Water-soluble polyion complex associates of DNA and poly(ethylene glycol)-poly(L-lysine) block copolymer.
Complex formation of poly(ethylene glycol)-poly(L-lysine) (PEG-PLL) AB type block copolymer with salmon testes DNA or Col E1 plasmid DNA in aqueous milieu was studied. The PLL segment of PEG-PLL interacts with nucleic acid through an electrostatic force to form a water-soluble complex associate with a diameter of ca. 50 nm. PEG segments surrounding the core of the polyion complex prevented the complex from precipitation even under stoichiometric conditions, at which the unit ratio of L-lysine in PEG-PLL and phosphate in the DNA is equal. The profile of the thermal melting curve revealed a higher stabilization of DNA structure in PEG-PLL/DNA complexes compared to that in the complex made from DNA and PLL homopolymer with the same molecular weight as the PLL segment in PEG-PLL. This stabilizing effect on the DNA structure may be due to the compartmentalization of DNA into the microenvironment of PEG with low permittivity. The reversible nature of the PEG-PLL/DNA complex was further verified through the addition of polyanion [poly-(L-aspartic acid)]: Poly(L-aspartic acid) replaced DNA in the complex with PEG-PLL, resulting in the release of free DNA in the medium. Furthermore, the PEG-PLL/DNA complex showed high resistance against DNase I attack, suggesting DNA protection through the segregation into the core of the associate having PEG palisade.
Katayose
S
S
Department of Materials Science and Technology, Science University of Tokyo, Chiba, Japan.
Kataoka
K
K
D000818:Animals; D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004247:DNA / Q000737:chemistry*; D004269:DNA, Bacterial / Q000737:chemistry; D003851:Deoxyribonucleases / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D008027:Light; D008297:Male; D008970:Molecular Weight; D011092:Polyethylene Glycols / Q000737:chemistry*; D011107:Polylysine / Q000737:chemistry*; D012474:Salmon; D012542:Scattering, Radiation; D012995:Solubility; D013737:Testis / Q000737:chemistry
C099578:(O-methylpoly(ethylene glycol)-O'-succinyl)-N-epsilon-poly(L-lysine); D004269:DNA, Bacterial; D011107:Polylysine; D011092:Polyethylene Glycols; D004247:DNA; D003851:Deoxyribonucleases