Self-Assembled Monolayers of Bisphosphonates: Influence of Side Chain

INSERM U646, “Ingenierie de la Vectorisation Particulaire”, 10 rue A. Boquel, F-49100 Angers, FranceReceived December 1, 2008. Revised Manuscript Received May 13, 2009Bisphosphonates form self-assembled monolayers (SAMs) spontaneously on stainless steel, silicon, and titaniumoxidized surfaces. We used contact angle measurements, atomic force microscopy, and X-ray reflectivity analysis tostudy the formation of SAMs on a model surface of ultraflat titanium (rms=0.2 nm). The results were extended tostandard materials (mechanically polished titanium, stainless steel, and silicon) and showed that water-solublebisphosphonic perfluoropolyether can easily form SAMs, with 100% surface coverage and a layer thickness of lessthan 3 nm. Hydrophobic (water contact angle >110 on stainless steel or titanium) and lipophobic (methylene iodidecontact angle >105 on titanium) properties are discussed in terms of industrial applications.