Patterning the molecular printboard: Patterning cyclodextrin monolayers on silicon oxide using nanoimprint lithography and its application in 3D multilayer nanostructuring

An accurate and versatile process for the fabrication of high-resolution 3D nanostructures combining top-down and bottom-up nanofabrication schemes is described here. The method is based on layer-by-layer (LBL) assembly of functionalized nanoparticles (NPs) bound together by means of supramolecular interactions between a layer of adamantyl-functionalized dendrimers, the guest, and cyclodextrin (CD)-functionalized nanoparticles, the host. First, a self-assembled CD monolayer (CD SAM) was patterned using nanoimprint lithography (NIL) and later used to anchor supramolecular LBL assemblies onto it. The versatility of the process was demonstrated by using NPs of different size and nature. Two types of LBL assemblies were fabricated based on (i) 2.8nm CD-functionalized Au NPs, which allow an accurate height control and (ii) 60nm CD-functionalized SiO₂ particles, which permit the fabrication of nanostructures. In one of the cases vertical deposition was used to obtain high particle ordering. Both types of NP were used to produce nanostructured LBL assemblies with lateral sizes below 100nm. Physical confinement was observed when using 60nm CD-functionalized SiO₂ particles in the sub-300nm scale on the first and second bilayers. Finally, periodic patterns of single nanoparticles were achieved.