In recent years, new thermal insulation materials with lower thermal conductivity and lightweight have been fabricated. However, due to the problems such as heat resistance, their practical use is limited to only below 1000°C. In this paper, the thermal insulation performance of fibrous fumed alumina compacts was evaluated by repeatedly measuring the thermal conductivity at temperatures up to 1200°C. As a result, it revealed that the compacts have low thermal conductivity of 0.040–0.065 W/(m·K) between 200°C and 1000°C. After receiving the heat processing up to 1200°C, its thermal conductivity rapidly increased. However, it was less than half of that of existing ceramic fiber insulation. The compressive strength and flexural strength also increased by the repeated heat processing. The increase of thermal conductivity by the repeated heat processing was explained by the increase of solid thermal flux due to the sintering of particles in the compact and the increase in thermal radiation flux due to the surface oxidation of SiC particles.

In this paper, we introduced the fabrication of β-TCP/Ti composites as biomaterials by the spark plasma sintering (SPS) method, and two studies to customize powders for the metal-ceramic composite (MCC) fabrication using SPS. In the study attempting the fabrication of β-TCP/Ti composite by SPS, the difficulty of metal-ceramics sintering was revealed; the decomposition of β-TCP due to the reaction with Ti particles during sintering decreased in sinterability. Thus, based on the simple strategy of “reducing the contact area between Ti particles and β-TCP particles to suppress the decomposition of β-TCP during sintering”, we attempted to solve the problem by customizing powders for the composite with two different powder preparation methods: the homogeneous precipitation method to control the agglomerate size of β-TCP, and the mechanical milling method to prepare Ti-Mg powder.

The microstructure of scaffolds is a critical factor for tissue regeneration. To clarify the effects of scaffold microstructure on tissue regeneration, scaffolds with the same properties except a specific parameter are necessary. Honeycomb scaffolds are considered proper for understanding of the microstructure effects due to the ordered architecture. In this context, our group demonstrated the effects of scaffold microstructure, such as the direction and size of channels and the porosity and size of micropores and nanopores, on tissue regeneration by in vivo evaluations using honeycomb scaffolds. Based on the findings, furthermore, we have optimized the microstructure of honeycomb scaffolds depending on applications. Here, I describe the microstructure effects of honeycomb scaffolds on angiogenesis and bone regeneration and the applications of the honeycomb scaffolds with controlled microstructure to orthopedic and dental fields.

In vivo imaging technology can detect and diagnose a total of transplanted stem cells remains unestablished. In order to enhance the safety and treatment effect of regenerative medicine, it is necessary to understand where transplanted stem cells accumulate in the tissue and how accumulated cells behave in the tissue at a single cell level. In this report, I mainly introduced the innovative diagnosis of transplanted stem cells in mice model by quantum dots (QDs) fluorescence imaging and whole tissue clearing technologies. Moreover, I shared with you about the quantum dots with super low-cytotoxicity, which were recently developed.

Messenger RNA (mRNA) therapeutics attracts growing attention, especially after approval of two vaccine formulations for coronavirus disease 2019 (COVID-19). Meanwhile, further advances in platform technologies are still demanded for widespread clinical application of mRNA. mRNA should be delivered to target tissues in its intact form, with its immunogenicity properly controlled depending on the purposes. This review addresses strategies to tackle this issue, including the development of biocompatible polyplex micelles and mRNA architectonics for improving mRNA nuclease stability, a polymer-based approach to inhibit liver sinusoidal clearance of nanoparticles, and incorporation of immunostimulatory adjuvancy to mRNA for vaccination.