Structure-Property Relationships of Oligonucleotide Polyelectrolyte Complex Micelles

Michael Lueckheide, Jeffrey R. Vieregg, Alex J. Bologna, Lorraine Leon, Matthew V. Tirrell

Research output: Contribution to journalArticlepeer-review

68 Scopus citations


Polyelectrolyte complex micelles (PCMs), nanoparticles formed by electrostatic self-assembly of charged polymers with charged-neutral hydrophilic block copolymers, offer a potential solution to the challenging problem of delivering therapeutic nucleic acids into cells and organisms. Promising results have been reported in vitro and in animal models but basic structure-property relationships are largely lacking, and some reports have suggested that double-stranded nucleic acids cannot form PCMs due to their high bending rigidity. This letter reports a study of PCMs formed by DNA oligonucleotides of varied length and hybridization state and poly(l)lysine-poly(ethylene glycol) block copolymers with varying block lengths. We employ a multimodal characterization strategy combining small-angle X-ray scattering (SAXS), multiangle light scattering (MALS), and cryo-electron microscopy (cryo-TEM) to simultaneously probe the morphology and internal structure of the micelles. Over a wide range of parameters, we find that nanoparticle shape is controlled primarily by the hybridization state of the oligonucleotides with single-stranded oligonucleotides forming spheroidal micelles and double-stranded oligonucleotides forming wormlike micelles. The length of the charged block controls the radius of the nanoparticle, while oligonucleotide length appears to have little impact on either size or shape. At smaller length scales, we observe parallel packing of DNA helices inside the double-stranded nanoparticles, consistent with results from condensed genomic DNA. We also describe salt- and thermal-annealing protocols for preparing PCMs with high repeatability and low polydispersity. Together, these results provide a capability to rationally design PCMs with desired sizes and shapes that should greatly assist development of this promising delivery technology.

Original languageEnglish (US)
Pages (from-to)7111-7117
Number of pages7
JournalNano letters
Issue number11
StatePublished - Nov 14 2018
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2018 American Chemical Society.


  • coacervation
  • complexation
  • nanoparticles
  • Oligonucleotides
  • phase separation
  • polyelectrolytes


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