Inorganic fluorescent materials are excellent in monochromaticity and durability. Therefore, they are expected to be used as bioprobes. In this study, biocompatible and pH-responsive fluorescent inorganic nanorods were fabricated by modification of the surface of europium hydroxide nanorods (ENRs) with hydroxyapatite (HAp). One method to deposit HAp on ENR surfaces was that using immersion in simulated body fluids (SBFs) and the other was that using alternate soaking process (ASP). In the method using SBFs, HAp deposition was observed but they did not fully cover the surface of ENR. On the other hand, the surface of ENR was covered with HAp entirely, and the coating amount depended on the number of cycles of ASP. Furthermore, the adsorption of proteins such as fluorescein-loaded bovine serum albumin and cytochrome C on HAp-modified ENR was confirmed. The release behavior of these protein changed depending on the isoelectric point of the protein and the pH of the solution. The present results indicate potential application of these HAp-modified ENRs as a fluorescent, pH-responsive drug carrier.

A huge collection of 4390 dye compounds is preserved and exhibited in the Alumni Memorial Hall at the Faculty of Science and Technology, Gunma University. This valuable collection of dye samples is the largest in the world.

In 2023, this collection was confirmed as Chemical Heritage #062 by the Chemical Society of Japan. Most dyes were imported from Germany and are well preserved until now.

In this article, the origin, reason, and construction of this collection is described.

LUNATONE, which is a polyester core-shell toner with a large amount of crystalline polyester encapsulated and highly dispersed, achieved ultra-low-temperature fusing below 100℃ and significantly reduced toner consumption. As a result, we succeeded in reducing CO₂ emissions from toner used during printing by more than 40％ compared to conventional methods. Furthermore, by making it possible to fix at temperatures below 100℃, it has become possible to print not only on paper but also on soft films used for labels and packages.

Modulation spectroscopies for the characterization of the electronic transport properties of organic solar cells under operation are described. The electronic transport properties (electron and hole drift mobilites and bimolecular recombination constants) of organic solar cells are determined using modulated photocurrent and modulated photovoltage spectroscopies. These spectroscopic measurements were carried out in a prototypical organic solar cells with pol(3-hexylthiophene-2,5-diyl) (P3HT) : [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) bulk heterojunction. The transport properties are essential for the understanding of operation mechanisms in organic solar cells and for the improvement of the photovoltaic properties. In addition, the accumulation of the electronic transport properties obtained from the spectroscopic measurements in a variety of organic solar cells would be useful for the material design for high-efficiency organic solar cells.

Due to their solution-processability and lightweight, flexible, and semi-transparent properties, organic photovoltaics have been attracting much attention as a next-generation photovoltaic technology. Here, I will show the development of semiconducting polymers in our group and future prospects. In particular, I will focus on the control of crystallinity and molecular orientation of semiconducting polymers, which play crucial roles in improving the power conversion efficiency.