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Ma Q, Chu W, Nong X, Zhao J, Liu H, Du Q, Sun J, Shen J, Lu SM, Lin M, Huang Y, Xia F. Local Electric Potential-Driven Nanofluidic Ion Transport for Ultrasensitive Biochemical Sensing. ACS Nano 2024; 18:6570-6578. [PMID: 38349220 DOI: 10.1021/acsnano.3c12547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
Nanofluidic biosensors have been widely used for detection of analytes based on the change of system resistance before and after target-probe interactions. However, their sensitivity is limited when system resistance barely changes toward low-concentration targets. Here, we proposed a strategy to address this issue by means of target-induced change of local membrane potential under relatively unchanged system resistance. The local membrane potential originated from the directional diffusion of photogenerated carriers across nanofluidic biosensors and gated photoinduced ionic current signal before and after target-probe interactions. The sensitivity of such biosensors for the detection of biomolecules such as circulating tumor DNA (ctDNA) and lysozyme exceeds that of applying a traditional strategy by more than 3 orders of magnitude under unchanged system resistance. Such biosensors can specifically detect the small molecule biomarker in the blood sample between prostate cancer patients and healthy humans. The key advantages of such nanofluidic biosensors are therefore complementary to traditional nanofluidic biosensors, with potential applications in a point-of-care analytical tool.
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Affiliation(s)
- Qun Ma
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, P. R. China
- Department of Chemical Engineering, Graduate School of Engineering, Osaka Metropolitan University, Osaka 599-8531, Japan
| | - Wenjing Chu
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, P. R. China
| | - Xianliang Nong
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, P. R. China
| | - Jing Zhao
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, P. R. China
| | - Hong Liu
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, P. R. China
| | - Qiujiao Du
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, P. R. China
| | - Jielin Sun
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Jianlei Shen
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and National Center for Translational Medicine, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Si-Min Lu
- Molecular Sensing and Imaging Center, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China
| | - Meihua Lin
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, P. R. China
| | - Yu Huang
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, P. R. China
| | - Fan Xia
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, P. R. China
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Wang Q, Panpradist N, Kotnik JH, Willson RC, Kourentzi K, Chau ZL, Liu JK, Lutz BR, Lai JJ. A simple agglutination system for rapid antigen detection from large sample volumes with enhanced sensitivity. Anal Chim Acta 2023; 1277:341674. [PMID: 37604625 PMCID: PMC10777812 DOI: 10.1016/j.aca.2023.341674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 07/14/2023] [Accepted: 07/29/2023] [Indexed: 08/23/2023]
Abstract
Lateral flow assays (LFAs) provide a simple and quick option for diagnosis and are widely adopted for point-of-care or at-home tests. However, their sensitivity is often limited. Most LFAs only allow 50 μL samples while various sample types such as saliva could be collected in much larger volumes. Adapting LFAs to accommodate larger sample volumes can improve assay sensitivity by increasing the number of target analytes available for detection. Here, a simple agglutination system comprising biotinylated antibody (Ab) and streptavidin (SA) is presented. The Ab and SA agglutinate into large aggregates due to multiple biotins per Ab and multiple biotin binding sites per SA. Dynamic light scattering (DLS) measurements showed that the agglutinated aggregate could reach a diameter of over 0.5 μm and over 1.5 μm using poly-SA. Through both experiments and Monte Carlo modeling, we found that high valency and equivalent concentrations of the two aggregating components were critical for successful agglutination. The simple agglutination system enables antigen capture from large sample volumes with biotinylated Ab and a swift transition into aggregates that can be collected via filtration. Combining the agglutination system with conventional immunoassays, an agglutination assay is proposed that enables antigen detection from large sample volumes using an in-house 3D-printed device. As a proof-of-concept, we developed an agglutination assay targeting SARS-CoV-2 nucleocapsid antigen for COVID-19 diagnosis from saliva. The assay showed a 10-fold sensitivity enhancement when increasing sample volume from 50 μL to 2 mL, with a final limit of detection (LoD) of 10 pg mL-1 (∼250 fM). The assay was further validated in negative saliva spiked with gamma-irradiated SARS-CoV-2 and showed an LoD of 250 genome copies per μL. The proposed agglutination assay can be easily developed from existing LFAs to facilitate the processing of large sample volumes for improved sensitivity.
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Affiliation(s)
- Qin Wang
- Department of Bioengineering, University of Washington, Seattle, WA, 98195-5061, USA
| | - Nuttada Panpradist
- Department of Bioengineering, University of Washington, Seattle, WA, 98195-5061, USA
| | - Jack Henry Kotnik
- Department of Bioengineering, University of Washington, Seattle, WA, 98195-5061, USA
| | - Richard C Willson
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX, 77204, USA
| | - Katerina Kourentzi
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX, 77204, USA
| | - Zoe L Chau
- Department of Bioengineering, University of Washington, Seattle, WA, 98195-5061, USA
| | - Joanne K Liu
- Department of Bioengineering, University of Washington, Seattle, WA, 98195-5061, USA
| | - Barry R Lutz
- Department of Bioengineering, University of Washington, Seattle, WA, 98195-5061, USA.
| | - James J Lai
- Department of Bioengineering, University of Washington, Seattle, WA, 98195-5061, USA; Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei, 106335, Taiwan.
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Christopoulou NM, Kalogianni DP, Christopoulos TK. Multifold improvement in allergen detection capability of dipstick-type immunosensors via macromolecular crowding. Talanta 2023; 265:124899. [PMID: 37421795 DOI: 10.1016/j.talanta.2023.124899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 06/22/2023] [Accepted: 07/01/2023] [Indexed: 07/10/2023]
Abstract
Dipstick-type lateral flow immunosensors are used widely for on-site detection of food allergens. The weakness of the immunosensors of this type, however, is their low sensitivity. Contrary to current methods, that focus on improving detection capability through the introduction of novel labels or multistep protocols, this work exploits macromolecular crowding to modify and regulate the microenvironment of the immunoassay, thus promoting the interactions that are responsible for allergen recognition and signal generation. The effect of 14 macromolecular crowding agents was explored using, as a model, commercially available and widely applied dipstick immunosensors, which are already optimized in terms of reagents and conditions for peanut allergen detection. An about 10-fold improvement in detection capability was achieved by using polyvinylpyrrolidone, Mr 29,000, as a macromolecular crowder without compromising simplicity and practicality. The proposed approach is complementary to other methods of improving the sensitivity by using novel labels. Because biomacromolecular interactions have a fundamental role in all types of biosensors, we foresee that the proposed strategy will also find applications in other biosensors and analytical devices.
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Affiliation(s)
- Natalia-Maria Christopoulou
- Analytical/Bioanalytical Chemistry & Nanotechnology Group, Department of Chemistry, University of Patras, Rio, Patras, 26504, Greece
| | - Despina P Kalogianni
- Analytical/Bioanalytical Chemistry & Nanotechnology Group, Department of Chemistry, University of Patras, Rio, Patras, 26504, Greece
| | - Theodore K Christopoulos
- Analytical/Bioanalytical Chemistry & Nanotechnology Group, Department of Chemistry, University of Patras, Rio, Patras, 26504, Greece.
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Tan J, Chen Y, He J, Occhipinti LG, Wang Z, Zhou X. Two-dimensional material-enhanced surface plasmon resonance for antibiotic sensing. J Hazard Mater 2023; 455:131644. [PMID: 37209558 DOI: 10.1016/j.jhazmat.2023.131644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 05/12/2023] [Accepted: 05/13/2023] [Indexed: 05/22/2023]
Abstract
Two-dimensional (2D) materials attract attention from the academic community due to their excellent properties, and their wide application in sensing is expected to revolutionize environmental monitoring, medical diagnostics, and food safety. In this work, we systematically evaluate the effects of 2D materials on the Au chip surface plasmon resonance (SPR) sensor. The results reveal that 2D materials cannot improve the sensitivity of intensity-modulated SPR sensors. However, there exists an optimal real part of RI of 3.5-4.0 and optimal thickness when choosing nanomaterials for sensitivity enhancement of SPR sensors in angular modulation. In addition, the smaller the imaginary part of the nanomaterial RI, the higher the sensitivity of the proposed Au SPR sensor. The 2D material's thickness needed for the highest sensitivity decreases with increasing real part and imaginary part of the RI. As a case study, we developed a 5 nm-thickness MoS2-enhanced SPR biosensor, which exhibited a low sulfonamides (SAs) detection limit of 0.05 μg/L based on a group-targeting indirect competitive immunoassay, nearly 12-fold lower than that of the bare Au SPR system. The proposed criteria help to shed light on the 2D material-Au surface interaction, which has greatly promoted the development of novel SPR biosensing with outstanding sensitivity.
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Affiliation(s)
- Jisui Tan
- State Key Joint Laboratory of ESPC, School of Environment, Tsinghua University, Beijing 100084, China
| | - Yangyang Chen
- State Key Joint Laboratory of ESPC, School of Environment, Tsinghua University, Beijing 100084, China
| | - Jing He
- Cambridge Graphene Centre, Department of Engineering, University of Cambridge, Cambridge CB3 0FA, United Kingdom
| | - Luigi G Occhipinti
- Cambridge Graphene Centre, Department of Engineering, University of Cambridge, Cambridge CB3 0FA, United Kingdom
| | - Zhanhui Wang
- College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Xiaohong Zhou
- State Key Joint Laboratory of ESPC, School of Environment, Tsinghua University, Beijing 100084, China.
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Jin B, Du Z, Ji J, Bai Y, Tang D, Qiao L, Lou J, Hu J, Li Z. Regulation of probe density on upconversion nanoparticles enabling high-performance lateral flow assays. Talanta 2023; 256:124327. [PMID: 36758506 DOI: 10.1016/j.talanta.2023.124327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 01/17/2023] [Accepted: 02/03/2023] [Indexed: 02/09/2023]
Abstract
Upconversion nanoparticles (UCNPs)-based fluorescence probes have shown great potential in point-of-care testing (POCT) applications, due to UCNPs' features of high photostability and background-free fluorescence. Ceaseless improvements of UCNPs-probes have been carried out to increase detection sensitivity and to broaden detection range of UCNPs-based POCT. In this paper, we optimized UCNPs-probes by regulating probe density. The optimization was verified by a traditional lateral flow assay (LFA) platform for C-reactive protein (CRP) detection. Further, the optimized UCNPs-LFA integrating with a home-made benchtop fluorescence analyzer holds the capability to achieve high-performance POCT. Finally, nearly a 20 times sensitivity enhancement with a limit of detection of 0.046 ng/mL and a broad detection range of 0.2-300 ng/mL for CRP detection was obtained. Moreover, the optimized UCNPs-LFA was applied to detecting CRP in clinical serum samples and the detection results were consistent with the clinical test, validating its clinical practicability. The proposed optimization method is also expected to optimize other nanoparticles-based bio-probes for wider POCT application.
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Affiliation(s)
- Birui Jin
- School of Materials and Chemical Engineering, Xi'an Technological University, Xi'an, 710021, China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, 710049, China
| | - Zhiguo Du
- School of Materials and Chemical Engineering, Xi'an Technological University, Xi'an, 710021, China
| | - Jingcheng Ji
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Xi'an Jiaotong University, Xi'an, 710049, China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, 710049, China
| | - Yuemeng Bai
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Xi'an Jiaotong University, Xi'an, 710049, China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, 710049, China
| | - Deding Tang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Xi'an Jiaotong University, Xi'an, 710049, China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, 710049, China; Maanshan Teachers College, Ma Anshan, 243041, China
| | - Lihua Qiao
- Department of Laboratory Medicine, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Jiatao Lou
- Department of Laboratory Medicine, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, 200030, China; Department of Laboratory Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, China
| | - Jie Hu
- Suzhou DiYinAn Biotech Co., Ltd., Suzhou Innovation Center for Life Science and Technology, Suzhou, 215129, China.
| | - Zedong Li
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Xi'an Jiaotong University, Xi'an, 710049, China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, 710049, China.
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Murariu M, Stroea L. Increasing detection sensitivity of fluorescent polymeric sensors containing fluorescein derivatives by Au NPs. Spectrochim Acta A Mol Biomol Spectrosc 2023; 291:122279. [PMID: 36646041 DOI: 10.1016/j.saa.2022.122279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 11/30/2022] [Accepted: 12/24/2022] [Indexed: 06/17/2023]
Abstract
New fluorescent polymeric sensors containing in situ photogenerated gold nanoparticles (Au NPs) and fluorescein-based copolymers are reported. They are tested as efficient fluorescent chemosensors for the sensitive detection of toxic divalent metal ions, such as Co2+, Cu2+, Cd2+, (UO2)2+, Pb2+, Zn2+and Hg2+. Their fluorescence quenching process depends on the concentration of metal cations and is comparatively analyzed for both the starting copolymers and the corresponding hybrid materials. Thus, the best results are recorded for uranyl (4 × 10-6 M) and copper ions (16 × 10-6 M), respectively. The detection limits of the investigated hybrid materials are lower by an order of magnitude compared to the starting copolymers, while the fluorescence quenching mechanism mainly occurred by a dynamic process, following a linear Stern-Volmer relationship. Thus, the report fundamentally confirms the influence of small amounts of Au NP (2 wt%) on the improved sensitivity of the final fluorescent sensors.
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Affiliation(s)
- Mioara Murariu
- Department of Polyaddition and Photochemistry, Petru Poni Institute of Macromolecular Chemistry, 41 A Grigore Ghica Voda Alley, 700487 Iasi, Romania.
| | - Lenuta Stroea
- Department of Polyaddition and Photochemistry, Petru Poni Institute of Macromolecular Chemistry, 41 A Grigore Ghica Voda Alley, 700487 Iasi, Romania
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Yanagisawa K, Matsueda M, Furukawa M, Takagai Y. Sensitivity enhancement in inductively coupled plasma mass spectrometry using nebulization methods via nitrogen mixed gas effect. ANAL SCI 2022. [PMID: 35713872 DOI: 10.1007/s44211-022-00140-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 05/24/2022] [Indexed: 11/01/2022]
Abstract
We demonstrate the sensitivity enhancement in inductively coupled plasma mass spectrometry (ICP-MS) by combining ultrasonic nebulization via the nitrogen mixed gas effect. We showed the effect of nitrogen gas concentration (0-5%) in the nebulizer gas on the signal sensitivity for 63 elements using commercially available (concentric and ultrasonic) nebulizers. In addition, the limit of detection (ng L-1) was calculated in each case. Finally, we compared the sensitivity (i.e., the slope of the calibration curve), background noise intensity, and three-dimensional intensity distribution in the plasma to elucidate the effects of the concurrent use of mixed gas plasmas and nebulization methods.
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Suntornsuk L, Anurukvorakun O. Sensitivity enhancement in capillary electrophoresis and their applications for analyses of pharmaceutical and related biochemical substances. Electrophoresis 2021; 43:939-954. [PMID: 34902168 DOI: 10.1002/elps.202100236] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 11/23/2021] [Accepted: 11/30/2021] [Indexed: 11/11/2022]
Abstract
This review aims to illustrate sensitivity enhancement methods in capillary electrophoresis (CE) and their applications for pharmaceutical and related biochemical substance analyses. The first two parts of the article describe the introduction and principle of CE. The main part focuses on strategies for sensitivity improvement in CE including detector and capillary technologies and pre-concentration techniques. Applications of these techniques for pharmaceutical and biomedical substance analyses are surveyed during the years 2018-2021. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Leena Suntornsuk
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Mahidol University, Bangkok, 10400, Thailand
| | - Oraphan Anurukvorakun
- Department of Cosmetic Science, Phranakorn Rajabhat University, Bangkok, 10220, Thailand
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You T, Jeong W, Lee H, Huh YS, Kim SM, Jeon TJ. A simple strategy for signal enhancement in lateral flow assays using superabsorbent polymers. Mikrochim Acta 2021; 188:364. [PMID: 34613450 DOI: 10.1007/s00604-021-05026-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 09/11/2021] [Indexed: 10/20/2022]
Abstract
To enhance the sensitivity of lateral flow assays (LFAs), a simple strategy is proposed using a nitrocellulose membrane modified with a superabsorbent polymer (SAP). SAP was incorporated into a nitrocellulose membrane for the flow control of detection probes. When absorbing aqueous solutions, SAP promoted the formation of biomolecule complexes to achieve up to a tenfold sensitivity improvement for the detection of human IgG. The assay time was optimized experimentally and numerically to within 20 min using this strategy. Moreover, fluid saturation in LFAs modified with SAP was mathematically simulated to better understand the underlying process, and molecular dynamics simulations were carried out to determine the effect of SAP. The proposed design was also applied to samples spiked with human immunoglobulin-depleted serum to test its applicability. The strategy presented is unique in that it preserves the characteristics of conventional LFAs, as it minimizes user intervention and is simple to manufacture at scale.
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Affiliation(s)
- Taeyeong You
- Department of Biological Sciences and Bioengineering, Inha University, Incheon, 22212, South Korea.,Biohybrid Systems Research Center (BSRC), Inha University, Incheon, 22212, South Korea
| | - Woojin Jeong
- Department of Biological Sciences and Bioengineering, Inha University, Incheon, 22212, South Korea.,Biohybrid Systems Research Center (BSRC), Inha University, Incheon, 22212, South Korea
| | - Hwankyu Lee
- Department of Chemical Engineering, Dankook University, Yongin, 16890, South Korea
| | - Yun Suk Huh
- Department of Biological Sciences and Bioengineering, Inha University, Incheon, 22212, South Korea. .,Biohybrid Systems Research Center (BSRC), Inha University, Incheon, 22212, South Korea. .,Department of Biological Engineering, Inha University, Incheon, 22212, South Korea.
| | - Sun Min Kim
- Department of Biological Sciences and Bioengineering, Inha University, Incheon, 22212, South Korea. .,Biohybrid Systems Research Center (BSRC), Inha University, Incheon, 22212, South Korea. .,Department of Mechanical Engineering, Inha University, Incheon, 22212, South Korea.
| | - Tae-Joon Jeon
- Department of Biological Sciences and Bioengineering, Inha University, Incheon, 22212, South Korea. .,Biohybrid Systems Research Center (BSRC), Inha University, Incheon, 22212, South Korea. .,Department of Biological Engineering, Inha University, Incheon, 22212, South Korea.
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10
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Tang R, Alam N, Li M, Xie M, Ni Y. Dissolvable sugar barriers to enhance the sensitivity of nitrocellulose membrane lateral flow assay for COVID-19 nucleic acid. Carbohydr Polym 2021; 268:118259. [PMID: 34127229 DOI: 10.1016/j.carbpol.2021.118259] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 05/07/2021] [Accepted: 05/21/2021] [Indexed: 12/21/2022]
Abstract
Nitrocellulose (NC) membrane can have value-added applications for lateral flow assay (LFA)-based diagnostic tools, which has great potential for the detection of pathogens, such as COVID-19, in different environments. However, poor sensitivity of the NC membrane based LFA limits its further application in many cases. Herein, we developed a facile method for LFA sensitivity enhancement, by incorporating two-sugar barrier into LFAs: one between the conjugation pad and the test line, and the other between the test line and the control line. ORF1ab nucleic acid of COVID-19 was used as the model target to demonstrate the concept on the HF120 membrane. Results show that at optimum conditions, the two sugar barrier LFAs have a detection limit of 0.5 nM, which is compared to that of 2.5 nM for the control LFA, achieving a 5-fold sensitivity increase. This low cost, easy-to-fabricate and easy-to-integrate LFA method may have potential applications in other cellulose paper-based platforms.
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Affiliation(s)
- Ruihua Tang
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science & Technology, Xi'an 710021, PR China; Limerick Pulp and Paper Centre, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada.
| | - Nur Alam
- Limerick Pulp and Paper Centre, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada
| | - Min Li
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science & Technology, Xi'an 710021, PR China
| | - Mingyue Xie
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science & Technology, Xi'an 710021, PR China
| | - Yonghao Ni
- Limerick Pulp and Paper Centre, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada.
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Yang H, Mecha MF, Goebel CP, Cavagnero S. Enhanced nuclear-spin hyperpolarization of amino acids and proteins via reductive radical quenchers. J Magn Reson 2021; 324:106912. [PMID: 33524671 PMCID: PMC7925436 DOI: 10.1016/j.jmr.2021.106912] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 01/04/2021] [Accepted: 01/05/2021] [Indexed: 06/12/2023]
Abstract
Low-concentration photochemically induced dynamic nuclear polarization (LC-photo-CIDNP) has recently emerged as an effective tool for the hyperpolarization of aromatic amino acids in solution, either in isolation or within proteins. One factor limiting the maximum achievable signal-to-noise ratio in LC-photo-CIDNP is the progressive degradation of the target molecule and photosensitizer upon long-term optical irradiation. Fortunately, this effect does not cause spectral distortions but leads to a progressively smaller signal buildup upon long-term data-collection (e.g. 500 nM tryptophan on a 600 MHz spectrometer after ca. 200 scans). Given that it is generally desirable to minimize the extent of photodamage, we report that low-μM amounts of the reductive radical quenchers vitamin C (VC, i.e., ascorbic acid) or 2-mercaptoethylamine (MEA) enable LC-photo-CIDNP data to be acquired for significantly longer time than ever possible before. This approach increases the sensitivity of LC-photo-CIDNP by more than 100%, with larger enhancement factors achieved in experiments involving more transients. Our results are consistent with VC and MEA acting primarily by reducing transient free radicals of the NMR molecule of interest, thus attenuating the extent of photodamage. The benefits of this reductive radical-quencher approach are highlighted by the ability to collect long-term high-resolution 2D 1H-13C LC-photo-CIDNP data on a dilute sample of the drkN SH3 protein (5 μM).
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Affiliation(s)
- Hanming Yang
- Department of Chemistry, University of Wisconsin - Madison, 1101 University Ave, Madison, WI 53706, USA
| | - Miranda F Mecha
- Department of Chemistry, University of Wisconsin - Madison, 1101 University Ave, Madison, WI 53706, USA
| | - Collin P Goebel
- Department of Chemistry, University of Wisconsin - Madison, 1101 University Ave, Madison, WI 53706, USA
| | - Silvia Cavagnero
- Department of Chemistry, University of Wisconsin - Madison, 1101 University Ave, Madison, WI 53706, USA.
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Ozdemir S, Kılınç E, Şen F, Soylak M. Development of Armillae mellea immobilized nanodiamond for the preconcentrations of Cr(III), Hg(II) and Zn(II). Anal Biochem 2021; 617:114122. [PMID: 33515499 DOI: 10.1016/j.ab.2021.114122] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 01/22/2021] [Accepted: 01/24/2021] [Indexed: 01/13/2023]
Abstract
In this study, we present an environmental friend and easy procedure for simultaneous preconcentration of Cr(III), Hg(II) and Zn(II) by solid-phase extraction before their determination by inductively coupled plasma optical emission spectrometry. Armillae mellea immobilized nanodiamond was used as sorbent. During the study, critical parameters influencing the extraction performance were investigated in detail. The best parameters were found as pH 5.0, 2.0 mL min-1 of flow rate, 200 mg of Armillae mellea, 300 mL of sample volume. LOD values were found as 0.025, 0.13 and 0.038 ng mL-1, respectively for Cr(III), Hg(II) and Zn(II). By applying the developed procedure, sensitivities of ICP-OES were improved for 60 fold for Cr(III), Hg(II) and Zn(II). Their concentrations in different food samples were measured after microwave digestion and solid-phase extraction.
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Affiliation(s)
- Sadin Ozdemir
- Department of Food Processing, Technical Science Vocational School, Mersin University, TR-33343 Yenisehir, Mersin, Turkey
| | - Ersin Kılınç
- Health Services Vocational High School, Medical Marketing and Promotion Programme, Mardin Artuklu University, 47200 Mardin, Turkey.
| | - Fatih Şen
- Sen Research Group, Department of Biochemistry, Faculty of Art and Science, Dumlupinar University, Turkey.
| | - Mustafa Soylak
- Department of Chemistry, Faculty of Science, Erciyes University, TR-38039 Kayseri, Turkey
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13
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Furuita K, Sugiki T, Takamuku M, Hattori Y, So M, Kawata Y, Ikegami T, Fujiwara T, Kojima C. Sensitivity enhancement by sequential data acquisition for 13C-direct detection NMR. J Magn Reson 2021; 322:106878. [PMID: 33285399 DOI: 10.1016/j.jmr.2020.106878] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 11/19/2020] [Accepted: 11/23/2020] [Indexed: 06/12/2023]
Abstract
13C-direct detection NMR has several advantages compared to proton detection, including a tendency to relax slower and wider chemical shift range. However, the sensitivity of 13C-direct detection is much lower than that of proton detection because of its lower gyromagnetic ratio. In addition, a virtual decoupling procedure is often performed to remove peak splitting in the 13C-direct detection axis, which further reduces the sensitivity to 1/√2. In this study, to enhance the sensitivity of 13C-direct detection experiments, we developed a HCACO-type new pulse sequence in which anti-phase (AP) and in-phase (IP) signals are acquired sequentially in a single scan. The developed experiment was tested on an amino acid (valine) and two proteins (streptococcal protein G B1 domain (GB1) and α-synuclein). The AP and IP spectra were successfully obtained in all cases. Using these spectra, IPAP virtual decoupling was performed, and peak splitting was successfully removed. The sensitivity of the experiment was increased by 1.43, 1.26 and 1.26 times for valine, GB1 and α-synuclein, respectively, compared to the conventional HCACO experiment. In addition, we developed another HCACO-type pulse sequence, where AP and IP signals are simultaneously acquired in a single FID. The sensitivity of the experiment was increased by 1.40 and 1.35 times for valine and GB1, respectively. These methods are potentially applicable to other 13C-direct detection experiments that measure one-bond correlations and will further extend the utility of the 13C-direct detection method, especially for structural analyses of intrinsically disordered proteins.
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Affiliation(s)
- Kyoko Furuita
- Institute for Protein Research, Osaka University, Japan.
| | | | - Mika Takamuku
- Institute for Protein Research, Osaka University, Japan
| | - Yoshikazu Hattori
- Institute for Protein Research, Osaka University, Japan; Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Japan
| | - Masatomo So
- Institute for Protein Research, Osaka University, Japan
| | - Yasushi Kawata
- Graduate School of Engineering, Tottori University, Japan
| | - Takahisa Ikegami
- Institute for Protein Research, Osaka University, Japan; Graduate School of Medical Life Science, Yokohama City University, Japan
| | | | - Chojiro Kojima
- Institute for Protein Research, Osaka University, Japan; Graduate School of Engineering Science, Yokohama National University, Japan.
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14
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Abstract
Conventional lateral flow assay (LFA) is typically performed by observing the color changes in the test lines by naked eyes, which achieves considerable commercial success and has a significant impact on the fields of food safety, environment monitoring, disease diagnosis, and other applications. However, this qualitative detection method is not very suitable for low levels of disease biomarkers' detection. Although many nanomaterials are used as new labels for LFA, additional readers limit their application to some extent. Fortunately, a lot of work has been done for improving the sensitivity of LFA. In this review, currently reported LFA sensitivity enhancement methods with an objective evaluation are summarized, such as sample pretreatment, the change of flow rate, and label evolution, and future development direction and challenges of LFAs are discussed.
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15
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Alam N, Tong L, He Z, Tang R, Ahsan L, Ni Y. Improving the sensitivity of cellulose fiber-based lateral flow assay by incorporating a water-dissolvable polyvinyl alcohol dam. Cellulose (Lond) 2021; 28:8641-8651. [PMID: 34305338 PMCID: PMC8286161 DOI: 10.1007/s10570-021-04083-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 07/12/2021] [Indexed: 05/09/2023]
Abstract
UNLABELLED Lateral flow assay (LFA) is an important point-of-care (POC) test platform due to the associated portability, on-site testing, and low cost for diagnosis of pathogen infections and disease biomarkers. However, compared to high-end analyzers in hospitals, LFA devices, in particular, paper- based LFA tests, fall short in accuracy. This study focuses on two ways to improve LFAs: (1) using cellulose fibers, rather than glass fibers for a sample pad, and (2) incorporating a one-step simple, facile, and low cost PVA dam into the LFA. Both strategies (cellulose fiber as a sample pad and water dissolvable PVA dam) contributed to delaying the controlled biomolecule's flow through the nitrocellulose membrane's capillary channels resulting in increased bio-recognition time, thus contributing to the enhancement of LFA sensitivity. PVA modified cellulose fiber-based LFA demonstrated 10 times higher sensitivity than the cellulose fiber-based unmodified LFA, whereas 2 times enhancement was obtained in the cellulose fiber-based sample pad LFA compared to the glass fiber-based sample pad LFA. Ultimately, 20 times increase in sensitivity was achieved in the modified LFA device. This study shows that PVA and eco-friendly cellulose fibers could be incorporated into other paper based POC testing devices for future development. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s10570-021-04083-3.
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Affiliation(s)
- Nur Alam
- Department of Chemical Engineering, University of New Brunswick, Fredericton, NB E3B 5A3 Canada
| | - Li Tong
- Department of Chemical Engineering, University of New Brunswick, Fredericton, NB E3B 5A3 Canada
| | - Zhibin He
- Department of Chemical Engineering, University of New Brunswick, Fredericton, NB E3B 5A3 Canada
| | - Ruihua Tang
- Department of Chemical Engineering, University of New Brunswick, Fredericton, NB E3B 5A3 Canada
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science & Technology, Xi’an, 710021 People’s Republic of China
| | - Laboni Ahsan
- Labaid Ltd (Diagonestic and Reference Lab), Dhanmondi, Dhaka, Bangladesh
| | - Yonghao Ni
- Department of Chemical Engineering, University of New Brunswick, Fredericton, NB E3B 5A3 Canada
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16
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Long Z, Opella SJ. 1H detection of heteronuclear dipolar oscillations with water suppression in single crystal peptide and oriented protein samples. J Magn Reson 2020; 318:106793. [PMID: 32827996 PMCID: PMC8132951 DOI: 10.1016/j.jmr.2020.106793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 07/02/2020] [Accepted: 07/13/2020] [Indexed: 06/11/2023]
Abstract
Oriented sample solid-state NMR is a complementary approach to protein structure determination with the distinct advantage that it can be applied to supramolecular assemblies, such as viruses and membrane proteins, under near-native conditions, which generally include high levels of hydration as found in living systems. Thus, in order to perform 1H detected versions of multi-dimensional experiments water suppression techniques must be integrated into the pulse sequences. For example, 1H-windowed detection of 1H-15N dipolar couplings enable multi-dimensional NMR experiments to be performed. Here we show that the addition of a solvent suppression pulse during the z-filter interval greatly improves the sensitivity of the experiments by suppressing the 1H signals from water present. This is demonstrated here with a crystal sample submerged in water and then extended to proteins. The combination of solvent-suppressed 1H detected PISEMO and the use of a strip shield-solenoid coil probe configuration provides a two-fold sensitivity enhancement in both the crystal sample and Pf1 coat protein sample compared to the 15N direct detection method. Here we also examine protein NMR line-widths and sensitivity enhancements in the context of window detected separated local field experiments for protein samples.
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Affiliation(s)
- Zheng Long
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0307, United States
| | - Stanley J Opella
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0307, United States.
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17
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Sena-Torralba A, Ngo DB, Parolo C, Hu L, Álvarez-Diduk R, Bergua JF, Rosati G, Surareungchai W, Merkoçi A. Lateral flow assay modified with time-delay wax barriers as a sensitivity and signal enhancement strategy. Biosens Bioelectron 2020; 168:112559. [PMID: 32890932 DOI: 10.1016/j.bios.2020.112559] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 08/24/2020] [Indexed: 02/08/2023]
Abstract
The ease of use, low cost and quick operation of lateral flow assays (LFA) have made them some of the most common point of care biosensors in a variety of fields. However, their generally low sensitivity has limited their use for more challenging applications, where the detection of low analytic concentrations is required. Here we propose the use of soluble wax barriers to selectively and temporarily accumulate the target and label nanoparticles on top of the test line (TL). This extended internal incubation step promotes the formation of the immune-complex, generating a 51.7-fold sensitivity enhancement, considering the limit of quantification, and up to 96% signal enhancement compared to the conventional LFA for Human IgG (H-IgG) detection.
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Affiliation(s)
- Amadeo Sena-Torralba
- Nanobioelectronics & Biosensors Group, Institut Català de Nanociència I Nanotecnologia (ICN2), CSIC and the Barcelona Institute of Science and Technology (BIST), Campus UAB, 08193, Bellaterra, Barcelona, Spain
| | - Duy Ba Ngo
- School of Bioresources and Technology, King Mongkut's University of Technology Thonburi (KMUTT), Bangkok, 10150, Thailand
| | - Claudio Parolo
- Nanobioelectronics & Biosensors Group, Institut Català de Nanociència I Nanotecnologia (ICN2), CSIC and the Barcelona Institute of Science and Technology (BIST), Campus UAB, 08193, Bellaterra, Barcelona, Spain
| | - Liming Hu
- Nanobioelectronics & Biosensors Group, Institut Català de Nanociència I Nanotecnologia (ICN2), CSIC and the Barcelona Institute of Science and Technology (BIST), Campus UAB, 08193, Bellaterra, Barcelona, Spain
| | - Ruslan Álvarez-Diduk
- Nanobioelectronics & Biosensors Group, Institut Català de Nanociència I Nanotecnologia (ICN2), CSIC and the Barcelona Institute of Science and Technology (BIST), Campus UAB, 08193, Bellaterra, Barcelona, Spain
| | - José Francisco Bergua
- Nanobioelectronics & Biosensors Group, Institut Català de Nanociència I Nanotecnologia (ICN2), CSIC and the Barcelona Institute of Science and Technology (BIST), Campus UAB, 08193, Bellaterra, Barcelona, Spain
| | - Giulio Rosati
- Nanobioelectronics & Biosensors Group, Institut Català de Nanociència I Nanotecnologia (ICN2), CSIC and the Barcelona Institute of Science and Technology (BIST), Campus UAB, 08193, Bellaterra, Barcelona, Spain
| | - Werasak Surareungchai
- School of Bioresources and Technology, King Mongkut's University of Technology Thonburi (KMUTT), Bangkok, 10150, Thailand; Nanoscience and Nanotechnology Graduate Research Program, Faculty of Science, KMUTT, Bangkok, 10140, Thailand
| | - Arben Merkoçi
- Nanobioelectronics & Biosensors Group, Institut Català de Nanociència I Nanotecnologia (ICN2), CSIC and the Barcelona Institute of Science and Technology (BIST), Campus UAB, 08193, Bellaterra, Barcelona, Spain; Catalan Institution for Research and Advanced Studies (ICREA), Pg. Lluís Company 23, 08010, Barcelona, Spain.
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18
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Jayanthi S, Lupulescu A. Sensitivity enhancement in 2D Double Cross Polarization experiments under fast MAS by recycling unused protons. Solid State Nucl Magn Reson 2020; 107:101652. [PMID: 32155567 DOI: 10.1016/j.ssnmr.2020.101652] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 02/09/2020] [Accepted: 02/10/2020] [Indexed: 06/10/2023]
Abstract
We demonstrate sensitivity enhancement via recycling of proton magnetization in 2D Double Cross Polarization (Double CP) experiments performed on fully protonated and uniformly labeled (13C, 15N) samples at a magic angle spinning rate of 60 kHz. Unused proton magnetization is preserved during t1 evolution either by locking it with CW irradiation or by employing rotor-synchronized pi pulses. A flip-back pulse together with a modified second CP block preserves unused proton magnetization resulting in enhanced sensitivity. We have achieved sensitivity enhancements of 15-20% and 25-28% in 1H-13C and 1H-15N 2D Double CP experiments respectively. At shorter recycle delays (∼0.25T1), relative sensitivity enhancements of 40-45% and 55% were obtained in 1H-13C and 1H-15N 2D Double CP experiments respectively. An analysis of the sensitivity enhancements and theoretical estimation of lineshapes in indirect dimension in the presence of proton recycling is provided.
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Affiliation(s)
- Sundaresan Jayanthi
- Department of Physics, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram, 695 547, Kerala, India
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19
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Meikle TG, Sethi A, Keizer DW, Babon JJ, Separovic F, Gooley PR, Conn CE, Yao S. Heteronuclear NMR spectroscopy of proteins encapsulated in cubic phase lipids. J Magn Reson 2019; 305:146-151. [PMID: 31284168 DOI: 10.1016/j.jmr.2019.06.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 06/24/2019] [Accepted: 06/29/2019] [Indexed: 06/09/2023]
Abstract
Lipidic cubic phases, which form spontaneously via the self-assembly of certain lipids in an aqueous environment, are highly prospective nanomaterials with applications in membrane protein X-ray crystallography and drug delivery. Here we report 1H-15N heteronuclear single/multiple quantum coherence (HSQC, HMQC) spectra of 15N-enriched proteins encapsulated in inverse bicontinuous lipidic cubic phases obtained on a standard commercial high resolution NMR spectrometer at ambient temperature. 15N-enriched proteins encapsulated in this lipidic cubic phase show: (i) no significant changes in tertiary structure, (ii) significantly reduced solvent chemical exchange of backbone amides, which potentially provides a novel concept for quantifying residue-specific hydration; and (iii) improved spectral sensitivity achieved with band-selective excitation short-transient (BEST) spectroscopy, which is attributed to the presence of an abundant source of 1H nuclear spins originating from the lipid component of the cubic phase.
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Affiliation(s)
- Thomas G Meikle
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC 3000, Australia
| | - Ashish Sethi
- Department of Biochemistry & Molecular Biology, The University of Melbourne, VIC 3010, Australia; Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia
| | - David W Keizer
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia
| | - Jeffrey J Babon
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, The University of Melbourne, VIC 3010, Australia
| | - Frances Separovic
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia; School of Chemistry, The University of Melbourne, VIC 3010, Australia
| | - Paul R Gooley
- Department of Biochemistry & Molecular Biology, The University of Melbourne, VIC 3010, Australia; Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia
| | - Charlotte E Conn
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC 3000, Australia
| | - Shenggen Yao
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia.
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20
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Patil PO, Pandey GR, Patil AG, Borse VB, Deshmukh PK, Patil DR, Tade RS, Nangare SN, Khan ZG, Patil AM, More MP, Veerapandian M, Bari SB. Graphene-based nanocomposites for sensitivity enhancement of surface plasmon resonance sensor for biological and chemical sensing: A review. Biosens Bioelectron 2019; 139:111324. [PMID: 31121435 DOI: 10.1016/j.bios.2019.111324] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 05/01/2019] [Accepted: 05/12/2019] [Indexed: 02/07/2023]
Abstract
Surface plasmon resonance (SPR) offers exceptional advantages such as label-free, in-situ and real-time measurement ability that facilitates the study of molecular or chemical binding events. Besides, SPR lacks in the detection of various binding events, particularly involving low molecular weight molecules. This drawback ultimately resulted in the development of several sensitivity enhancement methodologies and their application in the various area. Among graphene materials, graphene-based nanocomposites stands out owing to its significant properties such as strong adsorption of molecules, signal amplification by optical, high carrier mobility, electronic bridging, ease of fabrication and therefore, have established as an important sensitivity enhancement substrate for SPR. Also, graphene-based nanocomposites could amplify the signal generated by plasmon material and increase the sensitivity of molecular detection up to femto to atto molar level. This review focuses on the current important developments made in the potential research avenue of SPR and fiber optics based SPR for chemical and biological sensing. Latest trends and challenges in engineering and applications of graphene-based nanocomposites enhanced sensors for detecting minute and low concentration biological and chemical analytes are reviewed comprehensively. This review may aid in futuristic designing approaches and application of grapheneous sensor platforms for sensitive plasmonic nano-sensors.
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Affiliation(s)
- Pravin O Patil
- H. R. Patel Institute of Pharmaceutical Education and Research, Shirpur, 425405, Maharashtra, India.
| | - Gaurav R Pandey
- H. R. Patel Institute of Pharmaceutical Education and Research, Shirpur, 425405, Maharashtra, India
| | - Ashwini G Patil
- R. C. Patel Arts, Science and Commerce College, Shirpur, 425405, Maharashtra, India
| | - Vivek B Borse
- Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Prashant K Deshmukh
- H. R. Patel Institute of Pharmaceutical Education and Research, Shirpur, 425405, Maharashtra, India
| | - Dilip R Patil
- R. C. Patel Arts, Science and Commerce College, Shirpur, 425405, Maharashtra, India
| | - Rahul S Tade
- H. R. Patel Institute of Pharmaceutical Education and Research, Shirpur, 425405, Maharashtra, India
| | - Sopan N Nangare
- H. R. Patel Institute of Pharmaceutical Education and Research, Shirpur, 425405, Maharashtra, India
| | - Zamir G Khan
- H. R. Patel Institute of Pharmaceutical Education and Research, Shirpur, 425405, Maharashtra, India
| | - Arun M Patil
- R. C. Patel Arts, Science and Commerce College, Shirpur, 425405, Maharashtra, India
| | - Mahesh P More
- H. R. Patel Institute of Pharmaceutical Education and Research, Shirpur, 425405, Maharashtra, India
| | - Murugan Veerapandian
- Council of Scientific and Industrial Research-Central Electrochemical Research Institute, Karaikudi-630003, Tamilnadu, India
| | - Sanjay B Bari
- H. R. Patel Institute of Pharmaceutical Education and Research, Shirpur, 425405, Maharashtra, India
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21
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Yesinowski JP, Miller JB, Klug CA, Ricks-Laskoski HL. Optorelaxers: Achieving real-time control of NMR relaxation. Solid State Nucl Magn Reson 2018; 96:1-9. [PMID: 30253250 DOI: 10.1016/j.ssnmr.2018.09.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 08/29/2018] [Accepted: 09/05/2018] [Indexed: 06/08/2023]
Abstract
We present an approach to increase the detection sensitivity of NMR by shortening the spin-lattice relaxation time using transient paramagnetic species created by light irradiation of "optorelaxer" molecules. In the ultimate implementation of this concept, not yet realized here, these transient species are absent during the detection period, thereby avoiding the loss of spectral resolution caused by inhomogeneous broadening from paramagnetic species. Real-time control of NMR relaxation by visible light is demonstrated with Fe(II)(ptz)6(BF4)2, (ptz = 1-propyltetrazole), abbreviated FePTZ. Illumination of FePTZ at 30 K results in a decrease of the 1H NMR spin-lattice relaxation time T1 due to formation of a high spin photoexcited state. The 1H NMR of polystyrene containing a low concentration of FePTZ molecules shows a similar reduction in T1, establishing that FePTZ can act as an optorelaxer for the protons of a matrix. Numerical modeling of the spin-diffusion processes from the protons in a FePTZ core to those in a shell of polystyrene accounts for the observed T1 effects under both dark and light conditions. Additionally, 1H MAS (magic-angle spinning) NMR results for pure FePTZ provide information on the isotropic and anisotropic portions of the electron-nuclear hyperfine interactions.
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Affiliation(s)
| | - Joel B Miller
- Naval Research Laboratory, Washington, DC, 20375, USA
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22
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Novakovic M, Cousin SF, Jaroszewicz MJ, Rosenzweig R, Frydman L. Looped-PROjected SpectroscopY (L-PROSY): A simple approach to enhance backbone/sidechain cross-peaks in 1H NMR. J Magn Reson 2018; 294:169-180. [PMID: 30064051 DOI: 10.1016/j.jmr.2018.07.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 07/10/2018] [Accepted: 07/13/2018] [Indexed: 05/08/2023]
Abstract
Cross-relaxation and isotropic mixing phenomena leading to the Nuclear Overhauser Effect (NOE) and to the TOCSY experiment, lie at the center of structural determinations by NMR. 2D TOCSY and NOESY exploit these polarization transfer effects to determine inter-site connectivities and molecular geometries under physiologically-relevant conditions. Among these sequences' drawback, particularly for the case of NOEs, are a lack of sensitivity arising from small structurally-relevant cross peaks. The present study explores the application of multiple Zeno-like projective measurements, to enhance the cross-peaks between spectrally distinct groups in proteins -in particular between amide and aliphatic protons. The enhancement is based on repeating the projection done by Ramsey or TOCSY blocks multiple times, in what we refer to as Looped, PROjected Spectroscopy (L-PROSY). This leads to a reset of the amide/aliphatic transfer processes; the initial slopes of the NOE- or J-transfer effects thus define the cross-peak growth, and a faster cross-peak buildup is achieved upon looping these transfers over the allotted time T1. These projections also help to better preserve the magnetization originating in the amides, resulting in an overall improvement in sensitivity. L-PROSY's usefulness is demonstrated by incorporating it into two widely used protein NMR experiments: 2D 15N-1H HMQC-NOESY and 15N-filtered 2D NOESY. Different parameters dictating the overall SNR improvement, particularly the protein correlation times and the amide-water chemical exchange rates, were examined, and L-PROSY's enhancements resulted for all tested proteins. The largest cross-peak enhancements were observed for unstructured proteins, where chemical exchanges with the solvent of the kind that tend to average out NOE cross-peaks in conventional NMR, boost L-PROSY's cross-peaks by replenishing the amide's magnetizations within each loop. Enhanced cross-peaks were also found in extensions involving TOCSY-based experiments when applied to proteins with unfolded segments.
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Affiliation(s)
- Mihajlo Novakovic
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Samuel F Cousin
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Michael J Jaroszewicz
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Rina Rosenzweig
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Lucio Frydman
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
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23
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Fu R, Hernández-Maldonado AJ. Boosting sensitivity and suppressing artifacts via multi-acquisition in direct polarization NMR experiments with small flip-angle pulses. J Magn Reson 2018; 293:34-40. [PMID: 29890484 DOI: 10.1016/j.jmr.2018.05.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 05/19/2018] [Accepted: 05/23/2018] [Indexed: 06/08/2023]
Abstract
A small flip-angle pulse direct polarization is the simplest method commonly used to quantify various compositions in many materials applications. This method sacrifices the sensitivity per scan in exchange for rapid repeating of data acquisition for signal accumulation. In addition, the resulting spectrum often encounters artifacts from background signals from probe components and/or from acoustic rings leading to a distorted baseline, especially in low-γ nuclei and wideline NMR. In this work, a multi-acquisition scheme is proposed to boost the sensitivity per scan and at the same time effectively suppress these artifacts. Here, an adiabatic inversion pulse is first applied in order to bring the magnetization from the +z to -z axis and then a small flip-angle pulse excitation is used before the data acquisition. Right after the first acquisition, the adiabatic inversion pulse is applied again to flip the magnetization back to the +z axis. The second data acquisition takes place after another small flip-angle pulse excitation. The difference between the two consecutive acquisitions cancels out any artifacts, while the wanted signals are accumulated. This acquisition process can be repeated many times before going into next scan. Therefore, by acquiring the signals multiple times in a single scan the sensitivity is improved. A mixture sample of flufenamic acid and 3,5-difluorobenzoic acid and a titanium silicate sample have been used to demonstrate the advantages of this newly proposed method.
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Affiliation(s)
- Riqiang Fu
- National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, United States.
| | - Arturo J Hernández-Maldonado
- Department of Chemical Engineering, University of Puerto Rico-Mayagüez Campus, Mayagüez, PR 00681-9000, United States
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Meier T, Khandarkhaeva S, Petitgirard S, Körber T, Lauerer A, Rössler E, Dubrovinsky L. NMR at pressures up to 90 GPa. J Magn Reson 2018; 292:44-47. [PMID: 29778072 DOI: 10.1016/j.jmr.2018.05.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 05/02/2018] [Accepted: 05/04/2018] [Indexed: 06/08/2023]
Abstract
The past 15 years have seen an astonishing increase in Nuclear Magnetic Resonance (NMR) sensitivity and accessible pressure range in high-pressure NMR experiments, owing to a series of new developments of NMR spectroscopy applied to the diamond anvil cell (DAC). Recently, with the application of electro-magnetic lenses, so-called Lenz lenses, in toroidal diamond indenter cells, pressures of up to 72 GPa with NMR spin sensitivities of about 1012 spin/Hz1/2 has been achieved. Here, we describe the implementation of a refined NMR resonator structure using a pair of double stage Lenz lenses driven by a Helmholtz coil within a standard DAC, allowing to measure sample volumes as small as 100 pl prior to compression. With this set-up, pressures close to 100 GPa could be realised repeatedly, with enhanced spin sensitivities of about 5 × 1011 spin/Hz1/2. The manufacturing and handling of these new NMR-DACs is relatively easy and straightforward, which will allow for further applications in physics, chemistry, or biochemistry.
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Affiliation(s)
- Thomas Meier
- Bayerisches Geoinstitut, Bayreuth University, Universitätsstraße 30, 95447 Bayreuth, Germany.
| | - Saiana Khandarkhaeva
- Bayerisches Geoinstitut, Bayreuth University, Universitätsstraße 30, 95447 Bayreuth, Germany
| | - Sylvain Petitgirard
- Bayerisches Geoinstitut, Bayreuth University, Universitätsstraße 30, 95447 Bayreuth, Germany
| | - Thomas Körber
- Fakultät für Mathematik, Physik und Informatik, Experimentalphysik II, Bayreuth University, Universitätsstraße 30, 95447 Bayreuth, Germany
| | - Alexander Lauerer
- Institut für Materialwissenschaften, Hochschule Hof, Alfons-Goppel-Platz 1, 95028 Hof, Germany
| | - Ernst Rössler
- Fakultät für Mathematik, Physik und Informatik, Experimentalphysik II, Bayreuth University, Universitätsstraße 30, 95447 Bayreuth, Germany
| | - Leonid Dubrovinsky
- Bayerisches Geoinstitut, Bayreuth University, Universitätsstraße 30, 95447 Bayreuth, Germany
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25
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Meier T. Journey to the centre of the Earth: Jules Vernes' dream in the laboratory from an NMR perspective. Prog Nucl Magn Reson Spectrosc 2018; 106-107:26-36. [PMID: 31047600 DOI: 10.1016/j.pnmrs.2018.04.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 04/11/2018] [Accepted: 04/12/2018] [Indexed: 06/09/2023]
Abstract
High pressure nuclear magnetic resonance is among the most challenging fields of research for NMR spectroscopists due to inherently low signal intensities, ultra-small samples that are barely accessible, and overall extremely harsh conditions in the sample cavity of modern high pressure vessels. This review aims to provide a comprehensive overview of the topic of high pressure research and its fairly young and brief relationship with NMR.
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Affiliation(s)
- Thomas Meier
- Bayerisches Geoinstitut, Universitt Bayreuth, Universittsstrae 30, D-95447 Bayreuth, Germany.
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26
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Leninger M, Marsiglia WM, Jerschow A, Traaseth NJ. Multiple frequency saturation pulses reduce CEST acquisition time for quantifying conformational exchange in biomolecules. J Biomol NMR 2018; 71:19-30. [PMID: 29796789 PMCID: PMC5989009 DOI: 10.1007/s10858-018-0186-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 05/11/2018] [Indexed: 05/03/2023]
Abstract
Exchange between conformational states is required for biomolecular catalysis, allostery, and folding. A variety of NMR experiments have been developed to quantify motional regimes ranging from nanoseconds to seconds. In this work, we describe an approach to speed up the acquisition of chemical exchange saturation transfer (CEST) experiments that are commonly used to probe millisecond to second conformational exchange in proteins and nucleic acids. The standard approach is to obtain CEST datasets through the acquisition of a series of 2D correlation spectra where each experiment utilizes a single saturation frequency to 1H, 15N or 13C. These pseudo 3D datasets are time consuming to collect and are further lengthened by reduced signal to noise stemming from the long saturation pulse. In this article, we show how usage of a multiple frequency saturation pulse (i.e., MF-CEST) changes the nature of data collection from series to parallel, and thus decreases the total acquisition time by an integer factor corresponding to the number of frequencies in the pulse. We demonstrate the applicability of MF-CEST on a Src homology 2 (SH2) domain from phospholipase Cγ and the secondary active transport protein EmrE as model systems by collecting 13C methyl and 15N backbone datasets. MF-CEST can also be extended to additional sites within proteins and nucleic acids. The only notable drawback of MF-CEST as applied to backbone 15N experiments occurs when a large chemical shift difference between the major and minor populations is present (typically greater than ~ 8 ppm). In these cases, ambiguity may arise between the chemical shift of the minor population and the multiple frequency saturation pulse. Nevertheless, this drawback does not occur for methyl group MF-CEST experiments or in cases where somewhat smaller chemical shift differences occur are present.
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Affiliation(s)
- Maureen Leninger
- Department of Chemistry, New York University, 100 Washington Square East, New York, NY, 10003, USA
| | - William M Marsiglia
- Department of Chemistry, New York University, 100 Washington Square East, New York, NY, 10003, USA
| | - Alexej Jerschow
- Department of Chemistry, New York University, 100 Washington Square East, New York, NY, 10003, USA
| | - Nathaniel J Traaseth
- Department of Chemistry, New York University, 100 Washington Square East, New York, NY, 10003, USA.
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Abstract
Biomolecular solid-state NMR experiments have traditionally been collected through detection of 13C or 15N nuclei. Since these nuclei have relatively low sensitivity stemming from their smaller gyromagnetic ratios relative to 1H, the time required to collect multi-dimensional datasets serves as a limitation to resonance assignment and structure determination. One improvement in the field has been to employ simultaneous or parallel acquisition techniques with the goal of acquiring more than one dataset at a time and therefore speeding up the overall data collection process. Central to these experiments is the cross-polarization (CP) element, which serves as a way to transfer magnetization between nuclei via magnetic dipolar couplings. In this chapter, we show how residual signal remaining after CP is a polarization source that can be used to acquire additional datasets. The setup of this class of experiments, referred to as Afterglow spectroscopy, is described and demonstrated using a membrane protein transporter involved in multidrug resistance.
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Affiliation(s)
- Gili Abramov
- Department of Chemistry, New York University, 100 Washington Square East, New York, NY, 10003, USA
| | - Nathaniel J Traaseth
- Department of Chemistry, New York University, 100 Washington Square East, New York, NY, 10003, USA.
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28
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Wang S, Gopinath T, Veglia G. Application of paramagnetic relaxation enhancements to accelerate the acquisition of 2D and 3D solid-state NMR spectra of oriented membrane proteins. Methods 2017; 138-139:54-61. [PMID: 29274874 DOI: 10.1016/j.ymeth.2017.12.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 12/14/2017] [Accepted: 12/19/2017] [Indexed: 12/21/2022] Open
Abstract
Oriented sample solid-state NMR (OS-ssNMR) spectroscopy is uniquely suited to determine membrane protein topology at the atomic resolution in liquid crystalline bilayers under physiological temperature. However, the inherent low sensitivity of this technique has hindered the throughput of multidimensional experiments necessary for resonance assignments and structure determination. In this work, we show that doping membrane protein bicelle preparations with paramagnetic ion chelated lipids and exploiting paramagnetic relaxation effects it is possible to accelerate the acquisition of both 2D and 3D multidimensional experiments with significant saving in time. We demonstrate the efficacy of this method for a small membrane protein, sarcolipin, reconstituted in DMPC/POPC/DHPC oriented bicelles. In particular, using Cu2+-DMPE-DTPA as a dopant, we observed a decrease of 1H T1 of sarcolipin by 2/3, allowing us to reduce the recycle delay up to 3 times. We anticipate that these new developments will enable the routine acquisition of multidimensional OS-ssNMR experiments.
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Affiliation(s)
- Songlin Wang
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
| | - T Gopinath
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States; Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States.
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29
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Xia Y, Rossi P, Subrahmanian MV, Huang C, Saleh T, Olivieri C, Kalodimos CG, Veglia G. Enhancing the sensitivity of multidimensional NMR experiments by using triply-compensated π pulses. J Biomol NMR 2017; 69:237-243. [PMID: 29164453 PMCID: PMC5738291 DOI: 10.1007/s10858-017-0153-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 11/14/2017] [Indexed: 06/04/2023]
Abstract
In multidimensional solution NMR experiments, π pulses are used extensively for inversion and refocusing operations on 1H, 13C and 15N nuclei. Pulse miscalibration, off-resonance effects, and J-coupling evolution during π pulse execution result in severe signal losses that are exacerbated at high magnetic fields. Here, we report the implementation of a triply-compensated π pulse (G5) optimized for both inversion and refocusing in widely used 2- and 3-dimensional experiments. By replacing most of the hard π pulses, adiabatic or composite pulses on the 1H, 13C and 15N channels with G5 pulses, we obtained signal enhancements ranging from 80 to 240%. We anticipate that triply-compensated pulses will be crucial for improving the performance of multidimensional and multinuclear pulse sequences at ultra-high fields.
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Affiliation(s)
- Youlin Xia
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
- Department of Structural Biology, St Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Paolo Rossi
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
- Department of Structural Biology, St Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Manu V Subrahmanian
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Chengdong Huang
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
- Department of Structural Biology, St Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Tamjeed Saleh
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
- Department of Structural Biology, St Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Cristina Olivieri
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Charalampos G Kalodimos
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA.
- Department of Structural Biology, St Jude Children's Research Hospital, Memphis, TN, 38105, USA.
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA.
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30
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Wuethrich A, Quirino JP. Derivatisation for separation and detection in capillary electrophoresis (2015-2017). Electrophoresis 2017; 39:82-96. [PMID: 28758685 DOI: 10.1002/elps.201700252] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 07/25/2017] [Accepted: 07/26/2017] [Indexed: 02/01/2023]
Abstract
Derivatisation is an integrated part of many analytical workflows to enable separation and detection of the analytes. In CE, derivatisation is adapted in the four modes of pre-capillary, in-line, in-capillary, and post-capillary derivatisation. In this review, we discuss the progress in derivatisation from February 2015 to May 2017 from multiple points of view including sections about the derivatisation modes, derivatisation to improve the analyte separation and analyte detection. The advancements in derivatisation procedures, novel reagents, and applications are covered. A table summarising the 46 reviewed articles with information about analyte, sample, derivatisation route, CE method and method sensitivity is provided.
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Affiliation(s)
- Alain Wuethrich
- Centre for Personalised Nanomedicine, Australian Institute for Bioengineering and Nanotechnology (AIBN), University of Queensland, Brisbane, QLD, Australia
| | - Joselito P Quirino
- Australian Centre for Research on Separation Science (ACROSS), School of Physical Sciences-Chemistry, University of Tasmania, Hobart, TAS, Australia
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31
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Petrakova AV, Urusov AE, Gubaydullina MK, Bartosh AV, Zherdev AV, Dzantiev BB. "External" antibodies as the simplest tool for sensitive immunochromatographic tests. Talanta 2017; 175:77-81. [PMID: 28842038 DOI: 10.1016/j.talanta.2017.07.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 07/05/2017] [Accepted: 07/10/2017] [Indexed: 02/07/2023]
Abstract
The scheme of immunochromatographic competitive analysis with "external" specific antibodies is offered for the first time. The test strip includes all the necessary components for analysis (membranes, protein antigen conjugates, colored nanoparticles), except specific free unconjugated antibodies that are transferred to the buffer used for sample dilution. Thus, the concentrations of the antibodies and markers can be chosen independently, and dilution of the sample with buffer (a routine procedure for any immunochromatographic test) ensures pre-incubation of the antibodies with the sample. Both factors increase the sensitivity of the test. The proposed scheme has been proven to be effective for the determination of deoxynivalenol and T-2 toxin; detection limits of 500pg/mL and 50pg/mL, respectively, were achieved. This is an order of magnitude lower than the limits of detection of traditional tests using the same reagents. The analysis was conducted in water-organic extracts (20% methanol); the duration of the analysis is 10min (it's the same time as for a traditional test). The proposed approach is universal, and it can be used to detect a variety of compounds.
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Affiliation(s)
- Alina V Petrakova
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospect 33, 119071 Moscow, Russia
| | - Alexandr E Urusov
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospect 33, 119071 Moscow, Russia
| | - Milyausha K Gubaydullina
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospect 33, 119071 Moscow, Russia
| | - Anastasia V Bartosh
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospect 33, 119071 Moscow, Russia
| | - Anatoly V Zherdev
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospect 33, 119071 Moscow, Russia
| | - Boris B Dzantiev
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospect 33, 119071 Moscow, Russia.
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32
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Tokunaga T, Akagi KI, Okamoto M. Sensitivity enhancement by chromatographic peak concentration with ultra-high performance liquid chromatography-nuclear magnetic resonance spectroscopy for minor impurity analysis. J Chromatogr A 2017; 1508:163-8. [PMID: 28619585 DOI: 10.1016/j.chroma.2017.06.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 04/14/2017] [Accepted: 06/07/2017] [Indexed: 01/02/2023]
Abstract
High performance liquid chromatography can be coupled with nuclear magnetic resonance (NMR) spectroscopy to give a powerful analytical method known as liquid chromatography-nuclear magnetic resonance (LC-NMR) spectroscopy, which can be used to determine the chemical structures of the components of complex mixtures. However, intrinsic limitations in the sensitivity of NMR spectroscopy have restricted the scope of this procedure, and resolving these limitations remains a critical problem for analysis. In this study, we coupled ultra-high performance liquid chromatography (UHPLC) with NMR to give a simple and versatile analytical method with higher sensitivity than conventional LC-NMR. UHPLC separation enabled the concentration of individual peaks to give a volume similar to that of the NMR flow cell, thereby maximizing the sensitivity to the theoretical upper limit. The UHPLC concentration of compound peaks present at typical impurity levels (5.0-13.1 nmol) in a mixture led to at most three-fold increase in the signal-to-noise ratio compared with LC-NMR. Furthermore, we demonstrated the use of UHPLC-NMR for obtaining structural information of a minor impurity in a reaction mixture in actual laboratory-scale development of a synthetic process. Using UHPLC-NMR, the experimental run times for chromatography and NMR were greatly reduced compared with LC-NMR. UHPLC-NMR successfully overcomes the difficulties associated with analyses of minor components in a complex mixture by LC-NMR, which are problematic even when an ultra-high field magnet and cryogenic probe are used.
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33
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Motion CL, Cassidy SL, Cruickshank PAS, Hunter RI, Bolton DR, El Mkami H, Van Doorslaer S, Lovett JE, Smith GM. The use of composite pulses for improving DEER signal at 94GHz. J Magn Reson 2017; 278:122-133. [PMID: 28402869 DOI: 10.1016/j.jmr.2017.03.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 03/03/2017] [Accepted: 03/31/2017] [Indexed: 06/07/2023]
Abstract
The sensitivity of pulsed electron paramagnetic resonance (EPR) measurements on broad-line paramagnetic centers is often limited by the available excitation bandwidth. One way to increase excitation bandwidth is through the use of chirp or composite pulses. However, performance can be limited by cavity or detection bandwidth, which in commercial systems is typically 100-200MHz. Here we demonstrate in a 94GHz spectrometer, with >800MHz system bandwidth, an increase in signal and modulation depth in a 4-pulse DEER experiment through use of composite rather than rectangular π pulses. We show that this leads to an increase in sensitivity by a factor of 3, in line with theoretical predictions, although gains are more limited in nitroxide-nitroxide DEER measurements.
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Affiliation(s)
- Claire L Motion
- SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom
| | - Scott L Cassidy
- SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom
| | - Paul A S Cruickshank
- SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom
| | - Robert I Hunter
- SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom
| | - David R Bolton
- SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom
| | - Hassane El Mkami
- SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom
| | | | - Janet E Lovett
- SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom
| | - Graham M Smith
- SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom.
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Koroloff SN, Tesch DM, Awosanya EO, Nevzorov AA. Sensitivity enhancement for membrane proteins reconstituted in parallel and perpendicular oriented bicelles obtained by using repetitive cross-polarization and membrane-incorporated free radicals. J Biomol NMR 2017; 67:135-144. [PMID: 28205016 DOI: 10.1007/s10858-017-0090-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 01/19/2017] [Indexed: 06/06/2023]
Abstract
Multidimensional separated local-field and spin-exchange experiments employed by oriented-sample solid-state NMR are essential for structure determination and spectroscopic assignment of membrane proteins reconstituted in macroscopically aligned lipid bilayers. However, these experiments typically require a large number of scans in order to establish interspin correlations. Here we have shown that a combination of optimized repetitive cross polarization (REP-CP) and membrane-embedded free radicals allows one to enhance the signal-to-noise ratio by factors 2.4-3.0 in the case of Pf1 coat protein reconstituted in magnetically aligned bicelles with their normals being either parallel or perpendicular to the main magnetic field. Notably, spectral resolution is not affected at the 2:1 radical-to-protein ratio. Spectroscopic assignment of Pf1 coat protein in the parallel bicelles has been established as an illustration of the method. The proposed methodology will advance applications of oriented-sample NMR technique when applied to samples containing smaller quantities of proteins and three-dimensional experiments.
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Affiliation(s)
- Sophie N Koroloff
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC, 27695-8204, USA
| | - Deanna M Tesch
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC, 27695-8204, USA
- Shaw University, 118 E. South Street, Raleigh, NC, 27601, USA
| | - Emmanuel O Awosanya
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC, 27695-8204, USA
| | - Alexander A Nevzorov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC, 27695-8204, USA.
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Doll A, Qi M, Godt A, Jeschke G. CIDME: Short distances measured with long chirp pulses. J Magn Reson 2016; 273:73-82. [PMID: 27788378 DOI: 10.1016/j.jmr.2016.10.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 10/10/2016] [Accepted: 10/14/2016] [Indexed: 06/06/2023]
Abstract
Frequency-swept pulses have recently been introduced as pump pulses into double electron-electron resonance (DEER) experiments. A limitation of this approach is that the pump pulses need to be short in comparison to dipolar evolution periods. The "chirp-induced dipolar modulation enhancement" (CIDME) pulse sequence introduced in this work circumvents this limitation by means of longitudinal storage during the application of one single or two consecutive pump pulses. The resulting six-pulse sequence is closely related to the five-pulse "relaxation-induced dipolar modulation enhancement" (RIDME) pulse sequence: While dipolar modulation in RIDME is due to stochastic spin flips during longitudinal storage, modulation in CIDME is due to the pump pulse during longitudinal storage. Experimentally, CIDME is examined for Gd-Gd and nitroxide-nitroxide distance determination using a high-power Q-band spectrometer. Since longitudinal storage results in a 50% signal loss, comparisons between DEER using short chirp pump pulses of 64ns duration and CIDME using longer pump pulses are in favor of DEER. While the lower sensitivity restrains the applicability of CIDME for routine distance determination on high-power spectrometers, this result is not to be generalized to spectrometers having lower power and to specialized "non-routine" applications or different types of spin labels. In particular, the advantage of prolonged CIDME pump pulses is demonstrated for experiments at large frequency offset between the pumped and observed spins. At a frequency separation of 1GHz, where broadening due to dipolar pseudo-secular contributions becomes largely suppressed, a Gd-Gd modulation depth larger than 10% is achieved. Moreover, a CIDME experiment at deliberately reduced power underlines the potential of the new technique for spectrometers with lower power, as often encountered at higher microwave frequencies. With longitudinal storage times T below 10μs, however, CIDME appears rather susceptible to artifacts. For nitroxide-nitroxide experiments, these currently inhibit a faithful data analysis. To facilitate further developments, the artifacts are characterized experimentally. In addition, effects that are specific to the high spin of S=7/2 Gd-centers are examined. Herein, population transfer within the observer spin's multiplet due to the pump pulse as well as excitation of dipolar harmonics are discussed.
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Affiliation(s)
- Andrin Doll
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Mian Qi
- Faculty of Chemistry and Center for Molecular Materials, Bielefeld University, Unversitätsstraße 25, 33615 Bielefeld, Germany
| | - Adelheid Godt
- Faculty of Chemistry and Center for Molecular Materials, Bielefeld University, Unversitätsstraße 25, 33615 Bielefeld, Germany
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland.
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36
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Ivanov MY, Nadolinny VA, Bagryanskaya EG, Grishin YA, Fedin MV, Veber SL. Bismuth germanate as a perspective material for dielectric resonators in EPR spectroscopy. J Magn Reson 2016; 271:83-89. [PMID: 27569694 DOI: 10.1016/j.jmr.2016.08.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 08/16/2016] [Accepted: 08/17/2016] [Indexed: 06/06/2023]
Abstract
High purity bismuth germanate (Bi4(GeO4)3, BGO) is proposed and implemented as an alternative material for dielectric EPR resonators. A significant improvement of the absolute sensitivity can be readily achieved by substituting the alumina insert (ring) by BGO-made one in commercially available X-band EPR probeheads. Four BGO dielectric inserts of 2, 3, 4 and 5mm inner diameter (ID) were made for comparison with standard 5mm inner diameter alumina insert. All inserts were introduced into commercial Bruker EPR resonator ER 4118X-MD-5W1, and their performance was investigated. The Q-values of empty resonators, B1 saturation curves and continuous wave EPR spectra of DPPH (2,2-diphenyl-1-picrylhydrazyl) were measured and analyzed in a temperature range 6-300K. BGO-made resonators were found superior in several important aspects. The background signals arising from BGO are much weaker compared to those of alumina at B=0-0.6T and T=6-300K; this is especially useful for measuring weak signals in the half-field region, as well as those near the central field. Moreover, mechanical properties of BGO allow easy fabrication of dielectric bodies having various shapes and sizes; in particular, small BGO resonators (e.g. ID=2 or 3mm) strongly enhance sensitivity for small samples due to increase of the filling factor. All these advantages have been also inspected in the pulse mode, proving that higher B1 fields and better filling factors can be achieved, contributing to the overall enhancement of the performance.
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Affiliation(s)
- Mikhail Y Ivanov
- International Tomography Center, SB RAS, Novosibirsk 630090, Russia; Novosibirsk State University, Novosibirsk 630090, Russia
| | | | - Elena G Bagryanskaya
- Novosibirsk State University, Novosibirsk 630090, Russia; N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, SB RAS, Novosibirsk 630090, Russia
| | - Yuriy A Grishin
- Voevodsky Institute of Chemical Kinetics and Combustion, SB RAS, Novosibirsk 630090, Russia
| | - Matvey V Fedin
- International Tomography Center, SB RAS, Novosibirsk 630090, Russia; Novosibirsk State University, Novosibirsk 630090, Russia
| | - Sergey L Veber
- International Tomography Center, SB RAS, Novosibirsk 630090, Russia; Novosibirsk State University, Novosibirsk 630090, Russia.
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Seginer A, Olsen GL, Frydman L. Acquiring and processing ultrafast biomolecular 2D NMR experiments using a referenced-based correction. J Biomol NMR 2016; 66:141-157. [PMID: 27683189 DOI: 10.1007/s10858-016-0063-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 09/19/2016] [Indexed: 06/06/2023]
Abstract
Thanks to their special spatiotemporal encoding/decoding scheme, ultrafast (UF) NMR sequences can deliver arbitrary 2D spectra following a single excitation. Regardless of their nature, these sequences have in common their tracing of a path in the [Formula: see text]-[Formula: see text] plane, that will deliver the spectrum being sought after a 1D Fourier transformation versus [Formula: see text]. This need to simultaneously digitize two domains, tends to impose bandwidth limitations along all spectral axes. Along the [Formula: see text]/[Formula: see text] dimension this problem is exacerbated by the fact that odd and even time points are not equispaced, and by additional artifacts such as time shifts between time points sampled while under the action of positive and negative decoding gradients. As a result, odd and even [Formula: see text] points are typically Fourier transformed separately, halving the potential spectral width along this dimension. While this halving of the [Formula: see text] span can be overcome by an interlaced Fourier transform, this post-processing is seldom used because of its sensitivity to hardware inaccuracies requiring even finer corrections of the even/odd [Formula: see text] data points. These corrections have so far been done manually, but are challenging to implement when dealing with low signal-to-noise ratio signals like those associated with biomolecular NMR experiments. This study introduces an algorithm for an automatic correction of all even/odd ultrafast NMR inconsistencies, based on the acquisition of a reference scan on the solvent. This algorithm was verified experimentally using an [Formula: see text]-[Formula: see text] UF-HSQC variant on ubiquitin at 600 MHz. Features of this method as well as of the interlaced Fourier transformation in general, are discussed.
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Affiliation(s)
- Amir Seginer
- Department of Chemical Physics, Weizmann Institute of Science, 76100, Rehovot, Israel
| | - Gregory L Olsen
- Department of Chemical Physics, Weizmann Institute of Science, 76100, Rehovot, Israel
| | - Lucio Frydman
- Department of Chemical Physics, Weizmann Institute of Science, 76100, Rehovot, Israel.
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Ashiba H, Sugiyama Y, Wang X, Shirato H, Higo-Moriguchi K, Taniguchi K, Ohki Y, Fujimaki M. Detection of norovirus virus-like particles using a surface plasmon resonance-assisted fluoroimmunosensor optimized for quantum dot fluorescent labels. Biosens Bioelectron 2017; 93:260-6. [PMID: 27597126 DOI: 10.1016/j.bios.2016.08.099] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 08/26/2016] [Accepted: 08/28/2016] [Indexed: 10/21/2022]
Abstract
A highly sensitive biosensor to detect norovirus in environment is desired to prevent the spread of infection. In this study, we investigated a design of surface plasmon resonance (SPR)-assisted fluoroimmunosensor to increase its sensitivity and performed detection of norovirus virus-like particles (VLPs). A quantum dot fluorescent dye was employed because of its large Stokes shift. The sensor design was optimized for the CdSe-ZnS-based quantum dots. The optimal design was applied to a simple SPR-assisted fluoroimmunosensor that uses a sensor chip equipped with a V-shaped trench. Excitation efficiency of the quantum dots, degree of electric field enhancement by SPR, and intensity of autofluorescence of a substrate of the sensor chip were theoretically and experimentally evaluated to maximize the signal-to-noise ratio. As the result, an excitation wavelength of 390nm was selected to excite SPR on an Al film of the sensor chip. The sandwich assay of norovirus VLPs was performed using the designed sensor. Minimum detectable concentration of 0.01ng/mL, which corresponds to 100 virus-like particles included in the detection region of the V-trench, was demonstrated.
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Liao SY, Lee M, Wang T, Sergeyev IV, Hong M. Efficient DNP NMR of membrane proteins: sample preparation protocols, sensitivity, and radical location. J Biomol NMR 2016; 64:223-37. [PMID: 26873390 PMCID: PMC4826309 DOI: 10.1007/s10858-016-0023-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Accepted: 02/07/2016] [Indexed: 05/04/2023]
Abstract
Although dynamic nuclear polarization (DNP) has dramatically enhanced solid-state NMR spectral sensitivities of many synthetic materials and some biological macromolecules, recent studies of membrane-protein DNP using exogenously doped paramagnetic radicals as polarizing agents have reported varied and sometimes surprisingly limited enhancement factors. This motivated us to carry out a systematic evaluation of sample preparation protocols for optimizing the sensitivity of DNP NMR spectra of membrane-bound peptides and proteins at cryogenic temperatures of ~110 K. We show that mixing the radical with the membrane by direct titration instead of centrifugation gives a significant boost to DNP enhancement. We quantify the relative sensitivity enhancement between AMUPol and TOTAPOL, two commonly used radicals, and between deuterated and protonated lipid membranes. AMUPol shows ~fourfold higher sensitivity enhancement than TOTAPOL, while deuterated lipid membrane does not give net higher sensitivity for the membrane peptides than protonated membrane. Overall, a ~100 fold enhancement between the microwave-on and microwave-off spectra can be achieved on lipid-rich membranes containing conformationally disordered peptides, and absolute sensitivity gains of 105-160 can be obtained between low-temperature DNP spectra and high-temperature non-DNP spectra. We also measured the paramagnetic relaxation enhancement of lipid signals by TOTAPOL and AMUPol, to determine the depths of these two radicals in the lipid bilayer. Our data indicate a bimodal distribution of both radicals, a surface-bound fraction and a membrane-bound fraction where the nitroxides lie at ~10 Å from the membrane surface. TOTAPOL appears to have a higher membrane-embedded fraction than AMUPol. These results should be useful for membrane-protein solid-state NMR studies under DNP conditions and provide insights into how biradicals interact with phospholipid membranes.
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Affiliation(s)
- Shu Y Liao
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Myungwoon Lee
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Tuo Wang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | | | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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Rennella E, Huang R, Velyvis A, Kay LE. (13)CHD2-CEST NMR spectroscopy provides an avenue for studies of conformational exchange in high molecular weight proteins. J Biomol NMR 2015; 63:187-99. [PMID: 26271302 DOI: 10.1007/s10858-015-9974-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 07/31/2015] [Indexed: 05/25/2023]
Abstract
An NMR experiment for quantifying slow (millisecond) time-scale exchange processes involving the interconversion between visible ground state and invisible, conformationally excited state conformers is presented. The approach exploits chemical exchange saturation transfer (CEST) and makes use of (13)CHD2 methyl group probes that can be readily incorporated into otherwise highly deuterated proteins. The methodology is validated with an application to a G48A Fyn SH3 domain that exchanges between a folded conformation and a sparsely populated and transiently formed unfolded ensemble. Experiments on a number of different protein systems, including a 360 kDa half-proteasome, establish that the sensitivity of this (13)CHD2 (13)C-CEST technique can be upwards of a factor of 5 times higher than for a previously published (13)CH3 (13)C-CEST approach (Bouvignies and Kay in J Biomol NMR 53:303-310, 2012), suggesting that the methodology will be powerful for studies of conformational exchange in high molecular weight proteins.
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Affiliation(s)
- Enrico Rennella
- Departments of Molecular Genetics, Biochemistry and Chemistry, The University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Rui Huang
- Departments of Molecular Genetics, Biochemistry and Chemistry, The University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Algirdas Velyvis
- Departments of Molecular Genetics, Biochemistry and Chemistry, The University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Lewis E Kay
- Departments of Molecular Genetics, Biochemistry and Chemistry, The University of Toronto, Toronto, ON, M5S 1A8, Canada.
- Program in Molecular Structure and Function, Hospital for Sick Children, 555 University Avenue, Toronto, ON, M5G 1X8, Canada.
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Doll A, Qi M, Wili N, Pribitzer S, Godt A, Jeschke G. Gd(III)-Gd(III) distance measurements with chirp pump pulses. J Magn Reson 2015; 259:153-62. [PMID: 26340436 DOI: 10.1016/j.jmr.2015.08.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 08/13/2015] [Accepted: 08/14/2015] [Indexed: 05/15/2023]
Abstract
The broad EPR spectrum of Gd(III) spin labels restricts the dipolar modulation depth in distance measurements between Gd(III) pairs to a few percent. To overcome this limitation, frequency-swept chirp pulses are utilized as pump pulses in the DEER experiment. Using a model system with 3.4 nm Gd-Gd distance, application of one single chirp pump pulse at Q-band frequencies leads to modulation depths beyond 10%. However, the larger modulation depth is counteracted by a reduction of the absolute echo intensity due to the pump pulse. As supported by spin dynamics simulations, this effect is primarily driven by signal loss to double-quantum coherence and specific to the Gd(III) high spin state of S=7/2. In order to balance modulation depth and echo intensity for optimum sensitivity, a simple experimental procedure is proposed. An additional improvement by 25% in DEER sensitivity is achieved with two consecutive chirp pump pulses. These pulses pump the Gd(III) spectrum symmetrically around the observation position, therefore mutually compensating for dynamical Bloch-Siegert phase shifts at the observer spins. The improved sensitivity of the DEER data with modulation depths on the order of 20% is due to mitigation of the echo reduction effects by the consecutive pump pulses. In particular, the second pump pulse does not lead to additional signal loss if perfect inversion is assumed. Moreover, the compensation of the dynamical Bloch-Siegert phase prevents signal loss due to spatial dependence of the dynamical phase, which is caused by inhomogeneities in the driving field. The new methodology is combined with pre-polarization techniques to measure long distances up to 8.6 nm, where signal intensity and modulation depth become attenuated by long dipolar evolution windows. In addition, the influence of the zero-field splitting parameters on the echo intensity is studied with simulations. Herein, larger sensitivity is anticipated for Gd(III) complexes with zero-field splitting that is smaller than for the employed Gd-PyMTA complex.
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Affiliation(s)
- Andrin Doll
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Mian Qi
- Faculty of Chemistry and Center for Molecular Materials, Bielefeld University, Unversitätsstraße 25, 33615 Bielefeld, Germany
| | - Nino Wili
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Stephan Pribitzer
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Adelheid Godt
- Faculty of Chemistry and Center for Molecular Materials, Bielefeld University, Unversitätsstraße 25, 33615 Bielefeld, Germany
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland.
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Matsuki Y, Nakamura S, Fukui S, Suematsu H, Fujiwara T. Closed-cycle cold helium magic-angle spinning for sensitivity-enhanced multi-dimensional solid-state NMR. J Magn Reson 2015; 259:76-81. [PMID: 26302269 DOI: 10.1016/j.jmr.2015.08.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 08/04/2015] [Indexed: 05/21/2023]
Abstract
Magic-angle spinning (MAS) NMR is a powerful tool for studying molecular structure and dynamics, but suffers from its low sensitivity. Here, we developed a novel helium-cooling MAS NMR probe system adopting a closed-loop gas recirculation mechanism. In addition to the sensitivity gain due to low temperature, the present system has enabled highly stable MAS (vR=4-12 kHz) at cryogenic temperatures (T=35-120 K) for over a week without consuming helium at a cost for electricity of 16 kW/h. High-resolution 1D and 2D data were recorded for a crystalline tri-peptide sample at T=40 K and B0=16.4 T, where an order of magnitude of sensitivity gain was demonstrated versus room temperature measurement. The low-cost and long-term stable MAS strongly promotes broader application of the brute-force sensitivity-enhanced multi-dimensional MAS NMR, as well as dynamic nuclear polarization (DNP)-enhanced NMR in a temperature range lower than 100 K.
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Affiliation(s)
- Yoh Matsuki
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Shinji Nakamura
- JEOL RESONANCE Inc., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
| | - Shigeo Fukui
- Cryovac Corporation, 2-12-14 Chibune, Nishi Yodogawa, Osaka 555-0013, Japan
| | - Hiroto Suematsu
- JEOL RESONANCE Inc., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
| | - Toshimichi Fujiwara
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
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Koroloff SN, Nevzorov AA. Optimization of cross-polarization at low radiofrequency fields for sensitivity enhancement in solid-state NMR of membrane proteins reconstituted in magnetically aligned bicelles. J Magn Reson 2015; 256:14-22. [PMID: 25965279 DOI: 10.1016/j.jmr.2015.03.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 03/10/2015] [Accepted: 03/15/2015] [Indexed: 06/04/2023]
Abstract
Solid-state NMR (ssNMR) of oriented membrane proteins (MPs) is capable of providing structural and dynamic information at nearly physiological conditions. However, NMR experiments performed on oriented membrane proteins generally suffer from low sensitivity. Moreover, utilization of high-power radiofrequency (RF) irradiations for magnetization transfer may give rise to sample heating, thereby decreasing the efficiency of conventional cross-polarization schemes. Here we have optimized the recently developed repetitive cross-polarization (REP-CP) sequence (Tang et al., 2011) to further increase the magnetization transfer efficiency for membrane proteins reconstituted in magnetically aligned bicelles and compared its performance to single-contact Hartmann-Hahn cross-polarization (CP), CP-MOIST and the adiabatic transfer. It has been found that employing the REP-CP sequence at RF amplitudes of 19kHz instead of the commonly used higher RF fields (>45kHz) enhances the efficiency of REP-CP. An additional 30% signal can be obtained as compared to the previously published REP-CP, and 20% when compared to the re-optimized REP-CP at 50kHz RF fields. Moreover, the (15)N signal gain of low-power REP-CP was found to be 40% over the adiabatic CP and up to 80% over CP-MOIST. Thus, the low-power REP-CP sequence surpasses all of the previous CP schemes in addition of having the tremendous advantage of reducing the RF powers by a factor of seven, thereby preserving the liquid-like bicelle sample. By contrast, in purely static (NAL crystal) and semi-rigid systems (Pf1 phage), the adiabatic CP was found to be more effective. Periodic oscillations of the intensity profile (distinct from the transient oscillations) as a function of the CP contact time and B1 RF field strengths were observed during the REP-CP optimization with the oscillations becoming more pronounced with lower RF fields. Many-spin simulations were performed to explain the oscillations and their periodicity.
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Affiliation(s)
- Sophie N Koroloff
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695-8204, USA
| | - Alexander A Nevzorov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695-8204, USA.
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44
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March C, García JV, Sánchez Á, Arnau A, Jiménez Y, García P, Manclús JJ, Montoya Á. High-frequency phase shift measurement greatly enhances the sensitivity of QCM immunosensors. Biosens Bioelectron 2014; 65:1-8. [PMID: 25461131 DOI: 10.1016/j.bios.2014.10.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 09/10/2014] [Accepted: 10/01/2014] [Indexed: 10/24/2022]
Abstract
In spite of being widely used for in liquid biosensing applications, sensitivity improvement of conventional (5-20MHz) quartz crystal microbalance (QCM) sensors remains an unsolved challenging task. With the help of a new electronic characterization approach based on phase change measurements at a constant fixed frequency, a highly sensitive and versatile high fundamental frequency (HFF) QCM immunosensor has successfully been developed and tested for its use in pesticide (carbaryl and thiabendazole) analysis. The analytical performance of several immunosensors was compared in competitive immunoassays taking carbaryl insecticide as the model analyte. The highest sensitivity was exhibited by the 100MHz HFF-QCM carbaryl immunosensor. When results were compared with those reported for 9MHz QCM, analytical parameters clearly showed an improvement of one order of magnitude for sensitivity (estimated as the I50 value) and two orders of magnitude for the limit of detection (LOD): 30μgl(-1) vs 0.66μgL(-1)I50 value and 11μgL(-1) vs 0.14μgL(-1) LOD, for 9 and 100MHz, respectively. For the fungicide thiabendazole, I50 value was roughly the same as that previously reported for SPR under the same biochemical conditions, whereas LOD improved by a factor of 2. The analytical performance achieved by high frequency QCM immunosensors surpassed those of conventional QCM and SPR, closely approaching the most sensitive ELISAs. The developed 100MHz QCM immunosensor strongly improves sensitivity in biosensing, and therefore can be considered as a very promising new analytical tool for in liquid applications where highly sensitive detection is required.
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Affiliation(s)
- Carmen March
- Instituto Interuniversitario de Investigación en Bioingeniería y Tecnología Orientada al Ser Humano (I3BH), Universitat Politècnica de València, Camino de Vera s/n, Edificio 8B-N, 46022 Valencia, Spain; Advanced Wave Sensors S.L. Valencia, Spain.
| | - José V García
- Advanced Wave Sensors S.L. Valencia, Spain; Grupo de Fenómenos Ondulatorios (GFO), Universitat Politècnica de València, Camino de Vera s/n, Edificio 7F, 46022 Valencia, Spain
| | - Ángel Sánchez
- Instituto Interuniversitario de Investigación en Bioingeniería y Tecnología Orientada al Ser Humano (I3BH), Universitat Politècnica de València, Camino de Vera s/n, Edificio 8B-N, 46022 Valencia, Spain
| | - Antonio Arnau
- Advanced Wave Sensors S.L. Valencia, Spain; Grupo de Fenómenos Ondulatorios (GFO), Universitat Politècnica de València, Camino de Vera s/n, Edificio 7F, 46022 Valencia, Spain
| | - Yolanda Jiménez
- Advanced Wave Sensors S.L. Valencia, Spain; Grupo de Fenómenos Ondulatorios (GFO), Universitat Politècnica de València, Camino de Vera s/n, Edificio 7F, 46022 Valencia, Spain
| | | | - Juan J Manclús
- Instituto Interuniversitario de Investigación en Bioingeniería y Tecnología Orientada al Ser Humano (I3BH), Universitat Politècnica de València, Camino de Vera s/n, Edificio 8B-N, 46022 Valencia, Spain
| | - Ángel Montoya
- Instituto Interuniversitario de Investigación en Bioingeniería y Tecnología Orientada al Ser Humano (I3BH), Universitat Politècnica de València, Camino de Vera s/n, Edificio 8B-N, 46022 Valencia, Spain
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Casabianca LB, Mohr D, Mandal S, Song YQ, Frydman L. Chirped CPMG for well-logging NMR applications. J Magn Reson 2014; 242:197-202. [PMID: 24674888 DOI: 10.1016/j.jmr.2014.02.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2013] [Revised: 02/27/2014] [Accepted: 02/28/2014] [Indexed: 06/03/2023]
Abstract
In NMR well-logging, the measurement apparatus typically consists of a permanent magnet which is inserted into a bore, and the sample is the rock surrounding the borehole. When compared to the conditions of standard NMR experiments, this application is thus challenged by relatively weak and invariably inhomogeneous B0 and B1 fields. Chemical shift information is not generally obtained in these measurements. Instead, diffusivity, porosity and permeability information is collected from multi-echo decay measurements - most often using a Carr-Purcell Meiboom-Gill (CPMG) pulse sequence to enhance the experiment's limited sensitivity. In this work, we explore the consequences of replacing the hard square pulses used in a typical CPMG sequence with chirped pulses sweeping a range of frequencies. The greater bandwidths that for a maximum B1 level can be excited by chirped pulses translates into marked expansion of the detection volume, and thus significant signal-to-noise improvements when compared to standard CPMG acquisitions using hard pulses. This improvement, usually amounting to signal enhancements ⩾3, can be used to reduce the experimental time of NMR well-logging measurements, for measuring T2 even when B0 and B1 inhomogenieties complicate the measurements, and opening new opportunities in the determination of diffusional properties.
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Affiliation(s)
- Leah B Casabianca
- Department of Chemical Physics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Daniel Mohr
- Department of Chemical Physics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Soumyajit Mandal
- Schlumberger-Doll Research, 1 Hampshire Street, Cambridge, MA 02139, United States
| | - Yi-Qiao Song
- Schlumberger-Doll Research, 1 Hampshire Street, Cambridge, MA 02139, United States
| | - Lucio Frydman
- Department of Chemical Physics, The Weizmann Institute of Science, Rehovot 76100, Israel.
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46
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Shen MY, Li BR, Li YK. Silicon nanowire field-effect-transistor based biosensors: from sensitive to ultra-sensitive. Biosens Bioelectron 2014; 60:101-11. [PMID: 24787124 DOI: 10.1016/j.bios.2014.03.057] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Revised: 03/13/2014] [Accepted: 03/23/2014] [Indexed: 02/03/2023]
Abstract
Silicon nanowire field effect transistors (SiNW-FETs) have shown great promise as biosensors in highly sensitive, selective, real-time and label-free measurements. While applications of SiNW-FETs for detection of biological species have been described in several publications, less attention has been devoted to summarize the conjugating methods involved in linking organic bio-receptors with the inorganic transducer and the strategies of improving the sensitivity of devices. This article attempts to focus on summarizing the various organic immobilization approaches and discussing various sensitivity improving strategies, that include (I) reducing non-specific binding, (II) alignment of the probes, (III) enhancing signals by charge reporter, (IV) novel architecture structures, and (V) sensing in the sub-threshold regime.
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Affiliation(s)
- Mo-Yuan Shen
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan
| | - Bor-Ran Li
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan.
| | - Yaw-Kuen Li
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan.
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47
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Gopinath T, Mote KR, Veglia G. Sensitivity and resolution enhancement of oriented solid-state NMR: application to membrane proteins. Prog Nucl Magn Reson Spectrosc 2013; 75:50-68. [PMID: 24160761 PMCID: PMC3850070 DOI: 10.1016/j.pnmrs.2013.07.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 06/16/2013] [Indexed: 05/19/2023]
Abstract
Oriented solid-state NMR (O-ssNMR) spectroscopy is a major technique for the high-resolution analysis of the structure and topology of transmembrane proteins in native-like environments. Unlike magic angle spinning (MAS) techniques, O-ssNMR spectroscopy requires membrane protein preparations that are uniformly oriented (mechanically or magnetically) so that anisotropic NMR parameters, such as dipolar and chemical shift interactions, can be measured to determine structure and orientation of membrane proteins in lipid bilayers. Traditional sample preparations involving mechanically aligned lipids often result in short relaxation times which broaden the (15)N resonances and encumber the manipulation of nuclear spin coherences. The introduction of lipid bicelles as membrane mimicking systems has changed this scenario, and the more favorable relaxation properties of membrane protein (15)N and (13)C resonances make it possible to develop new, more elaborate pulse sequences for higher spectral resolution and sensitivity. Here, we describe our recent progress in the optimization of O-ssNMR pulse sequences. We explain the theory behind these experiments, demonstrate their application to small and medium size proteins, and describe the technical details for setting up these new experiments on the new generation of NMR spectrometers.
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Affiliation(s)
- T. Gopinath
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
| | - Kaustubh R. Mote
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States
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