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Hardy M, Goldberg Oppenheimer P. 'When is a hotspot a good nanospot' - review of analytical and hotspot-dominated surface enhanced Raman spectroscopy nanoplatforms. NANOSCALE 2024; 16:3293-3323. [PMID: 38273798 PMCID: PMC10868661 DOI: 10.1039/d3nr05332f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Accepted: 01/13/2024] [Indexed: 01/27/2024]
Abstract
Substrate development in surface-enhanced Raman spectroscopy (SERS) continues to attract research interest. In order to determine performance metrics, researchers in foundational SERS studies use a variety of experimental means to characterize the nature of substrates. However, often this process would appear to be performed indiscriminately without consideration for the physical scale of the enhancement phenomena. Herein, we differentiate between SERS substrates whose primary enhancing structures are on the hundreds of nanometer scale (analytical SERS nanosubstrates) and those whose main mechanism derives from nanometric-sized gaps (hot-spot dominated SERS substrates), assessing the utility of various characterization methods for each substrate class. In this context, characterization approaches in white-light spectroscopy, electron beam methods, and scanning probe spectroscopies are reviewed. Tip-enhanced Raman spectroscopy, wavelength-scanned SERS studies, and the impact of surface hydrophobicity are also discussed. Conclusions are thus drawn on the applicability of each characterization technique regarding amenability for SERS experiments that have features at different length scales. For instance, while white light spectroscopy can provide an indication of the plasmon resonances associated with 10 s-100 s nm-scale structures, it may not reveal information about finer surface texturing on the true nm-scale, critical for SERS' sensitivity, and in need of investigation via scanning probe techniques.
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Affiliation(s)
- Mike Hardy
- School of Chemical Engineering, College of Engineering and Physical Sciences, University of Birmingham, B15 2TT, UK.
- Centre for Quantum Materials and Technologies, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, UK.
| | - Pola Goldberg Oppenheimer
- School of Chemical Engineering, College of Engineering and Physical Sciences, University of Birmingham, B15 2TT, UK.
- Healthcare Technologies Institute, Institute of Translational Medicine, Birmingham B15 2TH, UK
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2
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Li C, Zhang Y, Ye Z, Bell SEJ, Xu Y. Combining surface-accessible Ag and Au colloidal nanomaterials with SERS for in situ analysis of molecule-metal interactions in complex solution environments. Nat Protoc 2023; 18:2717-2744. [PMID: 37495750 DOI: 10.1038/s41596-023-00851-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 05/03/2023] [Indexed: 07/28/2023]
Abstract
The interactions between molecules and noble metal nanosurfaces play a central role in many areas of nanotechnology. The surface chemistry of noble metal surfaces under ideal, clean conditions has been extensively studied; however, clean conditions are seldom met in real-world applications. We developed a sensitive and robust characterization technique for probing the surface chemistry of nanomaterials in the complex environments that are directly relevant to their applications. Surface-enhanced Raman spectroscopy (SERS) can be used to probe the interaction of plasmonic nanoparticles with light to enhance the Raman signals of molecules near the surface of nanoparticles. Here, we explain how to couple SERS with surface-accessible plasmonic-enhancing substrates, which are capped with weakly adsorbing capping ligands such as citrate and chloride ions, to allow molecule-metal interactions to be probed in situ and in real time, thus providing information on the surface orientation and the formation and breaking of chemical bonds. The procedure covers the synthesis and characterization of surface-accessible colloids, the preliminary SERS screening with agglomerated colloids, the synthesis and characterization of interfacial nanoparticle assemblies, termed metal liquid-like films, and the in situ biphasic SERS analysis with metal liquid-like films. The applications of the approach are illustrated using two examples: the probing of π-metal interactions and that of target/ligand-particle interactions on hollow bimetallic nanostars. This protocol, from the initial synthesis of the surface-accessible plasmonic nanoparticles to the final in situ biphasic SERS analysis, requires ~14 h and is ideally suited to users with basic knowledge in performing Raman spectroscopy and wet synthesis of metal nanoparticles.
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Affiliation(s)
- Chunchun Li
- School of Chemistry and Chemical Engineering, Queen's University Belfast, Belfast, UK
- Institute of Photochemistry and Photofunctional Materials, University of Shanghai for Science and Technology, Shanghai, China
| | - Yingrui Zhang
- School of Chemistry and Chemical Engineering, Queen's University Belfast, Belfast, UK
| | - Ziwei Ye
- Key Laboratory for Advanced Materials, Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai, China
| | - Steven E J Bell
- School of Chemistry and Chemical Engineering, Queen's University Belfast, Belfast, UK.
| | - Yikai Xu
- School of Chemistry and Chemical Engineering, Queen's University Belfast, Belfast, UK.
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai, China.
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3
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Kang Y, Kim HJ, Lee SH, Noh H. Paper-Based Substrate for a Surface-Enhanced Raman Spectroscopy Biosensing Platform-A Silver/Chitosan Nanocomposite Approach. BIOSENSORS 2022; 12:266. [PMID: 35624567 PMCID: PMC9138243 DOI: 10.3390/bios12050266] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/15/2022] [Accepted: 04/20/2022] [Indexed: 06/15/2023]
Abstract
Paper is a popular platform material in all areas of sensor research due to its porosity, large surface area, and biodegradability, to name but a few. Many paper-based nanocomposites have been reported in the last decade as novel substrates for surface-enhanced Raman spectroscopy (SERS). However, there are still limiting factors, like the low density of hot spots or loss of wettability. Herein, we designed a process to fabricate a silver-chitosan nanocomposite layer on paper celluloses by a layer-by-layer method and pH-triggered chitosan assembly. Under microscopic observation, the resulting material showed a nanoporous structure, and silver nanoparticles were anchored evenly over the nanocomposite layer. In SERS measurement, the detection limit of 4-aminothiophenol was 5.13 ppb. Furthermore, its mechanical property and a strategy toward further biosensing approaches were investigated.
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Affiliation(s)
- Yuri Kang
- Department of Optometry, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811, Korea; (Y.K.); (H.J.K.)
| | - Hyeok Jung Kim
- Department of Optometry, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811, Korea; (Y.K.); (H.J.K.)
| | - Sung Hoon Lee
- Corning Technology Center Korea, Corning Precision Materials Co., Ltd., 212 Tangjeong-ro, Asan 31454, Korea
| | - Hyeran Noh
- Department of Optometry, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811, Korea; (Y.K.); (H.J.K.)
- Convergence Institute of Biomedical Engineering and Biomaterials, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811, Korea
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4
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Siebe HS, Chen Q, Li X, Xu Y, Browne WR, Bell SEJ. Filter paper based SERS substrate for the direct detection of analytes in complex matrices. Analyst 2021; 146:1281-1288. [PMID: 33426548 DOI: 10.1039/d0an02103b] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Surface-enhanced Raman spectroscopy (SERS) is an emerging analytical technique for chemical analysis, which is favourable due to its combination of short measurement time, high sensitivity and molecular specificity. However, the application of SERS is still limited, largely because in real samples the analyte is often present in a complex matrix that contains micro/macro particles that block the probe laser, as well as molecular contaminants that compete for the enhancing surface. Here, we show a simple and scalable spray-deposition technique to fabricate SERS-active paper substrates which combine sample filtration and enhancement in a single material. Unlike previous spray-deposition methods, in which simple colloidal nanoparticles were sprayed onto solid surfaces, here the colloidal nanoparticles are mixed with hydroxyethyl cellulose (HEC) polymer before application. This leads to significantly improved uniformity in the distribution of enhancing particles as the film dries on the substrate surface. Importantly, the polymer matrix also protects the enhancing particles from air-oxidation during storage but releases them to provide SERS enhancement when the film is rehydrated. These SERS-paper substrates are highly active and a model analyte, crystal violet, was detected down to 4 ng in 10 μL of sample with less than 20% point-by-point signal deviation. The filter paper and HEC effectively filter out both interfering micro/macro particles and molecular (protein) contaminants, allowing the SERS-paper substrates to be used for SERS detection of thiram in mud and melamine in the presence of protein down to nanogram levels without sample pre-treatment or purification.
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Affiliation(s)
- Harmke S Siebe
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
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Li YT, Yang YY, Sun YX, Cao Y, Huang YS, Han S. Electrochemical fabrication of reduced MoS2-based portable molecular imprinting nanoprobe for selective SERS determination of theophylline. Mikrochim Acta 2020; 187:203. [DOI: 10.1007/s00604-020-4201-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 02/28/2020] [Indexed: 01/20/2023]
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Anderson WJ, Nowinska K, Hutter T, Mahajan S, Fischlechner M. Tuning plasmons layer-by-layer for quantitative colloidal sensing with surface-enhanced Raman spectroscopy. NANOSCALE 2018; 10:7138-7146. [PMID: 29616248 DOI: 10.1039/c7nr06656b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Surface-enhanced Raman spectroscopy (SERS) is well known for its high sensitivity that emerges due to the plasmonic enhancement of electric fields typically on gold and silver nanostructures. However, difficulties associated with the preparation of nanostructured substrates with uniform and reproducible features limit reliability and quantitation using SERS measurements. In this work we use layer-by-layer (LbL) self-assembly to incorporate multiple functional building blocks of collaborative assemblies of nanoparticles on colloidal spheres to fabricate SERS sensors. Gold nanoparticles (AuNPs) are packaged in discrete layers, effectively 'freezing nano-gaps', on spherical colloidal cores to achieve multifunctionality and reproducible sensing. Coupling between layers tunes the plasmon resonance for optimum SERS signal generation to achieve a 10 nM limit of detection. Significantly, using the layer-by-layer construction, SERS-active AuNP layers are spaced out and thus optically isolated. This uniquely allows the creation of an internal standard within each colloidal sensor to enable highly reproducible self-calibrated sensing. By using 4-mercaptobenzoic acid (4-MBA) as the internal standard adenine concentrations are quantified to an accuracy of 92.6-99.5%. Our versatile approach paves the way for rationally designed yet quantitative colloidal SERS sensors and their use in a variety of sensing applications.
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Affiliation(s)
- William J Anderson
- Department of Chemistry and Institute for Life Sciences, University of Southampton, Highfield, SO17 1BJ, UK.
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7
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Canrinus T, Lee WWY, Feringa BL, Bell SEJ, Browne WR. Supramolecular Low-Molecular-Weight Hydrogelator Stabilization of SERS-Active Aggregated Nanoparticles for Solution and Gas Sensing. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:8805-8812. [PMID: 28669185 PMCID: PMC5588087 DOI: 10.1021/acs.langmuir.7b01445] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 06/23/2017] [Indexed: 06/07/2023]
Abstract
The potential of surface-enhanced Raman scattering (SERS) spectroscopy in both laboratory and field analyses depends on the reliable formation of so-called SERS hot spots, such as those formed during gold or silver nanoparticle aggregation. Unfortunately such aggregates are not stable in solution because they typically grow until they precipitate. Here we describe the use of low-molecular-weight hydrogels formed through pH-triggered self-assembly that occurs at a rate that well matches the rates of aggregation of Au or Ag colloids, allowing them to be trapped at the SERS-active point in the aggregation process. We show that the colloid-containing gels give SERS signals similar to the parent colloid but are stable over several months. Moreover, lyophilized gels can be stored as dry powders for subsequent use in the analyses of gases and dissolved analytes by contact with either solutions or vapors. The present system shows how the combination of pH-switchable low-molecular-weight gelators and pH-induced colloid aggregation can be combined to make a highly stable, low-cost SERS platform for the detection of volatile organic compounds and the microvolume analysis of solutions.
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Affiliation(s)
- Tjalling
R. Canrinus
- Molecular
Inorganic Chemistry, Stratingh Institute for Chemistry and Synthetic Organic
Chemistry, Stratingh Institute for Chemistry, Faculty
of Mathematics and Natural Sciences, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Wendy W. Y. Lee
- School
of Chemistry and Chemical Engineering, Queen’s
University Belfast, David
Keir Building, Stranmillis Road, Belfast, BT9 5AG Northern Ireland
| | - Ben L. Feringa
- Molecular
Inorganic Chemistry, Stratingh Institute for Chemistry and Synthetic Organic
Chemistry, Stratingh Institute for Chemistry, Faculty
of Mathematics and Natural Sciences, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Steven E. J. Bell
- School
of Chemistry and Chemical Engineering, Queen’s
University Belfast, David
Keir Building, Stranmillis Road, Belfast, BT9 5AG Northern Ireland
| | - Wesley R. Browne
- Molecular
Inorganic Chemistry, Stratingh Institute for Chemistry and Synthetic Organic
Chemistry, Stratingh Institute for Chemistry, Faculty
of Mathematics and Natural Sciences, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
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8
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Dick S, Konrad MP, Lee WWY, McCabe H, McCracken JN, Rahman TMD, Stewart A, Xu Y, Bell SEJ. Surface-Enhanced Raman Spectroscopy as a Probe of the Surface Chemistry of Nanostructured Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:5705-5711. [PMID: 26822589 DOI: 10.1002/adma.201505355] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 12/11/2015] [Indexed: 06/05/2023]
Abstract
Surface-enhanced Raman spectroscopy (SERS) is now widely used as a rapid and inexpensive tool for chemical/biochemical analysis. The method can give enormous increases in the intensities of the Raman signals of low-concentration molecular targets if they are adsorbed on suitable enhancing substrates, which are typically composed of nanostructured Ag or Au. However, the features of SERS that allow it to be used as a chemical sensor also mean that it can be used as a powerful probe of the surface chemistry of any nanostructured material that can provide SERS enhancement. This is important because it is the surface chemistry that controls how these materials interact with their local environment and, in real applications, this interaction can be more important than more commonly measured properties such as morphology or plasmonic absorption. Here, the opportunity that this approach to SERS provides is illustrated with examples where the surface chemistry is both characterized and controlled in order to create functional nanomaterials.
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Affiliation(s)
- Susan Dick
- School of Chemistry and Chemical Engineering, Queen's University, Belfast, BT9 5AG, U.K
| | - Magdalena P Konrad
- School of Chemistry and Chemical Engineering, Queen's University, Belfast, BT9 5AG, U.K
| | - Wendy W Y Lee
- School of Chemistry and Chemical Engineering, Queen's University, Belfast, BT9 5AG, U.K
| | - Hannah McCabe
- School of Chemistry and Chemical Engineering, Queen's University, Belfast, BT9 5AG, U.K
| | - John N McCracken
- School of Chemistry and Chemical Engineering, Queen's University, Belfast, BT9 5AG, U.K
| | - Taifur M D Rahman
- School of Chemistry and Chemical Engineering, Queen's University, Belfast, BT9 5AG, U.K
| | - Alan Stewart
- School of Chemistry and Chemical Engineering, Queen's University, Belfast, BT9 5AG, U.K
| | - Yikai Xu
- School of Chemistry and Chemical Engineering, Queen's University, Belfast, BT9 5AG, U.K
| | - Steven E J Bell
- School of Chemistry and Chemical Engineering, Queen's University, Belfast, BT9 5AG, U.K
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9
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Lee WW, McCoy CP, Donnelly RF, Bell SE. Swellable polymer films containing Au nanoparticles for point-of-care therapeutic drug monitoring using surface-enhanced Raman spectroscopy. Anal Chim Acta 2016; 912:111-6. [DOI: 10.1016/j.aca.2016.01.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 01/11/2016] [Indexed: 11/24/2022]
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10
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Lee WWY, Silverson VAD, Jones LE, Ho YC, Fletcher NC, McNaul M, Peters KL, Speers SJ, Bell SEJ. Surface-enhanced Raman spectroscopy of novel psychoactive substances using polymer-stabilized Ag nanoparticle aggregates. Chem Commun (Camb) 2016; 52:493-6. [DOI: 10.1039/c5cc06745f] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A set of seized “legal high” samples and pure novel psychoactive substances have been examined by surface-enhanced Raman spectroscopy using polymer-stabilized Ag nanoparticle (Poly-SERS) films.
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Affiliation(s)
- W. W. Y. Lee
- Innovative Molecular Materials Group
- School of Chemistry and Chemical Engineering
- Queen's University Belfast
- UK
| | - V. A. D. Silverson
- Innovative Molecular Materials Group
- School of Chemistry and Chemical Engineering
- Queen's University Belfast
- UK
| | - L. E. Jones
- Innovative Molecular Materials Group
- School of Chemistry and Chemical Engineering
- Queen's University Belfast
- UK
| | - Y. C. Ho
- Forensic Science Centre
- New Taipei City Police Department
- New Taipei City
- Republic of China
| | | | - M. McNaul
- Forensic Science Northern Ireland (FSNI)
- Carrickfergus
- UK
| | - K. L. Peters
- Forensic Science Northern Ireland (FSNI)
- Carrickfergus
- UK
| | - S. J. Speers
- School of Veterinary and Life Sciences
- Murdoch University
- Australia
| | - S. E. J. Bell
- Innovative Molecular Materials Group
- School of Chemistry and Chemical Engineering
- Queen's University Belfast
- UK
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11
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Ho YC, Lee WWY, Bell SEJ. Investigation of the chemical origin and evidential value of differences in the SERS spectra of blue gel inks. Analyst 2016; 141:5152-8. [DOI: 10.1039/c6an00972g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Highly swellable polymer films doped with Ag nanoparticle aggregates (poly-SERS films) have been used to record very high signal : noise ratio, reproducible surface-enhanced resonance Raman (SERRS) spectra of in situ dried ink lines and their constituent dyes using both 633 and 785 nm excitation.
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Affiliation(s)
- Yen Cheng Ho
- Forensic Science Centre
- New Taipei City Police Department
- New Taipei City
- Republic of China
| | - Wendy W. Y. Lee
- Innovative Molecular Materials Group
- School of Chemistry and Chemical Engineering
- David Keir Building
- Stranmillis Road
- Queen's University
| | - Steven E. J. Bell
- Innovative Molecular Materials Group
- School of Chemistry and Chemical Engineering
- David Keir Building
- Stranmillis Road
- Queen's University
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12
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Abstract
Latent silver clusters within silver halide films can be developed into SERS active substrates on demand.
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Affiliation(s)
- Pushkaraj Joshi
- Department of Chemical Engineering
- Indian Institute of Science
- Bangalore-560012, India
| | - Venugopal Santhanam
- Department of Chemical Engineering
- Indian Institute of Science
- Bangalore-560012, India
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