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Han M, Silva SM, Russo MJ, Desroches PE, Lei W, Quigley AF, Kapsa RMI, Moulton SE, Stoddart PR, Greene GW. Lubricin (PRG-4) anti-fouling coating for surface-enhanced Raman spectroscopy biosensing: towards a hierarchical separation system for analysis of biofluids. Analyst 2023; 149:63-75. [PMID: 37933547 DOI: 10.1039/d3an00910f] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023]
Abstract
Surface-enhanced Raman Spectroscopy (SERS) is a powerful optical sensing technique that amplifies the signal generated by Raman scattering by many orders of magnitude. Although the extreme sensitivity of SERS enables an extremely low limit of detection, even down to single molecule levels, it is also a primary limitation of the technique due to its tendency to equally amplify 'noise' generated by non-specifically adsorbed molecules at (or near) SERS-active interfaces. Eliminating interference noise is thus critically important to SERS biosensing and typically involves onerous extraction/purification/washing procedures and/or heavy dilution of biofluid samples. Consequently, direct analysis within biofluid samples or in vivo environments is practically impossible. In this study, an anti-fouling coating of recombinant human Lubricin (LUB) was self-assembled onto AuNP-modified glass slides via a simple drop-casting method. A series of Raman spectra were collected using rhodamine 6G (R6G) as a model analyte, which was spiked into NaCl solution or unprocessed whole blood. Likewise, we demonstrate the same sensing system for the quantitative detection of L-cysteine spiked in undiluted milk. It was demonstrated for the first time that LUB coating can mitigate the deleterious effect of fouling in a SERS sensor without compromising the detection of a target analyte, even in a highly fouling, complex medium like whole blood or milk. This feat is achieved through a molecular sieving property of LUB that separates small analytes from large fouling species directly at the sensing interface resulting in SERS spectra with low background (i.e., noise) levels and excellent analyte spectral fidelity. These findings indicate the great potential for using LUB coatings together with an analyte-selective layer to form a hierarchical separation system for SERS sensing of relevant analytes directly in complex biological media, aquaculture, food matrix or environmental samples.
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Affiliation(s)
- Mingyu Han
- Institute for Frontier Materials, Deakin University, Waurn Ponds, Victoria 3216, Australia.
- The Aikenhead Centre for Medical Discovery, St Vincent's Hospital Melbourne, Fitzroy, Victoria 3065, Australia
- Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture and Food, 671 Sneydes Road, Werribee, Victoria, 3030, Australia
| | - Saimon M Silva
- ARC Centre of Excellence for Electromaterials Science, School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
- The Aikenhead Centre for Medical Discovery, St Vincent's Hospital Melbourne, Fitzroy, Victoria 3065, Australia
- Iverson Health Innovation Research Institute, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
| | - Matthew J Russo
- Institute for Frontier Materials, Deakin University, Waurn Ponds, Victoria 3216, Australia.
| | - Pauline E Desroches
- Institute for Frontier Materials, Deakin University, Waurn Ponds, Victoria 3216, Australia.
| | - Weiwei Lei
- Institute for Frontier Materials, Deakin University, Waurn Ponds, Victoria 3216, Australia.
| | - Anita F Quigley
- The Aikenhead Centre for Medical Discovery, St Vincent's Hospital Melbourne, Fitzroy, Victoria 3065, Australia
- School of Electrical and Biomedical Engineering, RMIT University, Melbourne, Victoria 3001, Australia
| | - Robert M I Kapsa
- The Aikenhead Centre for Medical Discovery, St Vincent's Hospital Melbourne, Fitzroy, Victoria 3065, Australia
- School of Electrical and Biomedical Engineering, RMIT University, Melbourne, Victoria 3001, Australia
| | - Simon E Moulton
- ARC Centre of Excellence for Electromaterials Science, School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
- The Aikenhead Centre for Medical Discovery, St Vincent's Hospital Melbourne, Fitzroy, Victoria 3065, Australia
- Iverson Health Innovation Research Institute, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
| | - Paul R Stoddart
- School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia.
| | - George W Greene
- Institute for Frontier Materials, Deakin University, Waurn Ponds, Victoria 3216, Australia.
- ARC Centre of Excellence for Electromaterials Science, School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
- The Aikenhead Centre for Medical Discovery, St Vincent's Hospital Melbourne, Fitzroy, Victoria 3065, Australia
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2
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Lee S, Kang G, Kang J, Ko H. Exfoliation Technology for Scalable Ligand-Free Core-Semishell Metal Nanoparticle Films. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37917011 DOI: 10.1021/acsami.3c09611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
Core-shell metallic nanoparticles (NPs) are considered promising materials for their multifunctional properties. However, traditionally synthesized NPs have crucial issues that their ligands interfere with the direct interaction between NPs and neighboring materials, and it is very difficult to form a uniform film without the mixture of a template. In this article, we report an unprecedented exfoliation technology for fabricating a scalable ligand-free core-semishell metal NP film based on the evaporation system through a self-assembled monolayer-assisted surface energy control combined with a deep ultraviolet surface treatment around the core NPs. Owing to fabrication merits, the properties of the core-semishell NPs can be easily modulated depending on the shell material; the ligand-free core-shell NPs are directly attached to the surface of a material by Scotch tape, allowing interfacial interactions. Therefore, the proposed technique presents a new scientific method for studying interfacial interactions with heterogeneous materials and can be universally applied in optoelectronic devices, biopatches, photocatalysts, and so on.
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Affiliation(s)
- Seongyu Lee
- Nanophotonics Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Gumin Kang
- Nanophotonics Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - JoonHyun Kang
- Nanophotonics Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Hyungduk Ko
- Nanophotonics Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
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3
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Zhdanov G, Nyhrikova E, Meshcheryakova N, Kristavchuk O, Akhmetova A, Andreev E, Rudakova E, Gambaryan A, Yaminsky I, Aralov A, Kukushkin V, Zavyalova E. A Combination of Membrane Filtration and Raman-Active DNA Ligand Greatly Enhances Sensitivity of SERS-Based Aptasensors for Influenza A Virus. Front Chem 2022; 10:937180. [PMID: 35844641 PMCID: PMC9279936 DOI: 10.3389/fchem.2022.937180] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 05/25/2022] [Indexed: 01/20/2023] Open
Abstract
Biosensors combining the ultrahigh sensitivity of surface-enhanced Raman scattering (SERS) and the specificity of nucleic acid aptamers have recently drawn attention in the detection of respiratory viruses. The most sensitive SERS-based aptasensors allow determining as low as 104 virus particles per mL that is 100-fold lower than any antibody-based lateral flow tests but 10–100-times higher than a routine polymerase chain reaction with reversed transcription (RT-PCR). Sensitivity of RT-PCR has not been achieved in SERS-based aptasensors despite the usage of sophisticated SERS-active substrates. Here, we proposed a novel design of a SERS-based aptasensor with the limit of detection of just 103 particles per ml of the influenza A virus that approaches closely to RT-PCR sensitivity. The sensor utilizes silver nanoparticles with the simplest preparation instead of sophisticated SERS-active surfaces. The analytical signal is provided by a unique Raman-active dye that competes with the virus for the binding to the G-quadruplex core of the aptamer. The aptasensor functions even with aliquots of the biological fluids due to separation of the off-target molecules by pre-filtration through a polymeric membrane. The aptasensor detects influenza viruses in the range of 1·103–5·1010 virus particles per ml.
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Affiliation(s)
- Gleb Zhdanov
- Chemistry Department, Lomonosov Moscow State University, Moscow, Russia
| | | | | | | | - Assel Akhmetova
- Belozersky Research Institute of Physical Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | | | - Elena Rudakova
- Institute of Physiologically Active Compounds of Russian Academy of Science, Chernogolovka, Russia
| | - Alexandra Gambaryan
- Chumakov Federal Scientific Centre for Research and Development of Immune and Biological Products RAS, Moscow, Russia
| | - Igor Yaminsky
- Chemistry Department, Lomonosov Moscow State University, Moscow, Russia
- Physical Department, Lomonosov Moscow State University, Moscow, Russia
| | - Andrey Aralov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Vladimir Kukushkin
- Institute of Solid State Physics, Russian Academy of Science, Chernogolovka, Russia
| | - Elena Zavyalova
- Chemistry Department, Lomonosov Moscow State University, Moscow, Russia
- Belozersky Research Institute of Physical Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
- *Correspondence: Elena Zavyalova,
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4
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Attenuated Total Reflection at THz Wavelengths: Prospective Use of Total Internal Reflection and Polariscopy. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11167632] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Capabilities of the attenuated total reflection (ATR) at THz wavelengths for increased sub-surface depth characterisation of (bio-)materials are presented. The penetration depth of a THz evanescent wave in biological samples is dependent on the wavelength and temperature and can reach 0.1–0.5 mm depth, due to the strong refractive index change ∼0.4 of the ice-water transition; this is quite significant and important when studying biological samples. Technical challenges are discussed when using ATR for uneven, heterogeneous, high refractive index samples with the possibility of frustrated total internal reflection (a breakdown of the ATR reflection mode into transmission mode). Local field enhancements at the interface are discussed with numerical/analytical examples. Maxwell’s scaling is used to model the behaviour of absorber–scatterer inside the materials at the interface with the ATR prism for realistic complex refractive indices of bio-materials. The modality of ATR with a polarisation analysis is proposed, and its principle is illustrated, opening an invitation for its experimental validation. The sensitivity of the polarised ATR mode to the refractive index between the sample and ATR prism is numerically modelled and experimentally verified for background (air) spectra. The design principles of polarisation active optical elements and spectral filters are outlined. The results and proposed concepts are based on experimental conditions at the THz beamline of the Australian Synchrotron.
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Second Harmonic Generation from Phase-Engineered Metasurfaces of Nanoprisms. MICROMACHINES 2020; 11:mi11090848. [PMID: 32932670 PMCID: PMC7569796 DOI: 10.3390/mi11090848] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 09/01/2020] [Accepted: 09/08/2020] [Indexed: 01/07/2023]
Abstract
Metasurfaces of gold (Au) nanoparticles on a SiO2-Si substrate were fabricated for the enhancement of second harmonic generation (SHG) using electron beam lithography and lift-off. Triangular Au nanoprisms which are non-centro-symmetric and support second-order nonlinearity were examined for SHG. The thickness of the SiO2 spacer is shown to be an effective parameter to tune for maximising SHG. Electrical field enhancement at the fundamental wavelength was shown to define the SHG intensity. Numerical modeling of light enhancement was verified by experimental measurements of SHG and reflectivity spectra at the normal incidence. At the plasmonic resonance, SHG is enhanced up to ∼3.5 × 103 times for the optimised conditions.
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A sensitive and rapid bacterial antibiotic susceptibility test method by surface enhanced Raman spectroscopy. Braz J Microbiol 2020; 51:875-881. [PMID: 32347530 DOI: 10.1007/s42770-020-00282-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Accepted: 04/17/2020] [Indexed: 02/07/2023] Open
Abstract
This study aims to develop a rapid bacterial antibiotic susceptibility test (AST) method by Bacteria-aptamer@AgNPs-surface enhanced Raman spectroscopy (SERS) and further evaluate the influence of different antibiotics on the Raman intensity of bacteria. The Raman intensity of Escherichia coli O157:H7 (E. coli O157:H7) and Staphylococcus aureus (S. aureus) in the presence of different concentrations of antibiotics in 2 h was detected by Bacteria-aptamer@AgNPs-SERS in this study. Our results found that the bacteria Raman signal peak at 735 cm-1 and the minimum inhibitory concentration (MIC) value was determined in 1 h according to Raman signals. In 2 h, the bacteria Raman signal growth at sub-MIC concentrations of four different kinds of antibiotics and the bacteria colony-forming unit (CFU) have similar enhancements. SERS utilizes special functions of rough metal surfaces and offers a huge enhancement of Raman intensities with reduced fluorescence backgrounds, which makes it an ultrasensitive tool of detection. This rapid AST method and the enhancement effect should be of value in search of new antibiotic drugs.
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7
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Black Metals: Optical Absorbers. MICROMACHINES 2020; 11:mi11030256. [PMID: 32121168 PMCID: PMC7142461 DOI: 10.3390/mi11030256] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 02/26/2020] [Accepted: 02/26/2020] [Indexed: 01/11/2023]
Abstract
We demonstrate a concept and fabrication of lithography-free layered metal-SiO2 thin-film structures which have reduced reflectivity (black appearance), to as low as 0.9%, with 4.9% broadband reflectance (8.9% for soda lime) in the 500–1400 nm range. The multi-layered (four layers) thin-film metamaterial is designed so that optical impedance matching produces minimal reflectance and transmittance within the visible and infra-red (IR) spectral region for a range of incident angles. The structure has enhanced absorbance and is easily tuned for reduced minimal transmission and reflection. This approach should allow for novel anti-reflection surfaces by impedance matching to be realized.
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8
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Perera MNMN, Schmidt D, Gibbs WEK, Juodkazis S, Stoddart PR. Influence of the dielectric substrate on the effective optical constants of silver plasmonic films. APPLIED OPTICS 2019; 58:6038-6044. [PMID: 31503924 DOI: 10.1364/ao.58.006038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 07/04/2019] [Indexed: 06/10/2023]
Abstract
The effective optical properties of plasmonic thin films can be used to model the far-field response of nanostructured materials to an incident electromagnetic field. In the present work, optically thin nanostructured silver (Ag) plasmonic films were fabricated on transparent dielectric substrates of soda-lime glass, sapphire, and fused silica using oblique angle deposition. The influence of the underlying dielectric substrate on the effective optical properties of the nanostructured layer was investigated by an ellipsometric-optical model based on Mueller matrix ellipsometry. The wavelength-dependent uniaxial optical responses of the nanostructured Ag films fabricated on sapphire were modeled with three Gaussian and one Tanguy oscillator, representing key optical phenomena over the range from 300 to 1000 nm. In comparison with the same Ag films on glass, the results confirm that the effective optical properties cannot be considered in isolation from the substrate. As expected, the extinction peak associated with the localized surface plasmon resonance was redshifted by approximately 220 nm per unit of the substrate refractive index. Importantly, it was found that the direction of incidence also influences the film behavior, with a substantial redshift in the extinction peak for light directed through the dielectric compared to free-space illumination. This property can have a significant effect on the far-field performance of these films.
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9
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Rabor JB, Kawamura K, Kurawaki J, Niidome Y. Plasmon-enhanced two-photon excitation fluorescence of rhodamine 6G and an Eu-diketonate complex by a picosecond diode laser. Analyst 2019; 144:4045-4050. [PMID: 31157334 DOI: 10.1039/c9an00247b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Two-photon excited fluorescence (TPEF) of rhodamine 6G (Rh6G) and tris(dibenzoylmethane) mono(5-aminophenanthroline) europium (Eu-TDPA) was measured using a pulsed diode laser head (<45 mW, 975 nm, 90 ps pulse width, 40 MHz). Fluorophores were cast on a glass slide modified with triangular silver nanoprisms. A photon-counting photomultiplier detected the TPEF of Rh6G on a glass substrate (1361 Hz) and on the nanoprisms (6322 Hz). On the other hand, Eu-TDPA did not exhibit TPEF on a glass substrate. TPEF was only observed when the extinction of the nanoprisms on the substrates was larger than 0.1. The nanoprisms enhanced the TPEF of these two fluorophores up to the detectable level using a low-power laser diode.
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Affiliation(s)
- Janice B Rabor
- Department of Chemistry and Bioscience, Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan.
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10
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Chung T, Lee Y, Ahn MS, Lee W, Bae SI, Hwang CSH, Jeong KH. Nanoislands as plasmonic materials. NANOSCALE 2019; 11:8651-8664. [PMID: 31011743 DOI: 10.1039/c8nr10539a] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Subwavelength metal nanoislands thermally dewetted from a thin film emerge as a powerful and cost-effective photonic material, due to the formation of substantially strong nano-gap-based plasmonic hot spots and their simple large-area nanofabrication. Unlike conventional nanostructures, nanoislands dewetted from thin metal films can be formed on a large scale at the wafer level and show substrate-dependent plasmonic phenomena across a broad spectral range from ultraviolet to infrared. Substrate-selective dewetting methods for metal nanoislands enable diverse nanophotonic and optoelectronic technologies, underlining mechanical, structural, and material properties of a substrate. Emerging bioplasmonic technology using metal nanoislands also serves as a high-throughput and surface-sensitive analytical technique with wide-ranging application in rapid, real-time, and point-of-care medical diagnostics. This review introduces an assortment of dewetting fabrication methods for metal nanoislands on distinct substrates from glass to cellulose fibers and provides novel findings for metal nanoislands on a substrate by three-dimensional numerical modeling. Furthermore, the plasmonic properties of metal nanoislands and recent examples for their photonic applications, in particular, biological sensing, are technically summarized and discussed.
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Affiliation(s)
- Taerin Chung
- Department of Bio and Brain Engineering, KAIST Institute for Health Science and Technology (KIHST), Korea Advanced Institute of Science and Technology (KAIST), 291 Dahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
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11
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Takenaka M, Hashimoto Y, Iwasa T, Taketsugu T, Seniutinas G, Balčytis A, Juodkazis S, Nishijima Y. First Principles Calculations Toward Understanding SERS of 2,2'-Bipyridyl Adsorbed on Au, Ag, and Au-Ag Nanoalloy. J Comput Chem 2019; 40:925-932. [PMID: 30368857 DOI: 10.1002/jcc.25603] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 08/08/2018] [Accepted: 08/31/2018] [Indexed: 12/17/2022]
Abstract
First principles electrodyanmics and quantum chemical simulations are performed to gain insights into the underlying mechanisms of the surface enhanced Raman spectra of 22BPY adsorbed on pure Au and Ag as well as on Au-Ag alloy nanodiscs. Experimental SERS spectra from Au and Ag nanodiscs show similar peaks, whereas those from Au-Ag alloy reveal new spectral features. The physical enhancement factors due to surface nano-texture were considered by numerical FDTD simulations of light intensity distribution for the nano-textured Au, Ag, and Au-Ag alloy and compared with experimental results. For the chemical insights of the enhancement, the DFT calculations with the dispersion interaction were performed using Au20 , Ag20 , and Au10 Ag10 clusters of a pyramidal structure for SERS modeling. Binding of 22BPY to the clusters was simulated by considering possible arrangements of vertex and planar physical as well as chemical adsorption models. The DFT results indicate that 22BPY prefers a coplanar adsorption on a (111) face with trans-conformation having close energy difference to cis-conformation. Binding to pure Au cluster is stronger than to pure Ag or Au-Ag alloy clusters and adsorption onto the alloy surface can deform the surface. The computed Raman spectra are compared with experimental data and assignments for pure Au and Ag models are well matching, indicating the need of dispersion interaction to reproduce strong Raman signal at around 800 cm-1 . This work provides insight into 3D character of SERS on nanorough surfaces due to different binding energies and bond length of nanoalloys. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Masato Takenaka
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo 060-0810, Japan
| | - Yoshikazu Hashimoto
- Department of Electrical and Computer Engineering, Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Takeshi Iwasa
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo 060-0810, Japan.,Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo 060-0810, Japan.,Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Kyoto 615-8245
| | - Tetsuya Taketsugu
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo 060-0810, Japan.,Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo 060-0810, Japan.,Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Kyoto 615-8245
| | - Gediminas Seniutinas
- Centre for Micro-Photonics, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, Victoria, 3122, Australia.,Melbourne Centre for Nanofabrication (MCN), Australian National Fabrication Facility, Clayton, Victoria, 3168, Australia
| | - Armandas Balčytis
- Centre for Micro-Photonics, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, Victoria, 3122, Australia.,Melbourne Centre for Nanofabrication (MCN), Australian National Fabrication Facility, Clayton, Victoria, 3168, Australia
| | - Saulius Juodkazis
- Centre for Micro-Photonics, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, Victoria, 3122, Australia.,Melbourne Centre for Nanofabrication (MCN), Australian National Fabrication Facility, Clayton, Victoria, 3168, Australia
| | - Yoshiaki Nishijima
- Department of Electrical and Computer Engineering, Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
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12
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Zheng Y, Rosa L, Thai T, Ng SH, Juodkazis S, Bach U. Phase controlled SERS enhancement. Sci Rep 2019; 9:744. [PMID: 30679465 PMCID: PMC6346009 DOI: 10.1038/s41598-018-36491-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 10/23/2018] [Indexed: 01/23/2023] Open
Abstract
Surface-enhanced Raman spectroscopy (SERS) has attracted increasing interest for chemical and biochemical sensing. Several studies have shown that SERS intensities are significantly increased when an optical interference substrate composed of a dielectric spacer and a reflector is used as a supporting substrate. However, the origin of this additional enhancement has not been systematically studied. In this paper, high sensitivity SERS substrates composed of self-assembled core-satellite nanostructures and silica-coated silicon interference layers have been developed. Their SERS enhancement is shown to be a function of the thickness of silica spacer on a more reflective silicon substrate. Finite difference time domain modeling is presented to show that the SERS enhancement is due to a spacer contribution via a sign change of the reflection coefficients at the interfaces. The magnitude of the local-field enhancement is defined by the interference of light reflected from the silica-air and silica-silicon interfaces, which constructively added at the hot spots providing a possibility to maximize intensity in the nanogaps between the self-assembled nanoparticles by changing the thickness of silica layer. The core-satellite assemblies on a 135 nm silica-coated silicon substrate exhibit a SERS activity of approximately 13 times higher than the glass substrate.
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Affiliation(s)
- Yuanhui Zheng
- State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116, China. .,Materials Science and Engineering, Commonwealth Scientific and Industrial Research Organization, Clayton South, Victoria, 3169, Australia. .,The Melbourne Centre for Nanofabrication, 151 Wellington Road, Clayton, Victoria, 3168, Australia.
| | - Lorenzo Rosa
- Swinburne University of Technology, Centre for Micro-Photonics (H74), P.O. Box 218, Hawthorn, Victoria, 3122, Australia.,Department of Engineering "Enzo Ferrari", University of Modena and Reggio Emilia, via Vivarelli 10, I-41125, Modena, Italy
| | - Thibaut Thai
- The Melbourne Centre for Nanofabrication, 151 Wellington Road, Clayton, Victoria, 3168, Australia.,Department of Materials Engineering, Monash University, Wellington Road, Clayton, Victoria, 3800, Australia
| | - Soon Hock Ng
- The Melbourne Centre for Nanofabrication, 151 Wellington Road, Clayton, Victoria, 3168, Australia.,Department of Materials Engineering, Monash University, Wellington Road, Clayton, Victoria, 3800, Australia
| | - Saulius Juodkazis
- The Melbourne Centre for Nanofabrication, 151 Wellington Road, Clayton, Victoria, 3168, Australia. .,Swinburne University of Technology, Centre for Micro-Photonics (H74), P.O. Box 218, Hawthorn, Victoria, 3122, Australia.
| | - Udo Bach
- Materials Science and Engineering, Commonwealth Scientific and Industrial Research Organization, Clayton South, Victoria, 3169, Australia. .,The Melbourne Centre for Nanofabrication, 151 Wellington Road, Clayton, Victoria, 3168, Australia. .,Department of Materials Engineering, Monash University, Wellington Road, Clayton, Victoria, 3800, Australia.
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13
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Šubr M, Procházka M. Polarization- and Angular-Resolved Optical Response of Molecules on Anisotropic Plasmonic Nanostructures. NANOMATERIALS (BASEL, SWITZERLAND) 2018; 8:E418. [PMID: 29890758 PMCID: PMC6027211 DOI: 10.3390/nano8060418] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 05/28/2018] [Accepted: 06/07/2018] [Indexed: 11/17/2022]
Abstract
A sometimes overlooked degree of freedom in the design of many spectroscopic (mainly Raman) experiments involve the choice of experimental geometry and polarization arrangement used. Although these aspects usually play a rather minor role, their neglect may result in a misinterpretation of the experimental results. It is well known that polarization- and/or angular- resolved spectroscopic experiments allow one to classify the symmetry of the vibrations involved or the molecular orientation with respect to a smooth surface. However, very low detection limits in surface-enhancing spectroscopic techniques are often accompanied by a complete or partial loss of this detailed information. In this review, we will try to elucidate the extent to which this approach can be generalized for molecules adsorbed on plasmonic nanostructures. We will provide a detailed summary of the state-of-the-art experimental findings for a range of plasmonic platforms used in the last ~ 15 years. Possible implications on the design of plasmon-based molecular sensors for maximum signal enhancement will also be discussed.
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Affiliation(s)
- Martin Šubr
- Faculty of Mathematics and Physics, Institute of Physics, Charles University, 121 16 Prague 2, Czech Republic.
| | - Marek Procházka
- Faculty of Mathematics and Physics, Institute of Physics, Charles University, 121 16 Prague 2, Czech Republic.
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14
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Kraack JP, Sévery L, Tilley SD, Hamm P. Plasmonic Substrates Do Not Promote Vibrational Energy Transfer at Solid-Liquid Interfaces. J Phys Chem Lett 2018; 9:49-56. [PMID: 29235870 DOI: 10.1021/acs.jpclett.7b02855] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Intermolecular vibrational energy transfer in monolayers of isotopically mixed rhenium carbonyl complexes at solid-liquid interfaces is investigated with the help of ultrafast 2D Attenuated Total Reflectance Infrared (2D ATR IR) spectroscopy in dependence of plasmonic surface enhancement effects. Dielectric and plasmonic materials are used to demonstrate that plasmonic effects have no impact on the vibrational energy transfer rate in a regime of moderate IR surface enhancement (enhancement factors up to ca. 30). This result can be explained with the common image-dipole picture. The vibrational energy transfer rate thus can be used as a direct observable to determine intermolecular distances on surfaces, regardless of their plasmonic properties.
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Affiliation(s)
- Jan Philip Kraack
- Department of Chemistry, University of Zurich , Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Laurent Sévery
- Department of Chemistry, University of Zurich , Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - S David Tilley
- Department of Chemistry, University of Zurich , Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Peter Hamm
- Department of Chemistry, University of Zurich , Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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Lum W, Bruzas I, Gorunmez Z, Unser S, Beck T, Sagle L. Novel Liposome-Based Surface-Enhanced Raman Spectroscopy (SERS) Substrate. J Phys Chem Lett 2017; 8:2639-2646. [PMID: 28535675 DOI: 10.1021/acs.jpclett.7b00694] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Although great strides have been made in recent years toward making highly enhancing surface-enhanced Raman spectroscopy (SERS) substrates, the biological compatibility of such substrates remains a crucial problem. To address this issue, liposome-based SERS substrates have been constructed in which the biological probe molecule is encapsulated inside the aqueous liposome compartment, and metallic elements are assembled using the liposome as a scaffold. Therefore, the probe molecule is not in contact with the metallic surfaces. Herein we report our initial characterization of these novel nanoparticle-on-mirror substrates, both experimentally and theoretically, using finite-difference time-domain calculations. The substrates are shown to be structurally stable to laser irradiation, the liposome compartment does not rise above 45 °C, and they exhibit an analytical enhancement factor of 8 × 106 for crystal violet encapsulated in 38 liposomes sandwiched between a 40 nm planar gold mirror and 80 nm gold colloid.
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Affiliation(s)
- William Lum
- Department of Chemistry, College of Arts and Sciences, University of Cincinnati , 301 West Clifton Court, Cincinnati, Ohio 45221-0172, United States
| | - Ian Bruzas
- Department of Chemistry, College of Arts and Sciences, University of Cincinnati , 301 West Clifton Court, Cincinnati, Ohio 45221-0172, United States
| | - Zohre Gorunmez
- Department of Chemistry, College of Arts and Sciences, University of Cincinnati , 301 West Clifton Court, Cincinnati, Ohio 45221-0172, United States
| | - Sarah Unser
- Department of Chemistry, College of Arts and Sciences, University of Cincinnati , 301 West Clifton Court, Cincinnati, Ohio 45221-0172, United States
| | - Thomas Beck
- Department of Chemistry, College of Arts and Sciences, University of Cincinnati , 301 West Clifton Court, Cincinnati, Ohio 45221-0172, United States
| | - Laura Sagle
- Department of Chemistry, College of Arts and Sciences, University of Cincinnati , 301 West Clifton Court, Cincinnati, Ohio 45221-0172, United States
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Lee JC, Kim W, Park HK, Choi S. Controlling successive ionic layer absorption and reaction cycles to optimize silver nanoparticle-induced localized surface plasmon resonance effects on the paper strip. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 174:37-43. [PMID: 27865935 DOI: 10.1016/j.saa.2016.11.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 11/09/2016] [Accepted: 11/12/2016] [Indexed: 06/06/2023]
Abstract
This study investigates why a silver nanoparticle (SNP)-induced surface-enhanced Raman scattering (SERS) paper chip fabricated at low successive ionic layer absorption and reaction (SILAR) cycles leads to a high SERS enhancement factor (7×108) with an inferior nanostructure and without generating a hot spot effect. The multi-layered structure of SNPs on cellulose fibers, verified by magnified scanning electron microscopy (SEM) and analyzed by a computational simulation method, was hypothesized as the reason. The pattern of simulated local electric field distribution with respect to the number of SILAR cycles showed good agreement with the experimental Raman intensity, regardless of the wavelength of the excitation laser sources. The simulated enhancement factor at the 785-nm excitation laser source (2.8×109) was 2.5 times greater than the experimental enhancement factor (1.1×109). A 532-nm excitation laser source exhibited the highest maximum local electric field intensity (1.9×1011), particularly at the interparticle gap called a hot spot. The short wavelength led to a strong electric field intensity caused by strong electromagnetic coupling arising from the SNP-induced local surface plasmon resonance (LSPR) effects through high excitation energy. These findings suggest that our paper-based SILAR-fabricated SNP-induced LSPR model is valid for understanding SNP-induced LSPR effects.
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Affiliation(s)
- Jae-Chul Lee
- Department of Biomedical Engineering, College of Medicine, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Wansun Kim
- Department of Medical Engineering, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Hun-Kuk Park
- Department of Biomedical Engineering, College of Medicine, Kyung Hee University, Seoul 02447, Republic of Korea; Department of Medical Engineering, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Samjin Choi
- Department of Biomedical Engineering, College of Medicine, Kyung Hee University, Seoul 02447, Republic of Korea; Department of Medical Engineering, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea.
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Perera MNMN, Schmidt D, Gibbs WEK, Juodkazis S, Stoddart PR. Effective optical constants of anisotropic silver nanoparticle films with plasmonic properties. OPTICS LETTERS 2016; 41:5495-5498. [PMID: 27906222 DOI: 10.1364/ol.41.005495] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Mueller matrix ellipsometry has been used to determine the effective optical constants of island-like Ag films deposited by thermal evaporation. These films depart substantially from bulk silver with a prominent localized surface plasmon resonance. Moreover, despite the isotropic appearance, they exhibit uniaxial optical properties with the optical axis inclined by 83.4° from the substrate normal toward the direction of the incoming vapor flux. The uniaxial model supports the plasmon resonance peaks revealed by in-plane absorbance measurements of the films. The uniaxial behavior suggests that the resonances along the ordinary axes are weakly coupled between neighboring particles, whereas the extraordinary resonance is relatively strongly coupled. Therefore, the anisotropy should be considered in the practical applications of these plasmonic films.
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Maximova K, Wang X, Balčytis A, Fan L, Li J, Juodkazis S. Silk patterns made by direct femtosecond laser writing. BIOMICROFLUIDICS 2016; 10:054101. [PMID: 27679677 PMCID: PMC5010553 DOI: 10.1063/1.4962294] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/24/2016] [Indexed: 05/29/2023]
Abstract
Silk patterns in a film of amorphous water-soluble fibroin are created by tailored exposure to femtosecond-laser pulses (1030 nm/230 fs) without the use of photo-initiators. This shows that amorphous silk can be used as a negative tone photo-resist. It is also shown that water insoluble crystalline silk films can be precisely ablated from a glass substrate achieving the patterns of crystalline silk gratings on a glass substrate. Bio-compatible/degradable silk can be laser structured to achieve conformational transformations as demonstrated by infrared spectroscopy.
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Affiliation(s)
- Ksenia Maximova
- Center for Micro-Photonics, Swinburne University of Technology , John St., Hawthorn, Victoria 3122, Australia
| | - Xuewen Wang
- Center for Micro-Photonics, Swinburne University of Technology , John St., Hawthorn, Victoria 3122, Australia
| | | | - Linpeng Fan
- Australian Future Fibers Research and Innovation Centre, Institute for Frontier Materials, Deakin University , Geelong, Victoria 3220, Australia
| | - Jingliang Li
- Australian Future Fibers Research and Innovation Centre, Institute for Frontier Materials, Deakin University , Geelong, Victoria 3220, Australia
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Kang M, Zhang X, Liu L, Zhou Q, Jin M, Zhou G, Gao X, Lu X, Zhang Z, Liu J. High-density ordered Ag@Al₂O₃ nanobowl arrays in applications of surface-enhanced Raman spectroscopy. NANOTECHNOLOGY 2016; 27:165304. [PMID: 26963676 DOI: 10.1088/0957-4484/27/16/165304] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this paper, we demonstrate a high-performance surface-enhanced Raman scattering (SERS) substrate based on high-density ordered Ag@Al2O3 nanobowl arrays. By ion beam etching (IBE) the anodized aluminum oxide (AAO) and subsequent Ag coating, ordered Ag@Al2O3 nanobowl arrays were created on the Si substrate. Unlike the 'hot spots' generated between adjacent metallic nanostructures, the Ag@Al2O3 nanobowl introduced 'hot spots' on the metal boundary of its hemispherical cavity. Based on the analysis of SERS signals, the optimized SERS substrate of Ag@Al2O3 nanobowl arrays had both high sensitivity and large-area uniformity. A detection limit as low as 10(-10) M was obtained using chemisorbed p-thiocresol (p-Tc) molecules, and the SERS signal was highly reproducible with a small standard deviation. The method opens up a new way to create highly sensitive SERS sensors with high-density 'hot spots', and it could play an important role in device design and corresponding biological and food safety monitoring applications.
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Affiliation(s)
- Mengyang Kang
- Institute for Advanced Materials and Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, South China Normal University, Guangzhou 510006, People's Republic of China
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20
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Asymmetric light reflectance from metal nanoparticle arrays on dielectric surfaces. Sci Rep 2015; 5:18331. [PMID: 26679353 PMCID: PMC4683376 DOI: 10.1038/srep18331] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 11/16/2015] [Indexed: 12/02/2022] Open
Abstract
Asymmetric light reflectance associated with localized surface plasmons excited in metal nanoparticles on a quartz substrate is observed and analyzed. This phenomenon is explained by the superposition of two waves, the wave reflected by the air/quartz interface and that reflected by the metal nanoparticles, and the resulting interference effects. Far field behavior investigation suggests that zero reflection can be achieved by optimizing the density of metal nanoparticles. Near field behavior investigation suggests that the coupling efficiency of localized surface plasmon can be additionally enhanced by separating the metal NPs from substrates using a thin film with refractive index smaller than the substrate. The latter behavior is confirmed via surface-enhanced Raman spectroscopy studies using metal nanoparticles on Si/SiO2 substrates.
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Chen J, Xiao HJ, Qi T, Chen DL, Long HM, Liu SH. Rare earths exposure and male infertility: the injury mechanism study of rare earths on male mice and human sperm. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:2076-2086. [PMID: 25167826 DOI: 10.1007/s11356-014-3499-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 08/20/2014] [Indexed: 06/03/2023]
Abstract
The weight; testis/body coefficient; levels of LDH, SDH, SODH, G-6PD, and testosterone; cell cycle; and cell apoptosis of the male mice were influenced after being treated with 200 mg/[kg/day] of rare earths suspension for 3 weeks. The "Raman fingerprints" of the human sperm DNA exposed to 0.040 mg/ml CeCl3 were very different from those of the untreated; the Raman bands at 789 cm(-1) (backbone phosphodiester), PO4 backbone at 1,094 cm(-1), methylene deformation mode at 1,221 cm(-1), methylene deformation mode at 1,485 cm(-1), and amide II at 1,612 cm(-1), of which intensities and shifts were changed, might be the diagnostic biomarkers or potential therapeutic targets. The injury mechanism might be that the rare earths influence the oxidative stress and blood testosterone barrier, tangle the big biomolecule concurrently, which might cause the testicular cells and vascular system disorder and/or dysfunction, and at the same time change the physical and chemical properties of the sperm directly.
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Affiliation(s)
- Jun Chen
- Department of Infertility and Sexual Medicine, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, 510631, China
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Terekhov SN, Kachan SM, Panarin AY, Mojzes P. Surface-enhanced Raman scattering on silvered porous alumina templates: role of multipolar surface plasmon resonant modes. Phys Chem Chem Phys 2015; 17:31780-9. [DOI: 10.1039/c5cp04197j] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Nanostructured silver films with different thicknesses were prepared by vapor deposition onto the surface of the anodic aluminum oxide (AAO) template to be used as surface-enhanced Raman scattering (SERS) active substrates.
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Affiliation(s)
| | - S. M. Kachan
- Department of Information Technologies and Robotics
- Belarusian National Technical University
- 220013 Minsk
- Belarus
| | | | - P. Mojzes
- Institute of Physics
- Charles University in Prague
- CZ-121 16 Prague 2
- Czech Republic
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Toccafondi C, Thorat S, La Rocca R, Scarpellini A, Salerno M, Dante S, Das G. Multifunctional substrates of thin porous alumina for cell biosensors. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2014; 25:2411-2420. [PMID: 24573456 DOI: 10.1007/s10856-014-5178-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 02/12/2014] [Indexed: 06/03/2023]
Abstract
We have fabricated anodic porous alumina from thin films (100/500 nm) of aluminium deposited on technological substrates of silicon/glass, and investigated the feasibility of this material as a surface for the development of analytical biosensors aiming to assess the status of living cells. To this goal, porous alumina surfaces with fixed pitch and variable pore size were analyzed for various functionalities. Gold coated (about 25 nm) alumina revealed surface enhanced Raman scattering increasing with the decrease in wall thickness, with factor up to values of approximately 10(4) with respect to the flat gold surface. Bare porous alumina was employed for micro-patterning and observation via fluorescence images of dye molecules, which demonstrated the surface capability for a drug-loading device. NIH-3T3 fibroblast cells were cultured in vitro and examined after 2 days since seeding, and no significant (P > 0.05) differences in their proliferation were observed on porous and non-porous materials. The effect on cell cultures of pore size in the range of 50-130 nm--with pore pitch of about 250 nm--showed no significant differences in cell viability and similar levels in all cases as on a control substrate. Future work will address combination of all above capabilities into a single device.
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Affiliation(s)
- Chiara Toccafondi
- Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163, Genoa, Italy,
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The effect of dielectric constants on noble metal/semiconductor SERS enhancement: FDTD simulation and experiment validation of Ag/Ge and Ag/Si substrates. Sci Rep 2014; 4:4052. [PMID: 24514430 PMCID: PMC3920278 DOI: 10.1038/srep04052] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 01/20/2014] [Indexed: 12/17/2022] Open
Abstract
The finite-difference time-domain (FDTD) method was employed to simulate the electric field distribution for noble metal (Au or Ag)/semiconductor (Ge or Si) substrates. The simulation showed that noble metal/Ge had stronger SERS enhancement than noble metal/Si, which was mainly attributed to the different dielectric constants of semiconductors. In order to verify the simulation, Ag nanoparticles with the diameter of ca. 40 nm were grown on Ge or Si wafer (Ag/Ge or Ag/Si) and employed as surface-enhanced Raman scattering substrates to detect analytes in solution. The experiment demonstrated that both the two substrates exhibited excellent performance in the low concentration detection of Rhodamine 6G. Besides, the enhancement factor (1.3 × 109) and relative standard deviation values (less than 11%) of Ag/Ge substrate were both better than those of Ag/Si (2.9 × 107 and less than 15%, respectively), which was consistent with the FDTD simulation. Moreover, Ag nanoparticles were grown in-situ on Ge substrate, which kept the nanoparticles from aggregation in the detection. To data, Ag/Ge substrates showed the best performance for their sensitivity and uniformity among the noble metal/semiconductor ones.
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Hartley JS, Juodkazis S, Stoddart PR. Optical fibers for miniaturized surface-enhanced Raman-scattering probes. APPLIED OPTICS 2013; 52:8388-93. [PMID: 24513843 DOI: 10.1364/ao.52.008388] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 11/07/2013] [Indexed: 05/22/2023]
Abstract
A range of optical fibers with surface-enhanced Raman scattering (SERS) functionalized tips have been evaluated for use as micro-scale sensing devices. In order to optimize the sensitivity of the optical fiber probe, the relationship between SERS intensity and different fiber parameters was investigated. It was found that the numerical aperture, core size, mode structure, and core material have a major effect on the probe performance, as does the numerical aperture of the microscope objective. The results suggest that an ideal fiber for SERS sensing should be single mode at the excitation wavelength and have low-background core material.
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