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A coherent receiver that can demodulate high-speed in-phase and quadrature signals of light is an essential component for optical communication, interconnects, imaging, and computing. Conventional waveguide-based coherent receivers, however, exhibit large footprints, difficulty in coupling a large number of spatial channels efficiently, and limited operating bandwidth imposed by the waveguide-based optical hybrid. Here, we present a surface-normal coherent receiver with nanometallic-grating-based polarizers integrated directly on top of photodetectors without the need for an optical hybrid circuit. Using a fabricated device with the active section occupying a 70-{\mu}m-square footprint, we demonstrate demodulation of high-speed (up to 64 Gbaud) coherent signals in various formats. Moreover, ultra-broadband operation from 1260 nm to 1630 nm is demonstrated, thanks to the wavelength-insensitive nanometallic polarizers. To our knowledge, this is the first demonstration of a surface-normal homodyne optical receiver, which can easily be scaled to a compact two-dimensional arrayed device to receive highly parallelized coherent signals., Comment: 23 pages, 4 figures (main manuscript) + 4 pages, 2 figures (supporting info)

To develop one porous additive material that can be assembled on cigarette filter, and achieve both functions of reducing hazard substances like tar and providing special aroma and moisture, this study innovatively selects the raw materials like baking-carbonized functional flavors with special aroma and konjac glucomannan (KGM) with properties of water absorption, gelling and film-forming, following the steps of casting into membrane shape, thermostatic crosslinking for strength enhancement and freeze-drying for pore creating to prepare 5 porous composite membranes based on baked-carbonized functional flavors and konjac glucomannan (KGM) were prepared. The composite structure, morphologies on the surface and the cross section, porosity structures including mesoporous and macropore of the porous composite membranes were characterized, the tensile performance and aroma constituents through solid phase microextraction and hazardous substances adsorption as packed into the commercial cigarette were also studied. Results showed that all baked-carbonized functional flavors were carbonized into amorphous, and contained the groups of aromatic components like ≡C-H, C=O, C-O-C (aldehydes, esters), cross-linking achieved the entanglement of KGM segments by deacetylation. When compounded, KGM acted as the framework to build the 3D porous network structure, and the functional flavor powders were wrapped into the KGM layer. All porous composite membranes owned some mechanical strength and the internal porosity over 90%, the mesopores and the macropores were ranged with 5–50 nm and 20–255 µm, respectively, which was satisfied for gas flowing and harmful substances adsorption. Aroma and resulting abundance of extracted constituents changed with timing, which equipped the membranes with a comprehensive aroma feeling. Among them, the membrane prepared with the raw material of dark plum showed a better comprehensive performance, especially it could significantly reduce the contents of harmful HCN and phenol in cigarette during smoking.

Fluorapatite exhibits improved bone-bonding and chemical durability under neutral and acidic conditions compared with hydroxyapatite. Typically, an aqueous fluoride solution is used for F− incorporation into the hydroxyapatite. Use of an ionic liquid as F− source provides highly-concentrated ionic environment and can lead to more effective fluorination. In this study, two ionic liquids were added during the synthesis of hydroxyapatite under various conditions, and the differences in the crystalline structure and chemical durability of the resulting fluorapatites were investigated. 1-ethyl-3-methylimidazolium tetrafluoroborate was quite effective for F− incorporation, but not 1-ethyl-3-methylimidazolium hexafluorophosphate. When the temperature was increased to 80 °C, not only the hydroxyapatite or fluorapatite but also CaF2 was generated as a by-product. When the initial pH was decreased to 7, the formed product fully converted to CaF2. The solubility of the product tended to be suppressed in acidic conditions with increase in amount of fluorine substituted in the crystal lattice.

BACKGROUND: Microbeads for bone repair have been widely studied because they can be conveniently used in clinical applications. OBJECTIVE: This study concerns the preparation, physical properties and in vitro characterisation of different types of alginate/calcium phosphate (CaP) ceramic microbeads, which were designed for use as drug delivery systems and bone-regeneration matrices. METHODS: Hybrid microbeads were successfully prepared from sodium alginate and various CaP, namely 𝛼-tricalcium phosphate, 𝛽-tricalcium phosphate and hydroxyapatite using the liquid droplet method. RESULTS: Porosity, swelling properties and in vitro degradation of the microbeads in the aqueous environment were significantly changed by the added CaP. The compressive strength of the blocks fabricated from the beads was around 120 MPa irrespective of the type of CaP. The initial release rate of the model drug methylene blue was suppressed by the addition of CaP. CONCLUSION: The alginate-CaP composite beads hold promising potential as an encapsulation carrier of drugs and component of bone substitutes.

Bioactivity modification helps polymethylmethacrylate (PMMA) bone cement to reinforce its interfacial adhesion to bone tissues through the chemical bonding of apatite. Since Si-OH groups combined w...

Tolvaptan is an orally active vasopressin V

Octacalcium phosphate (OCP) is a key precursor of biological apatite in hard tissues with excellent osteoconductive and biodegradable properties for bone regeneration. OCP spherical granules are expected to be useful as drug delivery carriers, since OCP has high specific surface area. Although there have been some reports of OCP sphere preparation, methods for preparing pure OCP spheres are limited. The objective of this study is the preparation of spherical granules of pure OCP and assessment of their in vitro biodegradation in physiological conditions. We successfully prepared spherical pure OCP granules with a size of ~500 µm without any organic additives by simple immersion of α‐tricalcium phosphate spherical granules in pH 5.0 acetate buffered solutions at 60°C. The granules had core‐shell structure composed of OCP crystals different particle size. The spherical granules showed 20%‐40% in vitro degradation in physiological conditions; however, the phase transition of OCP was not significantly observed.

Magnetic iron oxides such as magnetite and γ-hematite have attracted considerable attention as thermoseeds for hyperthermia treatment because of their ability to generate heat under an alternating magnetic field. Control of the particle size and their combination with biocompatible polymers are expected to be beneficial for optimization of the nanoparticles. These processes can be accomplished through the synthesis of magnetite in gels, as the network structure of the polymer gel can control the grain growth of the magnetite. However, the effect of the cross-linking density of the gels remains unclear. In this study, we synthesized magnetic iron oxides in situ in chitosan hydrogels with different cross-linking densities and examined the crystalline structure and heat generation under alternating magnetic field. The crystalline phase and amount of magnetite were observed to be dependent on the cross-linking density of the gel, and the heat generation of the nanoparticles was governed by their crystalline structure and particle size rather than solely the amount of formed iron oxide.

Octacalcium phosphate (OCP), an encrusted calcium phosphate complex, has appealed consideration in the field of biomaterial and apothecary, owing to its exceptional biocompatibility. However, not much is known about the effect of Na ion for the formation of OCP, irrespective of pH. Consequently, in this study, we considered the part of the Na ion in OCP growth from dicalcium phosphate dihydrate (DCPD) via hydrolysis by using 0.1 M CH3COONa solutions with adjustment of various pH. Novelty of the study is, expending this way we can synthesize OCP irrespective of pH and most importantly at 37°C, which is an important parameter for acceptable biomaterials. Throughout the study, no foreign phase was observed except OCP. Morphological images are also evident for the attractive OCP flowers.

Artificial hydroxyapatite (HAp) is osteoconductive, but the mechanism is still unclear. It is likely that some serum proteins are adsorbed onto HAp and influence its osteoconductivity. We investigated the adsorption behavior of laminin (LN), which was isolated from murine Engelbreth–Holm–Swarm sarcoma, onto HAp and compared it with nonosteoconductive alpha-type alumina (α-Al2O3). Cell adhesion, spreading, and proliferation on native and LN-adsorbed discs of HAp or α-Al2O3 were examined using murine MC3T3-E1 osteoblastic cells. A larger amount of LN adsorbed onto HAp than α-Al2O3 despite the electrostatic repulsion between LN and HAp, suggesting the specific adsorption of LN onto HAp. The LN adsorbed onto HAp remarkably enhanced initial attachment and spreading of MC3T3-E1 cells, but subsequent proliferation of MC3T3-E1 cells was influenced by the type of material rather than LN adsorption. These fundamental findings imply that LN adsorbed on HAp could trigger osteoconductivity in vivo, aiding in the development of novel biomaterials that specifically adsorb LN and effectively enhance cell attachment and spreading.

Magnetite (Fe3O4) nanoparticles such as thermoseeds for hyperthermia and contrast media in magnetic resonance imaging are attracting increasing attention in biomedicine. The organic modification of nanoparticles is an important technique to improve the biological compatibility and drug delivery functions. Also, the addition of organic molecules and the use of hydrogels as a reaction field in Fe3O4 preparation enable controlling the crystalline phase and particle size. In this chapter, the organic modification of Fe3O4 nanoparticles for biomedical applications is reviewed.

Bioactivity modification helps polymethylmethacrylate (PMMA) bone cement to reinforce its interfacial adhesion to bone tissues through the chemical bonding of apatite. Since Si-OH groups combined with Ca

Ti–Zr alloys are expected to be novel biomaterials with low stress shielding owing to their lower Young’s moduli than pure Ti. The drawback of metallic biomaterials is that their bone-bonding abilities are relatively low. NaOH and heat treatments have been performed to provide Ti–50Zr with apatite-forming ability in the body environment, which is essential for bone bonding. However, the systematic compositional dependence of apatite formation has not been revealed. In the present study, NaOH treatment of Ti–Zr alloys with various compositions and bone-bonding abilities was assessed in vitro by apatite formation in simulated body fluid (SBF). The corrosion current density in NaOH aqueous solution and the amount of Na incorporated into the surface tended to decrease with increasing Zr content. The apatite-forming ability of the treated alloy significantly decreased when the Zr content was ≥60 atom%. This phenomenon is attributed to the (1) low OH content on the surface, (2) low Na incorporation into the treated alloy surface, which enhances apatite formation, and (3) low ability of P adsorption to the Ti–Zr alloy in SBF following Ca adsorption to trigger apatite nucleation. Although the adhesion of the titanate/zirconate layer formed on the surfaces to the substrates increased as Zr content increased, the adhesion between the apatite and the substrate was still low.

Organic-inorganic composites are novel bone substitutes that can ameliorate the mismatch of Young's moduli between natural bone and implanted ceramics. Phosphate groups contribute to the formation of apatite in a simulated body fluid (SBF) and the adhesion of osteoblast-like cells. Therefore, modification of a polymer with these functional groups is expected to enhance the ability of the organic-inorganic composite to bond with bone. Two phosphate groups have been used, phosphonic acid (-C-PO

Organic–inorganic composites are novel bone substitutes that can ameliorate the mismatch of Young's moduli between natural bone and implanted ceramics. Phosphate groups contribute to the formation of apatite in a simulated body fluid (SBF) and the adhesion of osteoblast-like cells. Therefore, modification of a polymer with these functional groups is expected to enhance the ability of the organic–inorganic composite to bond with bone. Two phosphate groups have been used, phosphonic acid (–C–PO3H2) and phosphoric acid (–O–PO3H2). However, the effects of structural differences between these phosphate groups have not been clarified. In this study, the apatite formation of copolymers modified with Ca2+ and either –C–PO3H2 or –O–PO3H2 was examined. The mechanism of apatite formation is discussed based on analytical and computational approaches. The copolymers containing –O–PO3H2, but not those containing –C–PO3H2, formed apatite in the SBF, although both released similar amounts of Ca2+ into the SBF. Adsorption of HPO42− from –O–PO3H2 in the SBF following Ca2+ adsorption was confirmed by zeta-potential measurement and X-ray photoelectron spectroscopy. The measurement of the complex formation constant revealed that the –O–PO32−⋯Ca2+ complex was thermodynamically unstable enough to convert into CaHPO4, which was not the case with –C–PO32−⋯Ca2+. The formation of CaHPO4-based clusters was found to be a key factor for apatite nucleation. In conclusion, this study revealed that modification with –O–PO3H2 was more effective for enhancing apatite formation compared with –C–PO3H2.

Hafnium (Hf) has attracted considerable attention as a component of biomedical titanium (Ti) alloys with low Young's moduli and/or shape-memory functionalities, because its cytotoxicity is as low as that of Ti. The drawback of metals is that their bone-bonding ability is generally low. It is known that apatite formation in the body is a prerequisite for bone-bonding. Although several chemical treatments have been proposed for preparing Ti for bone-bonding, there have been no similar investigations for Hf. In the present study, NaOH- and heat-treatments were applied to pure Hf and Ti-Hf alloys and their bone-bonding ability was assessed in vitro with the use of simulated body fluid (SBF). After NaOH- and heat-treatments, anatase formed on alloys with low Hf content (20-40% (atom%) Hf); mixtures of sodium titanate and hafnium titanate formed on alloys with similar Ti and Hf content (60% Hf); and hafnium oxide formed on alloys with high Hf content (80% Hf and pure Hf). Precipitates of apatite were observed on all the metals in SBF, except for the alloy with 60% Hf. We speculated that the hafnium titanate formed on this alloy had a low apatite-forming ability owing to its high negative surface charge, which inhibited P adsorption. The apatite-forming abilities of the Ti-Hf alloys strongly depended on their Hf content. The present results indicate that Hf-based materials have good potential for bone-bonding. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2519-2523, 2018.

Polyetheretherketone (PEEK) has attracted much attention as an artificial intervertebral spacer for spinal reconstruction. Furthermore, PEEK plastic reinforced with carbon fiber has twice the bending strength of pure PEEK. However, the PEEK-based materials do not show ability for direct bone bonding, i.e., bioactivity. Although several trials have been conducted for enabling PEEK with bioactivity, few studies have reported on bioactive surface modification of carbon–PEEK composites. In the present study, we attempted the preparation of bioactive carbon-PEEK composites by chemical treatments with H 2 SO 4 and CaCl 2 . Bioactivity was evaluated by in vitro apatite formation in simulated body fluid (SBF). The apatite formation on the carbon–PEEK composite was compared with that of pure PEEK. Both pure PEEK and carbon-PEEK composite formed the apatite in SBF when they were treated with H 2 SO 4 and CaCl 2 ; the latter showed higher apatite-forming ability than the former. It is conjectured that many functional groups able to induce the apatite nucleation, such as sulfo and carboxyl groups, are incorporated into the dispersed carbon phase in the carbon–PEEK composites.

Magnetic microspheres measuring 15-35 µm in diameter are believed to be useful for intra-arterial hyperthermia. In this study, we attempted to prepare titanium dioxide (TiO2 ) microspheres containing magnetic nanoparticles (MNPs). MNP-containing TiO2 microspheres with diameters of approximately 30 µm were successfully obtained by sol-gel reaction of titanium tetraisopropoxide in a water-in-oil emulsion with added cosurfactant of 1-butanol and subsequent heat treatment at 200°C. The microspheres showed ferrimagnetism owing to high content of MNPs in approximately 60 wt % and had a low-crystalline TiO2 matrix. Furthermore, the agar phantom was heated to above 43°C after approximately 1 min under an alternating magnetic field of 100 kHz and 300 Oe and showed in vitro biocompatibility similar to that of MNP-free TiO2 microspheres. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2308-2314, 2017.

Biofilm formation of periodontal pathogens on teeth surfaces promotes the progression of periodontal disease. Hence, understanding the mechanisms of bacterial attachment to the dental surfaces may inform strategies for the maintenance of oral health. Although hydroxyapatite (HA) is a major calcium phosphate component of teeth, effect of biofilm formation on HA surfaces remains poorly characterized. In this study, biofilm-forming abilities by the periodontal pathogens Aggregatibacter actinomycetemcomitans Y4 and Porphyromonas gingivalis 381 were investigated on dense and porous HAs that represent enamel and dentin surfaces, respectively. These experiments showed greater biofilm formation on porous HA, but differing attachment profiles and effects of the two pathogens. Specifically, while the detachment of A. actinomycetemcomitans Y4 biofilm was observed, P. gingivalis 381 biofilm increased with time. Moreover, observations of HA morphology following formation of A. actinomycetemcomitans Y4 biofilm revealed gaps between particles, whereas no significant changes were observed in the presence of P. gingivalis 381. Finally, comparisons of calcium leakage showed only slight differences between bacterial species and HA types and may be masked by bacterial calcium uptake. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2873-2880, 2016.

Natural bone consists of apatite and collagen fiber. Bioactive materials capable to bonding to bone tissue are clinically used as bone-repairing materials. Apatite-organic polymer composites exhibit bone-bonding abilities and mechanical properties similar to those of natural bone, and these materials can be prepared using biomimetic processes in simulated body fluid (SBF). Specific functional groups such as sulfonic and carboxylic acid groups are known to induce the heterogeneous nucleation of apatite in SBF. However, it remains unclear whether structurally related sulfinic acid groups can contribute to apatite formation in the same way, despite sodium sulfonate being used in biomedical applications as a radical polymerization promoter in adhesive dental resin. Herein, we report the preparation of a new hydrogel containing sulfinic acid groups from sodium 4-vinylbenzenesulfinate and 2-hydroxyethyl methacrylate using a radical polymerization reaction and the subsequent incorporation of Ca2+ ions into this material. We also investigated the apatite-forming behavior of these hydrogels in SBF. Hydrogels containing sulfinic acid groups showed higher apatite-forming ability than those without sulfinic acid groups. In addition, the apatite layer formed on the former showed tight adhesion to the hydrogel. This phenomenon was attributed to the heterogeneous nucleation of apatite, induced by the sulfinic acid groups. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1924-1929, 2017.

Magnetite (Fe 3 O 4 ) nanoparticles and magnetite-based inorganic–organic hybrids are attracting increasing attention in biomedicine, as thermoseeds for hyperthermia and contrast media in magnetic resonance imaging. Controlling the size of Fe 3 O 4 thermoseeds is important, as particle size affects their heat generation under alternative magnetic fields. Fe 3 O 4 is easily synthesized via aqueous processes. We previously demonstrated that adding organic polymers during synthesis affected the size and crystallinity of the resulting Fe 3 O 4 . However, the relationship of the chemical structure of the low-molecular-weight organic additive of its effect on the product has not been elucidated. In this study, organic compounds containing varying functional groups and surface charges were added to the precursor solution of Fe 3 O 4 . Crystalline Fe 3 O 4 formed in the presence of neutral acetone, cationic ethylenediamine, and anionic acetic acid. These nanoparticles had slightly smaller particle sizes than those prepared in the absence of additives. The presence of oxalic acid and tris(hydroxymethyl)aminomethane inhibited Fe 3 O 4 nucleation, instead yielding lepidocrosite- or akaganeite-type FeOOH. These differences were attributed to the ability to form complexes between iron ions and the organic additives. The saturation magnetizations of the products were consistent with Fe 3 O 4 . This indicated that the crystal phase of the iron oxide products differed, even when prepared in the presence of organic additives of the same functional group. It is concluded that state of ion-organic molecule complex in the solutions is a key factor governing nanostructure of the resultant iron oxide.

Bone cement from polymethylmethacrylate powder and methylmethacrylate liquid has been successfully demonstrated as artificial material to anchor joint replacements in bone. However, it lacks the capability to bond directly to bone, so long-term implantation leads to an increased risk of loosening. Bioactive materials show better performance in fixation to bone, and the chemical bonding depends on bone-like apatite formation. This is triggered by surface reactions with body fluid. For these reactions, superficial functional groups like silanol (Si–OH) are ideal sites to induce apatite nucleation and the release of Ca2+ ions accelerates the apatite growth. Therefore, incorporation of materials containing these key components may provide the cement with apatite-forming ability. In this study, phosphoric acid 2-hydroxyethyl methacrylate ester or bis[2-(methacryloyloxy)ethyl] phosphate supplying a phosphate group (PO4H2) was added into methylmethacrylate liquid, while calcium acetate as a source of Ca2+ ions was mixed into polymethylmethacrylate powder. The influences of the combinations on the setting time and compressive strength were also investigated. Apatite was formed on the cements modified with 30 mass% of phosphoric acid 2-hydroxyethyl methacrylate ester or bis[2-(methacryloyloxy)ethyl] phosphate. The induction period was shortened with increased amounts of Ca(CH3COO)2. The setting time could be controlled by the Ca(CH3COO)2/monomer mass ratio. Faster setting was achieved at a ratio close to the mixing ratio of the powder/liquid (2:1), and both increases and decreases in the amount of Ca(CH3COO)2 prolonged the setting time based on this ratio. The highest compressive strength was 88.8 ± 2.6 MPa, higher than the lowest limit of ISO 5833 but was lower than that of the simulated body fluid-soaked reference. The increase of additives caused the decline in compressive strength. In view of balancing apatite formation and clinical standard, bis[2-(methacryloyloxy)ethyl] phosphate is more suitable as an additive, and the optimal modification is a combination of 30 mass% of bis[2-(methacryloyloxy)ethyl] phosphate and 20 mass% of Ca(CH3COO)2.

Although titanium (Ti) is clinically used for hard tissue reconstruction, it has low bone-bonding ability, i.e. bioactivity. Materials able to deposit apatite on their surfaces within the body is considered to exhibit bioactivity. Effects of the metallographic structure and machining process of Ti on its apatite-forming ability remains unclear. In this study, Ti substrates subjected to various preheating and machining processes were then subjected to NaOH and heat treatments. The apatite-forming abilities of resulting Ti were examined in simulated body fluid (SBF). Preheating of the Ti decreased its reactivity with NaOH solution. When quenched or annealed Ti was subjected to NaOH and heat treatments, the induction period for apatite formation in SBF slightly increased. This was attributed to a decrease in sodium titanate and increase in rutile on the Ti surface after the treatments. Substrates subjected to wire-electrical-discharge machining did not form apatite. This was attributed to the inhibition of PO43- adsorption on their surfaces following Ca2+ adsorption, which is an essential process for apatite nucleation. Contamination of Ti surface by components of the brass wire used in the machining contributed to the inhibition. The bioactivity of surface-modified Ti was therefore significantly affected by its thermal treatment and machining process.

Hafnium (Hf) has attracted considerable attention as a component of biomedical titanium (Ti) alloys with low Young's moduli and/or shape-memory functionalities, because its cytotoxicity is as low as that of Ti. The drawback of metals is that their bone-bonding ability is generally low. It is known that apatite formation in the body is a prerequisite for bone-bonding. Although several chemical treatments have been proposed for preparing Ti for bone-bonding, there have been no similar investigations for Hf. In the present study, NaOH- and heat-treatments were applied to pure Hf and Ti-Hf alloys and their bone-bonding ability was assessed in vitro with the use of simulated body fluid (SBF). After NaOH- and heat-treatments, anatase formed on alloys with low Hf content (20-40% (atom%) Hf); mixtures of sodium titanate and hafnium titanate formed on alloys with similar Ti and Hf content (60% Hf); and hafnium oxide formed on alloys with high Hf content (80% Hf and pure Hf). Precipitates of apatite were observed on all the metals in SBF, except for the alloy with 60% Hf. We speculated that the hafnium titanate formed on this alloy had a low apatite-forming ability owing to its high negative surface charge, which inhibited P adsorption. The apatite-forming abilities of the Ti-Hf alloys strongly depended on their Hf content. The present results indicate that Hf-based materials have good potential for bone-bonding. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2519-2523, 2018.

Ceramic microspheres composed of β-emitters are useful for in situ radiotherapy of deep-seated cancer by implantation around the tumor. In addition, microspheres 20–30 µm in diameter can combine β-emission with the embolization effect. Yttrium phosphate is an attractive candidate material for such microspheres, because both Y and P play roles as β-emitters. The half-life of 31 P is known to be much larger than that of 90 Y. Therefore, it is expected that yttrium phosphate microspheres with high P content can maintain a longer radiotherapy effect. In the present study, preparation of microspheres with enriched P content has been attempted by water-in-oil emulsions using polyphosphate as a starting material. Yttrium phosphate microspheres with a higher P/Y molar ratio (2.5) than in previously reported YPO 4 microspheres were obtained. It was found that emulsification for sufficient time (more than 10 min) is necessary to obtain microspheres that are 20–30 µm in size. Although the microspheres released Y sparingly, they released larger amounts of P than previously reported YPO 4 microspheres in a simulated body environment. Heat treatment at moderate temperature can suppress P release to some extent. Further improvement in chemical durability through surface modification is essential for long-term clinical use.

In this study, we investigated the surface structure, apatite formation in simulated body fluid (SBF), and visible-light photocatalytic activity of Ti metal subjected to chemical and thermal treatments. Ti metal samples treated with NaOH, a nitrogen-containing solution (0.1 M HNO 3 , 0.1–1.0 M (H 2 N) 2 C O, or 0.1–1.0 M NH 4 Cl), and heat showed apatite formation on their surfaces in SBF, whereas those treated with NaOH, 0.5 or 1.0 M HNO 3 , and heat did not. In the former case, apatite formation may be attributable to the fine network structure of anatase-type TiO 2 doped with a small amount of nitrogen on the surface of the Ti metal. The Ti metal treated with the latter treatment showed higher methylene blue decomposition than the untreated sample and the one treated with the former treatment. This preliminary result suggests that Ti metal treated with NaOH, 0.1 M HNO 3 , and heat can potentially show visible-light-induced antibacterial property as well as bone-bonding ability.

Magnetite (Fe3O4) nanoparticles and magnetite-based inorganic–organic hybrids are attracting attention in biomedical fields as thermoseeds for hyperthermia and a contrast medium in magnetic resonance imaging. Size control of Fe3O4 thermoseeds is important as the particle size affects the heat generation properties. Fe3O4 can be easily synthesized via aqueous processes and the presence of organic substances during synthesis can affect the size and crystalline phase of the Fe3O4 formed. In this study, various polymers with different functional groups and surface charges were added to the precursor solution of Fe3O4 to clarify the relationship between the chemical structure of the organic substances and the crystal structure of Fe3O4. At first, coexistence effects of the organic substances in the solutions were clarified. As a result, crystalline Fe3O4 was precipitated even after addition of neutral polyethylene glycol and cationic poly(diallyldimethylammonium chloride). The poly(sodium-4-styrene sulfonate) addition significantly decreased the particle size, while polyacrylic acid addition inhibited Fe3O4 nucleation to afford an amorphous phase. These differences were related to the ease of complex formation from iron ions and coexisting organic polymers. In order to clarify this assumption, a modified experimental procedure was applied for the polyacrylic acid. Namely, the iron oxide precipitation by the NaOH solution was followed by the polyacrylic acid addition. Notably, Fe3O4 nucleation was not inhibited. Hence, the size and crystalline phase of the iron oxide prepared by the aqueous process were drastically affected by organic polymers.

Bone cement containing alumina particles with a specific crystalline structure exhibits the ability to bond with bone. These particles (AL-P) are mainly composed of delta-type alumina (δ-Al2O3). It is likely that some of the proteins present in the body environment are adsorbed onto the cement and influence the expression of its bioactivity. However, the effect that this adsorption of proteins has on the bone-bonding mechanism of bone cement has not yet been elucidated. In this study, we investigated the characteristics of the adsorption of bovine serum albumin (BSA) onto AL-P and compared them with those of its adsorption onto hydroxyapatite (HA), which also exhibits bone-bonding ability, as well as with those of adsorption onto alpha-type alumina (α-Al2O3), which does not bond with bone. The adsorption characteristics of BSA onto AL-P were very different from those onto α-Al2O3 but quite similar to those onto HA. It is speculated that BSA is adsorbed onto AL-P and HA by interionic interactions, while it is adsorbed onto α-Al2O3 by electrostatic attraction. The results suggest that the specific adsorption of albumin onto implant materials might play a role in the expression of the bone-bonding abilities of the materials.

Biohydrogen is considered a promising and environmentally friendly energy source. Escherichia coli BW25113 hyaB hybC hycA fdoG frdc ldhA aceE has been previously engineered for elevated biohydrogen production from glucose. In this study, we show that this strain can also use biomass from oil palm frond (OPF) juice and sewage sludge as substrates. Substrate improvement was accomplished when hydrogen productivity increased 8-fold after enzymatic treatment of the sludge with a mixture of amylase and cellulase. The OPF juice with sewage sludge provided an optimum carbon/nitrogen ratio since the yield of biohydrogen increased to 1.5 from 1.3 mol H2/mol glucose compared to our previous study. In this study, we also reveal that our engineered strain improved 200-fold biohydrogen productivity from biomass sources compared to the unmodified host. In conclusion, we determined that our engineered strain can use biomass as an alternative substrate for enhanced biohydrogen production.

Initial cell responses following implantation are important for inducing osteoconductivity. We investigated cell adhesion, spreading, and proliferation in response to native and bovine serum albumin (BSA)-adsorbed disc of hydroxyapatite (HA) or alpha-type alumina (α-Al2O3) using mouse MC3T3-E1 osteoblastic cells and mouse RAW264.7 macrophages. The adsorbed BSA inhibited adhesion and spreading of MC3T3-E1 cells, but did not affect MC3T3-E1 cell proliferation on HA and α-Al2O3 substrates. Thus, MC3T3-E1 cells quickly adhere to original HA before cell binding is impeded by adsorption of BSA in quantities sufficient to inhibit the adhesion of MC3T3-E1 cells. The adsorbed BSA inhibits adhesion of RAW264.7 cells to α-Al2O3, but not to HA. BSA adsorption does not affect RAW264.7 cell spreading and proliferation on both HA and α-Al2O3 substrates. Thus, BSA adsorbed on HA stimulates a different cell response than α-Al2O3. Moreover, quick adherence of osteoblast cells and monocyte-macrophage lineage cells plays a role in HA osteoconductivity.

Aim This is a non-clinical, proof of concept study, showing that tolvaptan has efficacy in reducing ascites in chronic liver injury, using a rat model induced by repeated dimethylnitrosamine (DMNA) injection. Methods A rat model of chronic liver injury was induced by 10 mg/kg of repeated i.p. injection with DMNA for 6–9 weeks. Tolvaptan was administrated to rats that showed obvious and stable ascites, and abdominal circumference was evaluated as a surrogate marker of ascites volume. Rats were placed in metabolic cages with free access to food and water to collect urine over a 24-h period. Results Oral tolvaptan (1 and 3 mg/kg) promoted a remarkable diuretic effect, decreasing bodyweight and abdominal circumference in a dose-dependent manner. Plasma sodium concentration was increased by tolvaptan due to the large amount of free-water excretion following tolvaptan administration. Conclusion Tolvaptan had therapeutic efficacy in the reduction of ascites in rats with chronic liver injury. These results are consistent with the clinical data showing tolvaptan has therapeutic implications in the reduction of ascites in patients with decompensated cirrhosis.

The glass ionomer cement as one of the dental cements has been subjected to be widespread application in restoring tooth structure. Most of glass ionomer cements employ the poly(acrylic acid) (PAA) as the liquid phase, but the presence of PAA inhibits the apatite formation on the surface in the body environment, which is an essential requirement for exhibiting bone-bonding ability (bioactivity). In this study, poly(γ-glutamic acid) (γ-PGA), a kind of biopolymer, was utilized for cement preparation. The effort of preparation parameters including the glass powders/liquid ratio (P/L) and the concentration ofγ-PGA on diametral tensile strength were investigated. A maximum diametral tensile strength value of11.88±1.43MPa was obtained when the cement sample was prepared by P/L ratio of 1 : 1 and theγ-PGA concentration of 30% after aging for 3 days. The TF-XRD patterns, SEM images, and EDX spectra suggested that the cement induced a precipitation of calcite on the surface after 7 days of immersion in stimulated body fluid (SBF), although the apatite formation was not observed. The present results suggest that the cement has potential to show bioactivityin vivo, because calcite is also reported to be bioactive.

Porous and non-porous titania microspheres with the anatase or rutile phase were successively prepared by the sol–gel process followed by heat treatment at various temperatures. The pore size of the prepared microspheres was effectively controlled by incorporating silica nanoparticles of different diameters. The apatite-forming ability of the microspheres was investigated in a simulated body fluid, with ion concentrations nearly equal to those of human blood plasma. Results indicated that the titania microspheres with either anatase or rutile structure induced the formation of calcium phosphate compounds (CaPs) on the microsphere surface. The deposition of CaPs was more pronounced on the TiO2 microspheres calcined at 600°C (anatase structure) and 800°C (rutile structure), compared to that calcined at 500°C (anatase structure). Additionally, anatase microspheres with smooth surface and low specific surface area favored the formation of CaPs, compared to porous microspheres. This indicates that nanoscale pores do not essentially favor apatite formation.

Several varieties of ceramics, such as Bioglass-type glasses, sintered hydroxyapatite and glass-ceramic A–W, exhibit specific biological affinity, i.e., direct bonding to surrounding bone, when implanted in bony defects. These bone-bonding ceramics are called bioactive ceramics and are utilized as important bone substitutes in the medical field. However, there is a limitation to their clinical applications because of their inappropriate mechanical properties. Natural bone takes a kind of organic–inorganic composite, where apatite nanocrystals are precipitated on collagen fibers. Therefore, problems with the bioactive ceramics can be solved by material design based on the composites. In this paper, current research topics on the development of bioactive organic–inorganic composites inspired by actual bone microstructure have been reviewed in correlation with preparation methods and various properties. Several kinds of inorganic components have been found to exhibit bioactivity in the body environment. Combination of the inorganic components with various organic polymers enables the development of bioactive organic–inorganic composites. In addition, novel biomedical applications of the composites to drug delivery systems, scaffolds for tissue regeneration and injectable biomaterials are available by combining drugs or biological molecules with appropriate control of its microstructure.

Sodium hydroxide (NaOH)-, heat- and autoclave-treated Ti metal did not form apatite in simulated body fluid (SBF) within 604.8ks, although some Na remained on the Ti metal surface after the autoclave treatment. When hot water treatment was applied between NaOH and heat treatments, the Ti metal formed apatite within 604.8ks in SBF. While anatase TiO2 was partially precipitated by the NaOH and heat treatments, it disappeared after subsequent autoclave treatment. By adding hot water treatment between the NaOH and heat treatments, a considerable amount of anatase TiO2 was formed, which remained after the autoclave treatment; the zeta potential of Ti metal was almost zero in SBF. These results indicate that with intermediate hot water treatment, Ti metal can form apatite in SBF even after autoclave treatment. Anatase TiO2, rather than the amount of Na or the zeta potential in SBF, might play an important role in apatite formation.

Phosphate groups on materials surfaces are known to contribute to apatite formation upon exposure of the materials in simulated body fluid and improved affinity of the materials for osteoblast-like cells. Typically, polymers containing phosphate groups are organic matrices consisting of apatite-polymer composites prepared by biomimetic process using simulated body fluid. Ca(2+) incorporation into the polymer accelerates apatite formation in simulated body fluid owing because of increase in the supersaturation degree, with respect to apatite in simulated body fluid, owing to Ca(2+) release from the polymer. However, the effects of phosphate content on the Ca(2+) release and apatite-forming abilities of copolymers in simulated body fluid are rather elusive. In this study, a phosphate-containing copolymer prepared from vinylphosphonic acid, 2-hydroxyethyl methacrylate, and triethylene glycol dimethacrylate was examined. The release of Ca(2+) in Tris-NaCl buffer and simulated body fluid increased as the additive amount of vinylphosphonic acid increased. However, apatite formation was suppressed as the phosphate groups content increased despite the enhanced release of Ca(2+) from the polymer. This phenomenon was reflected by changes in the surface zeta potential. Thus, it was concluded that the apatite-forming ability of vinylphosphonic acid-2-hydroxyethyl methacrylate-triethylene glycol dimethacrylate copolymer treated with CaCl2 solution was governed by surface state rather than Ca(2+) release in simulated body fluid.

One of the most important and novel approaches of biomedical engineering is the development of new, effective and non-invasive medical diagnosis abilities, and treatments that have such requirements as advanced technologies for tumor imaging. Gadolinium (Gd) compounds can be used as MRI contrast agents, however the release of Gd3+ ions presents some adverse side effects such as renal failure, pancreatitis or local necrosis. The main aim of the work was the development and optimization of Gadolinium based nanoparticles coated with silica to be used as bioimaging agent. Gd based nanoparticles were prepared through a precipitation method and afterwards, these nanoparticles were covered with silica, using Stober method with ammonia and functionalized with 3-Aminopropyltriethoxysilane (APTES). Results showed that nanoparticles were homogeneous regarding chemical composition, silica layer thickness, total size and morphology. Also, silica coating was successfully not degraded after 4 weeks at pH 5.5, 6.0 and 7.4, contrary to GdOHCO3 nanoparticles that degraded. Regarding the in vitro cell tests, very good cell proliferation and viability were observed. In conclusion, the results showed that Gd based nanoparticles coated with silica for imaging applications were successfully obtained under a well-controlled method. Furthermore, silica coating may enhance magnetic nanoparticles biosafety because it avoids GdOHCO3 degradation into harmful products (such as Gd3+ ions) at physiological conditions.

Biofilm formation of periodontal pathogens on teeth surfaces promotes the progression of periodontal disease. Hence, understanding the mechanisms of bacterial attachment to the dental surfaces may inform strategies for the maintenance of oral health. Although hydroxyapatite (HA) is a major calcium phosphate component of teeth, effect of biofilm formation on HA surfaces remains poorly characterized. In this study, biofilm-forming abilities by the periodontal pathogens Aggregatibacter actinomycetemcomitans Y4 and Porphyromonas gingivalis 381 were investigated on dense and porous HAs that represent enamel and dentin surfaces, respectively. These experiments showed greater biofilm formation on porous HA, but differing attachment profiles and effects of the two pathogens. Specifically, while the detachment of A. actinomycetemcomitans Y4 biofilm was observed, P. gingivalis 381 biofilm increased with time. Moreover, observations of HA morphology following formation of A. actinomycetemcomitans Y4 biofilm revealed gaps between particles, whereas no significant changes were observed in the presence of P. gingivalis 381. Finally, comparisons of calcium leakage showed only slight differences between bacterial species and HA types and may be masked by bacterial calcium uptake. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2873-2880, 2016.

Initial cellular responses following implantation are important for inducing osteoconduction. We investigated cell adhesion, spreading, proliferation and differentiation of mouse MC3T3-E1 osteoblastic cells on untreated or fibronectin (Fn)-coated discs of hydroxyapatite (HAp) or alpha-type alumina (α-Al2O3). Fn coating significantly enhanced adhesion and spreading of MC3T3-E1 cells on HAp, but did not affect MC3T3-E1 cell proliferation and differentiation on HAp or α-Al2O3. Fn-coated HAp likely does not stimulate pre-osteoblast cells to initiate the process of osteoconduction; however, Fn adsorption might affect the response of inflammatory cells to the implanted material or, in conjunction with other serum proteins, stimulate pre-osteoblast cell proliferation and differentiation. Further studies on the effect of serum proteins in cell culture and the efficacy of Fn-coated HAp and α-Al2O3in vivo are warranted.

Natural bone consists of apatite and collagen fiber. Bioactive materials capable to bonding to bone tissue are clinically used as bone-repairing materials. Apatite-organic polymer composites exhibit bone-bonding abilities and mechanical properties similar to those of natural bone, and these materials can be prepared using biomimetic processes in simulated body fluid (SBF). Specific functional groups such as sulfonic and carboxylic acid groups are known to induce the heterogeneous nucleation of apatite in SBF. However, it remains unclear whether structurally related sulfinic acid groups can contribute to apatite formation in the same way, despite sodium sulfonate being used in biomedical applications as a radical polymerization promoter in adhesive dental resin. Herein, we report the preparation of a new hydrogel containing sulfinic acid groups from sodium 4-vinylbenzenesulfinate and 2-hydroxyethyl methacrylate using a radical polymerization reaction and the subsequent incorporation of Ca

The zeta potential of alumina (Al 2 O 3 ) powder with different crystalline phases, prepared by heat treatment of boehmite, was measured in simulated body fluids in order to discuss the mechanism on in vivo formation of a calcium and phosphorus (CaP)-rich layer on bone cement containing δ-Al 2 O 3 -based bead powder. γ, δ, and θ-Al 2 O 3 powders were obtained by heat treatment of boehmite powder at 600 °C, 900 °C, and 1025 °C, respectively. It was found that δ-Al 2 O 3 gave a negative zeta potential in an acidic simulated body fluid, whereas γ-Al 2 O 3 and θ-Al 2 O 3 gave a positive potentials. During the bone fracture healing process, acidic conditions are maintained at the site of fracture for several days. Consequently, it is speculated that the negative surface potential of δ-Al 2 O 3 in an acidic body fluid, similar to the fracture site, might be responsible for the in vivo formation of the CaP-rich layer on the overlying bone cement, given that the negatively charged surface of δ-Al 2 O 3 would attract calcium ions from the surrounding body fluid, thereby facilitating the formation of the CaP-rich layer.

MC3T3-E1 cell responses, such as cell adhesion and proliferation, to original and bovine serum albumin (BSA) coated disc (original-disc, BSA-disc) of hydroxyapatite (HA) or alpha-type alumina (α-Al2O3) was studied. There was no significant difference in the cell proliferation between BSA-discs and original-discs even after incubated for 14 days, but the cell number at day 14 tended to be higher (p = 0.054) on the BSA-discs of HA than on the original-discs of HA. Incidentally, the amount of adsorbed protein was higher on BSA-discs than on original-discs only until incubated in culture medium for 3 h. BSA adsorption might influence the MC3T3-E1 cell adhesion to HA, as a result the specific adsorption of albumin on HA is likely to affect the expression of the osteoconductivity of materials.

This study is concerning hybrid materials composed of the magnetite and the organic polymer such as dextran. They are useful for hyperthermia of cancer. In the preparation of this material, chemical structure or molecular weight of the added polymer is expected to affect ionic interaction between polymer and iron salts, and consequently the grain size and morphology of the prepared magnetite core. Therefore, we have synthesized magnetite-polymer hybrids using various polymers. Various polymers were dissolved in iron (II) chloride aqueous solution, and then NaOH aqueous solution was added to this mixed solution. As a result, in the case of neutral and cationic polymer crystalline magnetite was precipitated in the hybrid. On the other hand, in the case of anionic polyacrylic acid, lepidocrocite was precipitated rather than magnetite. It is known that the magnetite formation progresses through intermediate Fe (OH)2 formation and oxidation of the Fe (OH)2 by dissolved O2. Therefore it is considered that tight ionic interaction is constructed between the iron ions and the carboxyl group in the polyacrylic acid to form a complex, and the Fe (OH)2 formation is inhibited. When the hybrid was prepared by addition of NaOH aqueous solution to iron (II) chloride solution, and subsequent addition of the different polymers, magnetite formation was not inhibited irrespective of kind of polymer. The present results indicate that crystalline structure of the magnetite phase in magnetite-polymer hybrid is strongly affected by the chemical structure of polymer additives or the order of addition.

Sodium hydroxide (NaOH)-, heat- and autoclave-treated Ti metal did not form apatite in simulated body fluid (SBF) within 7 days although certain amounts of sodium (Na) still remained on the Ti metal surface even after the autoclave treatment. When hot water treatment was applied between NaOH and heat treatment, the Ti metal formed apatite within 7 days in SBF. Anatase-type TiO2 was partially precipitated by the NaOH and heat treatment but it was disappeared by the subsequent autoclave treatment. When the hot water treatment was applied between the NaOH and heat treatment, considerable amount of anatase-type TiO2 was formed and it still remained even after the autoclave treatment. The zeta potential of the Ti metal with the hot water treatment was almost zero in SBF. These results indicate that Ti metal can show apatite-forming ability in SBF even after autoclave treatment, when hot water treatment is applied between the NaOH and heat treatment, and that anatase-type TiO2 might play an important role in the apatite formation rather than the amount of Na and/or the zeta potential.

Chemically synthesized collagen with triple helix structure similar to natural collagen has been developed as a safe biomaterial. If the chemically synthesized collagen is deposited with apatite, they are expected for novel bone substitutes having bioactivity and bioresorbability. Although apatite formation on the chemically synthesized collagen has been examined, highly supersaturated condition such as 1.5SBF with ion concentration 1.5 times those of simulated body fluid (SBF) is needed to achieve apatite formation. In the present study, we intended acceleration on the apatite formation on the chemically synthesized collagen by immobilization with polyglutamic acid (PGA). PGA is known as biodegradable and biocompatible polypeptide having excellent apatite-forming ability. We examined effects of the immobilization procedure on mineralization behavior in SBF. At first, PGA was immobilized on porous sponges of chemically synthesized collagen in aqueous solutions containing PGA and CaCl2. As a result, not only apatite but also calcite-type CaCO3 was deposited on the specimens in SBF. The calcite formation was occurred during the treatment with PGA solution. pH of the solution was adjusted to 7 by NaOH solution in order to avoid dissolution of the collagen. During this procedure, Ca (OH)2 would be precipitated by locally increase in pH of the solution and converted into the calcite. When the PGA solution treatment was shortened so as to prevent the calcite formation, single phase of the apatite was formed in SBF. The present results indicate that crystalline phase deposited on the chemically synthesized collagen can be controlled by fabrication procedure, and provide fundamental design of composites containing apatite and chemically synthesized collagen useful for bone regeneration.

Hyperthermia is a minimally invasive cancer treatment. As hyperthermia thermoseeds, ferromagnetic microcapsules of 20–30 μm in diameter have attracted much attention since their embolization effect cuts off the nutrition supply into cancer cells, ensuring that the microcapsules efficiently reach the tumor. In the present study, ferromagnetic microcapsules were prepared via iron hydroxide precipitation from a water/oil emulsion and subsequent hydrothermal treatment. The fundamental conditions for obtaining microcapsules of suitable size were investigated. The diameter of the obtained microcapsules tended to decrease as rotation speed increased during emulsion preparation or surfactant concentration in the oil phase. The sphericity of the microcapsules was improved at low surfactant concentration. A large amount of 20–30 μm-diameter magnetite microcapsules were obtained when the rotation speed and surfactant concentration were fixed at 1500 rpm and 0.35 mass%, respectively. The obtained microcapsules embedded in agar phantom exhibited heat generation under an alternating magnetic field.