Sumio Aisawa

CELLULAR UPTAKE BEHAVIOR OF FLUORESCEIN: INTERCALATED LAYERED DOUBLE HYDROXIDE

In order to define the ability of layered double hydroxide (LDH) as materials for drug delivery, fluorescein (Fluo) anion intercalated LDH (Fluo/LDH) was synthesized by hydrothermal treatment and observed the cellular uptake of the Fluo/LDH for mammalian cell (L929). The synthesized Fluo/LDH showed a LDH structure, high fluorescence and low cytotoxicity. According to the fluorescence, confocal and TEM images of cells, the Fluo/LDH seemed to be internalized into the L929 cell by cellular endocytosis and dissolved inside the cell to exhibit the fluorescence of cellular cytoplasm.

Intracellular release of fluorescein anion from layered double hydroxide nanoparticles indicating endosomal escape

In recent years, layered double hydroxide (LDH) has been attempted to be applied to a molecular container due to their anion exchange ability, low cytotoxicity and good biocompatibility. In this paper, we investigated the intracellular behaviour of LDH particles in mammalian cells after internalization. Nanoparticles of fluorescein (Fluo) intercalated LDH, Fluo/LDH, were prepared by the coprecipitation followed by subsequent hydrothermal treatment. As-prepared Fluo/LDH particles have the LDH structure and morphology of hexagonal sheet of 100 nm on the average. In addition, Fluo/LDH also exhibited high green fluorescence and low cytotoxicity. By a confocal laser scanning microscopy, the dim green fluorescence was observed throughout cells, including the nucleus. This result indicated that Fluo/LDH released guest anion (Fluo) from LDH structure inside cells. Furthermore, because the fluorescence was observed throughout the cell, Fluo was not retained within endosome structure, i.e., Fluo/LDH was dissolved to release Fluo from endosome.

Long period preservation of marine products using electrostatic field

The effect of an AC electric field on the freshness of marine products was experimentally investigated. An AC voltage of 10 kV with 50 Hz in frequency was generated with a transformer and applied to a plane electrode set in an incubator. The biological material was the gonad of purple sea urchin. The AC electric field with 50 Hz in frequency was applied to the gonad at −1 °C for 7 days. Freshness was evaluated by measuring protein release and lactate dehydrogenase (LDH) activity. The results showed that the protein release and LDH activity in the gonad were suppressed by applying the AC electric field, compared with that without the AC electric field. Moreover, the gonad was treated with the AC electric field at −5 °C for 3 days and then preserved at 0 °C for 1 day without the field. This electrical field treatment of the gonad prolonged the freshness date for more than 10 days under 4 °C preservation condition. In addition, the permeability of the cell membrane was suppressed by applying the AC electric field. Concerning the relationship between permeability and AC electric field, the conformational change of bovine serum albumin (BSA) induced by the AC electric field was evaluated on the basis of UV absorption spectra. The results revealed that the secondary and/or higher-order structure gradually changes with preservation period. The conformational change of the BSA molecule was induced by applying the AC electric field.

Production of Charcoal with High Adsorptive Activity from Waste Plywood Panel for Concrete Form

A large quantity of waste plywood panel for concrete form has recently been generated with progress of construction industry and its effective utilization become a social urgent problem. In this study, the production of charcoal from the waste plywood form and its adsorption characteristics were investigated. The virgin plywood form and the raw plywood material were also examined for reference. The plywood samples was first pulverized as a chip and carbonized at 500-1, 000°C under nitrogen atmosphere using an electric furnace. The yield of the charcoal was slightly decreased with increasing carbonization temperature, being about 30% at 800°C in the same manner as ordinary charcoals. The specific surface area of the charcoal was increased remarkably at the temperature range over 800°C. X-ray diffraction analysis reveals that the partial graphitization proceeded at carbonization temperature range over 800°C, particularly in the case of the waste plywood form. In the experiments of adsorption in aqueous solutions, the charcoal from the waste plywood form was found to have 3-5 times activity in the adsorption of alkaline dye (methylene blue) and acidic dye (orange II) compared to that from the raw plywood material and about 15 times activity in the adsorption of bisphenol A which is one of endocrine disruptors. Chemical analysis shows that the content of metal ions such as Ca2+, Na+, K+, Al3+ and Total-Fe was considerably larger in the charcoal from the waste plywood form than in that from the virgin plywood form and the raw plywood material. Therefore, the partial graphitization of the charcoal assumed to be accelerated by the catalytic action of the metal ions derived from concrete, which leads to the remarkable increase in the hydrophobicity of the charcoal surface, viz, in the adsoptive activity for organic compounds. It was concluded that the charcoal with high adsoptive activity could be produced from the waste plywood form without any additional activation procedures.