We demonstrate the fabrication of sub-100-nm DNA surface patterns by scanning near-field optical lithography using a near-field scanning optical microscope coupled to a UV laser and a chloromethylphenylsiloxane (CMPS) self-assembled monolayer (SAM). The process involves 244-nm exposure of the CMPS SAM to create nanoscale patterns of surface carboxylic acid functional groups, followed by their conversion to the N-hydroxysuccinimidyl ester and reaction of the active ester with DNA to spatially control DNA grafting with high selectivity.
The deep ultraviolet (λ < ∼250 nm) photochemistry of
chemisorbed organosilane self-assembled films
of the type R(CH2)
n
SiO−surface
where n = 0, 1, 2 and R = phenyl, naphthyl, or
anthracenyl is explored.
Photochemistry is examined using 193 and 248 nm laser irradiation
as well as deep ultraviolet lamp
sources. It is demonstrated for a variety of systems, including
single and multiple rings as well as
heterocycles, that the primary photochemical mechanism is cleavage of
the Si−C bond. Photocleavage
of the organic group generates a polar, wettable silanol surface that
is amenable to subsequent remodification
by organosilane chemisorption, allowing the fabrication of
high-resolution patterns of chemical functional
groups in a single molecular plane. The use of patterned
monolayers as templates of reactivity for subsequent
selective chemical reactions is demonstrated.
We describe a new method for depositing patterned materials, based on non‐covalent trapping of ligands in solvent‐templated nanocavities created in aromatic, self‐assembled monolayer or polymer films. A model has been developed and tested to describe nanocavity formation and the ligand adsorption process, which occurs via ligand exclusion from ambient, aqueous solution into the hydrophobic nanocavities. Ligand adsorption rates and ligand adsorbate reactivity with solution species are governed by ligand size/geometry design factors identified using the model. Spatial control of adsorption is achieved via film photochemical changes that inhibit subsequent ligand adsorption/accessibility (UV or X‐ray) or displacement of entrapped ligands (50 keV electron‐beam) during film patterning. The reactivity of the adsorbed ligand is illustrated by the selective binding of PdII species that catalyze electroless metal deposition. Fabrication of high‐resolution (≈ 50 nm), positive‐tone patterns in nickel with acceptable feature‐edge acuity and critical dimension control (≈ 5 %) is demonstrated.
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