Langmuir-Blodgett membranes

Diacetylenes like [30o] after being laboriously prepared, are not polymerized either by heat or ultraviolet irradiation (Iwamura, 1990). Control of molecular packing in crystals is now needed. Introduction of the technology of liquid crystals or Langmuir-Blodgett membranes (Hupfer et al., 1981 Koch and Ringsdorf, 1981) may be of help. 

Erbach R., Vogel A., and Hoffinann B. 1992. Ion-sensitive field-effect structures with Langmuir-Blodgett membranes. In F. Scheller, R.D. Schmid (eds). Biosensors Fundamentals, Technologies, and Applications, GBF Monograph 17, pp. 353-357, New York, VCH PubUshers. 

FIGURE 1.8 Langmuir-Blodgett membrane (four molecular layers). 

Erbach R, Hoffmann B, Schaub M and Wegner G (1992) Application of rod-like polymers with ionophores as Langmuir-Blodgett membranes for Si-based ion sensors. Sens Actuators B-Chem 6 211-216. 

In the field of biomimetic chemistry, phospholipid molecules have been utilized for the preparation of cell membrane-like stractures, namely, liposomes and Langmuir-Blodgett membranes. However, a major disadvantage of molecular assemblies of this kind is their inadequate chemical and/or physical stability. Stabilization of the phospholipid assembly is therefore an important topic of focus in the construction of interfaces between living and artificial systems. One approach to addressing this issue is the design of a new type of polymer system with PC groups. 

Raitman, O.A., Selector, S.L and Arslanov, V.V. (2006) A novel ultra-sensing composed Langmuir Blodgett membrane for selective caldum determination in aqueous solutions. Sensors and Actuators. 

Petrov, J. G. Mobius, D. Interfacial acid-base equilibrium and electrostatic potentials of model Langmuir-Blodgett membranes in contact with phosphate buffer. Colloids Surf., A 2000, 171, 207-215. 

Langmuir-Blodgett films (LB) and self assembled monolayers (SAM) deposited on metal surfaces have been studied by SERS spectroscopy in several investigations. For example, mono- and bilayers of phospholipids and cholesterol deposited on a rutile prism with a silver coating have been analyzed in contact with water. The study showed that in these models of biological membranes the second layer modified the fluidity of the first monolayer, and revealed the conformation of the polar head close to the silver [4.300]. 

A similar approach is the use of insulating Langmuir-Blodgett films of phospholipid membranes on electrodes that can be opened by ions ° Electroactive... 

FIG. 1 Geometries of electrolyte interfaces, (a) A planar electrode immersed in a solution with ions, and with the ion distrihution in the double layer, (b) Particles with permanent charges or adsorbed surface charges, (c) A porous electrode or membrane with internal structures, (d) A polyelectrolyte with flexible and dynamic structure in solution, (e) Organized amphophilic molecules, e.g., Langmuir-Blodgett film and microemulsion, (f) Organized polyelectrolytes with internal structures, e.g., membranes and vesicles. 

The very popular applications of the adsorption potential measurements are those dealing with the surface potential changes at the water-air and water-hydrocarbon interfaces when a monolayer film is formed by an adsorbed substance. Phospholipid mono-layers, for instance, formed at such interfaces have been extensively used to study the surface properties of the monolayers, which are expected to represent, to some extent, the surface properties of bilayers, and biological, as well as various artificial membranes. An interest in a number of applications of the ordered thin organic films, e.g., Langmuir-Blodgett layers, dominated the insoluble monolayer research activity during the last decade. 

Construction of well organized functional Langmuir-Blodgett films by mimicking structures and functions of biological membranes... 

RET in two dimensions has been studied in monolayers, Langmuir-Blodgett films and phospholipid bilayers of vesides. In particular, RET provides a very useful tool for the investigation of biological membranes, as exemplified in Box 9.2. 

Wolfbeis et al. [105-107] developed several fluorimetric flow-through sensors based on a sensing microzone consisting of a multilayer lipid membrane formed on a glass support by using the Langmuir-Blodgett (LB)... 

Figure 5.25 — Flow-through ion-selective optrode based on a multilayer lipidic membrane prepared by the Langmuir-Blodgett method. (A) Cross-sectional view of the composite six-layer membrane (four layers of arachidic acid/ valinomycin covered by an arachidic acid and rhodamine dye bilayer). (B) Optical arrangement integrated with the sensor, which is connected to a flow system. LS light source Ml and M2 excitation and emission monochromator, respectively FI and F2 primary filters M mirror LB lipid-sensitive membrane in a glass platelet FC flow-cell A amplifier D display P peristaltic pump. (Reproduced from [107] with permission of the Royal Society of Chemistry).

Surfactants provide several types of well-organized self-assembhes, which can be used to control the physical parameters of synthesized nanoparticles, such as size, geometry and stability within liquid media. Estabhshed surfactant assembles that are commonly employed for nanoparticie fabrication are aqueous micelles, reversed micelles, microemulsions, vesicles [15,16], polymerized vesicles, monolayers, deposited organized multilayers (Langmuir-Blodgett (LB) films) [17,18] and bilayer Upid membranes [19](Fig. 2). 

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