title: Hydrogen bonding versus ion pairing in polyelectrolyte multilayers with homopolynucleotides.
abstract: Homopolynucleotides--poly(adenylic acid), poly(A), and poly(uridylic acid), poly(U)--were assembled, layer-by-layer, into thin films with poly(ethylenimine), PEI. Various combinations and sequences of polynucleotide and PEI were used to highlight contributions of electrostatic versus hydrogen bonding as driving forces for multilayer build-up. Assembly of alternating poly(A) and poly(U) failed to yield growing films, due to excessively strong interactions between these complimentary strands. The surface morphology of multilayers depended on the deposition order and whether films had been annealed by salt. Films assembled from preformed A/U duplexes (having high persistence lengths) were very smooth. Individual adsorption steps, followed by optical waveguide light-mode spectroscopy, showed that only complementary polynucleotides adsorb by H-bonding to the surface of a growing multilayer. In contrast to behavior usually observed for polyelectrolyte multilayer build-up, the films decreased in thickness with increasing salt concentration.
authors.affiliation: Department of Chemistry and Biochemistry, Center for Materials Research and Technology, The Florida State University, Tallahassee, Florida 32306, USA.
authors.forename: Marie Z
authors.initials: MZ
authors.lastname: Markarian
authors.forename: Maroun D
authors.initials: MD
authors.lastname: Moussallem
authors.forename: Houssam W
authors.initials: HW
authors.lastname: Jomaa
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Schlenoff
mesh_terms: D000327:Adsorption; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002942:Circular Dichroism; D004305:Dose-Response Relationship, Drug; D004573:Electrolytes; D006860:Hydrogen Bonding; D007477:Ions; D018625:Microscopy, Atomic Force; D008968:Molecular Conformation; D009711:Nucleotides / Q000737:chemistry; D011094:Polyethyleneimine / Q000737:chemistry; D011119:Polynucleotides / Q000737:chemistry*; D012492:Salts / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors
chemical_list: D004573:Electrolytes; D007477:Ions; D009711:Nucleotides; D011119:Polynucleotides; D012492:Salts; D011094:Polyethyleneimine