It is important to control intracellular trafficking of genes as well as drugs for developing a new drug delivery system. Plasma membrane and endosomal membrane are considered to be strong barriers for hydrophilic, high molecular weight compounds such as DNA. Virus are sophisticated gene delivery carriers which can overcome these barriers using specific peptides to bind cell surface receptors or to fuse with plasma or endosomal membranes. In this review, we will focus on the interaction between these biomembranes and virus peptides as well as recently synthesized fusogenic peptides to utilize them for developing a new delivery system.

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Basic peptides such derived from HIV-1 Tat and Drosophila Antennapedia proteins have been utilized as novel carriers for the intracellular delivery of various biopolymers. We have elucidated that these features were shared by many other arginine-rich peptides including various RNA- and DNA-binding peptides, and the presence of a ubiquitous internalization mechanism for the arginine-rich peptides has been suggested. In this review, the potential of the membrane-permeable arginine-rich peptides for the delivery of biopolymers into living cells is reviewed.

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Peptaibols are a family of peptides which have a high fractional content of an α, α-dimethyl amino acid, α-aminoisobutyric acid (Aib), and which have an α-amino alcohol at the C-terminus. Peptaibol forms voltage gated ion channels in bilayer lipid membranes. Since, the movement of ions through membrane-spanning channel proteins is fundamental to a number of physiological processes, it is valuable to investigate the properties of peptaibol ion channels which resemble in the motif of pore structures with biological ion channels. Development of the techniques related to structure elucidation and synthesis of peptaibols allow us to examine the relationships between peptaibol structure and its channel properties more easily by using its synthetic derivatives. In this article focus is on the context of current development of structure elucidation, synthesis and studies of structure-activity relationships of peptaibols and their derivatives.

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Hydrophobic lipid bilayer environment constrains transmembrane proteins mostly into an α-helical bundle structure. The folding processes of α-helical transmembrane proteins can be understood in terms of two energetically distinct stages, i.e. 1) independently stable transmembrane helices are formed and 2) the helices interact with each other to give a functional protein. The simplicity of the folding process enables us to use model transmembrane helices for elucidating driving forces working in membrane protein folding in the context of helix-helix interactions. Recent studies have devised several appropriate model peptides that form stable transmembrane helices and just started to quantitatively measure the helix-helix interactions in lipid bilayers. Possible driving forces involved in helix-helix and helix-lipid interactions are summarized. Statistical analyses of structure-known membrane proteins indicate diverse driving forces including the leucine zipper, the GlyXXXGly motif, network of hydrogen bonds and salt bridge.Furthermore, the lipid bilayer environment, which consists of diverse lipid species with asymmetric distributions in inner and outer leaflets, should have substantial effects on helix-helix interactions, therefore on the conformations of the whole proteins.

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Ceramic membranes have gained much interest for use in the pervaporation process due to their high chemical resistance and good thermal stability. Silica is one of the most attractive materials for inorganic membranes because of its good chemical stability against acid, low cost of the its precursor and its ability to be shaped into a thin microporous film. Silica membranes supported on porous alumina were prepared by the sol-gel method using colloidal and polymeric sols. The effect of the sol composition on the microstructure and performance of the membranes were studied, and a strategy to improve the selectivity of the membrane was explored. From characterization of these membranes by SEM and AFM, it was found that the sol composition played a significant role in the membrane performance due to their different sizes. Data from a pervaporation measurement for the dehydration of acetic acid indicated that a multi-layer coating using sols with different compositions was effective for improving the selectivity of the membrane. The membrane pore sizes estimated from a pervaporation measurement of a pure liquid substance with known molecular diameters are reported.

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The metal coated hollow fiber membrane (MCH) has been applied as a working electrode of an electrochemical detector for high performance liquid chromatography (HPLC). In this paper, the improvements of the sensitivity of the copper coated hollow fiber membrane (Cu-MCH) electrode as a sensor for carbohydrates were described. The MCH electrode had the tubular structure. Therefore, there was a problem of decreasing the output signal by dilution of analysis with the dependence on the inside volume. In order to reduce the inside volume, the plug put inside of the MCH and a thinner hollow fiber membrane were used. The plug was effective to make the MCH electrode sensitive resulting the detection limit (S/N=3) of glucose lowered from 1.7 pmol to 0.95 pmol. The hollow fiber membrane in which inside diameter was thinner was also effective. The detection limit dropped from 1.7 pmol to 0.56 pmol, when it was changed to 0.6 mm from 1.0 mm. In addition, it was effective to decrease the noise current when the hollow fiber membrane of 0.6 mm inside diameter was covered with the copper on the gold (Cu/Au-MCH).The detection limit was improved to 0.24 pmol. The simultaneous detection of sorbitol, glucose, fructose, lactose, saccharose, raffinose and maltose was demonstrated with the Cu/Au-MCH in HPLC. The detection limits were 0.39, 0.24, 0.39, 0.38, 0.58, 0.53 and 0.82 pmol, respectively.

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In the process of semiconductors, heavy metal ions and TMA (Trimethyl amin) cause defects of the products. So the reduction of these cations in ultra-pure water (UPW) is desired. We developed Ion Adsorption Membrane (MICROZA SKT-352F), which can reduce the heavy metals in UPW less than 0.1ppt.

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