4 research outputs found
Highly Efficient Synthesis of DNA-Binding Polyamides Using a Convergent Fragment-Based Approach
Two advances in the
synthesis of hairpin pyrrole-imidazole polyamides
(PAs) are described. First, the application of a convergent synthetic
strategy is shown, involving the Boc-based solid phase synthesis of
a <i>C</i>-terminal fragment and the solution phase synthesis
of the <i>N</i>-terminal fragment. Second a new hybrid resin
is developed that allows for the preparation of hairpin PAs lacking
a C-terminal β-alanine tail. Both methods are compatible with
a range of coupling reagents and provide a facile, modular route to
prepare PA libraries in high yield and crude purity
Directed Assembly of DNA-Functionalized Gold Nanoparticles Using Pyrrole–Imidazole Polyamides
Traditional methods for the construction of nanoparticle
arrays
and lattices exploit Watson–Crick base pairing of single-stranded
DNA sequences as a proxy for self-assembly. Although this approach
has been utilized in a variety of applications in nanoassembly, diagnostics,
and biomedicine, the diversity of this recognition lexicon could be
considerably increased by developing strategies that recognize the
base-pairing landscape of double-stranded DNA (dsDNA) sequences. Herein
we describe the first report of programmed gold nanoparticle (GNP)
aggregation directed by the recognition of dsDNA sequences using pyrrole–imidazole
polyamide–GNP (PA–GNP) conjugates. We demonstrate the
reversibility and selectivity of this strategy for forming GNP aggregates
in the presence of fully matched dsDNA sequences relative to dsDNA
sequences containing one- and two-base-pair mismatches
Sequence-Selective Detection of Double-Stranded DNA Sequences Using Pyrrole–Imidazole Polyamide Microarrays
We
describe a microarray format that can detect double-stranded
DNA sequences with a high degree of sequence selectivity. Cyclooctyne-derivatized
pyrrole–imidazole polyamides were immobilized on azide-modified
glass substrates using microcontact printing and a strain-promoted
azide–alkyne cycloaddition (SPAAC) reaction. These polyamide-immobilized
substrates selectively detected a seven-base-pair binding site incorporated
within a double-stranded oligodeoxyribonucleotide sequence even in
the presence of an excess of a sequence with a single-base-pair mismatch
Reactive Vapor-Phase Inhibitors for Area-Selective Depositions at Tunable Critical Dimensions
Area-selective depositions (ASD)
take advantage of the chemical
contrast between material surfaces in device fabrication, where a
film can be selectively grown by chemical vapor deposition on metal
versus a dielectric, for instance, and can provide a path to nontraditional
device architectures as well as the potential to improve existing
device fabrication schemes. While ASD can be accessed through a variety
of methods, the incorporation of reactive moieties in inhibitors presents
several advantages, such as increasing thermal stability and limiting
precursor diffusion into the blocking layer. Alkyne-terminated small
molecule inhibitors (SMIs)propargyl, dipropargyl, and tripropargylaminewere
evaluated as metal-selective inhibitors. Modeling these SMIs provided
insight into the binding mechanism, influence of sterics, and complex
polymer network formed from the reaction between inhibitors consisting
of alkene, aromatic, and network branchpoints. While a significant
contrast in the binding of the SMIs on copper versus a dielectric
was observed, residual amounts were detected on the dielectric surfaces,
leading to variable ALD growth rates dependent on pattern-critical
dimensions. This behavior can be controlled and utilized to direct
film growth on patterns only above a critical threshold dimension;
below this threshold, both the dielectric and metal features are protected.
This method provides another design parameter for ASD processes and
may extend its application to broader-ranging device fabrication schemes