Chemistry Reference
In-Depth Information
Figure 4.5 Scheme for stepwise synthesis of oligonucleotides via coupling of phosphorami-
dite-functionalized nucleosides. Reprinted from Noro et al. (2005). Copyright 2005 American
Chemical Society.
repetition of the chemistry to generate multiple thymidine residues. Noro et al. (2005)
synthesized anionic deuterated polystyrenes with five terminal thymidine units that
formed a cylindrical morphology. Microphase separation was also visible for a
single terminal thymidine unit; however, the exact morphological structure was not
determined.
Xu and colleagues (2004) synthesized DNA oligonucleotides consisting of 8-base
self-complementary sequences repeated twice in the same molecule to engender
ditopic linear self-assembly. The association of these molecules resulted in a
degree of polymerization of roughly 10, corresponding to a molecular weight of
182 000 g/mol at a 0.54 mM concentration in water. Injections of varying volumes
of the associated polymer onto a size exclusion chromatograph resulted in decreasing
apparent molecular weight for smaller injection volumes, which was consistent
with dilution leading to a lower effective molecular weight. The solution viscosity
exhibited a slope discontinuity from 1.8 to 3.7, indicating a transition from dilute
to semidilute unentangled behavior, which is characteristic of high molecular
