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The complexation of linear double stranded DNA and poly(styrenesulfonate) (PSS) with cationic poly(dimethylamino ethyl methacrylate)-block-poly(n-butyl methacrylate) micelles was compared in aqueous solutions at various pH values and ionic strengths. The complexation process was monitored by turbidimetric titration, as a function of the ratio (N/P) of amine groups in the micelle corona to the number of phosphates (or sulfonates) in the polyanion. The size, structure and stability of the resulting micelleplexes were studied by dynamic light scattering (DLS) and cryogenic transmission electron microscopy (cryo-TEM). In the short chain regime, where the contour lengths of the polyanions are shorter than or comparable to the micelle corona thickness, micelleplexes with DNA oligomers show very similar behavior to complexes with short PSS chains, in terms of titration curves and structural evolution of the complexes as a function of charge ratio. However, in the long chain regime, where the contour length of the polyanion far exceeds the micelle radius, micelleplexes of linear DNA show titration curves shifted toward lower N/P ratios, reduced stability at N/P < 1, and a higher percentage of small complexes at N/P > 1 compared to complexes with long chain PSS. Furthermore, at 1 M ionic strength, the cationic micelles could still complex with long chain PSS, but not with DNA of the same total charge. These differences are attributed to the flexibility difference between the polyanion chains, and possible mechanisms are proposed. This work highlights the importance of chain flexibility in complexation of dissimilar polyelectrolyte pairs, a factor that could therefore help guide the future design of micelleplexes for various applications.
Bibliographical noteFunding Information:
This work was supported primarily by the National Science Foundation through the University of Minnesota MRSEC under Award Number DMR-1420013. Part of this work was carried out in the College of Science and Engineering Characterization Facility, University of Minnesota, which has received capital equipment funding from NSF through the UMN MRSEC program under Award Number DMR-1420013. J.E.L. was supported in part by the L'Oréal for Women in Science postdoctoral fellowship program, and Y. J. received a Louise T. Dosdall Fellowship.
© 2017 American Chemical Society.
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PubMed: MeSH publication types
- Journal Article
- Research Support, Non-U.S. Gov't
- Research Support, U.S. Gov't, Non-P.H.S.
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