Orthogonal Chemical Functionalization of Au/SiO₂/TiW Patterned Substrates

Macropatterned and micropatterned gold/silicon dioxide/titanium tungsten (Au/SiO₂/TiW) substrates were orthogonally functionalized: three different molecules (monovalent silane, thiol, and phosphonic acid) were used to specifically form organolayers on Au, SiO₂, or TiW areas of patterned substrates. The orthogonality of the functionalization (i.e., selective grafting of thiol on Au, phosphonic acid on TiW, and silane on SiO₂) was assessed by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), Fourier transform infrared spectroscopy (FTIR), and contact angle measurements. These results are especially promising for the selective anchoring of targets (e.g., biomolecules, nanoparticles, nanowires, nanotubes, or other nano-objects) onto patterned zones of multimaterial substrates, such as nanosensors or other nanodevices.