Photocatalytic TiO₂ was coated on a stainless steel (SUS316L) substrate via a sol-gel method at a calcination temperature of 600°C. The sol-gel precursor (titanium isopropoxide) solution was modified by adding crystalline (anatase or rutile) TiO₂ particles to control the crystal phase of the TiO₂ coated on the substrate. The effect of the number of TiO₂ coatings was also evaluated. The TiO₂ coating was characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The photocatalytic activity was evaluated from the degradation of methylene blue solution on the TiO₂ coating after UV irradiation. The amount of bacteria adhered on the substrate was also evaluated. The TiO₂ coating comprising a binary phase (anatase/rutile weight ratio = 4.9/5.1) showed the highest photocatalytic activity, which improved after increasing the number of coatings. The amount of bacteria adhered on each TiO₂-coated substrate was not significantly different from that on the uncoated substrate.

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Alpha-tricalcium phosphate (α-TCP) has been investigated extensively as an artificial bone graft; however, the relationship between size of α-TCP particles and its bone-formation capability is not clear. In the present study, we compared the bone-formation capability of two different sized porous α-TCP particles (α-TCP200 [under 200 μm], and α-TCP600 [500–600 μm]) in critical-sized bone defects in mouse calvaria up to 12 wk after implantation. Scanning electron microscopy revealed that both particles possessed similar smooth surface with porous structure. Before implantation, inter-particle size and specific surface area of α-TCP200 were 27 μm and 0.40 m²/g and of α-TCP600 were 209 μm and 0.24 m²/g, respectively. Histomorphometric analysis after implantation of the particles revealed that both particles promoted osteoconduction. At 12 wk, α-TCP200 induced superior bone formation than α-TCP600. At 4 wk, α-TCP200 showed more hydrolysis than α-TCP600. These results indicate that the size of α-TCP particles may influence their bone-formation capability in critical-sized bone defects of mouse calvaria. This effect might be partially due to the difference in the hydrolysis speed of different-sized particles.

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In this study, we investigated the use of a room temperature ionic liquid (RTIL) for the pretreatment of wet biological samples for scanning electron microscopy (SEM). The characteristic properties of RTILs, such as high electroconductivity and no vapor pressure, makes them appropriate for the conductive preparation of samples for SEM. We found that only a drop of RTILs was required to immerse the sample surface and provide sufficient electroconductivity for high-quality SEM images. Furthermore, the RTILs pretreatment prevented the destruction and collapse of the wet, swollen biological samples, even under high vacuum conditions. Thus, this rapid and simple pretreatment allowed, SEM images of wet biological samples to be obtained as "living matter." These results suggest that the use of RTILs in the preparation of samples, particularly wet biological samples, can be a powerful tool for SEM.

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Stereolithography, a new molding technique for polymeric materials, should also be applied as a novel method to mold biomaterials into complex curved surfaces in a short period of time using three-dimensional CAD data, which cannot be achieved with conventional cutting methods. However, photocurable resins with potent toxicity have not traditionally been applied directly in vivo as medical materials. For their application to dental molding, photocurable resins with fewer biological risks should be developed.In the present study, we compared the differentiation rates of ES-D3 cells and the survival rates of Bulb/c 3T3 cells using liquid resins, the unpolymerized products of two epoxy resins and one acrylic photocurable resin, demonstrating less biological damage with the acrylic resins. With these, safer and more reliable photocurable resins will be available for use in both medical and dental fields. In addition, scaffolds for regenerative medicine should be developed using stereolithography.

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In this study, we demonstrated a simple preparation of size-controlled fullerene C₆₀ micro-/nano- particles. The fullerene particles were prepared through the reaction of fullerene C₆₀ with a diaminoalkane. The resultant particles were spherical and their size depended on the alkyl chain length of the diaminoalkane compounds. In addition, we successfully modified the hydrophilic surface of the fullerene nanoparticles using succinic anhydrite. The obtained hydrophilic particles are dispersible in water, and the resultant solution is injectable into animals. This surface modification, which involves the introduction of -COOH groups onto the particle surface, may allow the nanoparticle to be tethered to functional moieties such as fluorescence dyes, oligosaccharides, antibodies and drugs. Thus, these simple preparations can widely extend the application of these particles in various fields particularly in biology.

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