• Macromolecular Research
• /
• 제16권7호
• /
• pp.626-630
• /
• 2008

Poly(vinyl pyrrolidone) was used successfully to control the size and distribution of silver nanoparticles generated on inorganic silica nanofibers. The inorganic nanofibers were electro spun using sol-gel chemistry of silicates, and the diameter of the prepared nanofibers was unaffected by adding up to 7% of poly(vinyl pyrrolidone). The silver ions, in the form of silver nitrate, were introduced into the silica nanofibers and reduced to metallic silver by ultraviolet irradiation with a subsequent thermal treatment. The size of the generated silver particles was decreased dramatically by adding poly(vinyl pyrrolidone). The size of the silver nanoparticles was 73 nm when no poly(vinyl pyrrolidone) was added but 23 nm with the addition of only 1% of poly(vinyl pyrrolidone). The extent of reduction could be checked by determining the concentration of silver ions leached into water from the silica nanofibers. After thermal treatment of the silica nanofibers, more than 99% of the silver remained in the nanofibers, indicating almost complete reduction of the silver ions to silver metal.

• 한국세라믹학회지
• /
• 제37권4호
• /
• pp.376-380
• /
• 2000

Carbon nanofibers with an average diameter of 100nm were reacted with SiO vapor generated from a mixture of Si and SiO2 to produce silicon carbide nanofibers at temperature ranging 1200∼1500$^{\circ}C$ under vacuum. The nanofiber reacted at 1200$^{\circ}C$ for two hours consisted of silicon carbide with an average crystallite size of 10-20nm, amorphous silica and a significant amount of unreacted carbon. The surface area of silicon carbide nanofiber, obtained after removal of amorphous silica and unreacted carbon from converted carbon nanofibers at 1200$^{\circ}C$, was as high as 150㎡/g. With increasing reaction temperature to 1500$^{\circ}C$, the surface area was decreased to 14㎡/g. Growth of SiC crystallite size with increasing conversion temperature of carbon nanofiber was confirmed from Scherrer formula using the (111) diffraction line and TEM images of converted carbon nanofibers.

• Tissue Engineering and Regenerative Medicine
• /
• 제15권6호
• /
• pp.735-750
• /
• 2018

BACKGROUND: The major challenge of tissue engineering is to develop constructions with suitable properties which would mimic the natural extracellular matrix to induce the proliferation and differentiation of cells. Poly(${\varepsilon}$-caprolactone)-poly(ethylene glycol)-poly(${\varepsilon}$-caprolactone) (PCL-PEG-PCL, PCEC), chitosan (CS), nano-silica ($n-SiO_2$) and nano-hydroxyapatite (n-HA) are biomaterials successfully applied for the preparation of 3D structures appropriate for tissue engineering. METHODS: We evaluated the effect of n-HA and $n-SiO_2$ incorporated PCEC-CS nanofibers on physical properties and osteogenic differentiation of human dental pulp stem cells (hDPSCs). Fourier transform infrared spectroscopy, field emission scanning electron microscope, transmission electron microscope, thermogravimetric analysis, contact angle and mechanical test were applied to evaluate the physicochemical properties of nanofibers. Cell adhesion and proliferation of hDPSCs and their osteoblastic differentiation on nanofibers were assessed using MTT assay, DAPI staining, alizarin red S staining, and QRT-PCR assay. RESULTS: All the samples demonstrated bead-less morphologies with an average diameter in the range of 190-260 nm. The mechanical test studies showed that scaffolds incorporated with n-HA had a higher tensile strength than ones incorporated with $n-SiO_2$. While the hydrophilicity of $n-SiO_2$ incorporated PCEC-CS nanofibers was higher than that of samples enriched with n-HA. Cell adhesion and proliferation studies showed that n-HA incorporated nanofibers were slightly superior to $n-SiO_2$ incorporated ones. Alizarin red S staining and QRT-PCR analysis confirmed the osteogenic differentiation of hDPSCs on PCEC-CS nanofibers incorporated with n-HA and $n-SiO_2$. CONCLUSION: Compared to other groups, PCEC-CS nanofibers incorporated with 15 wt% n-HA were able to support more cell adhesion and differentiation, thus are better candidates for bone tissue engineering applications.

• 폴리머
• /
• 제35권6호
• /
• pp.605-609
• /
• 2011

전기방사법과 열처리 공정을 통하여 PVDF-$SiO_2$ 복합나노섬유를 제조하였으며, 얻어진 나노섬유는 서로 연결된 기공으로 이루어진 적층 구조를 하고 있었다. 즉, 전기방사로 제조된 나노섬유는 직경이 380 nm, 기공도가 80% 이상인 다공성막을 형성하였다. TEM 사진과 EDX 스펙트라의 분석 결과로부터 $SiO_2$가 나노섬유에 균일하게 분산되어 존재한다는 것이 확인되었다. 또한 전기방사법의 도입에 의해 나노섬유의 기공도가 현저히 개선되었다. ATR-FTIR 및 XRD 분석 결과 복합나노섬유 상에서 PVDF는 ${\alpha}$-phase와 ${\beta}$-phase가 혼재되어 있는 결정구조를 가지고 있었으며, 열처리에 의해서 PVDF의 ${\alpha}$-phase가 증가하였으며, 이로 인해 결정화도가 증가하였다. 특히, 기계적 강도, 열적 특성 및 소수성은 열처리 공정에 의해서 매우 증가되는 것을 확인할 수 있었다.

• 폴리머
• /
• 제39권2호
• /
• pp.323-328
• /
• 2015

졸-젤법을 이용한 전기방사법과 캐스팅법으로 폴리(${\varepsilon}$-카프로락톤)(PCL) 나노섬유와 PCL/실리카 막을 각각 제조하였다. 용매에 N,N-dimethylformamide(DMF)를 혼합한 경우 부드럽고 연속적인 PCL 나노섬유가 제조되었다. PCL 기지상에 tetraethyl orthosilicate(TEOS) 농도가 0에서 40 vol%로 증가함에 따라 PCL/silica의 강도는 12에서 8MPa로 감소하였지만, 7주까지 phosphate buffered saline solution(PBS) 침지에 따른 강도값의 변화는 없었다. 실리카 첨가에 따른 인장강도의 감소는 기공도의 증가에 기인하였다. PCL/실리카 막의 결정구조는 사방정계로 실리카 농도가 0에서 40 vol%로 증가함에 따라 crystallite 크기는 57에서 18 nm로 감소하였다. 세포독성 실험결과, PCL/실리카는 시편의 수축 및 변형이 없고, 검체 주위에서 변색이나 L-929 세포의 이상이 관찰되지 않는 무독성이었다.

• Elastomers and Composites
• /
• 제44권1호
• /
• pp.22-33
• /
• 2009

최근에 나노충전제를 낮은 부피 분율로 보강한 엘라스토머-나노복합체는 흥미 있는 물성 때문에 관심을 크게 불러 일으켰다. 특히 층화 규산염 클레이(clay), 카본 나노튜브(carbon nanotube), 나노섬유, 탄산칼슘, 금속 산화물 또는 실리카 나노입자 등과 같은 나노충전제를 탄성체에 혼입하면 기계적 물성, 내열성, 동적 기계적 물성, 화염지연성, 차단성 등이 크게 향상된다. 나노복합체의 물성은 크게 고분자 기질, 나노충전제의 성질과 이들의 혼입 방법에 좌우한다. 탄성체 기질 내에 나노충전제들의 균일한 분산은 원하는 물리적 특성과 기계적 특성을 얻기 위한 일반적 필수조건이다. 본 논문은 층화 규산염, 실리카(silica), 카본 나노튜브(carbon nanotube), 나노섬유와 여러 가지 다른 나노입자로 보강된 탄성체 나노복합체의 현재 개발 현황을 소개하였다.

• 대한의용생체공학회:의공학회지
• /
• 제44권6호
• /
• pp.465-475
• /
• 2023

In this study, we demonstrated a silica nanofibrous membrane based on the electrospinning process and evaluated its DNA isolation and purification performance in PCR pretreatment. Generally, silica membranes made of non-woven fabric are used for PCR pretreatment, but this study aimed to improve the efficiency of the pretreatment process by developing a nanofiber-type silica membrane with high specific surface area and porosity. In order to manufacture a nanofiber-shaped silica film while maintaining the original physical properties of silica, nanofiber membranes produced by adding various concentrations of PEO (5 wt%, 8 wt%, and 10 wt%) to silica prepared by the sol-gel method were compared. In terms of nanofiber membrane production, the higher the PEO concentration, the more effective it was in producing nanofiber membranes. The produced silica nanofiber membrane was inserted to a pretreatment device used in commercial PCR equipment, and the pretreatment performance was compared and verified using Salmonella bacteria. When Salmonella was used, samples containing 5 wt% PEO showed superior PCR efficiency compared to samples containing 8 wt% and 10 wt% PEO. These results show that adding 5 wt% of PEO can effectively improve DNA purification and separation by producing a nanofiber-shaped silica film while maintaining the physical properties of silica. We expect that this study will contribute to the development of effective PCR pretreatment technology essential for various molecular biology applications.

• Korean Chemical Engineering Research
• /
• 제52권5호
• /
• pp.667-671
• /
• 2014

본 연구에서는 전구체 각각의 독립제어가 가능한 이성분계 금속산화물을 얻기 위해 졸-겔법으로 합성한 실리카 나노입자를 $TiO_2$ 전구체와 교반시켜 전기방사법을 이용하여 실리카가 고르게 분산된 $TiO_2$ 나노섬유를 성공적으로 제작하였다. 제작된 나노섬유는 FE-SEM, XRD, EDS를 이용해 구조적 특성분석과 UV-VIS, 광촉매 반응기를 통해 광촉매 특성 분석을 하였다. 그 결과, 실리카가 분산된 $TiO_2$ 나노섬유는 실리카가 분산되지 않은 $TiO_2$ 나노섬유 보다 광촉매 효율이 10% 가량 향상되었다. 이는 실리카 나노입자가 첨가됨으로써 $TiO_2$가 흡수하지 못하는 380~440 nm 가시광선 영역을 흡수하여 광학적 특성 향상되었으며 Ti와 Si 두 금속산화물간에 $Br{\o}nsted$ acid site가 생성되어 OH 라디칼을 증가시킴으로써 광조사에 의해 여기된 전자를 잡아 재결합 손실을 억제하는 역할을 하여 화학적 특성이 개선되어 광촉매 효율이 증가되었을 것으로 사료된다.

• 고무기술
• /
• 제12권1호
• /
• pp.1-7
• /
• 2011

Nanotechnology is the fast becoming key technology of the $21^{st}$ century. Due to its fascinating size-dependent properties, it has gained significant important in various sectors. Myths are being formed on the proverbal nanotechnology market, but the reality is the nanotechnology is not a market but a value chain. The chain comprises of - nanomaterials (nanoparticles) and nanointermediates (coatings, compounds, smart fabrics). Elastomer based nanocomposites reinforced with low volume fraction of nanofillers is the first generation nanotechnology products and it has attracted great interest due to their fascinating properties. The incorporation of nanofillers such as nanolayered silicates, carbon nanotubes, nanofibers, metal oxides or silica nanoparticles into elastomers improves significantly their mechanical, thermal, barrier properties, flame retardency etc., Extremely small particle size, high aspect ratio and large interface area yield an excellent improvement of the properties in a wide variety of the materials. Uniform dispersion of the nanofillers is a general prerequisite for achieving desired properties. In this paper, current developments in the area of elastomer based nanocomposites reinforced with layered silicate and carbon nanotube fillers are highlighted.