{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,16]],"date-time":"2026-04-16T06:07:27Z","timestamp":1776319647968,"version":"3.50.1"},"reference-count":40,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2024,7,6]],"date-time":"2024-07-06T00:00:00Z","timestamp":1720224000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Warsaw University of Technology"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Micromachines"],"abstract":"<jats:p>Background: The NiTi alloy, known for its shape memory and superelasticity, is increasingly used in medicine. However, its high nickel content requires enhanced biocompatibility for long-term implants. Low-temperature plasma treatments under glow-discharge conditions can improve surface properties without compromising mechanical integrity. Methods: This study explores the surface modification of a NiTi alloy by oxidizing it in low-temperature plasma. We examine the impact of process temperatures and sample preparation (mechanical grinding and polishing) on the structure of the produced titanium oxide layers. Surface properties, including topography, morphology, chemical composition, and bioactivity, were analyzed using TEM, SEM, EDS, and an optical profilometer. Bioactivity was assessed through the deposition of calcium phosphate in simulated body fluid (SBF). Results: The low-temperature plasma oxidization produced titanium dioxide layers (29\u201355 nm thick) with a predominantly nanocrystalline rutile structure. Layer thickness increased with extended processing time and higher temperatures (up to 390 \u00b0C), though the relationship was not linear. Higher temperatures led to thicker layers with more precipitates and inhomogeneities. The oxidized layers showed increased bioactivity after 14 and 30 days in SBF. Conclusions: Low-temperature plasma oxidation produces bioactive titanium oxide layers on NiTi alloys, with a structure and properties that can be tuned through process parameters. This method could enhance the biocompatibility of NiTi alloys for medical implants.<\/jats:p>","DOI":"10.3390\/mi15070886","type":"journal-article","created":{"date-parts":[[2024,7,8]],"date-time":"2024-07-08T14:40:50Z","timestamp":1720449650000},"page":"886","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Structure and Properties of Bioactive Titanium Dioxide Surface Layers Produced on NiTi Shape Memory Alloy in Low-Temperature Plasma"],"prefix":"10.3390","volume":"15","author":[{"given":"Justyna","family":"Witkowska","sequence":"first","affiliation":[{"name":"Faculty of Materials Science and Engineering, Warsaw University of Technology, 02-507 Warsaw, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5881-8380","authenticated-orcid":false,"given":"Tomasz","family":"Borowski","sequence":"additional","affiliation":[{"name":"Faculty of Materials Science and Engineering, Warsaw University of Technology, 02-507 Warsaw, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5524-7305","authenticated-orcid":false,"given":"Krzysztof","family":"Kulikowski","sequence":"additional","affiliation":[{"name":"Faculty of Materials Science and Engineering, Warsaw University of Technology, 02-507 Warsaw, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3800-8844","authenticated-orcid":false,"given":"Karol","family":"Wunsch","sequence":"additional","affiliation":[{"name":"Faculty of Materials Science and Engineering, Warsaw University of Technology, 02-507 Warsaw, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1807-0149","authenticated-orcid":false,"given":"Jerzy","family":"Morgiel","sequence":"additional","affiliation":[{"name":"Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 30-059 Krakow, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jerzy","family":"Sobiecki","sequence":"additional","affiliation":[{"name":"Faculty of Materials Science and Engineering, Warsaw University of Technology, 02-507 Warsaw, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tadeusz","family":"Wierzcho\u0144","sequence":"additional","affiliation":[{"name":"Faculty of Materials Science and Engineering, Warsaw University of Technology, 02-507 Warsaw, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2024,7,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1661","DOI":"10.1016\/j.actbio.2012.01.018","article-title":"A new look at biomedical Ti-based shape memory alloys","volume":"8","author":"Biesiekierski","year":"2012","journal-title":"Acta Biomater."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1016\/j.msea.2003.10.326","article-title":"Medical shape memory alloy applications\u2014The market and its products","volume":"378","author":"Morgan","year":"2004","journal-title":"Mater. Sci. Eng. A"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Brunette, D.M., Tengvall, P., Textor, M., and Thomsen, P. (2001). Titanium in Medicine: Material Science, Surface Science, Engineering, Biological Responses and Medical Applications, Springer.","DOI":"10.1007\/978-3-642-56486-4"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"320","DOI":"10.1002\/jbm.b.30545","article-title":"In vitro corrosion study by EIS of an equiatomic NiTi alloy and an implant quality AISI 316 stainless steel","volume":"79","author":"Rondelli","year":"2006","journal-title":"J. Biomed. Mater. Res. Part B Appl. Biomater."},{"key":"ref_5","unstructured":"Otsuka, K., and Wayman, C.M. (1998). Shape Memory Materials, Cambridge University Press."},{"key":"ref_6","first-page":"446","article-title":"Biocompatibility and mechanical properties of Ti\u2013Ni\u2013Cu shape memory alloy fabricated by powder metallurgy","volume":"72","author":"Wu","year":"2017","journal-title":"Mater. Sci. Eng. C"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"49","DOI":"10.1016\/j.mser.2004.11.001","article-title":"Surface modification of titanium, titanium alloys, and related materials for biomedical applications","volume":"47","author":"Liu","year":"2005","journal-title":"Mater. Sci. Eng. R Rep."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"879","DOI":"10.3390\/mi6070879","article-title":"Micromachined Shape-Memory-Alloy Microactuators and Their Application in Biomedical Devices","volume":"6","author":"Zainal","year":"2015","journal-title":"Micromachines"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"245","DOI":"10.1109\/84.679390","article-title":"Thin-film shape-memory alloy actuated micropumps","volume":"7","author":"Benard","year":"1998","journal-title":"J. Microelectromechanical Syst."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Miyazaki, S., Fu, Y.Q., and Huang, W.M. (2009). TiNi thin film shape memory alloys for optical sensing applications. Thin Film Shape Memory Alloys: Fundamentals and Device Applications, Cambridge University Press.","DOI":"10.1017\/CBO9780511635366"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1080\/00150190490460867","article-title":"A Comparison of PZT-Based and TiNi Shape Memory Alloy-Based MEMS Microactuators","volume":"306","author":"Lai","year":"2004","journal-title":"Ferroelectrics"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"2208517","DOI":"10.1002\/adma.202208517","article-title":"Shape Memory Alloy (SMA) Actuators: The Role of Material, Form, and Scaling Effects","volume":"35","author":"Kim","year":"2023","journal-title":"Adv. Mater."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"745","DOI":"10.1016\/j.msec.2004.08.018","article-title":"Metal ion release from metal implants","volume":"24","author":"Hanawa","year":"2004","journal-title":"Mater. Sci. Eng. C"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"3659","DOI":"10.1007\/s10853-005-0448-7","article-title":"Nickel ion release from orthodontic NiTi wires under simulation of realistic in-situ conditions","volume":"40","author":"Arndt","year":"2005","journal-title":"J. Mater. Sci."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1016\/S1040-8428(01)00214-1","article-title":"Nickel essentiality, toxicity, and carcinogenicity","volume":"42","author":"Denkhaus","year":"2002","journal-title":"Crit. Rev. Oncol."},{"key":"ref_16","unstructured":"Eliaz, N., and Sridhar, T.M. (2018). Biocompatibility of Nickel and its Alloys. Nickel and Chromium Nanoparticles, Springer."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"497","DOI":"10.1016\/j.msec.2003.11.001","article-title":"Bioactive NiTi shape memory alloy used as bone bonding implants","volume":"24","author":"Chen","year":"2004","journal-title":"Mater. Sci. Eng. C"},{"key":"ref_18","first-page":"1148","article-title":"The effect of a TiN coating on the biocompatibility of NiTi shape memory alloy","volume":"805","author":"Huang","year":"2019","journal-title":"J. Alloys Compd."},{"key":"ref_19","first-page":"95965","article-title":"Improvement of corrosion resistance, bioactivity and cell response of NiTi alloy by graphene oxide\/hydroxyapatite coating","volume":"6","author":"Gong","year":"2016","journal-title":"RSC Adv."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1720","DOI":"10.1016\/j.diamond.2006.03.004","article-title":"Effect of diamond-like carbon (DLC) on the properties of the NiTi alloys","volume":"15","author":"Sui","year":"2006","journal-title":"Diam. Relat. Mater."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"127","DOI":"10.4028\/www.scientific.net\/SSP.163.127","article-title":"Structure of Low Temperature Nitrided\/Oxidized Layer Formed on NiTi Shape Memory Alloy","volume":"163","author":"Goryczka","year":"2010","journal-title":"Solid State Phenom."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1016\/j.micron.2018.07.009","article-title":"Multi-scale characterization and biological evaluation of composite surface layers produced under glow discharge conditions on NiTi shape memory alloy for potential cardiological application","volume":"114","author":"Chlanda","year":"2018","journal-title":"Micron"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"24","DOI":"10.1016\/j.apsusc.2014.07.109","article-title":"Structure and properties of nitrided surface layer produced on NiTi shape memory alloy by low temperature plasma nitriding","volume":"334","author":"Czarnowska","year":"2015","journal-title":"Appl. Surf. Sci."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"2233","DOI":"10.2217\/nnm-2017-0092","article-title":"Hybrid a-CNH+TiO2 +TiN-type surface layers produced on NiTi shape memory alloy for cardiovascular applications","volume":"12","author":"Witkowska","year":"2017","journal-title":"Nanomedicine"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"980","DOI":"10.1016\/j.actbio.2007.03.006","article-title":"Formation and adhesion of biomimetic hydroxyapatite deposited on titanium substrates","volume":"3","author":"Forsgren","year":"2007","journal-title":"Acta Biomater."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"2907","DOI":"10.1016\/j.biomaterials.2006.01.017","article-title":"How useful is SBF in predicting in vivo bone bioactivity?","volume":"27","author":"Kokubo","year":"2006","journal-title":"Biomaterials"},{"key":"ref_27","first-page":"170","article-title":"The control of human mesenchymal cell differentiation using nanoscale symmetry and disorder","volume":"6","author":"Dalby","year":"2014","journal-title":"Nat. Mater."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"363","DOI":"10.1615\/CritRevBiomedEng.v40.i5.10","article-title":"Bone tissue engineering: Recent advances and challenges","volume":"40","author":"Amini","year":"2013","journal-title":"Crit. Rev. Biomed. Eng."},{"key":"ref_29","first-page":"677","article-title":"Role of non-canonical Wnt signaling in osteoblast maturation on microstructured titanium surfaces","volume":"99","author":"Hyzy","year":"2019","journal-title":"Acta Biomater."},{"key":"ref_30","first-page":"199","article-title":"Early bone healing around different implant bulk designs and surgical techniques: A study in dogs","volume":"46","author":"Coelho","year":"2019","journal-title":"J. Clin. Periodontol."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Zhang, Y., Fan, Z., Xing, Y., Jia, S., Mo, Z., and Gong, H. (2022). Effect of microtopography on osseointegration of implantable biomaterials and its modification strategies. Front. Bioeng. Biotechnol., 10.","DOI":"10.3389\/fbioe.2022.981062"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"406","DOI":"10.2174\/1874210601812010406","article-title":"Overview of Calcium Phosphates used in Biomimetic Oral Care","volume":"12","author":"Meyer","year":"2018","journal-title":"Open Dent. J."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"121","DOI":"10.4161\/biom.18790","article-title":"Calcium orthophosphates: Occurrence, properties, biomineralization, pathological calcification and biomimetic applications","volume":"1","author":"Dorozhkin","year":"2011","journal-title":"Biomatter"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1016\/S0022-0248(99)00816-7","article-title":"Biomineralization mechanisms: A kinetics and interfacial energy approach","volume":"211","author":"Nancollas","year":"2000","journal-title":"J. Cryst. Growth"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"e9130008","DOI":"10.26599\/NTM.2022.9130008","article-title":"Biomimetically precipitated nanocrystalline hydroxyapatite","volume":"1","author":"Wan","year":"2022","journal-title":"Nano TransMed"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"553","DOI":"10.1016\/S1003-6326(07)60132-0","article-title":"In vitro biocompatibility of titanium-nickel alloy with titanium oxide film by H2O2 oxidation","volume":"17","author":"Hu","year":"2007","journal-title":"Trans. Nonferrous Met. Soc. China"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"151755","DOI":"10.1016\/j.apsusc.2021.151755","article-title":"Microstructure and biological properties of titanium dioxide coatings doped with bioactive and bactericidal elements","volume":"575","author":"Ponomarev","year":"2022","journal-title":"Appl. Surf. Sci."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"11214","DOI":"10.1039\/c3ra23252b","article-title":"Enhanced bioactivity and bacteriostasis effect of TiO2 nanofilms with favorable biomimetic architectures on titanium surface","volume":"3","author":"Li","year":"2013","journal-title":"RSC Adv."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Wang, X.X., Hayakawa, S., Tsuru, K., and Osaka, A. (2002). Bioactive titania gel layers formed by chemical treatment of Ti substrate with a H2O2\/HCl solution. Biomaterials, 23.","DOI":"10.1016\/S0142-9612(01)00254-X"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"855","DOI":"10.1023\/A:1008904413859","article-title":"In vivo bone formation by human bone marrow cells: Effect of osteogenic culture supplements and cell densities","volume":"9","author":"Mendes","year":"1998","journal-title":"J. Mater. Sci. Mater. Med."}],"container-title":["Micromachines"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-666X\/15\/7\/886\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T15:10:59Z","timestamp":1760109059000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-666X\/15\/7\/886"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,7,6]]},"references-count":40,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2024,7]]}},"alternative-id":["mi15070886"],"URL":"https:\/\/doi.org\/10.3390\/mi15070886","relation":{},"ISSN":["2072-666X"],"issn-type":[{"value":"2072-666X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,7,6]]}}}