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Coating method for functionalization and nanofabrication of diamond
Langmuir Published online (November 26)
Shimamoto Laboratory, Molecular Biomechanism Laboratory

Aminosilane Multilayer Formed on a Single-Crystalline Diamond Surface with Controlled Nanoscopic Hardness and Bioactivity by a Wet Process
Yosuke Amemiya, Akiko Hatakeyama and Nobuo Shimamoto
Langmuir Published online at http://pubs.acs.org/doi/abs/10.1021/la801556x (November 26)

   Diamond is a promising material for a nanoneedle with a diameter of 10-200 nm which can be used for delivering substance and sampling intra- and inter cellular substance because of its high stiffness and chemical stability. However, due to the stability, fuctinalization of diamond surface is difficult. Here we succeeded in forming stable aminosilane multilayer on oxygen-terminated diamond surface by combining common wet methods. Interestingly, hardness of the formed layer depended on the dielectric constant of the solvent used for deposition of silane. Control of hardness of the silane layer allowed us to nanofabricate diamond surface with an AFM. The dielectric constant of the solvent also determined the density of reactive surface amino residues which is incompatible with hardness. High density of reactive amino residue and hardness were reconciled by a multi-step deposition in different solvents. We proposed a mechanism for the formation of silane layer with controlled hardness on a diamond surface.
(Japan Patent, publication number: 2008-169080)


Nanofabrication of diamond surface. Square holes (1.0 um2) were formed by AFM scratching. A: schematic illustration of AFM scratching, B: applied forces, C: aminosilane layer formed in ethanol (soft layer), D: aminosilane layer formed in chloroform (hard layer).