A liposome has been applied to cosmetics field as a bio-membrane model and a vehicle of various products, especially skin care cosmetics. In this review, I introduce some experimental results related to an application of liposome technique to cosmetics.
In order to evaluate a safety of low materials and final products of cosmetics, liposomes are used as bio-membrane model instead of using some animals. The interaction between liposomes and some surfactants was studied and the results gave a good correlation with the known safety data. Moreover, liposomes comprised of stratum corneum lipids were examined as skin membrane models.
On the other hand, there are many reports concerning percutaneous penetration using liposomes as a drug-carrier. These report indicate that liposomes have an ability for improvement of an accumulation of drugs (or humectants) to the skin. That is, besides being a humectant, a liposome is a desirable drug-carrier for cosmetics.

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Liposomes are frequently used as model systems to clarify diverse functions of biomembranes. We have been introducing various functional polymer chains on the surface of liposomes by using a lipophilic radical initiator. In this review, our recent studies concerning specific molecular recognition on liposome surfaces were introduced.

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This mini-review focuses on the application of liposomes in two fundamental techniques of biotechnology, gene transfer and extraction of membrane proteins. Three major methods of gene transfer using liposomal carrier, namely, fusogenic HVJ-liposomes, fusogenic PEO-modified liposomes and pH-sensitive liposomes, are described together with cationic “liposomes” for transfection. For the membrane protein extraction, the background and the recent development of the technique are explained. In addition, recent reports of stimulation of T-cells with liposome-incorporated gangliosides and chaperone-like behavior of liposomes are briefly noted.

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Researches on application of membranes to biotechnology are described relating with the production of useful substances. First, the applications of solid membranes are described, such as reactions using solid membranes with hydrophobic substrates, with regeneration of coenzymes and those related to enantioselectivity. Also, application to the plant cell membrane bioreactors and the analysis of pressure swing operation of membrane bioreactors are discussed.
Liquid membranes are interesting with respect to its application to the reactions combined with selective separation. Concepts of liquid membranes have been extended to reversed micelles which can be applied to separation of biomaterials such as proteins, peptides and amino acids. Bioaffinity extraction in biocompatible systems is presented. Finally, the author introduced some of the recent topics on applications of reversed micelles such as extractive separation of DNA, protein refolding and molecular imprinting at the oil/water interface.

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Explicit formulae for estimating the thicknesses of distribution forms of the potential, field and charge density of a planar electric double layer at high Zeta potential are presented.According to the exact solution of a planar electric double layer adaptable to arbitrary Zeta potential, reported by Verway and Nissen [Phil. Mag. 28 (1939) 435], the distribution forms of the potential, field and charge density are mathematically complicated in contrast to the Debye-Hückel theory that is valid for low Zeta potential, where these distribution forms are purely exponential. Asymptotic properties of the exact solution at high Zeta potential reveal that the thicknesses defined by the distances between the flat interface and the positions at which 1/e of the peak values of the potential, field and charge density are located, obey explicit asymptotic formulae.

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Gas permeation properties of poly (1-trimethylsilyl-l-propynee) [PMSP] /poly (phenylacetylene) [PPA] blends are reported. As PPA content in these blends increases, gas permeability decreases, while gas separation factors and blend film density increase. For a pure PMSP film, the order of gas permeability coefficients is CO₂>CH₄≥H₂>O₂>N₂. However, for PMSP/PPA blend films, the permeability of CH₄ is lower than that of H₂. As a result, the ranking of gas permeabilities in PMSP/PPA blend films becomes CO₂>H₂>CH₄>O₂>N₂. Furthermore, the reduction in the ratio of blend permeability to PMSP permeability is greater for a larger penetrant than for a smaller penetrant. This reduction in blend-to-PMSP permeability ratio is smaller for PMSP/PPP blends than for the previously reported PMSP/ poly (1-phenyl-1-propyne) [PPP] blends at the same PPA and PPP contents.

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To develop a new type of quick-drying nail enamel, we took a different approach by modifying the polymer resin rather than using fast evaporating organic solvent. This was accomplished by grafting silicone chains into the structure of hydrophobic acrylic polymer to create a novel graft polymer which formed non-tacky film. The film retains less high polar solvents upon drying and allows rapid vapor transmission. In nail enamel applications, the superior properties of the graft polymer make it possible to formulate excellent nail enamel which are quick-drying, long lasting, safe and comfortable to use.

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