Ion Bean Etching on Ti-30Ta Alloy for Biomedical Application

Ion bean etching on Ti-30Ta Alloy for Biomedical Application

Patricia Capellato1,*, Nicholas A. Riedel2, John D. Williams2,Joao P.B. Machado3, Ketul C. Popat2,4 and Ana P. R. Alves Claro1

1Department of Materials, Faculty of Engineering Guaratinguetá, Sao Paulo State University- UNESP, Av. Ariberto Pereira da Cunha,333, Pedregulho, CEP 12516-410, Guaratinguetá, SP, Brazil.

2Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523, USA.

3 Associated Laboratory of Sensors and Materials, LAS, National Institute for Space Research, INPE, Av. Dos Astronautas, 1758, Jd. Granja, CEP 12227-010, São Jose dos Campos, SP, Brazil.

4 School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA

*Author of correspondence:

E-mail:

Abstract

Titanium and titanium alloys are currently being used for clinical biomedical applications due to their high strength, corrosion resistance and elastic modulus. However, these materials have recently been shown to exhibit ion release and poor physiological integration that may result in fibrous encapsulation and further biomaterial rejection. In order to be a successful replacement for bone current approaches for enhancing the mechanical and biological properties of Ti was alloyed Ti with Ta due to it provides greatly improved mechanical properties which include fracture toughness and workability. Studies have shown techniques such ion beam etching, heat and alkaline treatment, SBF coatings and anodization to promote altered cellular response on Ti and Ti- alloys. In this study Ti-30Ta alloy was investigated ion beam etching. The SEM was used to investigate the topography, EDS the chemical composition, and surface energy was evaluate with contact angle analyze due to the topography have effect on protein adsorption, platelet adhesion, blood coagulation and bacterial adhesion. This study concludes Ti-30Ta alloy substrate with ion beam etching was not favorable for biomedical application.

Key Words: Biocompatibility; Ti-30Ta alloy; Ion beam etching.

1. Introduction

Metallic materials have been used as implantable for orthopedic and dental implants.The interaction between the implant surface and the tissue plays an important role on the success of this implantable device[3, 7, 29].Several studies have shown that by modifying the surface at a nanoscale or a microscale can alter cellular response[20, 30-32]. Studies have shown techniques such ion beam etching[33, 34]to promote altered cellular response on Ti and Ti-alloys. One effective parameter to evaluate the biological response of the metallic biomaterials is investigated the wettability of the surface of this material due to the topography have effect on protein adsorption, platelet adhesion, blood coagulation and bacterial adhesion[42-45].

In this study, thesubstrate surface of the Ti-30Ta alloy was altered by topographical surface modification.The Ti-30Ta alloy substrates were modified with ion beam etching. Following techniques were used for characterized all groups:scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and contact angle analyze.

2. Materials and Method

Ti and Tawerecombined by a melting process, homogenized in a vacuum, cold-worked by a rotary swaging process and cut in discs. The Ti-30Ta modified byetching the alloy surface to oblique angle oxygen ion beam by increasing the oxygenation of the near surface regions. Etching was done with a 16 cm ion source in a low-pressure environment (approximately 1.6 x 10-4 Torr). Gas flow rates through the source and neutralizer were 20 sccm O2 and 8 sccm Ar respectively. An energetic ion beam of 1200 eV ions with a beam current of 200 mA was used for a 3 hour etch. This beam consisted primarily of oxygen ions though it is possible that minute amounts of background Ar gas could diffuse into the source, ionize and be included. The substrates were placed on an inclined holder so the resulting angle of ion incidence was approximately 75 degrees from the surface normal[33].

2.1Physical characterization

The Ti-30Ta alloy substrates surfaceswere examined before and after the surface modification.The surface topography of the substrates was characterized using a JEOL JSM-6500FESEM.The surface elemental composition of the Ti-30Ta alloy substrates was further characterized with energy-dispersive X-ray spectroscopy (EDS, JSM- 6500F SEM). Wettability of the modified surfaces weredetermined by measuring water contact angle (FTA1000B Class,First Ten Angstroms, Inc). A2 µl droplet of distilled water was dropped onthe surface. Immediately after this the droplet images captured using a camera. The image were then processed withtheaccompanying Fta32 software determine give contact angle andthe droplet volume. All the studies were conducted for minimum 6 samples to ensure appropriate statistical variability.

3. Results and Discussion

Fig. 1 shows SEM images.The results showformation of nano-scale spheroids with a wavy surface architecture. Further, the results indicate that the ion etching did not significantly alter the surface. It seems that etching at 1200eV was not enough to significantly change the surface topography[33].EDS spectra for group 1showedpeaks for titanium and tantalum.

The Fig. 2 shows contact angle measurements Ti-30Ta control group and Ti-30Ta etch. The results indicate following order of surface hydrophilicity:

Group 1 ˃ Group 5

This behavior is extremely important since cell and bacterial adhesion, protein adsorption, platelet adhesion and activation and blood coagulation may be affected. The materials for biomedical application need to be more hydrophilic since they have higher surface energy which is desirable for biological interaction.[43, 45, 49].

4. Conclusion

In this study, the Ti-30Ta alloy substrates were modified by ion beam etching. SEM results show different structure on the surface . EDS spectra identified similarity on Group 1 and 5. The results presented here a little alteration in the topography on the substrate surfaces.Overall the contact angle showsTi-30Ta etchmore hydrophobic than Ti-30Ta controlThis study concludes Ti-30Ta alloy substrate with ion beam etching was not favorable for biomedical application.

5. Acknowledgements

Partial funding support for this work was provided by Brazilian agencies CNPq via grant Doctored sandwich, project number 201271/2010-9. The authors thank Patrick McCurdyfor your assistance.

References

[1] Bannon BPM, E E Titanium Alloys in Surgical Implants. Titanium Alloys for Biomaterial Application: an Overview. Phoenix, Ariz ; U.S.A1983. p. pp. 7-15.

[2] Ellingsen JE, Thomsen P, Lyngstadaas SP. Advances in dental implant materials and tissue regeneration. Periodontology 2000. 2006;41:136-56.

[3] Geetha M, Singh AK, Asokamani R, Gogia AK. Ti based biomaterials, the ultimate choice for orthopaedic implants - A review. Progress in Materials Science. 2009;54:397-425.

[4] Liu X, Chu PK, Ding C. Surface modification of titanium, titanium alloys, and related materials for biomedical applications. Materials Science and Engineering: R: Reports. 2004;47:49-121.

[5] Niinomi M. Mechanical biocompatibilities of titanium alloys for biomedical applications. Journal of the Mechanical Behavior of Biomedical Materials. 2008;1:30-42.

[6] Wang K. The use of titanium for medical applications in the USA. Materials Science and Engineering: A. 1996;213:134-7.

[7] Galante JO, Lemons J, Spector M, Wilson PD, Wright TM. The biologic effects of implant materials. Journal of Orthopaedic Research. 1991;9:760-75.

[8] Cristina Palma-Carrió LM-F, David Peñarrocha-Oltra , María A. Peñarrocha-Diago,, Peñarrocha-Diago M. Risk factors associated with early failure of dental implants. A literature review. Med Oral Patol Oral Cir Bucal. 2011;16:514-7.

[9] Zhou Y-L, Niinomi M. Ti-25Ta alloy with the best mechanical compatibility in Ti-Ta alloys for biomedical applications. Materials Science and Engineering: C. 2009;29:1061-5.

[10] Zhou Y-L, Niinomi M. Microstructures and mechanical properties of Ti-50mass% Ta alloy for biomedical applications. Journal of Alloys and Compounds. 2008;466:535-42.

[11] Zhou Y-L, Niinomi M, Akahori T. Changes in mechanical properties of Ti alloys in relation to alloying additions of Ta and Hf. Materials Science and Engineering: A. 2008;483-484:153-6.

[12] Zhou YL, Niinomi M, Akahori T. Decomposition of martensite [alpha]'' during aging treatments and resulting mechanical properties of Ti-Ta alloys. Materials Science and Engineering A. 2004;384:92-101.

[13] Zhou YL, Niinomi M, Akahori T. Effects of Ta content on Young's modulus and tensile properties of binary Ti-Ta alloys for biomedical applications. Materials Science and Engineering A. 2004;371:283-90.

[14] Niinomi M. Recent metallic materials for biomedical applications. Metallurgical and Materials Transactions A. 2002;33:477-86.

[15] Miyazaki T, Kim H-M, Miyaji F, Kokubo T, Kato H, Nakamura T. Bioactive tantalum metal prepared by NaOH treatment. Journal of Biomedical Materials Research. 2000;50:35-42.

[16] Miyazaki T, Kim HM, Kokubo T, Ohtsuki C, Kato H, Nakamura T. Enhancement of bonding strength by graded structure at interface between apatite layer and bioactive tantalum metal. Journal of Materials Science: Materials in Medicine. 2002;13:651-5.

[17] Miyazaki T, Kim HM, Kokubo T, Miyaji F, Kato H, Nakamura T. Effect of thermal treatment on apatite-forming ability of NaOH-treated tantalum metal. Journal of Materials Science: Materials in Medicine. 2001;12:683-7.

[18] Mareci D, Chelariu R, Gordin D-M, Ungureanu G, Gloriant T. Comparative corrosion study of Ti-Ta alloys for dental applications. Acta Biomaterialia. 2009;5:3625-39.

[19] Wei D, Zhou Y, Jia D, Wang Y. Structure of calcium titanate/titania bioceramic composite coatings on titanium alloy and apatite deposition on their surfaces in a simulated body fluid. Surface and Coatings Technology. 2007;201:8715-22.

[20] Variola F, Vetrone F, Richert L, Jedrzejowski P, Yi J-H, Zalzal S, et al. Improving Biocompatibility of Implantable Metals by Nanoscale Modification of Surfaces: An Overview of Strategies, Fabrication Methods, and Challenges. Small. 2009;5:996-1006.

[21] Eisenbarth E, Velten D, Müller M, Thull R, Breme J. Biocompatibility of [beta]-stabilizing elements of titanium alloys. Biomaterials. 2004;25:5705-13.

[22] Jianting G, Ranucci D, Gherardi F. Precipitation of β phase in the γ’ particles of nickel-base superalloy. Metallurgical and Materials Transactions A. 1984;15:1331-4.

[23] Cai Z, Koike M, Sato H, Brezner M, Guo Q, Komatsu M, et al. Electrochemical characterization of cast Ti-Hf binary alloys. Acta Biomaterialia. 2005;1:353-6.

[24] Gill P, Munroe N, Pulletikurthi C, Pandya S, Haider W. Effect of Manufacturing Process on the Biocompatibility and Mechanical Properties of Ti-30Ta Alloy. Journal of Materials Engineering and Performance. 2011;20:819-23.

[25] Zhou YL, Niinomi M, Akahori T, Fukui H, Toda H. Corrosion resistance and biocompatibility of Ti-Ta alloys for biomedical applications. Materials Science and Engineering A. 2005;398:28-36.

[26] Tong Y, Guo B, Zheng Y, Chung C, Ma L. Effects of Sn and Zr on the Microstructure and Mechanical Properties of Ti-Ta-Based Shape Memory Alloys. Journal of Materials Engineering and Performance. 2011;20:762-6.

[27] Gloriant T, Texier G, Prima F, Laillé D, Gordin DM, Thibon I, et al. Synthesis and Phase Transformations of Beta Metastable Ti-Based Alloys Containing Biocompatible Ta, Mo and Fe Beta-Stabilizer Elements. Advanced Engineering Materials. 2006;8:961-5.

[28] Dobromyslov A, Dolgikh G, Dutkevich Y, Trenogina T. Phase and structural transformations in Ti-Ta alloys. The Physics of Metals and Metallography. 2009;107:502-10.

[29] Smith BS, Yoriya S, Grissom L, Grimes CA, Popat KC. Hemocompatibility of titania nanotube arrays. Journal of Biomedical Materials Research Part A. 2010;95A:350-60.

[30] Wang XJ, Li YC, Lin JG, Yamada Y, Hodgson PD, Wen CE. In vitro bioactivity evaluation of titanium and niobium metals with different surface morphologies. Acta Biomaterialia. 2008;4:1530-5.

[31] Habibovic P, Sees TM, van den Doel MA, van Blitterswijk CA, de Groot K. Osteoinduction by biomaterials—Physicochemical and structural influences. Journal of Biomedical Materials Research Part A. 2006;77A:747-62.

[32] Kokubo T, Kim H-M, Kawashita M. Novel bioactive materials with different mechanical properties. Biomaterials. 2003;24:2161-75.

[33] Nicholas A. Riedel JDW, Ketul C. Popat. Ion Beam etching titanium for enhanced osteoblast response. Journal Material Science. 2011;46:6087-95.

[34] Martínez E, Engel E, Planell JA, Samitier J. Effects of artificial micro- and nano-structured surfaces on cell behaviour. Annals of Anatomy - Anatomischer Anzeiger. 2009;191:126-35.

[35] Kim H-M, Miyaji F, Kokubo T, Nakamura T. Preparation of bioactive Ti and its alloys via simple chemical surface treatment. Journal of Biomedical Materials Research. 1996;32:409-17.

[36] Kato H, Nakamura T, Nishiguchi S, Matsusue Y, Kobayashi M, Miyazaki T, et al. Bonding of alkali- and heat-treated tantalum implants to bone. Journal of Biomedical Materials Research. 2000;53:28-35.

[37] Miyazaki T, Kim H-M, Kokubo T, Ohtsuki C, Kato H, Nakamura T. Mechanism of bonelike apatite formation on bioactive tantalum metal in a simulated body fluid. Biomaterials. 2002;23:827-32.

[38] Barrere F, van Blitterswijk CA, de Groot K, Layrolle P. Influence of ionic strength and carbonate on the Ca-P coating formation from SBF×5 solution. Biomaterials. 2002;23:1921-30.

[39] Han-Cheol C. Nanotubular surface and morphology of Ti-binary and Ti-ternary alloys for biocompatibility. Thin Solid Films. 2011;519:4652-7.

[40] Tsuchiya H, Akaki T, Nakata J, Terada D, Tsuji N, Koizumi Y, et al. Anodic oxide nanotube layers on Ti–Ta alloys: Substrate composition, microstructure and self-organization on two-size scales. Corrosion Science. 2009;51:1528-33.

[41] Allam NK, Feng XJ, Grimes CA. Self-Assembled Fabrication of Vertically Oriented Ta2O5 Nanotube Arrays, and Membranes Thereof, by One-Step Tantalum Anodization. Chemistry of Materials. 2008;20:6477-81.

[42] Choee J-H, Lee SJ, Lee YM, Rhee JM, Lee HB, Khang G. Proliferation rate of fibroblast cells on polyethylene surfaces with wettability gradient. Journal of Applied Polymer Science. 2004;92:599-606.

[43] Zhao G, Schwartz Z, Wieland M, Rupp F, Geis-Gerstorfer J, Cochran DL, et al. High surface energy enhances cell response to titanium substrate microstructure. Journal of Biomedical Materials Research Part A. 2005;74A:49-58.

[44] Le Guéhennec L, Soueidan A, Layrolle P, Amouriq Y. Surface treatments of titanium dental implants for rapid osseointegration. Dental Materials. 2007;23:844-54.

[45] Escada ALA, Rodrigues Jr D, Machado JPB, Claro APRA. Surface characterization of Ti-7.5Mo alloy modified by biomimetic method. Surface and Coatings Technology. 2010;205:383-7.

[46] Wei M, Uchida M, Kim H-M, Kokubo T, Nakamura T. Apatite-forming ability of CaO-containing titania. Biomaterials. 2002;23:167-72.

[47] Ho W-F, Chen W-K, Wu S-C, Hsu H-C. Structure, mechanical properties, and grindability of dental Ti–Zr alloys. Journal of Materials Science: Materials in Medicine. 2008;19:3179-86.

[48] Wen HB, Wolke JGC, de Wijn JR, Liu Q, Cui FZ, de Groot K. Fast precipitation of calcium phosphate layers on titanium induced by simple chemical treatments. Biomaterials. 1997;18:1471-8.

[49] Zinger O, Anselme K, Denzer A, Habersetzer P, Wieland M, Jeanfils J, et al. Time-dependent morphology and adhesion of osteoblastic cells on titanium model surfaces featuring scale-resolved topography. Biomaterials. 2004;25:2695-711.

Fig. 1: SEM images (left) and EDS scans (right) for Ti-30Ta alloy etch taking in 5000X magnificence.

Fig. 2.Contact angle measurements on surfaces of control group and ion bean etching.

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