Journal of Materials Science: Materials in Medicine

, Volume 22, Issue 8, pp 1813–1824

Formation of OTS self-assembled monolayers at chemically treated titanium surfaces



Enhanced biocompatibility of titanium implants highly depends on the possibility of achieving high degrees of surface functionalization for a low immune response and/or enhanced mineralization of bioactive minerals, such as hydroxyapatite. In this respect, surface modification with Self Assembled Monolayers (SAMs) has a great potential in delivering artificial surfaces of improved biocompatibility. Herein, the effectiveness of common chemical pre-treatments, i.e. hydrogen peroxide (H2O2) and Piranha (H2SO4 + H2O2), in facilitating surface decontamination and hydroxylation of titanium surfaces to promote further surface functionalization by SAMs is investigated. The quality of the octadecyltrichlorosilane (OTS) based SAM appeared to strongly depend upon the surface morphology, the density and nature of surface hydroxyl sites resulting from the oxidative pre-treatments. Contrary to common belief, no further hydroxylation of the titanium substrate was observed after the selected chemical pre-treatments, but the number of hydroxyl groups available on the surface was decreased as a result of the formation of a titanium oxide layer with a gel-type structure. Further examinations by atomic force microscopy, infrared spectroscopy and X-ray photoelectron spectroscopy also revealed that mild oxidizing conditions were sufficient to remove surface contamination without detrimental effects on surface hydroxylation state and surface roughness. Furthermore, the adsorption of the alkylsiloxane molecules forming the SAM film is believed to proceed through hydrolysis at surface acidic hydroxyl groups rather than randomly. This site dependent adsorption process has significant implications for further functionalization of titanium based implants. It also highlights the difficulty of achieving an OTS based SAM at the surface of titanium and question the quality of SAMs reported at titanium surfaces so far.


  1. 1.
    Sundgren JE, Bodo P, Lundstrom I. Auger electron spectroscopic studies of the interface between human tissue and implants of titanium and stainless steel. J Colloid Interface Sci. 1986;110:9–20.CrossRefGoogle Scholar
  2. 2.
    Liu Q, Ding J, Mante FK, et al. The role of surface functional groups in calcium phosphate nucleation on titanium foil: a self-assembled monolayer technique. Biomaterials. 2002;23:3103–11.CrossRefGoogle Scholar
  3. 3.
    Liu X, Chu PK, Ding C. Surface modification of titanium, titanium alloys, and related materials for biomedical applications. Mater Sci Eng A. 2004;47:49–121.Google Scholar
  4. 4.
    Furlong RJ, Osborn JF. Fixation of hip prostheses by hydroxyapatite ceramic coatings. J Bone Joint Surg Am. 1991;73B:741–5.Google Scholar
  5. 5.
    Yang Y, Kim KH, Ong JL. A review on calcium phosphate coatings produced using a sputtering process—an alternative to plasma spraying. Biomaterials. 2005;26:327–37.CrossRefGoogle Scholar
  6. 6.
    Campbell AA, Fryxell GE, Linehan JC, et al. Surface-induced mineralization: a new method for producing calcium phosphate coatings. J Biomed Mater Res. 1996;32:111–8.CrossRefGoogle Scholar
  7. 7.
    Majewski PJ, Allidi G. Synthesis of hydroxyapatite on titanium coated with organic self-assembled monolayers. Mater Sci Eng A. 2006;420:13–20.CrossRefGoogle Scholar
  8. 8.
    Mao C, Li H, Cui F, et al. Oriented growth of hydroxyapatite on (0001) textured titanium with functionalized self-assembled silane monolayer as template. J Mater Chem. 1998;8:2795–801.CrossRefGoogle Scholar
  9. 9.
    Masuda Y, Sugiyama T, Koumoto K. Micropatterning of anatase TiO2 thin films from an aqueous solution by a site-selective immersion method. J Mater Chem. 2002;12:2643–7.CrossRefGoogle Scholar
  10. 10.
    Zhu P, Masuda Y, Koumoto K. The effect of surface charge on hydroxyapatite nucleation. Biomaterials. 2004;24:3915–21.CrossRefGoogle Scholar
  11. 11.
    Toworfe GK, Composto RJ, Shapiro IM, et al. Nucleation and growth of calcium phosphate on amine-, carboxyl- and hydroxyl-silane self-assembled monolayers. Biomaterials. 2006;27:631–42.CrossRefGoogle Scholar
  12. 12.
    Zhu P, Masuda Y, Koumoto K. Site-selective adhesion of hydroxyapatite microparticles on charge surfaces in a supersaturated solution. J Colloid Interface Sci. 2001;243:31–6.CrossRefGoogle Scholar
  13. 13.
    Zhu PX, Ishikawa M, Seo WS, et al. Nucleation and growth of hydroxyapatite on an amino organosilane overlayer. J Biomed Mater Res. 2002;59:294–304.CrossRefGoogle Scholar
  14. 14.
    Tanahashi M, Matsuda T. Surface functional group dependence on apatite formation on self-assembled monolayers in a simulated body fluid. J Biomed Mater Res. 1997;34:305–15.CrossRefGoogle Scholar
  15. 15.
    Zhu P, Masuda Y, Yonezawa T, et al. Investigation of apatite deposition onto charged surfaces in aqueous solutions using a quartz-crystal microbalance. J Am Ceram Soc. 2003;86:782–90.CrossRefGoogle Scholar
  16. 16.
    Huang S, Zhou K, Liu Y, et al. Controlled crystallization of hydroxyapatite under hexadecylamine self-assembled monolayer. Trans Nonferr Metal Soc. 2003;13:595–9.Google Scholar
  17. 17.
    Zhu P, Masuda Y, Koumoto K. A novel approach to fabricate hydroxyapatite coating on titanium substrate in an aqueous solution J. Ceram Soc Jpn. 2001;109:676–80.CrossRefGoogle Scholar
  18. 18.
    Nanci A, Wuest JD, Peru L, et al. Chemical modification of titanium surfaces for covalent attachment of biological molecules. J Biomed Mater Res. 1998;40:324–35.CrossRefGoogle Scholar
  19. 19.
    Schreiber F. Structure and growth of self-assembling monolayers. Prog Surf Sci. 2000;65:151–256.CrossRefGoogle Scholar
  20. 20.
    Collins RJ, Sukenik CN. Sulfonate-functionalized, siloxane-anchored, self-assembled monolayers. Langmuir. 1995;11:2322–4.CrossRefGoogle Scholar
  21. 21.
    Lewandowska M, Włodkowska M, Olkowski R, et al. Chemical surface modifications of titanium implants. Macromol Symp. 2007;253:115–21.CrossRefGoogle Scholar
  22. 22.
    Tengvall P, Elwing H, Lundstrom I. Titanium gel made from metallic titanium and hydrogen peroxide. J Colloid Interface Sci. 1989;130:405–13.CrossRefGoogle Scholar
  23. 23.
    Tengvall P, Elwing H, Sjoqvist L, et al. Interaction between hydrogen peroxide and titanium: a possible role in the biocompatibility of titanium. Biomaterials. 1989;10:118–20.CrossRefGoogle Scholar
  24. 24.
    Tengvall P, Lundstrom I, Sjoqvist L, et al. Titanium-hydrogen peroxide interaction: model studies of the influence of the inflammatory response on titanium implants. Biomaterials. 1989;10:166–75.CrossRefGoogle Scholar
  25. 25.
    Wang Y, Lieberman M. Growth of ultrasmooth octadecyltrichlorosilane self-assembled monolayers on SiO2. Langmuir. 2003;19:1159–67.CrossRefGoogle Scholar
  26. 26.
    Ban S, Iwaya Y, Kono H, et al. Surface modification of titanium by etching in concentrated sulfuric acid. Dent Mater. 2006;22:1115–20.CrossRefGoogle Scholar
  27. 27.
    Pan J, Liao H, Leygraf C, et al. Variation of oxide films on titanium induced by osteoblast-like cell culture and the influence of an H2O2 pretreatment. J Biomed Mater Res. 1998;40:244–56.CrossRefGoogle Scholar
  28. 28.
    Hammond JS, Holubka JW, DeVries JE, et al. The application of X-ray photoelectron spectroscopy: a study of interfacial composition-induced paint de-adhesion. Corros Sci. 1981;21:239–53.CrossRefGoogle Scholar
  29. 29.
    Ong JL, Lucas LC, Gregory JC. Electrochemical corrosion analyses and characterization of surface-modified titanium. Appl Surf Sci. 1993;72:7–13.CrossRefGoogle Scholar
  30. 30.
    Pan J, Thierry D, Leygraf C. Hydrogen peroxide toward enhanced oxide growth on titanium in PBS solution: blue coloration and clinical relevance. J Biomed Mater Res. 1996;30:393–402.CrossRefGoogle Scholar
  31. 31.
    Schmidt M. X-ray photoelectron spectroscopy studies on adsorption of amino acids from aqueous solutions onto oxidised titanium surfaces. Arch Orthop Traum Surg. 2001;121:403–10.CrossRefGoogle Scholar
  32. 32.
    Shirkhanzadeh M. XRD and XPS characterization of superplastic TiO2 coatings prepared on Ti6Al4V surgical alloy by an electrochemical method. J Mater Sci Mater Med. 1995;6:206–10.CrossRefGoogle Scholar
  33. 33.
    Kilpadi DV, Raikar GN, Liu J, et al. Effect of surface treatment on unalloyed titanium implants: spectroscopic analyses. J Biomed Mater Res. 1998;40:646–59.CrossRefGoogle Scholar
  34. 34.
    Pouilleau J, Devilliers D, Groult H. Surface study of a titanium-based ceramic electrode material by X-ray photoelectron spectroscopy. J Mater Sci. 1997;32:5645–51.CrossRefGoogle Scholar
  35. 35.
    Takeuchi M, Abe Y, Yoshida Y, et al. Acid pretreatment of titanium implants. Biomaterials. 2003;24:1821–7.CrossRefGoogle Scholar
  36. 36.
    Taborelli M, Jobin M, François P, et al. Influence of surface treatments developed for oral implants on the physical and biological properties of titanium. (I) Surface characterization. Clin Oral Implants Res. 1997;8:208–16.CrossRefGoogle Scholar
  37. 37.
    Feng B, Chen JY, Qi SK, et al. Characterization of surface oxide films on Titanium and bioactivity. J Mater Sci Mater Med. 2002;13:457–64.CrossRefGoogle Scholar
  38. 38.
    Lu G, Bernasek SL, Schwartz J. Oxidation of a polycrystalline titanium surface by oxygen and water. Surf Sci. 2000;458:80–90.CrossRefGoogle Scholar
  39. 39.
    Brunnette DM, Tengvall P, Textor M, et al. Titanium in medicine. Materials science, surface science, engineering, biological responses and medical applications. Heidelberg: Springer; 2001.Google Scholar
  40. 40.
    Feng B, Chen JY, Qi SK, et al. Carbonate apatite coating on titanium induced rapidly by precalcification. Biomaterials. 2002;23:173–9.CrossRefGoogle Scholar
  41. 41.
    Sham TK, Lazarus MS. X-ray photoelectron spectroscopy (XPS) studies of clean and hydrated TiO2 (Rutile) surfaces. Chem Phys Lett. 1979;68:426–32.CrossRefGoogle Scholar
  42. 42.
    Boehm HP. Acidic and basic properties of hydroxylated metal oxide surfaces. Faraday Discuss. 1971;52:264–75.CrossRefGoogle Scholar
  43. 43.
    Matsumura K, Hyon S, Nakajima N, et al. Adhesion between poly(ethylene-co-vinyl alcohol) (EVA) and titanium. J Biomed Mater Res. 2002;60:309–15.CrossRefGoogle Scholar
  44. 44.
    Blesa MA, Weisz AD, Morando PJ, et al. The interaction of metal oxide surfaces with complexing agents dissolved in water. Coord Chem Rev. 2000;196:31–6.CrossRefGoogle Scholar
  45. 45.
    Tamura H, Mita K, Tanaka A, et al. Mechanism of hydroxylation of metal oxide surfaces. J Colloid Interface Sci. 2001;243:202–7.CrossRefGoogle Scholar
  46. 46.
    Wang LQ, Baer DR, Engelhard MH, et al. The adsorption of liquid and vapor water on TiO2 (110) surfaces: the role of defects. Surf Sci. 1995;344:237–50.CrossRefGoogle Scholar
  47. 47.
    Kulkarni SA, Mirji SA, Mandale AB, et al. Growth kinetics and thermodynamic stability of octadecyltrichlorosilane self-assembled monolayer on Si(100) substrate. Mater Lett. 2005;59:3890–5.CrossRefGoogle Scholar
  48. 48.
    Ulman A. Formation and structure of self-assembled monolayers. Chem Rev. 1996;96:1533–54.CrossRefGoogle Scholar
  49. 49.
    Abdelghani A, Hleli S, Cherif K. Optical and electrochemical characterization of self-assembled octadecyltrichlorosilane monolayer on modified silicon electrode. Mater Lett. 2002;56:1064–8.CrossRefGoogle Scholar
  50. 50.
    Collet J, Vuillaume D. Nano-field effect transistor with an organic self-assembled monolayer as gate insulator. Appl Phys Lett. 1998;73:2681–3.CrossRefGoogle Scholar
  51. 51.
    Hoffmann H, Mayer U, Krischanitz A. Structure of alkylsiloxane monolayers on silicon surfaces investigated by external reflection infrared spectroscopy. Langmuir. 1995;11:1304–12.CrossRefGoogle Scholar
  52. 52.
    Mirji SA. Adsorption of octadecyltrichlorosilane on Si(100)/SiO2 and SBA-15. Colloids Surf A. 2006;289:133–40.CrossRefGoogle Scholar
  53. 53.
    Yasseri AA, Sharma S, Kamins TI. Alkylsiloxane self-assembled monolayer formation guided by nanoimprinted Si and SiO2 templates. Appl Phys Lett. 2006;89:10–153121.CrossRefGoogle Scholar
  54. 54.
    Fadeev AY, McCarthy TJ. Self-assembly is not the only reaction possible between alkyltrichlorosilanes and surfaces: monomolecular and oligomeric covalently attached layers of dichloro- and trichloroalkylsilanes on silicon. Langmuir. 2000;16:7268–74.CrossRefGoogle Scholar
  55. 55.
    Khatri OP, Biswas SK. Boundary lubrication capabilities of alkylsilane monolayer self-assembled on aluminium as investigated using FTIR spectroscopy and nanotribometry. Surf Sci. 2006;600:4399–404.CrossRefGoogle Scholar
  56. 56.
    Parikh AN, Allara DL. An intrinsic relationship between molecular structure in self-assembled n-alkylsiloxane monolayers and deposition temperature. J Phys Chem B. 1994;98:7577–90.CrossRefGoogle Scholar
  57. 57.
    Rye RR, Nelson GC, Dugger MT. Mechanistic aspects of alkylchlorosilane coupling reactions. Langmuir. 1997;13:2965–72.CrossRefGoogle Scholar
  58. 58.
    Boujday S, Lambert JF, Che M. Bridging the gap between solution and solid-state chemistry molecular recognition at the liquid–solid interface. Top Catal. 2003;24:37–42.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  1. 1.School of Engineering and Materials Science, Queen MaryUniversity of LondonLondonUK
  2. 2.School of Chemical EngineeringThe University of New South WalesSydneyAustralia

Personalised recommendations