DNA-Programmed Modular
Assembly of Cyclic and Linear
Nanoarrays for the Synthesis of Two-Dimensional Conducting Polymers
- Publication date
- Publisher
Abstract
Nanometer-scale arrays of conducting polymers were prepared
on
scaffolds of self-assembling DNA modules. A series of DNA oligomers
was prepared, each containing six 2,5-bis(2-thienyl)pyrrole (SNS)
monomer units linked covalently to N4 atoms of alternating cytosines
placed between leading and trailing 12-nucleobase recognition sequences.
These DNA modules were encoded so the recognition sequences would
uniquely associate through Watson–Crick assembly to form closed-cycle
or linear arrays of aligned SNS monomers. The melting behavior and
electrophoretic migration of these assemblies showed cooperative formation
of multicomponent arrays containing two to five DNA modules (i.e.,
12–30 SNS monomers). The treatment of these arrays with horseradish
peroxidase and H<sub>2</sub>O<sub>2</sub> resulted in oxidative polymerization
of the SNS monomers with concomitant ligation of the DNA modules.
The resulting cyclic and linear arrays exhibited chemical and optical
properties typical of conducting thiophene-like polymers, with a red-end
absorption beyond 1250 nm. AFM images of the cyclic array containing
18 SNS units revealed highly regular 10 nm diameter objects