Presentation day

Wednesday  4:20 PM

 

TITLE

Structural Characteristics of DNA-Poly(N-isopropylacrylamide) Bioconjugate

 

Abstract

Single-stranded (ss) DNA-poly(N-isopropylacrylamide) (PNIPAAm) bioconjugate selfassembles
to form colloidal nanoparticles above its lower critical solution temperature (LCST). When the
ssDNA on the particle surface hybridizes with its fully complementary DNA, the particles aggregate with
drastically increased turbidity in solution. If double-stranded (ds) DNA contains a single-base mismatch at
the free terminus, the particles remain dispersed stably. The DNA-PNIPAAm bioconjugate is thus expected
as a functional material for turbidimetric detection of single nucleotide polymorphism. Recently, we have
succeeded in the synthesis of well-defined PNIPAAm-b-ssDNA conjugates with respect to molecular
weight, composition, and architecture, which are the crucial factors in self-assembly, are essential for the
fabrication of DNA-encoded micelles with controllable morphology and for the optimization of the functions.
The temperature-responsive phase transition behavior was systematically examined using UV-Vis
spectrometry, high-sensitivity differential scanning calorimetry, dynamic light scattering, and small-angle Xray
scattering. The copolymers self-assembled into well-defined nanoparticles having a core composed of
PNIPAAm and a coronal layer of DNA above LCST. The particle size and micellar aggregation number of
copolymer chains depended on the macromolecular composition and chain architecture. The hybridization
of DNA on the nanoparticles with fully complementary one induced the aggregation of the particles in a non
-crosslinking configuration. The nanoparticle composed of miktoarm star copolymer showed a quicker DNA
-hybridization response in this non-crosslinking aggregation, compared with the case of linear analogue.