This study examined whether Portland cement powder in acrylic resin could form crystals on specimen surfaces in long-term water storage, as determined using scanning electron microscopy (SEM), X-ray diffractometry (XRD), and X-ray photoelectron spectrometry (XPS). Portland cement/resin composites were prepared with 50 mass% Portland cement and 50 mass% acrylic resin. The Portland cement/resin composites were stored in water for 0 (control), 50 and 100 days. After each period, the disk surfaces were examined by SEM, XRD and XPS. The SEM analysis showed mineralization products on the composite disk surfaces after 50 and 100 days of storage. By XPS analysis, calcium- and silicon-rich layers were found on the composite surfaces. XRD analysis of mineralized deposits on resin disks identified calcium carbonate. The results of these water-soaking experiments demonstrate that surface precipitation of mineralization deposits is a common behavior of the experimental Portland cement/resin composite over 50 days in water.
To make orthodontic adhesives visible as needed is valuable for safer and complete removal of them after orthodontic treatments. An attempt was made on doping trivalent europium ions into lattices of zinc oxides to make orthodontic adhesives visible by irradiation with purple or near ultraviolet light. The primary crystals of the synthesized products exhibited various sizes. However, overall, their diameters were on the nanoscale. The XRD patterns of them were in good agreement with those of hexagonal ZnO. However, the patterns also indicated the existence of another crystalline substance that could be indexed as Eu2O3. These results lead to the conclusion that ZnO:Eu3+ nanoparticles were suitably synthesized via a homogeneous precipitation method. As for the polymer adhesives containing the ZnO:Eu3+ nanoparticles, the photoluminescent spectra exhibited characteristic excitation and emission peaks corresponding to the intrinsic intra-4f transitions of Eu3+. In addition, the yielding loads of the composite specimens did not deteriorate, regardless of the concentration of the ZnO:Eu3+ nanoparticles within the proportion of 1–3 wt%. The results obtained in this study suggest that the introduction of Eu3+-doped ZnO nanoparticles into orthodontic adhesives is feasible.
In this study, we investigated a conductivity preparation for scanning electron microscope (SEM) observation that uses a solution containing the room temperature ionic liquid (RTIL) choline lactate, which is a natural product–based tertaammonium salt. By only immersion in the choline solution, clear SEM images of biological matter were successfully observed. In addition, we also succeeded in applying the RTIL preparation to energy-dispersed fluorescent X-ray spectroscopy (EDS) and elemental distribution mapping (SEM-EDS). This is the first time that RTIL preparation has been applied to SEM-EDS measurement instead of conventional pretreatment such as carbon sputtering. These results suggested that simple and rapid conductivity preparation using the RTIL solution can be widely applied not only SEM observation but also to SEM-EDS of a variety of living mater.
We have investigated the effects of diamond particles made of the same carbons as fullerene and nanocarbon using an in vitro angiogenesis kit (Toyobo). An undiluted solution had a few effects on the tubule-like structure formation area. However, the effects became smaller at higher dilution rates; no significant difference was observed between the eightfold dilution and control. In vitro angiogenesis has significant effects on tissue regeneration with diamond particles. Dental diamond points are frequently used for cutting and grinding. Thus, a detailed analysis is required of the relationship between diamond particles and angiogenesis.
In this study, we synthesized two types of biomimetic enzyme analogues, a macromolecules-type, and a surface modified particle type. Both of the biomimetic enzymes promoted selective hydroxyapatite formation and carbonate ion induction. Therefore, the biomimetic enzymes can be used to 1) accelerate the calcification reaction, 2) control the crystal phase, and 3) incorporate carbonate ion in hydroxylapatite. These properties can allow us to develop several carbonated hydroxyapatite materials that have potential in applications such as bone tissue engineering.
It is widely known that carbon nanotubes (CNTs) have various characteristics, and many studies had reported about biomaterial application of CNTs for that biocompatibility. The increase of alkaline phosphatase activity and well adhesion extension were confirmed when cell culture experiments were carried out on CNTs. It indicated that one of the most important factors to affect on biocompatibility of CNTs is the adsorption of proteins. To investigate the adsorption behavior of proteins to CNTs, liquid chromatography method was applied in this study. CNTs that purity was less than 70% and had a curled shape were used. Thermal and acid treatments were required to remove impurities such as amorphous carbon and metallic catalysts. It was also aimed whether the pretreatment conditions affected the adsorption behavior of proteins. CNTs with only acid treatment showed much stronger adsorption to proteins. CNTs with only thermal treatment and CNTs with thermal and acid treatment also showed the same adsorption behavior. On the other hand, CNTs with prolonged thermal treatment and acid treatment showed weaker adsorption to proteins. CNTs that purity was more than 95% and had a straight shape were also experimented in contrast. The adsorption of proteins was not confirmed. The results suggested that affinity to proteins affected by the difference of morphology and conditions of purification treatment of CNTs.
Guided Bone Regeneration (GBR) has been developed for bone recovery at locally compromised sites, facilitating cell proliferation, angiogenesis and osteogenesis, and eliminating fibroblastic interference with membranes. Many studies have been conducted to develop an ideal GBR membrane, and are in pursuit of equipping such a material with certain properties, such as high biocompatibility, appropriate resorbability, technical convenience and mechanical strength. This search has currently led to the use of expanded polytetrafluoroethylene, synthetic polyesters and collagen. Furthermore, the integration of a biological role, such as the sustained release of chemical agents, is assumed to provide the membrane with a higher bone repair efficacy. Gelatin and hydrophobized polysaccharide membranes, and their anticipated characteristics, would not only maintain a space for newly formed bone but also act as a reservoir for biologically active molecules to accelerate bone healing.