• Smart Structures and Systems
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• 제8권5호
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• pp.471-486
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• 2011

Various types of strain sensors have been developed and widely used in the field for monitoring the mechanical deformation of structures. However, conventional strain sensors are not suited for measuring large strains associated with impact damage and local crack propagation. In addition, strain sensors are resistive-type transducers, which mean that the sensors require an external electrical or power source. In this study, a gold nanoparticle (GNP)-based polymer composite is proposed for large strain sensing. Fabrication of the composites relies on a novel and simple in situ GNP reduction technique that is performed directly within the elastomeric poly(dimethyl siloxane) (PDMS) matrix. First, the reducing and stabilizing capacities of PDMS constituents and mixtures are evaluated via visual observation, ultraviolet-visible (UV-Vis) spectroscopy, and transmission electron microscopy. The large strain sensing capacity of the GNP-PDMS thin film is then validated by correlating changes in thin film optical properties (e.g., maximum UV-Vis light absorption) with applied tensile strains. Also, the composite's strain sensing performance (e.g., sensitivity and sensing range) is also characterized with respect to gold chloride concentrations within the PDMS mixture.

• Bulletin of the Korean Chemical Society
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• 제32권spc8호
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• pp.2941-2948
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• 2011

A nanogap formed by a metal nanoparticle and a flat metal substrate is one kind of "hot site" for surface-enhanced Raman scattering (SERS). The characteristics of a typical nanogap formed by a planar Au and either an Au and Ag nanoparticle have been well studied using 4-aminobenzenethiol (4-ABT) as a probe. 4-ABT is, however, an unusual molecule in the sense that its SERS spectral feature is dependent not only on the kinds of SERS substrates but also on the measurement conditions; thus further characterization is required using other adsorbate molecules such as 1,4-phenylenediisocyanide (1,4-PDI). In fact, no Raman signal was observable when 1,4-PDI was selfassembled on a flat Au substrate, but a distinct spectrum was obtained when 60 nm-sized Au or Ag nanoparticles were adsorbed on the pendent -NC groups of 1,4-PDI. This is definitely due to the electromagnetic coupling between the localized surface plasmon of Au or Ag nanoparticle with the surface plasmon polariton of the planar Au substrate, allowing an intense electric field to be induced in the gap between them. A higher Raman signal was observed when Ag nanoparticles were attached to 1,4-PDI, irrespective of the excitation wavelength, and especially the highest Raman signal was measured at the 632.8 nm excitation (with the enhancement factor on the order of ${\sim}10^3$), followed by the excitation at 568 and 514.5 nm, in agreement with the finite-difference timedomain calculation. From a separate potential-dependent SERS study, the voltage applied to the planar Au appeared to be transmitted without loss to the Au or Ag nanoparticles, and from the study of the effect of volatile organics, the voltage transmission from Au or Ag nanoparticles to the planar Au also appeared as equally probable to that from the planar Au to the Au or Ag nanoparticles in a nanogap electrode. The response of the Au-Ag nanogap to the external stimuli was, however, not the same as that of the Au-Au nanogap.

• Biomolecules & Therapeutics
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• 제17권1호
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• pp.92-97
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• 2009

As nanomaterials might enter into cells and have high reactivity with intracellular structures, it is necessary to assay possible genotoxic risk of them. One of these approaches, we investigated possible genotoxic potential of gold nanoparticle (AuNP) using L5178Y cells. Four different sizes of AuNP (4, 15, 100 or 200 nm) were synthesized and the sizes and structures of AuNP were analyzed using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and stability was analyzed by a UV/Vis. Spectrophotometer. Cytotoxicity was assessed by direct cell counting, and cellular location was detected by dark field microscope at 6, 24 and 48 h after treatment of AuNP. Comet assay was conducted to examine DNA damage and tumor necrosis factor (TNF)-${\alpha}$ mRNA level was assay by real-time reverse transcription polymerase chain reaction. Synthetic AuNP (4, 50, 100 and 200 nm size) had constant characteristics and stability confirmed by TEM, SEM and spectrophotometer for 10 days, respectively. Dark field microscope revealed the location of AuNP in the cytoplasm at 6, 24 and 48 h. Treatment of 4 nm AuNP induced dose and time dependent cytotoxicity, while other sizes of AuNP did not. However, Comet assay represented that treatment of 100 nm and 200 nm AuNP significantly increased DNA damage compared to vehicle control (p <0.01). Treatment of 100 nm and 200 nm AuNP significantly increased TNF-${\alpha}$ mRNA expression compared to vehicle control (p<0.05, p<0.01, respectively). Taken together, AuNP induced DNA damage in L5178Y cell, associated with induction of oxidative stress.

• 한국식품위생안전성학회지
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• 제34권3호
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• pp.269-276
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• 2019

본 연구에서는 시판되고 있는 혈청 내 AChE가 acetylthiocholine과 반응하여 GNP에 aggregation 일으키는 원리를 이용하여 신선채소 농산물 중에 저농도 농약을 신속하고 간편하게 분석할 수 있는 비색-신속 농약 검출법을 개발하는 연구를 수행하였다. 먼저 비색-신속 농약 검출법의 최적화를 위해 GNP 입자의 크기에 따른 응집정도를 확인하여 15~20 nm 직경의 GNP를 선정하였고, 혈청의 희석배수와 acetylthiocholine의 농도를 확인하여 GNP 응집 차이가 가장 큰 혈청 1000배 희석과 acetylthiocholine 1 mM을 최적화 조건으로 선정하였다. 비색-신속 농약 검출법의 평가를 위해 최적화된 비색농약분석법을 이용하여 유기인계 농약은 dimethyl amine으로 카바메이트계 농약은 carbofuran으로 민감도를 분석한 결과 모두 7.5 ng/mL까지 검출이 가능한 것으로 확인되었으며 이는 기존의 비색-신속 농약 검출법과 비교했을 때 높은 민감도와 특이성을 나타내었다. 농약 이외에 화학물질인 곰팡이독소 등에 대한 반응성은 확인되지 않아 높은 특이성을 나타내었다. 또한 상추, 깻잎, 양상추에 대한 시료 전처리법을 확립하고 임의로 오염시킨 3종(상추, 깻잎, 양상추)의 농산물에 대해서 회수율을 확인한 결과유기인계와 카바메이트계 농약을 83.85~133.16% 정도의 회수율이 확인되었다. 이상의 결과 볼 때 본 연구에서 개발한 비색-신속 농약 검출법을 이용한다면 시판 농산물의 잔류농약을 신속하고 민감도 높게 검출할 수 있을 것으로 판단된다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권1호
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• pp.169-174
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• 2015

Cervical cancer (CxCa) is the most common cancer in women and a prominent cause of cancer mortality worldwide. The primary cause of CxCa is human papillomavirus (HPV). Radiation therapy and chemotherapy have been used as standard treatments, but they have undesirable side effects for patients. It was reported that gallic acid has antioxidant, antimicrobial, and anticancer activities. Gold nanoparticles are currently being used in medicine as biosensors and drug delivery agents. This study aimed to develop a drug delivery agent using gold nanoparticles conjugated with gallic acid. The study was performed in uninfected (C33A) cervical cancer cells, cervical cancer cells infected with HPV type 16 (CaSki) or 18 (HeLa), and normal Vero kidney cells. The results showed that GA inhibited the proliferation of cancer cells by inducing apoptosis. To enhance the efficacy of this anticancer activity, 15-nm spherical gold nanoparticles (GNPs) were used to deliver GA to cancer cells. The GNPs-GA complex had a reduced ability compared to unmodified GA to inhibit the growth of CxCa cells. It was interesting that high-concentration ($150{\mu}M$) GNPs-GA was not toxic to normal cells, whereas GA alone was cytotoxic. In conclusion, GNPs-GA could inhibit CxCa cell proliferation less efficiently than GA, but it was not cytotoxic to normal cells. Thus, gold nanoparticles have the potential to be used as phytochemical delivery agents for alternative cancer treatment to reduce the side effects of radiotherapy and chemotherapy.

• 공업화학
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• 제32권2호
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• pp.163-167
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• 2021

본 연구에서는 타이로신이 풍부한 펩타이드, Tyr-Tyr-Leu-Tyr-Tyr (YYLYY)를 이용하여 금 나노입자를 담지한 균일한 금-펩타이드 계층적 초분자 구조체의 합성에 대해 연구하였다. 펩타이드의 광가교 반응을 통해 다이타이로신 결합으로 자기조립된 펩타이드 나노입자를 합성하였고, 타이로신의 생체 광물화 특성을 이용하여 금-펩타이드 하이브리드 나노입자를 친환경적 방법으로 합성하였다. 합성된 금-펩타이드 하이브리드 나노입자는 투과 전자 현미경(TEM), 주사투과 전자 현미경(SEM), 동적 광산란(DLS), 자외선-가시광선 분광광도계(UV-Vis spectroscopy), 에너지 분산 X선 분광법(STEM-EDS), X선 회절 분석법(XRD)을 통해 분석하였다. 또한 합성된 금-펩타이드 하이브리드 나노입자는 메틸렌블루의 환원 반응에서 13.4 × 10-3 s-1의 반응속도 상수를 가지는 촉매 특성을 확인하였다.

• Advances in nano research
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• 제10권3호
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• pp.295-312
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• 2021

A new ionic liquid functionalized magnetic silica nanoparticle was synthesized and characterized and tested as an adsorbent. The adsorbent was used for magnetic solid phase extraction on ICP-MS method. Simultaneous determination of precious metal Au has been addressed. The method is simple and fast and has been applied to standard water and surface water analysis. A new method for separation/analysis of trace precious metal Au by Magnetron Solid Phase Extraction (MSPE) combined with ICP-MS. The element to be tested is rapidly adsorbed on CoFe2O4@SiO2@[BMIM]PF6 composite nano-adsorbent and eluted with thiourea. The method has a preconcentration factor of 9.5-fold. This method has been successfully applied to the determination of gold in actual water samples. Hydrophobic Ionic Liquids (ILs) 1-butyl-3-methylimidazole hexafluorophosphate ([BMIM]PF6) coated CoFe2O4@SiO2 nanoparticles with core-shell structure to prepare magnetic solid phase extraction agent (CoFe2O4@SiO2@ILs) and establish a new method of MSPE coupled with inductively coupled plasma mass spectrometry for separation/analysis of trace gold. The results showed that trace gold was adsorbed rapidly by CoFe2O4@SiO2@[BMIM]PF6 and eluanted by thiourea. Under the optimal conditions, preconcentration factor of the proposed method was 9.5-fold. The linear range, detection limit, correlation coefficient (R) and relative standard deviation (RSD) were found to be 0.01~1000.00 ng·mL-1, 0.001 ng·mL-1, 0.9990 and 3.4% (n = 11, c = 4.5 ng·mL-1). The CoFe2O4@SiO2 nanoparticles could be used repeatedly for 8 times. This proposed method has been successfully applied to the determination of trace gold in water samples.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.243-243
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• 2009

Bi2O3 doped ZnO nanostructures structure were successfully synthesized by a thermal evaporatiion process and their structural characteristics were investigated. It is demonstrated that the growth condition such as the areal density, pretreatment of the substrates and growth temperature have great influence on the morphology and the alignment of the nanorods arrays. The density of Bi2O3 doped ZnO nanostructures is controlled by the gold (Au) nanoparticle density deposited on the silicon substrates. Relatively homogenous size and shape were observed by introducing gold(Au) seed-layer as nucleation centers on the substrates prior to the VLS reaction. The samples were characterized by X-ray diffraction, scanning electron microscopy.

• Advances in nano research
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• 제2권3호
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• pp.135-145
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• 2014

Nanomaterials synthesized by natural bioresources such as microorganisms, animals and plants in nature can also be synthesized in laboratories even on large scale. This is considered as an attractive prospect for eco-friendly or so-called green synthesis. Development of eco-friendly synthesis of biocompatible nanoparticles and their potential biomedical applications introduces the concept of nanobiotechnology. The lower cost and lesser side effects as compare to chemical methods of synthesis are the main advantages of biosynthesis. This review article demonstrates the role of various biological resources e.g. bacteria, fungi, actinomycetes, plant leaves, fruits and honey as well as animal tissues for the synthesis of nanoparticles mainly gold and silver with an overview of their potential applications.

• Bulletin of the Korean Chemical Society
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• 제29권1호
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• pp.69-75
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• 2008

Tautomerism of pyrimidine base cytosine has been comparatively examined on nanoparticle and roughened plate surfaces of silver, gold, and copper by surface-enhanced Raman scattering (SERS). The SERS spectrum was found to be different depending on the metals and their substrate conditions suggesting the dissimilar population of various tautomers of cytosine on the surfaces. The ab initio calculations were performed at the levels of B3LYP, HF, and MP2 levels of theory with the LanL2DZ basis set to estimate the energetic stability of the tautomers with the metal complexes as well as the gas phase state. The amino group and N3-coordinated tautomer was predicted to be more favorable for bonding to Au, whereas the hydroxyl and N1-coordinated zwitter ionic form is most stable with Ag and Cu as a bidentate form from the DFT calculation. The binding energy with the Ag atom is calculated to be smaller than those with the Au and Cu atoms in line with the temperature-dependent SERS spectra of cytosine.