{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T05:10:36Z","timestamp":1760073036375,"version":"build-2065373602"},"reference-count":53,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2025,10,8]],"date-time":"2025-10-08T00:00:00Z","timestamp":1759881600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Ministry of Science and Technology, Taiwan","award":["MOST 107-2221-E-150-005"],"award-info":[{"award-number":["MOST 107-2221-E-150-005"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>The aim of present study is to deposit protective coatings with various surface chemical states on AZ91D Mg alloy. Hydrothermal bioactive ceramic coatings are performed with a surface modification by the chemical bonding of self-assembled monolayers (SAM). The electrochemical corrosion behaviors of various surface-coated AZ91D alloy within DMEM cell culture medium related to their surface chemical states are evaluated through microstructure observations, XPS surface chemical bonding analysis, static contact angles measurements, potentiodynamic polarization curves, and immersion tests. XRD and high resolution XPS of F 1s analysis results show that the hydrothermal FHA coating with a phase composition of Ca10(PO4)6(OH)F can be effectively and uniformly deposited on the AZ91D alloy. FHA-coated AZ91D displays better anti-corrosion performances and lower degradation rates than those of uncoated AZ91D alloy in the DMEM solution. Through the high resolution XPS analysis of O 1s and P 2p spectra, it is demonstrated that 1-butylphosphonic acid (BP), 1 octylphosphonic acid (OP), and dodecylphosphonic acid (DP) molecules can be effectively bonded on the FHA surface by a covalent bond to form SAM. BP\/OP\/DP-SAM specimens display increased static contact angles to show a hydrophobic surface. It demonstrates that the SAM surface treatment can further enhance the corrosion resistance of FHA-coated AZ91D in the DMEM solution. After 2\u201316 days in vitro immersion tests in the DMEM, the surface SAM-bonded hydrophobic BP\/OP\/DP-SAM layers can effectively inhibit and reduce the penetration of DMEM into FHA coating. Long alkyl chains of the dodecylphosphonic acid (DP) SAM represents superior enhancing effects on the reduction of corrosion properties and weight loss.<\/jats:p>","DOI":"10.3390\/ma18194633","type":"journal-article","created":{"date-parts":[[2025,10,8]],"date-time":"2025-10-08T14:06:53Z","timestamp":1759932413000},"page":"4633","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Self-Assembled Monolayers of Various Alkyl-Phosphonic Acids on Bioactive FHA Coating for Improving Surface Stability and Corrosion Resistance of Biodegradable AZ91D Mg Alloy"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7497-0152","authenticated-orcid":false,"given":"Chung-Wei","family":"Yang","sequence":"first","affiliation":[{"name":"Department of Materials Science and Engineering, National Formosa University, No. 64, Wunhua Road, Huwei, Yunlin 632301, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Peng-Hsiu","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Materials Science and Engineering, National Formosa University, No. 64, Wunhua Road, Huwei, Yunlin 632301, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,10,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1680","DOI":"10.1016\/j.actbio.2010.02.028","article-title":"The history of biodegradable magnesium implants: A review","volume":"6","author":"Witte","year":"2010","journal-title":"Acta Biomater."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1007\/s10853-012-6572-2","article-title":"Biodegradable magnesium implants for orthopedic applications","volume":"48","author":"Waizy","year":"2013","journal-title":"J. Mater. Sci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"3025","DOI":"10.1016\/j.jma.2024.05.028","article-title":"Magnesium-based biomaterials for coordinated tissue repair: A comprehensive overview of design strategies, advantages, and challenges","volume":"12","author":"Chen","year":"2024","journal-title":"J. Magnes. Alloys"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"25","DOI":"10.4028\/www.scientific.net\/JBBTE.12.25","article-title":"Biodegradable magnesium alloys: A review of material development and applications","volume":"12","author":"McGoron","year":"2012","journal-title":"J. Biomim. Biomater. Tissue Eng."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"356","DOI":"10.1016\/j.jma.2021.08.017","article-title":"Magnesium based implants for functional bone tissue regeneration\u2014A review","volume":"10","author":"Uppal","year":"2022","journal-title":"J. Magnes. Alloys"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"4396","DOI":"10.1016\/j.jmrt.2023.02.037","article-title":"Review on magnesium and magnesium-based alloys as biomaterials for bone immobilization","volume":"23","author":"He","year":"2023","journal-title":"J. Mater. Res. Technol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"948","DOI":"10.1016\/j.jma.2025.01.025","article-title":"Advances in magnesium-based bioresorbable cardiovascular stents: Surface engineering and clinical prospects","volume":"13","author":"Kumar","year":"2025","journal-title":"J. Magnes. Alloys"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Zhang, N., Zhang, Q., Shao, H., Shan, Z., Xu, J., Tong, W., Wong, R.M.Y., and Qin, L. (2025). Magnesium as an emerging bioactive material for orthopedic applications: Beside needs lead the way from innovation to clinical translation. Regen. Biomater., 12.","DOI":"10.1093\/rb\/rbaf032"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2737","DOI":"10.1016\/S0010-938X(02)00075-6","article-title":"Corrosion behaviour of high pressure die-cast and semi-solid cast AZ91D alloys","volume":"44","author":"Mathieu","year":"2002","journal-title":"Corro. Sci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1912","DOI":"10.1039\/C3TB21746A","article-title":"Effect of alloying elements on the corrosion behavior and biocompatibility of degradable magnesium alloys: A review","volume":"2","author":"Ding","year":"2014","journal-title":"J. Mater. Chem. B"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"948","DOI":"10.1016\/j.msec.2016.06.020","article-title":"Biodegradable magnesium alloys for orthopaedic applications: A review on corrosion, biocompatibility and surface modifications","volume":"68","author":"Agarwal","year":"2016","journal-title":"Mater. Sci. Eng. C"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"12158","DOI":"10.1007\/s10853-023-08782-z","article-title":"A review of magnesium corrosion in bio-applications: Mechanism, classfication, modeling, in-vitro, and in vivo experimental testing, and tailoring Mg corrosion rate","volume":"58","author":"Zhao","year":"2023","journal-title":"J. Mater. Sci."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"471","DOI":"10.1016\/j.actbio.2024.08.015","article-title":"Bone cells influence the degradation interface of pure Mg and WE43 materials: Insights from multimodal in vitro analysis","volume":"187","author":"Martinez","year":"2024","journal-title":"Acta Biomater."},{"key":"ref_14","first-page":"363","article-title":"Reduction reactions dominate the interactions between Mg alloys and cells: Understanding the mechanisms","volume":"45","author":"Kim","year":"2025","journal-title":"Bioact. Mater."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"340","DOI":"10.1002\/jcb.240560310","article-title":"Underlying mechanisms at the bone-biomaterial interface","volume":"56","author":"Schwartz","year":"1994","journal-title":"J. Cell. Biochem."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1016\/j.jma.2019.09.008","article-title":"Advances in coatings on biodegradable magnesium alloys","volume":"8","author":"Yin","year":"2020","journal-title":"J. Magnes. Alloys"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Guo, X., Hu, Y., Yuan, K., and Qiao, Y. (2022). Review of the effect of surface coating modification on magnesium alloy biocompatibility. Materials, 15.","DOI":"10.3390\/ma15093291"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"293","DOI":"10.1002\/jbm.a.33267","article-title":"In vitro and in vivo evaluations on osteogenesis and biodegradability of a \u03b2-tricalcium phosphate coated magnesium alloy","volume":"100","author":"Chai","year":"2012","journal-title":"J. Biomed. Mater. Res. A"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Li, M., He, P., Wu, Y., Zhang, Y., Xia, H., Zheng, Y., and Han, Y. (2016). Stimulatory effects of the degradation products from Mg-Ca-Sr alloy on the osteogenesis through regulating ERK signaling pathway. Sci. Rep., 6.","DOI":"10.1038\/srep32323"},{"key":"ref_20","first-page":"3819","article-title":"Surface protective coatings on Mg alloys\u2014A review","volume":"47","author":"Chandra","year":"2021","journal-title":"J. Matpr."},{"key":"ref_21","first-page":"1842","article-title":"Anti-corrosive coatings of magnesium: A review","volume":"48","author":"Johari","year":"2022","journal-title":"J. Matpr."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"118","DOI":"10.1016\/j.corsci.2013.03.017","article-title":"Formation of dicalcium phosphate dihydrate on magnesium alloy by micro-arc oxidation coupled with hydrothermal treatment","volume":"72","author":"Chang","year":"2013","journal-title":"Corros. Sci."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"126318","DOI":"10.1016\/j.surfcoat.2020.126318","article-title":"Enhanced corrosion resistance and biocompatibility of biodegradable magnesium alloy modified by calcium phosphate\/collagen coating","volume":"401","author":"Guo","year":"2020","journal-title":"Surf. Coat. Technol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"106653","DOI":"10.1016\/j.porgcoat.2021.106653","article-title":"Improving the corrosion resistance and biocompatibility of magnesium alloy via composite coatings of calcium phosphate\/carbonate induced by silane","volume":"163","author":"Wang","year":"2022","journal-title":"Prog. Org. Coat."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Drevet, R., Faure, J., and Benhayoune, H. (2023). Bioactive calcium phosphate coatings for bone implant applications: A review. Coatings, 13.","DOI":"10.20944\/preprints202305.0832.v1"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"3238","DOI":"10.1016\/j.jmrt.2024.07.046","article-title":"Recent advances in protective coatings and surface modifications for corrosion protection of Mg alloys","volume":"31","author":"Yao","year":"2024","journal-title":"J. Mater. Res. Technol."},{"key":"ref_27","first-page":"1223","article-title":"Calcium phosphate coatings enhance biocompatibility and degradation resistance of magnesium alloy: Correlating in vitro and in vivo studies","volume":"6","author":"Gao","year":"2021","journal-title":"Bioact. Mater."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"7","DOI":"10.1016\/j.cej.2018.01.083","article-title":"Biomimetic fluoridated hydroxyapatite coating with micro\/nano-topography on magnesium alloy for orthopaedic application","volume":"339","author":"Shen","year":"2018","journal-title":"Chem. Eng. J."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"443","DOI":"10.1016\/j.microc.2018.10.007","article-title":"Co-doped hydroxyapatites as potential materials for biomedical applications","volume":"144","author":"Yilmaz","year":"2019","journal-title":"Microchem. J."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Kubiak-Mihkelsoo, Z., Kostrzebska, A., Blaszczyszyn, A., Pitulaj, A., Dominiak, M., Gedrange, T., Nawrot-Hadzik, I., Matys, J., and Hadzik, J. (2025). Ionic doping of hydroxyapatite for bone regeneration: Advances in structure and properties over two decades\u2014A narrative review. Appl. Sci., 15.","DOI":"10.3390\/app15031108"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Razavi, M., Fathi, M., Savabi, O., Tayebi, L., and Vashaee, D. (2020). Biodegradable magnesium bone implants coated with a novel bioceramic nanocomposite. Materials, 13.","DOI":"10.3390\/ma13061315"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"5207","DOI":"10.1021\/acs.iecr.5b04583","article-title":"Evaluation of microstructural features and in vitro biocompatibility of hydrothermally coated fluorohydroxyapatite on AZ80 Mg alloy","volume":"55","author":"Wang","year":"2016","journal-title":"Ind. Eng. Chem. Res."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Wang, S.H., Lee, S.P., Yang, C.W., and Lo, C.M. (2021). Surface modification of biodegradable Mg-based scaffolds for human mesenchymal stem cell proliferation and osteogenic differentiation. Materials, 14.","DOI":"10.3390\/ma14020441"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"26","DOI":"10.1002\/term.131","article-title":"Effect of functional end groups of silane self assembled monolayer surfaces on apatite formation, fibronectin adsorption and osteoblast cell function","volume":"3","author":"Toworfe","year":"2009","journal-title":"J. Tissue Eng. Regen. Med."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"3242","DOI":"10.1016\/j.actbio.2010.02.032","article-title":"Stability of antibacterial self-assembled monolayers on hydroxyapatite","volume":"6","author":"Torres","year":"2010","journal-title":"Acta Biomater."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"524","DOI":"10.1002\/jbm.a.32714","article-title":"Effects of surface chemistry prepared by self-assembled monolayers on osteoblast behavior","volume":"94","author":"Nakaoka","year":"2010","journal-title":"J. Biomed. Mater. Res. A"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"196","DOI":"10.1166\/jbt.2013.1084","article-title":"Nanolayers on magnesium (Mg) alloy for metallic bone tissue engineering scaffolds","volume":"3","author":"Mahapatro","year":"2013","journal-title":"J. Biomater. Tissue Eng."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1016\/j.msec.2015.05.018","article-title":"Bio-functional nano-coatings on metallic biomaterials","volume":"55","author":"Mahapatro","year":"2015","journal-title":"Mater. Sci. Eng. C"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1848","DOI":"10.1021\/ja02254a006","article-title":"The constitution and fundamental properties of solids and liquids. II. Liquids","volume":"39","author":"Langmuir","year":"1917","journal-title":"J. Am. Chem. Soc."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"16074","DOI":"10.1021\/ja035956z","article-title":"Bonding self-assembled, compact organophosphonate monolayers to the native oxide surface of silicon","volume":"125","author":"Hanson","year":"2003","journal-title":"J. Am. Chem. Soc."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"280","DOI":"10.1016\/j.jcis.2011.04.039","article-title":"Liquid phase formation of alkyl- and perfluoro-phosphonic acid derived monolayers on magnesium alloy AZ31 and their chemical properties","volume":"360","author":"Ishizaki","year":"2011","journal-title":"J. Colloid. Interf. Sci."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"6009","DOI":"10.1021\/la200122x","article-title":"Corrosion resistant performances of alkanoic and phosphonic acids derived self-assembled monolayers on magnesium alloy AZ31 by vapor-phase method","volume":"27","author":"Ishizaki","year":"2011","journal-title":"Langmuir"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1146\/annurev.bb.25.060196.000415","article-title":"Using self-assembled monolayers to understand the interactions of man-made surfaces with proteins and cells","volume":"25","author":"Mrksich","year":"1996","journal-title":"Annu. Rev. Biophys. Biomol. Struct."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"3074","DOI":"10.1016\/j.biomaterials.2007.03.013","article-title":"Effect of wettability and surface functional groups on protein adsorption and cell adhesion using well-defined mixed self-assembled monolayers","volume":"28","author":"Arima","year":"2007","journal-title":"Biomaterials"},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Yang, C.W., Liu, C., Lin, D.J., Yeh, M.L., and Lee, T.M. (2017). Hydrothermal treatment and butylphosphonic acid derived self-assembled monolayres for improving the surface chemistry and corrosion resistance of AZ61 magnesium alloy. Sci. Rep., 7.","DOI":"10.1038\/s41598-017-17199-z"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"715","DOI":"10.1016\/j.actbio.2009.10.031","article-title":"Nanosized and nanocrystalline calcium orthophosphates","volume":"6","author":"Dorozhkin","year":"2010","journal-title":"Acta Biomater."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"116956","DOI":"10.1016\/j.bone.2023.116956","article-title":"Nano-hydroxyapatite structures for bone regenerative medicine: Cell-material interaction","volume":"179","author":"Hoveidaei","year":"2024","journal-title":"Bone"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"357","DOI":"10.1002\/anie.200352565","article-title":"Reversible switching between superhydrophilicity and superhydrophobicity","volume":"43","author":"Sun","year":"2004","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"102016","DOI":"10.1016\/j.nano.2019.102016","article-title":"Hydrothermal treatment of etched titanium: A potential surface nano-modification technique for enhanced biocompatibility","volume":"20","author":"Vishnu","year":"2019","journal-title":"Nanomed. NBM"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"2728","DOI":"10.1016\/j.actbio.2009.03.014","article-title":"Kinetics of hydrothermal crystallization under saturated steam pressure and the self-healing effect by nanocrystallite for hydroxyapatite coatings","volume":"5","author":"Yang","year":"2009","journal-title":"Acta Biomater."},{"key":"ref_51","doi-asserted-by":"crossref","unstructured":"Yang, C.W., and Wang, G.K. (2020). Effect of hydrothermal (Sr)-hydroxyapatite coatings on the corrosion resistance and Mg2+ ion release to enhance osteoblastic cell responses of AZ91D alloy. Materials, 13.","DOI":"10.3390\/ma13030591"},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"6897","DOI":"10.1016\/j.electacta.2010.05.070","article-title":"Fabrication of hydrophobic surface with hierarchical structure on Mg alloy and its corrosion resistance","volume":"55","author":"Wang","year":"2010","journal-title":"Electrochim. Acta"},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"20","DOI":"10.1016\/j.apsusc.2018.04.235","article-title":"Biofunctionization of biodegradable magnesium alloy to improve the in vitro corrosion resistance and biocompatibility","volume":"451","author":"Zhang","year":"2018","journal-title":"Appl. Surf. Sci."}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/18\/19\/4633\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T04:41:24Z","timestamp":1760071284000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/18\/19\/4633"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,10,8]]},"references-count":53,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2025,10]]}},"alternative-id":["ma18194633"],"URL":"https:\/\/doi.org\/10.3390\/ma18194633","relation":{},"ISSN":["1996-1944"],"issn-type":[{"type":"electronic","value":"1996-1944"}],"subject":[],"published":{"date-parts":[[2025,10,8]]}}}