X-ray reflectivity is a non-destructive characterization technique for thin films. Either solids or liquids, inorganic or organic compounds can be analyzed. Although this technique has the disadvantages that relatively wide and flat samples are necessary, they are overcome by using synchrotron radiation sources. In this article, characterization of protein layers bound to supported lipid bilayers and time-resolved measurements for protein layers formed on a water surface are shown for examples.

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To clarify structure-function relationships of membrane protein assemblies, experimental platforms suitable for them are required. In photosynthetic bacteria, light-harvesting complex 2 (LH2) and light harvesting/reaction center core complex (LH1-RC) play the key roles of capturing and transferring light energy and subsequent charge separation. These photosynthetic apparatuses form a supramolecular assembly in the photosynthetic membrane; however, how the assembly influences the efficiency of energy conversion is not yet clear. Here, we describe our recent works addressing evaluation of structure-function relationship of the supramolecular assembly of the photosynthetic antenna complexes in various lipid bilayer systems.

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Atomic force microscopy (AFM) is a powerful technique for probing local mechanical properties of single cells, which are related to their cytoskeletal structures. To quantify the rheological properties of single cells, we developed AFM techniques combined with micro-fabricated substrates. Studies revealed the statistical feature of complex shear modulus of single cells depending on their cytoskeletal structures, according to a power-law rheology model. Moreover, we investigated how the force exerted at the focal adhesion propagated through cytoskeletal networks between focal adhesions on cell surfaces. The results showed that force through cytoskeletal networks propagated as an elastic manner while the cells exhibited the power-law rheology around the focal adhesions. These studies demonstrate that AFM allows us to explore the mechanical properties of complex materials composed of lipids and proteins such as cytoskeleton in live cells.

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To overcome difficulties of conventional fusion with fluorescent/luminescent proteins, post-translational labeling methods using pairs of small genetically-encodable ‘tags’ and synthetic ‘probes’ targeting the tags have been widely studied in recent years. We have developed a quick tag-probe labeling method using a high-affinity heterodimeric coiled-coil formation between the E3 tag (EIAALEK)₃ attached to the target protein and the Kn probe (KIAALKE)_n (n = 3 or 4) labeled with a fluorophore. The labeling is cell-surface-specific and completed within 1 min, therefore suitable for monitoring oligomerization/internalization of membrane proteins on living cell surface. Taking advantage of easiness in multicolor labeling, the degree of internalization of the β₂ adrenergic receptors following agonist stimulation was evaluated by ratiometric detection of pH decrease in endosomes.

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The ATP-binding cassette protein A1 (ABCA1) mediates the secretion of cellular cholesterol and phospholipids to apolipoprotein A-I (apoA-I) to form high-density lipoprotein (HDL). By using cellbiological approaches and several mutants, we showed that ABCA1 functions as “apoA-I receptor” and “lipid transporter” and both functions are necessary to the HDL formation. From these results, we proposed a novel HDL formation model.

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A transdermal drug delivery system (TDDS) has attracted much attention due to several advantages over the other administration routes such as injection from the viewpoint of a less harmful method and avoiding first pass through liver. However, its real drug application has been limited to small or lipophilic drugs that can be permeated through the stratum corneum, which has a strong barrier function. Here, we focused on Solid-in-Oil-in-Water (S/O/W) emulsions as a novel TDDS carrier. This technique can encapsulate large hydrophilic molecules such as oligopeptides, proteins and DNAs in the inner oil phase of Oil-in-Water (O/W) emulsion by coating the hydrophilic macromolecules with surfactant molecules. Dispersing hydrophilic macromolecular drugs into the oil phase, S/O/W emulsion containing the hydrophilic drugs can raise the affinity and distribute to the hydrophobic stratum corneum. In this study, we encapsulated hydrophilic macromolecules into S/O/W and investigated the penetration behavior of hydrophilic macromolecules through the skin.

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Microwave heating was applied for the synthesis of faujasite zeolite membranes. Dense zeolite layers with very low Si/Al ratio ( = ∼1.1) were formed on the seeded α- Al₂O₃ supports in a shorter synthesis time than the conventional method. Membranes showed high dehydration performance in the pervaporation of H₂O/ethanol (α= 387, Flux = 2.67 kg m^-2 h^-1 ) and H₂O/i-propanol (α= 2300, Flux = 3.53 kg m^-2 h^-1 ).

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Kurita's brand new slime control agent “KURIVERTE® IK-110” has the characteristic effect called “Peel off ability”. This chemical can remove the bio-fouling on the RO membrane without stopping the operation of the plant. The actual plant data shows the effect of IK-110, improving the Flux and ΔPressure with only dosing it before the RO membrane in operation. And regarding to the safety to human body, it's safer than conventional biocide like isothiazolin. IK-110 got the certification of NSF in 2011 as the first slime control agent can be dosed to RO membrane in operation.

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