1
|
Taylor JM, Conboy JC. Sum-frequency vibrational spectroscopy, a tutorial: Applications for the study of lipid membrane structure and dynamics. Biointerphases 2024; 19:031201. [PMID: 38738942 DOI: 10.1116/6.0003594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 04/23/2024] [Indexed: 05/14/2024] Open
Abstract
Planar supported lipid bilayers (PSLBs) are an ideal model for the study of lipid membrane structures and dynamics when using sum-frequency vibrational spectroscopy (SFVS). In this paper, we describe the construction of asymmetric PSLBs and the basic SFVS theory needed to understand and make measurements on these membranes. Several examples are presented, including the determination of phospholipid orientation and measuring phospholipid transmembrane translocation (flip-flop).
Collapse
Affiliation(s)
- Joshua M Taylor
- Department of Chemistry, University of Utah, 315 South 1400 East RM. 2020, Salt Lake City, Utah 84112
| | - John C Conboy
- Department of Chemistry, University of Utah, 315 South 1400 East RM. 2020, Salt Lake City, Utah 84112
| |
Collapse
|
2
|
Sun M, Liu D, Yin G, Li W, Zhou Y, Lu W, Chen Y, Zhang H, Wei F. Magnesium Ion Responses of Zwitterionic Phosphatidylethanolamine Head and Tail Groups Elucidated by Frequency-Resolved SFG-VS. J Phys Chem Lett 2023; 14:2433-2440. [PMID: 36862126 DOI: 10.1021/acs.jpclett.2c03593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
In the present study, the effects of magnesium ions on the conformational changes of the deuterated 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (D54-DMPE) monolayer were elucidated by frequency-resolved sum frequency generation vibrational spectroscopy (SFG-VS) and surface pressure-area isotherm measurements. It is found that the tilt angles of the methyl in tail groups decrease, while the tilt angles of the phosphate and methylene in head groups increase during the compression of the DMPE monolayers at both the air/water interface and the air/MgCl2 solution interfaces. It is also shown that the tilt angle of the methyl in the tail groups slightly decreases, while the tilt angles of the phosphate and methylene in the head groups significantly increase as the MgCl2 concentration increases from 0 to 1.0 M. These results indicate that both the tail groups and the head groups of the DMPE molecules become closer to the surface normal, as the MgCl2 concentration increases in the subphase.
Collapse
Affiliation(s)
- Meng Sun
- School of Optoelectronic Materials and Technology & Institute of Interdisciplinary Research, Jianghan University, Wuhan 430056, China
| | - Dongqi Liu
- School of Optoelectronic Materials and Technology & Institute of Interdisciplinary Research, Jianghan University, Wuhan 430056, China
| | - Guogeng Yin
- School of Optoelectronic Materials and Technology & Institute of Interdisciplinary Research, Jianghan University, Wuhan 430056, China
| | - Wenhui Li
- School of Optoelectronic Materials and Technology & Institute of Interdisciplinary Research, Jianghan University, Wuhan 430056, China
| | - Youhua Zhou
- School of Optoelectronic Materials and Technology & Institute of Interdisciplinary Research, Jianghan University, Wuhan 430056, China
| | - Wangting Lu
- School of Optoelectronic Materials and Technology & Institute of Interdisciplinary Research, Jianghan University, Wuhan 430056, China
| | - Yijie Chen
- College of Food Science and Technology & Key Laboratory of Environment Correlative Dietology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Hongjuan Zhang
- School of Optoelectronic Materials and Technology & Institute of Interdisciplinary Research, Jianghan University, Wuhan 430056, China
| | - Feng Wei
- School of Optoelectronic Materials and Technology & Institute of Interdisciplinary Research, Jianghan University, Wuhan 430056, China
| |
Collapse
|
3
|
He N, Zhao T. Propranolol induces large-scale remodeling of lipid bilayers: tubules, patches, and holes. RSC Adv 2023; 13:7719-7730. [PMID: 36908547 PMCID: PMC9994463 DOI: 10.1039/d3ra00319a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 03/01/2023] [Indexed: 03/11/2023] Open
Abstract
Herein, we report fluorescence microscopy analysis of the interaction between propranolol (PPN), a beta-adrenergic blocking agent, and planar supported lipid bilayers (SLBs), as model membranes. The results indicate that PPN can remarkably promote largescale remodeling in SLBs with various lipid compositions. It was found that PPN insertion induces the formation of long microtubules that can retract into hemispherical caps on the surface of the bilayer. These transformations are dynamic, partially reversible, and dependent upon the drug concentration. Quantitative analysis revealed a three-step model for PPN-lipid bilayer interaction, with the first step involving interfacial electrostatic adsorption, the second step centered on hydrophobic insertion, and the third step associated with membrane disruption and hole formation. By introducing cholesterol, phosphoethanolamine, phosphatidylglycerol, and phosphatidylserine lipids into the phosphocholine SLBs, it was illustrated that both the chemistry of the lipid headgroups and the packing of lipid acyl chains can substantially affect the particular steps in the interactions between PPN and lipid bilayers. Our findings may help to elucidate the possible mechanisms of PPN interaction with lipid membranes, the toxic behavior and overdosage scenarios of beta-blockers, and provide valuable information for drug development and modification.
Collapse
Affiliation(s)
- Ni He
- College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science Shanghai 201620 China +86-021-67791214
| | - Tao Zhao
- College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science Shanghai 201620 China +86-021-67791214
| |
Collapse
|
4
|
Page EF, Blake MJ, Foley GA, Calhoun TR. Monitoring membranes: The exploration of biological bilayers with second harmonic generation. CHEMICAL PHYSICS REVIEWS 2022; 3:041307. [PMID: 36536669 PMCID: PMC9756348 DOI: 10.1063/5.0120888] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 11/03/2022] [Indexed: 12/23/2022]
Abstract
Nature's seemingly controlled chaos in heterogeneous two-dimensional cell membranes stands in stark contrast to the precise, often homogeneous, environment in an experimentalist's flask or carefully designed material system. Yet cell membranes can play a direct role, or serve as inspiration, in all fields of biology, chemistry, physics, and engineering. Our understanding of these ubiquitous structures continues to evolve despite over a century of study largely driven by the application of new technologies. Here, we review the insight afforded by second harmonic generation (SHG), a nonlinear optical technique. From potential measurements to adsorption and diffusion on both model and living systems, SHG complements existing techniques while presenting a large exploratory space for new discoveries.
Collapse
Affiliation(s)
- Eleanor F. Page
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Marea J. Blake
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Grant A. Foley
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Tessa R. Calhoun
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| |
Collapse
|
5
|
Hou Y, Li J, Li B, Yuan Q, Gan W. Combined Second Harmonic Generation and Fluorescence Analyses of the Structures and Dynamics of Molecules on Lipids Using Dual-Probes: A Review. Molecules 2022; 27:molecules27123778. [PMID: 35744902 PMCID: PMC9231091 DOI: 10.3390/molecules27123778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/06/2022] [Accepted: 06/09/2022] [Indexed: 01/25/2023] Open
Abstract
Revealing the structures and dynamic behaviors of molecules on lipids is crucial for understanding the mechanism behind the biophysical processes, such as the preparation and application of drug delivery vesicles. Second harmonic generation (SHG) has been developed as a powerful tool to investigate the molecules on various lipid membranes, benefiting from its natural property of interface selectivity, which comes from the principle of even order nonlinear optics. Fluorescence emission, which is in principle not interface selective but varies with the chemical environment where the chromophores locate, can reveal the dynamics of molecules on lipids. In this contribution, we review some examples, which are mainly from our recent works focusing on the application of combined spectroscopic methods, i.e., SHG and two-photon fluorescence (TPF), in studying the dynamic behaviors of several dyes or drugs on lipids and surfactants. This review demonstrates that molecules with both SHG and TPF efficiencies may be used as intrinsic dual-probes in plotting a clear physical picture of their own behaviors, as well as the dynamics of other molecules, on lipid membranes.
Collapse
Affiliation(s)
- Yi Hou
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, School of Science, Harbin Institute of Technology (Shenzhen), University Town, Shenzhen 518055, China; (Y.H.); (J.L.); (B.L.)
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China
| | - Jianhui Li
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, School of Science, Harbin Institute of Technology (Shenzhen), University Town, Shenzhen 518055, China; (Y.H.); (J.L.); (B.L.)
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China
| | - Bifei Li
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, School of Science, Harbin Institute of Technology (Shenzhen), University Town, Shenzhen 518055, China; (Y.H.); (J.L.); (B.L.)
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China
| | - Qunhui Yuan
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), University Town, Shenzhen 518055, China;
| | - Wei Gan
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, School of Science, Harbin Institute of Technology (Shenzhen), University Town, Shenzhen 518055, China; (Y.H.); (J.L.); (B.L.)
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China
- Correspondence:
| |
Collapse
|
6
|
Schaich M, Cama J, Al Nahas K, Sobota D, Sleath H, Jahnke K, Deshpande S, Dekker C, Keyser UF. An Integrated Microfluidic Platform for Quantifying Drug Permeation across Biomimetic Vesicle Membranes. Mol Pharm 2019; 16:2494-2501. [PMID: 30994358 DOI: 10.1021/acs.molpharmaceut.9b00086] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The low membrane permeability of candidate drug molecules is a major challenge in drug development, and insufficient permeability is one reason for the failure of antibiotic treatment against bacteria. Quantifying drug transport across specific pathways in living systems is challenging because one typically lacks knowledge of the exact lipidome and proteome of the individual cells under investigation. Here, we quantify drug permeability across biomimetic liposome membranes, with comprehensive control over membrane composition. We integrate the microfluidic octanol-assisted liposome assembly platform with an optofluidic transport assay to create a complete microfluidic total analysis system for quantifying drug permeability. Our system enables us to form liposomes with charged lipids mimicking the negative charge of bacterial membranes at physiological pH and salt concentrations, which proved difficult with previous liposome formation techniques. Furthermore, the microfluidic technique yields an order of magnitude more liposomes per experiment than previous assays. We demonstrate the feasibility of the assay by determining the permeability coefficient of norfloxacin and ciprofloxacin across biomimetic liposomes.
Collapse
Affiliation(s)
- Michael Schaich
- Cavendish Laboratory , University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , U.K
| | - Jehangir Cama
- Cavendish Laboratory , University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , U.K.,Living Systems Institute , University of Exeter , Stocker Road , Exeter EX4 4QD , U.K
| | - Kareem Al Nahas
- Cavendish Laboratory , University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , U.K
| | - Diana Sobota
- Cavendish Laboratory , University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , U.K
| | - Hannah Sleath
- Cavendish Laboratory , University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , U.K
| | - Kevin Jahnke
- Cavendish Laboratory , University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , U.K.,Department of Biophysical Chemistry , University of Heidelberg , Im Neuenheimer Feld 253 , D-69120 Heidelberg , Germany.,Department of Cellular Biophysics , Max Planck Institute for Medical Research , Jahnstraße 29 , D-69120 Heidelberg , Germany
| | - Siddharth Deshpande
- Department of Bionanoscience, Kavli Institute of Nanoscience , Delft University of Technology , Van der Maasweg 9 , 2629 HZ Delft , The Netherlands
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience , Delft University of Technology , Van der Maasweg 9 , 2629 HZ Delft , The Netherlands
| | - Ulrich F Keyser
- Cavendish Laboratory , University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , U.K
| |
Collapse
|
7
|
Jimenez CJ, Tan J, Dowell KM, Gadbois GE, Read CA, Burgess N, Cervantes JE, Chan S, Jandaur A, Karanik T, Lee JJ, Ley MC, McGeehan M, McMonigal A, Palazzo KL, Parker SA, Payman A, Soria M, Verheyden L, Vo VT, Yin J, Calkins AL, Fuller AA, Stokes GY. Peptoids advance multidisciplinary research and undergraduate education in parallel: Sequence effects on conformation and lipid interactions. Biopolymers 2019; 110:e23256. [PMID: 30633339 PMCID: PMC6590334 DOI: 10.1002/bip.23256] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 12/17/2018] [Accepted: 12/21/2018] [Indexed: 01/05/2023]
Abstract
Peptoids are versatile peptidomimetic molecules with wide-ranging applications from drug discovery to materials science. An understanding of peptoid sequence features that contribute to both their three-dimensional structures and their interactions with lipids will expand functions of peptoids in varied fields. Furthermore, these topics capture the enthusiasm of undergraduate students who prepare and study diverse peptoids in laboratory coursework and/or in faculty led research. Here, we present the synthesis and study of 21 peptoids with varied functionality, including 19 tripeptoids and 2 longer oligomers. We observed differences in fluorescence spectral features for 10 of the tripeptoids that correlated with peptoid flexibility and relative positioning of chromophores. Interactions of representative peptoids with sonicated glycerophospholipid vesicles were also evaluated using fluorescence spectroscopy. We observed evidence of conformational changes effected by lipids for select peptoids. We also summarize our experiences engaging students in peptoid-based projects to advance both research and undergraduate educational objectives in parallel.
Collapse
Affiliation(s)
- Christian J. Jimenez
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Jiacheng Tan
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Kalli M. Dowell
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Gillian E. Gadbois
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Cameron A. Read
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Nicole Burgess
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Jesus E. Cervantes
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Shannon Chan
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Anmol Jandaur
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Tara Karanik
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Jaenic J. Lee
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Mikaela C. Ley
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Molly McGeehan
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Ann McMonigal
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Kira L. Palazzo
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Samantha A. Parker
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Andre Payman
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Maritza Soria
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Lauren Verheyden
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Vivian T. Vo
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Jennifer Yin
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Anna L. Calkins
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Amelia A. Fuller
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| | - Grace Y. Stokes
- Department of Chemistry & BiochemistrySanta Clara UniversitySanta ClaraCaliforniaU.S.A.
| |
Collapse
|
8
|
Toledo-Fuentes X, Molinaro C, Cecchet F. Interfacial charges drive the organization of supported lipid membranes and their interaction with nanoparticles. Colloids Surf B Biointerfaces 2018; 172:254-261. [DOI: 10.1016/j.colsurfb.2018.08.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 08/10/2018] [Accepted: 08/11/2018] [Indexed: 12/27/2022]
|
9
|
Sun S, Sendecki AM, Pullanchery S, Huang D, Yang T, Cremer PS. Multistep Interactions between Ibuprofen and Lipid Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:10782-10792. [PMID: 30148644 DOI: 10.1021/acs.langmuir.8b01878] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Ibuprofen (IBU) interacts with phosphatidylcholine membranes in three distinct steps as a function of concentration. In a first step (<10 μM), IBU electrostatically adsorbs to the lipid headgroups and gradually decreases the interfacial potential. This first step helps to facilitate the second step (10-300 μM), in which hydrophobic insertion of the drug occurs. The second step disrupts the packing of the lipid acyl chains and expands the area per lipid. In a final step, above 300 μM IBU, the lipid membrane begins to solubilize, resulting in a detergent-like effect. The results described herein were obtained by a combination of fluorescence binding assays, vibrational sum frequency spectroscopy, and Langmuir monolayer compression experiments. By introducing trimethylammonium-propane, phosphatidylglycerol, and phosphatidylethanolamine lipids as well as cholesterol, we demonstrated that both the chemistry of the lipid headgroups and the packing of lipid acyl chains can substantially influence the interactions between IBU and the membranes. Moreover, different membrane chemistries can alter particular steps in the binding interaction.
Collapse
Affiliation(s)
- Simou Sun
- Department of Chemistry , Penn State University , University Park , State College , Pennsylvania 16802 , United States
| | - Anne M Sendecki
- Department of Chemistry , Penn State University , University Park , State College , Pennsylvania 16802 , United States
| | - Saranya Pullanchery
- Department of Chemistry , Penn State University , University Park , State College , Pennsylvania 16802 , United States
| | - Da Huang
- Department of Chemistry , Penn State University , University Park , State College , Pennsylvania 16802 , United States
| | - Tinglu Yang
- Department of Chemistry , Penn State University , University Park , State College , Pennsylvania 16802 , United States
| | - Paul S Cremer
- Department of Chemistry , Penn State University , University Park , State College , Pennsylvania 16802 , United States
- Department of Biochemistry and Molecular Biology , Penn State University , State College , Pennsylvania 16802 , United States
| |
Collapse
|
10
|
Fearon AD, Stokes GY. Thermodynamics of Indomethacin Adsorption to Phospholipid Membranes. J Phys Chem B 2017; 121:10508-10518. [PMID: 29064244 DOI: 10.1021/acs.jpcb.7b08359] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Using second-harmonic generation, we directly monitored adsorption of indomethacin, a nonsteroidal anti-inflammatory drug, to supported lipid bilayers composed of phospholipids of varying phase, cholesterol content, and head group charge without the use of extrinsic labels at therapeutically relevant aqueous concentrations. Indomethacin adsorbed to gel-phase lipids with a high binding affinity, suggesting that like other arylacetic acid-containing drugs, it preferentially interacts with ordered lipid domains. We discovered that adsorption of indomethacin to gel-phase phospholipids was endothermic and entropically driven, whereas adsorption to fluid-phase phospholipids was exothermic and enthalpically driven. As temperature increased from 19 to 34 °C, binding affinities to gel-phase lipids increased by 7-fold but relative surface concentration decreased to one-fifth of the original value. We also compared our results to the entropies reported for indomethacin adsorbed to surfactant micelles, which are used in drug delivery systems, and assert that adsorbed water molecules in the phospholipid bilayer may be buried deeper into the acyl chains and less accessible for disruption. The thermodynamic studies reported here provide mechanistic insight into indomethacin interactions with mammalian plasma membranes in the gastrointestinal tract and inform studies of drug delivery, where indomethacin is commonly used as a prototypical, hydrophobic small-molecule drug.
Collapse
Affiliation(s)
- Amanda D Fearon
- Department of Chemistry and Biochemistry, Santa Clara University , 500 El Camino Real, Santa Clara, California 95053, United States
| | - Grace Y Stokes
- Department of Chemistry and Biochemistry, Santa Clara University , 500 El Camino Real, Santa Clara, California 95053, United States
| |
Collapse
|
11
|
Tran RJ, Sly KL, Conboy JC. Applications of Surface Second Harmonic Generation in Biological Sensing. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2017; 10:387-414. [PMID: 28301745 DOI: 10.1146/annurev-anchem-071015-041453] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Surface second harmonic generation (SHG) is a coherent, nonlinear optical technique that is well suited for investigations of biomolecular interactions at interfaces. SHG is surface specific due to the intrinsic symmetry constraints on the nonlinear process, providing a distinct analytical advantage over linear spectroscopic methods, such as fluorescence and UV-Visible absorbance spectroscopies. SHG has the ability to detect low concentrations of analytes, such as proteins, peptides, and small molecules, due to its high sensitivity, and the second harmonic response can be enhanced through the use of target molecules that are resonant with the incident (ω) and/or second harmonic (2ω) frequencies. This review describes the theoretical background of SHG, and then it discusses its sensitivity, limit of detection, and the implementation of the method. It also encompasses the applications of surface SHG directed at the study of protein-surface, small-molecule-surface, and nanoparticle-membrane interactions, as well as molecular chirality, imaging, and immunoassays. The versatility, high sensitivity, and surface specificity of SHG show great potential for developments in biosensors and bioassays.
Collapse
Affiliation(s)
- Renee J Tran
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112;
| | - Krystal L Sly
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112;
| | - John C Conboy
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112;
| |
Collapse
|
12
|
Silin V, Kasianowicz JJ, Michelman-Ribeiro A, Panchal RG, Bavari S, Robertson JWF. Biochip for the Detection of Bacillus anthracis Lethal Factor and Therapeutic Agents against Anthrax Toxins. MEMBRANES 2016; 6:E36. [PMID: 27348008 PMCID: PMC5041027 DOI: 10.3390/membranes6030036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 06/13/2016] [Accepted: 06/14/2016] [Indexed: 01/18/2023]
Abstract
Tethered lipid bilayer membranes (tBLMs) have been used in many applications, including biosensing and membrane protein structure studies. This report describes a biosensor for anthrax toxins that was fabricated through the self-assembly of a tBLM with B. anthracis protective antigen ion channels that are both the recognition element and electrochemical transducer. We characterize the sensor and its properties with electrochemical impedance spectroscopy and surface plasmon resonance. The sensor shows a sensitivity similar to ELISA and can also be used to rapidly screen for molecules that bind to the toxins and potentially inhibit their lethal effects.
Collapse
Affiliation(s)
- Vitalii Silin
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899-8120, USA.
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-8120, USA.
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20899, USA.
| | - John J Kasianowicz
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899-8120, USA.
| | - Ariel Michelman-Ribeiro
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899-8120, USA.
| | - Rekha G Panchal
- US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD 21702-5011, USA.
| | - Sina Bavari
- US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD 21702-5011, USA.
| | - Joseph W F Robertson
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899-8120, USA.
| |
Collapse
|
13
|
Sly K, Conboy JC. Determination of multivalent protein-ligand binding kinetics by second-harmonic correlation spectroscopy. Anal Chem 2014; 86:11045-54. [PMID: 25314127 PMCID: PMC4238591 DOI: 10.1021/ac500094v] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 10/14/2014] [Indexed: 01/16/2023]
Abstract
Binding kinetics of the multivalent proteins peanut agglutinin (PnA) and cholera toxin B subunit (CTB) to a GM1-doped 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) lipid bilayer were investigated by both second-harmonic correlation spectroscopy (SHCS) and a traditional equilibrium binding isotherm. Adsorption and desorption rates, as well as binding affinity and binding free energy, for three bulk protein concentrations were determined by SHCS. For PnA binding to GM1, the measured adsorption rate decreased with increasing bulk PnA concentration from (3.7 ± 0.3) × 10(6) M(-1)·s(-1) at 0.43 μM PnA to (1.1 ± 0.1) × 10(5) M(-1)·s(-1) at 12 μM PnA. CTB-GM1 exhibited a similar trend, decreasing from (1.0 ± 0.1) × 10(9) M(-1)·s(-1) at 0.5 nM CTB to (3.5 ± 0.2) × 10(6) M(-1)·s(-1) at 240 nM CTB. The measured desorption rates in both studies did not exhibit any dependence on initial protein concentration. As such, 0.43 μM PnA and 0.5 nM CTB had the strongest measured binding affinities, (3.7 ± 0.8) × 10(9) M(-1) and (2.8 ± 0.5) × 10(13) M(-1), respectively. Analysis of the binding isotherm data suggests there is electrostatic repulsion between protein molecules when PnA binds GM1, while CTB-GM1 demonstrates positive ligand-ligand cooperativity. This study provides additional insight into the complex interactions between multivalent proteins and their ligands and showcases SHCS for examining these complex yet technologically important protein-ligand complexes used in biosensors, immunoassays, and other biomedical diagnostics.
Collapse
Affiliation(s)
- Krystal
L. Sly
- Department of
Chemistry, University of Utah, 315 South 1400 East, Room 2020, Salt Lake City, Utah 84112, United States
| | - John C. Conboy
- Department of
Chemistry, University of Utah, 315 South 1400 East, Room 2020, Salt Lake City, Utah 84112, United States
| |
Collapse
|
14
|
Bourgaux C, Couvreur P. Interactions of anticancer drugs with biomembranes: what can we learn from model membranes? J Control Release 2014; 190:127-38. [PMID: 24859379 DOI: 10.1016/j.jconrel.2014.05.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 05/05/2014] [Accepted: 05/07/2014] [Indexed: 10/25/2022]
Abstract
The interactions of anticancer drugs with cell membranes are of primary importance for drug transport, accumulation and activity. However, these interactions are very difficult to investigate because of the complexity of biological membranes. Lipid model membranes have therefore been built to gain insight into the collective role of lipids in drug-membrane interactions. Membranes can act as a barrier for drug molecules, sequester them or conversely may allow them to freely diffuse, thereby modulating the accumulation of drugs into cells. Lipid membranes also affect the ability of the efflux pump Pgp to bind and efflux anticancer drugs from cells. On the other hand, anticancer drugs can alter the structure and properties of lipid membranes, which are expected to influence the functioning of embedded proteins. The relevance of lipid model membranes to assess interactions between anticancer drugs and biomembranes is evidenced.
Collapse
Affiliation(s)
- Claudie Bourgaux
- Institut Galien-Paris Sud, UMR CNRS 8612, Faculté de Pharmacie, Université Paris-Sud, 5 rue J.B. Clément, 92 296 Châtenay-Malabry Cedex, France
| | - Patrick Couvreur
- Institut Galien-Paris Sud, UMR CNRS 8612, Faculté de Pharmacie, Université Paris-Sud, 5 rue J.B. Clément, 92 296 Châtenay-Malabry Cedex, France
| |
Collapse
|
15
|
Huang D, Zhao T, Xu W, Yang T, Cremer PS. Sensing small molecule interactions with lipid membranes by local pH modulation. Anal Chem 2013; 85:10240-8. [PMID: 24152205 DOI: 10.1021/ac401955t] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Herein, we utilized a label-free sensing platform based on pH modulation to detect the interactions between tetracaine, a positively charged small molecule used as a local anesthetic, and planar supported lipid bilayers (SLBs). The SLBs were patterned inside a flow cell, allowing for various concentrations of tetracaine to be introduced over the surface in a buffer solution. Studies with membranes containing POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) yielded an equilibrium dissociation constant value of Kd = 180 ± 47 μm for this small molecule-membrane interaction. Adding cholesterol to the SLBs decreased the affinity between tetracaine and the bilayers, while this interaction tightened when POPE (1-hexadecanoyl-2-(9-Z-octadecenoyl)-sn-glycero-3-phosphoethanolamine) was added. Studies were also conducted with three negatively charged membrane lipids, POPG (1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (sodium salt)), POPS (1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-l-serine (sodium salt)), and ganglioside GM1. All three measurements gave rise to a similar tightening of the apparent Kd value compared with pure POPC membranes. The lack of chemical specificity with the identity of the negatively charged lipid indicated that the tightening was largely electrostatic. Through a direct comparison with ITC measurements, it was found that the pH modulation sensor platform offers a facile, inexpensive, highly sensitive, and rapid method for the detection of interactions between putative drug candidates and lipid bilayers. As such, this technique may potentially be exploited as a screen for drug development and analysis.
Collapse
Affiliation(s)
- Da Huang
- Department of Chemistry and §Department of Biochemistry and Molecular Biology, Penn State University , University Park, PA 16802
| | | | | | | | | |
Collapse
|
16
|
Lis D, Guthmuller J, Champagne B, Humbert C, Busson B, Peremans A, Cecchet F. Vibrational Sum-Frequency Generation Activity of a 2,4-Dinitrophenyl Phospholipid Hybrid Bilayer: Retrieving Orientational Parameters from a DFT Analysis of Experimental Data. Chemphyschem 2013; 14:1227-36. [DOI: 10.1002/cphc.201201063] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Indexed: 12/18/2022]
|
17
|
Prudovsky I, Kumar TKS, Sterling S, Neivandt D. Protein-phospholipid interactions in nonclassical protein secretion: problem and methods of study. Int J Mol Sci 2013; 14:3734-72. [PMID: 23396106 PMCID: PMC3588068 DOI: 10.3390/ijms14023734] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 01/24/2013] [Accepted: 01/25/2013] [Indexed: 12/30/2022] Open
Abstract
Extracellular proteins devoid of signal peptides use nonclassical secretion mechanisms for their export. These mechanisms are independent of the endoplasmic reticulum and Golgi. Some nonclassically released proteins, particularly fibroblast growth factors (FGF) 1 and 2, are exported as a result of their direct translocation through the cell membrane. This process requires specific interactions of released proteins with membrane phospholipids. In this review written by a cell biologist, a structural biologist and two membrane engineers, we discuss the following subjects: (i) Phenomenon of nonclassical protein release and its biological significance; (ii) Composition of the FGF1 multiprotein release complex (MRC); (iii) The relationship between FGF1 export and acidic phospholipid externalization; (iv) Interactions of FGF1 MRC components with acidic phospholipids; (v) Methods to study the transmembrane translocation of proteins; (vi) Membrane models to study nonclassical protein release.
Collapse
Affiliation(s)
- Igor Prudovsky
- Maine Medical Center Research Institute, 81 Research Drive, Scarborough, ME 04074, USA
| | | | - Sarah Sterling
- Department of Chemical and Biological Engineering, University of Maine, Orono, ME 04469, USA; E-Mails: (S.S.); (D.N.)
| | - David Neivandt
- Department of Chemical and Biological Engineering, University of Maine, Orono, ME 04469, USA; E-Mails: (S.S.); (D.N.)
| |
Collapse
|
18
|
Barth C, Jakubczyk D, Kubas A, Anastassacos F, Brenner-Weiss G, Fink K, Schepers U, Bräse S, Koelsch P. Interkingdom signaling: integration, conformation, and orientation of N-acyl-L-homoserine lactones in supported lipid bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:8456-62. [PMID: 22568488 PMCID: PMC3388113 DOI: 10.1021/la301241s] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
N-Acyl-L-homoserine lactones (AHLs) are small cell-to-cell signaling molecules involved in the regulation of population density and local gene expression in microbial communities. Recent evidence shows that contact of this signaling system, usually referred to as quorum sensing, to living eukaryotes results in interactions of AHL with host cells in a process termed "interkingdom signaling". So far details of this process and the binding site of the AHLs remain unknown; both an intracellular and a membrane-bound receptor seem possible, the first of which requires passage through the cell membrane. Here, we used sum-frequency-generation (SFG) spectroscopy to investigate the integration, conformation, orientation, and translocation of deuterated N-acyl-L-homoserine lactones (AHL-d(n)) with varying chain length (8, 12, and 14 C atoms) in lipid bilayers consisting of a 1:1 mixture of POPC:POPG supported on SiO(2) substrates (prepared by vesicle fusion). We found that all AHL-d(n) derivatives are well-ordered within the supported lipid bilayer (SLB) in a preferentially all-trans conformation of the deuterated alkyl chain and integrated into the upper leaflet of the SLB with the methyl terminal groups pointing downward. For the bilayer system described above, no flip-flop of AHL-d(n) from the upper leaflet to the lower one could be observed. Spectral assignments and interpretations were further supported by Fourier transform infrared and Raman spectroscopy.
Collapse
Affiliation(s)
- Christoph Barth
- Institute for Toxicology and Genetics, Karlsruhe Institute of Technology, Postfach 3640, 76021 Karlsruhe, Germany
| | - Dorota Jakubczyk
- Institute for Functional Interfaces, Karlsruhe Institute of Technology, Postfach 3640, 76021 Karlsruhe, Germany
| | - Adam Kubas
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Postfach 3640, 76021 Karlsruhe, Germany
| | - Frances Anastassacos
- Institute for Toxicology and Genetics, Karlsruhe Institute of Technology, Postfach 3640, 76021 Karlsruhe, Germany
| | - Gerald Brenner-Weiss
- Institute for Functional Interfaces, Karlsruhe Institute of Technology, Postfach 3640, 76021 Karlsruhe, Germany
| | - Karin Fink
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Postfach 3640, 76021 Karlsruhe, Germany
| | - Ute Schepers
- Institute for Toxicology and Genetics, Karlsruhe Institute of Technology, Postfach 3640, 76021 Karlsruhe, Germany
| | - Stefan Bräse
- Institute of Organic Chemistry, Karlsruhe Institute of Technology, Postfach 3640, 76021 Karlsruhe, Germany
| | - Patrick Koelsch
- National ESCA and Surface Analysis Center for Biomedical Problems, Department of Bioengineering, University of Washington, Box 35170, Seattle, WA 98195-1750
- Corresponding author.
| |
Collapse
|
19
|
Nguyen TT, Conboy JC. High-throughput screening of drug-lipid membrane interactions via counter-propagating second harmonic generation imaging. Anal Chem 2011; 83:5979-88. [PMID: 21696170 DOI: 10.1021/ac2009614] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Here we report the use of counter-propagating second harmonic generation (SHG) to image the interactions between the local anesthetic tetracaine and a multicomponent planar supported lipid bilayer array in a label-free manner. The lipid bilayer arrays, prepared using a 3D continuous flow microspotter, allow the effects of lipid phase and cholesterol content on tetracaine binding to be examined simultaneously. SHG images show that tetracaine has a higher binding affinity to liquid-crystalline phase lipids than to solid-gel phase lipids. The presence of 28 mol % cholesterol decreased the binding affinity of tetracaine to bilayers composed of the mixed chain lipid, 1-steroyl-2-oleoyl-sn-glycero-3-phophocholine (SOPC), and the saturated lipids 1,2-dimyristoyl-sn-glycero-3-phophocholine (DMPC) and 1,2-dipamitoyl-sn-glycero-3-phophocholine (DPPC) while having no effect on diunsaturated 1,2-dioleoyl-sn-glycero-3-phophocholine (DOPC). The maximum surface excess of tetracaine increases with the degree of unsaturation of the phospholipids and decreases with cholesterol in the lipid bilayers. The paper demonstrates that SHG imaging is a sensitive technique that can directly image and quantitatively measure the association of a drug to a multicomponent lipid bilayer array, providing a high-throughput means to assess drug-membrane interactions.
Collapse
Affiliation(s)
- Trang T Nguyen
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | | |
Collapse
|
20
|
Cortés E, Etchegoin PG, Le Ru EC, Fainstein A, Vela ME, Salvarezza RC. Electrochemical Modulation for Signal Discrimination in Surface Enhanced Raman Scattering (SERS). Anal Chem 2010; 82:6919-25. [DOI: 10.1021/ac101152t] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Emiliano Cortés
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata-CONICET, Sucursal 4 Casilla de Correo 16 (1900), La Plata, Argentina, The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand, Centro Atómico Bariloche and Instituto Balseiro, Comisión Nacional de Energía Atómica and Universidad Nacional de Cuyo, (8400) San Carlos de
| | - Pablo G. Etchegoin
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata-CONICET, Sucursal 4 Casilla de Correo 16 (1900), La Plata, Argentina, The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand, Centro Atómico Bariloche and Instituto Balseiro, Comisión Nacional de Energía Atómica and Universidad Nacional de Cuyo, (8400) San Carlos de
| | - Eric C. Le Ru
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata-CONICET, Sucursal 4 Casilla de Correo 16 (1900), La Plata, Argentina, The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand, Centro Atómico Bariloche and Instituto Balseiro, Comisión Nacional de Energía Atómica and Universidad Nacional de Cuyo, (8400) San Carlos de
| | - Alejandro Fainstein
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata-CONICET, Sucursal 4 Casilla de Correo 16 (1900), La Plata, Argentina, The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand, Centro Atómico Bariloche and Instituto Balseiro, Comisión Nacional de Energía Atómica and Universidad Nacional de Cuyo, (8400) San Carlos de
| | - María E. Vela
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata-CONICET, Sucursal 4 Casilla de Correo 16 (1900), La Plata, Argentina, The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand, Centro Atómico Bariloche and Instituto Balseiro, Comisión Nacional de Energía Atómica and Universidad Nacional de Cuyo, (8400) San Carlos de
| | - Roberto C. Salvarezza
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata-CONICET, Sucursal 4 Casilla de Correo 16 (1900), La Plata, Argentina, The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand, Centro Atómico Bariloche and Instituto Balseiro, Comisión Nacional de Energía Atómica and Universidad Nacional de Cuyo, (8400) San Carlos de
| |
Collapse
|
21
|
Seddon AM, Casey D, Law RV, Gee A, Templer RH, Ces O. Drug interactions with lipid membranes. Chem Soc Rev 2009; 38:2509-19. [PMID: 19690732 DOI: 10.1039/b813853m] [Citation(s) in RCA: 159] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The field of drug-membrane interactions is one that spans a wide range of scientific disciplines, from synthetic chemistry, through biophysics to pharmacology. Cell membranes are complex dynamic systems whose structures can be affected by drug molecules and in turn can affect the pharmacological properties of the drugs being administered. In this tutorial review we aim to provide a guide for those new to the area of drug-membrane interactions and present an introduction to areas of this topic which need to be considered. We address the lipid composition and structure of the cell membrane and comment on the physical forces present in the membrane which may impact on drug interactions. We outline methods by which drugs may cross or bind to this membrane, including the well understood passive and active transport pathways. We present a range of techniques which may be used to study the interactions of drugs with membranes both in vitro and in vivo and discuss the advantages and disadvantages of these techniques and highlight new methods being developed to further this field.
Collapse
Affiliation(s)
- Annela M Seddon
- Department of Chemistry, Imperial College London, Exhibition Road, South Kensington Campus, London, UK SW7 2AZ.
| | | | | | | | | | | |
Collapse
|