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This study aimed to analyze the incidence of subclinical rejection (SCR) in kidney transplantation patients and risk factors associated with SCR.We assessed 80 protocol biopsies taken within 2 years postoperatively in 41 adult patients who underwent living donor kidney transplantation between 2017 and 2020. All patients were on immunosuppressant therapy that included tacrolimus, mycophenolate mofetil, and steroids.The prevalence of Banff Borderline classification at 3, 6, and 12 months after transplantation was 4%, 5%, and 8 %, respectively, whereas none of the biopsies met the Banff criteria for acute T cell-mediated rejection throughout the study period. Active antibody-mediated rejection (ABMR) was only present in 8% of patients at 3 months after transplantation and chronic active ABMR at 6, 12, and 24 months after transplantation was detected in 10%, 13%, and 11% of the patients, respectively. Subgroup analysis revealed that 50% of the 6 patients with preformed anti-donor specific antibodies (DSAs) developed clinical or subclinical active ABMR within 3 months after transplantation, followed by chronic active ABMR according to serial histologic assessment. Conversely, only a small proportion of patients (3%) without preformed DSAs exhibited clinically active ABMR.SCR occurs too infrequently in patients with low immunologic risk and strong contemporary immunosuppression therapy to justify the diagnostic effort of serial protocol biopsies. However, protocol biopsies remain an indispensable tool in renal transplant monitoring and may be especially important in immunologically high-risk patients with pre-existing DSAs.

Silica nanotubes with controllable size were synthesized as the electrospun silk fibroin/gelatin composite nanofibers as novel sacrificial template were firstly coated with silica in the Stober-type sol-gel precursor and then burned out at 600 °C. The aqueous stability of composite nanofibers was much better than that of gelatin nanofibers due to the presence of silk fibroin. FT-IR spectrum showed that silica nanotubes had the strong adsorption band at 1115 cm−1 for Si–O–Si groups. TEM observation showed that the diameter of silica nanotubes could be controlled from 225 ± 11 nm to 470 ± 9 nm by tuning the silk fibroin/gelatin weight ratio from 1.25 to 2. After incubation with the osteoblast MG63 cells, silica nanotubes (0–200 μg/mL) had no significant cytotoxicity and presented excellent biocompatibility.

Petal-like titania layer was obtained on the 3D-printing 316L stainless steel substrate by two-step method at low temperature. Liquid phase deposition (LPD) method was used to prepare the fluorine-containing titania transition layer as step 1, not only improving the binding force with the substrate, but also contributing to the deposition of the second bioactive layer obtained by hydrothermal method in step 2. The samples were analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive spectrometry (EDS), X-ray fluorescence (XRF) and static state contact angle. The XRF result indicated that the fluorine could be effectively concealed by Petal-like layer in step 2. And the wettability test showed that the as-treated samples were hydrophilic. Furthermore, the calcium-deficient amorphous calcium phosphate (ACP) layer was induced on the as-treated samples via being soaked in 1.5 times simulated body fluid (1.5SBF) solution within 3 days. Meanwhile, the biocompatibility results showed that the adhesion morphology and the quantity of osteoblasts on the sample treated by two-step method were better than the other sample groups. In a word, this two-step method is expected as a novel approach to improve the biocompatibility of the 3D-printing customized biomedical stainless steel.

High crystallinity anatase/rutile layers are prepared on the surface of commercially pure titanium (cpTi) by hydrothermal method at 160 °C for 3 h. The surface morphology of titania layers is changed by adjusting the pH value and Ti4+concentration of treating solution (TS). Obtained nanorods on all TS samples are composed of pure rutile and the anatase co-deposited with rutile is found in the dense bottom layer. The possible co-deposition mechanism of polymorphs layers is given in this study. In this study, the rutile nanorods array with high energy (101) facet exposed is found on the TS3 sample. In vitro apatite forming ability of the TS samples are confirmed by soaking them in Kokubo's simulated body fluid (SBF, pH 7.4, 36.5 °C) for 1 and 3 days. Results show that apatite particles could be obtained on all TS samples within 1 d. After 3 days' immersion in SBF, TS3 sample shows strongest apatite X-ray diffraction. These results indicate that the ability in inducing apatite on cpTi with TS3 treatment is excellent. Such excellent apatite-forming ability is ascribed to the existence of thick titania layer with high energy (101) facet exposed on the TS3 sample.

Ag-Co alloy films were fabricated at room temperature by magnetron sputtering. The results revealed that a large amount of polyhedral single-crystal Ag nanoparticles grow on the surface of Ag-Co alloy films, which is significantly different from the microstructure of Ag-Co alloy films on rigid substrates. Furthermore, after annealing, Ag atoms get enough energy to move toward the film surface and thus the mass and average size of Ag particles both increase with the increase of annealing temperatures. In addition, the average size of Ag particles decreases with the increase of annealing time but the particles per square micron increases. Amorphous Co is observed in the Ag-Co films and Ag grains in Ag-Co films become smaller, which indicates the growth of Ag grains is inhibited by Co. A new type of Ag particles / Ag-Co films with a convex structure is obtained and applied as SERS substrates, where the characteristic Raman spectra of 5 × 10−12 M R6G could be detected.

Objective: Infertility is a serious disease requiring timely treatment If treatment is delayed, the condition of patients may deteriorate over time The coronavirus (COVID-19) pandemic has seriously affected couples in need of immediate infertility treatment Because of stay-at-home guidance, fewer people are visiting medical facilities, and thus it may become necessary to provide online medical services, including infertility treatment Male-factor infertility contributes to about 50% of the incidence of infertility in couples Semen analysis is key to diagnosing reproductive potential in men In current practice, men must visit a clinic or other medical facility for semen analysis However, there are cases in which visiting a medical facility is problematic, as in the current pandemic To address this issue, many devices for at-home testing of semen samples have been developed and commercialized We have developed a service enabling infertility patients to receive medical advice by allowing them to easily share at-home smartphone semen test data with embryologists To verify the effectiveness of this system, we evaluated the correlation between at-home smartphone semen test data analyzed by embryologists and semen test results measured by computer assisted semen analysis (CASA) Design: Laboratory investigation Materials and Methods: We developed an online system that allows sperm videos captured using a smartphone microscope to be uploaded and shared with embryologists After receiving training on the online system, the embryologists viewed the videos on a large computer screen and recorded motile and static sperm counts Because the appearance of sperm captured in videos can differ depending on the type of smartphone, the embryologists measured sperm concentration and motility by estimating the size of the sperm head and tail A total of 45 human semen samples were analyzed using both the developed system and CASA software Each test was evaluated for compliance with World Health Organization semen testing criteria Results: Sperm concentration measured using the online system showed a very strong correlation with CASA results (P < 0 01, r = 0 89) Sperm motility analyzed by embryologists using the online system were significantly correlated with CASA results (P < 0 01, r = 0 74) Conclusions: Online medical care will likely become increasingly important during the COVID-19 pandemic The system we developed is a useful service allowing infertility patients to share at-home semen test data with embryologists Analysis of the test data by embryologists resulted in few mistakes compared with automatic machine analysis The system enables patients to connect with doctors and receive medical treatment online Services like this one could be become more common in the future

The initiation and propagation of damage are sensitive to temperature and strain rate, especially for ultra-super-critical rotor steel with high strength at elevated temperature, which probably leads to premature failure in the hot forming process. To accurately describe the damage behavior, a novel damage model incorporating temperature and strain rate was proposed based on Bonora damage model. To establish this damage model, a GA (genetic algorithm)-based inverse method was designed for identifying four damage parameters in Bonora damage model by correlating experimental and simulation data in the tensile tests at elevated temperatures and different strain rates. And then these damage parameters as functions of temperature and strain rate were determined. The proposed damage model was integrated into a finite element software FORGE to simulate the damage evolution of a notched upsetting specimen and the hot tensile specimens. The damage from compressive to tensile states and the fracture behavior were properly predicted, respectively. Additionally, the digital image correlation (DIC) technique was employed to capture the crack initiation and propagation on a flate notched X12 ultra-super-critical rotor steel specimen, which were compared with simulation results to further verify the accuracy of the proposed damage model.

Novel silica hollow flowers (1–5 μm) were synthesized using globular apatite flowers as sacrificed template via a sol–gel route and then employed as biocompatible carrier of bone morphogenetic protein-2 (BMP-2) to stimulate osteoblast differentiation. Apatite was bio-mimetically synthesized from a well-known Kokubo’s simulated body fluid (SBF), then coated with silica in a Stober-type silica sol–gel system, and finally dissolved in an acetic solution to yield silica hollow flowers. Analyses of SEM and TEM images show that the resultant silica flowers had a porous and hollow structure due to removal of apatite template by acetic treatment and their shell was constructed by numerous silica nanosheets (∼10 nm in silica shell). A larger specific surface of 890 m 2 /g was obtained for silica hollow flowers compared to silica-coated apatite due to the presence of porous and hollow structure. Silica hollow flowers had no significant toxicity after incubation with osteoblast MC3T3-E1 cells, indicating a good biocompatibility. They favored adsorption and supported a sustained release behavior of BMP-2. The released BMP-2 was biological active and enhanced osteoblast differentiation with higher ALP activity and larger amount of osteocalcin. The present silica hollow flowers are thus applicable to delivery system in tissue generation.

Rough nanostructured anatase TiO 2 surfaces containing many pores were prepared by the hydrothermal-based method. Surface modification with self-assembled monolayers (SAMs) of octadecylphosphonic acid (ODP) resulted in the superhydrophobic surface with an extremely high static water contact angle (CA) of 173.6° ± 1.7°. This superhydrophobic surface could be converted into a superhydrophilic surface with a water CA of nearly 0° by irradiating it with ultraviolet (UV) light, which induced photocatalytic decomposition of the ODP SAM. A superhydrophobic–superhydrophilic pattern with an extremely high wettability contrast (a water CA difference of over 170°) could be fabricated on the ODP-modified TiO 2 surface by area-selective UV irradiation through a photomask. This is the report of the TiO 2 -based superhydrophobic–superhydrophilic pattern with a water CA difference of over 170°, and it may be possible to use such patterns for various applications.

Porous hollow silica spheres were synthesized using silk fibroin spheres as novel single sacrificial template via a sol-gel route and their in vitro biocompatibility and drug delivery property were evaluated. TEM observation showed that silica spheres had a hollow cavity and a porous shell, while BET measurement showed that they had the pore size of 22 nm and specific surface area of 45 m 2 /g. FT-IR spectrum showed that silica spheres contained Si O Si bonds. After exposure to Hela cells, MTT assay indicated that silica spheres were in vitro biocompatible. It was found that silica spheres not only supported adsorption of tetracycline hydrochloride (TH, one of the representative antibiotics) with adsorption efficiency of 17.4%, but also exhibited a sustained release behavior for TH. The TH-loaded silica spheres showed antibacterial property to inhibit the growth of two representative bacteria: Escherichia coli and Staphylococcus aureus , indicating that the released TH was biologically active.

Objectives The functional monomer 10-methacryloxydecyl dihydrogen phosphate (10-MDP), recently used in more self-etch adhesives, chemically bonds to hydroxyapatite (HAp) and thus tooth tissue. Although the interfacial interaction of the phosphoric-acid functional group of 10-MDP with HAp-based substrates has well been documented, the effect of the long carbon-chain spacer of 10-MDP on the bonding effectiveness is far from understood. Methods We investigated three phosphoric-acid monomers, 2-methacryloyloxyethyl dihydrogen phosphate (2-MEP), 6-methacryloyloxyhexyl dihydrogen phosphate (6-MHP) and 10-MDP, that only differed for the length of the carbon chain, on their chemical interaction potential with HAp and dentin, this correlatively using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Commercial 6-MHP and 10-MDP containing adhesives were investigated as well. Results XRD revealed that on HAp only 10-MDP produced monomer-calcium salts in the form of ‘nano-layering’, while on dentin all monomers produced ‘nano-layering’, but with a varying intensity in the order of 10-MDP > 6-MHP > 2-MEP. TEM confirmed that 10-MDP formed the thickest hybrid and adhesive layer. XRD and TEM revealed ‘nano-layering’ for all commercial adhesives on dentin, though less intensively for the 6-MHP containing adhesive than for the 10-MDP ones. Significance It is concluded that not only the phosphoric-acid group but also the spacer group, and its length, affect the chemical interaction potential with HAp and dentin. In addition, the relatively strong ‘etching’ effect of 10-MDP forms more stable monomer-Ca salts, or ‘nano-layering’, than the two shorter carbon-chain monomers tested, thereby explaining, at least in part, the better bond durability documented with 10-MDP containing adhesives.

Following the "adhesion-decalcification" concept, specific functional monomers possess the capacity to primary chemically interact with hydroxyapatite (HAp). Such ionic bonding with synthetic HAp has been demonstrated for 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP), manifest as self-assembled "nanolayering". In continuation of that basic research this study aimed to explore whether nanolayering also occurs on enamel and dentin when a 10-MDP primer is applied following a common clinical application protocol. Therefore, the interaction of an experimental 10-MDP primer and a control, commercially available, 10-MDP-based primer (Clearfil SE Bond primer (C-SE), Kuraray) with enamel and dentin was characterized by X-ray diffraction (XRD), complemented with transmission electron microscopy interfacial ultrastructural data upon their reaction with enamel and dentin. In addition, XRD was used to study the effect of the concentration of 10-MDP on nanolayering on dentin. Finally, the stability of the nanolayers was determined by measuring the bond strength to enamel and dentin when a photoinitiator was added to the experimental primer or when interfacial polymerization depended solely on the photoinitiator supplied with the subsequently applied adhesive resin. XRD confirmed nanolayering on enamel and dentin, which was significantly greater on dentin than on enamel, and also when the surface was actively rubbed with the primer. Nanolayering was also proportional to the concentration of 10-MDP in the primer. Finally, the experimental primer needed the photoinitiator to obtain a tensile bond strength to dentin comparable with that of the control C-SE primer (which also contains a photoinitiator), but not when bonded to enamel. It is concluded that self-assembled nanolayering occurs on enamel and dentin, even when following a clinically used application protocol. The lower bonding effectiveness of mild self-etch adhesives to enamel should be ascribed in part to a lower chemical reactivity (nanolayering) with enamel HAp.

Although decayed/fractured teeth can be reconstructed minimally invasively and nearly invisibly using adhesive technology, the clinical longevity of dental composite restorations is still too short. Water sorption is thought to be the principal cause of destabilization of the biomaterial–tooth bond. However, the actual mechanisms of interfacial degradation are far from understood. Here we report how nano-controlled molecular interaction at the biomaterial–hard tissue interface can improve bond durability. The use of functional monomers with a strong chemical affinity for the calcium in hydroxyapatite is essential for long-term durability. Correlative X-ray diffraction and solid-state nuclear magnetic resonance disclosed a time-dependent molecular interaction at the interface with stable ionic bond formation of the monomer to hydroxyapatite competing in time with the deposition of less stable calcium phosphate salts. The advanced tooth–biomaterial interaction model gives not only an insight into the mechanisms of bond degradation, but also provides a basis to develop functional monomers for more durable tooth reconstruction.

Multilayer anatase films were coated by sol–gel technology on various substrates such as stainless-steel, alumina, and glass, respectively. Their in vitro apatite-forming ability was examined by immersion in Kokubo's simulated body fluid (SBF; pH 7.4, 36.5 °C). Although on anatase layer on alkali-free glass apatite was deposited within 7 d, no apatite was found on anatase deposited onto stainless steel, alumina or glass substrates within 7 d to prove they were bioinert. X-ray photoelectron spectroscopy was able to detect chromium, aluminum, or sodium on the surface of the anatase films. This indicated that these ions possibly inhibited the in vitro apatite-forming ability.

We attempted to prepare chitosan-silicate hybrid for use in a medical application and evaluated the physico-chemical properties and osteocompatibility of the hybrids as a function of gamma-glycidoxypropyltrimethoxysilane (GPTMS) concentration. Chitosan-silicate hybrids were synthesized using GPTMS as the reagent for cross-linking of the chitosan chains. Fourier transform infrared spectroscopy, (29)Si CP-MAS NMR spectroscopy and the ninhydrin assay were used to analyze the structures of the hybrids, and stress-strain curves were recorded to estimate their Young's modulus. The swelling ability, contact angle and cytocompatibility of the hybrids were investigated as a function of the GPTMS concentration. A certain fraction of GPTMS in each hybrid was linked at the epoxy group to the amino group of chitosan, which was associated with the change in the methoxysilane group of GPTMS due to hybridization. The cross-linking density was around 80% regardless of the volume of GPTMS. As the content of GPTMS increased, the water uptake decreased and the hydrophilicity of the hybrids increased except when the content exceeded amolar ratio of 1.5, when it caused a decrease. The values of the mechanical parameters assessed indicated that significant stiffening of the hybrids was obtained by the addition of GPTMS. The adhesion and proliferation of the MG63 osteoblast cells cultured on the chitosan-GPTMS hybrid surface were improved compared to those on the chitosan membrane, regardless of the GPTMS concentration. Moreover, human bone marrow osteoblast cells proliferated on the chitosan-GPTMS hybrid surface and formed a fibrillar extracellular matrix with numerous calcium phosphate globular structures, both in the presence and in the absence of dexamethasone. Therefore, the chitosan-GPTMS hybrids are promising candidates for basic materials that can promote bone regeneration because of their controllable composition (chitosan/GPTMS ratio).

Apatite formation on the surface of titanium and its alloys is effective for inducing osteoconductivity when implanted in bony defects. The aim of this study was to investigate the effects of thermal oxidation on apatite formation in macro-grooves on Ti-15Zr-4Ta-4Nb. Thermal oxidation at 500 and 600 degrees C in air led to modification of the Ti-15Zr-4Ta-4Nb surface to rutile phase titanium oxide. Ti-15Zr-4Ta-4Nb thermally oxidized at 500 degrees C in air showed no changes in metallographic structure, but not at 600 degrees C. After soaking in a simulated body fluid for 7days, the formation of apatite could be observed on the internal surfaces of macro-grooves 500mum deep and wide on Ti-15Zr-4Ta-4Nb thermally oxidized at 500 and 600 degrees C in air. These results indicate the potential for osteoconductivity of Ti-15Zr-4Ta-4Nb without changing its metallographic structure, by fabricating only the macro-grooves, i.e., spatial design, and by performing thermal oxidation at 500 degrees C.

Titania (anatase) gel powders were prepared by peptizing commercially available titania sols and heating them at temperatures up to 700 degrees C, as candidates for bilirubin adsorbents for blood purification therapy. Those titania particles were in contact with a protein solution containing bilirubin and bovine serum albumin that mimics the blood of bilirubinemia patients. The amount of free or direct bilirubin in the solution insignificant. Indirect bilirubin or a bilirubin complex with albumin was adsorbed on the anatase powders, the primary particle size of which was as large as or larger than the size of an albumin molecule. The surface charge and surface charge density were only minor factors in controlling the indirect bilirubin adsorption. The present results indicated that the size of primary particles and hydrophobicity were significant for the sol-derived anatase in terms of bilirubin adsorption, and both were controllable by the heating temperature and the time period.

Chitosan–silicate hybrids with 3D porous structures were prepared with freeze-drying precursor solutions derived from chitosan and γ-glycidoxypropyltrimethoxysilane (GPTMS). They were formed easily in any shape, such as sheets, pellets, disks, granules, and even roll-cakes. The pore size was strongly dependent on the freezing temperature: lower freezing temperature resulted smaller pores, about 110 μm for the hybrids frozen at −20 °C, and about 50 μm for those at −85 °C. The pore size was little dependent on the GPTMS content. In contrast, the GPTMS content affected porosity a littlie: ∼80% for chitosan, and ∼90% for the GPTMS-containing hybrids. Thus, their porous microstructure was controllable due to the freezing temperature and composition. MG63 osteoblastic cells were cultured up to 7 days on the porous hybrids. The cells adhered on the pore walls, proliferated, and migrated deep into the pore structure. It was thus concluded that the present chitosan–silicate hybrids were promising for tissue engineering scaffold applications.

In the brain after infarction or trauma, the tissue eventually becomes pannecrotic and forms a cavity. In such situations, a scaffold is necessary for the implanted or migrated cells to produce new tissue. In this present study, therefore, we attempted to restore brain tissue using a novel biomaterial, polydimethylsiloxane-tetraethoxysilane (PDMS-TEOS) hybrid with or without vascular endothelial growth factor (VEGF), which is crucial for new vessel formation. When PDMS-TEOS scaffold was implanted into the artificial brain defect, it remained at the implanted site and kept the integrity of the brain shape. At 30 days after the implantation, the marginal territory of PDMS-TEOS scaffold became occupied by newly formed tissue. Immunohistochemical analysis revealed that the new tissue was constituted by astrocytes and endothelial cells. Addition of VEGF increased the newly produced tissue volume, and the immunohistochemical analysis showed that the numbers of astrocytes and endothelial cells were increased. Double staining with proliferation maker Ki67 demonstrated that VEGF significantly increased newly formed astrocytes and endothelial cells, indicating that addition of VEGF accelerated tissue restoration and angiogenesis. These findings show that implantation of PDMS-TEOS scaffold with VEGF might be effective for treating old brain infarction or trauma.

With proper pre-treatment of the metal, well-crystallized thin anatase films of thicknesses varying from 0.12 to 0.79 μm were deposited on commercially available pure titanium (CPTi) substrate from a 25 mM titanium tetrafluoride aqueous solution. The deposition of anatase films took place at a low temperature of 60 °C between 1 to 48 h. After a heat treatment in air at 300 °C for 1 h to remove fluorine from the anatase films, the films of thicknesses above 0.41 μm induced apatite deposition in a simulated body fluid (SBF) within 5 days. The 0.12 μm thick anatase film required 21 days to induce apatite formation in SBF. There appeared to be a critical film thickness of anatase, above which the in vitro bioactivity improved greatly. But further increases in the film thickness of anatase did not have remarkable effect on in vitro bioactivity.

Surface modification of titanium implants by introducing a titania layer on their surface is an effective approach to provide bioinert titanium with bioactivity, i.e., the ability to bond directly and tightly to the surrounding hard tissue through the formation of a thin layer of apatite after implantation in the human body. The crystalline structure and abundance of Ti–OH functional groups have been found to contribute to the ability of titania gel to initiate apatite deposition on titanium in human physiological fluid. In the current investigation, an amorphous titania gel was firstly introduced on titanium surface by oxidizing the titanium substrate with hydrogen peroxide. Well-crystallized anatase films incorporated with abundant Ti–OH groups were then produced simply through a subsequent hot water aging of the amorphous titania gel. Results obtained in this investigation suggested that the low-temperature crystallization of titania proceeded in a dissolution–precipitation process. Titanium treated by the present low-temperature chemical modification technique induced significant apatite deposition within 24 h in a simulated body fluid (SBF).

Much interest has recently been shown in the potential utility of bioartificial liver (BAL) as a bridge support for patients and as a module for experimental purposes. A radial-flow bioreactor (RFB), one of the perfused bed/scaffold-type bioreactors, enables a highly functional three-dimensional culture as BAL. The functional capacity of bioreactors depends not only on their mechanistic structures but also on scaffolds packed in them. In the present study, we examined the possible utility of a new porous organic-inorganic-hybrid scaffold in an RFB. The scaffold was made from tetraethoxysilane (TEOS) and polydimethylsiloxane (PDMS) by a sol-gel method using sieved sucrose particles as a porogen. In the porous TEOS-PDMS hybrid scaffold, human hepatocellular carcinoma cells (HepG2) proliferated actively and formed cell clusters more efficiently than they did in a polyvinyl-alcohol scaffold. When cultivated in PDMS-TEOS, HepG2 cells secreted a approximately three-fold greater amount of albumin than that secreted in a monolayer culture. For potential application of BAL to pharmacological studies and future clinical use, it is essential to develop a method to propagate liver cells that maintain highly specific functions. The present results indicate that PDMS-TEOS may be a promising scaffold for developing such functional culture methods.

Chitosan-silicate hybrids were synthesized using γ-glycidoxypropyltrimethoxysilane (GPSM) as the agent for cross-linking the chitosan chains. CaCl2 was introduced in the hybrids in expectation that it would improve cell adhesion and differentiation of the hybrid surfaces. Fourier-transform infrared (FT–IR) spectroscopy and 29Si CP-MAS NMR spectroscopy were used to analyze the structures of the hybrids. Cytocompatibility of the hybrids was investigated in terms of proliferation of an osteoblastic cell line, MG63. The adhesion and proliferation of the osteoblastic cells cultured on the surface of a chitosan-GPSM hybrid without calcium were similar to those on a control culture plate, and were better than those on a chitosan membrane. The ALP activity of the cells cultured on this hybrid was higher than that on the chitosan membrane. Contrary to expectations, the incorporation of calcium ions into the hybrids did not improve cell attachment and proliferation on their surfaces.

Hyaluronic acid (HyA) and zinc carboxylate gels were synthesized by using L-malic acid (MA) and NaOH solutions. Obtained gels (HyA/Zn/MA gels) had a characteristic with transparency of 12.9 to 48.2% at a wavelength of 500 nm, pH values ranging from 6.8 to 7.1. The polymerization reaction and the formation of network structure were completed within 12 h. Rheological measurements indicated that the storage (G′) moduli were higher than the loss (Gʺ) moduli in all specimens and the elastic moduli were greater than 10,000 Pa, which is higher than gels cross-linked with covalent bonds. Moreover, gel strength values (S calculated from the complex (G*) moduli at 1.0 Hz) were higher than other chemically cross-linked gels. The gel strength increased at zinc concentrations up to 0.45 mol/l, however, decreased at a zinc concentration of 0.5 mol/l with an increasing HyA concentration. The rheological properties of HyA/Zn/MA gels strongly depended on zinc and HyA concentrations.

We prepared an organotitanium molecular layer on stainless-steel (SUS316L) substrates, and evaluated its blood compatibility in terms of blood-clotting time and fibrinogen adsorption properties. Titanium methacrylate triisopropoxide (TMT) was used as the organotitanium molecule. The surface was characterized by contact angle measurement toward distilled water and Fourier transform infrared spectroscopy using a reflection absorption method (FT-IRRAS). The obtained organotitanium molecular layer had little effects on the blood-clotting times such as active partial thromboplastin time (PTT) and prothrombin time (PT). Bovine fibrinogen adsorption on the layer was examined from the absorbance of amide I peak in FT-IRRAS spectra. The organotitanium molecular layer reduced the amount of adsorbed fibrinogen compared with stainless-steel.

Zinc/malic acid (Zn/MA) carboxylate gels were synthesized by adding a NaOH solution to solutions containing ZnCl2 and MA at room temperature, without adding a NH4OH solution. Glassy hydrogels with the transparency of 20.0–88.2% and with high viscosity were produced by a polymerization reaction in which the carboxyl and hydroxyl groups of MA were directly chelated by zinc ions. The gelation occurred in a narrow pH range as well as a narrow zinc concentrations range at 0.5 mol/l MA concentration. The Raman spectra showed that a new Raman line appeared at 881 cm−1 and we assigned it to the Zn–O–Zn vibration, and a red shift of the carboxyl and hydroxyl groups of MA. Rheological measurement showed the highest values of the storage and loss modulus when pH of the solution was raised to 7.0, and that the increase in the zinc ion concentration increased the storage and loss modulus increased due to the greater density of chelation. The linear correlation of log (G∗) and log (ω) indicated that the glassy hydrogels had a gel-like three-dimensional network.

The correlations between titanium oxide layers on oxidized titanium (Ti) substrates and platelet adhesion were examined. Ti substrates were prepared by three different oxidation methods: the first one was treated with hydrogen peroxide (H2O2) solution, the second one was heated in air at moderate temperatures, and the third one was processed with both H2O2 and heating. The titanium oxide layers formed on the Ti substrates were characterized by wettability, chemical composition, thickness, and crystal phase. The platelet adhesion on these oxide layers was examined and correlated to the characterizations of the surface layers. The number of adhesive platelets seemingly correlated with the contact angle towards distilled water, because the number increased close to 70-80 degrees of the contact angle. The effect of surface oxidation on platelet adhesion was examined in detail and it was found that the composition and thickness of the oxide layer influenced platelet adhesion rather than wettability. Thick titanium oxide layers formed on Ti substrates by heating displayed less platelet adhesion than thin oxide layers on untreated Ti substrates. The largest number of adhesive platelets was found on H2O2-oxidized substrates; the substrates found on amorphous titanium oxide contained the Ti-peroxide radical species. The number of platelets, on the other hand, could hardly be observed on Ti substrates treated with H2O2 and subsequently heated above 300 degrees C. The titanium oxide layer on the substrate was thick and we found it to consist of only a few radical species. That is, the effect of heat treatment accelerates the growth of the oxide layer, and decomposes or decreases the number of radical species. Ti substrates with H2O2 and heat treatment above 300 degrees C held the least number of platelets, and were concluded to be the most inhibitory for platelet adhesion.

Thin titania film consisting of anatase and rutile was deposited on Ti substrates when soaked in a TiOSO 4 /H 2 O 2 solution and aged in hot water. H 2 O 2 corroded the Ti substrates, yielded a porous surface, and kept the solution from peptization. Thicker titania layers were formed in favor of both a greater supersaturation of Ti(IV) in the solution and a higher concentration of hydrated Ti(IV) derived by the corrosion of Ti and the hydrolysis of TiOSO 4 . The effects of aging in hot water were accounted for as they caused structural relaxation of the surface layer involving a rearrangement of Ti–OH and eliminating residual species like peroxide ions. Those titania layers were thus favored to deposit apatite when the Ti substrates were placed under a body environment, i.e. soaked in a simulated body fluid of Kokubo's recipe.

Chitosan/hydroxyapatite (HAp) composites have been prepared using a co-precipitation method. According to TEM observations, chitosan molecules formed nano-particles of 250×50 nm in size with small HAp crystals. The particles aggregated and the precipitates were reached a maximal size (17 μm) at a chitosan content of 25 wt.%, where the ζ-potential was around zero. This means that the precipitate size increased with a decrease in ζ-potential, i.e. electrostatic repulsion between the nano-particles. The precipitate size decreased at chitosan contents higher than 25 wt.% with excess chitosan molecules covering the nano-particles, resulting in a repulsion force between positively charged particles. When citric acid was added to a suspension of chitosan/HAp composite, the precipitates increased in size. Although, when citric acid was added to a pure HAp suspension, the citric acid showed no effect on the size. This finding suggests that citric acid affects chitosan rather than the HAp, through the formation of an ionic complex. This size effect has been found at citric acid contents lower than 3 wt.%. The precipitates have been compressed into a cylindrical shape under a uni-axial pressure, the compressive strength increased with increasing citric acid content. The composition of the maximal compressive strength agreed well with that of the maximal precipitate size.

Porous and bioactive gelatin–siloxane hybrids were successfully synthesized by using a combined sol–gel processing, post-gelation soaking, and freeze-drying process to provide a novel kind of materials in the developments and optimization of bone tissue engineering. The pore sizes of the hybrids can be well controlled by varying the freezing temperature. The scaffolds were soaked in a simulated body fluid (SBF) up to 14 days to evaluate the in vitro bioactivity. The Ca2+-containing scaffolds showed in vitro bioactivity as they biomimetically deposited apatite, but the Ca2+-free scaffolds failed. Cytotoxicity and cytocompatibility of those scaffolds and their extracts were monitored by the MC3T3-E1 cell responses, including the cell proliferation and the alkaline phosphatase activity. It was demonstrated that appropriate incorporation of Ca2+ ions stimulated osteoblast proliferation and differentiation in vitro.

Well-crystallized anatase films were deposited on commercially available pure titanium substrates from an acid titanium tetrafluoride aqueous solution kept at 60 °C for 24 h. The anatase films consisted of dual layers that were different in topography: a dense inner layer strongly adhered to the Ti substrate and a porous outer layer. In vitro bioactivity of such films was evaluated by soaking them in a simulated body fluid (SBF) of the Kokubo solution to observe their ability to induce apatite deposition. The anatase films with a subsequent thermal treatment at a temperature range of 300–700 °C induced apatite deposition within 5 days. Apatite particles were also found to deposit within 7 days on the anatase films being heated at 800 °C, which involved much rutile due to direct air oxidation of the titanium substrate. When the heating temperature is lower than 200 °C, no apatite deposited on the films even after 10 days of soaking in the SBF solution. The improved in vitro bioactivity of the films subsequently heated over 300 °C was attributed to the elimination of fluorine.

Titania films with crystal structures of anatase or a mixture of anatase and rutile were prepared through a soft solution approach. The crystalline titania film resulted from crystallization of the previously deposited amorphous gel in an acidic solution. A low pH value of the solution favored the formation of rutile.

We synthesized organically modified silicate (ORMOSILs) gels with colloidal silica (CS) (AEROSIL®) starting from polydimethylsiloxane (PDMS), tetraethoxysilane (TEOS) and calcium nitrate (Ca(NO 3 ) 2 ·4H 2 O) through sol–gel processing. Dynamic mechanical analysis indicated that relative height of the tan δ peak at about −100 °C increased with an increase in the relative content of the inorganic components. This peak growth was accounted for by the relative increase in PDMS–colloidal silica particle interactions. The colloidal silica could control the mechanical behavior of the hybrids. The gel of a specific composition could deposit apatite within 3 days of soaking in the simulated body fluid (SBF), since it included many calcium ions on the surface.

Anatase films with sub-micron porous structure were deposited homogeneously on Ti substrates by simply soaking in 15 wt.% hydrogen peroxide solution at 80 °C for 1 h followed by heating at 300 °C for 1 h in air. Deposition of the porous titania film was not sensitive to substrate morphology, whilst affected readily by the reaction rate.

Ca(II) containing porous hybrids of gelatin and 3-(glycidoxypropyl)trimethoxysilane (GPSM) were prepared using a sol–gel process, post-gelation soaking, and freeze-drying. The porosity and pore size of the hybrids could be well controlled by the freezing temperature and the pH value of the soaking solution. The pore characteristics were related to the structure change during the soaking treatment. A second soaking of the porous hybrids introduced a binary-pore distribution. The rate of biodegradation in a trishydroxymethylaminomethane (Tris) buffer solution decreased with an increased GPSM content. A bone-like apatite layer was able to form in the Ca(II) containing porous gelatin–siloxane hybrids upon soaking in a stimulated body fluid (Kokubo recipe). These hybrid materials are proposed to find application as novel bioactive and biodegradable scaffolds in bone tissue engineering.

Titanium and its alloys are employed as artificial joints, bone plates, wires, screws and bone prostheses in orthopedic and dental fields, because of their high corrosion resistance, good mechanical properties, and biocompatibility. Since they cannot directly bond to living bone–tissue through stable chemical interactions, a few surface modification techniques have been proposed for giving materials apatite-forming ability that secures bone–tissue bonding, such as chemical treatment with H 2 O 2 or NaOH, electrochemical oxidation, electrophoretic apatite particle deposition, and UV-irradiation of surface titanium oxide layer. This study examined how the combination of H 2 O 2 chemical treatment and UV-irradiation affected in vitro apatite-formation on TiO 2 (anatase phase) layers as UV was irradiated under a few different conditions. TiO 2 layer was prepared by the chemical treatment with H 2 O 2 solution and subsequent heat-treatment (CHT). CHT samples were irradiated with UV-light for 1 h in air or in ultra-pure water. They were then soaked in Kokubo's simulated body fluid (SBF; pH 7.4) at 36.5 °C for 1 day. Their surface structure and morphology were examined by using a thin film X-ray diffractometer (TF-XRD), and a scanning electron microscope (SEM). The UV-irradiation of CHT in air reduced the number of active sites for apatite nucleation. On the contrary, however, the UV-irradiation in water increased them. These opposite results indicate that environmental factors of the UV-irradiation are important for controlling the in vitro apatite-forming ability of anatase layer.

X-ray photoelectron (XPS) and 29Si magic angle spinning (MAS)-NMR spectroscopy have been used to examine the chemical states of fluorine, oxygen, silicon and lead atoms in the glasses of composition x PbF 2 ·(100−y−x) PbO ·y SiO 2 (x=0,5,10,15,20,30 mol%, y=30,50,60 mol%). The analysis of the F 1s spectra indicated that Pb2+ and F− ions are preferentially located among the Si–O skeleton forming ionic Pb–F clusters. The fraction of the bridging (BO) and non-bridging oxygen (NBO) atoms was derived from the O 1s spectra. The network of the fluorine-containing glasses was concluded to depend on the ratio PbO/SiO2; when the ratio PbO/SiO2 was lower than 0.5, not only Pb atoms but also F atoms play a role as network modifiers, while when the ratio PbO/SiO2 is higher than 1.33, part of Pb atoms plays a role as a glass network former.

Chemical states of fluorine in fluorosilicate glasses in the system MF2-MO-SiO2 (M = Ca, Sr and Ba; SiO2 content < 60 mol%) have been investigated by molecular dynamic (MD) simulations with a perfect ionic two-body potential. Comparison of the results with those derived by X-ray photoelectron spectra of the actual glasses demonstrates that MD simulations reproduce well the bonding states of fluorine in the systems as well as the formation of M-F clusters. The MD generated structure of imaginary glasses, or glasses not obtained by the conventional melt-quench technique, with 70 mol% SiO2 indicates that an acidic environment induces a greater amount of FSi bonds. Their M-F pair correlation functions plotted against normalized M-F distances suggest that relative ion positions in the clusters are very similar.

Wavelet analysis of X-ray diffraction patterns was made for structures of silica glasses manufactured by electrical fusion, oxy-hydrogen flame fusion of quartz powder, and flame hydrolysis of SiCl4. The analysis indicates that their structures were not affected by the manufacture methods. It is believed that there is a thermodynamically most favoured or unique structure for glass in an intermediate range up to a few nm. It is expected that amorphography (in analogy to crystallography for crystal) for glass will emerge as a new branch of science. According to our statistical crystallite model, glass structure could be determined by the crystallography of corresponding crystals and the damping with interatomic distance for the crystalline regularity.

X-ray photoelectron spectra of R2OTeO2 (R: Li, Na, K, Rb and Cs) glasses were measured, using a fresh surface fractured in an ultra high vacuum (≈ 7 × 10−8 Pa) and irradiated with a monochromatic Al K α X-ray (hv = 1486.6 eV). The O ls photoelectron spectra showed only a single Gaussian-Lorentzian peak and the peak shifted toward smaller binding energy with increase in Lewis basicity of oxide ions in the glasses. Two peaks attributed to BO and NBO were not observed. In the near valence band spectra for the lithium tellurite glasses, the spectral profile gradually became similar to that of a Li2TeO3 crystal with increase in Li2O content up to 30 mol% Li2O. This variation of the profile is correlated to the change in the coordination structure of the tellurium atoms (TeO4 trigonal bipyramids → TeO3 trigonal pyramids) with the addition of the alkali oxides.