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Template-assisted freeze casting of macroporous Ti6Al4V scaffolds with long-range order lamellar structure
Journal Pre-proofs Template-assisted freeze casting of macroporous Ti6Al4V scaffolds with longrange order lamellar structure Zhuyin Chen, Xinli Liu, Ting Shen, Chuanzong Wu, Lei Zhang PII: DOI: Reference:
S0167-577X(20)30079-3 https://doi.org/10.1016/j.matlet.2020.127374 MLBLUE 127374
To appear in:
Materials Letters
Received Date: Revised Date: Accepted Date:
28 July 2019 6 January 2020 17 January 2020
Please cite this article as: Z. Chen, X. Liu, T. Shen, C. Wu, L. Zhang, Template-assisted freeze casting of macroporous Ti6Al4V scaffolds with long-range order lamellar structure, Materials Letters (2020), doi: https:// doi.org/10.1016/j.matlet.2020.127374
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
© 2020 Published by Elsevier B.V.
Template-assisted freeze casting of macroporous Ti6Al4V scaffolds with long-range order lamellar structure Zhuyin Chen a, Xinli Liu b, Ting Shen a, Chuanzong Wu a, Lei Zhang a, a
State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083, PR China b
School of Materials Science and Engineering, Central South University, Changsha, Hunan, 410083, PR China
Abstract ： A modified water-based freeze casting to fabricate long-range order lamellar Ti6Al4V scaffolds with macropores and high porosity has been developed by using the pre-frozen WS2 substrate as the template. Pores morphologies of the scaffolds relied on the previous ice crystal which had formed in templates and thus could be adjusted by altering the template structure. The decrease of gelatin in WS2 slurry transformed the bottom template from cell pore structure into the lamellar structure followed by improvement of lamellar orientation of the top Ti6Al4V scaffold. The pore widths of the scaffolds were in the range of 84-217 μm which were difficult to realize without the assisted template. The scaffolds also exhibited mechanical compatibility with bone tissues, indicating that the template-assisted freeze casting is a promising approach to fabricate macroporous Ti6Al4V implants. Keywords: Biomaterials; Porous materials; Freeze casting; Template-assisted; Ti6Al4V scaffolds; Macropores. 1.Introduction The ideal bone substitute requires favorable biocompatibility, suitable mechanical property and reasonable chemical resistance[1]. Porous structure could reduce “stress
Corresponding author. E-mail address: [email protected] (L. Zhang). 1
shielding effects” and offer space for cells proliferation, thus optimizing performances of the implant to match these requirements[2]. However, it seems that the lack of ductility is an inevitable problem for all porous implants. Comparing to ceramics, polymers and pure metal, porous Ti6Al4V scaffolds shows an excellent balance between stiffness and toughness in despite of the fabricating approaches[3-7]. Among those approaches, freeze casting is a promising one due to the high similarity (aligned, elongated sheet-like pores) between bone structure and the porous skeleton fabricated by this method[8]. Chino et al.[10] firstly fabricated titanium scaffolds with porosity of 57-67% by using unidirectional freeze casting but it was not suitable for implanting use due to fine pores and insufficient compressive strength. In the long term, the scaffold with large pore size exhibits better bone ingrowth ability which can enhance the bond between the implant and surrounding tissue ensuring its high reliability. Generally, a pore size of 100-400 μm and a porosity of 60-70% are the optimal range summarized from numerous researches [6, 7, 11]. Nevertheless, macroporous structure will put the scaffolds at high risk in the initial stage of implant placement because the strength and stiffness of scaffolds rapidly decrease as the pore size increased. To realize the biological and mechanical property at the same time, the pore structure is treated as a crucial issue to be investigated [11, 12]. It was found that the lamellar structure was quite superior to others [8]. The strong anisotropy of the lamellar structure could be the key point to offer enough strength for macroporous materials. As a solvent, albeit water shows a significant advantage in the fabrication of aligned and elongated pore 2
structures, the drawback that the titanium scaffold aperture is almost smaller than 100 μm cannot be ignored[5, 18]. How to enhance the pore size and porosity of the material while ensuring mechanical strength to meet the biomedical application requirement remains in water-based freeze casting of titanium scaffolds. During freeze casting, in addition to temperature, solid loading, binder content, etc., particle packing behavior and the morphology of the solidified fluid are affected by the particle-particle interactions, and different particles form structures with diverse pore morphology[19]. Our previous research indicated that macroporous WS2 scaffolds could be routinely obtained by the water-based freeze casting process, which differed from titanium[20]. Thus, in this work, pre-frozen WS2 substrate was used as a template to promote the growth of ice crystals in the titanium layer. The ice crystals firstly nucleated and grew in the WS2 layer, and then entered the titanium layer and continued to grow. So, the macroporous Ti6Al4V scaffolds were fabricated during this process, and its morphology could be controlled. Moreover, the pore morphology, phase composition and mechanical property of Ti6Al4V scaffolds were characterized, as well as the impacts of WS2 template on Ti6Al4V scaffolds. 2. Experiment and method Commercial Ti6Al4V and WS2 powders were used as raw materials while the gelatin and polyvinylpyrrolidone were chosen as the binder and dispersant, respectively. 3 vol.% WS2 suspensions with a series of gelatin content (1, 3, 5 wt.%) were poured into molds (58 × 58 × 60 mm) until the PDMS wedge (slope angle: 15 °) had been covered. Then, the WS2 slurries were frozen at -15 ℃ to achieve the assisted 3
templates. Subsequently, the residual space of the mold was slowly filled by 20 vol.% Ti6Al4V slurry with gelatin content of 2 wt.%. After the slurry was totally frozen, samples were freeze-dried for 40 h. WS2 templates were cut off, and the remaining part firstly degreased at 400 ℃ for 2 h then finally sintered at 1300 ℃ for 2 h in a vacuum furnace. The phase composition was identified by X-ray diffraction (XRD: Rigaku D/max 2500VB, Japan). Scanning electron microscopy (SEM: Quanta FEG 250, USA) was applied to analyze the microstructure of samples. The structure parameters were obtained by analyzing SEM images with Nano Measurer (Software, China). The total porosity was measured through the Archimedes method. Compressive test performed for the cube sample (10 × 10 × 10 mm) on a test system (INSTRON 3369, USA) at a constant displacement rate of 0.5 mm/min. 3. Results and discussion
Fig.1. (a) Phase composition and (b) vertical section microtopography of Ti6Al4V scaffolds
Fig.1a characterized the phase composition of the raw Ti6Al4V powder and sintered sample. No other phase but only Ti phase (JCPDS: 44-1294) was detected in both patterns, indicating that pure scaffolds had been obtained. Fig.1b presented a typical 4
microstructure of sintered scaffolds at vertical section, indexing highly oriented pore structure was formed.
Fig.2. SEM images of the cross-section of (a-c) porous Ti6Al4V fabricated on different WS2 template and (d-f) WS2 template with 1, 3, 5 wt.% gelatin content.
Fig.2 showed three distinct pore structures of the sintered scaffolds and the microstructures of those assisted templates were displayed at the corner. Ti6Al4V particles were rearranged by the promotion of the ice crystals which extended from the WS2 template. Thus, the microstructures of Ti6Al4V scaffolds were similar to their templates. WS2 templates with different gelatin contents exhibited three typical morphologies, which indicated that the morphologies of preformed ice crystals were quite different. Lamellar pores and a single wall structure were generated with the WS2 slurry containing 1 wt.% gelatin (Fig.2d), which helped the Ti6Al4V scaffolds to form a long-range order lamellar and macroporous structure (Fig.2a). When gelatin increased to 3 wt.%, the WS2 layers maintained the lamellar structure but some 5
bridges appeared (Fig.2e) causing a narrowed pore structure in Fig. 2b. Meanwhile, the titanium bridges linking neighbored titanium walls were widely observed. As the addition of gelatin approaching 5 wt.%, the lamellar structure had been replaced by cell pore structure (Fig.2f). This change showed a great influence on the pore structure of Ti6Al4V scaffolds. Although the lamellar structures remained in most of regions of porous Ti6Al4V, the long-range order was destructed (Fig.2c). The similarity between porous Ti6Al4V scaffold and its assisted WS2 template indicated that the pore structure could be effectively regulated by adjusting the microstructure of the preformed template. Table 1 Porosity, wall size and pore width of the Ti6Al4V samples
Sample
1
2
3
Gelatin content of WS2 template (wt.%) Porosity (%) Wall size (μm) Pore width (μm)
1 59.6±3.0 60±24 217±45
3 61.0±2.4 74±16 145±34
5 60.0±1.7 43±14 84±29
Table 1 lists the structural parameters of Ti6Al4V samples obtained from the Archimedes method and Nano Measurers software. The pore width dwindled from 217±45 to 84±29 μm with increase of gelatin used in WS2 template while the porosity was maintained at about 60 %. Mechanical properties of Ti6Al4V scaffolds were evaluated by compressive test along the ice growth direction. Fig.3a presented the stress-strain curves during the test and the compressive strength and elasticity modulus of each sample was measured from its curve. The compressive strength was in the range of 142.24±9.55 to 57.34±1.19 MPa, and elasticity modulus varied within the range of 5.05±0.23 to 2.86±0.32 GPa. Fig.3b showed comparisons of mechanical properties among the Ti6Al4V scaffolds 6
and revealed the relationship between the pore structure and mechanical properties. Sample 1 and 2 achieved better performance, even if their pores were about several times than the size of Sample 3, which indicated that the improvement of compressive strength was mainly benefited from long-range order lamellar structure.
Fig.3 Mechanical properties of three samples (a) compressive stress-strain curves, (b) compressive strength and elasticity modulus.
4. Conclusions We present a demonstration of template-assisted strategy to fabricate macroporous and long-range order lamellar Ti6Al4V scaffolds. Using the assisted template, the pore width of Ti6Al4V scaffolds which produced by water-based freeze casting can reach 217±45 μm. It was observed a structural similarity between the sample and the template, including morphology and orientation. By preforming ice crystals with the template, this strategy provides a new idea to design and construct porous scaffolds in freeze casting. The novel method is efficacious for the fabrication and optimization of a large-scale lamellar scaffold that it is expected to promote the application of porous titanium materials in biomedicine. Acknowledgments This research was supported by the National Nature Science Foundation of China (No. 7
51674304). References [1] G. Ryan, A. Pandit, D.P. Apatsidis, Biomaterials 27(13) (2006) 2651-70. [2] H.-C. Hsu, S.-C. Wu, S.-K. Hsu, M.-S. Tsai, T.-Y. Chang, W.-F. Ho, Materials & Design 47 (2013) 21-26. [3] Z. Esen, Ş. Bor, Materials Science and Engineering: A 528(7-8) (2011) 3200-3209. [4] M.A. Surmeneva, R.A. Surmenev, E.A. Chudinova, A. Koptioug, M.S. Tkachev, S.N. Gorodzha, L.-E. Rännar, Materials & Design 133 (2017) 195-204. [5] L. Yan, J. Wu, L. Zhang, X. Liu, K. Zhou, B. Su, Mater. Sci. Eng. C Mater. Biol. Appl. 75 (2017) 335-340. [6] J. Li, Z. Li, Y. Shi, H. Wang, R. Li, J. Tu, G. Jin, J. Mech. Behav. Biomed. Mater. 91 (2019) 149-158. [7] G. Lewis, J. Mater. Sci. Mater. Med. 24(10) (2013) 2293-325. [8] S. Deville, Advanced Engineering Materials 10(3) (2008) 155-169. [9] H.D. Jung, S.W. Yook, T.S. Jang, Y. Li, H.E. Kim, Y.H. Koh, Mater. Sci. Eng. C Mater. Biol. Appl. 33(1) (2013) 59-63. [10] Y. Chino, D.C. Dunand, Acta Materialia 56(1) (2008) 105-113. [11] B. Chang, W. Song, T. Han, J. Yan, F. Li, L. Zhao, H. Kou, Y. Zhang, Acta Biomater 33 (2016) 311-21. [12] R. Singh, P.D. Lee, R.J. Dashwood, T.C. Lindley, Materials Technology 25(3-4) (2013) 127-136. [13] N. Taniguchi, S. Fujibayashi, M. Takemoto, K. Sasaki, B. Otsuki, T. Nakamura, T. Matsushita, T. Kokubo, S. Matsuda, Mater. Sci. Eng. C Mater. Biol. Appl. 59 (2016) 690-701. [14] S. Van Bael, Y.C. Chai, S. Truscello, M. Moesen, G. Kerckhofs, H. Van Oosterwyck, J.P. Kruth, J. Schrooten, Acta Biomater 8(7) (2012) 2824-34. [15] J. Wieding, A. Jonitz, R. Bader, Materials 5(8) (2012) 1336-1347. [16] S.-W. Yook, H.-E. Kim, Y.-H. Koh, Materials Letters 63(17) (2009) 1502-1504. [17] B.-H. Yoon, Y.-H. Koh, C.-S. Park, H.-E. Kim, Journal of the American Ceramic Society 90(6) (2007) 1744-1752. [18] M. Mao, Y. Tang, K. Zhao, Z. Duan, C. Wu, Metals and Materials International 25(2) (2018) 508-515. [19] K.L. Scotti, D.C. Dunand, Progress in Materials Science 94 (2018) 243-305. [20] J. Wu, B. Luo, X. Liu, L. Zhang, Journal of Porous Materials 25(1) (2017) 37-43.
There are no conflicts of interest in this manuscript.
CRediT author statement 8
Lei Zhang: Conceptualization, Supervision, Project administration, Funding acquisition, Writing - Review & Editing Zhuyin Chen: Methodology, Investigation, Data Curation, Formal analysis, Visualization, Writing - Original Draft, Writing - Review & Editing Xinli Liu: Supervision, Writing - Review & Editing Ting Shen: Visualization, Formal analysis, Writing - Review & Editing Chuanzong Wu: Investigation
Declaration of interests
☐ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
☒The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:
9
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
1.
Macroporous Ti6Al4V scaffold was fabricated by template-assisted freeze casting.
2.
Morphology and orientation of pores are determined by the used template.
3.
Pore size decreases with increasing binder content in template slurry.
4.
The macroporous scaffolds exhibit mechanical compatibility with bone tissues.
10
S0167-577X(20)30079-3 https://doi.org/10.1016/j.matlet.2020.127374 MLBLUE 127374
To appear in:
Materials Letters
Received Date: Revised Date: Accepted Date:
28 July 2019 6 January 2020 17 January 2020
Please cite this article as: Z. Chen, X. Liu, T. Shen, C. Wu, L. Zhang, Template-assisted freeze casting of macroporous Ti6Al4V scaffolds with long-range order lamellar structure, Materials Letters (2020), doi: https:// doi.org/10.1016/j.matlet.2020.127374
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
© 2020 Published by Elsevier B.V.
Template-assisted freeze casting of macroporous Ti6Al4V scaffolds with long-range order lamellar structure Zhuyin Chen a, Xinli Liu b, Ting Shen a, Chuanzong Wu a, Lei Zhang a, a
State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083, PR China b
School of Materials Science and Engineering, Central South University, Changsha, Hunan, 410083, PR China
Abstract ： A modified water-based freeze casting to fabricate long-range order lamellar Ti6Al4V scaffolds with macropores and high porosity has been developed by using the pre-frozen WS2 substrate as the template. Pores morphologies of the scaffolds relied on the previous ice crystal which had formed in templates and thus could be adjusted by altering the template structure. The decrease of gelatin in WS2 slurry transformed the bottom template from cell pore structure into the lamellar structure followed by improvement of lamellar orientation of the top Ti6Al4V scaffold. The pore widths of the scaffolds were in the range of 84-217 μm which were difficult to realize without the assisted template. The scaffolds also exhibited mechanical compatibility with bone tissues, indicating that the template-assisted freeze casting is a promising approach to fabricate macroporous Ti6Al4V implants. Keywords: Biomaterials; Porous materials; Freeze casting; Template-assisted; Ti6Al4V scaffolds; Macropores. 1.Introduction The ideal bone substitute requires favorable biocompatibility, suitable mechanical property and reasonable chemical resistance[1]. Porous structure could reduce “stress
Corresponding author. E-mail address: [email protected] (L. Zhang). 1
shielding effects” and offer space for cells proliferation, thus optimizing performances of the implant to match these requirements[2]. However, it seems that the lack of ductility is an inevitable problem for all porous implants. Comparing to ceramics, polymers and pure metal, porous Ti6Al4V scaffolds shows an excellent balance between stiffness and toughness in despite of the fabricating approaches[3-7]. Among those approaches, freeze casting is a promising one due to the high similarity (aligned, elongated sheet-like pores) between bone structure and the porous skeleton fabricated by this method[8]. Chino et al.[10] firstly fabricated titanium scaffolds with porosity of 57-67% by using unidirectional freeze casting but it was not suitable for implanting use due to fine pores and insufficient compressive strength. In the long term, the scaffold with large pore size exhibits better bone ingrowth ability which can enhance the bond between the implant and surrounding tissue ensuring its high reliability. Generally, a pore size of 100-400 μm and a porosity of 60-70% are the optimal range summarized from numerous researches [6, 7, 11]. Nevertheless, macroporous structure will put the scaffolds at high risk in the initial stage of implant placement because the strength and stiffness of scaffolds rapidly decrease as the pore size increased. To realize the biological and mechanical property at the same time, the pore structure is treated as a crucial issue to be investigated [11, 12]. It was found that the lamellar structure was quite superior to others [8]. The strong anisotropy of the lamellar structure could be the key point to offer enough strength for macroporous materials. As a solvent, albeit water shows a significant advantage in the fabrication of aligned and elongated pore 2
structures, the drawback that the titanium scaffold aperture is almost smaller than 100 μm cannot be ignored[5, 18]. How to enhance the pore size and porosity of the material while ensuring mechanical strength to meet the biomedical application requirement remains in water-based freeze casting of titanium scaffolds. During freeze casting, in addition to temperature, solid loading, binder content, etc., particle packing behavior and the morphology of the solidified fluid are affected by the particle-particle interactions, and different particles form structures with diverse pore morphology[19]. Our previous research indicated that macroporous WS2 scaffolds could be routinely obtained by the water-based freeze casting process, which differed from titanium[20]. Thus, in this work, pre-frozen WS2 substrate was used as a template to promote the growth of ice crystals in the titanium layer. The ice crystals firstly nucleated and grew in the WS2 layer, and then entered the titanium layer and continued to grow. So, the macroporous Ti6Al4V scaffolds were fabricated during this process, and its morphology could be controlled. Moreover, the pore morphology, phase composition and mechanical property of Ti6Al4V scaffolds were characterized, as well as the impacts of WS2 template on Ti6Al4V scaffolds. 2. Experiment and method Commercial Ti6Al4V and WS2 powders were used as raw materials while the gelatin and polyvinylpyrrolidone were chosen as the binder and dispersant, respectively. 3 vol.% WS2 suspensions with a series of gelatin content (1, 3, 5 wt.%) were poured into molds (58 × 58 × 60 mm) until the PDMS wedge (slope angle: 15 °) had been covered. Then, the WS2 slurries were frozen at -15 ℃ to achieve the assisted 3
templates. Subsequently, the residual space of the mold was slowly filled by 20 vol.% Ti6Al4V slurry with gelatin content of 2 wt.%. After the slurry was totally frozen, samples were freeze-dried for 40 h. WS2 templates were cut off, and the remaining part firstly degreased at 400 ℃ for 2 h then finally sintered at 1300 ℃ for 2 h in a vacuum furnace. The phase composition was identified by X-ray diffraction (XRD: Rigaku D/max 2500VB, Japan). Scanning electron microscopy (SEM: Quanta FEG 250, USA) was applied to analyze the microstructure of samples. The structure parameters were obtained by analyzing SEM images with Nano Measurer (Software, China). The total porosity was measured through the Archimedes method. Compressive test performed for the cube sample (10 × 10 × 10 mm) on a test system (INSTRON 3369, USA) at a constant displacement rate of 0.5 mm/min. 3. Results and discussion
Fig.1. (a) Phase composition and (b) vertical section microtopography of Ti6Al4V scaffolds
Fig.1a characterized the phase composition of the raw Ti6Al4V powder and sintered sample. No other phase but only Ti phase (JCPDS: 44-1294) was detected in both patterns, indicating that pure scaffolds had been obtained. Fig.1b presented a typical 4
microstructure of sintered scaffolds at vertical section, indexing highly oriented pore structure was formed.
Fig.2. SEM images of the cross-section of (a-c) porous Ti6Al4V fabricated on different WS2 template and (d-f) WS2 template with 1, 3, 5 wt.% gelatin content.
Fig.2 showed three distinct pore structures of the sintered scaffolds and the microstructures of those assisted templates were displayed at the corner. Ti6Al4V particles were rearranged by the promotion of the ice crystals which extended from the WS2 template. Thus, the microstructures of Ti6Al4V scaffolds were similar to their templates. WS2 templates with different gelatin contents exhibited three typical morphologies, which indicated that the morphologies of preformed ice crystals were quite different. Lamellar pores and a single wall structure were generated with the WS2 slurry containing 1 wt.% gelatin (Fig.2d), which helped the Ti6Al4V scaffolds to form a long-range order lamellar and macroporous structure (Fig.2a). When gelatin increased to 3 wt.%, the WS2 layers maintained the lamellar structure but some 5
bridges appeared (Fig.2e) causing a narrowed pore structure in Fig. 2b. Meanwhile, the titanium bridges linking neighbored titanium walls were widely observed. As the addition of gelatin approaching 5 wt.%, the lamellar structure had been replaced by cell pore structure (Fig.2f). This change showed a great influence on the pore structure of Ti6Al4V scaffolds. Although the lamellar structures remained in most of regions of porous Ti6Al4V, the long-range order was destructed (Fig.2c). The similarity between porous Ti6Al4V scaffold and its assisted WS2 template indicated that the pore structure could be effectively regulated by adjusting the microstructure of the preformed template. Table 1 Porosity, wall size and pore width of the Ti6Al4V samples
Sample
1
2
3
Gelatin content of WS2 template (wt.%) Porosity (%) Wall size (μm) Pore width (μm)
1 59.6±3.0 60±24 217±45
3 61.0±2.4 74±16 145±34
5 60.0±1.7 43±14 84±29
Table 1 lists the structural parameters of Ti6Al4V samples obtained from the Archimedes method and Nano Measurers software. The pore width dwindled from 217±45 to 84±29 μm with increase of gelatin used in WS2 template while the porosity was maintained at about 60 %. Mechanical properties of Ti6Al4V scaffolds were evaluated by compressive test along the ice growth direction. Fig.3a presented the stress-strain curves during the test and the compressive strength and elasticity modulus of each sample was measured from its curve. The compressive strength was in the range of 142.24±9.55 to 57.34±1.19 MPa, and elasticity modulus varied within the range of 5.05±0.23 to 2.86±0.32 GPa. Fig.3b showed comparisons of mechanical properties among the Ti6Al4V scaffolds 6
and revealed the relationship between the pore structure and mechanical properties. Sample 1 and 2 achieved better performance, even if their pores were about several times than the size of Sample 3, which indicated that the improvement of compressive strength was mainly benefited from long-range order lamellar structure.
Fig.3 Mechanical properties of three samples (a) compressive stress-strain curves, (b) compressive strength and elasticity modulus.
4. Conclusions We present a demonstration of template-assisted strategy to fabricate macroporous and long-range order lamellar Ti6Al4V scaffolds. Using the assisted template, the pore width of Ti6Al4V scaffolds which produced by water-based freeze casting can reach 217±45 μm. It was observed a structural similarity between the sample and the template, including morphology and orientation. By preforming ice crystals with the template, this strategy provides a new idea to design and construct porous scaffolds in freeze casting. The novel method is efficacious for the fabrication and optimization of a large-scale lamellar scaffold that it is expected to promote the application of porous titanium materials in biomedicine. Acknowledgments This research was supported by the National Nature Science Foundation of China (No. 7
51674304). References [1] G. Ryan, A. Pandit, D.P. Apatsidis, Biomaterials 27(13) (2006) 2651-70. [2] H.-C. Hsu, S.-C. Wu, S.-K. Hsu, M.-S. Tsai, T.-Y. Chang, W.-F. Ho, Materials & Design 47 (2013) 21-26. [3] Z. Esen, Ş. Bor, Materials Science and Engineering: A 528(7-8) (2011) 3200-3209. [4] M.A. Surmeneva, R.A. Surmenev, E.A. Chudinova, A. Koptioug, M.S. Tkachev, S.N. Gorodzha, L.-E. Rännar, Materials & Design 133 (2017) 195-204. [5] L. Yan, J. Wu, L. Zhang, X. Liu, K. Zhou, B. Su, Mater. Sci. Eng. C Mater. Biol. Appl. 75 (2017) 335-340. [6] J. Li, Z. Li, Y. Shi, H. Wang, R. Li, J. Tu, G. Jin, J. Mech. Behav. Biomed. Mater. 91 (2019) 149-158. [7] G. Lewis, J. Mater. Sci. Mater. Med. 24(10) (2013) 2293-325. [8] S. Deville, Advanced Engineering Materials 10(3) (2008) 155-169. [9] H.D. Jung, S.W. Yook, T.S. Jang, Y. Li, H.E. Kim, Y.H. Koh, Mater. Sci. Eng. C Mater. Biol. Appl. 33(1) (2013) 59-63. [10] Y. Chino, D.C. Dunand, Acta Materialia 56(1) (2008) 105-113. [11] B. Chang, W. Song, T. Han, J. Yan, F. Li, L. Zhao, H. Kou, Y. Zhang, Acta Biomater 33 (2016) 311-21. [12] R. Singh, P.D. Lee, R.J. Dashwood, T.C. Lindley, Materials Technology 25(3-4) (2013) 127-136. [13] N. Taniguchi, S. Fujibayashi, M. Takemoto, K. Sasaki, B. Otsuki, T. Nakamura, T. Matsushita, T. Kokubo, S. Matsuda, Mater. Sci. Eng. C Mater. Biol. Appl. 59 (2016) 690-701. [14] S. Van Bael, Y.C. Chai, S. Truscello, M. Moesen, G. Kerckhofs, H. Van Oosterwyck, J.P. Kruth, J. Schrooten, Acta Biomater 8(7) (2012) 2824-34. [15] J. Wieding, A. Jonitz, R. Bader, Materials 5(8) (2012) 1336-1347. [16] S.-W. Yook, H.-E. Kim, Y.-H. Koh, Materials Letters 63(17) (2009) 1502-1504. [17] B.-H. Yoon, Y.-H. Koh, C.-S. Park, H.-E. Kim, Journal of the American Ceramic Society 90(6) (2007) 1744-1752. [18] M. Mao, Y. Tang, K. Zhao, Z. Duan, C. Wu, Metals and Materials International 25(2) (2018) 508-515. [19] K.L. Scotti, D.C. Dunand, Progress in Materials Science 94 (2018) 243-305. [20] J. Wu, B. Luo, X. Liu, L. Zhang, Journal of Porous Materials 25(1) (2017) 37-43.
There are no conflicts of interest in this manuscript.
CRediT author statement 8
Lei Zhang: Conceptualization, Supervision, Project administration, Funding acquisition, Writing - Review & Editing Zhuyin Chen: Methodology, Investigation, Data Curation, Formal analysis, Visualization, Writing - Original Draft, Writing - Review & Editing Xinli Liu: Supervision, Writing - Review & Editing Ting Shen: Visualization, Formal analysis, Writing - Review & Editing Chuanzong Wu: Investigation
Declaration of interests
☐ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
☒The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:
9
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
1.
Macroporous Ti6Al4V scaffold was fabricated by template-assisted freeze casting.
2.
Morphology and orientation of pores are determined by the used template.
3.
Pore size decreases with increasing binder content in template slurry.
4.
The macroporous scaffolds exhibit mechanical compatibility with bone tissues.
10