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DNA–polycation complexation and polyplex stability in the presence of competing polyanions
Author(s) -
Danielsen Signe,
Maurstad Gjertrud,
Stokke Bjørn T.
Publication year - 2004
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.20170
Subject(s) - chemistry , polyelectrolyte , ethidium bromide , chitosan , dna , static electricity , polymer , biophysics , lysine , ionic strength , polylysine , cationic polymerization , electrostatics , polymer chemistry , biochemistry , organic chemistry , amino acid , aqueous solution , electrical engineering , biology , engineering
Polyelectrolyte complex (polyplex) formation was studied by employing tapping mode atomic force microscopy (AFM) and an ethidium bromide fluorescence assay. The polycations chitosan and poly‐ L ‐lysine were used to compact DNA and the stability of the polyplexes was evaluated upon exposure to competing polyanions (alginate and xanthan). Furthermore, the relative preference of these polycations for DNA and the competing polyanion was investigated. The results showed that neither poly‐ L ‐lysine nor chitosan displayed any selectivity in binding to DNA relative to the competing polyanions, demonstrating the importance of electrostatics in the binding of a polycation to a polyanion. However, the ability of the polyanions to destabilize the DNA–polycation complexes depended on both the polyanion and the polycation employed, indicating that polymer‐specific properties are also important for the complexation behavior and polyplex stability. Destabilization experiments further showed that annealing yielded complexes that were less prone to disruption upon subsequent exposure to alginate. Annealing experiments of plasmid DNA–chitosan complexes showed an increased fraction of rods following temperature treatment, indicating that the rods most likely are the more stable morphology for this system. © 2004 Wiley Periodicals, Inc. Biopolymers, 2005