Nanostructures of functionalized gold nanoparticles prepared by particle lithography with organosilanes

Periodic arrays of organosilane nanostructures were prepared with particle lithography to define sites for selective adsorption of functionalized gold nanoparticles. Essentially, the approach for nanoparticle lithography consists of procedures with two masks. First, latex mesospheres were used as a surface mask for deposition of an organosilane vapor, to produce an array of holes within a covalently bonded, organic thin film. The latex particles were readily removed with solvent rinses to expose discrete patterns of nanosized holes of uncovered substrate. The nanostructured film of organosilanes was then used as a surface mask for a second patterning step, with immersion in a solution of functionalized nanoparticles. Patterned substrates were fully submerged in a solution of surface-active gold nanoparticles coated with 3- mercaptopropyltrimethoxysilane. Regularly shaped, nanoscopic areas of bare substrate produced by removal of the latex mask provided sites to bind silanol-terminated gold nanoparticles, and the methyl-terminated areas of the organosilane film served as an effective resist, preventing nonspecific adsorption on masked areas. Characterizations with atomic force microscopy demonstrate the steps for lithography with organosilanes and functionalized nanoparticles. Patterning was accomplished for both silicon and glass substrates, to generate nanostructures with periodicities of 200-300 nm that match the diameters of the latex mesospheres of the surface masks. Nanoparticles were shown to bind selectively to uncovered, exposed areas of the substrate and did not attach to the methyl-terminal groups of the organosilane mask. Billions of well-defined nanostructures of nanoparticles can be generated using this high-throughput approach of particle lithography, with exquisite control of surface density and periodicity at the nanoscale.