Lipid monolayer

S-layer protein was crystallized on lipid monolayers lipid bilayer membranes and liposome. 

Step 2 - A patch pipet is removed from the solution, the polar head groups of the monolayer lipids are adsorbed to the interface while the fatty acid hydrophobic tails are exposed to the air ... 

In order to verify that the adsorbed lipid membrane indeed forms a bilayer film, another experiment is conducted with an aim to detect the formation of a monolayer lipid. It starts with a piranha-cleaned micro-tube treated with silane to render its inner surface hydrophobic. POPC liposome is then injected into the microtube. It is known that POPC lipid will form a monolayer to such a surface by orienting their hydrophobic tails toward the hydrophobic wall. The experimental results using a mode with similar sensitivity as the previous experiment are shown in Fig. 8.39. The resonance shift in this case is 22 pm, which is about half of that observed for the adsorption of a lipid bilayer. These two experiments suggest that the microtube resonator is capable of accurately determining an adsorbed biomolecular layer down to a few nm thicknesses. 

Munoz, S. Mallen, J. Nakano, A. Chen, Z. Gay, L Echegoyen, L. Gokel, G. W., (1993) Ultrathin monolayer lipid membranes from a new family of crown ether-based bola-amphiphiles J. Am. Chem. Soc. 115, 1705-1711. 

Figure 4.3 Vesicular monolayer lipid membranes (MLM) made of bolaamphiphiles with a charge on the inner surface are stable, because charged head groups cannot cross the hydrophobic membranes. Dissociation andfusion of MLMs are slow.

Covesicles of the cationic nitrobenzoate 6 and DODAC, or corresponding DPP-analogues, e.g. 7, are hydrolysed at pH 8. Nitrophenolate absorption appears at 400 nm. The outer benzoate esters at the outer vesicle surface are hydrolysed within minutes and the same head groups on the inner surface survive for 1-15 hours (Figure 4.9). Detailed kinetics of flip-flop dynamics and OH permeation have been evaluated in these systems. Monolayer lipid membranes made of macrocyclic bolaamphiphiles showed enhanced dynamic stability. ... 

Recent reports on monomeric and polymerized bolaamphiphiles1 provide evidence for their potential application in the broader field of molecular organizates (1,2). Thus monomeric bolaamphiphiles have been employed in the formation of monolayer lipid membranes or vesicles (1-3). formation of micelles (4-5) and also for spanning bilayer membranes (1-6) The latter process has resulted in the stabilization of membranes. 

The archaebacterial lipids have been used to prepare liposomes. They form monolayer lipid membranes70 rather than the normal bilayer type because there are polar groups on both ends of the a,oo-dicarboxylic acids. Membrane lipids extracted from these bacteria have also been used to form liposomes. Physical studies showed positive results such as extra stability at high temperature, at high or low pH, and in other harsh conditions.71-74... 

The bilayer lipid membrane (BLM) is typically 4-6 nm thick. Bolaam-phiphiles with a water-soluble headgroup on both ends of a hydrophobic core can form thinner monolayer lipid membranes (MLM). Membranes as thin as 1.5 nm have been obtained (Fig. 2.5.9). 

Figure 2.5.11 In monolayer lipid membranes the inner and outer headgroups are covalently connected to each other. In all investigated cases so far, the molar ratio of inner to outer head groups is 1 1. This indicates that no bending of the hydrophobic core occurs. Furthermore, fusion of charged vesicle membranes does not occur easily.

Figure 2.5.13 Model of a symmetrical monolayer lipid membrane with an asymmetrical distribution of counterions. The empty spaces for solutes are exclusively on the outer surface.

Fuhrhop, J.-H., Fiitsch, D. (1986). Bolaamphiphiles form ultrathin, porous, and unsym-metric monolayer lipid membranes, J. Am. Chem. Soc., 108 130. 

Langmuir-B lodged Lowest unoccupied molecular orbital Methyl(2,4-dinitrophenyl)aminopropanoate Monolayer lipid membrane... 

In order to elucidate the physicochemical properties of such a biological membrane interface, several model membrane systems (lipid monolayer, lipid bilayers, and protein-incorporated lipid model membrane systems) which mimic biological membrane interfaces have also been studied.In particular, many properties at the membrane surface are intimately related to the electrical potential originating from the fixed charge or electrical polarization of the membrane constitutents. 

XHE chemistry of Self-Assembled Monolayers—Lipids in Materials Science... 

THE CHEMISTRY OF... Self-Assembled Monolayers— Lipids In Materials Science and Bioengineering 1036... 

Figure 14 Structure of several bolaamphiphiles used in nanotube formation. At the bottom, model of the four possible types of monolayer lipid manbranes (MLMs) from unsymmetrical bolaamphiphiles is shown.

To check if for DOPC monolayers, lipids from the drop monolayer are also captured under the drop liquid, we did experiments where the drop monolayer was fluorescently labelled, see Fig. 8. From these experiments we observe that fluorescently labelled lipids are also submerged into the subphase. 

To conclude we can say that for drop impacts on DOPC monolayers, lipids from the drop and target monolayers are captured under the drop liquid pattern and extra-bright areas are formed at the back-side of the drop impact pattern with lipids from the target monolayer. 

From pictures taken in lateral perspective (results not shown), it can be observed that in the front part of the drop impact pattern, where the main mass of the drop liquid come to rest, the stable DPPC monolayer is broken and the drop liquid submerges into the target bulk liquid due to the density difference. This involves as well the drop and target monolayers lipids captured under the front part of the drop liquid. 

Staining Applications Axons bovine brain tissues mitral/tufted cells retinal ganglion cells bacteria cells lipid bilayers lipid monolayers lipid membranes lipoproteins liposomes membranes neurons neural tracers vessel peptides proteins antibodies ... 

Shah, D. O., and Schulman, J. H., 1967a, Influence of calcium, cholesterol, and unsaturation on lecithin monolayers, /. Lipid Res. 8 215. 

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