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Bui TT, Jang E, Shin JH, Kim TH, Kim H, Choi D, Vu TD, Chung H. Feasibility of Raman spectroscopic identification of gall bladder cancer using extracellular vesicles extracted from bile. Analyst 2023; 148:4156-4165. [PMID: 37501647 DOI: 10.1039/d3an00806a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Extracellular vesicles (EVs), which are heterogeneous membrane-based vesicles with bilayer cell membrane structures, could be versatile biomarkers for the identification of diverse diseases including cancers. With this potential, this study has attempted the Raman spectroscopic identification of gall bladder (GB) cancer by directly measuring the EV solution extracted from human bile without further sample drying. For this purpose, bile samples were obtained from four normal individuals and 21 GB polyp, eight hepatocellular carcinoma (HCC), and five GB cancer patients, and EVs were extracted from each of the bile samples. The Raman peak shapes of the EVs extracted from the GB cancer samples, especially the relative intensities of peaks in the 1560-1340 cm-1 range, were dissimilar to those of the samples from the normal, GB polyp, and HCC groups. The intensity ratios of peaks at 1537 and 1453 cm-1 and at 1395 and 1359 cm-1 of the GB cancer samples were lower and higher, respectively, than those of the samples of the remaining three groups. The differences of peak intensity ratios were statistically significant based on the Mann-Whitney U test. DNA/RNA bases, amino acids, and bile salts contributed to the spectra of EVs, and their relative abundances seemed to vary according to the occurrence of GB cancer. The varied metabolite compositions and/or structures of EVs were successfully demonstrated by the dissimilar peak intensity ratios in the Raman spectra, thereby enabling the discrimination of GB cancer.
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Affiliation(s)
- Thu Thuy Bui
- Department of Chemistry and Research Institute for Convergence of Basic Science, Hanyang University, Seoul 04763, Republic of Korea.
| | - Eunjin Jang
- Department of Chemistry and Research Institute for Convergence of Basic Science, Hanyang University, Seoul 04763, Republic of Korea.
| | - Ji Hyun Shin
- Department of Surgery, College of Medicine, Hanyang University, Seoul 04763, Republic of Korea
| | - Tae Hun Kim
- Department of Surgery, College of Medicine, Hanyang University, Seoul 04763, Republic of Korea
| | - Hayoon Kim
- Department of Surgery, College of Medicine, Hanyang University, Seoul 04763, Republic of Korea
| | - Dongho Choi
- Department of Surgery, College of Medicine, Hanyang University, Seoul 04763, Republic of Korea
| | - Tung Duy Vu
- Faculty of Chemistry, University of Science, Vietnam National University, Hanoi, Vietnam
| | - Hoeil Chung
- Department of Chemistry and Research Institute for Convergence of Basic Science, Hanyang University, Seoul 04763, Republic of Korea.
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Aitekenov S, Sultangaziyev A, Boranova A, Dyussupova A, Ilyas A, Gaipov A, Bukasov R. SERS for Detection of Proteinuria: A Comparison of Gold, Silver, Al Tape, and Silicon Substrates for Identification of Elevated Protein Concentration in Urine. SENSORS (BASEL, SWITZERLAND) 2023; 23:1605. [PMID: 36772644 PMCID: PMC9921516 DOI: 10.3390/s23031605] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/23/2023] [Accepted: 01/24/2023] [Indexed: 06/18/2023]
Abstract
Excessive protein excretion in human urine is an early and sensitive marker of diabetic nephropathy and primary and secondary renal disease. Kidney problems, particularly chronic kidney disease, remain among the few growing causes of mortality in the world. Therefore, it is important to develop an efficient, expressive, and low-cost method for protein determination. Surface enhanced Raman spectroscopy (SERS) methods are potential candidates to achieve these criteria. In this paper, a SERS method was developed to distinguish patients with proteinuria from the healthy group. Commercial gold nanoparticles (AuNPs) with diameters of 60 nm and 100 nm, and silver nanoparticles (AgNPs) with a diameter of 100 nm were tested on the surface of four different substrates including silver and gold films, silicon, and aluminum tape. SERS spectra were acquired from 111 unique human urine samples prepared and measured for each of the seven different nanoparticle plus substrate combinations. Data analysis by the PCA-LDA algorithm and the ROC curves gave results for the diagnostic figures of merits. The best sensitivity, specificity, accuracy, and AUC were 0.91, 0.84, 0.88, and 0.94 for the set with 100 nm Au NPs on the silver substrate, respectively. Among the three metal substrates, the substrate with AuNPs and Al tape performed slightly worse than the other three substrates, and 100 nm gold nanoparticles on average produced better results than 60 nm gold nanoparticles. The 60 nm diameter AuNPs and silicon, which is about one order of magnitude more cost-effective than AuNPs and gold film, showed a relative performance close to the performance of 60 nm AuNPs and Au film (average AUC 0.88 (Si) vs. 0.89 (Au)). This is likely the first reported application of unmodified silicon in SERS substrates applied for direct detection of proteins in any biofluid, particularly in urine. These results position silicon and AuNPs@Si in particular as a perspective SERS substrate for direct urine analysis, including clinical diagnostics of proteinuria.
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Affiliation(s)
- Sultan Aitekenov
- Department of Chemistry, School of Sciences and Humanities (SSH) Nazarbayev University, Nur-Sultan 010000, Kazakhstan
| | - Alisher Sultangaziyev
- Department of Chemistry, School of Sciences and Humanities (SSH) Nazarbayev University, Nur-Sultan 010000, Kazakhstan
| | - Aigerim Boranova
- Department of Chemistry, School of Sciences and Humanities (SSH) Nazarbayev University, Nur-Sultan 010000, Kazakhstan
| | - Aigerim Dyussupova
- Department of Chemistry, School of Sciences and Humanities (SSH) Nazarbayev University, Nur-Sultan 010000, Kazakhstan
| | - Aisha Ilyas
- Department of Chemistry, School of Sciences and Humanities (SSH) Nazarbayev University, Nur-Sultan 010000, Kazakhstan
| | - Abduzhappar Gaipov
- Department of Medicine, School of Medicine, Nazarbayev University, Nur-Sultan 010000, Kazakhstan
| | - Rostislav Bukasov
- Department of Chemistry, School of Sciences and Humanities (SSH) Nazarbayev University, Nur-Sultan 010000, Kazakhstan
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Cui D, Kong L, Wang Y, Zhu Y, Zhang C. In situ identification of environmental microorganisms with Raman spectroscopy. ENVIRONMENTAL SCIENCE AND ECOTECHNOLOGY 2022; 11:100187. [PMID: 36158754 PMCID: PMC9488013 DOI: 10.1016/j.ese.2022.100187] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 05/13/2022] [Accepted: 05/15/2022] [Indexed: 05/28/2023]
Abstract
Microorganisms in natural environments are crucial in maintaining the material and energy cycle and the ecological balance of the environment. However, it is challenging to delineate environmental microbes' actual metabolic pathways and intraspecific heterogeneity because most microorganisms cannot be cultivated. Raman spectroscopy is a culture-independent technique that can collect molecular vibration profiles from cells. It can reveal the physiological and biochemical information at the single-cell level rapidly and non-destructively in situ. The first part of this review introduces the principles, advantages, progress, and analytical methods of Raman spectroscopy applied in environmental microbiology. The second part summarizes the applications of Raman spectroscopy combined with stable isotope probing (SIP), fluorescence in situ hybridization (FISH), Raman-activated cell sorting and genomic sequencing, and machine learning in microbiological studies. Finally, this review discusses expectations of Raman spectroscopy and future advances to be made in identifying microorganisms, especially for uncultured microorganisms.
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Affiliation(s)
- Dongyu Cui
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 511458, China
- Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Lingchao Kong
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science & Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Yi Wang
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 511458, China
- Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Yuanqing Zhu
- Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
- Shanghai Sheshan National Geophysical Observatory, Shanghai Earthquake Agency, Shanghai, 200062, China
| | - Chuanlun Zhang
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 511458, China
- Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
- Shenzhen Key Laboratory of Marine Archaea Geo-Omics, University of Southern University of Science and Technology, Shenzhen, 518055, China
- Shanghai Sheshan National Geophysical Observatory, Shanghai Earthquake Agency, Shanghai, 200062, China
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4
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Hu M, Tang M, Wang H, Zhang M, Zhu S, Yang Z, Zhou S, Zhang H, Hu J, Guo Y, Wei X, Liao Y. Terahertz, infrared and Raman absorption spectra of tyrosine enantiomers and racemic compound. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 254:119611. [PMID: 33689998 DOI: 10.1016/j.saa.2021.119611] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 02/04/2021] [Accepted: 02/07/2021] [Indexed: 05/26/2023]
Abstract
The application of terahertz (THz)-based techniques in biomolecule study is very promising but still in its infancy. In the present work, we employed THz time-domain spectroscopy (THz-TDS) and THz time-domain attenuated total reflection (THz-TD-ATR) spectroscopy to investigate the properties of tyrosine (Tyr) enantiomers (L- and D-Tyr) and racemate (DL-Tyr) in solid state and aqueous solutions, respectively. THz absorption spectra of solid L- and D-Tyr show similar absorption spectra with peaks at 0.95, 1.92, 2.06 and 2.60 THz, which are obviously different from the spectrum of DL-Tyr with peaks at 1.5, 2.15 and 2.40 THz. In contrast, although THz absorption spectra of L-Tyr solution and D-Tyr solution are similar and different from the spectrum of DL-Tyr solution, both of them have no observable peaks. Interestingly, it was found that the solution containing equal amounts of L- and D-Tyr has a similar spectrum as that of DL-Tyr solution, as far as the mass concentrations of the two types of solutions are kept the same. On other hand, solid L-, D- and DL-Tyr were also investigated with infrared spectroscopy and Raman spectroscopy, respectively. The results show that the spectra of L- and D-Tyr can be regarded the same but they are slightly different from the spectrum of DL-Tyr. With the aid of principal component analysis (PCA), the difference between L-/D-Tyr and DL-Tyr can be confirmed without any ambiguity. Overall, this work systematically interrogated and evaluated the performance of THz-based techniques in the detection of the chirality of tyrosine.
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Affiliation(s)
- Meidie Hu
- College of Engineering and Technology, Southwest University, Chongqing 400716, China; Research Center of Applied Physics, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China
| | - Mingjie Tang
- Research Center of Applied Physics, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; Chongqing School, University of Chinese Academy of Sciences, Chongqing 400714, China; Chongqing Engineering Research Center of High-Resolution and Three-Dimensional Dynamic Imaging Technology, Chongqing 400714, China
| | - Huabin Wang
- Research Center of Applied Physics, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; Chongqing School, University of Chinese Academy of Sciences, Chongqing 400714, China; Chongqing Engineering Research Center of High-Resolution and Three-Dimensional Dynamic Imaging Technology, Chongqing 400714, China.
| | - Mingkun Zhang
- Research Center of Applied Physics, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; Chongqing School, University of Chinese Academy of Sciences, Chongqing 400714, China; Chongqing Engineering Research Center of High-Resolution and Three-Dimensional Dynamic Imaging Technology, Chongqing 400714, China
| | - Shiping Zhu
- College of Engineering and Technology, Southwest University, Chongqing 400716, China.
| | - Zhongbo Yang
- Research Center of Applied Physics, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; Chongqing School, University of Chinese Academy of Sciences, Chongqing 400714, China; Chongqing Engineering Research Center of High-Resolution and Three-Dimensional Dynamic Imaging Technology, Chongqing 400714, China
| | - Shengling Zhou
- College of Engineering and Technology, Southwest University, Chongqing 400716, China
| | - Hua Zhang
- Research Center of Applied Physics, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; Chongqing School, University of Chinese Academy of Sciences, Chongqing 400714, China; Chongqing Engineering Research Center of High-Resolution and Three-Dimensional Dynamic Imaging Technology, Chongqing 400714, China
| | - Jiao Hu
- Research Center of Applied Physics, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China
| | - Yuansen Guo
- Research Center of Applied Physics, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China
| | - Xiao Wei
- College of Engineering and Technology, Southwest University, Chongqing 400716, China
| | - Yunsheng Liao
- Research Center of Applied Physics, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China
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Hu J, Zhang D, Zhao H, Sun B, Liang P, Ye J, Yu Z, Jin S. Intelligent spectral algorithm for pigments visualization, classification and identification based on Raman spectra. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 250:119390. [PMID: 33422866 DOI: 10.1016/j.saa.2020.119390] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 12/08/2020] [Accepted: 12/24/2020] [Indexed: 06/12/2023]
Abstract
Raman spectroscopy is a molecular vibrational spectroscopic technique has developed rapidly in recent years, especially in rapid field detection. In this paper, we discuss the Raman spectral pretreatment method and classification algorithm by using nearly 300 pigments spectral data as an example. Here, more than 5 kinds of classification algorithms such as SVM, KNN, ANN and et al are used to sovle the problem of pigments visualization, classification and identification via Raman spectral, and the results show that most of the algorithms fit well, with an accuracy of 90%. Moreover, SNR (Signal to noise ratio) is introduced to evaluate the stability of our algorithm. When the SNR is low, the accuracy of the algorithm decreases sharply. When the SNR was 1, the accuracy rate reached the highest value of 39.46%. In order to slove this problem, the flattopwin, hanning, blackman algorithm was introduced to denoise the signal with low SNR, even when SNR = 1, the signal is 80% accurate. It is proved that in the extreme case of this application, the algorithm still maintains good accuracy, and our research pave the way to use interlligent algorithms to solve the problems in the fields of Raman spectral detection.
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Affiliation(s)
- Jiaqi Hu
- College of Optical and Electronic Technology, China Jiliang University, 310018 Hangzhou, China
| | - De Zhang
- College of Optical and Electronic Technology, China Jiliang University, 310018 Hangzhou, China; Key Laboratory of Urban Agriculture in Central China, College of Horticulture & Forestry Sciences, Huazhong Agricultural University, 430070 Wuhan, China
| | - Hantao Zhao
- College of Optical and Electronic Technology, China Jiliang University, 310018 Hangzhou, China
| | - Biao Sun
- School of Electrical and Information Engineering, Tianjin University, 300000 Tianjin, China
| | - Pei Liang
- College of Optical and Electronic Technology, China Jiliang University, 310018 Hangzhou, China.
| | - Jiaming Ye
- Analysis and Testing Center, Yangtze Delta Region Institute of Tsinghua University, Jiaxing 314006, China
| | - Zhi Yu
- Key Laboratory of Urban Agriculture in Central China, College of Horticulture & Forestry Sciences, Huazhong Agricultural University, 430070 Wuhan, China
| | - Shangzhong Jin
- College of Optical and Electronic Technology, China Jiliang University, 310018 Hangzhou, China
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6
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Ranc V, Chaloupková Z. Chiral discrimination of amino acids using phosphorene assisted graphene-enhanced Raman spectroscopy. Anal Chim Acta 2020; 1129:69-75. [PMID: 32891392 DOI: 10.1016/j.aca.2020.06.067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/27/2020] [Accepted: 06/27/2020] [Indexed: 11/18/2022]
Abstract
Discrimination of enantiomers poses a scientific challenge as the chemical and physical properties of enantiomers are nearly identical. The chiral analysis is usually performed by separation techniques, including chromatography, electrophoresis, or optical instrumentation based on an interaction of the analyzed sample with a polarized beam of light. Here we present a novel method for a chiral screening based on a combination of the black phosphorus@Graphene nanocomposite and Raman spectroscopy. The nanocomposite allows to enhance the Raman signal with factors higher than 100 asymmetrically and provide altered signals for mixtures containing varying enantiomeric ratios of target compounds. Tryptophan, Phenylalanine, DOPA, Isoleucine, and Leucine were selected as model compounds; the method allows us to discriminate between mixtures with 10, 25, 50, 75, and 100% enantiomeric purity.
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Affiliation(s)
- Václav Ranc
- Regional Centre of Advanced Technologies and Materials, Palacký University Olomouc, 17. Listopadu 12, 77146, Olomouc, Czech Republic.
| | - Zuzana Chaloupková
- Regional Centre of Advanced Technologies and Materials, Palacký University Olomouc, 17. Listopadu 12, 77146, Olomouc, Czech Republic
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7
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Deng X, Ali-Adeeb R, Andrews JL, Shreeves P, Lum JJ, Brolo A, Jirasek A. Monitor Ionizing Radiation-Induced Cellular Responses with Raman Spectroscopy, Non-Negative Matrix Factorization, and Non-Negative Least Squares. APPLIED SPECTROSCOPY 2020; 74:701-711. [PMID: 32098482 DOI: 10.1177/0003702820906221] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Radiation therapy (RT) is one of the most commonly prescribed cancer treatments. New tools that can accurately monitor and evaluate individual patient responses would be a major advantage and lend to the implementation of personalized treatment plans. In this study, Raman spectroscopy (RS) was applied to examine radiation-induced cellular responses in H460, MCF7, and LNCaP cancer cell lines across different dose levels and times post-irradiation. Previous Raman data analysis was conducted using principal component analysis (PCA), which showed the ability to extract biological information of glycogen. In the current studies, the use of non-negative matrix factorization (NMF) allowed for the discovery of multiplexed biological information, specifically uncovering glycogen-like and lipid-like component bases. The corresponding scores of glycogen and previously unidentified lipids revealed the content variations of these two chemicals in the cellular data. The NMF decomposed glycogen and lipid-like bases were able to separate the cancer cell lines into radiosensitive and radioresistant groups. A further lipid phenotype investigation was also attempted by applying non-negative least squares (NNLS) to the lipid-like bases decomposed individually from three cell lines. Qualitative differences found in lipid weights for each lipid-like basis suggest the lipid phenotype differences in the three tested cancer cell lines. Collectively, this study demonstrates that the application of NMF and NNLS on RS data analysis to monitor ionizing radiation-induced cellular responses can yield multiplexed biological information on bio-response to RT not revealed by conventional chemometric approaches.
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Affiliation(s)
- Xinchen Deng
- Department of Physics, I.K. Barber School of Arts and Sciences, The University of British Columbia, Kelowna, Canada
| | - Ramie Ali-Adeeb
- Department of Physics, I.K. Barber School of Arts and Sciences, The University of British Columbia, Kelowna, Canada
| | - Jeffrey L Andrews
- Department of Statistics, I.K. Barber School of Arts and Sciences, The University of British Columbia, Kelowna, Canada
| | - Phillip Shreeves
- Department of Statistics, I.K. Barber School of Arts and Sciences, The University of British Columbia, Kelowna, Canada
| | - Julian J Lum
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, Canada
- Trev and Joyce Deeley Research Centre, BC Cancer, Victoria, Canada
| | - Alexandre Brolo
- Department of Chemistry, University of Victoria, Victoria, Canada
| | - Andrew Jirasek
- Department of Physics, I.K. Barber School of Arts and Sciences, The University of British Columbia, Kelowna, Canada
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Rullich CC, Kiefer J. Principal component analysis to enhance enantioselective Raman spectroscopy. Analyst 2019; 144:2080-2086. [PMID: 30734784 DOI: 10.1039/c8an01886c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Enantioselective Raman (esR) spectroscopy is an innovative technique with a high potential for online process monitoring in chiral media, e.g. in the pharmaceutical industry. A prerequisite for an effective application is to combine the experimental approach with suitable concepts for data analysis. In this work, we present a chemometric approach to analyze the esR spectra recorded in an automatized polarization-resolved Raman set-up. It is demonstrated that the proposed method is capable of distinguishing between the enantiomers of the chiral alcohol 4-methylpentan-2-ol in a fully unsupervised fashion. Furthermore, it is shown that the difficulty of facing only small intensity differences between the esR spectra of the enantiomers can be overcome by feeding difference spectra between the pure enantiomers and the racemate into the principal component analysis (PCA) algorithm. The enantiomers are clearly discriminable along the first principal component.
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Affiliation(s)
- Claudia C Rullich
- Technische Thermodynamik, Universität Bremen, Badgasteiner Str. 1, 28359 Bremen, Germany
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9
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Rullich CC, Kiefer J. Enantioselective Raman spectroscopy (esR) for distinguishing between the enantiomers of 2-butanol. Analyst 2018; 143:3040-3048. [PMID: 29878000 DOI: 10.1039/c8an00705e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The first experimental application of enantioselective Raman spectroscopy (esR) is demonstrated using the example of the chiral alcohol 2-butanol. Samples of the neat enantiomers and the racemic mixture were analyzed in a self-built Raman set-up. The Raman spectrum allows the discrimination of the chemical species. It is shown that the optical rotation of a Raman peak with a small depolarization ratio can be measured. In addition, without any sample modification, e.g. chiral solvent, the enantiomers are distinguishable at a suitable half-wave retarder angle detecting only the vertically polarized component of the Raman signal.
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Affiliation(s)
- Claudia C Rullich
- University of Bremen, Technische Thermodynamik, Badgasteiner Str. 1, 28359 Bremen, Germany
| | - Johannes Kiefer
- University of Bremen, Technische Thermodynamik, Badgasteiner Str. 1, 28359 Bremen, Germany and University of Bremen, MAPEX Center for Materials and Processes, 28359 Bremen, Germany.
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