion difference between human breast epithelial cells (MCF10A) and cancer cells (MCF7), flat or nanostructured polymer surfaces (400nm pillars, perpendicular, or parallel line) were constructed on the bottom of PDMS microfluidic channels using UVassisted capillary moulding. The adhesion of MCF10A and MCF7 on each channel was measured based on detachment assays where the adherent cells were counted with increasing flow rate after a pre-culture for a period of time (e.g., 1, 2, and 4 hrs). It was found that MCF10A cells show higher adhesion than MCF7 cells regardless of surface nanotopography. The optimum separation was found for 2 hours pre-culture on the 400nm perpendicular line pattern at a flow rate of 200 μl/min. The fraction of MCF7 cells was increased from 0.36 ± 0.04 to 0.83 ± 0.04 under these optimized conditions.
정훈의(Hoon Eui Jeong),이성훈(Sung Hoon Lee),김필남(Pilnam Kim),서갑양(Kahp Y. Suh) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
A new, innovative approach for fabricating high aspect-ratio polymer nanohairs is presented, which is based on an elongation of polymer nanostructures by interfacial energy modulation. Calculation of two interfacial energies at the mold/polymer and the polymer/substrate interface indicates that the two energies should be compatible for successful elongation of the polymer nanostructures. By this approach, high aspectratio polymer (PMMA and PS) nanostructures were fabricated with maximum ratio up to ~ 25 on a solid substrate with good uniformity and reproducibility. A double-sided flexible tape fabricated by this approach shows good adhesive property and super-hydrophobicity, demonstrating the unique fabrication ability and applicability of this method.