Ionic, structural, and temperature effects on DNA nanoparticles formed by natural and synthetic polyamines

Veena Vijayanathan, Jasleen Lyall, Thresia Thomas, Akira Shirahata, T. J. Thomas

Research output: Contribution to journalArticle

35 Scopus citations


We synthesized analogues of spermine and studied the effects of chemical structure, ionic strength, and temperature on λ-DNA nanoparticle formation. Effective concentration of polyamines for DNA condensation (EC50) was lowest for hexamines (0.2 μM) and highest for spermine (tetramine, 4.2 μM). The EC50 value increased with [Na+]. Dynamic light scattering showed nanoparticles with hydrodynamic radii (Rh) of 40-50 nm. Effect of temperature on Rh was measured between 20 and 70 °C. For spermine, Rh remained relatively stable until 50 °C and increased significantly at >60 °C. In contrast, the hexa- and penta-valent analogues exhibited a gradual increase in Rh between 20 and 70 °C. The nanoparticles were mainly toroidal, as revealed by electron microscopy (EM). EM studies showed changes in morphology and size of condensed structures with an increase in temperature. A possible mechanism for the differential effects of temperature on DNA nanoparticles might involve different modes of DNA-polyamine interactions.

Original languageEnglish (US)
Pages (from-to)1097-1103
Number of pages7
Issue number2
StatePublished - Mar 1 2005


ASJC Scopus subject areas

  • Bioengineering
  • Biomaterials
  • Polymers and Plastics
  • Materials Chemistry

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