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Khoury CG, Vo-Dinh T. Plasmonic "Nanowave" Substrates for SERS: Fabrication and Numerical Analysis. J Phys Chem C Nanomater Interfaces 2012; 116:7534-7545. [PMID: 24839506 PMCID: PMC4022311 DOI: 10.1021/jp2120669] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The "Nanowave" substrate, comprising a close-packed array of nanospheres onto which a thin metal shell of silver or gold is deposited, was first fabricated in our laboratory in 1984 and used as a surface-enhanced Raman scattering (SERS)-active substrate for the sensitive and reproducible detection of analytes. More than twenty-five years after the first experimental demonstration of the effectiveness of this substrate, numerical simulations are sufficiently powerful and versatile to mimic this geometry in three dimensional space and confirm the experimentally measured plasmonic behavior at the substrate's surface. The study confirms that an in-plane polarized incident plane wave generates strong enhancements in the interstitial spaces between individual metal-coated nanospheres, thus producing closely packed arrays of hot spots underlining the strong SERS effect of the Nanowave substrate structures. The surface-averaged SERS enhancement exhibited by the Nanowaves was evaluated and compared for different metal thicknesses. The effect of structural confinement on the plasmonic behavior of the Nanowave structure was investigated by varying the structural confinement of the substrate in the plane parallel to the incident excitation. The Nanowave is an inexpensive, reproducible and effective plasmonics-active substrate that has the potential to be used for SERS studies requiring high detection sensitivity.
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Affiliation(s)
- Christopher G Khoury
- Fitzpatrick Institute of Photonics, Duke University, Durham, Department of BME, Duke University, Durham, and Department of Chemistry, Duke University, Durham, NC 27708
| | - Tuan Vo-Dinh
- Fitzpatrick Institute of Photonics, Duke University, Durham, Department of BME, Duke University, Durham, and Department of Chemistry, Duke University, Durham, NC 27708
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202
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Hao Q, Wang B, Bossard JA, Kiraly B, Zeng Y, Chiang IK, Jensen L, Werner DH, Huang TJ. Surface-Enhanced Raman Scattering Study on Graphene-Coated Metallic Nanostructure Substrates. J Phys Chem C Nanomater Interfaces 2012; 116:7249-7254. [PMID: 24772200 PMCID: PMC3998773 DOI: 10.1021/jp209821g] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Graphene, which has a linear electronic band structure, is widely considered as a semimetal. In the present study, we combine graphene with conventional metallic surface-enhanced Raman scattering (SERS) substrates to achieve higher sensitivity of SERS detection. We synthesize high-quality, single-layer graphene sheets by chemical vapor deposition (CVD) and transfer them from copper foils to gold nanostructures, i.e., nanoparticle or nanohole arrays. SERS measurements are carried out on methylene blue (MB) molecules. The combined graphene nanostructure substrates show about threefold or ninefold enhancement in the Raman signal of MB, compared with the bare nanohole or nanoparticle substrates, respectively. The difference in the enhancement factors is explained by the different morphologies of graphene on the two substrates with the aid of numerical simulations. Our study indicates that applying graphene to SERS substrates can be an effective way to improve the sensitivity of conventional metallic SERS substrates.
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Affiliation(s)
- Qingzhen Hao
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802
- Department of Physics, The Pennsylvania State University, University Park, PA 16802
| | - Bei Wang
- Department of Physics, The Pennsylvania State University, University Park, PA 16802
| | - Jeremy A. Bossard
- Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802
| | - Brian Kiraly
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802
| | - Yong Zeng
- Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802
| | - I-Kao Chiang
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802
| | - Lasse Jensen
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
| | - Douglas H. Werner
- Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802
| | - Tony Jun Huang
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802
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203
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Huang C, Jiang J, Muangphat C, Sun X, Hao Y. Trapping Iron Oxide into Hollow Gold Nanoparticles. Nanoscale Res Lett 2011; 6:43. [PMID: 27502665 PMCID: PMC3211847 DOI: 10.1007/s11671-010-9792-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Accepted: 09/09/2010] [Indexed: 06/06/2023]
Abstract
Synthesis of the core/shell-structured Fe3O4/Au nanoparticles by trapping Fe3O4 inside hollow Au nanoparticles is described. The produced composite nanoparticles are strongly magnetic with their surface plasmon resonance peaks in the near infrared region (wavelength from 700 to 800 nm), combining desirable magnetic and plasmonic properties into one nanoparticle. They are particularly suitable for in vivo diagnostic and therapeutic applications. The intact Au surface provides convenient anchorage sites for attachment of targeting molecules, and the particles can be activated by both near infrared lights and magnetic fields. As more and more hollow nanoparticles become available, this synthetic method would find general applications in the fabrication of core-shell multifunctional nanostructures.
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Affiliation(s)
- Chienwen Huang
- Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, TX, 76019, USA
| | - Jiechao Jiang
- Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, TX, 76019, USA
| | - Chivarat Muangphat
- Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, TX, 76019, USA
| | - Xiankai Sun
- Department of Radiology and Advanced Imaging Research Center, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, 75390, USA
| | - Yaowu Hao
- Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, TX, 76019, USA.
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204
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Vo-Dinh T, Dhawan A, Norton SJ, Khoury CG, Wang HN, Misra V, Gerhold MD. Plasmonic Nanoparticles and Nanowires: Design, Fabrication and Application in Sensing. J Phys Chem C Nanomater Interfaces 2010; 114:7480-7488. [PMID: 24839505 PMCID: PMC4022305 DOI: 10.1021/jp911355q] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This study involves two aspects of our investigations of plasmonics-active systems: (i) theoretical and simulation studies and (ii) experimental fabrication of plasmonics-active nanostructures. Two types of nanostructures are selected as the model systems for their unique plasmonics properties: (1) nanoparticles and (2) nanowires on substrate. Special focus is devoted to regions where the electromagnetic field is strongly concentrated by the metallic nanostructures or between nanostructures. The theoretical investigations deal with dimers of nanoparticles and nanoshells using a semi-analytical method based on a multipole expansion (ME) and the finite-element method (FEM) in order to determine the electromagnetic enhancement, especially at the interface areas of two adjacent nanoparticles. The experimental study involves the design of plasmonics-active nanowire arrays on substrates that can provide efficient electromagnetic enhancement in regions around and between the nanostructures. Fabrication of these nanowire structures over large chip-scale areas (from a few millimeters to a few centimeters) as well as FDTD simulations to estimate the EM fields between the nanowires are described. The application of these nanowire chips using surface-enhanced Raman scattering (SERS) for detection of chemicals and labeled DNA molecules is described to illustrate the potential of the plasmonics chips for sensing.
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Affiliation(s)
- Tuan Vo-Dinh
- Fitzpatrick Institute for Photonics, Departments of Biomedical Engineering and Chemistry, Duke University, Durham, NC 27708, USA
| | - Anuj Dhawan
- Fitzpatrick Institute for Photonics, Departments of Biomedical Engineering and Chemistry, Duke University, Durham, NC 27708, USA
| | - Stephen J. Norton
- Fitzpatrick Institute for Photonics, Departments of Biomedical Engineering and Chemistry, Duke University, Durham, NC 27708, USA
| | - Christopher G. Khoury
- Fitzpatrick Institute for Photonics, Departments of Biomedical Engineering and Chemistry, Duke University, Durham, NC 27708, USA
| | - Hsin-Neng Wang
- Fitzpatrick Institute for Photonics, Departments of Biomedical Engineering and Chemistry, Duke University, Durham, NC 27708, USA
| | - Veena Misra
- Department of Electrical and Computer Engineering, NC State University, Raleigh, NC 27606, USA
| | - Michael D. Gerhold
- Electronics Division, US Army Research Office, Research Triangle Park, Durham, NC 27703, USA
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205
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Zhou X, Zhang N, Tan C. Profile prediction and fabrication of wet-etched gold nanostructures for localized surface plasmon resonance. Nanoscale Res Lett 2009; 5:344-352. [PMID: 20672106 PMCID: PMC2894108 DOI: 10.1007/s11671-009-9486-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Accepted: 10/29/2009] [Indexed: 05/29/2023]
Abstract
Dispersed nanosphere lithography can be employed to fabricate gold nanostructures for localized surface plasmon resonance, in which the gold film evaporated on the nanospheres is anisotropically dry etched to obtain gold nanostructures. This paper reports that by wet etching of the gold film, various kinds of gold nanostructures can be fabricated in a cost-effective way. The shape of the nanostructures is predicted by profile simulation, and the localized surface plasmon resonance spectrum is observed to be shifting its extinction peak with the etching time.(See supplementary material 1).
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Affiliation(s)
- Xiaodong Zhou
- Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 3, Research Link, Singapore, 117602, Singapore.
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206
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Khoury CG, Vo-Dinh T. Gold Nanostars For Surface-Enhanced Raman Scattering: Synthesis, Characterization and Optimization. J Phys Chem C Nanomater Interfaces 2008; 2008:18849-18859. [PMID: 23977403 PMCID: PMC3748989 DOI: 10.1021/jp8054747] [Citation(s) in RCA: 401] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The controlled synthesis of high-yield gold nanostars of varying sizes, their characterization and use in surface-enhanced Raman scattering (SERS) measurements are reported for the first time. Gold nanostars ranging from 45 to 116-nm in size were synthesized in high-yield, physically modeled and optically characterized using transmission and scanning electron microscopy and UV-Visible absorption spectroscopy. The nanostar characterization involved both studying morphology evolution over time and size as a function of nucleation. The nanostars properties as substrates for SERS were investigated and compared with respect to size. As the overall star size increases, so does the core size, the number of branches and branch aspect ratio; the number of branch tips per star surface area decreases with increasing size. The stars become more inhomogeneous in shape, although their yield is high and overall size remains homogeneous. Variations in star size are also accompanied by shifts of the long plasmon band in the NIR region, which hints towards tuning capabilities that may be exploited in specific SERS applications. The measured SERS enhancement factors suggest an interesting correlation between nanostar size and SERS efficiencies, and were relatively consistent across different star samples, with the enhancement factor estimated as 5×103 averaged over the 52-nm nanostars for 633-nm excitation.
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Affiliation(s)
- Christopher G. Khoury
- Fitzpatrick Institute for Photonics, Duke University, Durham, NC 27708, USA
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Tuan Vo-Dinh
- Fitzpatrick Institute for Photonics, Duke University, Durham, NC 27708, USA
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
- Department of Chemistry, Duke University, Durham, NC 27708, USA
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