Abstract
Lipids are important natural chemical compounds, as they comprise the major component in biological membranes. Biological membranes are composed of lipids in a bilayer structure and proteins incorporated into the bilayers or bound to the bilayer surface. Due to the amphiphilic nature of lipids, they self-assemble in aqueous solution into a variety of lyotropic phases, the most important one being the lamellar phase made up of stacks of lipid bilayers separated by water layers. The bilayer structure can be easily produced by dispersing lipids in water. Lipids are amphiphilic structures built up of a polar headgroup and one or two hydrophobic alkyl chains. They are, therefore, surface active and form the so-called insoluble monolayers or Langmuir films at the air–water interface. These monolayers resemble half of a lipid bilayer and are, therefore, widely used as model systems for bilayer membranes. In this review, the properties and the phase behavior of phospholipid monolayers, as well as the techniques used for studying these monolayers will be described. In addition, examples for the information gained using different techniques will be shown.
Similar content being viewed by others
Notes
Irving Langmuir was born in 1881 in New York and died in 1957 in Woods Hole, USA. In 1932 he was awarded with the Nobel-Prize in Chemistry for his “discoveries and investigations in surface chemistry”. He worked together with Katherine Blodgett on surface adsorption phenomena and on thin films. They developed the concept of a “monolayer”, i.e. a single layer of molecules on a surface. In honor of Langmuir, monolayers of sparingly soluble molecules at the air–water interface were named after him.
Ludwig Ferdinand Wilhelmy was born in 1812 in Stargard, Germany and died in 1864 in Berlin, Germany. From 1849 till 1854 he was academic lecturer at the University of Heidelberg, Germany. In 1863, he published his article on the use of the “Wilhelmy plate” for measuring the surface tension of liquids in the famous journal “Annalen der Physik”.
The surface tension γ is a property of a fluid interface to acquire the least surface area possible. This property arises from the fact that the attractive forces between the molecules in the liquid are higher (cohesion) than the force between molecules in the gas phase and the liquid surface (adsorption). This leads to a net force being directed inward into the liquid and the appearance of the surface as if it were covered by an elastic membrane under tension. Therefore, the term “surface tension” was coined. The surface tension has the dimension of a force per unit length (N m−1), which is equivalent to an energy per unit area (J m−2). Therefore, in many cases the term surface energy is also used. Attractive forces between water molecules in liquid water are very high, because of the occurrence of hydrogen bonds between molecules. Therefore, the surface tension of pure water is also very high with 72 mN m−1, much higher than for other ordinary organic liquids. If the surface is covered by amphiphilic substances, the surface tension decreases, because the attractive forces between these molecules are much lower.
Phase transitions in three dimensions are classified according to Paul Ehrenfest [45, 46]. The classification is based on the properties of the derivatives of the thermodynamic free energy, for instance, the Gibbs free energy with respect to other thermodynamic variables. If the first derivative is discontinuous, then the phase transition is of first order. If the first derivative is continuous and the second derivative discontinuous, then the transition is of second order, etc. Solid–liquid, liquid–gas, and solid–gas transitions of bulk materials are of first order. The terminology was taken over to the classification of two-dimensional transition, i.e., Langmuir monolayers at the air–water interface.
Many fluorescence microscopes used in biophysical studies are of the epifluorescence design (see Fig. 8). The light coming from the excitation light source first passes through an optic filter, where the appropriate wave length for excitation of the fluorescent molecule is selected. The excitation light then passes through a dichroic mirror where it is reflected and focused onto the sample by the objective lens. Light with the wave length of the excitation light reflected from the sample is reflected by the dichroic mirror into the light source. The fluorescence light with a longer wave length emitted from the sample passes through the same objective lens and then is not reflected by the dichroic mirror but passes through the dichroic mirror and through the emission filter which prevents residual excitation light reaching the detector. The emitted light is then focused onto the detector, in this case a high sensitivity CCD camera.
In a GIXD experiment, the incident beam is a monochromatic X-ray beam with a defined wavelength. The beam is adjusted so that it strikes the water surface at an angle just below the critical angle αc for total external reflection at the chosen wavelength. This critical angle αc for total reflection is ~ 0.13° for a wavelength of 0.138 nm (= 9000 eV photon energy). When the beam is totally reflected a so-called evanescent wave travels along the surface of the air–water interface. The penetration depth of this wave is ca. 8 nm, i.e. somewhat larger than the thickness of a typical lipid monolayer. If the monolayer covering the surface has an ordered structure with crystallites, Bragg scattering can occur. The crystallites should be oriented such that lattice planes have an angle Θhk relative to the evanescent beam so that the condition λ = 2dhk sin Θhk for Bragg scattering is fulfilled.
In infrared spectroscopy (IR) the sample is irradiated with radiation covering the infrared region of the electromagnetic spectrum. The so-called mid-IR is the wavelength region between 2.5 and 25 µm, which is equivalent to the wavenumber region between 4000 and 400 cm−1. This type of radiation excites vibrational modes of the molecules under investigation. Organic molecules have a number of vibrational modes which are characteristic for certain “group vibrations”, for instance, the C=O group or the CH2-groups in aliphatic chains of lipids. The IR spectrum shows typical absorption bands which can be analyzed with respect to their frequency (wavenumber) and intensity.
References
Singer SJ, Nicolson GL (1972) Fluid mosaic model of structure of cell membranes. Science 175(4023):720–731. https://doi.org/10.1126/science.175.4023.720
Nicolson GL (2014) The fluid-mosaic model of membrane structure: still relevant to understanding the structure, function and dynamics of biological membranes after more than 40 years. Biochim Biophys Acta 1838(6):1451–1466. https://doi.org/10.1016/j.bbamem.2013.10.019
Bagatolli LA, Ipsen JH, Simonsen AC, Mouritsen OG (2010) An outlook on organization of lipids in membranes: searching for a realistic connection with the organization of biological membranes. Prog Lipid Res 49(4):378–389. https://doi.org/10.1016/j.plipres.2010.05.001
Gennis RB (1990) Biomembranes: molecular structure and function. Springer-Verlag, New York
Buehler LK (2016) Cell membranes. Garland Science, New York
Adamson AW, Gast AP (1997) Physical chemistry of surfaces, 6th edn. Wiley, New York
Butt H-J, Graf K, Kappl M (2013) Physics and chemistry of interfaces, 3rd edn. Wiley-VCH, Weinheim
Evans RW (1995) Aggregates of saturated phospholipids at the air-water interface. Chem Phys Lipids 78(2):163–175. https://doi.org/10.1016/0009-3084(95)02495-5
Blume A (1979) A comparative study of the phase transitions of phospholipid bilayers and monolayers. Biochim Biophys Acta 557(1):32–44. https://doi.org/10.1016/0005-2736(79)90087-7
Brockman H (1999) Lipid monolayers: why use half a membrane to characterize protein-membrane interactions?. Curr Opin Struct Biol 9(4):438–443. https://doi.org/10.1016/s0959-440x(99)80061-x
Maget-Dana R (1999) The monolayer technique: a potent tool for studying the interfacial properties of antimicrobial and membrane-lytic peptides and their interactions with lipid membranes. Biochim Biophys Acta 1462(1–2):109–140. https://doi.org/10.1016/s0005-2736(99)00203-5
Möhwald H (1990) Phospholipid and phospholipid-protein monolayers at the air-water interface. Annu Rev Phys Chem 41:441–476
Giner-Casares JJ, Brezesinski G, Möhwald H (2014) Langmuir monolayers as unique physical models. Curr Opin Colloid Interface Sci 19(3):176–182. https://doi.org/10.1016/j.cocis.2013.07.006
Stefaniu C, Brezesinski G, Mohwald H (2014) Langmuir monolayers as models to study processes at membrane surfaces. Adv Colloid Interface Sci 208:197–213. https://doi.org/10.1016/j.cis.2014.02.013
Pichot R, Watson R, Norton I (2013) Phospholipids at the interface: current trends and challenges. Int J Mol Sci 14(6):11767–11794. https://doi.org/10.3390/ijms140611767
Giehl A, Lemm T, Bartelsen O, Sandhoff K, Blume A (1999) Interaction of the GM2-activator protein with phospholipid–ganglioside bilayer membranes and with monolayers at the air–water interface. Eur J Biochem 261(3):650–658. https://doi.org/10.1046/j.1432-1327.1999.00302.x
Calvez P, Bussières S, Éric D, Salesse C (2009) Parameters modulating the maximum insertion pressure of proteins and peptides in lipid monolayers. Biochimie 91(6):718–733. https://doi.org/10.1016/j.biochi.2009.03.018
Kaganer VM, Möhwald H, Dutta P (1999) Structure and phase transitions in Langmuir monolayers. Rev Mod Phys 71(3):779–819. https://doi.org/10.1103/RevModPhys.71.779
Stefaniu C, Brezesinski G (2014) Grazing incidence X-ray diffraction studies of condensed double-chain phospholipid monolayers formed at the soft air/water interface. Adv Colloid Interface Sci 207:265–279. https://doi.org/10.1016/j.cis.2014.01.005
Stefaniu C, Brezesinski G (2014) X-ray investigation of monolayers formed at the soft air/water interface. Curr Opin Colloid Interface Sci 19(3):216–227. https://doi.org/10.1016/j.cocis.2014.01.004
Bangham AD, Mason W (1979) The effect of some general anaesthetics on the surface potential of lipid monolayers. Br J Pharmacol 66(2):259–265. https://doi.org/10.1111/j.1476-5381.1979.tb13674.x
Cadenhead DA, Kellner BMJ (1974) Some observations on monolayer spreading solvents with special reference to phospholipid monolayers. J Colloid Interface Sci 49(1):143–145. https://doi.org/10.1016/0021-9797(74)90311-7
Clarke RJ (2001) The dipole potential of phospholipid membranes and methods for its detection. Adv Colloid Interface Sci 89–90:263–281. https://doi.org/10.1016/s0001-8686(00)00061-0
Haydon DA, Elliott JR (1986) Surface potential changes in lipid monolayers and the ‘cut-off’ in anaesthetic effects of N-alkanols. Biochim Biophys Acta 863(2):337–340. https://doi.org/10.1016/0005-2736(86)90278-6
Wang L (2012) Measurements and implications of the membrane dipole potential. Annu Rev Biochem 81(1):615–635. https://doi.org/10.1146/annurev-biochem-070110-123033
Lösche M, Duwe HP, Möhwald H (1988) Quantitative analysis of surface textures in phospholipid monolayer phase transitions. J Coll Interf Sci 126:432–444
Lösche M, Möhwald H (1984) Impurity controlled phase transitions of phospholipid monolayers. Eur Biophys J 11:35–42
McConnell HM (1984) Periodic structures in lipid monolayer phase transitions. Proc Natl Acad Sci USA 81:3249–3253
Hönig D, Möbius D (1991) Direct visualization of monolayers at the air-water interface by Brewster angle microscopy. J Phys Chem 95(12):4590–4592. https://doi.org/10.1021/j100165a003
Hénon S, Meunier J (1991) Microscope at the Brewster angle: direct observation of first-order phase transitions in monolayers. Rev Sci Instrum 62(4):936–939. https://doi.org/10.1063/1.1142032
Mobius D (1996) Light microscopy of organized monolayers. Curr Opin Colloid Interface Sci 1(2):250–256. https://doi.org/10.1016/s1359-0294(96)80012-4
Vollhardt D (2014) Brewster angle microscopy: a preferential method for mesoscopic characterization of monolayers at the air/water interface. Curr Opin Colloid Interface Sci 19(3):183–197. https://doi.org/10.1016/j.cocis.2014.02.001
Blume A, Kerth A (2013) Peptide and protein binding to lipid monolayers studied by FT-IRRAS. Biochim Biophys Acta 1828(10):2294–2305. https://doi.org/10.1016/j.bbamem.2013.04.014
Blaudez D, Buffeteau T, Desbat B, Turlet JM (1999) Infrared and Raman spectroscopies of monolayers at the air-water interface. Curr Opin Colloid Interface Sci 4:265–272
Dluhy RA, Cornell DG (1985) In situ measurements of the infrared-spectra of insoluble monolayers at the air–water interface. J Phys Chem 89(15):3195–3197. https://doi.org/10.1021/j100261a006
Mendelsohn R, Brauner JW, Gericke A (1995) External infrared reflection-absorption spectrometry of monolayer films at the air–water interface. Annu Rev Phys Chem 46:305–334. https://doi.org/10.1146/annurev.physchem.46.1.305
Mendelsohn R, Mao GR, Flach CR (2010) Infrared reflection–absorption spectroscopy: principles and applications to lipid-protein interaction in Langmuir films. Biochim Biophys Acta 1798(4):788–800. https://doi.org/10.1016/j.bbamem.2009.11.024
Chen X, Clarke ML, Wang JIE, Chen Z (2005) Sum frequency generation vibrational spectroscopy studies on molecular conformation and orientation of biological molecules at interfaces. Int J Mod Phys B 19(04):691–713. https://doi.org/10.1142/s0217979205029341
Roke S, Schins J, Müller M, Bonn M (2003) Vibrational spectroscopic investigation of the phase diagram of a biomimetic lipid monolayer. Phys Rev Lett. https://doi.org/10.1103/PhysRevLett.90.128101
Watry MR, Tarbuck TL, Richmond GL (2003) Vibrational sum-frequency studies of a series of phospholipid monolayers and the associated water structure at the vapor/water interface. J Phys Chem B 107(2):512–518. https://doi.org/10.1021/jp0216878
Blume A (2004) Lipids. In: Walz D, Teissié J, Milazzo G (eds) Bioelectrochemistry of membranes, vol V. Birkhäuser-Verlag, Basel, pp 61–152
Bard AJ, Inzelt G, Scholz F (2012) Electrochemical dictionary, 2nd edn. Springer, Berlin
Wilhelmy L (1863) Ueber die Abhängigkeit der Capillaritäts-Constanten des Alkohols von Substanz und Gestalt des benetzten festen Körpers. Annalen der Physik Chemie 195(6):177–217. https://doi.org/10.1002/andp.18631950602
Lee KYC (2008) Collapse mechanisms of Langmuir monolayers. Annu Rev Phys Chem 59(1):771–791. https://doi.org/10.1146/annurev.physchem.58.032806.104619
Atkins P, de Paula J (2010) Physical chemistry, 9th edn edn. Oxford University Press, Oxford
Jaeger G (1998) The Ehrenfest classification of phase transitions: introduction and evolution. Arch Hist Exact Sci 53(1):51–81. https://doi.org/10.1007/s004070050021
Gaines GL (1966) Insoluble monolayers at liquid–gas interfaces. Wiley Interscience, New York
Hoffmann S (1997) Struktur und Dynamik langkettiger 5-n-Alkylresorcinole in Phospholipidmodellmembranen, Ph.D., University of Kaiserslautern, Kaiserslautern
Risović D, Frka S, Kozarac Z (2011) Application of Brewster angle microscopy and fractal analysis in investigations of compressibility of Langmuir monolayers. J Chem Phys 134(2):024701. https://doi.org/10.1063/1.3522646
Caruso B, Mangiarotti A, Wilke N (2013) Stiffness of lipid monolayers with phase coexistence. Langmuir 29(34):10807–10816. https://doi.org/10.1021/la4018322
Duncan SL, Larson RG (2008) Comparing experimental and simulated pressure-area isotherms for DPPC. Biophys J 94(8):2965–2986. https://doi.org/10.1529/biophysj.107.114215
Crane JM, Putz G, Hall SB (1999) Persistence of phase coexistence in disaturated phosphatidylcholine monolayers at high surface pressures. Biophys J 77(6):3134–3143. https://doi.org/10.1016/s0006-3495(99)77143-2
Adams EM, Casper CB, Allen HC (2016) Effect of cation enrichment on dipalmitoylphosphatidylcholine (DPPC) monolayers at the air–water interface. J Colloid Interface Sci 478:353–364. https://doi.org/10.1016/j.jcis.2016.06.016
von Tscharner V, McConnell HM (1981) An alternative view of phospholipid phase behavior at the air–water interface. Microscope and film balance studies. Biophys J 36(2):409–419. https://doi.org/10.1016/s0006-3495(81)84740-6
Träuble H, Eibl H (1974) Electrostatic effects on lipid phase transitions: membrane structure and ionic environment. Proc Natl Acad Sci USA 71(1):214–219
Blume A, Eibl H (1979) The influence of charge on bilayer membranes calorimetric investigations of phosphatidic acid bilayers. Biochim Biophys Acta 558(1):13–21. https://doi.org/10.1016/0005-2736(79)90311-0
Blume A, Tuchtenhagen J (1992) Thermodynamics of ion binding to phosphatidic acid bilayers. Titration calorimetry of the heat of dissociation of DMPA. Biochemistry 31(19):4636–4642. https://doi.org/10.1021/bi00134a014
Eibl H, Blume A (1979) The influence of charge on phosphatidic acid bilayer membranes. Biochim Biophys Acta 553(3):476–488. https://doi.org/10.1016/0005-2736(79)90303-1
Garidel P (1997) The negatively charged phospholipids phosphatidic acid and phosphatidylglycerol, Ph.D, University of Kaiserslautern, Kaiserslautern
Garidel P, Blume A (2005) 1,2-Dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) monolayers: influence of temperature, pH, ionic strength and binding of alkaline earth cations. Chem Phys Lipids 138(1–2):50–59. https://doi.org/10.1016/j.chemphyslip.2005.08.001
Kodama M, Shibata O, Nakamura S, Lee S, Sugihara G (2004) A monolayer study on three binary mixed systems of dipalmitoyl phosphatidyl choline with cholesterol, cholestanol and stigmasterol. Colloid Surf B Biointerface 33(3–4):211–226. https://doi.org/10.1016/j.colsurfb.2003.10.008
Gerdon S, Hoffmann S, Blume A (1994) Properties of mixed monolayers and bilayers of long-chain 5-n-alkylresorcinols and dipalmitoylphosphatidylcholine. Chem Phys Lipids 71(2):229–243. https://doi.org/10.1016/0009-3084(94)90074-4
Gaines GL (1966) Thermodynamic relationships for mixed insoluble monolayers. J Colloid Interface Sci 21(3):315–319. https://doi.org/10.1016/0095-8522(66)90015-8
Hildebrandt HJ (1929) Solubility (XII). Regular solutions. J Am Chem Soc 51:66–80
Garidel P, Johann C, Blume A (2000) Thermodynamics of lipid organization and domain formation in phospholipid bilayers. J Liposome Res 10(2–3):131–158. doi:https://doi.org/10.3109/08982100009029383
Matuo H, Motomura K, Matuura R (1982) Interrelationships between two-dimensional phase diagrams and mean molecular area-mole fraction curves in mixed monolayers. Chem Phys Lipids 30(4):353–365. https://doi.org/10.1016/0009-3084(82)90029-9
Matuo H, Motomura K, Matuura R (1982) Mixed monolayers of dipalmitoylglycerophosphocholine, distearoylglycerophosphocholine and 1-palmitoylglycerol. Chem Phys Lipids 31(1):53–60. https://doi.org/10.1016/0009-3084(82)90018-4
Matuo H, Motomura K, Matuura R (1981) Effects of molecular structure on two-dimensional phase diagram and thermodynamic quantities of mixed monolayers. Chem Phys Lipids 28(4):385–397. https://doi.org/10.1016/0009-3084(81)90024-4
Matuo H, Motomura K, Matuura R (1982) Mixed monolayers of fatty acids with distearoylglycerophosphocholine. Chem Phys Lipids 31(4):351–358. https://doi.org/10.1016/0009-3084(82)90071-8
Stottrup BL, Nguyen AH, Tüzel E (2010) Taking another look with fluorescence microscopy: image processing techniques in Langmuir monolayers for the twenty-first century. Biochim Biophys Acta 1798(7):1289–1300. https://doi.org/10.1016/j.bbamem.2010.01.003
Weis RM (1991) Fluorescence microscopy of phospholipid monolayer phase transitions. Chem Phys Lipids 57(2–3):227–239. https://doi.org/10.1016/0009-3084(91)90078-p
Scholtysek P, Li Z, Kressler J, Blume A (2012) Interactions of DPPC with semitelechelic poly(glycerol methacrylate)s with perfluoroalkyl endgroups. Langmuir 28(44):15651–15662. https://doi.org/10.1021/la3028226
Scholtysek P (2014) Chirale und achirale Polymere in Wechselwirkung mit Phospholipid-Monolayern und—Bilayern. Ph.D., Martin-Luther-University Halle-Wittenberg, Halle
Cristofolini L (2014) Synchrotron X-ray techniques for the investigation of structures and dynamics in interfacial systems. Curr Opin Colloid Interface Sci 19(3):228–241. https://doi.org/10.1016/j.cocis.2014.03.006
Flach CR, Brauner JW, Mendelsohn R (1993) Calcium ion interactions with insoluble phospholipid monolayer films at the A/W interface. External reflection-absorption IR studies. Biophys J 65(5):1994–2001. https://doi.org/10.1016/s0006-3495(93)81276-1
Flach CR, Gericke A, Mendelsohn R (1997) Quantitative determination of molecular chain tilt angles in monolayer films at the air/water interface: Infrared reflection/absorption spectroscopy of behenic acid methyl ester. J Phys Chem B 101(1):58–65. https://doi.org/10.1021/jp962288d
Kerth A (2003) Infrarot-Reflexions-Absorptions-Spektroskopie an Lipid-, Peptid- und Flüssigkristall-Filmen an der Luft/Wasser-Grenzfläche. Ph.D., Martin-Luther-University Halle-Wittenberg, Halle
Kuzmin VL, Mikhailov AV (1981) Molecular theory of light reflection and applicability limits of the macroscopic approach. Opt Spectrosc (USSR) 51:383–385
Gericke A, Flach CR, Mendelsohn R (1997) Structure and orientation of lung surfactant SP-C and L-alpha-dipalmitoylphosphatidylcholine in aqueous monolayers. Biophys J 73(1):492–499
Kerth A, Brehmer T, Meister A, Hanner P, Jakob M, Klösgen RB, Blume A (2012) Interaction of a tat substrate and a tat signal peptide with thylakoid lipids at the air–water interface. Chem Bio Chem 13(2):231–239. https://doi.org/10.1002/cbic.201100458
Kerth A, Erbe A, Dathe M, Blume A (2004) Infrared reflection absorption spectroscopy of amphipathic model peptides at the air/water interface. Biophys J 86(6):3750–3758. https://doi.org/10.1529/biophysj.103.035964
Meister A, Nicolini C, Waldmann H, Kuhlmann J, Kerth A, Winter R, Blume A (2006) Insertion of lipidated ras proteins into lipid monolayers studied by infrared reflection absorption spectroscopy (IRRAS). Biophys J 91(4):1388–1401. https://doi.org/10.1529/biophysj.106.084624
Blume A (1996) Properties of lipid vesicles: FT-IR spectroscopy and fluorescence probe studies. Curr Opin Colloid Interface Sci 1(1):64–77. https://doi.org/10.1016/s1359-0294(96)80046-x
Mantsch HH, McElhaney RN (1991) Phospholipid phase transitions in model and biological membranes as studied by infrared spectroscopy. Chem Phys Lipids 57(2–3):213–226. https://doi.org/10.1016/0009-3084(91)90077-o
Sung W, Kim D, Shen YR (2013) Sum-frequency vibrational spectroscopic studies of Langmuir monolayers. Curr Appl Phys 13(4):619–632. https://doi.org/10.1016/j.cap.2012.12.002
Nihonyanagi S, Yamaguchi S, Tahara T (2017) Ultrafast dynamics at water interfaces studied by vibrational sum frequency generation spectroscopy. Chem Rev 117(16):10665–10693. https://doi.org/10.1021/acs.chemrev.6b00728
Chung C-Y, Potma EO (2013) Biomolecular imaging with coherent nonlinear vibrational microscopy. Annu Rev Phys Chem 64(1):77–99. https://doi.org/10.1146/annurev-physchem-040412-110103
Jubb AM, Hua W, Allen HC (2012) Environmental chemistry at vapor/water interfaces: insights from vibrational sum frequency generation spectroscopy. Annu Rev Phys Chem 63(1):107–130. https://doi.org/10.1146/annurev-physchem-032511-143811
Sovago M, Vartiainen E, Bonn M (2009) Observation of buried water molecules in phospholipid membranes by surface sum-frequency generation spectroscopy. J Chem Phys 131(16):161107. https://doi.org/10.1063/1.3257600
Sovago M, Vartiainen E, Bonn M (2010) Erratum: “Observation of buried water molecules in phospholipid membranes by surface sum-frequency generation spectroscopy”. [J Chem Phys 131, 161107 (2009)]. J Chem Phys 133(22):229901. https://doi.org/10.1063/1.3511705
Feng R-J, Li X, Zhang Z, Lu Z, Guo Y (2016) Spectral assignment and orientational analysis in a vibrational sum frequency generation study of DPPC monolayers at the air/water interface. J Chem Phys 145(24):244707. https://doi.org/10.1063/1.4972564
Chen X, Hua W, Huang Z, Allen HC (2010) Interfacial water structure associated with phospholipid membranes studied by phase-sensitive vibrational sum frequency generation spectroscopy. J Am Chem Soc 132(32):11336–11342. https://doi.org/10.1021/ja1048237
Ma G, Allen HC (2006) DPPC Langmuir monolayer at the air–water interface: probing the tail and head groups by vibrational sum frequency generation spectroscopy. Langmuir 22(12):5341–5349. https://doi.org/10.1021/la0535227
Hadicke A, Blume A (2013) Interactions of Pluronic block copolymers with lipid monolayers studied by epi-fluorescence microscopy and by adsorption experiments. J Colloid Interface Sci 407(327–338):327–338. https://doi.org/10.1016/j.jcis.2013.06.041
Amado E, Kerth A, Blume A, Kressler J (2009) Phospholipid crystalline clusters induced by adsorption of novel amphiphilic triblock copolymers to monolayers. Soft Matter 5(3):669–675. doi:https://doi.org/10.1039/B813994f
Arouri A, Kerth A, Dathe M, Blume A (2011) The binding of an amphipathic peptide to lipid monolayers at the air/water interface is modulated by the lipid headgroup structure. Langmuir 27(6):2811–2818. https://doi.org/10.1021/la104887s
Erbe A, Kerth A, Dathe M, Blume A (2009) Interactions of KLA amphipathic model peptides with lipid monolayers. Chem Bio Chem 10(18):2884–2892. https://doi.org/10.1002/cbic.200900444
Hadicke A, Blume A (2015) Binding of short cationic peptides (KX)4K to negatively charged DPPG monolayers: competition between electrostatic and hydrophobic interactions. Langmuir 31(44):12203–12214. https://doi.org/10.1021/acs.langmuir.5b02882
Hadicke A, Blume A (2016) Binding of the cationic peptide (KL)4K to lipid monolayers at the air-water interface: effect of lipid headgroup charge, acyl chain length, and acyl chain saturation. J Phys Chem B 120(16):3880–3887. https://doi.org/10.1021/acs.jpcb.6b01558
Brehmer T, Kerth A, Graubner W, Malesevic M, Hou B, Bruser T, Blume A (2012) Negatively charged phospholipids trigger the interaction of a bacterial tat substrate precursor protein with lipid monolayers. Langmuir 28(7):3534–3541. https://doi.org/10.1021/la204473t
Kerth A, Garidel P, Howe J, Alexander C, Mach J-P, Waelli T, Blume A, Rietschel ETh, Brandenburg K (2009) an infrared reflection–absorption spectroscopic (IRRAS) study of the interaction of Lipid A and lipopolysaccharide re with endotoxin-binding proteins. Med Chem 5(6):535–542. https://doi.org/10.2174/157340609790170452
Acknowledgements
This work was supported by Grants from the Deutsche Forschungsgemeinschaſt (DFG), the state of Saxonia-Anhalt, the Phospholipid Research Center, Heidelberg, Germany, and Boehringer Ingelheim GmbH and Co, Ingelheim, Germany. I want to express my gratitude to all members of my group for their contributions to the research results presented here in this review.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Blume, A. Lipids at the air–water interface. ChemTexts 4, 3 (2018). https://doi.org/10.1007/s40828-018-0058-z
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s40828-018-0058-z