Chemistry Reference
In-Depth Information
Figure 4.6 Phosphoramidite coupling onto hydroxyl-functionalized ROMP polymers
(Watson et al. 2001).
weight polymers. The radius of gyration (R
g
) of the associated structures scaled with
M
w
0.7
, indicating rodlike behavior typical of DNA. The introduction of flexible PEG
spacers between the self-complementary 8-base sequences led to cyclic formation
and slow reorganization into linear, high molecular weight species.
Watson et al. (2001) synthesized ROMP homopolymers and block copolymers
from hydroxyl containing norbornene monomers (Fig. 4.6). The hydroxyl functional
groups were phosphoramidated and attached to DNA oligonucleotides.
Complementary DNA oligonucleotides containing ROMP polymers were mixed in
solution and resulted in precipitation of the hydrogen bonded complex. Heating of
this complex produced a melting point similar to that observed in pure DNA oligo-
nucleotides near 75 8C. Gold nanoparticles containing DNA strands were complexed
with complementary difunctional polymeric oligonucleotides, resulting in aggrega-
tion of the gold nanoparticles into a network structure as observed with TEM and
surface plasmon resonance.
Peptide nucleic acids (PNAs) are a class of polymers with peptide or
pseudopeptide backbones and pendant nucleotide bases. PNAs typically lack the
helicity of DNA but benefit from stronger association and solubility in organic
Figure 4.7 Synthesis of PNA-functionalized crosslinker molecule and association of a comp-
lementary PNA-terminated polymer synthesized by ATRP (Wang et al. 2005).
