title: Association of star-shaped poly(D,L-lactide)s containing nucleobase multiple hydrogen bonding.
abstract: A new family of associating polymers based on four-arm, star-shaped poly(D,L-lactide) (PDLLA) containing peripheral complementary hydrogen-bonding sites is described. Hydroxy-terminated, four-arm, star-shaped PDLLAs of controlled molar mass were functionalized with complementary DNA base pairs, adenine (A) and thymine (T), to obtain PDLLA-A and PDLLA-T, respectively. 1H NMR spectroscopy confirmed quantitative functionalization and the subsequent formation of PDLLA-A and PDLLA-T hydrogen-bonded complexes. Job's analysis revealed a 1:1 optimal stoichiometry for the hydrogen-bonded complexes, and the association constant (Ka) that was determined using the 1H NMR-based Benesi-Hildebrand treatment was 84 M(-1) for the low molar mass complementary polymers. Furthermore, the PDLLA-based hydrogen-bonded complexes exhibited higher solution viscosities compared to the corresponding non-hydrogen-bonded precursors, which further confirmed strong complementary multiple-hydrogen-bonding associations between the star-shaped polymers with terminal adenine and thymine groups. Moreover, variable-temperature 1H NMR studies demonstrated the thermoreversibility of the hydrogen-bonded PDLLA-based complexes in solution.
authors.affiliation: Department of Chemistry, Macromolecules and Interfaces Institute, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
authors.forename: Afia S
authors.initials: AS
authors.lastname: Karikari
authors.forename: Brian D
authors.initials: BD
authors.lastname: Mather
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Long
mesh_terms: D001665:Binding Sites; D001671:Biochemistry / Q000379:methods; D004305:Dose-Response Relationship, Drug; D006860:Hydrogen Bonding; D007700:Kinetics; D019344:Lactic Acid / Q000737:chemistry*; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008970:Molecular Weight; D009696:Nucleic Acids / Q000737:chemistry*; D009711:Nucleotides / Q000737:chemistry*; D011091:Polyesters; D011108:Polymers / Q000737:chemistry*; D011312:Pressure; D013941:Thymine / Q000737:chemistry
chemical_list: D046911:Macromolecular Substances; D009696:Nucleic Acids; D009711:Nucleotides; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D013941:Thymine