• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.30-34
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• 2014

We report a novel approach for fabricating active surface-enhanced Raman scattering (SERS) substrate for sensitive detection. This approach is based on the assembling of gold nanoparticles (AuNPs) onto the electrospun polycaprolactone (PCL) nanofiber film. The hydrophobic surface of PCL nanofiber film was pretreated using UV-inducing graft polymerization with acrylic acid. Afterwards this PCL nanofiber film was incubated with the AuNP solution to promote the assembly of AuNPs onto the PCL nanofibers and the formation of SERS active substrate. 4-aminothiophenol (4-ATP) molecule was used as a test probe for SERS experiments, indicating that the substrate has high sensitivity to SERS response. Our method has great advantage in term of environment-friendly synthesis, large-scale, high stability and good reproducibility. This highly active SERS substrate can be employed to detect the drug molecule, 2-thiouracil.

• Advances in nano research
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• v.13 no.5
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• pp.417-426
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• 2022

Bisphenol A (BPA) is one of the chemicals used in monomer epoxy resins and polycarbonate plastics. The surface-enhanced Raman spectroscopy (SERS) method is precise for identifying biological materials and chemicals at considerably low concentrations. In the present article, the substrates coated with gold nanoparticles have been studied to identify BPA and control the diseases caused by this chemical. Gold nanoparticles were made by a simple chemical method and by applying gold salt and trisodium citrate dihydrate reductant and were coated on glass substrates by a spin-coat approach. Finally, using these SERS substrates as plasmonic sensors and Raman spectroscopy, the Raman signal enhancement of molecular vibrations of BPA was investigated. Then, the molecular vibrations of BPA in some consumer goods were identified by applying SERS substrates as plasmonic sensors and Raman spectroscopy. The fabricated gold nanoparticles are spherical and quasi-spherical nanoparticles that confirm the formation of gold nanoparticles by observing the plasmon resonance peak at 517 nm. Active SERS substrates have been coated with nanoparticles, which improve the Raman signal. The enhancement of the Raman signal is due to the resonance of the surface plasmons of the nanoparticles. Active SERS substrates, gold nanoparticles deposited on a glass substrate, were fabricated for the detection of BPA; a detection limit of 10-9 M and a relative standard deviation (RSD) equal to 4.17% were obtained for ten repeated measurements in the concentration of 10-9 M. Hence, the Raman results indicate that the active SERS substrates, gold nanoparticles for the detection of BPA along with the developed methods, show promising results for SERS-based studies and can lead to the development of microsensors. In Raman spectroscopy, SERS active substrate coated with gold nanoparticles are of interest, which is larger than gold particles due to the resonance of the surface plasmons of gold nanoparticles and the scattering of light from gold particles since the Raman signal amplifies the molecular vibrations of BPA. By decreasing the concentration of BPA deposited on the active SERS substrates, the Raman signal is also weakened due to the reduction of molecular vibrations. By increasing the surface roughness of the active SERS substrates, the Raman signal can be enhanced due to increased light scattering from rough centers, which are the same as the larger particles created throughout the deposition by the spin-coat method, and as a result, they enhance the signal by increasing the scattering of light. Then, the molecular vibrations of BPA were identified in some consumer goods by SERS substrates as plasmonic sensors and Raman spectroscopy.

• Advances in nano research
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• v.9 no.2
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• pp.113-122
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• 2020

Surface-Enhanced Raman Scattering (SERS) spectroscopy is a multifaceted surface sensitive methodology which exploits spectroscopy-based analysis for various applications. This technique is based on the massive amplification of Raman signals which were feeble previously in order to use them for appropriate identification at qualitative and quantitative in chemical as well as biological systems. This novel powerful technique can be utilized to identify pathogens such as bacteria and viruses. As far as SERS is concerned, one of the most studied problems has been functionalization of SERS active substrate. Metal colloids and nanostructures or microstructures synthesized using noble metals such as Au, Ag and Cu are considered to be SERS active. Silver and gold are extensively used as SERS active substrates due to chemical inertness and stability in air compare to copper. However, use of Cu as a suitable alternative has been taken into account as it is cheap. Herein, we have synthesized air-stable copper microstructures/nanostructures by chemical, electrochemical and microwave-assisted methods. In this paper, we have also discussed the use of as synthesized copper micro/nanostructures as inexpensive yet effective SERS active substrates for the fast identification of micro-organisms like Staphylococcus aureus and Escherichia coli.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.443-446
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• 2013

In this work, a novel strategy is provided to prepare silver nanoplates by a fibronectin (Fn) nanofibril template. First, Fn molecules were controlled to assemble into amyloid-like nanofibrils in highly concentrated ethanol aqueous solution. The resultant nanofibrils could serve as a soft template to direct the formation of silver nanoplates. It is worth noting that the silver nanoplates are excellent surface-enhanced Raman scattering (SERS) substrate with 4-aminothiophenol (4-ATP) molecule as a test probe. This high active SERS substrate can also be used to detect drug molecule, 2-thiouracil with high sensitivity.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.83-83
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• 2018

최근 의료, 보건, 헬스케어 분야에 대한 관심이 증가함에 따라 질병의 조기 진단 연구가 각광 받고 있다. 특히 표면증강 라만 산란 (Surface Enhancement Raman scattering)은 고분자 검출을 위해 가장 유용한 물리 화학적 기법으로 SERS를 활용한 특정물질 검출 기술 개발에 대한 연구가 많이 이루어지고 있다. 나노구조의 국부적 표면 플라즈몬의 공명조건 (Surface Plasmon Resonance, SPR)으로 유도된 전자기장은 우수한 SERS 신호를 나타낸다. 따라서 표면 플라즈몬 공명 효과는 귀금속 나노입자의 종류, 크기 및 형태, 기판의 형상 및 구조 등에 의해서 달라지게 되므로 이들을 조절하여 보다 민감한 SERS 신호를 얻을 수 있다. 본 연구에서는 고감도 SERS-Active 기판을 제작하기 위해 SERS 기판 표면의 나노구조를 최적화 하였다. SERS 기판 표면을 제어하기 위해 공정파워, 공정압력, 기판의 온도 등의 증착공정 변수에 변화를 주어 표면의 나노구조를 형성하였다. 이를 분석하기 위해 SEM 분석을 통해 피라미드형 실리콘 기판 표면의 Au 나노구조 금속 박막을 확인하였고, XRD를 이용하여 결정성 및 결정크기를 확인하였다. Rhodamine 6G를 이용한 라만 분석을 통해 SERS 신호의 강도를 알 수 있었다. 금속 나노구조의 형태, 온도 제어를 통해 SERS 신호강도가 우수한 나노구조 기판을 제조 할 수 있었다.

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.445-449
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• 2008

Micrometer-sized copper (mCu) powders are weakly surface-enhanced Raman scattering (SERS) active by the excitation at 632.8 nm, but nearly ineffective as a SERS substrate at 514.5 nm excitation. The SERS activity of mCu powders at both excitation wavelengths can be increased dramatically by a simple method of the galvanic exchange reaction with AgNO3 in aqueous medium. In this work, the SERS activity of the Ag-exchanged Cu powders (mCu@Ag) has been evaluated by taking a series of Raman spectra using benzenethiol (BT) as the probe molecule. It is clearly confirmed by field emission scanning electron microscopy and X-ray diffractometry that the SERS activity of mCu@Ag powders is, in fact, highly dependent on the extent of galvanic reaction.

• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1599-1604
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• 2003

New methods were developed to prepare silver-doped sol-gel films for surface-enhanced Raman spectroscopy (SERS) applications. First, silver ions were doped into a sol-gel matrix. The doped silver ions were reduced into corresponding silver metal particles by two reductive procedures; chemical reduction and thermal reduction. The SERS spectra of benzoic acid were used to demonstrate the SERS effect of the new substrates. The adsorption strength of benzoic acid adsorbed on differently reduced substrates was discussed. The possible adsorption form and the orientation of adsorbate were also discussed.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.743-748
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• 2014

In this work, we describe a very simple electroless deposition method to prepare moderate-SERS-active nanostructured Pd films deposited on the glass substrates. To the best of our knowledge, this is the first report on the one-pot electroless method to deposit Pd nanostructures on the glass substrates. This method only requires the incubation of negatively charged glass substrates in ethanol-water mixture solutions of $Pd(NO_3)_2$ and butylamine at elevated temperatures. Pd films are then formed exclusively and evenly on glass substrates. Due to the aggregated structures of Pd, the SERS spectra of benzenethiol and organic isonitrile could be clearly identified using the Pd-coated glass as a SERS substrate. This one-step fabrication method of Pd thin film on glass is cost-effective and suitable for the mass production.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.393-393
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• 2012

Optically active nanostructures such as subwavelength moth-eye antireflective structures or surface enhanced Raman spectroscopy (SERS) active structures have been demonstrated to provide the effective suppression of unwanted reflections as in subwavelength structure (SWS) or effective enhancement of selective signals as in SERS. While various nanopatterning techniques such as photolithography, electron-beam lithography, wafer level nanoimprinting lithography, and interference lithography can be employed to fabricate these nanostructures, roll-to-roll (R2R) nanoimprinting is gaining interests due to its low cost, continuous, and scalable process. R2R nanoimprinting requires a master to produce a stamp that can be wrapped around a quartz roller for repeated nanoimprinting process. Among many possibilities, two different types of mask can be employed to fabricate optically active nanostructures. One is self-assembled Au nanoparticles on Si substrate by depositing Au film with sputtering followed by annealing process. The other is monolayer silica particles dissolved in ethanol spread on the wafer by spin-coating method. The process is optimized by considering the density of Au and silica nano particles, depth and shape of the patterns. The depth of the pattern can be controlled with dry etch process using reactive ion etching (RIE) with the mixture of SF6 and CHF3. The resultant nanostructures are characterized for their reflectance using UV-Vis-NIR spectrophotometer (Agilent technology, Cary 5000) and for surface morphology using scanning electron microscope (SEM, JEOL JSM-7100F). Once optimized, these optically active nanostructures can be used to replicate with roll-to-roll process or soft lithography for various applications including displays, solar cells, and biosensors.