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Zini J, Saari H, Ciana P, Viitala T, Lõhmus A, Saarinen J, Yliperttula M. Infrared and Raman spectroscopy for purity assessment of extracellular vesicles. Eur J Pharm Sci 2022; 172:106135. [PMID: 35121019 DOI: 10.1016/j.ejps.2022.106135] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 01/28/2022] [Accepted: 01/30/2022] [Indexed: 01/15/2023]
Abstract
Extracellular vesicles (EVs) are a complex and heterogeneous population of nanoparticles involved in cell-to-cell communication. Recently, numerous studies have indicated the potential of EVs as therapeutic agents, drug carriers and diagnostic tools. However, the results of these studies are often difficult to evaluate, since different characterization methods are used to assess the purity, physical and biochemical characteristics of the EV samples. In this study, we compared four methods for the EV sample characterization and purity assessment: i) the particle-to-protein ratio based on particle analyses with nanoparticle tracking and protein concentration by bicinchoninic acid assay, ii) Western Blot analysis for specific EV biomarkers, iii) two spectroscopic lipid-to-protein ratios by either the attenuated total reflection Fourier transform infrared (ATR-FTIR) or Raman spectroscopy. The results confirm the value of Raman and ATR-FTIR spectroscopy as robust, fast and operator independent tools that require only a few microliters of EV sample. We propose that the spectroscopic lipid-to-protein (Li/Pr) ratios are reliable parameters for the purity assessment of EV preparations. Moreover, apart from determining protein concentrations, we show that ATR-FTIR spectroscopy can also be used for indirect measurements of EV concentrations. Nevertheless, the Li/Pr ratios do not represent full characterization of the EV preparations. For a complete characterization of selected EV preparations, we recommend also additional use of particle size distribution and EV biomarker analysis.
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Affiliation(s)
- Jacopo Zini
- Division of Pharmaceutical Biosciences and Drug Research Program, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland.
| | - Heikki Saari
- Division of Pharmaceutical Biosciences and Drug Research Program, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland; Finnish Red Cross Blood Service, Kivihaantie 7, Helsinki 00310, Finland
| | - Paolo Ciana
- Center of Excellence on Neurodegenerative Diseases and Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, MI, Italy
| | - Tapani Viitala
- Division of Pharmaceutical Biosciences and Drug Research Program, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland; Division of Pharmaceutical Chemistry and Technology and Drug Research Program, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Andres Lõhmus
- Division of Pharmaceutical Biosciences and Drug Research Program, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Jukka Saarinen
- Division of Pharmaceutical Chemistry and Technology and Drug Research Program, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Marjo Yliperttula
- Division of Pharmaceutical Biosciences and Drug Research Program, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland.
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2
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Biliškov N. Infrared spectroscopic monitoring of solid-state processes. Phys Chem Chem Phys 2022; 24:19073-19120. [DOI: 10.1039/d2cp01458k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We put a spotlight on IR spectroscopic investigations in materials science by providing a critical insight into the state of the art, covering both fundamental aspects, examples of its utilisation, and current challenges and perspectives focusing on the solid state.
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Affiliation(s)
- Nikola Biliškov
- Rudjer Bošković Institute, Bijenička c. 54, 10000 Zagreb, Croatia
- Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, QC, H3A 0B8, Canada
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3
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Liu X, Counil C, Shi D, Mendoza-Ortega EE, Vela-Gonzalez AV, Maestro A, Campbell RA, Krafft MP. First quantitative assessment of the adsorption of a fluorocarbon gas on phospholipid monolayers at the air/water interface. J Colloid Interface Sci 2021; 593:1-10. [DOI: 10.1016/j.jcis.2021.02.073] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 02/15/2021] [Accepted: 02/16/2021] [Indexed: 12/19/2022]
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4
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Matyszewska D, Nazaruk E, Campbell RA. Interactions of anticancer drugs doxorubicin and idarubicin with lipid monolayers: New insight into the composition, structure and morphology. J Colloid Interface Sci 2020; 581:403-416. [PMID: 32771749 DOI: 10.1016/j.jcis.2020.07.092] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/17/2020] [Accepted: 07/18/2020] [Indexed: 12/13/2022]
Abstract
We quantify directly here for the first time the extents of interactions of two different anthracycline drugs with pure and mixed lipid monolayers with respect to the surface pressure and elucidate differences in the resulting interaction mechanisms. The work concerns interactions of doxorubicin (DOx) and idarubicin (IDA) with monolayers of the zwitterionic DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) and negatively charged DMPS (1,2-dimyristoyl-sn-glycero-3-phospho-L-serine (sodium salt)) as well as a 7:3 mixture of the two lipids. These drugs are used in current cancer treatments, while the lipid systems were chosen as phosphocholines are the major lipid component of healthy cell membranes, and phosphoserines are the major lipid component that is externalized into the outer leaflet of cancerous cell membranes. It is shown that DOx interacts with DMPS monolayers to a greater extent than with DMPC monolayers by lower limits of a factor of 5 at a surface pressure of 10 mN/m and a factor of 12 at 30 mN/m. With increasing surface pressure, the small amount of drug (~0.3 µmol/m2) bound to DMPC monolayers is excluded from the interface, yet its interaction with DMPS monolayers is enhanced until there is even more drug (~3.2 µmol/m2) than lipid (~2.6 µmol/m2) at the interface. Direct evidence is presented for all systems studied that upon surface area compression lipid is reproducibly expelled from the monolayer, which we infer to be in the form of drug-lipid aggregates, yet the nature of adsorption of material back to the monolayer upon expansion is system-dependent. At 30 mN/m, most relevant to human physiology, the interactions of DOx and IDA are starkly different. For DOx, there is a conformational change in the interfacial layer driven by aggregation, resulting in the formation of lateral domains that have extended layers of drug. For the more lipophilic IDA, there is penetration of the drug into the hydrophobic acyl chain region of the monolayer and no indication of lateral segregation. In addition to the Langmuir technique, these advances were made as a result of direct measurements of the interfacial composition, structure and morphology using two different implementations of neutron reflectometry and Brewster angle microscopy. The results provide new insight into key processes that determine the uptake of drugs such as limited drug penetration through cell membranes by passive diffusion as well as activation of drug removal mechanisms related to multidrug resistance.
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Affiliation(s)
- Dorota Matyszewska
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland.
| | - Ewa Nazaruk
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
| | - Richard A Campbell
- Institut Laue-Langevin, 71 avenue des Martyrs, CS20156, 38042 Grenoble, France; Division of Pharmacy and Optometry, University of Manchester, Manchester M13 9PT, United Kingdom.
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Shah SWH, Schwieger C, Kressler J, Blume A. Monolayer behavior of pure F-DPPC and mixed films with DPPC studied by epifluorescence microscopy and infrared reflection absorption spectroscopy. Chem Phys Lipids 2020; 230:104918. [PMID: 32417099 DOI: 10.1016/j.chemphyslip.2020.104918] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 04/19/2020] [Accepted: 05/04/2020] [Indexed: 12/27/2022]
Abstract
The monolayer behavior of a l-DPPC derivative with a single fluorination in one of its terminal methyl groups (F-DPPC) at air-water interface was investigated by epifluorescence microscopy and infrared reflection absorption spectroscopy (IRRAS). Epifluorescence microscopy was utilized to study the shape and morphology of liquid-condensed (LC) domains observed upon compression of the film. IRRAS was employed for the determination of chain order and orientation. The shapes of LC-domains in a monolayer of F-DPPC are more dependent on the rate of compression than those of DPPC. The LC domains of F-DPPC display pronounced fractal growth patterns depending on the compression speed. The evolution of LC domain occurs under dominating electrostatic dipolar forces in F-DPPC. IRRAS measurements with the analysis of the frequency of the methylene stretching vibrations as a function of film compression show that the acyl chains in an F-DPPC monolayer in the LE-phase are more disordered than those in a DPPC film. The reason for the higher chain disorder in LE phase F-DPPC monolayers is a back folding of the fluorinated sn-2 chain terminus towards the air-water interface leading to larger molecular area requirement. Angular dependent IRRA spectra of monolayers at a surface pressure of 30 mN m-1 show that in the LC phase DPPC and F-DPPC exhibit a similar tilt of the acyl chains of ca. 28-30 ° relative to the surface normal. F-DPPC is ideally miscible with l-DPPC-d62 having the same chirality, as indicated by epifluorescence images and by IRRAS. However, the LC domains in an equimolar mixture of d-DPPC and F-DPPC having opposite chirality show multi-lobed complex domain patterns indicating chiral phase separation within LC domains.
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Affiliation(s)
- Syed W H Shah
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany; Department of Chemistry, Hazara University, 21120, Mansehra, Pakistan.
| | - Christian Schwieger
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany; Integrative Research Center HALOmem, Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Jörg Kressler
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Alfred Blume
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
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Wölk C, Hause G, Gutowski O, Harvey RD, Brezesinski G. Enhanced chain packing achieved via putative headgroup ion-triplet formation in binary anionic lipid/cationic surfactant mixed monolayers. Chem Phys Lipids 2019; 225:104827. [DOI: 10.1016/j.chemphyslip.2019.104827] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 08/16/2019] [Accepted: 09/17/2019] [Indexed: 11/25/2022]
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7
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Semeraro P, Syrgiannis Z, Bettini S, Giancane G, Guerra F, Fraix A, Bucci C, Sortino S, Prato M, Valli L. Singlet oxygen photo-production by perylene bisimide derivative Langmuir-Schaefer films for photodynamic therapy applications. J Colloid Interface Sci 2019; 553:390-401. [DOI: 10.1016/j.jcis.2019.06.037] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 06/06/2019] [Accepted: 06/11/2019] [Indexed: 12/15/2022]
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8
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9
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Grewal MK, Huppertz T, Vasiljevic T. FTIR fingerprinting of structural changes of milk proteins induced by heat treatment, deamidation and dephosphorylation. Food Hydrocoll 2018. [DOI: 10.1016/j.foodhyd.2018.02.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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10
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Grewal MK, Chandrapala J, Donkor O, Apostolopoulos V, Vasiljevic T. Predicting sediment formation in ultra high temperature-treated whole and skim milk using attenuated total reflectance-Fourier transform infrared spectroscopy. Int Dairy J 2017. [DOI: 10.1016/j.idairyj.2017.01.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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11
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Grewal MK, Chandrapala J, Donkor O, Apostolopoulos V, Stojanovska L, Vasiljevic T. Fourier transform infrared spectroscopy analysis of physicochemical changes in UHT milk during accelerated storage. Int Dairy J 2017. [DOI: 10.1016/j.idairyj.2016.11.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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12
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Schwieger C, Chen B, Tschierske C, Kressler J, Blume A. Organization of T-shaped facial amphiphiles at the air/water interface studied by infrared reflection absorption spectroscopy. J Phys Chem B 2012; 116:12245-56. [PMID: 22931365 DOI: 10.1021/jp306612k] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We studied the behavior of monolayers at the air/water interface of T-shaped facial amphiphiles which show liquid-crystalline mesophases in the bulk. The compounds are composed of a rigid p-terphenyl core (TP) with two terminal hydrophobic ether linked alkyl chains of equal length and one facial hydrophilic tri(ethylene oxide) chain with a carboxylic acid end group. Due to their amphiphilic nature they form stable Langmuir films at the air/water interface. Depending on the alkyl chain length they show markedly different compression isotherms. We used infrared reflection absorption spectroscopy (IRRAS) to study the changes in molecular organization of the TP films upon compression. We could retrieve information on layer thickness, alkyl chain crystallization, and the orientation of the TP cores within the films. Films of TPs with long (16 carbon atoms: TP 16/3) and short (10 carbon atoms: TP 10/3) alkyl chains were compared. Compression of TP 16/3 leads to crystallization of the terminal alkyl chains, whereas the alkyl chains of TP 10/3 stay fluid over the complete compression range. TP 10/3 shows an extended plateau in the compression isotherm which is due to a layering transition. The mechanism of this layering transition is discussed. Special attention was paid to the question of whether a so-called roll-over collapse occurs during compression. From the beginning to the end of the plateau, the layer thickness is increased from 15 to 38 Å and the orientation of the TP cores changes from parallel to the water surface to isotropic. We conclude that the plateau in the compression isotherm reflects the transition of a TP monolayer to a TP multilayer. The monolayer consists of a sublayer of well-organized TP cores underneath a sublayer of fluid alkyl chains whereas the multilayer consists of a well oriented bottom layer and a disordered top layer. Our findings do not support the model of a roll-over collapse. This study demonstrates how the IRRA band intensity of OH or OD stretching vibrations can be used to retrieve information about layer thickness and refractive indices of the film and how multicomponent IRRA bands can be fitted to retrieve information about the orientation of molecules within the monolayer.
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Affiliation(s)
- Christian Schwieger
- Institute of Chemistry, Martin-Luther-University Halle-Wittenberg, von-Dankelmann-Platz 4, D-06120 Halle (Saale), Germany.
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Nunes C, Brezesinski G, Lopes D, Lima JL, Reis S, Lúcio M. Lipid–Drug Interaction: Biophysical Effects of Tolmetin on Membrane Mimetic Systems of Different Dimensionality. J Phys Chem B 2011; 115:12615-23. [DOI: 10.1021/jp206013z] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Cláudia Nunes
- REQUIMTE, Departamento de Química, Faculdade de Farmácia, Universidade do Porto, 164, Rua Aníbal Cunha, Porto, Portugal
| | - Gerald Brezesinski
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, Am Mühlenberg 1, D-14476 Potsdam, Germany
| | - Daniela Lopes
- REQUIMTE, Departamento de Química, Faculdade de Farmácia, Universidade do Porto, 164, Rua Aníbal Cunha, Porto, Portugal
| | - José L.F.C. Lima
- REQUIMTE, Departamento de Química, Faculdade de Farmácia, Universidade do Porto, 164, Rua Aníbal Cunha, Porto, Portugal
| | - Salette Reis
- REQUIMTE, Departamento de Química, Faculdade de Farmácia, Universidade do Porto, 164, Rua Aníbal Cunha, Porto, Portugal
| | - Marlene Lúcio
- REQUIMTE, Departamento de Química, Faculdade de Farmácia, Universidade do Porto, 164, Rua Aníbal Cunha, Porto, Portugal
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14
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Nunes C, Brezesinski G, Pereira-Leite C, Lima JLFC, Reis S, Lúcio M. NSAIDs interactions with membranes: a biophysical approach. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:10847-58. [PMID: 21790169 DOI: 10.1021/la201600y] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
This work focuses on the interaction of four representative NSAIDs (nimesulide, indomethacin, meloxicam, and piroxicam) with different membrane models (liposomes, monolayers, and supported lipid bilayers), at different pH values, that mimic the pH conditions of normal (pH 7.4) and inflamed cells (pH 5.0). All models are composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) which is a representative phospholipid of most cellular membranes. Several biophysical techniques were employed: Fluorescence steady-state anisotropy to study the effects of NSAIDs in membrane microviscosity and thus to assess the main phase transition of DPPC, surface pressure-area isotherms to evaluate the adsorption and penetration of NSAIDs into the membrane, IRRAS to acquire structural information of DPPC monolayers upon interaction with the drugs, and AFM to study the changes in surface topography of the lipid bilayers caused by the interaction with NSAIDs. The NSAIDs show pronounced interactions with the lipid membranes at both physiological and inflammatory conditions. Liposomes, monolayers, and supported lipid bilayers experiments allow the conclusion that the pH of the medium is an essential parameter when evaluating drug-membrane interactions, because it conditions the structure of the membrane and the ionization state of NSAIDs, thereby influencing the interactions between these drugs and the lipid membranes. The applied models and techniques provided detailed information about different aspects of the drug-membrane interaction offering valuable information to understand the effect of these drugs on their target membrane-associated enzymes and their side effects at the gastrointestinal level.
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Affiliation(s)
- Cláudia Nunes
- REQUIMTE, Departamento de Química, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha, Porto, Portugal
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15
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Arouri A, Kerth A, Dathe M, Blume A. The binding of an amphipathic peptide to lipid monolayers at the air/water interface is modulated by the lipid headgroup structure. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:2811-2818. [PMID: 21319763 DOI: 10.1021/la104887s] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We used monolayer techniques combined with infrared reflection absorption spectroscopy (IRRAS) to study the behavior of the 18-mer cationic peptide KLA1 (KLAL KLAL KAW KAAL KLA-NH2) at the air/water interface as well as its interaction with lipid films of different composition. The adsorption of the peptide from the subphase to the air/water interface was observed measuring the increase in surface pressure (π) at constant surface area. The binding of the peptide to lipid monolayers was followed by recording the change in lipid area at a constant surface pressure (π = 30 mN m(-1)). At the air/water interface, the peptide initially adopted an α-helix at large surface area per molecule, that is, low surface pressure, but further accumulation of the peptide at the interface induced a conformational change from α-helix to intermolecular β-sheet, driven by intermolecular aggregation. When the peptide was injected into the subphase underneath lipid monolayers, it adsorbed pronouncedly to anionic monolayers containing phosphatidylglycerol forming an α-helix, but not to zwitterionic lipid monolayers. The large change in area observed upon peptide binding suggests that the peptide helix was incorporated into the apolar chain region of the lipids. An apparent partition coefficient of (0.3-1) × 10(6) M(-1) could be calculated for binding to pure POPG monolayers. Significant differences in binding affinity were observed comparing PG/PC with PG/PE monolayers, with the latter showing a higher binding constant. This shows that not only electrostatic and hydrophobic effects but also specific interactions between the headgroups of the lipids and the peptide side chains modulate the binding affinity.
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Affiliation(s)
- Ahmad Arouri
- Institute of Chemistry, Martin-Luther-University Halle-Wittenberg , von-Danckelmann-Platz 4, D-06120 Halle (Saale), Germany
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Jiang H, Guler MO, Stupp SI. The internal structure of self-assembled peptide amphiphiles nanofibers. SOFT MATTER 2007; 3:454-462. [PMID: 32900065 DOI: 10.1039/b614426h] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The self-assembly of peptide amphiphiles (PAs) into nanofibers and their bioactivity as well as physical properties have been investigated by our laboratory over the past few years. We report here on the use of transmission infrared spectroscopy (IR) and polarization modulation-infrared reflection-absorption spectroscopy (PM-IRRAS) to characterize the internal structure of the nanofibers. Depositing nanofibers flat on surfaces, and using the surface selection rules in PM-IRRAS, we demonstrate that peptide amphiphiles form β-sheets oriented parallel to the long-axis of nanofibers that pack radially from the nanofiber core. We show also that the extent of internal order depends on the molecular architecture and peptide sequence of PAs, with branched PAs yielding nanofibers with the lowest degree of internal order. Measurements of intensity and spectral position of the alkyl bands suggest that the hydrophobic core of these nanofibers can have internal order to an extent that correlates with order in their peptidic domains. We expect that bioactivity and physical properties will be controlled by the degree of internal order in these self-assembling nanostructures.
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Affiliation(s)
- Hongzhou Jiang
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Dr., Evanston, Illinois 60208-3108, USA.
| | - Mustafa O Guler
- Department of Chemistry, Northwestern University, 2220 Campus Dr., Evanston, Illinois 60208-3108, USA
| | - Samuel I Stupp
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Dr., Evanston, Illinois 60208-3108, USA. and Department of Chemistry, Northwestern University, 2220 Campus Dr., Evanston, Illinois 60208-3108, USA and Feinberg School of Medicine, Northwestern University, 2220 Campus Dr., Evanston, Illinois 60208-3108, USA and Institute for BioNanotechnology in Medicine, Northwestern University, 2220 Campus Dr., Evanston, Illinois 60208-3108, USA
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Kee BH, Sim WS, Chew W. Application of band-target entropy minimization (BTEM) and residual spectral analysis to in situ reflection–absorption infrared spectroscopy (RAIRS) data from surface chemistry studies. Anal Chim Acta 2006; 571:113-20. [PMID: 17723428 DOI: 10.1016/j.aca.2006.04.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Revised: 04/11/2006] [Accepted: 04/13/2006] [Indexed: 11/29/2022]
Abstract
The band-target entropy minimization (BTEM) curve resolution technique has been used to analyze in situ reflection-absorption infrared spectroscopy (RAIRS) data of CO chemisorption on Ni(111) single crystal surfaces. The bilinearity assumption for pRAIRS data, that is, negative logarithm to the base 10 of raw reflectance RAIRS data, was found to be sufficiently valid for the test data. A total of 11 real pure component pRAIRS spectra were elucidated via BTEM in tandem with an iterative residual spectral data analysis. Furthermore, 2 abstract pure component right singular vectors were found to account for all the pRAIRS non-linearities, baseline drifts and other spectral noise. In total, 100.2% of the pRAIRS signals were accounted for by these 13 spectral components. The 11 real pure component pRAIRS spectra and their corresponding relative concentration kinetic sequences correlate with 6 well-known adsorbed CO domain structures. Moreover, amongst the BTEM resolved spectra were five new bands that were not previously observed using conventional visual identification methods adopted by surface chemists. These new bands engendered new understanding to the mechanism of CO chemisorption on Ni(111). The combination of BTEM with residual spectral analysis was thus demonstrated to be efficacious for curve resolution of in situ RAIRS data obtained from surface chemistry studies.
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Affiliation(s)
- Boon Hong Kee
- Institute of Chemical and Engineering Sciences, 1 Pesek Road, Jurong Island, Singapore 627833, Singapore
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Campbell RA, Day JPR, Bain CD. External reflection Fourier transform infrared spectroscopy of surfactants at the air-water interface: separation of bulk and adsorbed surfactant signals. APPLIED SPECTROSCOPY 2005; 59:993-1001. [PMID: 16105207 DOI: 10.1366/0003702054615241] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
External reflection Fourier transform infrared spectroscopy (ERFTIRS) has been used to obtain spectra of monolayers of the hydrocarbon surfactant octaethylene glycol monodecyl ether (C(10)E(8)) and the fluorocarbon surfactant ammonium perfluorononanoate (APFN) at the expanding liquid surface of an overflowing cylinder. The use of target factor analysis (TFA) to separate out the contributions of water, adsorbed surfactant, and dissolved surfactant is demonstrated. For both surfactants, there is a linear relationship between the component weight of the adsorbed surfactant, obtained by TFA, and the surface excess determined independently by ellipsometry or neutron reflection. This linear relationship suggests that the monolayers behave like isotropic films with a constant density. A sensitivity of less than 10% of a monolayer is demonstrated. The benefits of using a multivariate curve fitting procedure to analyze sets of ER-FTIR spectra are discussed and some potential pitfalls are identified. This technique is also applicable to static interfaces.
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Affiliation(s)
- Richard A Campbell
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, UK
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Hussain H, Kerth A, Blume A, Kressler J. Amphiphilic Block Copolymers of Poly(ethylene oxide) and Poly(perfluorohexylethyl methacrylate) at the Water Surface and Their Penetration into the Lipid Monolayer. J Phys Chem B 2004. [DOI: 10.1021/jp0495702] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- H. Hussain
- Department of Engineering Science and Department of Chemistry, Martin-Luther-University Halle-Wittenberg, D-06099 Halle (Saale), Germany
| | - A. Kerth
- Department of Engineering Science and Department of Chemistry, Martin-Luther-University Halle-Wittenberg, D-06099 Halle (Saale), Germany
| | - A. Blume
- Department of Engineering Science and Department of Chemistry, Martin-Luther-University Halle-Wittenberg, D-06099 Halle (Saale), Germany
| | - J. Kressler
- Department of Engineering Science and Department of Chemistry, Martin-Luther-University Halle-Wittenberg, D-06099 Halle (Saale), Germany
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Flach CR, Cai P, Dieudonné D, Brauner JW, Keough KMW, Stewart J, Mendelsohn R. Location of structural transitions in an isotopically labeled lung surfactant SP-B peptide by IRRAS. Biophys J 2003; 85:340-9. [PMID: 12829488 PMCID: PMC1303089 DOI: 10.1016/s0006-3495(03)74478-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Pulmonary surfactant, a lipid/protein complex that lines the air/water interface in the mammalian lung, functions to reduce the work of breathing. Surfactant protein B (SP-B) is a small, hydrophobic protein that is an essential component of this mixture. Structure-function relationships of SP-B are currently under investigation as the protein and its peptide analogs are being incorporated into surfactant replacement therapies. Knowledge of the structure of SP-B and its related peptides in bulk and monolayer phases will facilitate the design of later generation therapeutic agents. Prior infrared reflection-absorption spectroscopic studies reported notable, reversible surface pressure-induced antiparallel beta-sheet formation in a synthetic peptide derived from human SP-B, residues 9-36 (SP-B(9-36)). In the current work, infrared reflection-absorption spectroscopy is applied in conjunction with isotopic labeling to detect the site and pressure dependence of the conformational change. SP-B(9-36), synthesized with (13)C=O-labeled Ala residues in positions 26, 28, 30, and 32, shifted the beta-sheet marker band to approximately 1600 cm(-1) and thus immediately identified this structural element within the labeled region. Surface pressure-induced alterations in the relative intensities of Amide I band constituents are interpreted using a semiempirical transition dipole coupling model. In addition, electron micrographs reveal the formation of tubular myelin structures from in vitro preparations using SP-B(9-36) in place of porcine SP-B indicating that the peptide has the potential to mimic this property of the native protein.
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Affiliation(s)
- Carol R Flach
- Department of Chemistry, Newark College of Arts and Sciences, Rutgers University, Newark, New Jersey, USA.
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Brauner JW, Flach CR, Xu Z, Bi X, Lewis RNAH, McElhaney RN, Gericke A, Mendelsohn R. Quantitative Functional Group Orientation in Langmuir Films by Infrared Reflection−Absorption Spectroscopy: CO Groups in Behenic Acid Methyl Ester and sn2-13C-DSPC. J Phys Chem B 2003. [DOI: 10.1021/jp030066r] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Joseph W. Brauner
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G2H7, Department of Chemistry, Kent State University, Kent, Ohio 44242, and Department of Chemistry, Newark College of Arts and Science, Rutgers University, 73 Warren Street, Newark, New Jersey 07102
| | - Carol R. Flach
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G2H7, Department of Chemistry, Kent State University, Kent, Ohio 44242, and Department of Chemistry, Newark College of Arts and Science, Rutgers University, 73 Warren Street, Newark, New Jersey 07102
| | - Zhi Xu
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G2H7, Department of Chemistry, Kent State University, Kent, Ohio 44242, and Department of Chemistry, Newark College of Arts and Science, Rutgers University, 73 Warren Street, Newark, New Jersey 07102
| | - Xiaohong Bi
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G2H7, Department of Chemistry, Kent State University, Kent, Ohio 44242, and Department of Chemistry, Newark College of Arts and Science, Rutgers University, 73 Warren Street, Newark, New Jersey 07102
| | - Ruthven N. A. H. Lewis
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G2H7, Department of Chemistry, Kent State University, Kent, Ohio 44242, and Department of Chemistry, Newark College of Arts and Science, Rutgers University, 73 Warren Street, Newark, New Jersey 07102
| | - Ronald N. McElhaney
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G2H7, Department of Chemistry, Kent State University, Kent, Ohio 44242, and Department of Chemistry, Newark College of Arts and Science, Rutgers University, 73 Warren Street, Newark, New Jersey 07102
| | - Arne Gericke
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G2H7, Department of Chemistry, Kent State University, Kent, Ohio 44242, and Department of Chemistry, Newark College of Arts and Science, Rutgers University, 73 Warren Street, Newark, New Jersey 07102
| | - Richard Mendelsohn
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G2H7, Department of Chemistry, Kent State University, Kent, Ohio 44242, and Department of Chemistry, Newark College of Arts and Science, Rutgers University, 73 Warren Street, Newark, New Jersey 07102
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