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Parameters controlling octadecyl phosphonic acid self-assembled monolayers on titanium dioxide for anti-fouling biomedical applications

Liana Azizova, David Morgan, Jeff Rowlands, Emmanuel Brousseau, Tetiana Kulik, Borys Palianytsia, Jason Peter Mansell, James Birchall, Thomas Wilkinson Orcid Logo, Alastair Sloan, Wayne Nishio Ayre

Applied Surface Science, Volume: 604, Start page: 154462

Swansea University Author: Thomas Wilkinson Orcid Logo

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Abstract

Octadecylphosphonic acid (ODPA) self-assembled monolayers (SAMs) have demonstrated potential for deterring bacterial attachment to titanium, however the coating process is time consuming and uses toxic solvents. In this study, ODPA SAM quantity, quality, and structure were evaluated on titanium quar...

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Published in: Applied Surface Science
ISSN: 0169-4332
Published: Elsevier BV 2022
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa61765
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Abstract: Octadecylphosphonic acid (ODPA) self-assembled monolayers (SAMs) have demonstrated potential for deterring bacterial attachment to titanium, however the coating process is time consuming and uses toxic solvents. In this study, ODPA SAM quantity, quality, and structure were evaluated on titanium quartz crystal microbalance (QCM) sensors by varying solvent type (anisole or cyclopentyl methyl ether (CPME), environmentally friendly non-polar solvents); ODPA concentration (0.5 mM or 1 mM); and temperature (21 °C or 60 °C). Surfaces were characterised using QCM frequency and dissipation measurements and Sauerbrey mass calculations; X-ray photoelectron spectroscopy; water contact angle measurements; and temperature-programmed desorption mass spectrometry (TPD-MS). Anti-fouling ability was established against Staphylococcus aureus. Incubation in 0.5 mM ODPA in CPME at 21 °C rapidly formed uniform rigid ODPA SAMs as demonstrated by high Sauerbrey mass (≈285-290 ng/cm2), viscoelastic modelling, high atomic percentage surface phosphorus (1.1 %) and high water contact angles (117.6 ± 2.5°), consistent across the entire sample surface. High temperatures or the use of anisole resulted in suspected multilayer formation, which reduced bacterial attachment. TPD-MS confirmed covalent bonding of ODPA SAMs on TiO2 at ≈ 110–120 °C and thermal stability below 300 °C. This study demonstrates the key parameters that control ODPA SAM formation on titanium and their future potential for biomedical applications.
Keywords: Octadecylphosphonic acid (ODPA); Self-assembled monolayers (SAMs); Titanium; Quartz crystal microbalance (QCM); Atomic force microscopy (AFM); X-ray photoelectron spectroscopy (XPS); Water contact angle; Temperature-programmed mass spectrometry (TPD-MS); Mono- and bidentate attachment
College: Faculty of Medicine, Health and Life Sciences
Funders: This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) grant number EP/T016124/1. XPS data collection was performed at the EPSRC National Facility for XPS (‘HarwellXPS’), operated by Cardiff University and UCL, under contract No. PR16195. We would also like to thank the Armed Forces of Ukraine for providing security to perform this work. For the purpose of open access, the author has applied a CC BY public copyright licence (‘CC BY-ND public copyright licence’) to any Author Accepted Manuscript version arising.
Start Page: 154462