title: Thermoresponsive micellization and micellar stability of poly(N-isopropylacrylamide)-b-DNA diblock and miktoarm star polymers.
abstract: Linear and miktoarm star-shaped diblock copolymers consisting of single-stranded DNA and poly(N-isopropylacrylamide) (PNIPAAm) with various compositions were synthesized via atom transfer radical polymerization and click chemistry. The temperature-responsive phase transition behavior, micellization, was systematically examined using UV-vis spectrometry, high-sensitivity differential scanning calorimetry, dynamic light scattering, and small-angle X-ray scattering. The lower critical solution temperature (LCST) increased, and its enthalpy decreased with decreasing PNIPAAm content. 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. On the other hand, regardless of their factors, the surface area occupied by one DNA strand was found to be almost unchanged. The hybridization of DNA on the nanoparticles with fully complementary one induced the aggregation of the particles in a non-cross-linking configuration. The nanoparticle composed of miktoarm star copolymer showed a quicker DNA-hybridization response in this non-cross-linking aggregation compared with the case of a linear analogue.
authors.affiliation: Bioengineering Laboratory, RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198, Japan.
authors.forename: Pengju
authors.initials: P
authors.lastname: Pan
authors.forename: Masahiro
authors.initials: M
authors.lastname: Fujita
authors.forename: Wei-Yang
authors.initials: WY
authors.lastname: Ooi
authors.forename: Kumar
authors.initials: K
authors.lastname: Sudesh
authors.forename: Tohru
authors.initials: T
authors.lastname: Takarada
authors.forename: Atsushi
authors.initials: A
authors.lastname: Goto
authors.forename: Mizuo
authors.initials: M
authors.lastname: Maeda
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D001483:Base Sequence; D003102:Colloids; D004277:DNA, Single-Stranded / Q000737:chemistry* / Q000235:genetics; D008823:Micelles; D053758:Nanoparticles / Q000737:chemistry; D009693:Nucleic Acid Hybridization; D044367:Phase Transition; D013696:Temperature
chemical_list: D000180:Acrylic Resins; D003102:Colloids; D004277:DNA, Single-Stranded; D008823:Micelles; C052970:poly-N-isopropylacrylamide