1.      M13 Bacteriophage/Silver Nanowire Surface-Enhanced Raman Scattering Sensor for Sensitive and Selective Pesticide Detection

Publication date: 2018

Eun Hye Koh, ChaeWon Mun, ChunTae Kim, Sung-Gyu Park, Eun Jung Choi, Sun Ho Kim, Jaejeung Dang, Jaebum Choo, Jin-Woo Oh, Dong-Ho Kim, and Ho Sang Jung

Abstract:

A surface-enhanced Raman scattering (SERS) sensor comprising silver nanowires (AgNWs) and genetically engineered M13 bacteriophages expressing a tryptophan?histidine?tryptophan (WHW) peptide sequence (BPWHW) was fabricated by simple mixing of BPWHW and AgNW solutions, followed by vacuum filtration onto a glass-fiber filter paper (GFFP) membrane. The AgNWs stacked on the GFFP formed a high density of SERS-active hot spots at the points of nanowire intersections, and the surface-coated BPWHW functioned as a bioreceptor for selective pesticide detection. The BPWHW[1]functionalized AgNW (BPWHW/AgNW) sensor was characterized by scanning electron microscopy, confocal scanning fluorescence microscopy, atomic force microscopy, and Fourier transform infrared spectroscopy. The Raman signal enhancement and the selective pesticide SERS detection properties of the BPWHW/AgNW sensor were investigated in the presence of control substrates such as wild-type M13 bacteriophage-decorated AgNWs (BPWT/AgNW) and undecorated AgNWs (AgNW). The BPWHW/AgNW sensor exhibited a significantly higher capture capability for pesticides, especially paraquat (PQ), than the control SERS substrates, and it also showed a relatively higher selectivity for PQ than for other bipyridylium pesticides such as diquat and difenzoquat. Furthermore, as a field application test, PQ was detected on the surface of PQ-pretreated apple peels, and the results demonstrated the feasibility of using a paper-based SERS substrate for on-site residual pesticide detection. The developed M13 bacteriophage-functionalized AgNW SERS sensor might be applicable for the detection of various pesticides and chemicals through modification of the M13 bacteriophage surface peptide sequence.

涉及技術：NS200 Series Raman

關鍵詞：M13 Bacteriophage, silver nanowires, surface-enhanced Raman scattering, chemical sensor, pesticide detection

2.      Hydrophobic hBN-coated surface-enhanced Raman scattering sponge sensor for simultaneous separation and detection of organic pollutants?

Publication date: August 2019

Ho Sang Jung,a Eun Hye Koh, ChaeWon Mun, Jeongho Min,  Woosuk Sohng, Hoeil Chung,  Jun-Yeong Yang,ad Seunghun Lee, Hyo Jung Kim, Sung-Gyu Park,  Min-Young Lee and Dong-Ho Kim

Abstract:

A sponge-based surface-enhanced Raman scattering (SERS) sensor composed of silver nanowires (AgNWs) coated with hydrophobic hexagonal boron nitride (hBN) was prepared for the simultaneous separation and detection of organic pollutants. AgNWs adhered on a melamine-sponge surface formed a high density of hotspots for Raman signal enhancement, and hydrophobic hBN coated on AgNWs functioned as an absorbent for the separation of organic pollutants from water via hydrophobic and p–p interactions. Due to the advantages of Raman spectroscopy, which provides an intrinsic molecular Raman signal, typical organic pollutants such as benzene, toluene, ethylbenzene, and xylene (BTEX) were identified by a portable Raman spectrometer with a label-free method after separation through the developed sensor. Further, binary and ternary mixtures of BTEX were also recognized by comparing the Raman spectrum of each component in the mixtures and easily classified by principal component analysis (PCA). Finally, absorbent capacity, reusability tests, and application to environmental water using the developed hBN/AgNWs/sponge samples showed the excellent organic pollutant separation properties as a hydrophobic sponge and the cost effective utilization of the developed sensor for molecular detection. The developed hBN/AgNWs/sponge sensor is expected to be applicable for various on-site and label-free separations and identifications of organic substances, such as environmental and biomedical monitoring

涉及技術：NS200 Series Raman

關鍵詞：SERS, hydrophobic hexagonal boron nitride

3.      A facile low-cost paper-based SERS substrate for label-free molecular detection

Publication date: April 2019

Vo Thi Nhat Linha , Jungil Moonc, ChaeWon Muna , Vasanthan Devarajd , Jin-Woo Ohd , Sung-Gyu Parka , Dong-Ho Kima , Jaebum Chooe , Yong-Ill Leeb, Ho Sang Junga,

Abstract:

We introduce a facile and low-cost method for fabricating gold nanostructures on cellulose filter paper (CFP) to prepare a paper-based surface-enhanced Raman scattering (SERS) sensor for label-free molecular detection. Polymerized dopamine (PD) was used as an adhesive layer on the CFP and simultaneously functioned as a reducing agent for gold nanoparticle (AuNP) nucleation. The size of the AuNPs was dependent on the pH of the gold precursor solution, and nanoparticles with an average size of 102 nm were formed on the PD-coated CFP at a pH 3, exhibiting high SERS activity. Finite-difference time-domain (FDTD) simulations of the electromagnetic field enhancement of AuNPs with different sizes and interparticle distances were performed to identify the origin of the SERS effect. The developed paper-based SERS substrate showed uniform and excellent molecular sensitivity with a limit of detection (LOD) of 10?7 M for methylene blue, as measured by a portable Raman spectrometer. Furthermore, as a field application test, surfaces of apples were pretreated with diquat (DQ) and paraquat (PQ) pesticides, which were then detected down to a concentration of 1 ppm after simple attachment of the sensor on the apple peels and performing a SERS measurement. The developed paper-based SERS sensor is expected to be applicable as a label-free sensor for a variety of chemical and biological molecules.

涉及技術：NS200 Series Raman

關鍵詞：SERS, PD, AuNP, FDTD

4.      A cyclodextrin-decorated plasmonic gold nanosatellite substrate for selective detection of bipyridylium pesticides

Publication date: August, 2020

Eun Hye Koh, Ji-Young Moon,c Sung-Youn Kim, Won-Chul Lee, Sung-Gyu Park, Dong-Ho Kim and Ho Sang Jung

Abstract:

A cyclodextrin-decorated gold nanosatellite (AuNSL) substrate was developed as a surface-enhanced Raman scattering sensor for the selective sensing of bipyridylium pesticides such as paraquat (PQ), diquat (DQ), and difenzoquat (DIF). The AuNSL structure was fabricated via vacuum deposition of gold nanoparticles (AuNPs) on a gold nanopillar substrate, and a large density of hot-spots was formed for Raman signal enhancement. Thiolated β-cyclodextrin (SH-CD) was surface-modified on the AuNSL as a chemical receptor. The detection limit of PQ, DQ, and DIF on the SH-CD-coated AuNSL (CD-AuNSL) was 0.05 ppm for each, and showed linear correlation in a concentration range of 10 ppm–0.05 ppm. Then, selective bipyridylium pesticide detection was performed by comparing the Raman intensity of each pes[1]ticide with and without the washing step. After the washing step, 90% of the PQ, DQ, and DIF Raman signals were maintained on the CD-AuNSL substrate with a uniform selectivity in a mapping area of 200 μm × 200 μm. Furthermore, selective pesticide detection was performed using a ground-apple solution without pretreatment. Raman signals were clearly observed after the washing step and they showed a limit of detection down to a concentration of 0.05 ppm for each pesticide. Principal component analysis (PCA) of the binary and ternary mixtures of PQ, DQ, and DIF showed that each component could be easily identified via the typical Raman fingerprint analysis. The developed CD-AuNSL is expected to be applied for various chemical sensors, especially for pyridine-containing toxic substances in the environ[1]ment and metabolite biomarkers in biofluids

涉及技術：NS200 Series Raman

關鍵詞：AuNSI , PQ, DQ, DIF

5.      Bioinspired plasmonic nanoflower-decorated microneedle for label-free intradermal sensing

Publication date: December ,2020

Vo Thi Nhat Linh , Sang-Gu Yim , ChaeWon Mun, Jun-Yeong Yang, Seunghun Lee , Yeon Woo Yoo , Dong Kyung Sung , Yong-Ill Lee , Dong-Ho Kim , Sung-Gyu Park , Seung Yun Yang , Ho Sang Jung

Abstract:

A bioinspired nanoflower structure was fabricated on microneedle (MN) to utilize as a surface-enhanced Raman scattering (SERS) sensor for intradermal sensing applications. On the surface of poly (lactic-co-glycolic acid) (PLGA) MN, polydopamine (PD) was coated as an interlayer, and the hydroxyapatite (HA) which is a flower-like structured bone mineral was crystalized via a bio-mineralization in simulated body fluid (SBF). Au was deposited on the HA-coated microneedle (HA-MN) to generate SERS effect. Scanning electron microscopy (SEM) images showed the nanoflower structures of Au-coated HA-MN (Au-nanoflower on microneedle; NFMN) and dense Au nanoislands (AuILs) formed on each lath-like petal surface. After SERS characterization of the NFMN-SERS sensor, electromagnetic field distribution was investigated by finite-difference time-domain (FDTD) simulation to identify origin of the SERS effect. On the NFMN-SERS sensor, methylene blue (MB) was detected down to a concentration of 50 nM with uniform tip-to-tip signal intensity. Furthermore, the feasibility of the NFMN-SERS sensor for intradermal sensing was investigated using a skin phantom model. The MB molecule contained in the dermis region was detected down to 1 nM after simple insertion and withdrawal. The developed NFMN-SERS sensor is expected to be applied for various intradermal sensing, especially for chemical biomarkers in interstitial fluids of skin.

涉及技術：NS200 Series Raman

關鍵詞：MN, SERS, PLGA