Lipid semiconductor structures

In the perpendicular direction, there may be conduction along the polar end group or by change transfer between the hydrocarbon chains. Proton conductivity is also a possibility. No gas evaluation and no increase in resistance from polarization effects were noted, however, in our preliminary experiments. Recently we have started some studies on electrolyte-lipid semiconductor structures. We observed, for example, interesting differences in the effect of divalent ions on different lipid mono-layers (55). 

Self-assembled monolayers have recently attracted much attention as a new methodology for molecular assembly [249, 342]. They enable highly organized chemical binding of molecules of interest to the surfaces of, e.g., metals, semiconductors, and insulators. The well-ordered structure of self-assembled monolayers is in sharp contrast with conventional Langmuir-Blodgett films and lipid bilayer membranes in terms of stability, uniformity, and manipulation. Functional molecules can be arranged unidirectionally at the molecular level on substrates when substituents which will self-assemble on the substrates are attached to a terminal of the molecules. The wide variety of examples reported to date include porphyrins and metalloporphyrins in self-assembled monolayers [299-339]. 

Electrochemical impedance spectroscopy provides a sensitive means for characterizing the structure and electrical properties of the surface-bound membranes. The results from impedance analysis are consistent with a single biomembrane-mimetic structure being assembled on metal and semiconductor electrode surfaces. The structures formed by detergent dialysis may consist of a hydrophobic alkyl layer as one leaflet of a bilayer and the lipid deposited by dialysis as the other. Proteins surrounded by a bound lipid layer may simultaneously incorporate into pores in the alkylsilane layer by hydrophobic interactions during deposition of the lipid layer. This model is further supported by the composition of the surface-bound membranes and by Fourier transform infrared analyses (9). 

Development of Structurally Organized Photocatalytic Systems for Photocatalytic Hydrogen Evolution on the Basis of Lipid Vesicles with Semiconductor Nanoparticles Fixed on Lipid Membranes... 

A more elegant way to combine the advantages of PhCs on the basis of dispersed semiconductors with those of membrane-structured systems seems to be the inclusion of semiconductor nanoparticles into microscopic vesicular systems with bilayer lipid membranes (vesicles are the microscopic bubbles, see Section II and Fig. 4). It is anticipated that semiconductor nanoparticles in such systems can serve the role of very efficient and stable integral photoreaction centers mimicking completely the spatially well-organized... 

The purpose of this paper is to consider some experience in the field of engineering of composite structurally organized microheterogeneous systems based on lipid vesicles with semiconductor nanoparticles as photocatalysts. 

Deposition of insoluble monolayer of the dye by the Langmuir-Blodgett technique has also been studied as means of assuring close contact of the chromophore and the semiconductor. For example, Arden and Fromherz prepared a thin film electrode by evaporation of indium-tin-oxide and covered it with a bilayer of a lipid containing a cyanine dye in direct contact with the electrode [36,37]. Quantum yield for the transfer of electrons from the excited chromophore in the membrane structure to the semiconductor was found to be quite high (O.S).Based on the fluorescence lifetime of the dye in solution (= 3ns) and the quantum yield of the emission in the lipid bilayer, the electron transfer rate from the singlet excited state has been estimated to be =10lO s. ... 

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