What's New
2018（July－December）
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2018.12.29
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2018.12.27
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2018.12.26
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2018.12.19
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2018.12.1
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2018.11.27
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2018.11.19
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2018.11.12
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2018.11.5
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2018.10.27
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2018.10.26
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2018.10.16
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2018.10.12
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2018.10.9
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2018.10.3
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2018.9.19
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2018.9.19
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2018.9.15
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2018.8.27
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2018.7.29
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2018.7.22
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2018.7.6
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2018.12.29
A paper showing that "autogenous bone grafting is not always the cause of good bone union" was published in Materials Transactions as an open access journal.
Hiroyuki Takahashi, Takuya Ishimoto, Takayuki Inoue, Hiroomi Kimura, Keita Uetsuki, Natsuki Okuda, Yohei Nakanishi, Jong Yeong Oh, Manabu Ito, Yoshio Nakashima, Takao Hanawa, Takayoshi Nakano*:
Effects of Autogenous Bone Graft on Mass and Quality of Trabecular Bone in Ti–6Al–4V Spinal Cage Fabricated with Electron Beam Melting,
Materials Transactions, 60 [1], (2019), pp.144-148.
DOI:.org/10.2320/matertrans.M2018329.Abstract
A spinal cage is one of the primary spinal devices used for the treatment of spinal diseases such as lumbar spondylolisthesis. Since it is set in the intervertebral space that causes instability to promote the fusion of the adjacent vertebral bodies, it requires the early induction of healthy bones. For this reason, in most cases, an autogenous bone extracted from the patient’s ilium is implanted in the interior of the cage to stimulate bone formation. However, collecting autogenous bone involves secondary surgery and several clinical problems such as pain in the part from which it is collected. Additionally, the effect of the autogenous bone graft itself has not been sufficiently studied yet. Moreover, the mechanical functions of trabecular bones in a vertebral body are governed by the anisotropic structure of the trabeculae and the preferential orientation of the apatite/collagen in a trabecula with respect to the principal stress. Despite this fact, after the implantation of the cage, the mass of the bones is evaluated with soft X-ray photography, which does not guarantee an accurate measurement of bone functions. In this study, the effect of the autogenous bone graft on the spinal cage was verified based on structural anisotropy of trabecular bones and the preferential orientation of apatite/collagen in a trabecula using sheep. The autogenous bone graft demonstrated a significant effect on the increase of bone mass and anisotropy of the trabecular structure. However, compared to the trabecular anisotropy of normal parts, the anisotropy of the trabecular structure and apatite c-axis orientation of the parts with autogenous bone graft were considerably lower, indicating a minimal effect of the autogenous bone graft. Therefore, it was suggested that early stabilization of the spinal cage requires another strategy that rapidly forms the unique hierarchical anisotropic structure of trabecular bones.
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2018.12.27
A paper demonstrating that osteoporosis significantly alters bone orientation from its optimal value was published in Calcified Tissue International as an open access journal. This is a collaborative research with Department of Orthopaedic Surgery, Osaka
Ryosuke Ozasa, Takuya Ishimoto, Sayaka Miyabe, Jun Hashimoto, Makoto Hirao, Hideki Yoshikawa, Takayoshi Nakano*:
Osteoporosis changes collagen/apatite orientation and Young’s modulus in vertebral cortical bone of rat,
Calcified Tissue International, (2018), pp.449-460.
DOI:10.1007/s00223-018-0508-zAbstract
This study revealed the distinguished changes of preferential orientation of collagen and apatite and Young’s modulus in two different types of osteoporotic bones compared with the normal bone. Little is known about the bone material properties of osteoporotic bones; therefore, we aimed to assess material properties in osteoporotic bones. 66 female Sprague–Dawley rats were used. We analyzed the volumetric bone mineral density, collagen/apatite orientation, and Young’s modulus of fifth lumbar vertebral cortex for osteoporotic rats caused by ovariectomy (OVX), administration of low calcium and phosphate content (LCaP) diet, and their combination (OVX+LCaP), as well as sham-operated control. Osteocyte conditions were assessed by hematoxylin and eosin and immunohistochemical (matrix extracellular phosphoglycoprotein (MEPE) and dentin matrix protein 1 (DMP1)) staining. All osteoporotic animals showed bone loss compared with the sham-operated control. OVX improved craniocaudal Young’s modulus by enhancing collagen/apatite orientation along the craniocaudal axis, likely in response to the elevated stress due to osteoporotic bone loss. Conversely, LCaP-fed animals showed either significant bone loss or degraded collagen/apatite orientation and Young’s modulus. Osteocytes in LCaP and OVX+LCaP groups showed atypical appearance and MEPE- and DMP1-negative phenotype, whereas those in the OVX group showed similarity with osteocytes in the control group. This suggests that osteocytes are possibly involved in the osteoporotic changes in collagen/ apatite orientation and Young’s modulus. This study is the first to demonstrate that osteoporosis changes collagen/apatite orientation and Young’s modulus in an opposite manner depending on the cause of osteoporosis in spite of common bone loss. -
2018.12.26
Three collaborative papers from Nakano Lab have been published in Materials Science Forum.
Mitsuharu Todai, Takeshi Nagase, Takao Hori, Hiroyuki Motoki, Shi-Hai Sun, Koji Hagihara, Takayoshi Nakano:
Fabrication of the Beta-Titanium Alloy Rods from a Mixture of Pure Metallic Element Powders via Selected Laser Melting,
Materials Science Forum, 941, (2018), pp.1260-1263.
doi:10.4028/www.scientific.net/MSF.941.1260Abstract
The powder-bed additive manufacturing (AM) process offers advantages in terms of reduced material waste, ability to create complex shape and a decrease in the lead time from design to manufacturing. Recently, custom-made implant of Ti alloys is being developed by selective laser melting (SLM) in additive manufacturing (AM) process. However, the difficulty in the fabrication of titanium alloys due to their pre-alloyed powder cost, resulting in a limited usage of titanium alloys. To overcome this disadvantage, it is effective to fabricate the Ti alloys by SLM from mixture of pure elemental powders. In this case, it is avoided the preparing of the pre-alloyed powders. Therefore, the purpose of the present study is the trying to the fabrication of the Ti-20at.%X (X = Cr, Nb) alloys from the mixture of pure elemental powders by SLM.Click here for this PDF.
Masahiro Sakata, Jong Yeong Oh, Ken Cho, Hiroyuki Y. Yasuda, Mitsuharu Todai, Takayoshi Nakano, Ayako Ikeda, Minoru Ueda, Masao Takeyama:
Effects of Heat Treatment on Unique Layered Microstructure and Tensile Properties of Tial Fabricated by Electron Beam Melting,
Materials Science Forum, 941, (2018), pp. 1366-1371.
doi:10.4028/www.scientific.net/MSF.941.1366Abstract
In the present study, effects of heat treatment on microstructures and tensile properties of the cylindrical bars of Ti-48Al-2Cr-2Nb (at.%) alloy with unique layered microstructure consisting of equiaxed γ grains region (γ band) and duplex-like region fabricated by electron beam melting (EBM) were investigated. We found that it is possible to control width of the γ bands (Wγ) by heat treatments at 1100°C and 1190°C. The Wγ increases with decreasing heat treatment temperature. The bars heat-treated at 1190°C exhibit high elongation of 2.9% at room temperature (RT) with maintaining high strength. The RT elongation increases with increasing the Wγ because of increasing deformable regions. In contrast, the RT elongation of the bars decreases with increasing the Wγ when Wγ is very large. This is because the large γ band leads intergranular fracture. These results indicate that there is appropriate width for the γ band to obtain excellent tensile properties at RT.Click here for this PDF.
Ken Cho, Ryota Kobayashi, Takuma Fukuoka, Jong Yeong Oh, Hiroyuki Y. Yasuda, Mitsuharu Todai, Takayoshi Nakano, Ayako Ikeda, Minoru Ueda, Masao Takeyama:
Microstructure and Fatigue Properties of TiAl with Unique Layered Microstructure Fabricated by Electron Beam Melting,
Materials Science Forum, 941, (2018), pp. 1597-1602.
doi:10.4028/www.scientific.net/MSF.941.1597Abstract
In Ti-48Al-2Cr-2Nb (at.%) alloys fabricated by electron beam melting (EBM), a unique layered microstructure composed of duplex-like region and equiaxed γ grains (γ bands) is formed at an appropriate process condition. The fatigue behavior of the TiAl alloy fabricated by EBM at an angle ( θ ) of 90° between the building direction and loading axis was investigated focusing on the layered microstructure and test temperature. At room temperature (RT), fatigue strength at θ = 90° is higher than that at θ = 0°. In particular, in low-cycle fatigue life region, the fatigue properties at θ = 90° without hot isostatic pressing (HIP) are comparable to those of the cast alloys with HIP. The γ bands act as an effective barrier to the crack propagation, resulting in high fatigue strength at RT. On the other hand, the fatigue strength at θ = 90° is lower than that at θ = 0° in low-cycle fatigue life region at 1023 K, since the γ bands cannot suppress the crack propagation at 1023 K. However, at 1023 K, the fatigue strength at θ = 90° in the low-cycle region is similar to that of the cast alloys with HIP, due to the fine grain size after EBMClick here for this PDF.
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2018.12.19
Our research on the development of a new anisotropic low elasticity βTi alloy and its guidelines was published in "JALCOM" as an open access journal.
Pan Wang*, Mitsuharu Todai, Takayoshi Nakano*:
Beta titanium single crystal with bone-like elastic modulus and large crystallographic elastic anisotropy,
Journal of Alloys and Compounds, (2018),pp.1-17
DOI: 10.1016/j.jallcom.2018.12.236.Abstract
To develop single crystalline beta titanium implant as new hard tissue replacements for suppressing the stress shielding, we design a Ti-26.6Nb-6.7Al alloy (at. %) single crystal that exhibits large crystallographic elastic anisotropy and low Young's modulus. The anisotropy factor, A, reaches 3.42 that is the highest among all the reported values. The Young's modulus along 〈<100〉> direction, E100, is only 36 GPa that is similar to the Young's modulus of cortical bone. These results prove our proposed design strategy and provide a new path to design beta titanium single crystal with bone-like elastic modulus for implant to minimize stress shielding.
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2018.12.1
Two commentary articles ("Microstructure Research Frontiers for Materials Development by Microscopy (11)" - Development of Microscopy for Materials Evaluation and Progress of Advanced Evaluation Methods) were published in Matelia.
Ryosuke Ozasa, Takayoshi Nakano:
Visualization of Vascular Network in Bone Marrow by In vivo Imaging, Special Issue on Microstructure Research Frontiers for Materials Development by Microscopy (11) - Development of Microscopy for Materials Evaluation and Advanced Evaluation Methods-,
Materia, 57 [12], (2018), pp. 598.Click here for this PDF.
Koji Hagiwara, Takayoshi Nakano, Michiaki Yamazaki, Yoshihito Kawamura:
Peculiar deformation zone formation in various anisotropic materials including Mg-based LPSO phase, Special Issue on "Frontiers of Microstructure Research for Materials Development by Microscopy (11)" - Development of Microscopy for Materials Evaluation and Progress of Advanced Evaluation Methods-,
Materia, 57 [12], (2018), pp. 607.Click here for this PDF.
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2018.11.27
Ms. Wu (M2) won the Technical Encouragement Award at the Autumn Meeting of Smart Processing Society for Materials, Environment & Energy.
Siki Wu, Takuya Ishimoto, Shihai Sun, and Takayoshi Nakano: fabrication and microstructure of
Fabrication and microstructure of stainless steel components by laser additive manufacturing,
the Autumn Meeting of Smart Processing Society for Materials, Environment & Energy, Nihonbashi Life Science Building, November 27, 2018. -
2018.11.19
Our paper on AM of βTi alloy has been published in the journal of Smart Processing Society for Materials, Environment & Energy.
Takuya Ishimoto, Jumpei Yasutomi, Shota Sugimoto, and Takayoshi Nakano:
Assembly microstructure formation in β-type Ti-15Mo-5Zr-3Al alloy by laser additive manufacturing,
Journal of Smart Processing Society for Materials, Environment & Energy, 7 [6],(2018),pp.229-232.Abstract
Selective laser melting (SLM), a kind of additive manufacturing (AM) technologies, enables to fabricate highly complicated 3-dimensional structures from a powdered metallic materials. Recent investigations demonstrated the ability of SLM to form crystallographically texturized parts. Highly texturized materials exhibit anisotropic functions; therefore, control of texture via AM is becoming attractive strategy for developing functionalized materials. In the present study, we tried to find laser conditions for formation of randomly and highly texturized parts in SLM of T-15Mo-5Zr-3Al biomedical alloy. We successfully achieved randomly and highly texturized parts under the conditions of (low laser power and low scan speed) and (high laser power and high scan speed), respectively. The highly texturized part showed anisotropy in Young’s modulus in which the value in <001> oriented direction was significantly lower than that in <011> oriented direction, the similar trend to those reported in single crystal of this alloy. The evolution of crystallographic texture was thought to be related with melt-pool shape, which needs further investigations.
Click here for this PDF.
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2018.11.12
Dr. Ishimoto received the Scientific Encouragement Award at the 40th Annual Meeting of the Japanese Society for Biomaterials, and gave the award lecture.
Takuya Ishimoto:
Quantitative analysis of bone collagen/apatite crystal orientation and elucidation of bone regeneration mechanism,
Scientific Encouragement Award of the Japanese Society for Biomaterials, The 40th Annual Meeting of the Japanese Society for Biomaterials (Kobe International Conference Center), November 12, 2018.～Comments from Dr. Ishimoto
I am very happy to receive such a prestigious award. I would like to express my sincere gratitude to Dr. Nakano, the students of Nakano Lab, and the many professors with whom I have collaborated for their guidance and cooperation. Thank you very much. I will continue to work hard on biomaterials and bone research for biomaterials, and I look forward to your guidance. -
2018.11.5
A paper on the mechanism of bone metastasis of cancer has been published in Int. J. Mol. Sci (MDPI).
A. Matsugaki, T. Harada, Y. Kimura, A. Sekita, T. Nakano:
Dynamic Collision Behavior Between Osteoblasts and Tumor Cells Regulates the Disordered Arrangement of Collagen Fiber/Apatite Crystals in Metastasized Bone,
Int. J. Mol. Sci., 19(11), (2018), 3474.pages.1-11
https://doi.org/10.3390/ijms19113474Abstract
Bone metastasis is one of the most intractable bone diseases; it is accompanied with a severe mechanical dysfunction of bone tissue. We recently discovered that the disorganized collagen/apatite microstructure in cancer-bearing bone is a dominant determinant of the disruption of bone mechanical function; disordered osteoblast arrangement was found to be one of the principal determinants of the deteriorated collagen/apatite microstructure. However, the precise molecular mechanisms regulating the disordered osteoblast arrangement triggered by cancer invasion are not yet understood. Herein, we demonstrate a significant disorganization of bone tissue anisotropy in metastasized bone in our novel ex vivo metastasis model. Further, we propose a novel mechanism underlying the disorganization of a metastasized bone matrix: A dynamic collision behavior between tumor cells and osteoblasts disturbs the osteoblast arrangement along the collagen substrate.
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2018.10.27
Mr. Ozasa (D3) and Mr. Okuda (M1) won the Most Best Poster Award, and Mr. Kobayashi (M1), Mr. Sasaki, Mr. Harada, and Mr. Moriguchi (M1) won the Best Poster Award at the 1st Japan Institute of Metals and Materials 4th Field Conference.
The Most Best Poster Award
〇Ryosuke Ozasa, Takuya Ishimoto, Sayaka Miyabe, Jun Hashimoto, Hideki Yoshikawa, and Takayoshi Nakano:
Collagen/apatite orientation changes in vertebrae of osteoporotic rats.〇Natsuki Okuda, Takuya Ishimoto, Masami Tanaka, Minoru Watanabe, Hitoshi Amano, and Takayoshi Nakano:
Elucidation of the relationship between endochondral ossification and bone matrix orientationBest Poster Award
〇Yoshiya Kobayashi, Takuya Ishimoto, Hiroyuki Takahashi, Takayuki Inoue, Mitsuomi Kimura, Keita Uetsuki, Yoshio Nakajima, Manabu Ito, Takao Hanawa, and Takayoshi Nakano:
Novel vertebral body device design for induction of oriented bone matrix〇Kyohei Sasaki, Ryosuke Kozasa, and Takayoshi Nakano:
Contribution of Apolipoprotein E to the Regulation of Bone Orientation〇Tatsuki Harada, Aira Matsugaki, Takayoshi Nakano:
Regulatory behavior of osteoblast arrays based on intercellular signals with cancer cells.〇Atsushi Moriguchi, Ryosuke Ozasa, Aira Matsugaki, Takayoshi Nakano:
Involvement of osteoclast-derived factors in bone tissue orientation -
2018.10.26
Our collaborative research with Hagiwara Lab on strengthening of Mg alloys has been published in Acta Materialia as an open access journal.
Koji Hagihara, Zixuan Lia, Michiaki Yamasaki, Yoshihito Kawamura, Takayoshi Nakano:
Strengthening mechanisms acting in extruded Mg-based long-period stacking ordered (LPSO)-phase alloys,
Acta Materialia: volume163, pages 226-239.
https://doi.org/10.1016/j.actamat.2018.10.016Abstract
The unusual increase in the strength by extrusion is a unique feature of recently developed Mg alloys containing the LPSO phase. In this study, we first elucidated the detailed mechanisms that induce this drastic strengthening. The dependencies of the deformation behavior of a Mg88Zn4Y7 extruded alloy, which contains ∼86-vol% LPSO phase, on the temperature, loading orientation, and extrusion ratio were examined. It was found that the yield stress of the alloy is drastically increased by extrusion, but the magnitude of the increase in the yield stress is significantly different depending on the loading orientation. That is, the strengthening of the LPSO phase by extrusion shows a strong anisotropy. By the detailed analyses, this was clarified to be derived from the variation in the deformation mechanisms depending on the loading orientation and extrusion ratio. Basal slip was found to govern the deformation behavior when the loading axis was inclined at a 45° to the extrusion direction, while the predominant deformation mechanism varies from basal slip to the formation of deformation kink bands as the extrusion ratio increased when the loading axis was parallel to the extrusion direction. Moreover, it was clarified in this study that the introduction of a deformation-kink-band boundary during extrusion effectively acts as a strong obstacle to basal slip. That is, "the kink band strengthening" was first quantitatively elucidated, which contributes to the drastic increase in the yield stress of the extruded LPSO-phase alloys in the wide temperature range below 400 °C.
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2018.10.16
Our paper on bio-apatite crystal orientation in human edentulous mandibular anterior cortical bone with Tokyo Dental College has been published in JBMR-B.
Takehiro Furukawa,Satoru Matsunaga,Toshiyuki Morioka, Takayoshi Nakano, Shinichi Abe, Masao Yoshinari, Yasutomo Yajima:
Study on bone quality in the human mandible—Alignment of biological apatite crystallites,
Journal of Biomedical Materials Research Part B, 107B (2018) ,pp.838–846.
DOI: 10.1002/jbmb.34180Abstract
The importance of considering bone quality during oral implant treatment is increasingly being recognized. Assessment of bone quality in response to changes in the jaw bone is extremely important when planning treatment. The present study analyzed biological apatite (BAp) crystallites, a bone quality factor, in order to investigate crystallographic anisotropy in dentate and edentulous human mandibles. Using mandibular samples from Japanese adult cadavers, a region of interest was established comprising cortical bone in the central incisors. Samples were classified into five morphological categories based on the extent of bone resorption. Bone mineral density (BMD) was measured and diffraction intensity ratios were calculated using a microbeam X‐ray diffraction system. While no differences were observed in BMD, differences were observed in BAp crystallite alignment between the measurement points. In the alveolar region, samples with residual alveolar bone showed strong alignment in the occlusal direction, while samples with marked alveolar bone resorption had preferential alignment in the mesiodistal direction. The present findings suggest that tooth loss and the extent of alveolar bone resorption affects bone quality in the mandible. © 2018 Wiley Periodicals, Inc. J. Biomed. Mater. Res. Part B: 2018.
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2018.10.12
Our research on the improvement of strength and ductility of Co-Cr-Mo alloys by special low-temperature heat treatment, in collaboration with Narushima Lab. of Tohoku University, has been published in Materials Science and Engineering A as an open access
Kosuke Ueki*, Mai Abe, Kyosuke Ueda, Masaaki Nakai, Takayoshi Nakano and Takayuki Narushima:
Synchronous improvement in strength and ductility of biomedical Co–Cr–Mo alloys by unique low-temperature heat treatment,
Materials Science and Engineering: A Volume 739, pages 53-61.
https://doi.org/10.1016/j.msea.2018.10.016Abstract
The microstructure and tensile properties of Co–27Cr–6Mo (mass%) alloys heat-treated at 673–1373 K were studied. Lower elongation was observed after heat treatment at 1073 K due to formation of carbonitride precipitates. In contrast, when low-temperature heat treatment (LTHT) was applied at 673–873 K, both the ultimate tensile strength and elongation synchronously improved compared with the solution-treated alloy.Electron backcatter diffraction analysis for plastic-strained alloys and in situ X-ray diffraction analysis under stress-induced conditions revealed that the strain-induced martensitic transformation (SIMT) of the γ(fcc)-phase to ε(hcp)-phase during plastic deformation was suppressed by the LTHT. Stacking faults (thin ε-phase) were observed to collide in the LTHT alloys. The following mechanisms for the synchronous improvement in the tensile strength and elongation after LHTH are proposed. First, stacking faults with multiple variants were formed during LTHT. Then, the ε-phase of a single variant formed by SIMT during plastic deformation collides with preexisting multi-variant stacking faults formed during LTHT, increasing the tensile strength. In addition, the SIMT during plastic deformation is suppressed in the high-plastic-strain region by the collision. This decreases the total amount of ε-phase formed during plastic deformation, which improves the ductility. We demonstrated that LTHT of Co–Cr–Mo alloys effectively improves the performance and mechanical safety of spinal fixation implants, which often fracture because of fatigue cracking.
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2018.10.9
A paper on the design of a novel vertebral cage has been published in the journal Clinical Biomechanics.
Hiroyuki Takahashi, Takuya Ishimoto, Yoshiya Kobayashi, Manabu Ito, Takayuki Inoue，Yoshio Nakashima, Takayoshi Nakano:
Design and development of spinal cage for rapid induction of new bone with preferential collagen/apatite orientation,
the journal Clinical Biomechanics, Vol.39 (2018), pp.199-206. -
2018.10.3
Nakano Lab's article has been published in the October issue of "Applied Physics" (2018).
Takayoshi Nakano, Takuya Ishimoto:
Elucidation of the Oriented Structure of Bone Matrix from a Materials Perspective and Development of Bone Substitute Materials to Promote Bone Orientation,
Applied Physics, October, (2018).Click here for this paper.
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2018.9.19
At the 163rd Annual Meeting of the Japan Institute of Metals, Dr. Nakano received the 16th Japan Institute of Metals and Materials Distinguished Achievement Award (Academic Division), Dr. Aiko Sekita, Dr. Aira Matsugaki, and Dr. Takayoshi Nakano received
At the 163rd Annual Meeting of the Japan Institute of Metals, Dr. Nakano received the 16th Japan Institute of Metals and Materials Distinguished Achievement Award (Academic Division), Dr. Aiko Sekita, Dr. Aira Matsugaki, and Dr. Takayoshi Nakano received the 66th Japan Institute of Metals and Materials The Best Paper Award(Microstructure Division), Dr. Naoko Ikeo (currently Assistant Professor at Kobe University) received the 28th Japan Institute of Metals and Materials Young Researcher Award, and Mr. Yasutomi (M2) received the 31st Japan Institute of Metals and Materials The Metals Best Poster Award.
〇Takayoshi Nakano：
the 16th Japan Institute of Metals and Materials Distinguished Achievement Award (Academic Division), the 163rd Annual Meeting of the Japan Institute of Metals, 2018/9/19.〇Aiko Sekita, Aira Matsugaki and Takayoshi Nakano:
Structural crosstalk between crystallographic anisotropy in bone tissue and vascular network analyzed with a novel visualization method,（Materials Transactions, 58 [2], (2017), pp. 266-270.),
the 66th Japan Institute of Metals and Materials The Best Paper Award(Microstructure Division), the 163rd Annual Meeting of the Japan Institute of Metals, 2018/9/19.〇Naoko Ikeo：
28th Japan Institute of Metals and Materials Young Researcher Award, the 163rd Annual Meeting of the Japan Institute of Metals, 2018/9/19.〇Jumpei Yasutomi:
the 31st Japan Institute of Metals and Materials The Metals Best Poster Award, the 163rd Annual Meeting of the Japan Institute of Metals, 2018/9/19. -
2018.9.19
Our paper on laser additive manufacturing of SUS316L steel has been published in "Scripta Materialia" as an open access journal.
Shi-Hai Sun, Takuya Ishimoto#, Koji Hagihara, Yusuke Tsutsumi, Takao Hanawa, Takayoshi Nakano*:
Excellent mechanical and corrosion properties of austenitic stainless steel with a unique crystallographic lamellar microstructure via selective laser melting,
Scripta Materialia, 159 (2018), pp.89-93. These authors(#) contributed equally to this work.Abstract
We first developed a unique “crystallographic lamellar microstructure” (CLM), in which two differently oriented grains appear alternately, in a 316L stainless steel specimen via selective laser melting technology. The CLM was composed of major 〈011〉 grains and minor 〈001〉 grains aligned along the build direction, which stemmed from vertical and approximately ±45° inclined columnar cells formed in the central and side parts of melt-pools, respectively. The development of CLM was found to largely improve the material properties via the strengthening of the product, simultaneously showing superior corrosion resistance to commercially obtained specimens.
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2018.9.15
Our paper on biomimetic calcification, which is a collaborative research with Okayama University, has been published in Journal of Materials Chemistry B as an open access journal.
Emilio Hara, Masahiro Okada, Takuo Kuboki, Takayoshi Nakano, Takuya Matsumoto*:
Rapid bioinspired mineralization using cell membrane nanofragments and alkaline milieu,
Journal of Materials Chemistry B, (2018),
DOI: 10.1039/c8tb01544aAbstract
Bone is a sophisticated organic–inorganic hybrid material, whose formation involves a complex spatiotemporal
sequence of events regulated by the cells. A deeper understanding of the mechanisms behind
bone mineralization at different size scales, and using a multidisciplinary approach, may uncover novel
pathways for the design and fabrication of functional bone tissue in vitro. The objectives of this study
were first to investigate the environmental factors that prime initial mineralization using the secondary
ossification center as an in vivo model, and then to apply the obtained knowledge for rapid in vitro
synthesis of bone-like tissue. First, the direct and robust measurement of pH showed that femur
epiphysis is alkaline (pH D 8.5) at the initial mineral stage at post-natal day 6. We showed that the
alkaline milieu is decisive not only for alkaline phosphatase activity, which precedes mineral formation at
P6, but also for determining initial mineral precipitation and spherical morphology. Next, engineering
approaches were used to synthesize bone-like tissue based on alkaline milieu and artificial chondrocyte
membrane nanofragments, previously shown to be the nucleation site for mineral formation.
Interestingly, mineralization using artificial cell membrane nanofragments was achieved in just 1 day.
Finally, ex vivo culture of femur epiphysis in alkaline pH strongly induced chondrocyte burst, which was
previously shown to be the origin of chondrocyte membrane nanofragments, and also enhanced
mineral formation. Taken together, these findings not only shed more light on the microenvironmental
conditions that prime initial bone formation in vivo, but they also show that alkaline milieu can be used
as an important factor for enhancing methods for in vitro synthesis of bone tissue. -
2018.8.27
The results of the collaborative research between Hagiwara Lab. and Nakano Lab. were introduced in the magazine "Choice" as "Research on 'Superalloys' that contribute to improving thermal efficiency.
Click here for this PDF.
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2018.7.29
The results of our collaboration with a group in India on DDS of two types of growth factors were published online in Acta Biomaterialia.
Manitha Nair*, Shruthy Kuttappan, Dennis Mathew, Jun-ichiro Jo, Ryusuke Tanaka, Deepthy Menon, Takuya Ishimoto, Takayoshi Nakano, Shantikumar V Nair, Yasuhiko Tabata:
Dual release of growth factor from a nanocomposite fibrous scaffold promotes vascularisation and bone regeneration in a rat critical sized calvarial defect,
Acta Biomater., anailable online 29 Jul , Vol 78(2018), pp.36-47.
doi: 10.1016/j.actbio.2018.07.050. [Epub ahead of print]Abstract
A promising strategy for augmenting bone formation involves the delivery of multiple osteoinductive and vasculogenic growth factors locally. However, success depends on sustained growth factors release and its appropriate combination to induce stem cells and osteogenic cells at the bony site. Herein, we have developed a nanocomposite fibrous scaffold loaded with fibroblast growth factor 2 (FGF2) and bone morphogenetic protein 2 (BMP2) and its ability to promote vascularisation and bone regeneration in critical sized calvarial defect was compared to the scaffold with vascular endothelial growth factor (VEGF) + BMP2. Simple loading of growth factors on the scaffold could provide a differential release pattern, both in vitro and in vivo (VEGF release for 1 week where as BMP2 and FGF2 release for 3 weeks). Among all the groups, dual growth factor loaded scaffold (VEGF+BMP2 & FGF2+BMP2) enhanced vascularisation and new bone formation, but there was no difference between FGF2 and VEGF loaded scaffolds although its release pattern was different. FGF2 mainly promoted cell migration, whereas VEGF augmented new blood vessel formation at the defect site. This study suggests that biomimetic nanocomposite scaffold is a promising growth factor delivery vehicle to improve bone regeneration in critical sized bone defects.Statement of Significance
Many studies have shown the effect of growth factors like VEGF-BMP2 or FGF2-BMP2 in enhancing bone formation in critical sized defects, but there are no reports that demonstrate the direct comparison of VEGF-BMP2 and FGF2-BMP2. In this study, we have developed a nanocomposite fibrous scaffold that could differentially release growth factors like VEGF, BMP2 and FGF2 (VEGF release for 1 week where as BMP2 and FGF2 release for 3 weeks), which in turn promoted neovascularisation and new bone formation in critical size defect. There was no difference in vascularisation and bone formation induced by VEGF+BMP2 or FGF2+BMP2. The growth factor was loaded in a simple manner, which would ensure ease of use for the end-user, especially for the surgeon treating a patient in an operating room.Click here for this paper.
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2018.7.22
Our collaborative research with the Department of Conservative Medicine, Graduate School of Dentistry, Osaka University was published in the journal Clinical Oral Investigations.
Motoki Okamoto, Yusuke Takahashi, Shungo Komichi, Manahil Ali, Naomichi Yoneda, Takuya Ishimoto, Takayoshi Nakano, Mikako Hayashi:
Novel evaluation method of dentin repair by direct pulp capping using high-resolution micro-computed tomography,
Clinical Oral Investigations, (2018) pp.1-9Abstract
Objectives
We evaluated a novel micro-computed tomography (micro-CT) assessment for quality and quantity of dentin repair, which is difficult to visualize by histological analysis, after direct pulp capping under standardized cavity preparation.Materials and methods
Standardized cavities were prepared on Wistar rats and direct pulp capping was performed using two commercial bioceramics, ProRoot MTA, and iRoot BP Plus. After 2 or 4 weeks, quality and quantity of tertiary dentin formation were evaluated using high-resolution micro-CT analyses including dentin mineral density, dentin mineral contents, compactness and integrity of tertiary dentin, and dentin volume with/without void space. Reproducibility of micro-CT analyses was confirmed by histological evaluation of the same specimen.Results
The exposed pulp area sizes were similar between iRoot BP Plus and ProRoot MTA. Micro-CT analysis of 2-week samples showing compactness of tertiary dentin was significantly higher in iRoot BP Plus than ProRoot MTA (p < 0.05). Tertiary dentin volume without void space, dentin mineral contents, and density were not significantly different between the groups. In 4-week samples, a significant increase was observed in dentin mineral density, compactness, and dentin volume with/without void space induced by iRoot BP Plus (p < 0.05). Micro-CT analysis of tertiary dentin integrity demonstrated that some ProRoot MTA specimens had small defects and lacked continuity (6/512 images). No defects were observed with iRoot BP Plus.Conclusions
Micro-CT analysis was confirmed as an accurate, objective, and inclusive approach for evaluating quality and quantity of dentin repair.Clinical relevance
These multifaceted approaches to evaluate pulp capping materials may accelerate review processes, ultimately improving vital pulp therapy.Keywords
Micro-computed tomography evaluation Direct pulp capping iRoot BP Plus Mineral trioxide aggregateClick here for this paper.
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2018.7.6
Our paper with Dr. Pan Wang, who is active in Singapore, has been published in "JALCOM" as an open access journal.
Pan Wang*, Mitsuharu Todai, Takayoshi Nakano*;
ω-phase transformation and lattice modulation in biomedicalβ-phase Ti-Nb-Al alloys,
Journal of Alloys and Compounds,766, (2018) pp.511-516.Abstract
Athermal ω-phase transformation and the appearance of the lattice modulation in Ti-28Nb-xAl alloys were investigated by electrical resistivity measurements and transmission electron microscopy (TEM) observations. As a result, the athermal ω-phase is gradually suppressed with increasing Al content. In addition, the lattice modulation is also observed in Ti-28Nb-xAl alloys (0 ≤ x ≤ 7, in at.%) because of the transverse wave with a propagation vector of q = 1/2[ζζ¯0]∗ and displacement in [110]. These results imply that the ω-phase can be controlled by addition of the Al content in Ti-Nb alloys, leading to the development of low Young's modulus β-phase Ti biomedical alloys single crystal.