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Gold nanoparticles have been commonly made by a wet process from chloroauric acid or dry process using vacuum evaporation to solid surfaces. Here, we have shown a method to make gold particle from ...

We evaluated the surface characteristics of polystyrene (PS) exposed to active oxygen species (AOS) in comparison with the surface characteristics of commercially available PS irradiated with oxyge...

Spindt-type emitters were fabricated with cavities made of Al/Mo/SiO2 using the triode high power pulsed magnetron sputtering method. We explored the process parameters (gas pressure and voltage of the additional cap electrode) to optimize the sharpness of the emitter shape. We found that the intermediate pressure and voltage were suited to obtain sharp emitters. Further, we elucidated the crucial effect of the cavity dimensions, such as the cavity depth and hole diameter in the cavity ceiling, on the emitter shape. At a cavity depth of 480 nm, the aspect ratio (AR) of the emitter increased monotonously with an increase in the hole diameter. With a large hole diameter (900 nm) and even shallower cavity (380 nm depth), we attempted to reoptimize the process parameters. Consequently, a very sharp emitter cone structure with an AR exceeding 1.3 was obtained. The cap voltage that produced the optimum AR was found to decrease for the larger-hole and shallower-depth cavities. Finally, the applicability of the process for preparing a working emitter is discussed.

Surface modification of polystyrene (PS) dish used for cell culture substrate is necessary to enhance cell adhesion and spreading. Generally, plasma treatment is employed for enhancement of hydrophilic surface at the PS dish surface, and sterilization treatment of the PS dish is performed after the plasma treatment. Simultaneous process of the surface modification and sterilization is required, and we have investigated surface modification effects on the PS dish in a sterilization bag by using active oxygen species (AOS) generated via ultraviolet (UV) lamps. It is considered that excited oxygen molecules ( 1 O 2 ) as well as ozone (O 3 ) generated via the UV lamps greatly affect surface modification of the PS dish in the sterilization bag. Cell adhesion and spreading characteristics of the modified PS dish by the AOS were almost the same level as those onto the commercially available PS dish. In addition, homogeneity of the surface modification is slightly enhanced compared to that of the commercially available PS dish. As microbes are sterilized by the AOS exposure in sterilization bag, surface modification of the PS dish is simultaneously achieved with the sterilization.

The growth of the target erosion profile (racetrack) in DC magnetron sputtering has been experimentally studied at a modest target power. Unbalanced magnetron sputtering (UBMS) and balanced magnetron sputtering (BMS) of a copper target were conducted at Ar gas pressures between 0.38–2.0Pa at a constant DC discharge power of 100W. At time intervals of several hours throughout the target life, the target was removed from the chamber, and its erosion profile was measured with a height gauge. The racetrack width was found to have an interesting pressure dependence. Higher argon gas pressure resulted in a wider initial track width in both the UBMS and BMS configurations. As the sputter erosion of the target proceeded, the track width became narrower at higher gas pressures (≥1.0Pa). At lower gas pressures, the track width was mostly unchanged and even showed a slight increase in the case of 0.38Pa in UBMS. As a result, the order of the final width was reversed: the higher gas pressure resulted in a narrower track width. The origin of this behavior was ascribed to the difference in the plasma sheath thickness and the free path of secondary electrons.

2,2,6,6-Tetramethyl-4-piperidinol (TEMP) is a spin-trap agent for electron spin resonance (ESR) that is usually employed in solution. However, in this study, TEMP is mixed with hydroxypropyl methyl...

Human embryonic kidney 293T (HEK293T) cells are used in various biological experiments and researches. In this study, we investigated the effect of cell culture environments on morphological and functional properties of HEK293T cells. We used several kinds of dishes made of polystyrene or glass for cell culture, including three types of polystyrene dishes provided from different manufacturers for suspension and adherent cell culture. In addition, we also investigated the effect of culturing on gelatin-coated surfaces on the cell morphology. We found that HEK293T cells aggregated and formed into three-dimensional (3-D) multicellular spheroids (MCS) when non-coated polystyrene dishes were used for suspension culture. In particular, the non-coated polystyrene dish from Sumitomo bakelite is the most remarkable characteristic for 3-D MCS among the polystyrene dishes. On the other hand, HEK293T cells hardly aggregated and formed 3-D MCS on gelatin-coated polystyrene dishes for suspension culture. HEK293T cells adhered on the non- or gelatin-coated polystyrene dish for adherent culture, but they did not form 3-D MCS. HEK293T cells also adhered to non- or gelatin-coated glass dishes and did not form 3-D MCS in serum-free medium. These results suggest that HEK293T cells cultured on non-coated polystyrene dish may be useful for the tool to analyze the characteristics of 3D-MCS. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s10616-019-00363-w) contains supplementary material, which is available to authorized users.

The present study was conducted to determine the effects of a nano-periodic-structured surface on the morphological and mechanical properties of a stem-cell-based self-assembled tissue (scSAT) developed for biological tissue repair. Nano-periodic groove structures were patterned on a pure titanium surface using femtosecond laser processing, and the structure was replicated on polydimethylsiloxane (PDMS). The depth, periodic pitch, and surface roughness (Ra) of the PDMS grooves were 48 ± 21 nm, 522 ± 9 nm, and 17 ± 5 nm, respectively. Human synovial cells, including mesenchymal stem cells, were subjected to 4-time cell passage, and then cultured on the PDMS surface at a density of 4.0 × 105cells/cm2in a growth medium with 0.2 mM ascorbic acid 2-phosphate to produce scSATs (nano-scSAT). For comparison, some of the cells subjected to 4-time cell passage were cultured on either a flat PDMS substrate with 6 ± 1 nm of surface roughness (Ra) (flat-scSAT) or a commercially available cell culture plate of polystyrene (normal-scSAT), at a cell density identical to that in the nano-scSAT group. At 28 days of cell culture, the scSATs were gently detached from the culture plates and subjected to morphological observation and mechanical testing. Microscopic observation revealed that the nano-scSATs exhibited a dense tissue of cells and an extracellular matrix with an anisotropic structure, while the flat- and normal-scSATs exhibited a sparse and isotropic structure. The tangent modulus and tensile strength were significantly higher in the nano-scSATs than in the flat- and normal-scSATs. These results suggest that a nano-periodic-structured surface improves the morphological and mechanical properties of scSATs.

Methylene blue based on the nafion film was prepared and chemical reactions in contact with active oxygen species were estimated. In addition, decolorization mechanism of the film due to exposure of the active oxygen species is discussed. The active oxygen species was exposed to the methylene blue based on the nafion film in low and high humidity conditions. Although decolorization of the film was hardly observed when it was exposed in the ozone and the active oxygen species in low humidity condition, the decolorization was observed when it was exposed in the high humidity condition. It is considered that the decolorization of the film due the active oxygen species exposure relates to the degradation reaction of the methylene blue molecule due to hydroxyl radicals.

For efficient industrial application, it is necessary to understand the formation mechanisms of active oxygen species under ultraviolet (UV) light irradiation. In this study, active oxygen was generated by UV lamps (providing wavelengths of 185 and 254 nm) at two different humidity levels. The generation of excited singlet oxygen [O(1D)] and hydroxyl radicals (OH*) in the atmosphere were detected using the electron spin resonance (ESR) method, while ozone (O3) was detected using a gas tube. The concentrations of O(1D) and O3 generated under low humidity conditions were much higher than those generated at high humidity. On the other hand, the concentration of OH* generated under high humidity condition were much higher than that generated at low humidity. The amount of O(1D) increased linearly with irradiation time, while the increase of O3 concentration was observed to be suppressed after 5 min. Fluorocarbon thin films r.f.-sputtered onto quartz crystal oscillators were used to investigate the etching behavior of generated active oxygen species. The etching rates were found to be higher at high humidity, which is believed to be due to the contribution of OH* whose concentration was higher in the presence of larger amounts of water in the atmosphere.

Sputtering is one of effective technologies to enhance functions of polymer film surfaces, and polymer film coating by the sputtering is one of the surface modification technologies. Polyimide (PI) has good thermal and chemical stabilities, and excellent mechanical property, and high performance PI films can be achieved by controlling of nanostructured surfaces, e.g., hydrophobic PI film can be applied for precision instruments such as printer transfer belt. Polytetrafluoroethylene (PTFE) has also excellent thermal and chemical stabilities, lubricant and insulating properties and hydrophobicity, however, it is difficult to form the PTFE thin film on a polymer film substrate without peeling. Although PTFE thin film was deposited onto a PI film substrate by r.f. sputtering to enhance the hydrophobicity of the PI film substrate, there still remains a serious drawback in the adhesion between the sputtered PTFE thin film and the PI film substrate. A copper (Cu) thin film was introduced between the PTFE thin film and PI film substrate (PTFE/Cu/PI). Although the surface roughness and hydrophobicity of the PTFE/PI laminate decreased due to the introduction of the Cu thin film layer, the adhesion between the sputtered PTFE thin film and PI film substrate was improved without deterioration of wear durability.

Four carbonated apatite films having average thicknesses of 1.3–0.11 μm, proportions of network sizes above 10 μm of 41–68%, and average border heights of the characteristic network structure of 0.98–0.29 μm were fabricated on a titanium plate by aqueous spray coating. These carbonated apatite films after heat treatment showed good mineralization ability in Hanks' balanced salt solution. Assessment of initial cell attachment and calcination on these films and on the Ti plate using osteoblastic MC3T3-E1 indicated that the carbonated apatite film heat treated at 600 °C, whose film thickness, proportion of network sizes above 10 μm, and border height were 0.11 μm, 61%, and 0.31 μm, respectively, was most preferred by osteoblastic cells. Field emission scanning electron microscopic observation of the cells attached to the films showed that the wide network and low border height of the network structure on the carbonated apatite film play an important role in the development of the filopodia of the osteoblastic cells.

The effect of a cell-adhesive peptide containing Arg-Gly-Asp (RGD) immobilized through poly(ethylene glycol) (PEG) on titanium (Ti) on calcification by MC3T3-E1 cells was investigated to develop a new surface modification technique using biofunctional molecules. RGD was immobilized on Ti through PEG, both terminals of which were terminated with –NH2 and –COOH to combine with the Ti surface and RGD. PEG was immobilized on Ti with electrodeposition, and RGD, with immersion. For comparison, glycine was employed because it is the simplest molecule containing both –NH2 and –COOH at its terminals. MC3T3-E1 cells were cultured and differentiation-induced on each specimen, and the cell calcification properties were investigated. As a result, there was no significant difference in the morphology and extension of MC3T3-E1 cells cultured on each specimen, while the number of cells cultured on RGD/PEG/Ti was the largest. After differentiation-induction, there was no significant difference in the ALP activity among all specimens. On the other hand, the level of cell calcification on RGD/PEG/Ti was the highest. Therefore, the hard tissue compatibility of Ti is improved by immobilizing RGD through functional molecules which have a long molecular chain.

We have been investigating an advanced sterilization system that employs active oxygen species (AOS). We designed the sterilization equipment, including an evacuation system, which generates AOS from pure oxygen gas using ultraviolet irradiation, in order to study the conditions necessary for sterilization in the system's chamber. Using Geobachillus stearothermophilus spores (10(6) CFU) in a sterile bag as a biological indicator (BI) in the chamber of the AOS sterilization apparatus, we examined the viability of the BI as a function of exposure time, assessing the role of the decompression level in the sterilization performance. We found that the survival curves showed exponential reduction, and that the decompression level did not exert a significant influence on the survival curve. Subsequently, we investigated the sterilization effect as influenced by the spatial and environmental temperature variation throughout the chamber, and found that the sterilization effect varied with position, due to the varying environmental temperature in the respective areas. We confirmed that temperature is one of the most important factors influencing sterilization in the chamber, and estimated the temperature effect on the distribution of atomic oxygen concentration, using the quartz crystal microbalance (QCM) method with fluorocarbon thin film prepared by radio frequency sputtering.

In this study, an array of Mo cones for volcano-structured Spindt-type microelectron emitters were fabricated. A recently developed triode high power pulsed magnetron sputtering system was used to control the positive plasma potential and efficiently accelerate ion species. By applying a proper positive voltage to the additional electrode, the authors obtained good cone shapes with high aspect ratios in a water-cooled microcavity structure made of two resist layers, which was previously impossible by conventional vacuum evaporation techniques. The effects of ion acceleration on the alignment of ions along the normal direction, as well as on the stress in the deposited film, are discussed. The former is important for the formation of sharp cones, while the latter is crucial for achieving stable fabrication.

A novel coating technique of thin ceramic layer resembling teeth color on titanium (Ti) surface was developed by combination of sputter deposition of metal zirconium (Zr) and subsequent micro-arc oxidation (MAO) treatment. The oxide layer grown by MAO treatment had a porous structure with a thickness of approximately 6 micrometers and was mainly composed of zirconium dioxide (ZrO(2)) with both tetragonal and monoclinic crystal structures. The surface of the specimen was hardened by this technique, and the hardness of the specimen was significantly larger than that of untreated Ti and MAO-treated Ti without Zr layer. The bonding strength test revealed that fracture occurred inside the oxide layer, indicating that adhesion between the oxide layer and the Ti substrate was sufficiently strong. From these results, this technique has an advantage for the development of novel dental materials with excellent mechanical and aesthetic properties.

Introduction Stem cell-based tissue engineered construct (TEC) biosynthesized from synovium-derived mesenchymal stem cells (MSCs) has a great potential for repairing and regenerating ligaments and tendons1. However, the mechanical and structural properties of the TEC were insufficient for clinical applications. A candidate solution to the problem is to promote the generation of the extracellularmatrix inthe TECusing a special culture withcollagen sheets (CS). Previous studies indicated thattheCS has an abilitytorepair fibrous tissuesin vivo4. In addition, the biosynthesis of extracellular matrix is promoted by cell culturing in the existence of collagen. 2 In the present study, TECwas culturedwiththe CS, then the tensile properties of TEC/CS composite were assessed. Materials and Methods The CS wasproduced from porcine corium-derived collagen-rich tissues, through homogenization, centrifugal separation, filtering, and dehydration. It should be noted that the sheets are porous and chemical agent-free materials with collagen density between 20 and 30%. MSCswere obtained from the synovial membranes of human knee joint by means of collagenase treatment. After 5 time passages, the cells were plated at the density of 4.0 × 105 cells/cm2 on the CS (TEC/CS), and ontissue culturepolystyrenedishes (TEC). The cells were culturedto produce construct of extracellular matrix for 1, 4, and 8 weeks in the DMEM1. In addition, the CS was also immersed in the same medium without cells for 4 weeks (CS). TEC/CS, TEC, and CS weresubjected to tensiletest at arate of 0.05 mm/s in a PBS solution at 37 °C using acustom-made micro tensile tester. 3 Morphological observations of the tissues were carried out using a scanning electron microscopic (SEM)and an optical microscope with hematoxylin-eosin (HE) staining. Results and discussion The tangent modulus and tensile strengthofTEC/CSgroupwere continuously increased. In addition, those of TEC/CS after 8-week cultivation were significantly higher than those of CS. The load at failure of TEC/CS group was significantly lower than those of CS and TEC groups at 1 week. However, it was increased subsequently and reached to 0.18 ± 0.05 N at 8 weeks, with significant differences vs. CS (0.07 ± 0.02 N) and TEC (0.12 ± 0.05 N) groups. References 1 Ando W, et al . Biomaterials. 2007;28:5462–5470 2 Gentleman E, et al . Biomaterials. 2003;24: 3805–3813 3 Nagai H, et al . Japanese Jounal of Clinical Biomechanics . 2006;27:89–93 [in Japanese] 4 Suzuki D, et al . abstract. Jounal of Japanese Clinical Biomechanics. 39

The roughness and cleanness of a titanium surface must be controlled in order to investigate the expression mechanism of hard tissue compatibility on titanium. In this study, osteogenic MC3T3-E1 cells were cultured and differentiation-induced on bulk and sputter-deposited titanium specimens, and the osteogenesis were investigated. For the preparation of bulk specimens, titanium discs were mirror-polished. On the other hand, titanium was sputter-deposited on smooth and clean cover glasses as sputter-deposited specimens. As a result, no significant difference was observed in the cell morphology and attached number. On the other hand, the time showing maximum activity in the alkaline phosphatase and gene expressions, which are related to bone differentiation on the bulk titanium, were superior to those on the sputter-deposited titanium. From the surface observation of the specimens with a scanning electron microscope and a scanning probe microscope, the surface on the sputter-deposited titanium was more uniform and cleaner than that on the bulk titanium. According to X-ray photoelectron spectroscopy, the thickness of surface oxide film on the sputter-deposited titanium was smaller than that on the bulk titanium. In addition, the proportions of TiO and Ti2O3 in the surface oxide film on the sputter-deposited titanium were larger than those on the bulk titanium. These differences might influence the differentiation of osteoblastic cells. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010

The microstructures and magnetic susceptibilities of Zr-Mo alloys were investigated to develop a Zr alloy with a low magnetic susceptibility for magnetic resonance imaging (MRI). The microstructure was evaluated with an X-ray diffractometer (XRD), an optical microscope (OM) and a transmission electron microscope (TEM), and the magnetic susceptibility was measured with a magnetic susceptibility balance. The alpha' phase with acicular structure was dominant in Zr-1Mo alloys, while the omega and beta phases with the equiaxed and relatively flat (no acicular) microstructure was dominant in Zr-3Mo. The mixed microstructural features of Zr-1Mo and Zr-3Mo were observed in Zr-2Mo, which consists of the alpha', omega and beta phases. The beta phase is stabilized when the Mo content exceeds over 3 mass% Mo. As-cast Zr-Mo alloys showed a minimum value of magnetic susceptibility at 3 mass% Mo, and the value abruptly increased up to 10% Mo before remaining stable up to 15 mass% Mo. XRD, OM and TEM revealed that the minimum value of the susceptibility was closely related to the appearance of the athermal omega phase in the beta phase. As the Mo content decreases from 3 mass%, the alpha' phase appears with the omega and beta phases. On the other hand, as the Mo content increases from 3 mass%, the beta phase increases and the omega phase decreases. Thus the appearance of the alpha' and beta phase leads to an increase in magnetic susceptibility. The magnetic susceptibility of as-cast Zr-3Mo alloy was almost one-third that of Ti-6Al-4V, which is commonly used for medical implant devices. Zr-Mo alloys are useful for medical devices used under MRI.