Structure/function relationships of polyamidoamine/DNA dendrimers as gene delivery vehicles

Chad S. Braun, Joseph A. Vetro, Donald A. Tomalia, Gary S. Koe, Janet G. Koe, C. Russell Middaugh

Research output: Contribution to journalArticlepeer-review

221 Scopus citations


PAMAM dendrimers are members of a class of polyamine polymers that demonstrate significant gene delivery ability. In this study, a selection of PAMAM dendrimers, spanning a range of sizes (generations 2, 4, 7, and 9) and transfection efficiencies, are characterized by various biophysical methods to search for structural properties that correlate with transfection. Measurements of colloidal properties (size and zeta potential) as a function of charge ratio reveal that highly transfecting dendrimer/DNA complexes have size/zeta potential values between 4 and 8. Circular dichroism (CD) and FTIR spectroscopy of complexes confirm the DNA component remains in B form when associated with all dendrimer generations up to a 5:1 charge ratio (±). Isothermal titration calorimetry and differential scanning calorimetry detect changes that are related to polymer structure and charge ratio but do not directly correlate with transfection efficiency. Despite DNA structural and stability changes detected by CD, FTIR, DSC, and ITC that are similar to those seen with other cationic delivery vehicles [e.g., cationic lipids, peptoids/lipitoids, peptides, polyethyleneimines (PEIs), etc.], clear correlations with transfection activity are not readily apparent. This may be due, at least in part, to the heterogeneity of the complexes.

Original languageEnglish (US)
Pages (from-to)423-436
Number of pages14
JournalJournal of Pharmaceutical Sciences
Issue number2
StatePublished - Feb 2005
Externally publishedYes


  • DNA
  • Dendrimers
  • Gene delivery
  • Structure/function analysis

ASJC Scopus subject areas

  • Pharmaceutical Science


Dive into the research topics of 'Structure/function relationships of polyamidoamine/DNA dendrimers as gene delivery vehicles'. Together they form a unique fingerprint.

Cite this