• Bulletin of the Korean Chemical Society
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• 제32권6호
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• pp.2051-2057
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• 2011

Several studies have demonstrated that nanoparticles (NPs) have toxic effects on cultured cell lines, yet there are no clear data describing the overall molecular changes induced by NPs currently in use for human applications. In this study, the in vitro cytotoxicity of three oxide NPs of around 100 nm size, namely, mesoporous silica (MCM-41), iron oxide ($Fe_2O_3$-NPs), and zinc oxide (ZnO-NPs), was evaluated in the human embryonic kidney cell line HEK293. Cell viability assays demonstrated that 100 ${\mu}g/mL$ MCM-41, 100 ${\mu}g/mL$ $Fe_2O_3$, and 12.5 ${\mu}g/mL$ ZnO exhibited 20% reductions in HEK293 cell viability in 24 hrs. DNA microarray analysis was performed on cells treated with these oxide NPs and further validated by real time PCR to understand cytotoxic changes occurring at the molecular level. Microarray analysis of NP-treated cells identified a number of up- and down-regulated genes that were found to be associated with inflammation, stress, and the cell death and defense response. At both the cellular and molecular levels, the toxicity was observed in the following order: ZnO-NPs > $Fe_2O_3$-NPs > MCM-41. In conclusion, our study provides important information regarding the toxicity of these three commonly used oxide NPs, which should be useful in future biomedical applications of these nanoparticles.

• 멤브레인
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• 제28권4호
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• pp.265-270
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• 2018

이전 연구에서 올레핀/파라핀 분리를 위해 poly(ethylene oxide)(PEO)/Ag nanoparicles (AgNPs)(전구체$AgBF_4$)/p-benzoquinone (p-BQ) 복합막이 제조되었으며, 이 복합체 분리막의 성능은 100시간까지 선택도 10과 투과도 15 GPU로 유지되는 것이 확인되었다. 하지만 전구체인 $AgBF_4$의 가격이 고가이기 때문에, 본 연구에서는 가격 측면에서 경쟁력이 있는 $AgNO_3$를 Ag nanoparticles의 전구체로 사용하여 실험을 진행하였다. 그 결과 이미 존재하고 있는 $NO_3{^-}$가 AgNPs를 감싸고 있기 때문에 분리 성능이 나오지 않는 것으로 관찰되었다. 이번 연구에서는 $AgNO_3$를 Ag nanoparticles의 전구체로 사용하여도 높은 성능을 내기 위해 전자수용체 7,7,8,8-tetracyanoquinodimethane (TCNQ)를 사용하여 PEO, polyvinyl alcohol (PVA), polyether block amide-1657 (PEBAX-1657) 고분자 복합막을 제조한 결과, 고분자와 전자수용체의 영향과는 무관하게 분리성능을 내지 못하는 것으로 분석되었으며, 이는 분리성능에 전구체의 음이온이 결정적 역할을 하는 것으로 분석되었다.

• 대한수의학회지
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• 제57권2호
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• pp.105-111
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• 2017

Hyaluronic acid (HA) has been investigated for biomedical and pharmaceutical applications. This study was conducted to determine the distributions of HA nanoparticles (NPs; size 350-400 nm) and larger HA polymers in mice at intervals after application. $^{177}Lutetium$ (Lu)-labeled HA-NPs or HA polymers were intravenously injected (5 mg/kg) into male ICR mice, and radioactivity levels in blood and target organs were measured from 0.25 h to 28 days post-injection. In blood, the radioactivities of HA-NPs and HA polymer peaked at 0.5 h after injection but were remarkably decreased at 2 h; subsequently, they maintained a constant level until 6 days post-injection. HA-NPs and HA polymers were observed in the liver, spleen, lung, kidney, and heart (in ascending order) but were seldom observed in other organs. After 3 days, both the HA-NP and HA polymer levels showed similar steady decreases in lung, kidney, and heart. However, in liver and spleen, the HA-NP levels tended to decrease gradually after 1 day and both were very low after 14 days, whereas the HA polymer level accumulated for 28 days. The results indicate that HA-NPs, with their faster clearance pattern, may act as a better drug delivery system than HA polymers, especially in the liver and spleen.

• Korean Chemical Engineering Research
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• 제46권2호
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• pp.330-339
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• 2008

본 연구에서는 비이온 계면활성제, 보조계면활성제 등의 첨가제가 AOT 계면활성제 시스템의 water-in-oil(W/O) 마이크로에멀젼을 이용한 AgCl 나노입자 제조에 미치는 영향에 관하여 살펴보았다. AOT 계면활성제, isooctane, 무기염 수용액으로 이루어진 삼성분 시스템에 NP 계열 비이온 계면활성제를 첨가한 결과, 단일상으로 존재하는 W/O 마이크로에멀젼 영역은 증가하였으며, 일반적으로 첨가한 비이온 계면활성제의 친수성이 증가할수록 단일상의 영역은 증가하였다. 또한 첨가한 비이온 계면활성제는 마이셀의 계면을 보다 유연하게 함으로써 생성된 입자의 크기는 증가하고 분포도는 넓어졌다. 한편 보조계면활성제로 알코올을 첨가하면서 상평형 실험을 수행한 결과, 알코올의 사슬 길이가 증가하거나 첨가량이 증가할수록 단일상으로 존재하는 W/O 마이크로에멀젼이 보다 좁은 영역에서 형성되었다. 상평형 실험결과에 의하여 결정된 단일상의 W/O 마이크로에멀젼 영역 내에 해당하는 조건에서 보조계면활성제의 사슬 길이와 첨가량을 변화시키면서 AgCl 나노입자 제조실험을 수행한 결과, 생성된 AgCl 입자의 특성은 보조계면활성제 첨가에 따른 마이크로에멀젼의 radius of spontaneous curvature와 필름 rigidity의 변화에 의하여 결정됨을 알 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.71-71
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• 2011

Dye-sensitized solar cells (DSCs) have drawn great academic attention due to their potential as low-cost renewable energy sources. DSCs contain a nanostructured TiO2 photoanode, which is a key-component for high conversion efficiency. Particularly, one-dimensional (1-D) nanostructured photoanodes can enhance the electron transport for the efficient collection to the conducting substrate in competition with the recombination processes. This is because photoelectron colletion is determined by trapping/detrapping events along the site of the electron traps (defects, surface states, grain boundaries, and self-trapping). Therefore, 1-D nanostructured photoanodes are advantageous for the fast electron transport due to their desirable features of greatly reduced intercrystalline contacts with specified directionality. In particular, anodic TiO2 nanotube (NT) electrodes recently have been intensively explored owing to their ideal structure for application in DSCs. Besides the enhanced electron transport properties resulted from the 1-D structure, highly ordered and vertically oriented nanostructure of anodic TiO2 NT can contribute additional merits, such as enhanced electrolyte diffusion, better interfacial contact with viscous electrolytes. First, to confirm the advantages of 1-D nanostructured material for the photoelectron collection, we compared the electron transport and charge recombination characteristics between nanoparticle (NP)- and nanorod (NR)-based photoanodes in DSCs by the stepped light-induced transient measurements of photocurrent and voltage (SLIM-PCV). We confirmed that the electron lifetime of the NR-based photoanode was much longer than that of the NP-based photoanode. In addition, highly ordered and vertically oriented TiO2 NT photoanodes were prepared by electrochemical anodization method. We compared the photovoltaic properties of DSCs utilizing TiO2 NT photoanodes prepared by one-step anodization and two-step anodization. And, to reduce the charge recombination rate, energy barrier layer (ZnO, Al2O3)-coated TiO2 NTs also applied in DSC. Furthermore, we applied the TiO2 NT photoanode in DSCs using a viscous electrolyte, i.e., cobalt bipyridyl redox electrolyte, and confirmed that the pore structure of NT array can enhance the performances of this viscous electrolyte.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.411-411
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• 2012

Over the recent years, surface enhanced Raman spectroscopy (SERS) has dramatically grown as a label-free detecting technique with the high level of selectivity and sensitivity. Conventional SERS-active nanostructured layers have been deposited or patterned on rigid substrates such as silicon wafers and glass slides. Such devices fabricated on a flexible platform may offer additional functionalities and potential applications. For example, flexible SERS-active substrates can be integrated into microfluidic diagnostic devices with round-shaped micro-channel, which has large surface area compared to the area of flat SERS-active substrates so that we may anticipate high sensitivity in a conformable device form. We demonstrate fabrication of flexible SERS-active nanostructured substrates based on soft-lithography for simple, low-cost processing. The SERS-active nanostructured substrates are fabricated using conventional Si fabrication process and inkjet printing methods. A Si mold is patterned by photolithography with an average height of 700 nm and an average pitch of 200 nm. Polydimethylsiloxane (PDMS), a mixture of Sylgard 184 elastomer and curing agnet (wt/wt = 10:1), is poured onto the mold that is coated with trichlorosilane for separating the PDMS easily from the mold. Then, the nano-pattern is transferred to the thin PDMS substrates. The soft lithographic methods enable the SERS-active nanostructured substrates to be repeatedly replicated. Silver layer is physically deposited on the PDMS. Then, gold nanoparticle (AuNP) inks are applied on the nanostructured PDMS using inkjet printer (Dimatix DMP 2831) to deposit AuNPs on the substrates. The characteristics of SERS-active substrates are measured; topology is provided by atomic force microscope (AFM, Park Systems XE-100) and Raman spectra are collected by Raman spectroscopy (Horiba LabRAM ARAMIS Spectrometer). We anticipate that the results may open up various possibilities of applying flexible platform to highly sensitive Raman detection.

• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.913-918
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• 2014

Five mol % tungsten-doped tin oxide ($W_{0.05}Sn_{0.95}O_2$, TTO5) was prepared by co-precipitation of $SnCl_4{\cdot}5H_2O$ and $WCl_4$, followed by calcination at $1000^{\circ}C$. The as-prepared TTO5 was in the pure cassiterite phase with a particle size of ~50 nm and optical bandgap of 2.51 eV. Herein it was applied for the formation of TTO5/$TiO_2$ heterojunctions by covering the TTO5 surface with $TiO_2$ by sol-gel method. Under visible-light irradiation (${\lambda}{\geq}420$ nm), TTO5/$TiO_2$ showed a significantly high photocatalytic activity in removing gaseous 2-propanol (IP) and evolving $CO_2$. It is deduced that its high visible-light activity is caused by inter-semiconductor holetransfer between the valence band (VB) of TTO5 and $TiO_2$, since the TTO5 nanoparticle (NP) exhibits the absorption edge at ~450 nm and its VB level is located more positive side than that of $TiO_2$. The evidence for the hole-transport mechanism between TTO5 and $TiO_2$ was also investigated by monitoring the holescavenging reaction with 1,4-terephthalic acid (TA).

• Asian Pacific Journal of Cancer Prevention
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• 제15권24호
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• pp.10705-10711
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• 2015

Oral cancer is one of the most common and lethal cancers in the world. Combination chemotherapy coupled with nanoparticle drug delivery holds substantial promise in cancer therapy. This study aimed to evaluate the efficacy and safety of two dosages of our novel pH and temperature sensitive doxorubicin-methotrexate-loaded nanoparticles (DOX-MTX NPs) with attention to the MMP-2 mRNA profile in a 4-nitroquinoline-1-oxide induced oral squamous cell carcinoma (OSCC) model in the rat. Our results showed that both IV and oral dosages of DOX-MTX NP caused significant decrease in mRNA levels of MMP-2 compared to the untreated group (p<0.003). Surprisingly, MMP-2 mRNA was not affected in DOX treated compared to cancer group (p>0.05). Our results indicated that IV dosage of MTX-DOX is more effective than free DOX (12 fold) in inhibiting the activity of MMP-2 in OSCCs (P<0.001). Furthermore, MMP-2 mRNA expression in the DOX-MTX treated group showed a significant relation with histopathological changes (P=0.011). Compared to the untreated cancer group, we observed no pathological changes and neither a significant alteration in MMP-2 amount in either of healthy controls that were treated with oral and IV dosages of DOX-MTX NPs whilst cancer group showed a high level of MMP-2 expression compared to healthy controls (p<0.001).Taking together our results indicate that DOX-MTX NPs is a safe chemotherapeutic nanodrug that its oral and IV forms possess potent anti-cancer properties on aggressive tumors like OSCC, possibly by affecting the expression of genes that drive tumor invasion and metastasis.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.278.1-278.1
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• 2014

Organic materials have been explored as the gate dielectric layers in thin film transistors (TFTs) of backplane devices for flexible display because of their inherent mechanical flexibility. However, those materials possess some disadvantages like low dielectric constant and thermal resistance, which might lead to high power consumption and instability. On the other hand, inorganic gate dielectrics show high dielectric constant despite their brittle property. In order to maintain advantages of both materials, it is essential to develop the alternative materials. In this work, we manufactured nanocomposite gate dielectrics composed of organic material and inorganic nanoparticle and integrated them into organic TFTs. For synthesis of nanocomposite gate dielectrics, polyimide (PI) was explored as the organic materials due to its superior thermal stability. Candidate nanoprticles (NPs) of halfnium oxide, titanium oxide and aluminium oxide were considered. In order to realize NP concentration dependent electrical characteristics, furthermore, we have synthesized the different types of nanocomposite gate dielectrics with varying ratio of each inorganic NPs. To analyze gate dielectric properties like the capacitance, metal-Insulator-metal (MIM) structures were prepared together with organic TFTs. The output and transfer characteristics of organic TFTs were monitored by using the semiconductor parameter analyzer (HP4145B), and capacitance and leakage current of MIM structures were measured by the LCR meter (B1500, Agilent). Effects of mechanical cyclic bending of 200,000 times and thermally heating at $400^{\circ}C$ for 1 hour were investigated to analyze mechanical and thermal stability of nanocomposite gate dielectrics. The results will be discussed in detail.

• 한국분말재료학회지
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• 제23권2호
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• pp.95-101
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• 2016

Carbon nanofiber (CNF) composites coated with spindle-shaped $Fe_2O_3$ nanoparticles (NPs) are fabricated by a combination of an electrospinning method and a hydrothermal method, and their morphological, structural, and chemical properties are measured by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. For comparison, CNFs and spindle-shaped $Fe_2O_3$ NPs are prepared by either an electrospinning method or a hydrothermal method, respectively. Dye-sensitized solar cells (DSSCs) fabricated with the composites exhibit enhanced open circuit voltage (0.70 V), short-circuit current density ($12.82mA/cm^2$), fill factor (61.30%), and power conversion efficiency (5.52%) compared to those of the CNFs (0.66 V, $11.61mA/cm^2$, 51.96%, and 3.97%) and spindle-shaped $Fe_2O_3$ NPs (0.67 V, $11.45mA/cm^2$, 50.17%, and 3.86%). This performance improvement can be attributed to a synergistic effect of a superb catalytic reaction of spindle-shaped $Fe_2O_3$ NPs and efficient charge transfer relative to the one-dimensional nanostructure of the CNFs. Therefore, spindle-shaped $Fe_2O_3$-NP-coated CNF composites may be proposed as a potential alternative material for low-cost counter electrodes in DSSCs.