Motofusa Akiyama

This paper describes the synthesis and catalytic activities of stratiform protein microtube reactors containing a glucose oxidase (GOD) enzyme layer. The microtubes were fabricated by layer‐by‐layer assembly using a microporous polycarbonate membrane with human serum albumin (HSA), poly(l‐arginine) (PLA), and GOD. The GOD component was introduced into the tube wall as the innermost layer, the intermediate layer, or all internal protein layers. SEM observations revealed the formation of uniform hollow cylinders with ca. 1.17 μm outer diameter and ca. 135 nm wall thickness. In aqueous medium, each microtube catalyzed β‐d‐glucose oxidation with high efficiency. We first ascertained the enzyme parameters (K_m and k_cat) of these microtube reactors. Different catalytic activities that have dependent on the GOD layer position in the cylindrical wall have been elucidated.

This report describes the synthesis and structure of core–shell protein clusters comprising haemoglobin (Hb) at the centre and recombinant feline serum albumin (rFSA) at the exterior, named as haemoglobin–albumin clusters (Hb–rFSA₃). Specifically, we highlight their capability as an artificial O₂ carrier that can be used as a red blood cell (RBC) substitute for cats, the most populous pet animal in the world. First, rFSA was expressed by genetic engineering using Pichia yeast. The proteins show identical features to the native FSA derived from feline plasma. Single crystals of rFSA were prepared under a microgravity environment on the international space station (ISS), from which the structure was first revealed at 3.4 Å resolution. Subsequently, bovine Hb was wrapped covalently by rFSA using an α-succinimidyl-ε-maleimide crosslinker, yielding Hb–rFSA₃ clusters. Three rFSA entities enfolded the Hb nuclei satisfactorily, giving the protein clusters a negative surface net charge (pI = 4.7) and preventing an immunological response against anti-Hb antibodies. The O₂ affinity was higher (P₅₀ = 9 Torr) than that of the native Hb. The Hb–rFSA₃ clusters are anticipated for use as an alternative material for RBC transfusion, and as an O₂ therapeutic reagent that can be exploited in various veterinary medicine scenarios.

Human serum albumin (HSA) microtubes with an interior surface composed of Pt nanoparticles (PtNPs) are self‐propelled in aqueous H₂O₂ medium. They can capture cyanine dye and Escherichia coli (E. coli) efficiently. Microtubes were prepared by wet templating synthesis by using a track‐etched polycarbonate (PC) membrane with alternate filtrations of aqueous HSA, poly‐l‐arginine (PLA), and citrate‐PtNPs. Subsequent dissolution of the PC template yielded uniform hollow cylinders made of (PLA/HSA)₈PLA/PtNP stacking layers (1.16±0.02 μm outer diameter, ca. 23 μm length). In aqueous H₂O₂ media, the soft protein microtubes are self‐propelled by jetting O₂ bubbles from the open‐end terminus. The effects of H₂O₂ and surfactant concentrations on the velocity were investigated. The swimming microtube captured cyanine dye in the HSA component of the wall. Addition of an intermediate γ‐Fe₃O₄ layer allowed manipulation of the direction of movement of the tubule by using a magnetic field. Because the exterior surface is positively charged, the bubble‐propelled microtubes adsorbed E. coli with high efficiency. The removal ratio of E. coli by a single treatment reached 99 %.

We report the synthesis, structure, and influenza A virus trapping capability of protein nanotubes with an internal wall of fetuin glycoprotein. The nanotubes were fabricated via the alternating layer-by-layer assembly of human serum albumin (HSA), poly-l-arginine (PLA), and fetuin into a track-etched polycarbonate (PC) membrane (pore size, 800 nm), followed by dissolution of the PC template. In an aqueous medium, the (PLA/HSA)5PLA/fetuin nanotubes captured influenza A virus PR8 (H1N1) efficiently, as revealed by ELISA measurements. We report the synthesis, structure, and influenza virus trapping capability of protein nanotubes with an internal wall of fetuin glycoprotein. The nanotubes were fabricated via the layer-by-layer assembly of human serum albumin, poly-l-arginine, and fetuin into a track-etched polycarbonate membrane. In aqueous medium, the nanotubes captured influenza A virus PR8 (H1N1) efficiently as revealed by ELISA measurements.

There is no blood bank for pet animals. Consequently, veterinarians themselves must obtain “blood” for transfusion therapy. Among the blood components, serum albumin and red blood cells (RBCs) are particularly important to save lives. This paper reports the synthesis, structure, and properties of artificial blood for the exclusive use of dogs. First, recombinant canine serum albumin (rCSA) was produced using genetic engineering withPichiayeast. The proteins showed identical features to those of the native CSA derived from canine plasma. Furthermore, we ascertained the crystal structure of rCSA at 3.2 Å resolution. Pure rCSA can be used widely for numerous clinical and pharmaceutical applications. Second, hemoglobin wrapped covalently with rCSA, hemoglobin–albumin cluster (Hb-rCSA₃), was synthesized as an artificial O₂-carrier for the RBC substitute. This cluster possesses satisfactorily negative surface net charge (pI = 4.7), which supports enfolding of the Hb core by rCSA shells. The anti-CSA antibody recognized the rCSA exterior quantitatively. The O₂-binding affinity was high (P₅₀ = 9 Torr) compared to that of the native Hb. The Hb-rCSA₃cluster is anticipated for use as an alternative material for RBC transfusion, and as an O₂therapeutic reagent that can be exploited in various veterinary medicine situations.

The water-solubilisation of porphyrin derivatives is very important for biological applications. Although liposomal drug carriers for porphyrin derivatives have shown significant promise in the field of medicinal chemistry (e.g., as sensitisers for photodynamic therapy), it is currently not possible to prepare lipid-membrane-incorporated tetraphenylporphyrin (TPP) with a high concentration of TPP using conventional methods. In this study, we have succeeded in preparing lipid-membrane-incorporated TPP and zinc(II) tetraphenylporphyrin (ZnTPP) from the corresponding TPP or ZnTPP·cyclodextrin complex using the exchange method in lipid-membranes composed of liposomes. Furthermore, the exchange method allowed for the incorporation of TPP or ZnTPP into the plasma membranes of HeLa cells. However, it was not possible to prepare lipid-membrane-incorporated porphyrin derivatives with polar and hydrophilic groups in the meso positions using this exchange reaction.

Glc-pendant C ₆₀ compounds exhibited high photocytotoxicity against HeLa cells due to the more efficient singlet oxygen generation as compared with that of Glc-pendant azafulleroids.

The incorporation of neutral [70]fullerenes (C₇₀) led to bicelle formation in a relatively low lipid concentration range from neutral lipid mixtures (DMPC/DHPC). Furthermore, C₇₀ addition resulted in the formation of large bicelles with a radius of ca. 100 nm, in contrast to C₇₀-free bicelles that were formed from anionic lipid mixtures (DMPC/DHPC/DMPG). The stabilization of these bicelles was attributed to C₇₀ incorporation into the membranes.