UV Sterilization Effects and Osteoblast Proliferation on Amorphous Carbon Films Classified Based on Optical Constants.

Optical classification methods that distinguish amorphous carbon films into six types based on refractive index and extinction coefficient have garnered increasing attention. In this study, five types of amorphous carbon films were prepared on Si substrates using different plasma processes, including physical and chemical vapor deposition. The refractive index and extinction coefficient of the amorphous carbon films were measured using spectroscopic ellipsometry, and the samples were classified into five amorphous carbon types-amorphous, hydrogenated amorphous, tetrahedral amorphous, polymer-like, and graphite-like carbon-based on optical constants. Each amorphous carbon type was irradiated with 253.7 nm UV treatment; the structure and surface properties of each were investigated before and after UV treatment. No significant changes were observed in film structure nor surface oxidation after UV sterilization progressed at approximately the same level for all amorphous carbon types. Osteoblast proliferation associated with amorphous carbon types was evaluated in vitro. Graphite-like carbon, which has relatively high surface oxidation levels, was associated with higher osteoblast proliferation levels than the other carbon types. Our findings inform the selection of suitable amorphous carbon types based on optical constants for use in specific medical devices related to osteoblasts, such as artificial joints and dental implants.

Correlation of Cell Proliferation with Surface Properties of Polymer-like Carbon Films of Different Thicknesses Prepared by a Radio-Frequency Plasma CVD Process.

In this study, correlation of cell proliferation with surface properties of the polymer-like carbon (PLC) films of different thicknesses prepared by radio-frequency plasma CVD are investigated. Four PLC samples were prepared via radio frequency plasma chemical vapor deposition on Si substrates. Each PLC film was analyzed using spectroscopic ellipsometry to determine its thickness, refractive index (n), and extinction coefficient (k); the thickness ranged from 29.0 to 356.5 nm. Based on their n−k plots, all the samples were classified as PLC-type films. The biological response of the PLC films was evaluated in vitro using a cell culture. The samples with relatively thick PLC films (>300 nm) exhibited stronger cell proliferation properties than those with thinner films. Moreover, the results of the surface analysis showed no significant differences in the surface composition of those PLC samples, as analyzed using X-ray photoelectron spectroscopy, but that as the PLC films became thicker, their surfaces became rougher on the nanoscale and their wettability improved. Overall, this study showed that careful control of the film growth of PLC films, which affects their surface properties, is essential for their use in bio-interface applications.

Osteoblastic MC3T3-E1 cells on diamond-like carbon-coated silicon plates: Field emission scanning electron microscopy data.

Diamond-like carbon (DLC) is an amorphous form of carbon that contains aspects of both the diamond and graphite structures. It is composed of carbon and hydrogen, and owing to its texture, high mechanical hardness, chemical inertness, and optical transparency, DLC is widely used as a protective coating in the form of a thin film, which is applied to the surfaces of many materials. Recently, it has attracted attention as a biomedical material because of its high biocompatibility and stability [1,2]. DLC is particularly suitable to be embedded in the body owing to its low friction properties and selective cell surface attachment properties [3]. The material is currently being developed for the treatment of bone fractures [4]. However, unlike fibroblasts, the attachment of osteoblasts has not been extensively examined and no morphological data is available on how osteoblastic cells form contacts with the surface of biocompatible DLC-coated materials. Herein, such data were collected by coating DLC on the surface of silicon plates. The attachment of mouse cells to the DLC-coated plates was examined by colorimetric cell proliferation assay, and morphological observations were made using a field emission scanning electron microscope. Also, the flat cross section of the cell and plate was obtained by the ion milling method.

Blood viscometer applying electromagnetically spinning method.

Viscosity is an important parameter which affects hemodynamics during extracorporeal circulation and long-term cardiac support. In this study, we have aimed to develop a novel viscometer with which we can easily measure blood viscosity by applying the electromagnetically spinning (EMS) method. In the EMS method, we can rotate an aluminum ball 2 mm in diameter indirectly in a test tube with 0.3 ml sample of a liquid by utilizing the moment caused by the Lorentz force as well as separate the test tube from the viscometer body. First, we calibrated the EMS viscometer by means of liquid samples with known viscosities and computational fluid dynamics. Then, when we measured the viscosity of 9.4 mPa s silicone oil in order to evaluate the performance of the EMS viscometer, the mean viscosity was found to be 9.55 ± 0.10 mPa s at available shear rates from 10 to 240 s(-1). Finally, we measured the viscosity of bovine blood. We prepared four blood samples whose hematocrit levels were adjusted to 23, 45, 50, and 70% and a plasma sample without hemocyte components. As a result, the measurements of blood viscosities showed obedience to Casson's equation. We found that the viscosity was approximately constant in Newtonian silicone oil, whereas the viscosity decreased with increasing shear rate in non-Newtonian bovine blood. These results suggest that the EMS viscometer will be useful to measure blood viscosity at the clinical site.

Dissolution effect and cytotoxicity of diamond-like carbon coatings on orthodontic archwires.

Nickel-titanium (NiTi) has been used for implants in orthodontics due to the unique properties such as shape memory effect and superelasticity. However, NiTi alloys are eroded in the oral cavity because they are immersed by saliva with enzymolysis. Their reactions lead corrosion and nickel release into the body. The higher concentrations of Ni release may generate harmful reactions. Ni release causes allergenic, toxic and carcinogenic reactions. It is well known that diamond-like carbon (DLC) films have excellent properties, such as extreme hardness, low friction coefficients, high wear resistance. In addition, DLC film has many other superior properties as a protective coating for biomedical applications such as biocompatibility and chemical inertness. Therefore, DLC film has received enormous attention as a biocompatible coating. In this study, DLC film coated NiTi orthodontic archwires to protect Ni release into the oral cavity. Each wire was immersed in physiological saline at the temperature 37 degrees C for 6 months. The release concentration of Ni ions was detected using microwave induced plasma mass spectrometry (MIP-MS) with the resolution of ppb level. The toxic effect of Ni release was studied the cell growth using squamous carcinoma cells. These cells were seeded in 24 well culture plates and materials were immersed in each well directly. The concentration of Ni ions in the solutions had been reduced one-sixth by DLC films when compared with non-coated wire. This study indicated that DLC films have the protective effect of the diffusion and the non-cytotoxicity in corrosive environment.

Investigating the functionality of diamond-like carbon films on an artificial heart diaphragm.

In this study, the authors used diamond-like carbon film to coat the ellipsoidal diaphragm (polyurethane elastomer) of artificial hearts. The purpose of such coatings is to prevent the penetration of hydraulic silicone oil and blood through the diaphragm. To attach diamond-like carbon film uniformly on the diaphragm, the authors developed a special electrode. In estimating the uniformity of the diamond-like carbon film, the thickness was measured using a scanning electron microscope, and the characteristics of the diamond-like carbon film was investigated using infrared spectroscopy, Ar-laser Raman spectrophotometer, and x-ray photoelectron spectrometer. Also, to estimate the penetration of silicone oil through the diaphragm, in vitro testing was operated by alternating the pressure of silicone oil for 20 days. The authors were able to successfully attach uniform deposition of diamond-like carbon film on the ellipsoidal diaphragm. In this in vitro test, diamond-like carbon film was proven to have good stability. The amount of silicone oil penetration was improved by one-third using the diamond-like carbon film coating compared with an uncoated diaphragm. It is expected that through the use of the diamond-like carbon film, the dynamic compatibility of an artificial heart diaphragm will increase.