Figure 1.

Schematic diagram showing the different approaches examined in this work. (a) A commercial cantilever SNOM probe, coated on its front face with titania, is illuminated from the back face by light from an HeCd laser. (b) Alternatively, a beam of light from an HeCd laser is directed onto the apex of a titania-coated AFM probe held in close proximity to a SAM. (c) Local exposure of a SAM of alkylthiolates leads to their degradation and enables their replacement by a second, contrasting thiolate in a solution-phase process. (d) Degradation of OEG-terminated silanes yields aldehyde functional groups, which bind nitrilotriacetic acid via an amine linker. Complexation of the surface with Ni²⁺ enables site-specific binding of His-tagged green fluorescent protein (GFP).