Nucleic acids, serving as both a repository for genetic information and the basis for biological activity, can be regarded as highly ordered functional molecules. Oligonucleotides (ONs) are oligomers of nucleic acids that can now be obtained by chemical synthesis. The ONs thus obtained have been approved as nucleic acid therapeutics for the treatment of various diseases. Importantly, chemically modified non-natural ONs with augmented functionality are useful when the functions of natural ONs fall short of achieving therapeutic efficacy. Chemical modification of ONs can also facilitate their complexation with other functional materials and further enhance the functionality of the resulting hybrid materials. Examples of such modifications include the combination of ONs with small molecular compounds, peptides, proteins, or highly ordered nanostructures with enhanced biological stability as building blocks for self-assembly. Thus, strategies for the precise chemical synthesis of ONs will play an important role in the sustained progress of biomedical materials.

Polyclonal metastasis, which arises from clusters of circulating tumor cells, promotes metastasis development and has become a major target of metastasis inhibition. Mouse experiments have clearly verified that nonmetastatic and metastatic tumors coexist and form metastatic nests, but the detailed mechanism of extravasation remains unclear. We established a three-dimensional tumor microvessel model to investigate extravasation between nonmetastatic tumors, metastatic tumors, and mosaic tumor organoids in a mixed state by time-lapse imaging and to determine the sequential steps of the extravasation of tumor cells via vascular remodeling. This comparison revealed a new concept of extravascular invasion via vascular remodeling in metastatic carcinoma. Furthermore, the involvement of liver host cells, the hepatic stellate cells, demonstrated an interaction with metastatic cells to facilitate metastatic foci formation. Moreover, Adam28 was highly expressed exclusively in metastatic tumor cells, suggesting its involvement in vascular remodeling. These results demonstrate the ability of metastatic tumor cells for extravasation in polyclonal metastasis, which may lead to the development of new therapeutic targets.

In recent years, there has been an increasing demand for milky-white tooth color, prompting research. We devised a new method for preventing tooth staining caused by beverages by using cyclodextrin (CD) as a food additive. CDs are cyclic oligosaccharides consisting of several molecules of glucose linked by α-1,4 bonds. The coloring component of beverages, polyphenols, are incorporated into the cavities of the CDs to form a stable CD-polyphenol complex. In this study, to prevent tooth surface staining caused by various beverages, CDs (specifically α-CD, β-CD, and γ-CD (CDs)) were added to the beverages, which were then applied to hydroxyapatite (HA) discs and the coloration was examined. CDs added to black tea inhibited the tea-induced staining of the HA discs. In particular, β- and γ-CD prevented staining of the HA discs. Furthermore, due to its high water solubility, γ-CD effectively inhibited staining at higher concentrations. γ-CD inhibited staining not only by black tea, but also by various beverages, but the extent of the effect differed among beverages. This study suggests that γ-CD prevents tooth staining because of its ability to incorporate polyphenols.

Nanoparticles (NPs) exhibit different functions to larger particles because of their specific surface areas. Ultrasmall NPs (particle size < 10 nm) could exhibit novel functions because they are even smaller. This study aimed to evaluate the effect of ultrasmall silver NPs on RAW264 cells using cell viability assay, scanning electron microscopy, and transmission electron microscopy. Silver NPs with particle sizes of 8.2 and 34.8 nm were evaluated, and cells were exposed to these NPs at three different concentrations (25, 50, or 100 µg/mL). A clear decrease in cell viability compared with the control group was observed with 8.2 nm NPs at 100 µg/mL. The cell viability did not decrease in the other groups. No morphological differences were observed among the groups by scanning electron microscopy. In transmission electron microscopy,various morphological change were observed for the cells exposed to NPs. Further research using different biological assays is required to elucidate the effect of the ultrasmall NPs at a high concentration on cell viability.

This study was conducted to observe the dentin tubule sealing and biocompatibility of a newly developed dental hypersensitivity control material. The Fourth Dentin^® (4D) made mainly from nano-sized calcium carbonate was applied to bovine anterior dentin and observed vertically using a scanning electron microscope. Because 4D forms film on dentin and 4D vertically seals dentin tubules, human periodontal ligament fibroblasts, human deciduous dental pulp-derived fibroblasts, and human osteoblasts were cultured with medium-added 4D. As a result, the cell proliferative ability of each cell to which 4D was added was enhanced. Each cell was also reacted with 4D and the condition of the cells around 4D was observed. The results showed that 4D enhanced mitochondrial activity in human periodontal ligament fibroblasts, human deciduous dental pulp fibroblasts, and human osteoblasts, and that each of these cells proliferated around 4D, suggesting a biocompatibility between these cells and 4D.

Lipopolysaccharide (LPS) is a potential inducer of chronic inflammation, cellular senescence, and impaired bone regeneration. LPS sustained-release gelatin (LS-G), developed in our previous studies, is a useful chronic inflammation-inducing device; the application of LS-G has the potential to freely induce and regulate inflammation and cellular senescence in animal models via the sustained release of LPS and may be useful in elucidating pathological mechanisms. However, there is a paucity of information on the effects of conditions such as LPS concentration and the number of dehydrothermal treatments (DHT) on LS-G. Here, we investigated the effect of adjusting the number of DHT (1vh, 2vh) and concentration of LPS (×1, ×6, ×10, ×100) on the LS-G properties. First, we showed that implantation of LS-G with high LPS concentration can induce chronic inflammation in vivo. Next, we compared the LS-Gs under each condition for the properties, such as the micro-structure, water absorption time, and the LPS release behavior. The microstructure of the LS-G surface showed a few changes depending on the concentration of LPS or the number of DHT. The water absorption time significantly increased with the number of DHT. The LPS concentration was found to be related to the release of LPS. These results suggest that regulation of the number of DHT and the concentration of LPS may be useful for modulating the properties of LS-G. This study may lead to the development of highly functionalized LS-G that contribute to the development of an efficient model of chronic inflammation, cellular senescence, and impaired bone regeneration.

Dental materials that exhibit analgesic and sedative actions, including eugenol, have been frequently used for the treatment of oral hard and soft tissues. Various studies examined the toxicity of eugenol. However, in the field of dentistry, it is mixed with zinc oxide for hardening, and changes in the cell viability level in a mixed state of zinc oxide and eugenol remain to be clarified. In addition, in nanomaterials, the surface area per volume markedly increases, and cytotoxicity may be potentiated. We investigated cell viability after exposure to a mixture of nano zinc oxide and eugenol using the MTT method. As a result, cytotoxicity in the eugenol-mixed state increased with an increase in the concentration of nano zinc oxide. Furthermore, no difference was observed in the IC50 value of eugenol. In addition, there was no synergistic effect or reduction of cytotoxicity under the nano zinc oxide/eugenol-mixed condition. In the future, various dental materials containing nanomaterials should be biologically evaluated.